[Show abstract][Hide abstract] ABSTRACT: When mice are subjected to a Pseudomonas aeruginosa challenge 5 days after cecal ligation and puncture (CLP), clearance of the Pseudomonas is diminished when compared to sham mice. The object of this study was to determine which component(s) of CLP contributed to the impairment of the innate immune response. Mice subjected to either trauma alone or cecal ischemia/necrosis alone did not have impaired ability to clear a subsequent Pseudomonas challenge (determined by colony-forming units (cfu's) after culture of spleen tissue). However, mice subjected to abdominal contamination with heat-killed cecal contents had reduced ability to clear the subsequent Pseudomonas challenge. In contrast to normobiotic mice, neither CLP performed in germ-free mice nor abdominal contamination of mice with cecal contents from germ-free mice adversely affected clearance of a subsequent Pseudomonas challenge. These data suggest that suppressed immune function after CLP is due to exposure to microbial ligands within the cecal lumen rather than tissue trauma, ischemia, or necrosis. However, suppression of immune function did not appear to be due to exposure to LPS as TLR4-deficient mice subject to abdominal contamination with cecal contents had diminished clearance of a Pseudomonas challenge similar to that seen in wild-type mice.
Microbes and Infection 08/2011; 14(1):35-42. DOI:10.1016/j.micinf.2011.08.002 · 2.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mice that have been subjected to cecal ligation and puncture (CLP) have an impaired ability to clear a subsequent Pseudomonas aeruginosa challenge compared with that of sham CLP controls. We hypothesized that this outcome is dependent upon a caspase-1 mechanism and tested this hypothesis by measuring caspase-1 after CLP and by measuring clearance of a bacterial challenge in caspase-1-deficient mice after CLP. Wild-type mice subjected to CLP had increased caspase-1 activity as well as increased IL-1β and increased IL-18 production in splenocytes stimulated with heat-killed Pseudomonas and had increased plasma concentrations of IL-1β and IL-18 and impaired clearance of a P. aeruginosa challenge compared with sham controls. Healthy, uninjured caspase-1(-\-) mice did not differ from wild-type mice in their ability to clear a Pseudomonas challenge. However, unlike wild-type mice, caspase-1(-/-) mice subjected to CLP had no impairment of bacterial clearance of the Pseudomonas challenge, suggesting that caspase-1 induction after CLP played a role in impairment of bacterial clearance. This was further substantiated by the use of a specific caspase-1 inhibitor, Ac-YVAD-CMK. Wild-type mice treated with Ac-YVAD-CMK (10 mg/kg s.c. twice daily, initiated at time of CLP) did not have impaired clearance of a Pseudomonas challenge compared with that of sham mice and had significantly improved bacterial clearance compared with that of untreated CLP mice. Increased caspase-1 expression and activity after CLP injury appears to contribute to diminished innate immune function.
The Journal of Immunology 06/2011; 187(2):905-10. DOI:10.4049/jimmunol.1002102 · 5.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Several studies indicate that IFN-γ facilitates systemic inflammation during endotoxin-induced shock. However, the pathobiology of IFN-γ in clinically relevant models of septic shock, such as CLP, is not well understood. In this study, the role of IFN-γ in the pathogenesis of CLP-induced septic shock was evaluated by examining IFN-γ production at the tissue and cellular levels. The impact of IFN-γ neutralization on systemic inflammation, bacterial clearance, and survival was also determined. Following CLP, concentrations of IFN-γ in plasma and peritoneal lavage fluid were low in comparison with concentrations of IL-6 and MIP-2, as was IFN-γ mRNA expression in liver and spleen. The overall percentage of IFN-γ+ splenocytes was <5% after CLP and not statistically different from control mice. Intracellular IFN-γ was present in a large proportion of peritoneal exudate cells after CLP, primarily in infiltrating myeloid cells and NK cells. i.p. myeloid cell activation was decreased in IFN-γKO mice, and plasma concentrations of IL-6 and MIP-2 were significantly lower in IFN-γKO mice and in mice treated with anti-IFN-γ compared with controls, but bacterial clearance was not affected. IFN-γKO mice were resistant to CLP-induced mortality when treated with systemic antibiotics. However, neutralization of IFN-γ with blocking antibodies did not improve survival significantly. These studies show that IFN-γ facilitates the proinflammatory response during CLP-induced septic shock. However, neutralization of IFN-γ did not improve survival uniformly.
[Show abstract][Hide abstract] ABSTRACT: To determine whether tolerance and enhancement of innate immune function can be induced by the Gram-positive cell wall component peptidoglycan.
Controlled, in vivo laboratory study.
Male mice, 8-12 wks (C57BL6/J; C3H/HeJ; B6.129-Tlr2/J).
Mice were given intraperitoneal injections of 1 mg peptidoglycan on two consecutive days. Mice were then challenged with an intravenous injection of live Staphylococcus aureus (1 x 10 colony-forming units) 2 days after the second pretreatment.
Mice pretreated with peptidoglycan had diminished plasma concentrations of tumor necrosis factor-alpha and interferon-gamma in response to the bacterial challenge when compared with untreated controls. Plasma interleukin-10 after bacterial challenge was higher in peptidoglycan-pretreated mice than in controls. Clearance of bacteria after the staphylococcal challenge was improved in mice pretreated with peptidoglycan, and mortality in response to a subsequent Staphylococcus challenge was significantly attenuated. Peptidoglycan pretreatment of mice lacking intact toll-like receptor-4 signaling (C3H/HeJ) or toll-like receptor-2 signaling (toll-like receptor-2 knockouts) had similar effects on plasma cytokine balance, bacterial clearance, and mortality.
Exposure to peptidoglycan significantly attenuated inflammation and enhanced bacterial clearance after a subsequent challenge with S. aureus. These results show that exposure to Gram-positive bacterial cell wall components can induce tolerance and enhance innate immune function and neither toll-like receptor-2 nor toll-like receptor-4 are necessary for this phenomenon. Further, although the altered cytokine balance is similar to that seen in septic patients, induced tolerance differs importantly from the clinical scenario of sepsis in that bacterial clearance and survival are improved compared with normal control animals.
Critical care medicine 10/2008; 36(11):3067-73. DOI:10.1097/CCM.0b013e31818c6fb7 · 6.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The objective of this study was to determine if inflammatory tolerance and enhancement of innate immune function could be induced by the Gram-positive cell wall component peptidoglycan (PGN). Male mice (C57BL6/J or C3H/HeJ, 8-12 weeks of age) were given intraperitoneal injections of 1mg PGN on 2 consecutive days. The mice were then challenged with lipopolysaccharide (LPS) or live Pseudomonas aeruginosa (1 x 10(8) colony-forming units) 2 days after the second pretreatment. Mice pretreated with PGN had diminished plasma concentrations of TNFalpha and IFNgamma and elevated concentrations of IL-10 in response to a subsequent LPS or Pseudomonas challenge when compared to untreated controls. Bacterial clearance was improved in mice pretreated with PGN, and mortality in response to a subsequent Pseudomonas challenge was significantly attenuated. PGN pretreatment of LPS-unresponsive mice (C3H/HeJ) verified that the effect of PGN pretreatment was not due to any LPS contamination. We have previously demonstrated that PGN pretreatment induced resistance to a Gram-positive bacterial challenge. The present study extends those results by showing that exposure to the Gram-positive bacterial cell wall component peptidoglycan also induces cross-tolerance to LPS and non-specifically enhances innate immune function in that PGN-pretreated mice had increased resistance to Gram-negative bacterial challenge.
Microbes and Infection 08/2008; 10(12-13):1244-50. DOI:10.1016/j.micinf.2008.07.021 · 2.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We studied the effects of tolerance induced by Escherichia coli-derived LPS on the innate immune response to a subsequent Staphylococcus aureus bacterial challenge. LPS tolerance was induced in wild-type mice by either intraperitoneal or intravenous injection of 2 microg of LPS on 2 consecutive days. Mice were challenged with an intravenous injection of live S. aureus (5 x 10(8) colony-forming units) 2 days after the second LPS dose. LPS-tolerant mice had a diminished serum interferon-gamma response to the bacterial challenge. Bacterial counts in liver and spleen tissues were decreased, and survival was improved after the Staphylococcus challenge in LPS-tolerant mice compared with saline-pretreated control mice. LPS pretreatment by the intravenous route was also associated with a decreased number of bacterial colonies in lung tissue in addition to liver and spleen, suggesting that induction of LPS tolerance was somewhat compartmentalized after intraperitoneal LPS pretreatment. Induction of tolerance seemed to be due to LPS-specific signaling because LPS pretreatment of LPS-nonresponsive C3H/HeJ mice did not provide similar effects after bacterial challenge. Flow cytometric analysis of spleens from LPS-tolerant mice revealed an increase in phagocytic cells (neutrophiles and macrophages) compared with control mice. Ex vivo culture of splenocytes from LPS-tolerant mice demonstrated increased uptake of fluorescein isothiocyanate-tagged ovalbumin, but no difference in either phagocytosis of fluorescein isothiocyanate-labeled Staphylococcus or bactericidal activity could be demonstrated on a per-cell basis. These results show that attenuation of inflammation and mortality during LPS tolerance extends to gram-positive bacterial organisms and suggests that LPS-induced enhancement of the innate immune response may be attributed to increased numbers of phagocytic cells.
[Show abstract][Hide abstract] ABSTRACT: The present study was undertaken to determine whether the mice depleted of alphabeta or gammadelta T cells show resistance to acute polymicrobial sepsis caused by cecal ligation and puncture (CLP). T-cell receptor beta knockout (betaTCRKO) and T-cell receptor delta knockout (deltaTCRKO) mice were used. An additional group of mice was treated with an antibody against the alphabeta T-cell receptor to induce alphabeta T-cell depletion; a subset of alphabeta T cell-deficient mice was also treated with anti-asialoGM1 to deplete natural killer (NK) cells. The mice underwent CLP and were monitored for survival, temperature, acid-base balance, bacterial counts, and cytokine production. The betaTCRKO mice and the wild-type mice treated with anti-beta T-cell receptor (anti-TCRbeta) antibody showed improved survival after CLP compared with wild-type mice. The treatment of alphabeta T cell-deficient mice with anti-asialoGM1further improved survival after CLP, especially when the mice were treated with imipenem. The improved survival observed in alphabeta T cell-deficient mice was associated with less hypothermia, improved acid-base balance, and decreased production of the proinflammatory cytokines interleukin (IL) 6 and macrophage inflammatory protein (MIP) 2. Compared with wild-type controls, the overall survival was not improved in deltaTCRKO mice. The concentrations of IL-6 and MIP-2 in plasma and cytokine mRNA expression in tissues were not significantly different between wild-type and deltaTCRKO mice. These studies indicate that mice depleted of alphabeta but not of gammadelta T cells are resistant to mortality in an acutely lethal model of CLP. The depletion of NK cells caused further survival benefit in alphabeta T cell-deficient mice. These findings suggest that alphabeta T and NK cells mediate or facilitate CLP-induced inflammatory injury.
[Show abstract][Hide abstract] ABSTRACT: Endotoxin (LPS) tolerance is induced by exposure to sublethal doses of LPS, resulting in a suppressed proinflammatory response and an improved survival rate after challenge with a normally lethal dose of LPS. We studied the effects of tolerance induced by either Escherichia coli-derived LPS or Pseudomonas aeruginosa-derived LPS on the innate immune response to a subsequent P. aeruginosa bacterial challenge and determined if the induction of tolerance was dependent on interferon gamma (IFN-gamma) activity. LPS tolerance was induced in wild-type (WT) and IFN-gamma knockout mice by i.p. injection of 1 microg of LPS on 2 consecutive days. Mice were challenged with an i.p. injection of live P. aeruginosa (1 x 10(8) colony-forming units) 2 days after the second LPS dose. LPS tolerance in WT mice was associated with diminished serum IFN-gamma and IL-12 and increased serum IL-10 responses to the Pseudomonas challenge. Both clearance of the bacterial challenge and survival were improved in WT animals pretreated with either E. coli LPS or P. aeruginosa LPS compared with saline-pretreated control mice. Similarly, IFN-gamma knockout mice exposed to LPS before the Pseudomonas challenge also had improved bacterial clearance of the challenge and an improved survival rate. In separate experiments, priming with IFN-gamma at a dose that approximated the serum concentration induced by LPS priming did not alter cytokine production or bacterial clearance after a Pseudomonas challenge. Finally, administration of IFN-gamma at the time of Pseudomonas challenge amplified cytokine production in LPS-tolerant animals but did not affect bacterial clearance. These results suggest that IFN-gamma is not necessary for the induction of LPS tolerance. Furthermore, IFN-gamma seems to play a role in propagating the inflammatory cytokine response to Pseudomonas challenge, but it did not seem to have any role in bacterial clearance.
[Show abstract][Hide abstract] ABSTRACT: Immunocompromise after a major injury is presumed to be a predisposing factor for sepsis. Mice subjected to sublethal cecal ligation and puncture (CLP) and challenged 5 days later with Pseudomonas aeruginosa had more bacterial growth in lung tissue, lower serum interferon gamma (IFN-gamma) and interleukin (IL) 12,and higher serum IL-10 when compared with sham CLP mice challenged with Pseudomonas. To test the functional significance of these alterations in cytokine production in the immune response to bacteria, we administered IFN-gamma and anti-IL-10 to post-CLP mice before the Pseudomonas challenge. Administration of IFN-gamma and anti-IL-10 did not improve bacterial clearance or mortality in post-CLP mice. In further studies, we administered IFN-gamma to IL-10 knockout mice before a challenge with P. aeruginosa. Our results showed no significant differences in bacterial clearance or mortality in IL-10 knockout mice with or without IFN-gamma treatment compared with wild-type controls. Finally, because most mortality occurred within 2 to 3 days of the Pseudomonas challenge in the aforementioned studies and was likely associated with a marked proinflammatory response, we investigated the effect of IFN-gamma and anti-IL-10 on clearance of Pseudomonas in C3H/HeJ mice, which do not mount an exaggerated proinflammatory response to endotoxin or Gram-negative bacteria. Neither clearance of the Pseudomonas bacteria nor mortality was improved in C3H/HeJ mice receiving anti-IL-10 and IFN-gamma. These results suggest that the suppressed IFN-gamma and IL-12 responses, in combination with an exaggerated IL-10 response to P. aeruginosa challenge after injury, do not correlate with bacterial clearance or survival.
[Show abstract][Hide abstract] ABSTRACT: Transforming growth factor-beta (TGF-beta), a cytokine with anti-inflammatory properties, may contribute to postburn immunosuppression. This study was designed to determine whether neutralizing TGF-beta in burned mice could improve resistance to infection. C57BL/6J mice received a 35% TBSA flame burn under isoflurane anesthesia. Four days after injury, mice were treated with TGF-beta antibody or nonspecific IgG. On day 5 after burn injury, mice were inoculated with Pseudomonas aeruginosa at the burn wound site or received intraperitoneal injection with P. aeruginosa. Mice treated with anti-TGF-beta exhibited significantly improved survival compared with mice treated with nonspecific IgG after challenge with P. aeruginosa at the burn wound site or after intraperitoneal injection of P. aeruginosa. In mice with burn wound infections, bacterial counts in burn wounds, blood, and lung were decreased in mice treated with anti-TGF-beta compared with mice treated with control IgG. Bacterial counts in lung and blood after intraperitoneal challenge with P. aeruginosa also were significantly lower in burned mice treated with anti-TGF-beta compared with those treated with nonspecific IgG. Our data suggest that neutralization of TGF-beta at 4 days after burn injury in mice improves local and systemic clearance of P. aeruginosa and enhances survival after P. aeruginosa challenge.
Journal of burn care & research: official publication of the American Burn Association 01/2006; 27(5):682-7. DOI:10.1097/01.BCR.0000238083.95170.2A · 1.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Endotoxin (lipopolysaccharide [LPS]) tolerance is an altered state of immunity caused by prior exposure to LPS, in which production of many cytokines, including gamma interferon (IFN-gamma) and interleukin-12 (IL-12), are reduced but secretion of the anti-inflammatory cytokine IL-10 is increased in response to a subsequent LPS challenge. This pattern of cytokine production is also characteristic of postinflammatory immunosuppression. Therefore, we hypothesized that LPS-primed mice would exhibit an impaired ability to respond to systemic infection with the opportunistic pathogen Pseudomonas aeruginosa. We further hypothesized that depletion of IL-10 would reverse the endotoxin-tolerant state. To test this hypothesis, systemic clearance of Pseudomonas aeruginosa was measured for LPS-primed wild-type and IL-10-deficient mice. LPS-primed wild-type mice exhibited significant suppression of LPS-induced IFN-gamma and IL-12 but increased IL-10 production in blood and spleen compared to levels exhibited by saline-primed wild-type mice. The suppressed production of IFN-gamma and IL-12 caused by LPS priming was ablated in the spleens, but not blood, of IL-10 knockout mice. LPS-primed wild-type mice cleared Pseudomonas aeruginosa from lungs and blood more effectively than saline-primed mice. LPS-primed IL-10-deficient mice were particularly efficient in clearing Pseudomonas aeruginosa after systemic challenge. These studies show that induction of LPS tolerance enhanced systemic clearance of Pseudomonas aeruginosa and that this effect was augmented by neutralization of IL-10.
Infection and Immunity 12/2005; 73(11):7340-7. DOI:10.1128/IAI.73.11.7340-7347.2005 · 4.16 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: These studies evaluated the effects treatment with glucan phosphate, a soluble polysaccharide immunomodulator, on the inflammatory response induced by burn injury and on resistance to Pseudomonas aeruginosa burn wound infection. Mice were exposed to 35% total body surface area burns and were resuscitated with lactated Ringer's (LR) solution alone or LR supplemented with glucan phosphate (40 mg/kg). Glucan phosphate treatment attenuated burn-induced expression of interleukin (IL)-1beta, IL-6, and IL-10 mRNAs in spleen, lung, and heart. Plasma concentrations of IL-1beta, IL-6, macrophage inflammatory protein (MIP)-2, and IL-10 were also decreased in burned mice treated with glucan phosphate compared with vehicle-treated controls. Early postburn mortality was not significantly different between control (20%) and glucan phosphate-treated (10%) mice, but there was a small improvement in acid-base balance in the glucan phosphate-treated group. Mice received a second injection of glucan phosphate or LR on day 4 postburn and were infected by topical application of P. aeruginosa to the burn wound on day 5. Glucan phosphate treatment significantly improved survival in mice exposed to P. aeruginosa burn wound infection. The improved survival correlated with lower bacterial burden in the burn wound, attenuated production of proinflammatory cytokines, and enhanced production of Th1 cytokines. These studies show that glucan phosphate treatment attenuates burn-induced inflammation and increases resistance to P. aeruginosa burn wound infection in an experimental model of burn injury.
[Show abstract][Hide abstract] ABSTRACT: Fms-like tyrosine kinase-3 ligand (Flt3L) is a hemopoietic cytokine that stimulates the production of dendritic cells. This study evaluated the ability of Flt3L-enhanced dendritic cell production to increase the resistance of mice to a burn wound infection with Pseudomonas aeruginosa, a common source of infections in burn patients that have impaired immunity and are susceptible to opportunistic microorganisms. Treatment of mice with Flt3L for 5 days caused a significant increase in dendritic cell numbers in the spleen and significantly increased survival upon a subsequent burn wound infection. Improved survival in Flt3L-treated mice was associated with limited bacterial growth and spread within the burn wounds and a decrease in systemic dissemination of P. aeruginosa. Resistance to burn wound infection could also be conferred to recipient mice by the adoptive transfer of dendritic cells that had been isolated from spleens of Flt3L-treated mice. Adoptive transfer of the same number of splenic dendritic cells from nontreated mice did not confer resistance to burn wound infection. These data indicate that Flt3L can increase the resistance of mice to a P. aeruginosa burn wound infection through both stimulation of dendritic cell production and enhancement of dendritic cell function.
The Journal of Immunology 02/2005; 174(1):404-10. DOI:10.4049/jimmunol.174.1.404 · 5.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Patients that have suffered a major injury may sustain a period of immunocompromise and altered Th1/Th2 cytokine balance that can predispose them to opportunistic infections. Pseudomonas aeruginosa is frequently a causative organism for nosocomial infections in critically ill patients and is associated with high mortality. We previously mimicked this clinical scenario by challenging mice with P. aeruginosa 5 days after a cecal ligation and puncture (CLP) procedure. Mice that were subjected to CLP had reduced ability to clear bacteria, significantly lower gamma interferon (IFN-gamma) concentrations in plasma, and significantly elevated levels of interleukin 10 (IL-10) in plasma in response to the Pseudomonas challenge compared to uninjured control mice. We investigated the significance of the alteration in IFN-gamma by administering recombinant IFN-gamma to post-CLP mice at the time of Pseudomonas challenge and by challenging IFN-gamma knockout (IFN-gamma KO) mice with Pseudomonas. Administration of IFN-gamma to post-CLP mice attenuated IL-10 secretion and enhanced IL-12 secretion but did not improve bacterial clearance or survival after Pseudomonas challenge. Furthermore, IFN-gamma KO mice had significantly higher plasma IL-10 concentrations but did not exhibit impaired bacterial clearance or increased mortality following Pseudomonas challenge. These data indicate that systemic administration of IFN-gamma effectively reverses alterations in immune function that are commonly associated with immunosuppression in critically injured mice but does not improve bacterial clearance or survival following Pseudomonas challenge. Further, endogenous IFN-gamma does not appear to contribute significantly to early clearance of Pseudomonas bacteremia, nor does it affect the mortality rate after a lethal Pseudomonas challenge.
Infection and Immunity 01/2005; 72(12):6892-901. DOI:10.1128/IAI.72.12.6892-6901.2004 · 4.16 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We previously showed that beta 2 microglobulin knockout mice depleted of NK cells by treatment with anti-asialoGM1 (beta2MKO/alphaAsGM1 mice) are resistant to sepsis caused by cecal ligation and puncture (CLP). beta2MKO mice possess multiple immunological defects including depletion of CD8+ T cells. This study was designed to determine the contribution of CD8+ T and NK cell deficiency to the resistance of beta2MKO/alphaAsGM1 mice to CLP-induced injury. beta2MKO/alphaAsGM1 mice and CD8 knockout mice treated with anti-asialoGM1 (CD8KO/alphaAsGM1 mice) survived significantly longer than wild-type mice following CLP. Improved long-term survival was also observed in wild-type mice rendered CD8+ T/NK cell-deficient by treatment with both anti-CD8alpha and anti-asialoGM1. Blood gas analysis and body temperature measurements showed that CD8+ T and NK cell-deficient mice have significantly reduced metabolic acidosis and less hypothermia compared to control mice at 18 h after CLP. CD8+ T/NK cell-deficient mice also showed an attenuated proinflammatory response as indicated by decreased expression of mRNAs for IL-1, IL-6 and MIP-2 in spleen and heart. IL-6, KC and MIP-2 levels in blood and peritoneal fluid were also significantly decreased CD8+ T/NK cell-deficient mice compared to controls. CD8+ T/NK cell-deficient mice exhibited decreased bacterial concentrations in blood, but not in peritoneal fluid or lung, compared to wild-type controls. These data show that mice depleted of CD8+ T and NK cells exhibit survival benefit, improved physiologic function and an attenuated proinflammatory response following CLP that is comparable to beta2M/alphaAsGM1 mice.
[Show abstract][Hide abstract] ABSTRACT: Introduction. Severe injury associates with immune suppression and increased susceptibility to sepsis, frequently resulting in MODS. Previous study showed thermal injury induces significant increase in plasma TGF-β1 that might contribute to post-trauma immunosuppression. This study tried to verify whether neutralizing the murine plasma TGF-β1 following burn injury could lead to improvement of bacterial clearance. Methods. Female C57BL/6J mice, 6–8 weeks old, received a 40% total body surface area (TBSA) burn under 2.5% isoflurane inhalation anesthesia. Mice were divided into four groups: Sham control with TGF-β1 antibody treatment (Sham + TGFbAb), sham with non-specific IgG treatment (Sham + IgG), burn with TGF-β1 antibody treatment (B + TGFbAb), and burn with IgG treatment (B + IgG). Mice were resuscitated with lactated Ringer’s solution 0.1 ml/g intraperitoneally and buprenorphine (2 mg/kg subcutaneous) was given for analgesia. Sham and burned mice were subjected to septic challenge with intraperitoneal injection of 5 × 107 colony forming units (CFU) of Pseudomonas aeruginosa (PA) on postburn day 5 and sacrificed 6 hours later. The whole lungs were collected aseptically from all animals at sacrifice and homogenized in sterile saline. Serial dilutions were plated in tryptic soy agar. CFU were counted after 24 h of incubation. Data are expressed as means ± SEM, and significance was accepted at P < 0.05. Results. Our data showed that TGF-β1 antibody-treated burn mice has no bacteria grown on the plate (0/6), but TGF-β1 antibody treated sham mice has significant bacteria growth (6/6). (P = 0.022 < 0.05) The bacteria growth with the IgG-isotype-treated groups sits in-between (2/5 each). Conclusion. Our data showed neutralization of TGF-β1 significantly improved the bacterial clearance in burned mice, but worsened clearance in the sham mice. These phenomena indicate that plasma TGF-β plays a key role in immune homeostasis. To keep the optimal level of TGF-β1 is the key to maintaining effective bacterial clearance.
Journal of Surgical Research 10/2004; 121(2):313-313. DOI:10.1016/j.jss.2004.07.150 · 2.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: After a major illness or injury, immune status in critically ill patients may fluctuate between a marked proinflammatory response and an immunosuppressed state. Postinflammatory immunosuppression can result in increased susceptibility to infection. Alterations of cytokine production, such as suppression of IFNgamma and elevation of the anti-inflammatory cytokine IL-10, are believed to contribute to postinflammatory immunosuppression. We examined antimicrobial immunity in mice that had previously been subjected to a sublethal cecal ligation and puncture (CLP) as a model of major injury. Mice were challenged with Pseudomonas aeruginosa (5 x 10(7) CFU i.v.) on day 5 after CLP or sham surgery. Bacterial clearance in mice after CLP was impaired and associated with decreased production of IFNgamma and increased production of IL-10 in the early response to the Pseudomonas challenge. Pseudomonas-induced production of the IFNgamma-inducing factor IL-12 was also decreased in post-CLP mice. However, splenocytes from post-CLP mice remained responsive to exogenous stimulation with the IFNgamma-inducing cytokines IL-12, IL-15, and IL-18 as well as T-cell receptor activation. Furthermore, production of the proinflammatory cytokines TNF-alpha, IL-1beta, and IL-6 were as high, or higher, in the post-CLP group compared with sham mice after P. aeruginosa challenge. Blockade of IL-10 did not reverse IL-12 and IFNgamma suppression in splenocytes from post-CLP mice. These studies show that suppressed bacterial clearance in post-CLP mice is associated with decreased production of IFNgamma and IL-12 and with increased production of IL-10 and proinflammatory cytokines.