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The immunopathogenesis of sepsis
Abstract
Sepsis is a condition that results from a harmful or damaging host response to infection. Many of the components of the innate immune response that are normally concerned with host defences against infection can, under some circumstances, cause cell and tissue damage and hence multiple organ failure, the clinical hallmark of sepsis. Because of the high mortality of sepsis in the face of standard treatment, many efforts have been made to improve understanding of the dysregulation of the host response in sepsis. As a result, much has been learnt of the basic principles governing bacterial-host interactions, and new opportunities for therapeutic intervention have been revealed.
... Los mecanismos reguladores de la coagulación de la sangre se alteran gravemente durante la sepsis, lo que da como resultado el depósito de fibrina en la microcirculación, que se cree que es la principal causa de insuficiencia orgánica. 7 Cuando la fibrina se descompone se crea una molécula llamada dímero D y la concentración de esta molécula aumenta en la sepsis como resultado de la fibrinolisis. El dímero D también está elevado en coagulación intravascular diseminada, lo que indica que el mecanismo de coagulación se ha activado. ...
... 9 Existen receptores que serán capaces de dar inicio a la respuesta inmune celular, éstos son los receptores de reconocimiento de patrones (PRR), algunos ejemplos son los recetores tipo Toll, recetores de lectina tipo C, receptor depurador de macrófagos (MSR), dominio de oligomerización por unión de nucleótidos que contiene la proteína 1-2 (NOD-1, NOD-2). 7 Existen diversos recetores tipo Toll y cada uno de éstos es específico para un ligando y, por ende, a uno o varios agentes patógenos. El recetor TLR-4 tiene su ligando en los lipopolisacáridos, con su agente patógeno en bacterias Gram negativas. ...
... In the study, 24 Sprague-Dawley-Albino male rats (16)(17)(18)(19)(20) weeks old) with an average weight of 297 ± 20 g were used. The rats were kept in a 12-hour light-dark cycle, with the moisture of approximately 55%-60%, and ventilated room with a temperature of 20-22°C where the floors of special cages were cleaned daily. ...
... In addition to these, IL-1β is also involved in several critical cellular activities such as proliferation, activation, and differentiation, as well as induces leukocyte phagocytosis and chemotaxis. [18][19][20] In this current study, we expected a significant decrease in TNF-α levels, a proinflammatory cytokine such as IL-1β, in treatment groups. However, the absence of a decrease was probably attributed to the fact that TNF is a locally released cytokine, and therefore, the increase and decrease in tissues cannot be adequately reflected in the systemic circulation. ...
Resveratrol has histone 4 and beta-defensin 1-mediated favorable biotherapeutic effects on liver and other target organs in diabetic rats. Turk J Gastroenterol. 2024;35(3):223-231. ABSTRACT Background/Aims: It was aimed to investigate the biochemical and histopathological effects of resveratrol and melatonin, via histone H4 and β-defensin 1, in diabetic rats. Materials and Methods: Twenty-four Sprague-Dawley male rats were categorized into 4 groups, with 6 rats in each group (control, diabetes mellitus, melatonin-diabetes mellitus, and resveratrol + diabetes mellitus). Diabetes was formed by giving streptozotocin to all groups except the control group. Melatonin, 5 mg/kg/day, was given to the melatonin-diabetes mellitus group, and resveratrol, 5 mg/kg/day, was given to the resveratrol + diabetes mellitus group via intraperitoneally for 3 weeks. Interleukin-1 beta, tumor necrosis factor alpha, histone H4, and β-defensin 1 levels were measured in the blood of all rats. The lung, liver, and kidney tissue of all rats were performed as histopathological examinations. Results: Whereas there was no difference between the other groups (P > .05), interleukin-1 beta levels of the diabetes mellitus group were found to be significantly higher compared with the control group (5.02 ± 2.15 vs. 2.38 ± 0.72 ng/mL; P < .05). Whereas histone H4 levels of the diabetes mellitus group were higher compared with the control and resveratrol + diabetes mellitus groups (7.53 ± 3.30 vs. 2.97 ± 1.57 and 3.06 ± 1.57 ng/mL; P < .05), the β-defensin 1 levels of the diabetes mellitus group were lower compared with control and resveratrol + diabetes mellitus groups (7.6 ± 2.8 vs. 21.6 ± 5.5 and 18.8 ± 7.4 ng/mL; P < .05). β-Defensin 1 levels were moderately inversely correlated with interleukin-1 beta and histone H4 levels (rs > −0.50, P < .01). Histopathological changes found in favor of target cell damage in the diabetes mellitus group were not observed in resveratrol + diabetes mellitus group. Conclusion: Resveratrol may be used as a biotherapeutic agent, which significantly reduces diabetes-induced histone H4 and interleu-kin-1 beta-mediated liver and other target organ damage.
... In light of these mechanisms, we can consider that the increase in neutrophil infiltration/aggregation seen in the CLP may result from a high neutrophil half-life and leukocytosis [20][21][22][23][24]. Makled et al. showed that pomegranate extract attenuated inflammatory cell infiltration and TLR4 expression in CLP liver injury [25]. Biddle et al. reported that proinflammatory cytokines were decreased with PSO in necrotizing enterocolitis [26]. We demonstrate that a high dose of PSO (0.64 mg/kg) reduced neutrophil infiltration/aggregation. ...
... Thus, we reported that PSO has scavenging activity. Pomegranates do have not only scavenger activity but also metal chelates [26]. Studies about the chelate binding feature of PSO are absent from the literature. ...
Objectives: Sepsis is a common disease with a high mortality. Decreasing the speed is possible with early and intensive therapy. However, most medicines have been tested, but none has proven effective. Therefore, the study aimed to discover the protective and therapeutic effects of pomegranate seed oil (PSO). Methods: The cecal ligation puncture (CLP) method was used to induce sepsis. The experimental procedure was started with the animals divided haphazardly into four groups: control (C), sepsis (CLP), CLP + low dose PSO (CLP + LD), and CLP + high dose PSO (CLP + HD). First, the cecum was filled with feces. The full cecum was tied under the ileocecal valve for ligation and punctured. At 1 hour after CLP, 0.32 mg/kg and 0.64 mg/kg of PSO were administered. 24 hours after, lung and kidney specimens were collected. Results: Neutrophil infiltration/aggregation and alveolar wall thickness decreased in lung with PSO groups compared with the CLP. The findings for overall lung injury were similar. In renal, all parameters were increased in the CLP compared with C, except for vascular vacuolization and hypertrophy. According to the CLP, all parameters were significantly lower in CLP + HD. Furthermore, glomerular vacuolization, degeneration, and necrosis of tubular cell, dilatation of bowman space, and tubular hyaline cylinders reduced CLP + LD versus CLP. Thiobarbituric acid-reactive substances decreased in lung, with the PSO groups. In addition, superoxide dismutase increased in PSO groups versus CLP. Conclusions: We conclude that the high-dose PSO is especially effective in treating sepsis.
... Recent studies also point to a key role for proinfl ammatory cytokines in the non-osmotic release of ADH by the hypothalamic-pituitary axis [12][13][14] commonly known as the syndrome of inappropriate ADH (SIADH). Although an anti-infl ammatory effect of ADH on induced generalized infl ammation as in sepsis condition has been suggested [15], the opposite was also noted that pro-infl ammatory cytokines such as TNF, released from infl ammatory stress condition can activate the hypothalamus to produce ADH [14,15]. ...
Hyponatremia is a life-threatening situation in severe inflammatory disorders. Managing this disorder is seriously hampered because its underlying pathophysiology has remained elusive. An increase in tumor necrosis factor-alpha (TNFα) during systemic inflammation may be involved in this hyponatremic mechanism as it is known that circulating TNFα exerts potent natriuresis via its action on receptor type 1 (TNFR1). Systemic inflammation also induces non-osmotic release of Antidiuretic Hormone (ADH), commonly known as ‘Syndrome of Inappropriate ADH’ (SIADH), that would cause water retention to increase in Extracellular Fluid Volume (ECV). Thus, the inflammation-induced TNFR1 activation and sodium loss coupled with SIADH-induced increases in ECV, would lead to the serious condition of hypervolemic hyponatremia. In this brief review, some experimental evidence will be provided that indicates TNFR1 activation during the inflammatory process can be targeted therapeutically to prevent such critical conditions of hypervolemic hyponatremia. The importance of these co-morbidities also extends to several other clinical scenarios of hyponatremia observed in patients with heart failure, liver disease, and renal disease. Besides the pathophysiological insights, the recognition of the propensity for both antidiuresis and natriuresis during inflammation is critically important in selecting the appropriate intravenous fluid regimens in patients with this disorder such as in the coronavirus disease of 2019 (COVID-19).
... In sepsis, the anti-inflammatory response mediated by molecules, such as IL-10, IL-4 and TGF-β, is finalised to preserve tissues and mitigate organ damage caused by the initial pro-inflammatory response. However, dysregulated and/or persistent activation of antiinflammatory mediators/pathways may cause severe failure of the immune system, defined as immune paralysis, characterised by impaired phagocytosis, alteration of cytokine profile, inadequacy of antigenpresenting mechanisms and dysfunction and apoptosis of B and T lymphocytes [13,14]. Patients with immune paralysis are unable to mount an appropriate inflammatory response and are prone to viral reactivation and secondary or breakthrough infections, mostly caused by opportunistic agents with limited treatment resources, such as Acinetobacter spp. ...
Background
In the last decades, several adjunctive treatments have been proposed to reduce mortality in septic shock patients. Unfortunately, mortality due to sepsis and septic shock remains elevated and NO trials evaluating adjunctive therapies were able to demonstrate any clear benefit. In light of the lack of evidence and conflicting results from previous studies, in this multidisciplinary consensus, the authors considered the rational, recent investigations and potential clinical benefits of targeted adjunctive therapies.
Methods
A panel of multidisciplinary experts defined clinical phenotypes, treatments and outcomes of greater interest in the field of adjunctive therapies for sepsis and septic shock. After an extensive systematic literature review, the appropriateness of each treatment for each clinical phenotype was determined using the modified RAND/UCLA appropriateness method.
Results
The consensus identified two distinct clinical phenotypes: patients with overwhelming shock and patients with immune paralysis. Six different adjunctive treatments were considered the most frequently used and promising: (i) corticosteroids, (ii) blood purification, (iii) immunoglobulins, (iv) granulocyte/monocyte colony-stimulating factor and (v) specific immune therapy (i.e. interferon-gamma, IL7 and AntiPD1). Agreement was achieved in 70% of the 25 clinical questions.
Conclusions
Although clinical evidence is lacking, adjunctive therapies are often employed in the treatment of sepsis. To address this gap in knowledge, a panel of national experts has provided a structured consensus on the appropriate use of these treatments in clinical practice.
... Although the exact pathogenesis of sepsis is not yet understood, growing research holds that immunosuppression is the central link in the pathogenesis of sepsis [4]. It was once believed that early sepsis-AGING induced death was a multi-organ failure caused by immune damage due to excessive inflammatory response, and early death can occur within a few hours to a few days, or even shorter time [5]. Later death of sepsis is caused by organ failure due to compensatory anti-inflammatory response-mediated immune damage, or by secondary severe infection due to severe immunosuppression, which both can occur days to weeks later [6]. ...
This study is aimed to explore the value of lymphocyte subsets in evaluating the severity and prognosis of sepsis. The counts of lymphocytes, CD3+ T cells, CD4+ T cells, CD8+ T cells, CD19+ B cells, and NK cells significantly decreased between day 1 and day 3 in both the survivor and the non-survivor groups. The peripheral lymphocyte subsets (PLS) at day 1 were not significantly different between the survivor and the non-survivor groups. However, at day 3, the counts of lymphocytes, CD3+ T cells, CD4+ T cells, and NK cells were remarkably lower in the non-survivor group. No significant differences in CD8+ T cells, or CD19+ B cells were observed. The PLS index was independently and significantly associated with the 28-day mortality risk in septic patients (OR: 3.08, 95% CI: 1.18-9.67). Based on these clinical parameters and the PLS index, we developed a nomograph for evaluating the individual mortality risk in sepsis. The area under the curve of prediction with the PLS index was significantly higher than that from the model with only clinical parameters (0.912 vs. 0.817). Our study suggests that the decline of PLS occurred in the early stage of sepsis. The new novel PLS index can be an independent predictor of 28-day mortality in septic patients. The prediction model based on clinical parameters and the PLS index has relatively high predicting ability.
... Sepsis is a life-threatening systemic inflammatory response (SIRS) to infection, leading to possible organ failure and death (1). Sepsis is the primary cause of death in most intensive care units (ICUS), warranting early detection and appropriate treatment. ...
Sepsis is a systemic inflammatory response to a severe, life-threatening infection with organ dysfunction. Although there is no effective treatment for this fatal illness, a deeper understanding of the pathophysiological basis of sepsis and its underlying mechanisms could lead to the development of new treatment approaches. Here, we demonstrate that the selective Bruton’s tyrosine kinase (Btk) inhibitor acalabrutinib augments survival rates in a lipopolysaccharide (LPS)-induced septic model. Our in vitro and in vivo findings both indicate that acalabrutinib reduces IL-6 production specifically in marginal zone B (MZ B) cells rather than in macrophages. Furthermore, Btk-deficient MZ B cells exhibited suppressed LPS-induced IL-6 production in vitro. Nuclear factor-kappa B (NF-κB) signaling, which is the downstream signaling cascade of Toll-like receptor 4 (TLR4), was also severely attenuated in Btk-deficient MZ B cells. These findings suggest that Btk blockade may prevent sepsis by inhibiting IL-6 production in MZ B cells. In addition, although Btk inhibition may adversely affect B cell maturation and humoral immunity, antibody responses were not impaired when acalabrutinib was administered for a short period after immunization with T-cell-independent (TI) and T-cell-dependent (TD) antigens. In contrast, long-term administration of acalabrutinib slightly impaired humoral immunity. Therefore, these findings suggest that Btk inhibitors may be a potential option for alleviating endotoxic shock without compromising humoral immunity and emphasize the importance of maintaining a delicate balance between immunomodulation and inflammation suppression.
... Sepsis is widely recognized as a clinical syndrome, resulting from an overwhelming systemic host response to infection [1]. The key clinical manifestations of sepsis are not caused directly by the invading pathogens; rather, the hypotension, coagulopathy, and multisystem organ dysfunction that characterize severe sepsis are predominantly a result of dysregulation of host-derived mediators of inflammation [2]. ...
Background and objectives. Sepsis is a critical clinical syndrome characterized by a systemic host response to infection, often leading to organ dysfunction and mortality. The association between early onset coagulopathy and mortality risk in septicemic patients remains an area of active investigation. This study aims to assess the association between early onset coagulopathy and increased mortality risk in septicemic patients. It also seeks to explore the role of procalcitonin (PCT) levels and demographic factors in the prognosis of septicemia. Material and methods. A cross-sectional study was conducted at Saveetha Medical College and Hospital, including 240 subjects who met the inclusion criteria. Patients were evaluated for the presence of coagulopathy (assessed by platelet count, INR, and aPTT values) and their PCT levels within 48 hours of admission. Data on demographic characteristics, underlying illnesses, and 28-day mortality were collected and analyzed. Results. The study population had a male preponderance (53.3%) with a mean age of 56.27 years. Diabetes mellitus was the most common underlying illness (32.5%). Coagulopathy was observed in 52.5% of patients, with thrombocytopenia and deranged INR and aPTT being significant indicators. Patients with life-threatening thrombocytopenia, severe PT-INR, and aPTT derangements showed high mortality rates (100%, 92.4%, and 90%-95.6% respectively). Mortality was significantly associated with coagulopathy and elevated PCT levels (>10.0 ng/ml), with 41.7% of subjects dying within 28 days of admission. Conclusions. Early onset coagulopathy is significantly associated with increased mortality in septicemic patients, highlighting the importance of coagulation parameters and PCT levels in predicting outcomes indicating prompt recognition and management of coagulopathy in septicemia, especially in younger patients and those with elevated PCT levels.
... In general, early proinflammatory activation in response to invading pathogens or danger signals is associated with the onset of multiorgan failure and early death, whereas immunosuppression is associated with the reactivation of latent infection and delayed death. The degree of immune activation and immunosuppression, along with their impact on the immune response associated with sepsis, varies among individual patients [25,26,28]. ...
... Additionally, it was also observed that lipopolysaccharide biosynthesis proteins and lipopolysaccharide biosynthesis exhibited larger absolute value in the SP group. Intestinal injury can lead to an elevation in intestinal mucosal permeability, particularly allowing lipopolysaccharide (LPS) from the outer membrane of Gram-negative bacteria to enter the bloodstream and trigger chronic inflammation [46]. Our study revealed that consumption of a SP diet alone is not conducive to intestinal health and may cause minor intestinal damage, as evidenced by significant villi breakage and insufficient fullness observed in the SP group's intestinal morphology. ...
Purpose
The impact of dietary nutrients on body growth performance and the composition of gut microbes and metabolites is well-established. In this study, we aimed to determine whether dietary protein can regulate the physiological indexes and changes the intestinal tissue morphology in rats, and if dietary protein was a crucial regulatory factor for the composition, function, and metabolic pathways of the gut microbiota.
Method
A total of thirty male Sprague Dawley (SD) rats (inbred strain, weighted 110 ± 10 g) were randomly assigned to receive diets containing animal-based protein (whey protein, WP), plant-based protein (soybean protein, SP), or a blended protein (soybean-whey proteins, S-WP) for a duration of 8 weeks. To investigate the effects of various protein supplement sources on gut microbiota and metabolites, we performed a high throughput 16S rDNA sequencing association study and fecal metabolomics profiling on the SD rats. Additionally, we performed analyses of growth indexes, serum biochemical indexes, and intestinal morphology.
Results
The rats in S-WP and WP group exhibited a significantly higher body weight and digestibility of dietary protein compared to the SP group (P < 0.05). The serum total protein content of rats in the WP and S-WP groups was significantly higher (P < 0.05) than that in SP group, and the SP group exhibited significantly lower (P < 0.05) serum blood glucose levels compared to the other two groups. The morphological data showed the rats in the S-WP group exhibited significantly longer villus height and shallower crypt depth (P < 0.05) than the SP group. The gut microbial diversity of the SP and S-WP groups exhibited a higher level than that of the WP group, and the microbiomes of the WP and S-WP groups are more similar compared to those of the SP group. The Arachidonic acid metabolism pathway is the most significant KEGG pathway when comparing the WP group and the SP group, as well as when comparing the SP group and the S-WP group.
Conclusion
The type of dietary proteins exerted a significant impact on the physiological indices of SD rats. Intake of S-WP diet can enhance energy provision, improve the body’s digestion and absorption of nutrients, as well as promote intestinal tissue morphology. In addition, dietary protein plays a crucial role in modulating fecal metabolites by regulating the composition of the gut microbiota. Metabolomics analysis revealed that the changes in the levels of arachidonic acid metabolites and secondary bile acid metabolite induced by Clostridium_sensu_stricto_1 and [Eubacterium]_coprostanoligenes_group maybe the primarily causes of intestinal morphological differences.
... This downstream signaling pathway leads to the activation and translocation of NF-κβ dimer to the nucleus where it induces the transcription of various target genes including those for production of inflammatory cytokines. 8 The excessive production of inflammatory cytokines during sepsis may worsen the outcome causing capillary leakage, tissue injury, and multiple organ failure. 2 Septic patients had higher levels of plasma tumor necrosis factor alpha (TNF-α) and interleukin (IL)-1β which correlated with the severity of illness. 9 Cytokines such as TNF-α and IL-1β peak within the first few hours of sepsis, thus providing a narrow therapeutic window. ...
Narciclasine is an alkaloid belonging to the Amaryllidaceae family which has been reported to have many beneficial properties. Especially its anticancer properties have been widely reported. Here, we have focused on its potential use in suppressing the inflammatory response in sepsis using in silico methods. Lipopolysaccharide (LPS) is an endotoxin which is present in the outer membrane of gram-negative bacteria and is a crucial player in the pathogenesis of gram-negative sepsis. Activation of toll-like receptor 4 (TLR4) signaling by LPS is an important event in the pathogenesis of gram-negative sepsis. This initiates a downstream signaling pathway comprising of several adaptor proteins such as toll/interleukin-1 receptor domain-containing adapter protein (TIRAP), myeloid differentiation primary response protein 88 (MyD88), interleukin-1 receptor–associated kinase (IRAK)-1, IRAK-4, interferon regulatory factor 3 (IRF-3), tumor necrosis factor receptor–associated factor 6 (TRAF-6) leading to nuclear factor kappa B (NF-κβ) activation resulting in elevated production of inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin (IL)-6. S100 calcium binding proteins A8/A9 (S100A8/A9) have been found to be an agonist of TLR4, and it amplifies the inflammatory response in sepsis. Molecular docking studies of narciclasine with target proteins associated with the LPS-TLR4 pathway showed that it has good binding affinity and stable interactions with the targets studied. Molecular dynamics (MD) simulation studies over 100 ns showed that most of the ligand-target complexes were stable. The structures of all the targets except TRAF-6 were retrieved from the Protein Data Bank (PDB) database. Homology modeling was done to predict the 3-dimensional structure of TRAF-6. MD simulation of narciclasine-TRAF-6 complex showed that the structure is stable. Metapocket was used for active site prediction in the target proteins. Toxicity analysis by admetSAR revealed that narciclasine was readily biodegradable and exhibited minimum toxicity. These results indicate that narciclasine has effective anti-inflammatory properties which could be useful in suppressing the inflammatory response in sepsis.
... Sepsis is a life-threatening condition that can lead to organ failure in association with high mortality and morbidity, particularly in intensive care units. Sepsis is characterised by excessive systemic inflammation that occurs through uncontrolled and abnormal innate immune responses during overwhelming microbial infections [1][2][3]. Toll-like receptors (TLRs) are pattern recognition receptors (PRRs) that respond to pathogen-associated molecular patterns (PAMPs), which are conserved components of microorganisms [4]. Among these, TLR4 is responsible for sensing lipopolysaccharide (LPS), a component of the outer membrane of Gram-negative bacteria and an important cause of sepsis. ...
Sepsis, a leading cause of death worldwide, is a harmful inflammatory condition that is primarily caused by an endotoxin released by Gram-negative bacteria. Effective targeted therapeutic strategies for sepsis are lacking. In this study, using an in vitro and in vivo mouse model, we demonstrated that CM1, a derivative of the natural polyphenol chrysin, exerts an anti-inflammatory effect by inducing the expression of the ubiquitin-editing protein TNFAIP3 and the NAD-dependent deacetylase sirtuin 1 (SIRT1). Interestingly, CM1 attenuated the Toll-like receptor 4 (TLR4)-induced production of inflammatory cytokines by inhibiting the extracellular-signal-regulated kinase (ERK)/MAPK and nuclear factor kappa B (NF-κB) signalling pathways. In addition, CM1 induced the expression of TNFAIP3 and SIRT1 on TLR4-stimulated primary macrophages; however, the anti-inflammatory effect of CM1 was abolished by the siRNA-mediated silencing of TNFAPI3 or by the genetic or pharmacologic inhibition of SIRT1. Importantly, intravenous administration of CM1 resulted in decreased susceptibility to endotoxin-induced sepsis, thereby attenuating the production of pro-inflammatory cytokines and neutrophil infiltration into the lung compared to control mice. Collectively, these findings demonstrate that CM1 has therapeutic potential for diverse inflammatory diseases, including sepsis.
... Moreover, macrophages and monocytes release IL-1β and soluble TNF-α, which in turn stimulates local production of other cytokines, including the neutrophil chemotactic factor IL-8 [6]. Furthermore, TNF-α and IL-1β play a major role in the activation of the inflammatory cascades that result in the initiation of inflammatory cell migration into tissue [32,33]. ...
... It is known that in response to infection, Toll-like receptors (TLR) bind to bacterial-derived lipopolysaccharide (LPS) and trigger an inflammatory response by activating the nuclear factor-kB (NF-kB) signaling pathway, which leads to the secretion of inflammatory cytokines, both pro-inflammatory and anti-inflammatory, further boosting hematopoiesis, phagocytosis, and leukocyte recruitment 24 . However, ALP can reduce the release of proinflammatory cytokines via the LPS-TLR4 pathway 25 . ...
The alkaline phosphatase-to-albumin ratio (APAR) is correlated to worse prognosis in coronary artery disease, cancer, and acute renal failure. However, the relationship between APAR and sepsis prognosis has received little research. The content of this research was to investigate the prognostic relationship between APAR and sepsis. And validate the stability of the correlation in 90-days and 1-year mortality. Retrospective cohort research was conducted basing MIMIC-IV database (version 2.0). The hazard ratio (HR) and 95% confidence interval (Cl) were computed using multivariate Cox regression analysis. In addition, plots of survival curves and subgroup analyzes were conducted. Receiver operating characteristic (ROC) curves were also used. 9741 participants were included in this investigation. The 90-days mortality was 32.8%, and the 1-year mortality was 42.0%. After controlling for confounders, the adjusted HRs (95% CI) for tertile 2 (2.2–3.8) and tertile 3 (> 3.8) were 1.37 (1.25–1.51) and 1.74 (1.58–1.91), respectively. The Kaplan–Meier curve analysis showed a higher probability of 90-days death in the higher APAR group. The area under the curve (AUC) of APAR was 0.674 and could reach 0.709 after combining the Oxford Acute Severity of Illness Score (OASIS). This study demonstrates that APAR is significantly related to bad clinical outcomes in sepsis.
... In response to systemic LPS, the organism releases pro-inflammatory substances, cytokines, into the circulatory system [2]. This condition is present in most cases of the equine acute abdomen as a consequence of the systemic inflammatory response syndrome, resulting in complications like jugular thrombophlebitis, laminitis, and adynamic ileum, among others, decreasing the short and long-term survival rates of horses with this disease [3][4][5]. ...
Simple Summary
Endotoxemia in horses is a serious condition caused by diseases that result in systemic inflammation, such as colic, pleuropneumonia, metritis, etc., and can lead to death. Finding a treatment or prevention for this condition is of great importance for the health of horses. The β-glucans present in yeast, especially Saccharomyces cerevisia, are supplemented with nutritional properties that induce the modulation of the immune system. This study aims to evaluate whether supplementing horses’ diets with β-glucans is capable of modulating horses’ immune response to the inflammatory stimulus caused by the intravenous injection of endotoxins (E. coli lipopolysaccharide; 0.1 µg/kg/body weight). It was found that there is a positive interference with this supplementation, with evidence of the modulation of the immune system, which encourages its use as a dietary supplement in order to assist the immune response of horses in cases of endotoxemia.
Abstract
β-glucan is part of the cell wall of fungi and yeasts and has been known for decades to have immunomodulating effects on boosting immunity against various infections as a pathogen-associated molecular pattern that is able to modify biological responses. β-glucan has been used in rat models and in vitro studies involving sepsis and SIRS with good results, but this supplement has not been evaluated in the treatment of endotoxemia in horses. This study aims to evaluate the effects of preventive supplementation with β-glucan in horses submitted to endotoxemia by means of inflammatory response modulation. Eight healthy horses, both male and female, aged 18 ± 3 months, weighing 300 ± 100 kg of mixed breed, were randomly assigned to two groups of four animals, both of which were subjected to the induction of endotoxemia via the intravenous administration of E. coli lipopolysaccharides (0.1 µg/kg). For 30 days before the induction of endotoxemia, horses in the β-glucan group (GB) received 10 mg/kg/day of β-glucan orally, and horses in the control group (GC) received 10 mg/kg/day of 0.9% sodium chloride orally. The horses were submitted to physical exams, including a hematological, serum biochemistry, and peritoneal fluid evaluation, and the serum quantification of cytokines TNF-α, IL-6, IL-8, and IL-10. For statistical analysis, the normality of residues and homogeneity of variances were verified; then, the variables were analyzed as repeated measures over time, checking the effect of treatment, time, and the interaction between time and treatment. Finally, the averages were compared using Tukey’s test at a significance level of 5%. Horses from both experimental groups presented clinical signs and hematological changes in endotoxemia, including an increase in heart rate and body temperature, neutrophilic leukopenia, an increase in serum bilirubin, glucose, lactate, and an increase in TNF-α, IL-6, and IL-10. Hepatic and renal function were not compromised by β-glucan supplementation. GB presented higher mean values of the serum total protein, globulins, and IL-8 compared to that observed in GC. In the peritoneal fluid, horses from GB presented a lower mean concentration of neutrophils and a higher mean concentration of macrophages compared to the GC. It was concluded that preventive supplementation of β-glucan for thirty days modulated the immune response, as evidenced by increasing serum total proteins, globulins, IL-8, and changes in the type of peritoneal inflammatory cells, without effectively attenuating clinical signs of endotoxemia in horses. Considering the safety of β-glucan in this study, the results suggest the potential clinical implication of β-glucan for prophylactic use in horse endotoxemia.
... Sepsis is a life-threatening medical emergency with organ dysfunction that can lead to high mortality and morbidity, especially in intensive care units worldwide, and is characterized by an excessive systemic inflammation that occurs through uncontrolled and abnormal innate immune Disclaimer/Publisher's Note: The statements, opinions, and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions, or products referred to in the content. 2 responses during overwhelming microbial infection [1,2]. Toll-like receptors (TLRs) are one of the best-characterized pattern recognition receptors (PRRs) and recognize pathogen-associated molecular patterns (PAMPs) that conserved structures of microbial species [3]. ...
Human sepsis is one of the leading cause of death worldwide and is known to be a harmful damaging host inflammatory condition, primarily caused by endotoxin released by gram-negative bacteria. Despite antibiotics administration being widely used to treat disease, effective targeted therapeutic strategies for the sepsis are still lacking. Here, we demonstrate that CM1, a derivative of natural polyphenol chrysin, exerts anti-inflammatory activity by inducing the ubiquitin-editing protein TNFAIP3 and NAD-dependent deacetylase sirtuin 1 (SIRT1). We found that CM1 attenuated Toll-like receptor 4 (TLR4)-induced the generation of inflammatory cytokines by inhibiting the extracellular-signal-regulated kinase (ERK)/MAPK and nuclear factor kappa B (NF-κB) signaling pathway. In addition, the treatment of macrophages with CM1 induced the expression of TNFAIP3 and SIRT1 in TLR4-stimulated primary macrophages, however the anti-inflammatory properties of CM1 was disappeared by siRNA silencing of TNFAPI3 or by the genetic and pharmacologic inhibition of SIRT1. Importantly, intravenously administration of CM1 resulted in the decreased susceptibility to endotoxin-induced sepsis, leading to inhibition of the generation of proinflammatory cytokines and neutrophils infiltration into lung than control mice. Collectively, these findings suggest that CM1 has the potential to be a treatment candidate for diverse inflammatory diseases including sepsis.
... Neutrophils, as the main circulating phagocytes, are the first and most abundant leukocytes that recruit at the focus of infection during sepsis. It has been proven that sepsis impairs the functioning of the immune system by causing a decrease in the innate immune response [25]. ...
Melatonin (MLT), earlier described as an effective anti-inflammatory agent, could be a beneficial adjunctive drug for sepsis treatment. This study aimed to determine the effects of MLT application in lipopolysaccharide (LPS)-induced sepsis in Wistar rats by determining the levels of liver tissue pro-inflammatory cytokines (TNF-α, IL-6) and NF-κB as well as hematological parameters indicating the state of sepsis. Additionally, an immunohistological analysis of CD14 molecule expression was conducted. Our research demonstrated that treatment with MLT prevented an LPS-induced increase in pro-inflammatory cytokines TNF-α and IL-6 and NF-κB levels, and in the neutrophil to lymphocyte ratio (NLR). On the other hand, MLT prevented a decrease in the blood lymphocyte number induced by LPS administration. Also, treatment with MLT decreased the liver tissue expression of the CD14 molecule observed after sepsis induction. In summary, in rats with LPS-induced sepsis, MLT was shown to be a significant anti-inflammatory agent with the potential to change the liver’s immunological marker expression, thus ameliorating liver function.
... Its high prevalence has made it a critical focus for healthcare professionals and researchers alike. From an epidemiological standpoint, the incidence of sepsis has been on the rise although the reasons for this increase are multifaceted [1]. Tis upward trend has been infuenced by various factors, including the aging of populations, the emergence of antibiotic-resistant pathogens, and a growing awareness and recognition of the condition [2]. ...
Sepsis, a critical medical condition instigated by infections, profoundly alters molecular and cellular immune responses. This study focused on the GSE54514 dataset obtained from the GEO database to uncover the complex gene expression patterns and related pathways in sepsis. A total of 42 genes were found to be expressed differently in septic patients compared to those of healthy individuals. The enrichment analyses of pathways revealed the disruption of natural immune pathways such as toll-like receptor signaling, regulation of actin cytoskeleton, and NOD-like receptor signaling. Through ssGSEA analysis, we revealed a strong association between sepsis and immune cell dynamics, finding significant correlations with HLA-related genes and distinct immune cell populations. Furthermore, genes such as CCL5, CD274, CD3E, and CD8A were linked with pathways, notably the “ribosome” pathway, suggesting potential roles in sepsis-related immune responses. The extensive examination provides fresh perspectives on the gene expression and pathway changes in sepsis, laying the groundwork for upcoming therapeutic interventions and a more profound comprehension of this intricate condition.
... Sepsis is currently considered to be a complex and diverse pathological process, characterized by a high degree of variability. Its clinical course is mainly affected by the type of infection, genetic factors, treatment timing, treatment methods and other uncertain factors [8]. Despite the rapid recent development and progress of anti-infective treatment regimens and organ function support technologies, mortality due to sepsis remains high [9]. ...
Background
The Surviving Sepsis Campaign (SSC) believed that early identification of septic shock, aggressive fluid resuscitation and maintenance of effective perfusion pressure should be carried out. However, some of the current research focused on a single death factor for sepsis patients, based on a limited sample, and the research results of the relationship between comorbidities and sepsis related death also have some controversies.
Method
Therefore, our study used data from a large sample of 9,544 sepsis patients aged 18–85 obtained from the MIMIC-IV database, to explore the risk factors of death in patients with sepsis. We used the general clinical information, organ dysfunction scores, and comorbidities to analyze the independent risk factors for death of these patients.
Results
The death group had significantly higher organ dysfunction scores, lower BMI, lower body temperature, faster heart rate and lower urine-output. Among the comorbidities, patients suffering from congestive heart failure and liver disease had a higher mortality rate.
Conclusion
This study helps to identify sepsis early, based on a comprehensive evaluation of a patient’s basic information, organ dysfunction scores and comorbidities, and this methodology could be used for actual clinical diagnosis in hospitals.
... Despite the advances in antibiotic therapy and intensive care medicine, sepsis still has a high mortality rate (1,6,8,18). Considering that etiological pathogenesis is complicated (7, 14) and that patients are very heterogenous regarding underlying illness, site of infection, microbiological etiology, and physiological derangement (2), it is not surprising that strategies only block each detrimental factor and that treatment with drugs that were discovered by pretreatment in a single sepsis model has been shown to have disappointing outcomes (5,9,13,16). ...
Highly purified vitamin B2 (riboflavin 5′-sodium phosphate; purity > 97%) treatment by intravenous infusion at doses above those used clinically to treat vitamin B2 deficiency showed therapeutic effects in mice not only in cases of endotoxin- and exotoxin-induced shock but also in cases of gram-negative and gram-positive bacterial infection even after the toxemia had already begun.
... Additionally, LPS serves as a crucial virulence factor known as pathogen-associated molecular pattern (PAMP) 8,9 , which typically stimulates immune cells to activate related signaling pathways, triggering the activation of related signaling pathways and causing an uncontrollable cytokine storm. These factors contribute to the development of severe sepsis with a mortality rate of 30~50% [10][11][12] . Commonly used antibiotics, such as ampicillin and polymyxin B, cannot effectively neutralize LPS 13,14 due to lack of specific binding sites and LPS modifications, and even accelerate LPS release from bacteria 15,16 . ...
Pathogenic Escherichia coli is one of the most common causes of diarrhea diseases and its characteristic component of the outer membrane-lipopolysaccharide (LPS) is a major inducer of sepsis. Few drugs have been proven to kill bacteria and simultaneously neutralize LPS toxicity. Here, the chimeric peptides-R7, A7 and G7 were generated by connecting LBP14 (LPS-targeting domain) with L7 (killing domain) via different linkers to improve antibacterial and anti-inflammatory activities. Compared to parent LBP14-RKRR and L7, the antibacterial activity of R7 with a cleavable “RKRR” linker and the “LBP14-RKRR + L7” cocktail against Escherichia coli, Salmonella typhimurium and Staphylococcus aureus was increased by 2 ~ 4-fold. Both A7 and G7 with non-cleavable linkers almost lost antibacterial activity. The ability of R7 to neutralize LPS was markedly higher than that of LBP14-RKRR and L7. In vivo, R7 could be cleaved by furin in a time-dependent manner, and release L7 and LBP14-RKRR in serum. In vivo, R7 can enhance mouse survival more effectively than L7 and alleviate lung injuries by selective inhibition of the NF-κB signaling pathways and promoting higher IAP activity. It suggests that R7 may be promising dual-function candidates as antibacterial and anti-endotoxin agents.
... This finding is consistent with previously reported results that inhibition of inflammation is beneficial in reducing lung tissue damage [34]. Acute tissue injury or viral infection can activate immune cells, and IL-1β is mainly derived from activated macrophages [35,36], and can activate neutrophils, inducing a shock-like state in animal models [37]. In addition, elevated production of IL-6 has been suggested to be stimulated by IL-1β and TNF-α, and IL-6 can also be produced by a variety of cells, including macrophages and endothelial cells [38]; moreover, circulating levels of IL-6 have been considered by many studies to be a major predictive marker of ARDS severity due to different etiologies [39,40]. ...
Acute lung injury (ALI) causes lung inflammation and edema as well as resulting in gut microbiota disorder. Probiotics, however, can improve the gut microbiota composition and modulate its immune response, playing an important role in ALI pathogenesis. Therefore, our study aims to investigate the effect of Lactobacillus reuteri on Lipopolysaccharide (LPS)-induced ALI in mice and to probe the mechanism of its synergistic modulatory effect on the lungs and intestines. We assessed the therapeutic effects of L. reuteri in the ALI mouse model by histopathology, alveolar lavage fluid and serum inflammatory factor analysis and explored microbiome and transcriptome alterations. L. reuteri intervention effectively attenuated lung tissue injury and significantly reduced the LPS-induced inflammatory response and macrophage and neutrophil infiltration. Additionally, L. reuteri improved the intestinal barrier function and remodeled the disordered microbiota. In conclusion, our study showed that L. reuteri attenuated the inflammatory response, ameliorated the pulmonary edema, repaired the intestinal barrier, and remodeled the gut microbiota in ALI mice. This study provides new perspectives on the clinical treatment of ALI.
... Systemic inflammation is the link between pancreatitis and multiple organ dysfunction (MOD) [67]. During systemic inflammatory response syndrome, activation of immune cells spreads to the whole body driving severe immunopathology [68][69][70]. DAMPs are a set of molecules which are released from the dying acinar cells and play a very important role in systemic inflammation and distant organ injury [71,72]. Most common DAMPs are highmobility group box 1 (HMGB1) protein, extracellular DNA and histones [66]. ...
Pancreatitis is an inflammatory disease, which is triggered by adverse events in acinar cells of the pancreas. After the initial injury, infiltration of neutrophils in pancreas is observed. In the initial stages of pancreatitis, the inflammation is sterile. It has been shown that the presence of neutrophils at the injury site can modulate the disease. Their depletion in experimental animal models of the acute pancreatitis has been shown to be protective. But information on mechanism of contribution to inflammation by neutrophils at the injury site is not clear. Once at injury site, activated neutrophils release azurophilic granules containing proteolytic enzymes and generate hypochlorous acid which is a strong microbicidal agent. Additionally, emerging evidence shows that neutrophil extracellular traps (NETs) are formed which consist of decondensed DNA decorated with histones, proteases and granular and cytosolic proteins. NETs are considered mechanical traps for microbes, but there is preliminary evidence to indicate that NETs, which constitute a special mechanism of the neutrophil defence system, play an adverse role in pancreatitis by contributing to the pancreatic inflammation and distant organ injury. This review presents the overall current information about neutrophils and their role including NETs in acute pancreatitis (AP). It also highlights current gaps in knowledge which should be explored to fully elucidate the role of neutrophils in AP and for therapeutic gains.
... R apid bacterial elimination is extremely important in the treatment of bacterially induced sepsis to avert the development of organ failure and mortality. 1,2 With the risk of death increasing by 7.6% every hour that initiation of treatment is delayed, it is clear that currently applied diagnosis based on blood-culturing that can take at least 10 h to several days requires more time than clinically available for therapeutic decision making. 3−5 Preliminary infection control without any identification of the causative bacterial pathogen therefore necessarily involves broad-spectrum antibiotic administration that may or may not be effective in bacterial pathogen elimination from blood. ...
Bacterially induced sepsis requires rapid bacterial detection and identification. Hours count for critically ill septic patients, while current culture-based detection requires at least 10 h up to several days. Here, we apply a microfluidic device equipped with a bacterially activated, macrophage-membrane-coating on nanowired-Si adsorbent surfaces for rapid, bacterial detection and Gram-identification in bacterially contaminated blood. Perfusion of suspensions of Gram-negative or Gram-positive bacteria through a microfluidic device equipped with membrane-coated adsorbent surfaces detected low (<10 CFU/mL) bacterial levels. Subsequent, in situ fluorescence-staining yielded Gram-identification for guiding antibiotic selection. In mixed Escherichia coli and Staphylococcus aureus suspensions, Gram-negative and Gram-positive bacteria were detected in the same ratios as those fixed in suspension. Results were validated with a 100% correct score by blinded evaluation (two observers) of 15 human blood samples, spiked with widely different bacterial strains or combinations of strains, demonstrating the potential of the platform for rapid (1.5 h in total) diagnosis of bacterial sepsis.
ABSTRAK LatarBelakang : Sepsis dan syok sepsis merupakan suatu sindroma kompleks dan multifaktorial, yang insidensi, morbiditas, dan mortalitasnya masih tinggi di dunia. Faktor-faktor yang mempengaruhi dan memperberat perjalanan penyakit sepsis diantaranya usia, jenis kelamin, fokus infeksi, skor APACHE II, skor qSOFA, jumlah leukosit, kadar hemoglobin, kadar hematokrit, jumlah trombosit, kadar glukosa, kadar albumin, kadar kreatinin serum, sistolik, denyut jantung, laju pernafasan, PaO 2 /FiO 2 , dan komorbid. Tujuan : Mengetahui faktor-faktor prediktor mortalitas sepsis dan syok sepsis Metode : Penelitian ini merupakan penelitian observasional analitik dengan metode kasus kontrol yang dilakukan mulai April-Mei 2016. Kasus adalah penderita sepsis dan syok sepsis yang meninggal setelah dirawat di ICU RSUP Dr. Kariadi, sedangkan kontrol adalah penderita sepsis dan syok sepsis yang bertahan hidup setelah dirawat di ICU atau bangsal RSUP Dr. Kariadi. Data diambil dari catatan medik pasien dan kemudian dianalisis menggunakan univariat dan bivariat dengan SPSS 21. Hasil : Pada penelitian ini didapatkan 40 pasien sebagai kasus dan 7 pasien sebagai kontrol. Setelah dilakukan uji Fisher's exact diperoleh nilai kemaknaan hubungan antara variabel dengan kematian sebagai berikut : usia (p = 0.553 [OR = 1.346]), jenis kelamin (p = 0.623 [OR = 1.091]), fokus infeksi (p = 0.285 [OR = 2.222]), skor APACHE II (p = 0.488 [OR = 2.056]), skor qSOFA (p = 0.501 [OR = 0.667]), jumlah leukosit (p = 0.291 [OR = 2.250]), kadar hemoglobin dan hematokrit (p = 0.473 [OR = 0.5]), jumlah trombosit (p = 0.574 [OR = 1.206]), kadar glukosa (p = 0.394 [OR = 1.750]), kadar albumin (p = 0.357), kadar kreatinin serum (p = 0.606 [OR = 0.831]), sistolik (p = 0.190 [OR = 3.056]), denyut jantung (p = 0.525 [OR = 0.75]), laju pernafasan (p = 0.499 [OR = 1.393]), PaO 2 /FiO 2 (p = 0.426 [OR = 1.630]), dan komorbid (p = 0.660 [OR = 0.786]). Kesimpulan : Variabel yang diteliti tidak berhubungan bermakna dengan kejadian kematian pada sepsis maupun syok sepsis. Hasil ini memiliki kelemahan berupa jumlah sampel yang sedikit sehingga tidak dapat mewakili populasi. Selain itu ada beberapa variabel lain yang diperkirakan berpotensi menjadi prediktor mortalitas sepsis maupun syok sepsis tetapi tidak diteliti karena keterbatasan data. Kata kunci : sepsis, syok sepsis, faktor prediktor kematian ABSTRACT PREDICTORS OF MORTALITY IN PATIENTS WITH SEPSIS AND SEPTIC SHOCK IN THE ICU OF KARIADI GENERAL HOSPITAL Background : Sepsis and septic shock are complex and multifactorial syndrome, which incidence, morbidity, and mortality remains high around the world. There are factors that considered to be responsible in sepsis severity, such as : age, sex, infection site, APACHE II 504
Oxidative stress (OS) develops in critically ill patients as a metabolic consequence of the immunoinflammatory and degenerative processes of the tissues. These induce increased and/or dysregulated fluxes of reactive species enhancing their pro‐oxidant activity and toxicity. At the same time, OS sustains its own inflammatory and immunometabolic pathogenesis, leading to a pervasive and vitious cycle of events that contribute to defective immunity, organ dysfunction and poor prognosis. Protein damage is a key player of these OS effects; it generates increased levels of protein oxidation products and misfolded proteins in both the cellular and extracellular environment, and contributes to forms DAMPs and other proteinaceous material to be removed by endocytosis and proteostasis processes of different cell types, as endothelial cells, tissue resident monocytes‐macrophages and peripheral immune cells. An excess of OS and protein damage in critical illness can overwhelm such cellular processes ultimately interfering with systemic proteostasis, and consequently with innate immunity and cell death pathways of the tissues thus sustaining organ dysfunction mechanisms. Extracorporeal therapies based on biocompatible/bioactive membranes and new adsorption techniques may hold some potential in reducing the impact of OS on the defective proteostasis of patients with critical illness. These can help neutralizing reactive and toxic species, also removing solutes in a wide spectrum of molecular weights thus improving proteostasis and its immunometabolic corelates. Pharmacological therapy is also moving steps forward which could help to enhance the efficacy of extracorporeal treatments. This narrative review article explores the aspects behind the origin and pathogenic role of OS in intensive care and critically ill patients, with a focus on protein damage as a cause of impaired systemic proteostasis and immune dysfunction in critical illness.
Kaempferol (KPR), a flavonoid compound found in various plants and foods, has garnered attention for its anti‐inflammatory, antioxidant, and anticancer properties. In preliminary studies, KPR can modulate several signaling pathways involved in inflammation, making it a candidate for treating cholecystitis. This study aimed to explore the effects and mechanisms of KPR on lipopolysaccharide (LPS)‐induced human gallbladder epithelial cells (HGBECs). To assess the impact of KPR on HGBECs, the HGBECs were divided into control, KPR, LPS, LPS + KPR, and LPS + UDCA groups. Cell viability and cytotoxicity were evaluated by MTT assay and lactate dehydrogenase (LDH) assay, respectively, and concentrations of KPR (10–200 μM) were tested. LPS‐induced inflammatory responses in HGBECs were to create an in vitro model of cholecystitis. The key inflammatory markers (IL‐1β, IL‐6, and TNF‐α) levels were quantified using ELISA, The modulation of the MAPK/NF‐κB signaling pathway was measured by western blot using specific antibodies against pathway components (p‐IκBα, IκBα, p‐p65, p65, p‐JNK, JNK, p‐ERK, ERK, p‐p38, and p38). The cell viability and LDH levels in HGBECs were not significantly affected by 50 μM KPR, thus it was selected as the optimal KPR intervention concentration. KPR increased the viability of LPS‐induced HGBECs. Additionally, KPR inhibited the inflammatory factors level (IL‐1β, IL‐6, and TNF‐α) and protein expression (iNOS and COX‐2) in LPS‐induced HGBECs. Furthermore, KPR reversed LPS‐induced elevation of p‐IκBα/IκBα, p‐p65/p65, p‐JNK/JNK, p‐ERK/ERK, and p‐p38/p38 ratios. KPR attenuates the LPS‐induced inflammatory response in HGBECs, possibly by inhibiting MAPK/NF‐κB signaling.
Sepsis adalah sindrom penyakit yang disebabkan oleh infeksi dan merupakan penyakit yang berdampak tinggi pada morbiditas dan mortalitas. Pemberian cairan intravena merupakan terapi mendasar dalam perawatan kritis, namun pertanyaan kunci masih belum terjawab mengenai komposisi dan dosis cairan yang optimal. Ulasan ini mengevaluasi bukti terbaru mengenai efek resusitasi cairan pada patofisiologi, fungsi organ, dan hasil klinis untuk pasien sakit kritis.
Dysregulation of liver metabolism associated with obesity during feeding and fasting leads to the breakdown of metabolic homeostasis. However, the underlying mechanism remains unknown. Here, we measured multi-omics data in the liver of wild-type and leptin-deficient obese (ob/ob) mice at ad libitum feeding and constructed a differential regulatory trans-omic network of metabolic reactions. We compared the trans-omic network at feeding with that at 16 h fasting constructed in our previous study. Intermediate metabolites in glycolytic and nucleotide metabolism decreased in ob/ob mice at feeding but increased at fasting. Allosteric regulation reversely shifted between feeding and fasting, generally showing activation at feeding while inhibition at fasting in ob/ob mice. Transcriptional regulation was similar between feeding and fasting, generally showing inhibiting transcription factor regulations and activating enzyme protein regulations in ob/ob mice. The opposite metabolic dysregulation between feeding and fasting characterizes breakdown of metabolic homeostasis associated with obesity.
Asparagi Radix is a healthy food type with medicinal and edible homology, which is now widely used for improving pulmonary inflammation in clinical. However, the lung-protective effect and the active...
Wumei pills (WMP), a classical Chinese herbal formula, have shown efficacy in the treatment of ulcerative colitis (UC) and type 2 diabetes (T2DM). However, the underlying mechanisms by which WMP simultaneously targets these distinct diseases remain unclear. In this study, a network pharmacology approach was employed to unravel the potential molecular mechanisms of WMP in UC and T2DM treatment. This analysis provides a bioinformatics foundation for the traditional Chinese medicine concept of “treating different diseases with the same treatment.” WMP was found to contain 65 active components, including flavonoids, sterols, and alkaloids, that act on 228 shared targets for UC and T2DM. Network analysis identified 5 core compounds (Quercetin, Kaempferol, beta-Sitosterol, Isocorypalmine, Stigmasterol) and 8 core proteins (AKT1, ESR1, TP53, IL6, JUN, MYC, TNF, EGFR) that play pivotal roles in the treatment of UC and T2DM by WMP. WMP exerts its therapeutic effects by modulating signaling pathways, including the NF-κB pathway, PI3K-Akt pathway, and p53 pathway. Molecular docking results indicate a strong binding affinity between core compounds and core genes. This study bridges the understanding of 2 diseases using network pharmacology and provides insights into shared therapeutic mechanisms, opening doors for further research in modern Chinese herbal formulations.
In the present study, neuroprotective effect of sevoflurane in combination with ketamine was investigated on TNF‐α induced necroptosis of neurons and cognitive impairment in the rat model. The results demonstrated that exposure to TNF‐α/z‐VAD led to a significant decrease in viability of HT‐22 neuronal cells. However, incubation of HT‐22 cells with ketamine plus sevoflurane inhibited decrease in viability induced by TNF‐α/z‐VAD exposure. The increase in production of ROS by TNF‐α/z‐VAD exposure in HT‐22 cells was effectively suppressed on pre‐treatment with ketamine plus sevoflurane. Moreover, suppression of TNF‐α/z‐VAD induced ROS production in HT‐22 cells by ketamine plus sevoflurane pretreatment was higher in comparison to ketamine or sevoflurane treatment alone. Treatment of HT‐22 cells with ketamine plus sevoflurane suppressed TNF‐α/z‐VAD induced increase in RIP1 and p‐MLKL protein expression. Ketamine plus sevoflurane treatment effectively reversed decrease in movement speed as well as total distance traveled in TNF‐α injected rats. The number of neurons in rat hippocampus injected with TNF‐α showed a significant decrease more specifically in carbonic anhydrase‐3 region. However, no significant change in the density of neurons was observed in the hippocampus of rats pretreated with ketamine plus sevoflurane by TNF‐α injection. The increase in expression of p‐MLKL and p‐RIP3 by TNF‐α injection was effectively reversed in rats on treatment with ketamine plus sevoflurane. In silico studies revealed that ketamine interacts with p‐MLKL protein in different confirmations with the binding affinities ranging from −9.7 to −8.4 kcal/mol. It was found that ketamine binds to p‐MLKL protein by interacting with alanine (ALA A:295), proline (PRO A:306), glutamine (GLN A: 307) and isoleucine (ILE A:293) amino acid residues. In summary, ketamine plus sevoflurane combination alleviates TNF‐α/z‐VAD induced decrease in viability of HT‐22 cells in vitro and rat hippocampus neurons in vivo. Moreover, ketamine plus sevoflurane combination prevented TNF‐α injection induced cognitive impairment in rats. Therefore, sevoflurane plus ketamine combination can be developed as a potential therapeutic regimen for treatment of isoflurone induced cognitive impairment.
N-(E)-p-Coumaroyl tyrosine is a phenolic amino acid derivative extracted from the Abrus mollis Hance, Syn of Abrus melanospermus subsp. melanospermus, Fabaceae, which has anti-inflammatory activity. In this study, we aimed to investigate the inflammatory activity and mechanism of N-(E)-p-coumaroyl tyrosine by establishing a lipopolysaccharide-stimulated RAW 264.7 cells in vitro and an injured zebrafish tail fin in vivo. The results showed that N-(E)-p-coumaroyl tyrosine decreased the levels of ROS, NO, IL-6, IL-1β, and IL-18 secreted by LPS-induced RAW 264.7 macrophages. In addition, the results of in vivo studies showed that it inhibited the aggregation of neutrophils and macrophages to the tail after tail cutting stimulation. In summary, N-(E)-p-coumaroyl tyrosine inhibited the production of NO and ROS; decreased the secretions of IL-6, IL-1β, and IL-18; and reduced the aggregation of zebrafish neutrophils and macrophages. Therefore, N-(E)-p-coumaroyl tyrosine may be developed as a potential therapeutic option for inflammatory diseases.
Understanding the anatomy and physiology of the peritoneum has a direct effect on the outcome of medical therapy and laparoscopic surgery. The structural organization of the peritoneum, the characteristics of the peritoneal cavity, and the composition and extent of the contained peritoneal fluid pave the path for new discoveries in diagnostic strategies, drug delivery methodologies, and refinement of surgical procedures. The enormous surface area of the peritoneum, and the presence of interconnected greater and lesser peritoneal sacs and recesses in the upper and lower abdomen may render exploration of the extent of cancer dissemination a complicated process, but at the same time present the opportunity to devise effective therapeutic measures that counter inflammatory process and limit dissemination of cancerous cells. Knowledge of the topography, relationships of intra- and retroperitoneal organs, cytoarchitecture of mesothelial cells, and regional variations is likely to enhance focused therapy, reduce postoperative complications, hospital stay, and associated economic cost. Corollary to this, the size, distribution, and the chemical composition of the normal peritoneal fluid allow practitioners to rapidly correlate abnormal findings to disease processes. The nature and site of pain elicited by peritoneal irritation due to localized or generalized pathologic processes may be in the form of a sharp and well-defined or diffuse, dull, and aching pain depending on diseased peritoneal region and stimulated nerves. Hematogenous, lymphatic, or exudative contents of the peritoneal cavity may indicate traumatic injury or inflammatory process that presents rebound tenderness and rigidity.
Maintenance of homeostasis of the peritoneal cavity requires a stable chemical composition of the peritoneal fluid, an optimum temperature, and relative humidity. This way, viscosity of the peritoneal fluid hand and hypothermia are controlled by limiting evaporation and eliminating desiccation. Further, preserving this peritoneal milieu can eliminate cellular inflammation and stress, and reduce pain by blocking the release of immune reactive substances related to cell injury and disruption. In view of the above, preserving moisture on peritoneal surfaces during surgical procedures contributes to a normal physiologic setting and ultimately hastens patient’s recovery.
Cellular homeostasis is lost or becomes dysfunctional during septic shock due to the activation of the inflammatory response and the deregulation of oxidative stress. Antioxidant therapy administered alongside standard treatment could restore this lost homeostasis. We included 131 patients with septic shock who were treated with standard treatment and vitamin C (Vit C), vitamin E (Vit E), N-acetylcysteine (NAC), or melatonin (MT), in a randomized trial. Organ damage quantified by Sequential Organ Failure Assessment (SOFA) score, and we determined levels of Interleukins (IL) IL1β, Tumor necrosis factor alpha (TNFα), IL-6, monocyte chemoattractant protein-1 (MCP-1), Transforming growth factor B (TGFβ), IL-4, IL-10, IL-12, and Interferon-γ (IFNγ). The SOFA score decreased in patients treated with Vit C, NAC, and MT. Patients treated with MT had statistically significantly reduced of IL-6, IL-8, MCP-1, and IL-10 levels. Lipid peroxidation, Nitrates and nitrites (NO3− and NO2−), glutathione reductase, and superoxide dismutase decreased after treatment with Vit C, Vit E, NAC, and MT. The levels of thiols recovered with the use of Vit E, and all patients treated with antioxidants maintained their selenium levels, in contrast with controls (p = 0.04). The findings regarding oxidative stress markers and cytokines after treatment with antioxidants allow us to consider to future the combined use of antioxidants in a randomized clinical trial with a larger sample to demonstrate the reproducibility of these beneficial effects.
Dysregulation of liver metabolism associated with obesity during feeding and fasting leads to the breakdown of metabolic homeostasis. However, the underlying mechanism remains unknown. Here, we measured multi-omics data in the liver of wild-type and leptin-deficient obese (ob/ob) mice at ad libitum feeding, and constructed a differential regulatory trans-omic network of metabolic reactions. We compared the trans-omic network at feeding with that at 16 h-fasting constructed in our previous study. Intermediate metabolites in glycolytic and nucleotide metabolism decreased in ob/ob mice at feeding but increased at fasting. Allosteric regulation reversely shifted between feeding and fasting, generally showing activation at feeding while inhibition at fasting in ob/ob mice. Transcriptional regulation was similar between feeding and fasting, generally showing inhibiting transcription factor regulations, activating enzyme protein regulations in ob/ob mice. The opposite metabolic dysregulation between feeding and fasting characterizes breakdown of metabolic homeostasis associated with obesity.
Background
Disseminated Intravascular Coagulation (DIC) is a syndrome of dysregulated coagulation. Patients with sepsis are at increased risk for DIC. HMG-CoA Reductase Inhibitors (Statins) are primarily used as lipid-lowering agents; however, studies have suggested statins may possess anti-inflammatory, antithrombotic, anticoagulant, and endothelial stabilizing properties. These mechanisms may oppose those that underlie the pathogenesis of septic DIC.
Methods
To evaluate whether statins may be protective against the development of DIC, we conducted a multi-center, retrospective case-control study where 86,638 critically ill patients admitted to the ICU with sepsis, severe sepsis or septic shock were identified during a 3-year period. Patients who developed DIC during their hospitalization were identified and stratified by whether they received a statin or not during their hospitalization. Odds ratios for development of DIC was calculated by composite of any statin, as well as low, moderate, and high intensity statins.
Results
2236 patients would develop DIC compared to 84,402 who did not. The use of any statin was associated with a reduced likelihood for developing DIC (odds ratio [OR], 0.69; 95% CI, 0.61–0.78). This was observed with use of both moderate (OR, 0.64; 95% CI, 0.53–0.77) and high (OR, 0.72; 95% CI, 0.61–0.84) but not low intensity statins (OR, 0.84; 95% CI, 0.53–1.32).
Conclusions
The use of moderate and high intensity statins was associated with a significantly reduced odds of developing DIC in critically ill patients with sepsis. This present study may be the first to suggest that statin medications may independently reduce the frequency of DIC in critically ill patients with severe sepsis or septic shock. More research is needed to investigate the potential for this class of medication to be protective against DIC.
Background
We explored the efficacy and main biological mechanism of geniposide intervention in sepsis.
Methods
A sepsis model was established in male BALB/c mice through cecal ligation and puncture (CLP). Different doses of geniposide (20 or 40 mg/kg) were administered intravenously at 0 and/or 24 h after CLP surgery. The survival rate of different groups was observed. Additionally, the expression levels of CD16 and MHC-II in monocytes were assessed using flow cytometry. The concentration of TNF-α, IL-1β, IL-6, and IL-10 in the serum were measured by ELISA. We also observed the biological effects of geniposide on CD16 and MHC-II expression levels in RAW264.7 cells, as well as the secretion of TNF-α, IL-1β, IL-6, and IL-10, in the LPS-induced RAW264.7 cell model. The PPARγ levels were determined using western blot analysis.
Results
Intravenous administration of 40 mg/kg of geniposide at 0 h after CLP significantly improved the survival outcomes in the septic mouse model, with no significant benefits from low dosing (20 mg/kg) or delayed administration (24 h). The effective dose of geniposide significantly decreased the serum cytokine TNF-α, IL-1β, IL-6, and IL-10 concentrations in septic mice ( P < 0.05). Notably, in vitro assays showed that geniposide specifically increased the IL-10 level. Geniposide significantly reduced the CD16 expression ( P < 0.05) and increased MHC-II expression in monocytes ( P < 0.05). Additionally, geniposide elevated the PPARγ level in monocytes ( P < 0.05).
Conclusions
High-dose early-stage geniposide administration significantly improved the survival rate in a CLP mouse sepsis model by modulating the monocyte phenotype and regulating the cytokine network (IL-6/IL-10 levels). The pharmacological mechanism of geniposide action might be exerted primarily through PPARγ upregulation.
Bacterial sepsis is a life-threatening condition caused by bacteria entering the bloodstream and triggering an immune response, underscoring the importance of early recognition and prompt treatment. Nanomedicine holds promise for addressing sepsis through improved diagnostics, nanoparticle biosensors for detection and imaging, enhanced antibiotic delivery, combating resistance, and immune modulation. However, challenges remain in ensuring safety, regulatory compliance, scalability, and cost-effectiveness before clinical implementation. Further research is needed to optimize design, efficacy, safety, and regulatory strategies for effective utilization of nanomedicines in bacterial sepsis diagnosis and treatment. This review highlights the significant potential of nanomedicines, including improved drug delivery, enhanced diagnostics, and immunomodulation for bacterial sepsis. It also emphasizes the need for further research to optimize design, efficacy, safety profiles, and address regulatory challenges to facilitate clinical translation.
Sepsis is an abnormally dysregulated immune response against infection in which the human immune system ranges from a hyper-inflammatory phase to an immune-suppressive phase. Current assessment methods are limiting owing to time-consuming and laborious sample preparation protocols. We propose a rapid label-free imaging-based technique to assess the immune status of individual human monocytes. High-resolution intracellular compositions of individual monocytes are quantitatively measured in terms of the three-dimensional distribution of refractive index values using holotomography, which are then analyzed using machine-learning algorithms to train for the classification into three distinct immune states: normal, hyper-inflammation, and immune suppression. The immune status prediction accuracy of the machine-learning holotomography classifier was 83.7% and 99.9% for one and six cell measurements, respectively. Our results suggested that this technique can provide a rapid deterministic method for the real-time evaluation of the immune status of an individual.
N-(E)-p-coumaroyl tyrosine (NPCT) is a phenolic amino acid derivative extracted from the Leguminosae Abrus Mollis Hance which has anti-inflammatory activity. In this study, we aimed to investigate the inflammatory activity and mechanism of NPCT by establishing a lipopolysaccharide (LPS)-stimulated RAW264.7 cells in vitro and an injured zebrafish tail fin in vivo. The results showed that NPCT decreased the levels of ROS, NO, IL-6, IL-1β, and IL-18 secreted by LPS-induced RAW 264.7 macrophages. In addition, the results of in vivo studies showed that it inhibited the aggregation of neutrophils and macrophages to the tail after tail cutting stimulation. In summary, NPCT inhibited the production of NO and ROS, decreased the secretions of IL-6, IL-1β, and IL-18, and reduced the aggregation of zebrafish neutrophils and macrophages. Therefore, NPCT may be developed as a potential therapeutic option for inflammatory diseases.
Lipopolysaccharide (LPS)-induced acute kidney injury (AKI) is characterized by inflammation and infiltration of immune cells, mainly neutrophils and macrophages, and results in sudden renal dysfunction. Previously, we have reported the anti-inflammatory and renoprotective role of angiotensin-II type-2 receptor (AT2R), expressed on kidney tubular cells and immune cells, in LPS-induced AKI. Moreover, in vitro studies revealed macrophage AT2R activation shifts the cells to the anti-inflammatory M2 subtype. However, the protective role of the macrophage AT2R in a model of AKI is unknown. The present study addressed this question by adoptive transfer of bone marrow-derived macrophages (BMDMs) in systemically macrophage-depleted mice. We acquired significant systemic macrophage depletion by two doses of liposomal clodronate, and the mice were repopulated with BMDMs (CD11b+F4/80+, double positive) primed with AT2R agonist C21 (CLD+MacC21+LPS) or vehicle (CLD+Mac+LPS) in vitro for 60 min, followed by LPS (5 mg/kg body weight, intraperitoneal) challenge. We observed a gradual increase in the CD11b+ cells 2 hr and 24 hr after the LPS challenge. However, kidney CD11b+ cells in CLD+Mac+LPS group were elevated as compared to CLD+MacC21+LPS 2 hr after the LPS challenge. The level of inflammatory cytokine (TNF-α) was elevated at 2 hr, which was reduced significantly in CLD+MacC21+LPS treated animals. Also, CLD+MacC21+LPS treated animals had elevated plasma and renal IL-10, indicating an anti-inflammatory role of C21-treated BMDMs. Renal functional injury in CLD+MacC21+LPS treated animals was partially improved. Collectively, the data demonstrates that BMDM AT2R stimulation results in anti-inflammation and partial renoprotection against early stages of LPS-induced AKI.
Endotoxin, a constituent of Gram-negative bacteria, stimulates macrophages to release large quantities of tumor necrosis factor
(TNF) and interleukin-1 (IL-1), which can precipitate tissue injury and lethal shock (endotoxemia). Antagonists of TNF and
IL-1 have shown limited efficacy in clinical trials, possibly because these cytokines are early mediators in pathogenesis.
Here a potential late mediator of lethality is identified and characterized in a mouse model. High mobility group–1 (HMG-1)
protein was found to be released by cultured macrophages more than 8 hours after stimulation with endotoxin, TNF, or IL-1.
Mice showed increased serum levels of HMG-1 from 8 to 32 hours after endotoxin exposure. Delayed administration of antibodies
to HMG-1 attenuated endotoxin lethality in mice, and administration of HMG-1 itself was lethal. Septic patients who succumbed
to infection had increased serum HMG-1 levels, suggesting that this protein warrants investigation as a therapeutic target.
Hyperglycemia and insulin resistance are common in critically ill patients, even if they have not previously had diabetes. Whether the normalization of blood glucose levels with insulin therapy improves the prognosis for such patients is not known.
We performed a prospective, randomized, controlled study involving adults admitted to our surgical intensive care unit who were receiving mechanical ventilation. On admission, patients were randomly assigned to receive intensive insulin therapy (maintenance of blood glucose at a level between 80 and 110 mg per deciliter [4.4 and 6.1 mmol per liter]) or conventional treatment (infusion of insulin only if the blood glucose level exceeded 215 mg per deciliter [11.9 mmol per liter] and maintenance of glucose at a level between 180 and 200 mg per deciliter [10.0 and 11.1 mmol per liter]).
At 12 months, with a total of 1548 patients enrolled, intensive insulin therapy reduced mortality during intensive care from 8.0 percent with conventional treatment to 4.6 percent (P<0.04, with adjustment for sequential analyses). The benefit of intensive insulin therapy was attributable to its effect on mortality among patients who remained in the intensive care unit for more than five days (20.2 percent with conventional treatment, as compared with 10.6 percent with intensive insulin therapy, P=0.005). The greatest reduction in mortality involved deaths due to multiple-organ failure with a proven septic focus. Intensive insulin therapy also reduced overall in-hospital mortality by 34 percent, bloodstream infections by 46 percent, acute renal failure requiring dialysis or hemofiltration by 41 percent, the median number of red-cell transfusions by 50 percent, and critical-illness polyneuropathy by 44 percent, and patients receiving intensive therapy were less likely to require prolonged mechanical ventilation and intensive care.
Intensive insulin therapy to maintain blood glucose at or below 110 mg per deciliter reduces morbidity and mortality among critically ill patients in the surgical intensive care unit.
Streptococcal mitogenic exotoxin Z (SMEZ), a superantigen derived from Streptococcus pyogenes, provoked expansion of human lymphocytes expressing the Vβ 2, 4, 7 and 8 motifs of T-cell receptor. SMEZ was pyrogenic in
rabbits and stimulated the expression of the T-cell activation markers CD69 and cutaneous lymphocyte-associated antigen. A
variety of cytokines was released by human mononuclear leukocytes stimulated with SMEZ, which was 10-fold more active than
streptococcal pyrogenic exotoxin A. Th2-derived cytokines were elicited only by superantigens and not by streptococcal cells.
The recent discovery of the mode of interaction between a group of microbial proteins known as superantigens and the immune system has opened a wide area of investigation into the possible role of these molecules in human diseases. Superantigens produced by certain viruses and bacteria, including Mycoplasma species, are either secreted or membrane-bound proteins. A unique feature of these proteins is that they can interact simultaneously with distinct receptors on different types of cells, resulting in enhanced cell-cell interaction and triggering a series of biochemical reactions that can lead to excessive cell proliferation and the release of inflammatory cytokines. However, although superantigens share many features, they can have very different biological effects that are potentiated by host genetic and environmental factors. This review focuses on a group of secreted pyrogenic toxins that belong to the superantigen family and highlights some of their structural-functional features and their roles in diseases such as toxic shock and autoimmunity. Deciphering the biological activities of the various superantigens and understanding their role in the pathogenesis of microbial infections and their sequelae will enable us to devise means by which we can intervene with their activity and/or manipulate them to our advantage.
Glucocorticoid hormones are important for vital functions and act to modulate inflammatory and immune responses. Yet, in contrast to other hormonal systems, no endogenous mediators have been identified that can directly counter-regulate their potent anti-inflammatory and immunosuppressive properties. Recent investigations of the protein macrophage migration inhibitory factor (MIF), which was discovered originally to be a T-lymphocyte-derived factor, have established it to be a pro-inflammatory pituitary and macrophage cytokine and a critical mediator of septic shock. Here we report the unexpected finding that low concentrations of glucocorticoids induce rather than inhibit MIF production from macrophages. MIF then acts to override glucocorticoid-mediated inhibition of cytokine secretion by lipopolysaccharide (LPS)-stimulated monocytes and to overcome glucocorticoid protection against lethal endotoxaemia. These observations identify a unique counter-regulatory system that functions to control inflammatory and immune responses.
To review new insights in the pathogenetic mechanisms involved in the development of disseminated intravascular coagulation (DIC) in septic patients, in order to develop new directions for therapeutic intervention.
Articles and published peer-reviewed abstracts on the mechanism of the initiation of DIC in sepsis.
Studies selected for detailed review were those reporting specifics about the mechanism of activation of coagulation and fibrinolysis in experimental human and animal models of sepsis. Data extraction guidelines for assessing data quality included validity of the model, quality of the laboratory assessment of activation of coagulation and fibrinolysis, and methodological considerations, such as the presence of control experiments and statistical analysis.
After the presence of endotoxin in the circulation, significant coagulation activation can be detected. This activation is preceded by an increase in the serum levels of various cytokines, such as tumor necrosis factor and interleukins. Inhibition of the increase in tumor necrosis factor results in inhibition of coagulation activation. Measurement of molecular markers for the activation of coagulation proteins at various levels indicates that the activation of coagulation is mediated by the tissue factor-dependent pathway, which is further confirmed by experiments in which the inhibition of the tissue factor-dependent pathway resulted in complete inhibition of coagulation activation. The activation of coagulation seems to be amplified by impaired function of the protein C-protein S inhibitory pathway. An imbalance between coagulation and fibrinolysis, ultimately leading to plasminogen activator inhibitor type 1-mediated inhibition of fibrinolysis, may further promote the procoagulant state.
The increased knowledge of the various pathogenetic mechanisms of coagulation activation and fibrinolysis in sepsis may have therapeutic implications; however, their efficacy needs to be assessed in appropriate clinical trials.
Lipopolysaccharide (LPS), residing in the outer membrane of all gram-negative bacteria, is considered a major initiating factor of the gram-negative septic shock syndrome in humans. LPS forms a complex with the LPS binding protein (LBP) in plasma, and LPS-LBP complexes engage a specific receptor, CD14, on the surface of myeloid cells, leading to the production of potent proinflammatory cytokines. The major goal of this study was to test the importance of the CD14 pathway in vivo in a primate model that is similar to human septic shock. Primates were pretreated with one of two different inhibitory anti-CD14 mAbs, then challenged with intravenous endotoxin (375 microg/kg/h) for 8 h. The anti-CD14 treatment regimens were successful in preventing profound hypotension, reducing plasma cytokine levels (TNF-alpha, IL-1beta, IL-6, and IL-8), and inhibiting the alteration in lung epithelial permeability that occurred in animals treated with LPS and an isotype-matched control antibody. These results demonstrate for the first time the importance of the CD14 pathway in a primate model that is similar to human septic shock. Inhibition of the CD14 pathway represents a novel therapeutic approach to treating this life-threatening condition.
Lipopolysaccharide binding protein (LBP) is a plasma protein known to facilitate the diffusion of bacterial LPS (endotoxin). LBP catalyzes movement of LPS monomers from LPS aggregates to HDL particles, to phospholipid bilayers, and to a binding site on a second plasma protein, soluble CD14 (sCD14). sCD14 can hasten transfer by receiving an LPS monomer from an LPS aggregate, and then surrendering it to an HDL particle, thus acting as a soluble "shuttle" for an insoluble lipid. Here we show that LBP and sCD14 shuttle not only LPS, but also phospholipids. Phosphatidylinositol (PI), phosphatidylcholine, and a fluorescently labeled derivative of phosphatidylethanolamine (R-PE) are each transferred by LBP from membranes to HDL particles. The transfer could be observed using recombinant LBP and sCD14 or whole human plasma, and the plasma-mediated transfer of PI could be blocked by anti-LBP and partially inhibited by anti-CD14. sCD14 appears to act as a soluble shuttle for phospholipids since direct binding of PI and R-PE to sCD14 was observed and because addition of sCD14 accelerated transfer of these lipids. These studies define a new function for LBP and sCD14 and describe a novel mechanism for the transfer of phospholipids in blood. In further studies, we show evidence suggesting that LBP transfers LPS and phospholipids by reciprocal exchange: LBP-catalyzed binding of R-PE to LPS x sCD14 complexes was accompanied by the exit of LPS from sCD14, and LBP-catalyzed binding of R-PE to sCD14 was accelerated by prior binding of LPS to sCD14. Binding of one lipid is thus functionally coupled with the release of a second. These results suggest that LBP acts as a lipid exchange protein.
Mutations of the gene Lps selectively impede lipopolysaccharide (LPS) signal transduction in C3H/HeJ and C57BL/10ScCr mice, rendering them resistant
to endotoxin yet highly susceptible to Gram-negative infection. The codominantLps
d allele of C3H/HeJ mice was shown to correspond to a missense mutation in the third exon of the Toll-like receptor-4 gene
(Tlr4), predicted to replace proline with histidine at position 712 of the polypeptide chain. C57BL/10ScCr mice are homozygous
for a null mutation of Tlr4. Thus, the mammalian Tlr4 protein has been adapted primarily to subserve the recognition of LPS and presumably transduces
the LPS signal across the plasma membrane. Destructive mutations of Tlr4 predispose to the development of Gram-negative sepsis, leaving most aspects of immune function intact.
To study the biologic role of migration inhibitory factor (MIF), a pleiotropic cytokine, we generated a mouse strain lacking MIF by gene targeting in embryonic stem cells. Analysis of the role of MIF during sepsis showed that MIF-/- mice were resistant to the lethal effects of high dose bacterial lipopolysaccharide (LPS), or Staphylococcus aureus enterotoxin B (SEB) with D-galactosamine and had lower plasma levels of tumor necrosis factor alpha (TNF-alpha) than did wild-type mice, but normal levels of interleukin (IL)-6 and IL-10. When stimulated with LPS and interferon gamma, macrophages from MIF-/- mice showed diminished production of TNF-alpha, normal IL-6 and IL-12, and increased production of nitric oxide. MIF-/- animals cleared gram-negative bacteria Pseudomonas aeruginosa instilled into the trachea better than did wild-type mice and had diminished neutrophil accumulation in their bronchoalveolar fluid compared to the wild-type mice. Thioglycollate elicited peritoneal exudates in uninfected MIF-/- mice, but showed normal neutrophil accumulation. Finally, the findings of enhanced resistance to P. aeruginosa and resistance to endotoxin-induced lethal shock suggest that the counteraction or neutralization of MIF may serve as an adjunct therapy in sepsis.
The peptidoglycan of Gram-positive bacteria is known to trigger cytokine release from peripheral blood mononuclear cells (PBMCs). However, it requires 100-1000 times more Gram-positive peptidoglycan than Gram-negative lipopolysaccharide to release the same amounts of cytokines from target cells. Thus, either peptidoglycan is poorly active or only part of it is required for PBMC activation. To test this hypothesis, purified Streptococcus pneumoniae walls were digested with their major autolysin N-acetylmuramoyl-L-alanine amidase, and/or muramidase. Solubilized walls were separated by reverse phase high pressure chromatography. Individual fractions were tested for their PBMC-stimulating activity, and their composition was determined. Soluble components had a Mr between 600 and 1500. These primarily comprised stem peptides cross-linked to various extents. Simple stem peptides (Mr <750) were 10-fold less active than undigested peptidoglycan. In contrast, tripeptides (Mr >1000) were >/=100-fold more potent than the native material. One dipeptide (inactive) and two tripeptides (active) were confirmed by post-source decay analysis. Complex branched peptides represented </=2% of the total material, but their activity (w/w) was almost equal to that of LPS. This is the first observation suggesting that peptidoglycan stem peptides carry high tumor necrosis factor-stimulating activity. These types of structures are conserved among Gram-positive bacteria and will provide new material to help elucidate the mechanism of peptidoglycan-induced inflammation.
Toll-like receptor 4 (TLR4) is a mammalian homologue of Drosophila Toll, a leucine-rich repeat molecule that can trigger innate responses against pathogens. The TLR4 gene has recently been shown to be mutated in C3H/HeJ and C57BL/10ScCr mice, both of which are low responders to lipopolysaccharide (LPS). TLR4 may be a long-sought receptor for LPS. However, transfection of TLR4 does not confer LPS responsiveness on a recipient cell line, suggesting a requirement for an additional molecule. Here, we report that a novel molecule, MD-2, is requisite for LPS signaling of TLR4. MD-2 is physically associated with TLR4 on the cell surface and confers responsiveness to LPS. MD-2 is thus a link between TLR4 and LPS signaling. Identification of this new receptor complex has potential implications for understanding host defense, as well as pathophysiologic, mechanisms.
Sepsis induces extensive lymphocyte apoptosis, a process which may be beneficial to host survival by down-regulating the inflammatory response or, alternatively, harmful by impairing host defenses. To determine the beneficial vs. adverse effects of lymphocyte apoptosis in sepsis, we blocked lymphocyte apoptosis either by N-benzyloxycarbonyl-Val-Ala-Asp(O-methyl) fluoromethyl ketone (z-VAD), a broad-spectrum caspase inhibitor, or by use of Bcl-2 Ig transgenic mice that selectively overexpress the antiapoptotic protein Bcl-2 in a lymphoid pattern. Both z-VAD and Bcl-2 prevented lymphocyte apoptosis and resulted in a marked improvement in survival. z-VAD did not decrease lymphocyte tumor necrosis factor-alpha production. Considered together, these two studies employing different methods of blocking lymphocyte apoptosis provide compelling evidence that immunodepression resulting from the loss of lymphocytes is a central pathogenic event in sepsis, and they challenge the current paradigm that regards sepsis as a disorder resulting from an uncontrolled inflammatory response. Caspase inhibitors may represent a treatment strategy in this highly lethal disorder.
The interleukin-1 (IL-1) receptor/Toll-like receptor (TLR) superfamily is a recently defined and expanding group of receptors that participate in host responses to injury and infection. The superfamily is defined by the Toll/IL-1 receptor (TIR) domain, which occurs in the cytosolic region of family members, and is further subdivided into two groups based on homology to either the Type I IL-1 receptor or Drosophila Toll receptor extracellular domain. The former group includes the receptor for the important Th1 cytokine IL-18, and T1/ST2, which may have a role in Th2 cell function. The latter group includes six mammalian TLRs, including TLR2 and TLR4, that largely mediate the host response to gram-positive and gram-negative bacteria, respectively. Whether bacterial products are actual ligands for TLRs, or whether they generate ligands via as yet unidentified pattern recognition receptors, has yet to be determined. Signaling pathways activated via the TIR domain trigger the activation of downstream kinases, and transcription factors such as NF-kappaB, and involve the adaptor protein MyD88, which itself contains a TIR domain.
We have identified new activating receptors of the Ig superfamily expressed on human myeloid cells, called TREM (triggering receptor expressed on myeloid cells). TREM-1 is selectively expressed on blood neutrophils and a subset of monocytes and is up-regulated by bacterial LPS. Engagement of TREM-1 triggers secretion of IL-8, monocyte chemotactic protein-1, and TNF-alpha and induces neutrophil degranulation. Intracellularly, TREM-1 induces Ca2+ mobilization and tyrosine phosphorylation of extracellular signal-related kinase 1 (ERK1), ERK2 and phospholipase C-gamma. To mediate activation, TREM-1 associates with the transmembrane adapter molecule DAP12. Thus, TREM-1 mediates activation of neutrophil and monocytes, and may have a predominant role in inflammatory responses.
We have examined the ability of peptidoglycan (PepG) and lipoteichoic acid (LTA) isolated from Staphylococcus aureus to induce the release of tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), and IL-10 in whole human blood and identified the cellular origins of these cytokines. Both PepG and LTA induced transient increases in TNF-alpha and IL-10 in plasma, with peak values at 6 and 12 h, respectively. IL-6 values increased throughout the experimental period (24 h). The TNF-alpha, IL-6, and IL-10 release induced by PepG and LTA was dose dependent. Only PepG was a potent inducer of TNF-alpha secretion. After stimulation of whole blood with PepG or LTA, very pure populations of monocytes (CD14 positive), T cells (CD2 positive), B cells (CD19 positive), and granulocytes (CD15 positive) were isolated by immunomagnetic separation and analyzed by reverse transcription-PCR for mRNA transcripts encoding TNF-alpha, IL-6, and IL-10. The TNF-alpha mRNA results were inconclusive. In contrast, PepG induced IL-6 and IL-10 mRNA accumulation in both T cells and monocytes. LTA, as well as lipopolysaccharide, induced IL-6 and IL-10 mRNA production in monocytes and possibly in T cells. Whether granulocytes and B cells produce cytokines in response to bacterial stimuli remains obscure. Blockade of the CD14 receptors with monoclonal antibodies (18D11) had no influence on the PepG-induced release of TNF-alpha but attenuated the LTA-induced release of the same cytokine. In conclusion, our data indicate that circulating T cells and monocytes contribute to cytokine production in sepsis caused by gram-positive bacteria.
The innate immune response is the first line of defence against infectious disease. The principal challenge for the host is to detect the pathogen and mount a rapid defensive response. A group of proteins that comprise the Toll or Toll-like family of receptors perform this role in vertebrate and invertebrate organisms. This reflects a remarkable conservation of function and it is therefore not surprising that studies of the mechanism by which they act has revealed new and important insights into host defence.
The toll-like receptor 2 (TLR2) has gained importance as a major mammalian receptor for lipoproteins derived from the cell
wall of a variety of bacteria, such as Borrelia burgdorferi,Treponema pallidum, and Mycoplasma fermentans. We were interested in identifying mutations in the TLR2 gene that might prove to be associated with altered susceptibility
to septic shock. We performed a mutation screen of the TLR2 gene using single-stranded conformational polymorphism in 110
normal, healthy study subjects and detected an Arg753Gln mutation in three individuals. No other missense mutations were detected
in the TLR2 open reading frame. Functional studies demonstrate that the Arg753Gln polymorphism, in comparison to the wild-type
TLR2 gene, is significantly less responsive to bacterial peptides derived from B. burgdorferi and T. pallidum. In a septic shock population, the Arg753Gln TLR2 polymorphism occurred in 2 out of 91 septic patients. More importantly,
both of the subjects with the TLR2 Arg753Gln polymorphism had staphylococcal infections. These findings suggest that a mutation
in the TLR2 gene may predispose individuals to life-threatening bacterial infections.
The recent discovery of the mode of interaction between a group of microbial proteins known as superantigens and the immune system has opened a wide area of investigation into the possible role of these molecules in human diseases. Superantigens produced by certain viruses and bacteria, including Mycoplasma species, are either secreted or membrane-bound proteins. A unique feature of these proteins is that they can interact simultaneously with distinct receptors on different types of cells, resulting in enhanced cell-cell interaction and triggering a series of biochemical reactions that can lead to excessive cell proliferation and the release of inflammatory cytokines. However, although superantigens share many features, they can have very different biological effects that are potentiated by host genetic and environmental factors. This review focuses on a group of secreted pyrogenic toxins that belong to the superantigen family and highlights some of their structural-functional features and their roles in diseases such as toxic shock and autoimmunity. Deciphering the biological activities of the various superantigens and understanding their role in the pathogenesis of microbial infections and their sequelae will enable us to devise means by which we can intervene with their activity and/or manipulate them to our advantage.
Sepsis and its sequelae are still a major cause of morbidity and mortality on today's intensive care units. The evidence that endogenous mediators actually mediate the individual's response to infection has led to various approaches to assess the individual's contribution to the course of the disease. The role of an individual's genetic background and predisposition for the extent of inflammatory responses is determined by variabilities of genes encoding endogenous mediators that constitute the pathways of inflammation. Primary responses in inflammation are mediated by proinflammatory cytokines such as tumor necrosis factor and interleukin I. Conversely, antiinflammatory mediators are released and may induce a state of immunosuppression in sepsis. Pro- and anti-inflammatory responses contribute to the outcome of patients with systemic inflammation and sepsis. Therefore, all genes encoding proteins involved in the transduction of inflammatory processes are candidate genes to determine the human genetic background that is responsible for interindividual differences in systemic inflammatory responses to injury. The genetically determined capacity of cytokine production and release, heat shock protein expression, nitric oxide synthase activity, gene polymorphisms of coagulation factors or factors of the innate immune system-like defensins, and other genes involved in inflammation may contribute to a wide range of clinical manifestations of an inflammatory disease. Genomic information may be used to identify groups of patients with a high risk of developing severe sepsis and multiple organ dysfunction, and determining which patients will benefit from antimediator strategies because of their genetic determination to high cytokine release in the inflammatory response will be the subject of future trials.
High-mobility group-1 (HMG-1), an abundant, highly conserved cellular protein, is widely known as a nuclear DNA-binding protein that stabilizes nucleosome formation, facilitates gene transcription, and regulates the activity of steroid hormone receptors. We discovered that HMG-1 is a late mediator of delayed endotoxin lethality. When released by activated monocytes, it participates in the development of lethality and it activates downstream cytokine release. This review covers the general features of HMG-1 and its newly appreciated role as a cytokine.
Cells undergoing programmed cell death (apoptosis) are cleared rapidly in vivo by phagocytes without inducing inflammation. Here we show that the glycosylphosphatidylinositol-linked plasma-membrane glycoprotein CD14 on the surface of human macrophages is important for the recognition and clearance of apoptotic cells. CD14 can also act as a receptor that binds bacterial lipopolysaccharide (LPS), triggering inflammatory responses. Overstimulation of CD14 by LPS can cause the often fatal toxic-shock syndrome. Here we show that apoptotic cells interact with CD14, triggering phagocytosis of the apoptotic cells. This interaction depends on a region of CD14 that is identical to, or at least closely associated with, a region known to bind LPS. However, apoptotic cells, unlike LPS, do not provoke the release of pro-inflammatory cytokines from macrophages. These results indicate that clearance of apoptotic cells is mediated by a receptor whose interactions with 'non-self' components (LPS) and 'self' components (apoptotic cells) produce distinct macrophage responses.
Objective: To determine the incidence, cost, and outcome of severe sepsis in the United States.
Design: Observational cohort study.
Setting: All nonfederal hospitals (n = 847) in seven U.S. states.
Patients: All patients (n = 192,980) meeting criteria for severe sepsis based on the International Classification of Diseases, Ninth Revision, Clinical Modification.
Interventions: None.
Measurements and Main Results : We linked all 1995 state hospital discharge records (n = 6,621,559) from seven large states with population and hospital data from the U.S. Census, the Centers for Disease Control, the Health Care Financing Administration, and the American Hospital Association. We defined severe sepsis as documented infection and acute organ dysfunction using criteria based on the International Classification of Diseases, Ninth Revision, Clinical Modification. We validated these criteria against prospective clinical and physiologic criteria in a subset of five hospitals. We generated national age- and gender-adjusted estimates of incidence, cost, and outcome. We identified 192,980 cases, yielding national estimates of 751,000 cases (3.0 cases per 1,000 population and 2.26 cases per 100 hospital discharges), of whom 383,000 (51.1%) received intensive care and an additional 130,000 (17.3%) were ventilated in an intermediate care unit or cared for in a coronary care unit. Incidence increased >100-fold with age (0.2/1,000 in children to 26.2/1,000 in those >85 yrs old). Mortality was 28.6%, or 215,000 deaths nationally, and also increased with age, from 10% in children to 38.4% in those >85 yrs old. Women had lower age-specific incidence and mortality, but the difference in mortality was explained by differences in underlying disease and the site of infection. The average costs per case were $22,100, with annual total costs of $16.7 billion nationally. Costs were higher in infants, nonsurvivors, intensive care unit patients, surgical patients, and patients with more organ failure. The incidence was projected to increase by 1.5% per annum.
Conclusions: Severe sepsis is a common, expensive, and frequently fatal condition, with as many deaths annually as those from acute myocardial infarction. It is especially common in the elderly and is likely to increase substantially as the U.S. population ages.
Proinflammatory cytokines such as tumor necrosis factor- (TNF-) are critically involved in activation of the coagulation system in sepsis, leading to disseminated intravascular coagulation (DIC). Natural anticoagulants such as antithrombin (AT) and activated protein C (APC) regulate the coagulation system by inhibiting thrombin generation. In addition to these anticoagulant effects, both AT and APC have been shown to attenuate inflammatory responses induced by various noxious stimuli in rats such as lipopolysaccharide (LPS) challenge. AT promotes the endothelial release of prostacyclin, a potent anti-inflammatory prostaglandin that inhibits the monocytic production of TNF-, by interacting with cell-surface heparin-like substances. APC directly inhibits the production of TNF- by inhibiting the activation of both nuclear factor κB (NFκB) and activator protein-1 in monocytes stimulated with LPS. Thrombomodulin, an endothelial membranous integral protein that binds thrombin, exerts anti-inflammatory effects by generating APC. Furthermore, tissue factor pathway inhibitor, a natural anticoagulant for the extrinsic pathway of the coagulation system, also attenuates LPS-induced inflammatory responses in rats by inhibiting TNF- production by monocytes. These findings strongly suggest that natural anticoagulants could regulate inflammatory responses as well as the coagulation system in rats by inhibiting the monocytic production of TNF-. Such anti-inflammatory properties of natural anticoagulants are potentially important for their replacement in patients with sepsis who frequently develop DIC and organ failure as inflammatory responses.
Lipopolysaccharides (LPS, endotoxin) represent a major virulence factor of Gram-negative bacteria, which can cause septic shock in mammals, including man. The lipid anchor of LPS to the bacterial outer membrane, lipid A, exhibits a peculiar chemical structure, harbours the ‘endotoxic principle’ of LPS and is also responsible for the expression of pathophysiological effects. Chemically modified lipid A can be endotoxically inactive, but may express strong antagonistic activity against endotoxically active LPS. By applying orientation measurements with attenuated total reflectance (ATR) infrared spectroscopy on hydrated lipid A samples, we show here that these different biological activities are directly correlated to the intrinsic conformation of lipid A. Bisphosphoryl-hexaacyl lipid A molecules with an asymmetric (4/2) distribution of the acyl chains linked to the diglucosamine backbone have a large tilt angle (> 45 °) of the diglucosamine backbone with respect to the membrane surface, a conical molecular shape (larger cross-section of the hydrophobic than the hydrophilic moiety), and are endotoxically highly active. Monophosphoryl hexaacyl lipid A has a smaller tilt angle, and the conical shape is less expressed in favour of a more cylindrical shape. This correlates with decreasing endotoxic activity. Penta- and tetraacyl lipid A or hexaacyl lipid A with a symmetric acyl chain distribution (3/3) have a small tilt angle (< 25 °) and a cylindrical shape and are endotoxically inactive, but may be antagonistic.
Sepsis can be associated with profound alterations in the hemostatic mechanism. In this article we discuss recent insights into which mediators are involved in the activation of the coagulation system. We focus on studies performed in healthy humans intravenously injected with a low dose of endotoxin, and investigations in nonhuman primates infused with either endotoxin or live gram-negative bacteria. Special emphasis is given to the role of cytokines, in particular tumor necrosis factor-, interleukin (IL)-1, IL-6, IL-10 and IL-12. Moreover, the roles of tissue factor, activated protein C, and the fibrinolytic system are briefly addressed. Disseminated intravascular coagulation likely is the result of complex interactions between several host mediator systems.
Fever, hypotension and bleeding disorders are common symptoms of sepsis and septic shock. The activation of the contact-phase system is thought to contribute to the development of these severe disease states by triggering proinflammatory and procoagulatory cascades; however, the underlying molecular mechanisms are obscure. Here we report that the components of the contact-phase system are assembled on the surface of Escherichia coli and Salmonella through their specific interactions with fibrous bacterial surface proteins, curli and fimbriae. As a consequence, the proinflammatory pathway is activated through the release of bradykinin, a potent inducer of fever, pain and hypotension. Absorption of contact-phase proteins and fibrinogen by bacterial surface proteins depletes relevant coagulation factors and causes a hypocoagulatory state. Thus, the complex interplay of microbe surface proteins and host contact-phase factors may contribute to the symptoms of sepsis and septic shock.
Neutralization of proinflammatory cytokines, such as tumor necrosis factor-α (TNF-α) or interleukin-1 (IL-1), decreases mortality in several animal models of sepsis. However, recent clinical trials did not show an unequivocal improvement in survival. In contrast to animals, which succumb to shock during the first 72 hours, we found that many patients die much later with signs of opportunistic. Infections accompanied by downregulation of their monocytic HLA-DR expression and reduced ability to produce lipopolysaccharide (LPS)-induced TNF-α in vitro. This phenomenon of monocyte deactivation in septic patients with fatal outcome shows similarities to experimental monocytic refractoriness induced by LPS desensitization or by pretreatment with its endogenous mediators IL-10 and transforming growth factor-β (TGF-13)4. In order to strengthen their antimicrobial defense, here we tested whether interferon-γ (IFN-γ) can improve monocytic functions in these patients and in experimental monocytic deactivation. The considerably lowered in vitro levels of LPS-induced TNF-α in these situations were significantly enhanced by IFN-γ, but did not reach the extremely high levels of IFN-γ primed naive cells from healthy donors. Moreover, IFN-γ applied to septic patients with low monocytic HLA-DR expression restored the deficient HLA-DR expression and in vitro LPSinduced TNF-α secretion. Recovery of monocyte function resulted in clearance of sepsis in eight of nine patients. These data suggest that IFN-γ treatment in carefully selected septic patients is a novel therapeutic strategy worth pursuing.
The Toll-like receptor (TLR) family consists of phylogenetically conserved transmembrane proteins, which function as mediators of innate immunity for recognition of pathogen-derived ligands and subsequent cell activation via the Toll/IL-1R signal pathway. Here, we show that human TLR9 (hTLR9) expression in human immune cells correlates with responsiveness to bacterial deoxycytidylate-phosphate-deoxyguanylate (CpG)-DNA. Notably “gain of function” to immunostimulatory CpG-DNA is achieved by expressing TLR9 in human nonresponder cells. Transfection of either human or murine TLR9 conferred responsiveness in a CD14- and MD2-independent manner, yet required species-specific CpG-DNA motifs for initiation of the Toll/IL-1R signal pathway via MyD88. The optimal CpG motif for hTLR9 was GTCGTT, whereas the optimal murine sequence was GACGTT. Overall, these data suggest that hTLR9 conveys CpG-DNA responsiveness to human cells by directly engaging immunostimulating CpG-DNA.
Leukocytes respond to lipopolysaccharide (LPS) at nanogram per milliliter concentrations with secretion of cytokines such as tumor necrosis factor-alpha (TNF-alpha). Excess secretion of TNF-alpha causes endotoxic shock, an often fatal complication of infection. LPS in the bloodstream rapidly binds to the serum protein, lipopolysaccharide binding protein (LBP), and cellular responses to physiological levels of LPS are dependent on LBP. CD14, a differentiation antigen of monocytes, was found to bind complexes of LPS and LBP, and blockade of CD14 with monoclonal antibodies prevented synthesis of TNF-alpha by whole blood incubated with LPS. Thus, LPS may induce responses by interacting with a soluble binding protein in serum that then binds the cell surface protein CD14.
The soluble glycoprotein sCD14 binds lipopolysaccharide, a complex that activates endothelial cells and that may be crucial
in gram-negative sepsis, Therefore, serum sCD14 was analyzed in 54 patients with gram-negative septic shock and in 26 healthy
controls, sCD14 was tested by ELISA and Western blotting, Patients had higher sCD14 concentrations than controls (median,
3.23 vs. 2.48 µg/mL, P = .002). Increased levels were associated with high mortality (median, 4.2 µg/mL in nonsurvivors vs. 2.8 µg/mL in survivors, P = .001). sCD14 was found in two isoforms (49 and 55 kDa) in monocyte cultures. In sera only one of either form was detectable.
Controls had the 49-kDa form, and patients had either the 49- or 55-kDa form, but patients with high levels of sCD14 had only
the 55-kDa form. Twenty-one (53%) of 39 with the 55-kDa form and 8 (57%) of 14 with the 49-kDa form died. Thus, the level
of sCD14 but not its biochemical form had a prognostic value in patients with gram-negative septic shock.
Septic shock caused by a diverse group of bacterial pathogens is a serious human disease. Recognition of bacterial envelope constituents is one mechanism used by mammalian cells to initiate responses leading to bacterial killing or, unfortunately, responses that also cause fatal septic shock. Here we show that CD14 plays a key role in initiating cell activation by a group of bacterial envelope components from Gram-negative and Gram-positive microorganisms, as well as mycobacteria. We propose that CD14 is a receptor used by mammalian cells to recognize and signal responses to a diverse array of bacterial constituents. This finding defines the molecular basis for innate microbial immunity; implicit in these findings are new possibilities for therapeutics.
The spontaneous variability of arterial blood gas and pH values (ABGs) was examined in a group of 28 typical stable medical ICU patients under a variety of ventilatory conditions. In each patient, 13 ABG specimens were measured at 5-min intervals during a 1-h study period using a new bedside, extravascular fluorescent blood gas monitor. For all patients, the mean coefficient of variation (C) was 6.1 percent for PO2 and 4.7 percent for PCO2. The average SD for pH was 0.012. We conclude that the spontaneous variability for ABG values over a 1-h period is substantial and that this variability should be taken into account when making clinical decisions based on ABG values.
Neutralization of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha) or interleukin-1 (IL-1), decreases mortality in several animal models of sepsis. However, recent clinical trials did not show an unequivocal improvement in survival. In contrast to animals, which succumb to shock during the first 72 hours, we found that many patients die much later with signs of opportunistic infections accompanied by downregulation of their monocytic HLA-DR expression and reduced ability to produce lipopolysaccharide (LPS)-induced TNF-alpha in vitro. This phenomenon of monocyte deactivation in septic patients with fatal outcome shows similarities to experimental monocytic refractoriness induced by LPS desensitization or by pretreatment with its endogenous mediators IL-10 and transforming growth factor-beta (TGF-beta). In order to strengthen their antimicrobial defense, here we tested whether interferon-gamma (IFN-gamma) can improve monocytic functions in these patients and in experimental monocytic deactivation. The considerably lowered in vitro levels of LPS-induced TNF-alpha in these situations were significantly enhanced by IFN-gamma, but did not reach the extremely high levels of IFN-gamma primed naive cells from healthy donors. Moreover, IFN-gamma applied to septic patients with low monocytic HLA-DR expression restored the deficient HLA-DR expression and in vitro LPS-induced TNF-alpha secretion. Recovery of monocyte function resulted in clearance of sepsis in eight of nine patients. These data suggest that IFN-gamma treatment in carefully selected septic patients is a novel therapeutic strategy worth pursuing.
Induction of the adaptive immune response depends on the expression of co-stimulatory molecules and cytokines by antigen-presenting cells. The mechanisms that control the initial induction of these signals upon infection are poorly understood. It has been proposed that their expression is controlled by the non-clonal, or innate, component of immunity that preceded in evolution the development of an adaptive immune system in vertebrates. We report here the cloning and characterization of a human homologue of the Drosophila toll protein (Toll) which has been shown to induce the innate immune response in adult Drosophila. Like Drosophila Toll, human Toll is a type I transmembrane protein with an extracellular domain consisting of a leucine-rich repeat (LRR) domain, and a cytoplasmic domain homologous to the cytoplasmic domain of the human interleukin (IL)-1 receptor. Both Drosophila Toll and the IL-1 receptor are known to signal through the NF-kappaB pathway. We show that a constitutively active mutant of human Toll transfected into human cell lines can induce the activation of NF-kappaB and the expression of NF-kappaB-controlled genes for the inflammatory cytokines IL-1, IL-6 and IL-8, as well as the expression of the co-stimulatory molecule B7.1, which is required for the activation of naive T cells.
Discovered in the early 1960s as a T cell cytokine, the protein mediator known as macrophage migration inhibitory factor (MIF) has been found recently to be a pituitary peptide released during the physiological stress response, a proinflammatory macrophage cytokine secreted after LPS stimulation, and a T cell product expressed as part of the antigen-dependent activation response. We report herein that MIF also plays a critical role in the innate host response to staphylococcal and streptococcal exotoxins. In RAW 264.7 or elicited mouse peritoneal macrophages, peak MIF secretion was induced by concentrations of the staphylococcal toxic shock syndrome (TSS) toxin 1 (TSST-1) and the streptococcal pyrogenic exotoxin A as low as 10 pg/ml. Moreover, dose-response studies of splenocyte cytokine production showed that lower concentrations of TSST-1 (10 pg/ml) were needed to release MIF than to induce interleukin 2 or interferon-gamma secretion (1 ng/ml). We also studied the effect of neutralizing anti-MIF antibodies on TSST-1-induced lymphocyte proliferation and lethal toxic shock. Pretreatment of C57BL/6 mice with anti-MIF antibody 2 hr before TSST-1 injection prevented spleen enlargement and reduced by 50% the proliferation of splenocytes measured ex vivo. In a lethal mouse model of TSST-1-induced shock, anti-MIF antibody increased survival from 8% to 54% (P < 0.0001). These studies indicate that Gram-positive exotoxins are extremely potent inducers of MIF secretion and establish a critical role for MIF and the macrophage in the pathogenesis of the TSSs and in the innate immune response.
In the face of the unique diversity and plasticity of the immune system pathogenic organisms have developed multiple mechanisms in adaptation to their hosts, including the expression of a particular class of molecules called superantigens. Bacterial superantigens are the most potent stimulators of T cells. The functional consequences of the expression of superantigens by bacteria can be extended not only to T lymphocytes, but also to B lymphocytes and to cells of the myeloid compartment, including antigen-presenting cells and phagocytes. The biological effects of bacterial superantigens as well as their molecular aspects have now been studied for a decade. Although there is still a long way to go to clearly understand the role these molecules play in the establishment of disease, recently acquired knowledge of their biochemistry now offers unique experimental opportunities in defining the molecular rules of T-cell activation. Here, we present some of the most recent functional and molecular aspects of the interaction of bacterial superantigens with MHC class II molecules and the T-cell receptor.
The purpose of this study was to determine whether apoptosis is a major mechanism of cell death in patients with sepsis. The activities of caspase-3 and the antiapoptotic protein, BCL-2, were investigated also.
A prospective study of 20 patients who died of sepsis and multiple organ dysfunction was performed. The control group of 16 patients consisted of critically ill, nonseptic patients who were evaluated either prospectively (7) or retrospectively (9). In addition, normal colon sections from seven patients who had bowel resections were included. Apoptosis was evaluated in hematoxylin and eosin-stained specimens by deoxyuridine triphosphate nick end-labeling (TUNEL) and by DNA gel electrophoresis.
Two academic medical centers.
Critically ill patients.
In septic patients, apoptosis was detected in diverse organs by all three methods with a predominance in lymphocytes and intestinal epithelial cells. Hematoxylin and eosin-stained specimens from septic patients demonstrated at least focal apoptosis in 56.3% of spleens, 47.1% of colons, and 27.7% of ileums. Indirect evidence of lymphocyte apoptosis in septic patients included extensive depletion of lymphocytes in white pulp and a marked lymphocytopenia in 15 of 19 patients. Hematoxylin and eosin from nonseptic patients' tissues revealed a low level of apoptosis in one patient only. The TUNEL method increased in positivity with a delay in tissue fixation and was highly positive in many tissues from both septic and nonseptic patients. Immunohistochemical staining for active caspase-3 showed a marked increase in septic vs. nonseptic patients (p < .01), with >25% to 50% of cells being positive focally in the splenic white pulp of six septic but in no nonseptic patients.
We conclude that caspase-3-mediated apoptosis causes extensive lymphocyte apoptosis in sepsis and may contribute to the impaired immune response that characterizes the disorder.
Disseminated intravascular coagulation is characterized by the widespread activation of coagulation, which results in the intravascular formation of fibrin and ultimately thrombotic occlusion of small and midsize vessels.1–3 Intravascular coagulation can also compromise the blood supply to organs and, in conjunction with hemodynamic and metabolic derangements, may contribute to the failure of multiple organs. At the same time, the use and subsequent depletion of platelets and coagulation proteins resulting from the ongoing coagulation may induce severe bleeding (Figure 1). Bleeding may be the presenting symptom in a patient with disseminated intravascular coagulation, a factor that can complicate decisions about . . .
Toll-like receptor (TLR) 2 and TLR4 are implicated in the recognition of various bacterial cell wall components, such as lipopolysaccharide (LPS). To investigate in vivo roles of TLR2, we generated TLR2-deficient mice. In contrast to LPS unresponsiveness in TLR4-deficient mice, TLR2-deficient mice responded to LPS to the same extent as wild-type mice. TLR2-deficient macrophages were hyporesponsive to several Gram-positive bacterial cell walls as well as Staphylococcus aureus peptidoglycan. TLR4-deficient macrophages lacked the response to Gram-positive lipoteichoic acids. These results demonstrate that TLR2 and TLR4 recognize different bacterial cell wall components in vivo and TLR2 plays a major role in Gram-positive bacterial recognition.
Identification of new therapeutic targets for the management of septic shock remains imperative as all investigational therapies, including anti-tumor necrosis factor (TNF) and anti-interleukin (IL)-1 agents, have uniformly failed to lower the mortality of critically ill patients with severe sepsis. We report here that macrophage migration inhibitory factor (MIF) is a critical mediator of septic shock. High concentrations of MIF were detected in the peritoneal exudate fluid and in the systemic circulation of mice with bacterial peritonitis. Experiments performed in TNFalpha knockout mice allowed a direct evaluation of the part played by MIF in sepsis in the absence of this pivotal cytokine of inflammation. Anti-MIF antibody protected TNFalpha knockout from lethal peritonitis induced by cecal ligation and puncture (CLP), providing evidence of an intrinsic contribution of MIF to the pathogenesis of sepsis. Anti-MIF antibody also protected normal mice from lethal peritonitis induced by both CLP and Escherichia coli, even when treatment was started up to 8 hours after CLP. Conversely, co-injection of recombinant MIF and E. coli markedly increased the lethality of peritonitis. Finally, high concentrations of MIF were detected in the plasma of patients with severe sepsis or septic shock. These studies define a critical part for MIF in the pathogenesis of septic shock and identify a new target for therapeutic intervention.
Despite intensive efforts, the development of novel drugs for the treatment of sepsis has proved to be extremely difficult.
A large number of clinical trials have ended in failure. A critical analysis of this record suggests that there is no single
reason for these problems. Rather, the explanation lies in part with unexpected failures in the drugs themselves, and in part
with the difficulties of trial design in this particular group of patients. In future, trials in this area are likely to be
more highly focused, with even stricter protocol definitions to try and ensure a homogeneous patient population.
Superantigens are highly potent immune stimulators with a unique ability to interact simultaneously with MHC class II molecules and T cell receptors, forming a trimolecular complex that induces profound T-cell proliferation and massive cytokine production. Recent structural studies have provided a wealth of information regarding these complex interactions, and it is now emerging that, despite their common 3-D architecture, superantigens are able to crosslink MHC class II molecules and T cell receptors in a variety of ways.