[Show abstract][Hide abstract]ABSTRACT: An improved number of anti-fungal drugs are currently available for the treatment of invasive aspergillosis (IA). While serial galactomannan index (GMI) measurement can be used to monitor response to treatment, the extent to which different anti-fungal regimens can affect galactomannan levels is unknown. In 147 IA patients receiving either voriconazole (VCZ) or conventional amphotericin B (CAB) in a multicentre clinical trial, we performed post-hoc analyses of GMI trends in relation to outcomes. The generalized estimation equations approach was used to estimate changes in the effect size for GMI over time within patients. Patients who received VCZ primary therapy and had good treatment response 12 weeks later showed earlier decreases in GMI values at Week 1 and Week 2 (p = 0.001 and 0.046 respectively) as compared to patients who only received CAB. At end-of-randomized therapy (EORT), which was a pre-set secondary assessment point for all patients who switched from randomized primary (CAB or VCZ) to an alternative anti-fungal drug, treatment failure was associated with increasing GMI at Weeks 1 and 2 in CAB-primary treated patients (p = 0.022 and 0.046 respectively). These distinct trends highlight the variations in GMI kinetics with the use of different anti-fungal drugs and their implications in relation to IA treatment response.
[Show abstract][Hide abstract]ABSTRACT: Aspergillus fumigatus is a fungus that causes opportunistic infections in immunocompromised patients, with high morbidity and mortality. In its turn, A. fumigatus can become infected with mycoviruses. Most mycoviruses have a dsRNA genome and can cause fungal hypovirulence. For that reason, mycoviruses could theoretically be used as therapeutic tools to combat fungal infections. We determined if a certain genetic make-up of A. fumigatus was associated with the presence of mycoviruses in 86 clinical A. fumigatus isolates. Mycovirus screening was performed by isolating dsRNA from mycelial cultures using a Trizol/Chloroform method. The genetic relatedness of dsRNA infected A. fumigatus was determined by cell surface protein (CSP) typing and determination of the mating type. Sixteen (18.6%) of the 86 clinical A. fumigatus isolates contained dsRNA. The A. fumigatus collection could be divided into 11 different CSP types. DsRNA infected A. fumigatus isolates had similar CSP types as non-infected isolates. In both cases, the CSP types t01, t02, t03 and t04 were the most prevalent and the distribution comparable to the CSP types observed in other Dutch collections. Mating types MAT1-1 and MAT1-2 were evenly distributed among all A. fumigatus strains, regardless of CSP type. No difference was observed in mycovirus infections between MAT1-1 and MAT1-2 isolates. DsRNA mycovirus infections in A. fumigatus are not related to either CSP or mating type and therefore represent an interesting future therapeutic tool to combat fungal infections.
[Show abstract][Hide abstract]ABSTRACT: Author Summary
Eumycetoma is a mutilating fungal disease of mainly the foot and is found in (sub)tropical regions such as Sudan. At the moment it is not understood why some people develop eumycetoma and others not. In the regions were eumycetoma is prevalent many other infections are also found. These infections could alter the immune system which makes people more or less susceptible in obtaining another infection. One of the infections with such an effect is Schistosomiasis. In Africa, eumycetoma is found in regions were schistosomiasis is prevalent. In this study we show that eumycetoma patients more often have antibodies against Schistosoma species, than healthy controls from the same region. In contrast, eumycetoma patients did not have more often antibodies against Toxoplasma species. This might implicate that schistosomiasis predisposes eumycetoma development. If schistosomiasis indeed predisposes eumycetoma development, eradicating Schistosoma in a population could also lower the number of eumycetoma cases in that area, which in the end could lead to intervention strategies not only for schistosomiasis but also for eumycetoma.
[Show abstract][Hide abstract]ABSTRACT: Objectives:
The underlying mechanism for amphotericin B-induced acute kidney injury (AKI) remains poorly understood and may be immunologically mediated. We assessed whether the development of nephrotoxicity is linked to a distinct cytokine profile in patients receiving amphotericin B deoxycholate (AmBD).
Patients and methods:
In 58 patients who received AmBD, circulating serum interleukin (IL)-6, IL-8 and IL-10 were measured at baseline, week 1 and week 2 of antifungal treatment and correlated to the development of renal impairment. The Cox proportional hazards model approach was adopted for analysis.
The P value was 0.026 for the overall effect of IL-6 on time to development of AKI. An increasing or non-receding IL-6 trend by week 1 of AmBD treatment (followed by a decreasing or non-receding IL-6 trend from week 1 to week 2) correlated with an increased likelihood of nephrotoxicity [hazard ratio (HR) 6.93, P value 0.005 and HR 3.46, P value 0.035, respectively]. Similarly, persistently increasing IL-8 levels were linked to a 3.84-fold increased likelihood of AKI.
In patients receiving AmBD, persistence of an elevated pro-inflammatory cytokine milieu is associated with a predisposition to drug-related kidney injury.
[Show abstract][Hide abstract]ABSTRACT: Noroviruses (NoVs) have emerged as the leading cause of acute viral gastroenteritis (GE) in humans. Although diagnostic facilities have greatly improved, significant underdiagnosis of NoV in hospitals may still occur, thereby increasing clinical burden and nosocomial spread. We evaluated the underdiagnosis of sporadic NoV infections in a tertiary care hospital and estimated its clinical impact. From December 2008 until July 2009, fecal samples specifically referred for bacterial but not viral examination were retrospectively tested for NoV by real-time PCR. The clinical and virological data from patients with undiagnosed NoV infection (missed patients) were evaluated and compared with those from patients with recognized NoV. During the study period, 45 patients with undiagnosed NoV were detected, whereas 50 patients were regularly diagnosed. The missed NoV cases were more frequently adults than children (80% versus 46%; P < 0.001). The viral load levels did not differ between the diagnosed and missed patients, but missed patients more frequently presented without diarrhea (20% versus 4%; P < 0.07). The newly admitted missed NoV cases with GE underwent more diagnostic imaging (24% versus 4%; P < 0.01) and tended to be hospitalized longer. When missed-NoV patients were included, the number of nosocomial clusters doubled and missed patients were index cases in 5 of the 6 clusters. These data indicate that NoV infections are frequently missed despite routine laboratory testing and demonstrate that underdiagnosis of NoV patients is associated with costly abdominal imaging and nosocomial clustering. Awareness of NoV infection in adult patients and education about the importance of viral GE should be increased.
[Show abstract][Hide abstract]ABSTRACT: The monitoring and prediction of treatment responses to invasive aspergillosis (IA) are difficult. We determined whether serum galactomannan index (GMI) trends early in the course of disease may be useful in predicting eventual clinical outcomes. For the subjects recruited into the multicenter Global Aspergillosis Study, serial GMIs were measured at baseline and at weeks 1, 2, and 4 following antifungal treatment. Clinical response and survival at 12 weeks were the outcome measures. GMI trends were analyzed by using the generalized estimation equation approach. GMI cutoffs were evaluated by using receiver-operating curve analyses incorporating pre- and posttest probabilities. Of the 202 study patients diagnosed with IA, 71 (35.1%) had a baseline GMI of ≥ 0.5. Week 1 GMI was significantly lower for the eventual responders to treatment at week 12 than for the nonresponders (GMIs of 0.62 ± 0.12 and 1.15 ± 0.22, respectively; P = 0.035). A GMI reduction of >35% between baseline and week 1 predicted a probability of a satisfactory clinical response. For IA patients with pretreatment GMIs of <0.5 (n = 131; 64.9%), GMI ought to remain low during treatment, and a rising absolute GMI to >0.5 at week 2 despite antifungal treatment heralded a poor clinical outcome. Here, every 0.1-unit increase in the GMI between baseline and week 2 increased the likelihood of an unsatisfactory clinical response by 21.6% (P = 0.018). In summary, clinical outcomes may be anticipated by charting early GMI trends during the first 2 weeks of antifungal therapy. These findings have significant implications for the management of IA.
Preview · Article · May 2012 · Journal of clinical microbiology
[Show abstract][Hide abstract]ABSTRACT: Polymorphonuclear neutrophils (PMNs) are important phagocytes in the control of Candida infections. The phagocytic contribution of PMNs to host defence can by assessed by various methods, such as microbiological assays. However, assessment and definition of intracellular killing capacity can be a source of considerable confusion. A comparison of the growth of Candida in the presence of PMN with the growth of Candida in phagocyte-free suspensions may lead to an overestimation of killing capacity because PMNs can use both intracellular and extracellular killing mechanisms. Here, we describe the use of an adherent monolayer of exudate peritoneal PMNs that is used to differentiate between the process of phagocytosis and intracellular killing.
No preview · Article · Jan 2012 · Methods in molecular biology (Clifton, N.J.)
[Show abstract][Hide abstract]ABSTRACT: Dectin-1 is the major receptor for fungal β-glucans on myeloid cells. We investigated whether defective Dectin-1 receptor function, because of the early stop codon polymorphism Y238X, enhances susceptibility to invasive aspergillosis (IA) in at-risk patients.
Association of Dectin-1 Y238X polymorphism with occurrence and clinical course of IA was evaluated in 71 patients who developed IA post hematopoietic stem cell transplantation (HSCT) and in another 21 non-HSCT patients with IA. The control group consisted of 108 patients who underwent HSCT. Functional studies were performed to investigate consequences of the Y238X Dectin-1 polymorphism.
The Y238X allele frequency was higher in non-HSCT patients with IA (19.0% vs 6.9%-7.7%; P < .05). Heterozygosity for Y238X polymorphism in HSCT recipients showed a trend toward IA susceptibility (odds ratio, 1.79; 95% CI, .77-4.19; P = .17) but did not influence clinical course of IA. Functional assays revealed that although peripheral blood mononuclear cells with defective Dectin-1 function due to Y238X responded less efficiently to Aspergillus, corresponding macrophages showed adequate response to Aspergillus.
Dectin-1 Y238X heterozygosity has a limited influence on susceptibility to IA and may be important in susceptible non-HSCT patients. This is partly attributable to redundancy inherent in the innate immune system. Larger studies are needed to confirm these findings.
Full-text · Article · Mar 2011 · The Journal of Infectious Diseases
[Show abstract][Hide abstract]ABSTRACT: The relevance of studies aimed at understanding host immune response against Aspergillus fumigatus takes on much significance given that all patients with invasive aspergillosis are invariably immunocompromised. This article attempts to correlate relevant findings from recent experimental studies to clinical observations made by the physician at the bedside. It is hoped that the increased understanding of host-fungus immune interaction may pave the way for the development of new management strategies against this difficult-to-treat fungal disease.
No preview · Article · Jan 2011 · Future Microbiology
[Show abstract][Hide abstract]ABSTRACT: Joosten LAB, van de Veerdonk F, Vonk AG, Boerman OC, Keuter M, Fantuzzi G, Verschueren I, van der Poll T, Dinarello CA, Kullberg BJ, Van der Meer JWM, Netea MG. Differential susceptibility to lethal endotoxaemia in mice deficient in IL-1α, IL-1β or IL-1 receptor type I. APMIS 2010; 118: 1000–7.
The role of intereukin-1 (IL-1) in mortality caused by endotoxaemia remains controversial. While IL-1 receptor antagonist (IL-1Ra) protects mice from lethal endotoxaemia, mice deficient in IL-1β (IL-1β− /−) display normal susceptibility to lipopolysaccharide (LPS). The aim of this study was to identify the source of these discrepancies. Mice deficient in IL-1α, IL-1β or IL-1R type I were injected intraperitoneally with Escherichia coli or Salmonella typhimurium LPS. Survival of the mice was examined and compared with C57/Bl6 wild-type mice. In addition, serum cytokine concentrations were determined after LPS challenge and in vitro cytokine production by peritoneal macrophages was analysed. Clearance of radioactive IL-1α was examined in IL-1α−/− and wild-type mice. IL-1β−/− mice were normally susceptible to endotoxaemia and cytokine production did not differ from that in control mice. Surprisingly, LPS mortality in IL-1α−/− mice was significantly greater than that in control mice, accompanied by higher interferon-γ release. These effects were mediated by a distorted homeostasis of IL-1RI receptors, as shown by a strongly delayed clearance of IL-1α. In contrast to the IL-1α−/− and IL-1β−/− mice, IL-1RI−/− mice were completely resistant to high doses of LPS. In conclusion, IL-1RI-mediated signals are crucial in mediating mortality occurring as a result of lethal endotoxaemia. Investigation of IL-1-mediated pathways in IL-1 knock-out mice is complicated by a distorted homeostasis of IL-1Rs.
[Show abstract][Hide abstract]ABSTRACT: Aspergillus fumigatus conidia attenuates host proinflammatory responses through modulation of Toll-like receptor (TLR)2 and TLR4 signaling, but the precise mechanisms that mediate this effect are not known. In the present study, the role of the Aspergillus cell wall polysaccharide constituents responsible for the modulation of host capability to mount a proinflammatory response was studied. Aspergillus cell wall fractions and its major components showed differential capabilities in modulating host TLR-mediated interleukin (IL)-6 production. Beta-glucan specifically suppressed TLR4-induced response, while alpha-glucan inhibited IL-6 induced through TLR2- and TLR4-stimulation. Galactomannan diminished TLR4-mediated response, while its inhibitory effects on TLR2-signaling were limited. Chitin, on the other hand, did not have significant immunomodulatory capability. The ability of the fungal cell wall to alter the immune signature of the pathogen may contribute to its virulence and the pathogenesis of co-infection.
Full-text · Article · Oct 2010 · Microbes and Infection
[Show abstract][Hide abstract]ABSTRACT: Monitoring treatment response in invasive aspergillosis is challenging, because an immunocompromised host may not exhibit reliable symptoms and clinical signs. Cytokines play a pivotal role in mediating host immune response to infection; therefore, the profiling of biomarkers may be an appropriate surrogate for disease status.
We studied, in a cohort of 119 patients with invasive aspergillosis who were recruited in a multicenter clinical trial, serum interleukin (IL)-6, IL‐8, IL‐10, interferon‐γ, and C‐reactive protein (CRP) trends over the first 4 weeks of therapy and correlated these trends to clinical outcome parameters.
Circulating IL‐6 and CRP levels were high at initiation of therapy and generally showed a downward trend with antifungal treatment. However, subjects with adverse outcomes exhibited a distinct lack of decline in IL‐6 and CRP levels at week 1, compared with responders (P = .02, for both IL‐6 and CRP). Nonresponders also had significantly elevated IL‐8 levels (P = .001).
High initial IL‐8 and persistently elevated IL‐6, IL‐8, and CRP levels after initiation of treatment may be early predictors of adverse outcome in invasive aspergillosis. Cytokine and CRP profiles could be used for early identification of patients with a poor response to antifungal treatment who may benefit from more‐aggressive antimicrobial regimens.
Full-text · Article · Sep 2010 · The Journal of Infectious Diseases
[Show abstract][Hide abstract]ABSTRACT: Invasive fungal infections are relatively common opportunistic infections in immunocompromised patients and are still associated with a high mortality rate. Furthermore, these infections are often complicated by resistance or refractoriness to current antimicrobial agents. Therefore, an urgent need exists for new therapeutic strategies based on the identification of new microbial targets and novel antimicrobial agents. One such hypothetical therapeutic strategy may involve the use of mycoviruses that are able to selectively infect fungi. Current knowledge of mycoviruses of human pathogenic fungi and the scope for using (recombinant) mycoviruses as future biological control agents are reviewed here.
Full-text · Article · Jul 2010 · European Journal of Clinical Microbiology
[Show abstract][Hide abstract]ABSTRACT: The role of intereukin-1 (IL-1) in mortality caused by endotoxaemia remains controversial. While IL-1 receptor antagonist (IL-1Ra) protects mice from lethal endotoxaemia, mice deficient in IL-1beta (IL-1beta( /)) display normal susceptibility to lipopolysaccharide (LPS). The aim of this study was to identify the source of these discrepancies. Mice deficient in IL-1alpha, IL-1beta or IL-1R type I were injected intraperitoneally with Escherichia coli or Salmonella typhimurium LPS. Survival of the mice was examined and compared with C57/Bl6 wild-type mice. In addition, serum cytokine concentrations were determined after LPS challenge and in vitro cytokine production by peritoneal macrophages was analysed. Clearance of radioactive IL-1alpha was examined in IL-1alpha(/) and wild-type mice. IL-1beta(/) mice were normally susceptible to endotoxaemia and cytokine production did not differ from that in control mice. Surprisingly, LPS mortality in IL-1alpha(/) mice was significantly greater than that in control mice, accompanied by higher interferon-gamma release. These effects were mediated by a distorted homeostasis of IL-1RI receptors, as shown by a strongly delayed clearance of IL-1alpha. In contrast to the IL-1alpha(/) and IL-1beta(/) mice, IL-1RI(/) mice were completely resistant to high doses of LPS. In conclusion, IL-1RI-mediated signals are crucial in mediating mortality occurring as a result of lethal endotoxaemia. Investigation of IL-1-mediated pathways in IL-1 knock-out mice is complicated by a distorted homeostasis of IL-1Rs.
[Show abstract][Hide abstract]ABSTRACT: Both interferon-gamma-producing type 1 T helper (Th1)- and interleukin-17 (IL-17)-producing Th17 cells have been proposed to be involved in anti-fungal host defence. Although invasive aspergillosis is one of the most severe human fungal infections, little is known regarding the relative importance of the Th1 versus Th17 cellular immune pathways for the human anti-Aspergillus host defence. Using human peripheral blood mononuclear cells and a system consisting of monocyte-derived macrophages with lymphocytes, we found that Aspergillus fumigatus is a weak inducer of human IL-17 but induces a strong Th1 response. These data were validated by the very low IL-17 levels in bronchoalveolar lavage fluid and serum of patients with invasive aspergillosis. Surprisingly, live A. fumigatus reduced IL-17 production induced by mitogenic stimuli. This effect was mediated through the propensity of A. fumigatus to metabolize tryptophan and release kynurenine, which modulates the inflammatory response through inhibition of IL-17 production. In conclusion, A. fumigatus does not stimulate production of IL-17 and human host defence against aspergillosis may not rely on potent Th17 responses.
[Show abstract][Hide abstract]ABSTRACT: Melanin biopigments have been linked to fungal virulence. Aspergillus fumigatus conidia are melanised and are weakly immunogenic. We show that melanin pigments on the surface of resting Aspergillus fumigatus conidia may serve to mask pathogen-associated molecular patterns (PAMPs)-induced cytokine response. The albino conidia induced significantly more proinflammatory cytokines in human peripheral blood mononuclear cells (PBMC), as compared to melanised wild-type conidia. Blocking dectin-1 receptor, Toll-like receptor 4 or mannose receptor decreased cytokine production induced by the albino but not by the wild type conidia. Moreover, albino conidia stimulated less potently, cytokine production in PBMC isolated from an individual with defective dectin-1, compared to the stimulation of cells isolated from healthy donors. These results suggest that β-glucans, but also other stimulatory PAMPs like mannan derivatives, are exposed on conidial surface in the absence of melanin. Melanin may play a modulatory role by impeding the capability of host immune cells to respond to specific ligands on A. fumigatus.
[Show abstract][Hide abstract]ABSTRACT: A successful pathogen is one that is able to effectively survive and evade detection by the host innate immune defense. Fungal pathogens have adopted strategies which evade host defense and eventually cause disease in at-risk patients. Shielding of stimulatory surface recognition molecules, shedding of decoy components, induction of anti-inflammatory signals, complement evasion and resilient survival capacity are successful evasion mechanisms employed by fungal pathogens. Understanding these complex pathways of immune evasion can potentially contribute to development of novel therapeutic strategies against fungal infections.
Full-text · Article · May 2009 · Medical mycology: official publication of the International Society for Human and Animal Mycology
[Show abstract][Hide abstract]ABSTRACT: Toll-like receptor (TLR)-based signaling pathways in the host may be modulated by pathogens during the course of infection.
We describe a novel immunomodulatory mechanism in which Aspergillus fumigatus conidia induce attenuation of TLR2- and TLR4-mediated interleukin (IL)-6 and IL-1β proinflammatory responses in human mononuclear
cells with suppression of IL-1β mRNA transcription. Background TLR2 and TLR4 mRNA transcription was not influenced. A. fumigatus conidia induced TLR2 internalization and uptake into the phagosome with a resultant decrease in surface receptor expression.
A. fumigatus hyphae, on the other hand, selectively downregulated the TLR4-mediated response. These novel immunosuppressive effects may
facilitate the invasiveness of A. fumigatus.
Full-text · Article · Mar 2009 · Infection and immunity