Injury induces deficient interleukin-12 production, but interleukin-12 therapy after injury restores resistance to infection

OBJECTIVE: To assess at serial intervals the production of interleukin-12 (IL-12) by monocytes/macrophages from the peripheral blood of injured patients and control subjects, and using a mouse model to confirm human findings and explore the effectiveness of low-dose IL-12 therapy in restoring resistance to infection after injury. SUMMARY BACKGROUND DATA: Serious injury is associated with loss of function of the T helper 1 lymphocyte phenotype, but little is known about IL-12 production in injured patients. The authors previously reported that early, moderate-dose IL-12 therapy in a mouse model of burn injury restored resistance to a later infectious challenge (cecal ligation and puncture, CLP). However, the efficacy of clinically relevant low-dose IL-12 therapy carried out to or beyond the time of septic challenge remains to be tested. METHODS: Peripheral blood mononuclear cells (PBMCs) and adherent cells were obtained from 27 patients with major burns or traumatic injury and 18 healthy persons and were studied at serial intervals for IL-12 production stimulated by bacterial lipopolysacharide (LPS). PBMCs from 18 of the same patients were studied for IL-10 production as well. IL-12 production by adherent cells from the spleens of burn or sham burn mice was studied at serial intervals after injury to confirm the human findings. Low-dose IL-12 or vehicle was given every other day to groups of burn and sham burn mice, which were then challenged with CLP on day 10, and survival was determined. Finally, spleens were harvested from burn or sham burn animals receiving low-dose IL-12 or vehicle after CLP. After splenic cellularity was determined by hemocytometer, splenocytes were cultured and production of tumor necrosis factor-alpha, interferon-gamma, and IL-10 were assessed by immunoassay. RESULTS: Adherent cells from patients' PBMCs produced significantly less IL-12 than normal PBMCs after injury, reaching a nadir 8 to 14 days after injury. Stimulation of whole PBMCs by LPS indicated that at 8 to 14 days after injury, IL-12 production by PBMCs was significantly lower and IL-10 production was significantly higher than that of PBMCs from healthy persons. Low-dose IL-12 therapy significantly increased survival after CLP. Splenocytes from burn mice treated with IL-12 had significantly increased production of TNF-alpha and IF-beta, both before and after CLP, when compared with vehicle-treated burn animals. IL-10 production by bum splenocytes remained high after IL-12 treatment. Splenic cellularity increased after IL-12 treatment in burn mice. CONCLUSION: The capacity to produce IL-12 by adherent cells of the monocyte/macrophage lineage is significantly reduced after serious injury in humans and in a mouse burn model. In humans, there is a reciprocal relation between diminished IL-12 production and increased IL-10 production at approximately 1 week after injury. Low-dose IL-12 therapy in the mouse burn model markedly increased survival after a septic challenge, even when treatment was carried beyond the onset of sepsis. Low-dose IL-12 treatment in the mouse increased production of proinflammatory mediators important in host defense and at the same time maintained or increased production of IL-10, an important antiinflammatory cytokine.     

Is circulating endotoxin the trigger for the systemic inflammatory response syndrome seen after injury?

OBJECTIVE: Patients with severe traumatic or burn injury and a mouse model of burn injury were studied early after injury to determine the relation of plasma endotoxin (lipopolysaccharide [LPS]) to the production of proinflammatory cytokines and subsequent resistance to infection. SUMMARY BACKGROUND DATA: Elevated levels of plasma LPS have been reported in patients after serious injury. It has been suggested that circulating LPS may be a trigger for increased proinflammatory cytokine production and may play a role in the septic syndromes seen in a substantial portion of such patients. Yet, despite multiple reports of leakage of LPS from the gut and bacterial translocation after injury in animal models, there is little direct evidence linking circulating LPS with production of inflammatory mediators. METHODS: The authors studied serial samples of peripheral blood from 10 patients with 25% to 50% surface area burns and 8 trauma patients (injury Severity Score, 25-57). Patients were compared with 18 healthy volunteers. The study was focused on the first 10 days after injury before the onset of sepsis or the systemic inflammatory response syndrome. Plasma samples were assayed for LPS, and adherent cells from the blood were studied for basal and LPS-stimulated production of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and interleukin-6 (IL-6). The correlation of increased plasma LPS with TNF-alpha production was studied as was the association of increased plasma LPS and increased TNF-alpha production with subsequent septic complications. We also studied a mouse model of 25% burn injury. Burn mice were compared with sham burn control subjects. Plasma samples were assayed at serial intervals for LPS, and adherent cells from the spleens were studied for basal- and LPS-stimulated production of TNF-alpha, IL-1 beta, and IL-6. Expression of the messenger RNAs for IL-1 beta and TNF-alpha also was measured. The relation of increased TNF-alpha production with mortality from a septic challenge, cecal ligation and puncture (CLP), was determined. Finally, the effect of administration of LPS to normal mice on subsequent mortality after CLP and on TNF-alpha production was studied. RESULTS: Elevated plasma LPS (> 1 pg/mL) was seen in 11 of the 18 patients within 10 days of injury and in no normal control subjects. In this period, patients as compared with control subjects showed increased stimulated production of TNF-alpha, IL-1 beta, and IL-6. Increased TNF-alpha production was not correlated with elevated plasma LPS in the same patients. Neither increased plasma LPS nor increased TNF-alpha production early after injury was correlated with subsequent development of systemic inflammatory response syndrome or sepsis in the patients. Burn mice, as compared with sham burn control subjects, showed elevated plasma LPS levels chiefly in the first 3 days after injury. Increased stimulated production of proinflammatory cytokines by adherent splenocytes from the burn mice also was seen at multiple intervals after injury and did not correlate with mortality from CLP. Increased production of TNF-alpha and IL-1 beta was associated with increased expression of messenger RNAs for these cytokines. Finally, two doses of 1 ng LPS administered 24 hours apart to normal mice had no effect on mortality from CLP performed 7 days later nor on the production of TNF-alpha at the time of CLP. CONCLUSIONS: These findings call into question the idea that circulating LPS is the trigger for increased proinflammatory cytokine production, systemic inflammatory response syndrome, and septic complications in injured patients.     

Temporal correlation of impaired immune response after thermal injury with susceptibility to infection in a murine model

Suppression of cellular immunity and increased susceptibility to sepsis frequently accompany thermal injury. However, a convincing association between the two has been difficult to establish in human beings. Therefore we chose to investigate the relationship of impaired cell-mediated immunity with susceptibility to sepsis in an animal model. We studied the response to phytohemagglutinin (PHA) and interleukin-2 (IL-2) production by splenocytes from mice subjected to a standard 25% scald burn and killed at intervals of 3, 5, 7, 10, 14, and 25 days after thermal injury. Burned mice were compared in all instances to sham-burn animals (i.e., animals that had been anesthetized and shaved but not burned). We also studied mortality after cecal ligation and puncture (CLP), as a septic challenge, in burned and control animals at the same postburn intervals. We found maximal suppression (50% to 55%) of the PHA response at 10 to 14 days after injury and maximum suppression (68%) of IL-2 production at 7 days. Both of these parameters returned to normal by postinjury day 28. Mortality after CLP increased gradually from control levels after thermal injury up to a maximum of 88% on postburn day 10 and also returned to control levels after 28 days after burn. Significant correlations were found between mortality after CLP in the postburn period and suppression of the PHA response, on the one hand, and the suppression of IL-2 production, on the other (r = 0.89 and 0.91, respectively; p less than 0.05). This result implies a causal relationship between impaired cell-mediated immunity and susceptibility to sepsis after burn injury.     

δ阿片受体激动剂对脓毒症大鼠细胞免疫功能的影响

目的 探讨δ阿片受体激动剂对脓毒症大鼠细胞免疫功能的影响.方法 健康成年雄性SD大鼠150只,体重154～198g,随机分为3组(n=50):假手术组(S组)仅穿线,不进行盲肠结扎穿孔;脓毒症组(SEP组)采用盲肠结扎穿孔的方法制备脓毒症模型;δ阿片受体激动剂组(DADLE组)于盲肠结扎穿孔后立即腹腔注射δ阿片受体激动剂DALDE 10 ml/kg,浓度为0.5 mg/ml.于盲肠结扎穿孔后4、8、12 h(T1～3)时各组随机取10只大鼠,抽取下腔静脉血样,采用ELISA法检测血清TNF-α和IL-10的浓度,采用流式细胞仪检测T淋巴细胞亚群变化.记录盲肠结扎穿孔后7 d内大鼠的生存情况.结果 与S组比较,SEP组和DADLE组各时点血清TNF-α和IL-10的浓度、TNF-α/lL-10比值升高,T3时CD4+T细胞水平和CD4+/CD8+降低,CD8+T细胞水平升高(P＜0.05或0.01);与SEP组比较,DADLE组T2.3时血清TNF-α和IL-10的浓度、TNF-α/IL-10比值降低,T3时CD4+T细胞水平和CD4+/CD8+升高,CD8+T细胞水平降低,盲肠结扎穿孔后7 d内大鼠生存率升高(P＜0.05).结论 δ阿片受体激动剂可改善细胞免疫功能,从而减轻炎性反应,有利于脓毒症大鼠的预后.     

Mechanism of immune dysfunction in sepsis: inducible nitric oxide-meditated alterations in p38 MAPK activation

BACKGROUND: After the onset of sepsis, there is a marked dysfunction in cell-mediated immunity that contributes to the morbidity and mortality seen in this condition. Although both nitric oxide (NO) from inducible NO synthase (iNOS) and the activation of p38 mitogen-activated protein kinase (p38 MAPK) appear to contribute to this immune dysfunction, the extent to which NO regulates p38 MAPK activity in sepsis remains unknown. METHODS: To examine this, we induced sepsis by cecal ligation and puncture (CLP) in iNOS knockout (iNOS -/-) or C57BL/6 control mice. Twenty-four hours after CLP or sham operation, splenic T cells and macrophages were isolated and then stimulated with monoclonal antibody against the T-cell marker CD3 (anti-CD3) or lipopolysaccharide. At 4 or 24 hours after stimulation, cytokine release was determined by enzyme-linked immunosorbent assay, and p38 MAPK phosphorylation (activation) was determined by immunoblotting with antibody specific to phosphorylated p38 MAPK. RESULTS: Splenic T-cell p38 MAPK activation and interleukin (IL)-10 release was increased by CLP, whereas Th1 cytokine (IL-2, interferon-gamma) release was depressed. iNOS gene deficiency inhibited p38 MAPK activation in splenic T cells taken from septic mice, and also suppressed IL-10 release in both sham and septic mice. Interestingly, although deficiency of iNOS restored IL-2 release after CLP, both sham and CLP T cells remained depressed in their ability to release interferon-gamma. Septic insult markedly suppressed C57BL/6 splenic macrophage release of proinflammatory agents tumor necrosis factor, IL-12, and IL-1, while augmenting the release of IL-10. However, although deficiency of iNOS concomitantly restored the ability to produce tumor necrosis factor while suppressing the rise in IL-10 release and p38 MAPK activation, it only partially restored IL-1 release and had no effect on IL-12 production seen after CLP. CONCLUSION: These data suggest that NO release from iNOS regulates aspects of sepsis-induced immune dysfunction by the activation of p38 MAPK.     

Interleukin-12 and -18 induce severe liver injury in mice recovered from peritonitis after sublethal endotoxin challenge

BACKGROUND: Postoperative intraabdominal abscess is the major complication after abdominal surgery, and additional infection is often observed and becomes the leading cause of death in septic patients who survive initial resuscitation. Sepsis is initiated and perpetuated by the overzealous systemic production of proinflammatory cytokines-such as tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-12, and IL-18-sometimes resulting in excessive tissue injury and death. The purpose of this study was to assess the correlation between liver and spleen innate cytokine responses and organ dysfunction in sepsis syndrome. METHODS: Peritonitis was induced by cecal ligation and puncture (CLP). All CLP mice survived more than 7 days after the procedure, and serum cytokine (TNF-alpha, IL-12, IL-18, and IL-10) levels peaked 12 hours after CLP; thereafter, they returned to basal levels 7 days after CLP. The mice were injected with a sublethal dose of lipopolysaccharide (LPS) 7 days after CLP. Survival rates, tissue damage, serum cytokine levels, and cytokine production of liver or spleen mononuclear cells (MNCs) were evaluated. RESULTS: All CLP mice died within 6 hours from liver injury 7 days after LPS challenge, but all sham mice survived. IL-12, IL-18, and IFN-gamma levels in supernatants of the liver MNCs stimulated with LPS in CLP mice were significantly higher than those in sham mice 7 days after the procedure. Furthermore, serum IL-12 and IL-18 levels and liver MNCs IL-12, IL-18, and IFN-gamma production were significantly increased in CLP mice compared with sham mice after LPS challenge. Thereafter, effects of anti-IL-12 and/or anti-IL-18 antibody were evaluated in LPS-injected CLP mice. The survival rate of LPS-injected CLP mice treated with both anti-IL-12 and anti-IL-18 antibody was significantly better than that of untreated mice. Furthermore, liver damage was improved. CONCLUSION: Mice recovered from mild peritonitis died of severe liver injury by subsequent injection of a sublethal dose of LPS, and this liver injury was related to the collaborating production of IL-12 and IL-18 by liver MNCs.     

Suppressor T-cell levels are unreliable indicators of the impaired immune response following thermal injury.

The presence of increased levels of suppressor T cells after thermal injury and their relevance remain controversial. It is unclear whether suppressor T cells are the cause or result of sepsis complicating thermal injury. Spleen cells from a standardized murine burn model and sham burn controls were studied and the relationship between the levels of suppressor cytotoxic T cells (CD8, Lyt-2+), helper T cells (CD4, L3T4+), response to concanavalin A (ConA) and to phytohemagglutinin (PHA) and interleukin-2 (IL-2) production was examined. Mortality following infection via cecal ligation and puncture (CLP) of matched controls was also studied. At day 7 postburn, mean ConA (70 +/- 12% of control) and PHA response (58% +/- 5.2% of controls) and IL-2 production (43% +/- 5.4%) were significantly less than sham burn values (100%; p less than 0.05). However, the mean percentage of cells staining with anti-Lyt-2 and anti-L3T4 (9.1 +/- 0.59 and 13.9 +/- 0.65) was similar to the mean percentage in sham burn animals (9.4 +/- 0.65 and 16.6 +/- 1.1). Furthermore, no significant differences were observed between burned mice and controls in helper (17.3% +/- 1.8% burn vs. 21.2% +/- 1.7% sham) or suppressor cell levels (7.8% +/- 1.2% burn vs. 8.6% +/- 0.7% sham) or helper-suppressor ratios on day 10 postburn. Mortality of 20 litter-matched controls subjected to CLP on day 10 postburn was 90%, which was significantly greater than the sham burn mortality of 20%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Interleukin 10 is not essential for survival or for modulating T-cell function after injury.

BACKGROUND: Interleukin 10 (IL-10) is thought to be protective in injury and sepsis. However, we recently reported that IL-10 antagonism can be beneficial after burn injury. This study used IL-10-deficient (IL-10 [-/-]) mice to further define the role of IL-10 after injury. METHODS: Wild-type (WT) C57BL/6 or IL-10 (-/-) mice were anesthetized, sham or burn injured, and immunized subcutaneously with a T-cell-dependent protein antigen. Ten days later antigen-specific serum antibody isotype formation was measured by enzyme-linked immunosorbent assay. In addition, antigen-stimulated splenic T-cell proliferation and cytokine production (interleukin 2, interferon gamma, and tumor necrosis factor-alpha) were measured. RESULTS: Burn-injured IL-10 (-/-) mice survival (80%) was equivalent to that of burn-injured WT mice (74%). An injury-dependent loss of T-helper 1 (Th1)-type antibody isotype (IgG2a) formation occurred in both WT and IL-10 (-/-) mice. In vitro studies indicated that burn injury caused reduced antigen-stimulated splenic T-cell proliferation and Th1-type (interleukin 2 and interferon gamma) cytokine production in WT and IL-10 (-/-) mice, whereas burn-injured IL-10 (-/-) mice produced high levels of antigen-stimulated tumor necrosis factor-alpha. CONCLUSIONS: IL-10 is not essential for survival after burn injury or for several injury-induced changes in adaptive immune function, including Th1-type antibody isotype formation, T-cell proliferation, and Th1-type cytokine production.     

The effect of burn injury on CD8+ and CD4+ T cells in an irradiation model of homeostatic proliferation

BACKGROUND: Homeostatic proliferation of T cells has recently been shown to be an important mechanism in the host response to infection. However, its role in the T cell response to burn injury is unknown. In this study, we examine the effect of burn injury on CD4+ and CD8+ T cell homeostatic proliferation after irradiation. METHODS: Wild-type C57BL/6 female mice were irradiated with six grays ionizing radiation and 48 hours later, syngeneic whole splenocytes or purified CD4+ or CD8+ T cells labeled with carboxy-fluorescein diacetate, succinimidyl ester were adoptively transferred. Two days later, mice underwent a 20% burn injury, followed by splenocyte harvest 3 and 10 days after injury. RESULTS: Burn mice demonstrate increased splenic cellularity and CD8+ T cell proliferation after adoptive transfer of either purified CD8+ cells or whole spleen populations compared with unburned (sham) mice. In contrast, CD4+ T cell proliferation after burn injury is unchanged after adoptive transfer of whole spleen cells and drastically decreased after adoptive transfer of a purified CD4+ population compared with sham mice. Ten days after burn injury CD8+ T cells continue to demonstrate greater proliferation than CD4+ T cells. CONCLUSIONS: CD8+ T cells are more robust than CD4+ T cells in their proliferative response after burn injury. In addition, CD8+ T cell proliferation appears less reliant on other immune cells than purified CD4+ T cell proliferation. These data reiterate the importance of CD8+ T cells in the initial immune response to burn injury.     

Sepsis-induced changes in macrophage co-stimulatory molecule expression: CD86 as a regulator of anti-inflammatory IL-10 response

BACKGROUND: Sepsis remains a substantial risk after surgery or other trauma. Macrophage dysfunction, as a component of immune suppression seen during trauma and sepsis, appears to be one of the contributing factors to morbidity and mortality. However, whereas it is known that the ability of macrophages to present antigen and express major histocompatibility complex MHC class II molecules is decreased during sepsis, it is not known to what extent this is associated with the loss of co-stimulatory receptor expression. Our objectives in this study were, therefore, to determine if the expression of co-stimulatory molecules, such as CD40, CD80, or CD86, on peritoneal/splenic/liver macrophages were altered by sepsis (cecal ligation [CL] and puncture [CLP] or necrotic tissue injury (CL) alone; and to establish the contribution of such changes to the response to septic challenge using mice that are deficient in these receptors. METHODS: To address our first objective, male C3H/HeN mice were subjected to CLP, CL, or sham (n = four to six mice/group), and the adherent macrophages were isolated from the peritoneum, spleen, or liver at 24 h post-insult. The macrophages were then analyzed by flow cytometry for their ex vivo expression of CD40, CD80, CD86, and/or MHC II. RESULTS: The expression of CD86 and MHC II, but not CD40 or CD80, were significantly decreased on peritoneal macrophages after the onset of sepsis or CL alone. In addition, CD40 expression was significantly increased in Kupffer cells after sepsis. Alternatively, splenic macrophages from septic or CL mice did not show changes in the expression of CD80, CD86, or CD40. To the degree that the loss of CD86 expression might contribute to the changes reported in macrophage function in septic mice, we subsequently examined the effects of CLP on CD86 -/- mice. Interestingly, we found that, unlike the background controls, neither the serum IL-10 concentrations nor the IL-10 release capacity of peritoneal macrophages from septic CD86 -/- mice were increased. CONCLUSION: Together, these data suggest a potential role for the co-stimulatory receptor CD86/B7-2 beyond that of simply promoting competent antigen presentation to T-cells, but also as a regulator of the anti-inflammatory IL-10 response. Such a role may implicate the latter response in the development of sepsis-induced immune dysfunction.     

右美托咪啶对脓毒症大鼠血清炎性因子和氧化应激反应的影响

目的 探讨右美托咪啶对脓毒症大鼠血清炎性因子和氧化应激反应的影响.方法 健康雄性SD大鼠30只,10～ 14周龄,体重250～300 g,采用随机数字表法,将其随机分为3组(n=10):假手术组(S组)、脓毒症组(CLP组)和脓毒症+右美托咪啶组(CLP+D组).CLP组和CLP+D组采用盲肠结扎穿孔术制备脓毒症模型,CLP+D组术毕静脉输注右美托咪啶10 μg·kg-1·h-1至大鼠死亡或术后12 h,S组和CLP组给予等容量生理盐水1ml·kg-1·h-1.每组取5只大鼠,分别于术前(基础状态)、术后1、6、12 h时采集股动脉血样,测定血清IL-6、IL-10、SOD及MDA的水平.记录术后12 h内大鼠生存情况.结果 与S组比较,CLP组术后1、6、12 h时血清IL-6、IL-10和MDA的浓度升高,血清SOD活性和生存率降低(P＜0.05);与CLP组比较,CLP+D组术后6、12 h时血清IL-6和MDA的浓度降低,术后12 h时血清SOD活性和生存率升高(P＜0.05).结论 右美托咪啶可以提高脓毒症大鼠的生存率,其机制与抑制炎性因子释放及氧化应激反应有关.     

Use of intracellular cytokine staining and bacterial superantigen to document suppression of the adaptive immune system in injured patients

OBJECTIVE: To determine the percentages of major T lymphocyte subsets in the circulating peripheral blood mononuclear cell population in patients with major traumatic injury at early and late time points and to determine the expression of coreceptors and cytokine production by these T cell subsets. SUMMARY BACKGROUND DATA: Prior studies suggest that serious injury in humans suppresses the adaptive immune system as revealed by diminished proliferation and altered cytokine production in response to polyclonal T cell activation. However, the contribution of individual cell types to this immune dysfunction has not been well characterized. METHODS: The percentage of circulating CD4+ and CD8+ T cells and the relative density of CD4 and CD8 coreceptor expression was determined by flow cytometry in 17 consecutive trauma patients (injury severity score > 20) within 24 hours of injury and at day 7. Intracellular expression of the cytokines interleukin 2 (IL-2), interferon gamma (IFNgamma), IL-4, and IL-10 were also studied after stimulation with bacterial superantigen (SEB). Patients were compared with age- and sex-matched controls and to themselves for differences between early and late cytokine expression. RESULTS: The percentage of circulating CD4+ and CD8+ T cells was decreased versus controls at day 1 and further decreased by day 7 following injury. CD4 and CD8 cell surface expression was also decreased at days 1 and 7. CD4+ T cells in injured patients responded to SEB activation with decreased expression of IFNgamma and IL-2 on day 1 versus controls (P < 0.05) and of all 4 cytokines by day 7 (P < 0.05), while CD8+ T cells showed diminished expression of IFNgamma and IL-2 only at both time points. When day 1 and day 7 cytokine expression results were compared in the same patients, CD4+ T cells showed diminished expression of IFNgamma, IL-2, and IL-4 by day 7 (P < 0.05), but maintained expression of IL-10. CD8 T cells showed diminished expression of IFNgamma only. CONCLUSIONS: Severe injury induces a loss of circulating CD4+ and CD8+ T lymphocytes and diminished coreceptor expression by these cells. Both T cell subsets show progressive loss of immunostimulatory cytokine production with maintenance of potentially suppressive IL-10 production. These events may have negative consequences for host defense.     

Increased CD4+ CD25+ T regulatory cell activity in trauma patients depresses protective Th1 immunity

OBJECTIVES: We recently reported increased CD4 CD25 T regulatory (Treg) activity after burn injury in mice. This study sought to determine if Tregs mediate the reduction in TH1-type immunity after serious injury in man and if Treg function is altered by injury. METHODS: Peripheral blood was withdrawn from 19 consenting adult patients (35.1 +/- 16.3 years of age) with Injury Severity Scores (ISS) 36.6 +/- 13.9 on days 1 and 7 after trauma and from 5 healthy individuals. CD4 T cells were purified and sorted into Treg (CD25(high)) and Treg-depleted populations. After activation of cells with anti-CD3/CD28 antibody, production of the TH1-type cytokine IFNgamma, TH2-type cytokines (IL-4 and IL-5), and the inhibitory cytokine IL-10 was measured using cytometric bead arrays. Treg activity was measured by in vitro suppression of autologous CD4 T cell proliferation. RESULTS: All patients survived, 9 (47%) developed infection postinjury. IFNgamma production by patient CD4 T cells was decreased on day 1 and day 7, when compared with healthy controls. However, when Tregs were depleted from the CD4 T cells, the IFNgamma production increased to control levels. Tregs were the chief source of IL-4 and IL-5 as well as IL-10. Treg suppression of T cell proliferation increased significantly from day 1 to day 7 after injury. CONCLUSIONS: We demonstrate for the first time that human Tregs are increased in potency after severe injury. Most significantly, Tregs are important mediators of the suppression of T cell activation and the reduction in TH1 cytokine production found after injury.     

Inhibition of CD1d activation suppresses septic mortality: a role for NK-T cells in septic immune dysfunction

BACKGROUND: Studies indicate that following septic insult there is development of generalized immune dysfunction in T cells, B cells and phagocytes, which is thought to contribute to morbidity and mortality. Specifically, there is a shift in the lymphocytes of septic animals toward an increased release of Th2 cytokines. NK-T cells have been shown to contribute to propagation of the Th2 response. The influence of NK-T cells on the immune response to septic challenge is poorly understood. In this study, we examine whether NK-T cells contribute to the immune dysfunction seen following the onset of polymicrobial sepsis, as produced by cecal ligation and puncture (CLP). MATERIALS AND METHODS: Male 129S1/SvImJ mice were pretreated with either rat IgG (isotypic control) or monoclonal antibody to CD1d (clone 1B1) (0.5 mg), which blocks signaling/antigen presentation via the CD1d cell surface receptor, thereby, ablating the activation and differentiation of the NK-T cells. Septic survival with and without anti-CD1d (CLP/CD1d) pretreatment was assessed. Mice sacrificed 24 h after CLP were assessed for change in splenic %NK-T cell (via flourescense activated cell sector) and for splenic, hepatic, and lymphoid/macrophage production of pro-inflammatory or anti-inflammatory cytokines (via enzyme-linked immunosorbent assay). RESULTS: Administration of anti-CD1d reduced septic mortality 35% at 6-10 d (n = 23 mice/group) (P <.05). There was a consistent increase in the %CD3(+) NK1.1(+) cell population (NK-T cells) in septic mice (1.706%), which was markedly suppressed by pretreatment with anti-CD1d (0.592%). IL-6 and IL-10 levels were suppressed by anti-CD1d in the spleen and blood. CONCLUSIONS: Together these findings imply not only that NK-T cells may play a role in mediating the immune suppression seen in bacterial sepsis, but that inhibition of their activation promotes survival to septic challenge.     

A central role for CD95 (Fas) in T-cell reactivity after injury

BACKGROUND: Recent findings indicate that severe injury primes the immune system for an enhanced and lethal proinflammatory cytokine response against bacterial-derived superantigens. This study asked whether this response to injury involves the CD95 (Fas) signaling pathway. METHODS: To assess superantigen-mediated mortality, wild-type (WT) C57BL/6 and Fas-deficient C57BL/6 lpr (-/-) (lpr) mice underwent burn or sham injury and were challenged 2 hours later with staphylococcal enterotoxin B (SEB). Spleen cells from sham and burn WT or lpr mice were stimulated in vitro with SEB to assess injury effects on IL-2, TNF-alpha, and IFN-gamma production. RESULTS: Lpr burn mice survived the SEB challenge (100% survival), while WT burn mice showed a high mortality (17% survival, P < 001, analysis of variance [ANOVA]). Sham lpr or WT mice suffered no mortality to the SEB challenge. In vitro studies demonstrated that burn lpr mice produced significantly less TNF-alpha, IFN-gamma, IL-2 than burn WT mice (P <.01, ANOVA). Burn injury markedly enhanced SEB-stimulated IFN-gamma production by WT spleen cells and CD8+ T cells, while this did not occur in SEB-stimulated lpr spleen cells. CONCLUSIONS: These findings support the hypothesis that the CD95 (Fas) signaling pathway plays an integral role in the injury-induced enhanced and lethal T-cell reactivity against bacterial superantigens.     

Prolactin modulates survival and cellular immune functions in septic mice

BACKGROUND: The immunomodulatory properties of the pituitary hormone prolactin have been demonstrated. It was proposed that prolactin is important in maintaining normal immune response in several pathological states. We investigated the effect of prolactin administration on the survival and cellular immune functions during systemic inflammation. MATERIALS AND METHODS: Male NMRI mice were subjected to laparotomy (LAP) or sepsis induced by cecal ligation and puncture (CLP). Mice were treated with either saline (LAP/saline; CLP/saline) or prolactin (LAP/PRL, CLP/RPL; 4 mg/kg s.c.). Survival of septic mice was determined 24 and 48 h after CLP. Forty-eight hours after the septic challenge, the proliferative capacity, cytokine release (IL-2, IL-6, IFN-gamma) and apoptosis of splenocytes were determined. Additionally, monitoring of circulating leukocyte distribution was performed (WBC; CD3+, CD4+, CD8+, B220+, NK1.1+, F4/80+ cells by FASCan). RESULTS: CLP was accompanied by a mortality of 47% and induced a decrease in splenocyte proliferation and apoptosis rate. Administration of prolactin significantly increased the mortality of septic mice (81%). This was paralleled by a further decrease of splenocyte proliferation and an increased splenocyte apoptosis. In addition, administration of prolactin augmented the sepsis-induced inhibition of IL-2 release, attenuated the sepsis-induced inhibition of IFN-gamma release, and did not affect the release of IL-6. However, prolactin did not affect the sepsis-induced changes of circulating leukocyte subpopulations. CONCLUSIONS: We conclude that prolactin has profound immunomodulatory properties and that administration of prolactin in pharmacological doses is associated with a decreased survival and an inhibition of cellular immune functions in septic mice.     

免疫调理对脓毒症大鼠中性粒细胞和淋巴细胞亚群的影响

目的研究免疫调理对脓毒症大鼠中性粒细胞和淋巴细胞及其亚群的影响,阐明免疫调理在脓毒症治疗中的作用。方法成功制作SD大鼠盲肠结扎穿孔（CLP）脓毒症模型,被分为假手术组、对照组和实验组,各20只。制作脓毒症模型后分别在3、12、24、48h采血待测。检查外周血涂片、白细胞总数、中性粒细胞、淋巴细胞计数和CD4^＋、CD8^＋T淋巴细胞亚群。结果实验组白细胞计数和中性粒细胞计数比对照组明显降低,而淋巴细胞计数和CD8^＋T淋巴细胞水平比对照组明显升高,P〈0．05。实验组CD8们林巴细胞水平与对照组差异无统计学意义。结论免疫调理可以明显降低脓毒症大鼠白细胞和中性粒细胞,从而减轻炎症反应。免疫调理可以提高脓毒症大鼠淋巴细胞计数和CD4^＋T淋巴细胞,从而改善免疫功能。