Adiponectin protects LPS-induced liver injury through modulation of TNF-alpha in KK-Ay obese mice

Adiponectin, an adipocytokine, has been identified in adipose tissue, and its receptors are widely distributed in many tissues, including the liver. The present study was performed to clarify the role of adiponectin in lipopolysaccharide (LPS)-induced liver injury using KK-Ay obese mice. We analyzed the effects of adiponectin pretreatment on liver injury induced by D-galactosamine/LPS (GalN/LPS) in KK-Ay obese mice. GalN/LPS treatment induced significant increases in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in the blood, apoptotic and necrotic changes in hepatocytes, and/or showed a high degree of lethality. The GalN/LPS-induced liver injury was more pronounced in KK-Ay obese mice than in lean controls. Pretreatment with adiponectin ameliorated the GalN/LPS-induced elevation of serum AST and ALT levels and the apoptotic and necrotic changes in hepatocytes, resulting in a reduction in lethality. In addition, pretreatment with adiponectin attenuated the GalN/LPS-induced increases in serum and hepatic tumor necrosis factor alpha (TNF-alpha) levels and increased peroxisome proliferator-activated receptor (PPAR) alpha messenger RNA expression in the liver. Furthermore, abdominal macrophages from KK-Ay obese mice pretreated with adiponectin in vitro exhibited decreased LPS-induced TNF-alpha production compared with controls. Finally, adiponectin pretreatment also ameliorated TNF-alpha-induced liver injury. In conclusion, these findings suggest that adiponectin prevents LPS-induced hepatic injury by inhibiting the synthesis and/or release of TNF-alpha of KK-Ay obese mice.     

Protective effect of melatonin against liver injury in mice induced by Bacillus Calmette-Guerin plus lipopolysaccharide

AIM: To investigate the effects and mechanisms of melatonin on immunological liver injury in mice.METHODS: A model of liver injury was induced by tail vein injecton of Bad#us Calmet~ Guenn (BCG) and lipopolysaccharide(LPS) in mice. Kupffer cells and hepatocytes were isolated and cultured according to a modified two-step collagenase perfusion technique. Levels of alanine aminotransferase(ALT), aspartate aminotransferase (AST) and nitric oxide(NO), content of malondiadehyde (MDA), activity of superoxide dismutase (SOD), were measured by biochemical methods.Tumor necrosis factor-α (TNF-α) activity was determined by RIA. Interleukin (IL)-1 activity was measured by thymocyte proliferation bioassay. Hepatic tissue sections were stained with hematoxylin and eosin and examined under a lightmicroscope.RESULTS: Immunological liver injury induced by BCG+LPS was successfully duplicated. Serum transaminase (ALT,AST) activities were significantly decreased by melatonin(0.25, 1.0, 4.0 mg/kg bm). Meanwhile, MDA content was decreased and SOD in liver homogenates was upregulated.Furthermore, pro-inflammatory mediators (TNF-α, IL-1, NO)in serum and liver homogenates were significantly reduced by melatonin. Histological examination demonstrated that melatonin could attenuate the area and extent of necrosis,reduce the immigration of inflammatory cells. In in vitro experiment, TNF-α was inhibited at the concentrations of 10^-8-10^-6 mol/L of melatonin, while IL-1 production of Kupffer cells induced by LPS (5 t~g/mL) was decreased only at the concentration of 10^-6 mol/L of melatonin, but no effect on NO production was observed. Immunological liver injury model in vitro was established by incubating hepatocytes with BCG- and LPS-induced Kupffer cells. Activities of ALT,TNF-α, IL-1, and MDA in supernatant were significantly increased. Melatonin had little effect on the level of ALT,but reduced the content of TNF-α and MDA at concentrations of 10^-7-10^-5 mol/L and decreased the content of IL-1 at concentrations of 10^-6-10^-5 mol/L.CONCLUSION: Melatonin could significantly protect liver injury in mice, which was related to free radical scavenging,increased SOD activity and pro-inflammatory mediators.     

Genipin prevents fulminant hepatic failure resulting in reduction of lethality through the suppression of TNF-alpha production.

Genipin is a metabolite derived from the herbal medicine Inchinko-to. Little is known about the mechanism of genipin action on acute liver injury through inflammatory cytokines. We examined the effects of genipin on production of TNF-alpha in vivo and in vitro. Mice were given GalN/LPS with or without genipin treatment. All mice not given genipin died within 12h. But in mice given genipin, 8 of 15 mice survived for 24h after GalN/LPS administration. Histologically, hepatic necrosis and inflammatory cells infiltration were significantly slight in mice given genipin. Serum AST and ALT activity were significantly lower in mice given genipin. Serum and liver homogenate TNF-alpha levels were significantly lower in mice given genipin. However, in IL-6 and IL-1beta, there were no significant differences in mice given and not given genipin. TNF-alpha, NF-kappaB activation and TNF-alpha mRNA expression in a cultured mouse macrophage-like cell line J774.1 were significantly suppressed by genipin administration. In conclusion, the present findings suggest that genipin, a metabolite derived form the herbal medicine Inchinko-to improved acute liver dysfunction by suppressive effect of TNF-alpha production.     

库普弗细胞SR表达变化与内毒素肝损伤的关系

目的 观察内毒素肝损伤过程中库普弗细胞（KC）清道夫受体（SR）表达的动态变化,进而探讨内毒素肝损伤的机理。方法 经尾静脉内注射不同剂量（1mg/kg、10mg/kg）大肠杆菌内毒素（LPS）,复制内毒素肝损伤模型,采用免疫组织化学方法观察小鼠肝脏SR表达变化;酶联免疫吸附法（ELISA）测定肝组织TNFFα、IL－6的水平,光镜观察肝组织学变化。结果 （1）内毒素肝损伤过程中,KC表面SR表达呈进行笥下调,且与内毒素呈明显的量效关系。（2）SR表达的平均光密度值（A值）与肝组织TNFα、IL－6及血清ALT、TBil呈显著的负相关。结论 内毒素肝损伤过程中,随着SR表达下调,KC对内毒素的清除作用下降,内毒素对KC的激活作用则相应增强。KC SR表达变化与肝损伤密切相关。     

Kupffer cell-dependent TNF-alpha signaling mediates injury in the arterialized small-for-size liver transplantation in the mouse

Implantation of small liver grafts causes liver injury and defective regeneration leading to graft failure. We investigated whether Kupffer cell-dependent TNF-alpha signaling contributes to this poor outcome. Partial 30% liver transplantation was performed in C57BL/6 wild-type mice (control group), and in three groups with down-regulation of the TNF-alpha pathway: (i) TNF receptor 1 knockout [TNFR-1(-/-)] mice, and mice pretreated with (ii) gadolinium chloride or (iii) pentoxifylline (PTX). Fifty-percent partial liver transplantation, a model associated with full recovery, and transplantation in IL-6 knockout [IL-6(-/-)] mice were performed in some experiments. Graft injury, regeneration, portal flow, liver microcirculation, leukocyte adhesion, and animal survival were assessed. Animal survival rates were 14% in the control group vs. 43% in the gadolinium chloride group, 57% for the TNFR-1(-/-) group, and 86% in the PTX group (P < 0.001). Markers of liver injury were reduced in all treated groups when compared with controls. Each treated group disclosed better portal flow and sinusoid perfusion, decreased leukocyte adherence, particularly in the PTX group. Liver regeneration occurred only in the treated groups. IL-6 and IL-10 levels were dramatically up-regulated (50x) in the PTX group, and at lower levels in other experimental groups. The protective effect of PTX was lost in IL-6(-/-) mice and protection was restored by a single dose of r-IL-6. In conclusion, interruption of TNF-alpha signaling or depletion of Kupffer cells improves survival after 30% liver transplantation, reduces liver injury, and enhances regeneration. The superior effects of PTX are mediated by IL-6.     

CO liberated from CORM-2 modulates the inflammatory response in the liver of thermally injured mice

AIM： To explore the effects of CO-releasing molecules [tricarbonyldichlororuthenium （Ⅱ） dimer, CORM-2]- liberated CO on attenuation of inflammatory responses in liver of an experimental animal model of thermal injury and to investigate the associated potential mechanisms. METHODS： Thirty-six mice were assigned to three groups in three respective experiments. In each experiment, mice in sham group （n = 4） received sham thermal injury, whereas mice in burn group （n = 4） received a 15% of total body surface area （TBSA） fullthickness thermal injury, and mice in burn ＋ CORM-2 group （n = 4） received the same thermal injury with immediate administration of CORM-2 （8 mg/kg, iv）. Hepatic tissue sections were stained with hematoxylin and eosin and examined under a light microscope. Levels of aminotransferases （ALT and AST） and nitric oxide （NO） were measured by biochemical methods. Tumor necrosis factor-α （TNF-α） and interleukin （IL-1β） activity, and the protein expression of iNOS and HO-1 in serum and tissue homogenates were assessed. In in vitro experiments, Kupffer cells were stimulated with LPS （10 μg/mL） for 4 h in the presence or absence of CORM-2 （10-100 μmol/L）. Subsequently, the expression levels of TNF-α and NO production were assessed. RESULTS： Pro-inflammatory mediators （TNF-α, IL- 1β, NO） in serum and liver homogenates of thermally injured mice were significantly reduced by CORM-2 administration. This was accompanied by a decrease in the expression of iNOS while an increase in the expression of HO-1 in the liver tissue. In parallel, the concentrations of TNF-α and NO in supernatants of LPS-stimulated Kupffer cells co-incubated with CORM-2 （10-100 μmol/L） were also markedly decreased.Histological examination demonstrated that CORM-2 could attenuate the leukocytes infiltration to the liver tissue. CONCLUSION： CORM-released CO modulates liver inflammation and significantly protects liver injury in burn mice by inhibiting the expression     

Deletion of the Ron receptor tyrosine kinase domain in mice provides protection from endotoxin-induced acute liver failure

The targeted deletion of the cytoplasmic domain of the Ron receptor tyrosine kinase (TK) in mice leads to exaggerated responses to injury in several murine models of inflammation as well as increased lethality in response to endotoxin (lipopolysaccharide [LPS]). Using a well-characterized model of LPS-induced acute liver failure (ALF) in galactosamine (GalN)-sensitized mice, we show that Ron TK(-/-) mice display marked protection compared with control Ron TK(+/+) mice. Whereas control mice have profound elevation of serum aminotransferase levels (a marker of hepatocyte injury) and hemorrhagic necrosis of the liver, in dramatic contrast, Ron TK(-/-) mice have mild elevation of aminotransferase levels and relatively normal liver histology. These findings are associated with a reduction in the number of liver cells undergoing apoptosis in Ron TK(-/-) mice. Paradoxically, treatment of Ron TK(-/-) mice with LPS/GalN leads to markedly elevated (3.5-fold) serum levels of tumor necrosis factor (TNF) alpha, a key inflammatory mediator in this liver injury model, as well as reduced amounts of interleukin (IL) 10 (a suppressor of TNF-alpha production) and interferon (IFN)-gamma (a TNF-alpha sensitizer). These results show that ablation of the TK activity of the Ron receptor leads to protection from the development of hepatocellular apoptosis in response to treatment with LPS/GalN, even in the presence of excessive levels of serum TNF-alpha. In conclusion, our studies show that the Ron receptor TK plays a critical role in modulating the response of the liver to endotoxin.     

Inducible histamine protects mice from P. acnes-primed and LPS-induced hepatitis through H2-receptor stimulation

BACKGROUND & AIMS: Inducible histamine and histamine H2-receptors have been suggested to be involved in innate immune response. METHODS: We examined a functional role of inducible histamine in the protection against hepatic injury and lethality in Propionibacterium acnes -primed and lipopolysaccharide-induced hepatitis, using histidine decarboxylase knockout and H2-receptor knockout mice. RESULTS: Lipopolysaccharide challenge after Propionibacterium acnes priming increased histidine decarboxylase activity in the liver of wild-type mice, associated with a marked elevation of histamine turnover. Histidine decarboxylase-like immunoreactivity was observed in CD68-positive Kupffer cells/macrophages. Treatment of wild-type mice with famotidine or ranitidine but not d -chlorpheniramine augmented hepatic injury and inhibited the survival rate significantly. The same dose of Propionibacterium acnes and lipopolysaccharide induced severe hepatitis and high lethality in histidine decarboxylase knockout and H2-receptor knockout mice; the former were rescued by the subcutaneous injection of histamine. Immunohistochemical study supported the protective role of histamine against the apoptosis of hepatocytes. Histamine suppressed the expression of IL-18 and tumor necrosis factor alpha in the liver, leading to the reduced plasma levels of cytokines including IL-18, TNF-alpha, IL-12, IFN-gamma, and IL-6. CONCLUSIONS: These findings as a whole indicated that endogenously produced histamine in Kupffer cells/macrophages plays a very important role in preventing excessive innate immune response in endotoxin-induced fulminant hepatitis through the stimulation of H2-receptors.     

Mannose-conjugated alendronate selectively depletes Kupffer cells and inhibits endotoxemic shock in the mice.

To elucidate the roles of Kupffer cells in the host-defense mechanisms and liver injury, we synthesized a mannose-conjugated alendronate (MANA) and examined its effects on Kupffer cells and lipopolysaccharide (LPS)-induced liver injury in the mice. Intravenous administration of a small amount of MANA (50mumol/kg) rapidly and selectively depleted Kupffer cells in the mice. The depletion of Kupffer cells by MANA resulted in a marked decrease of the production of both TNF-alpha and IL-1beta in the plasma during the liver injury induced by low (1mg/kg) and lethal (75mg/kg) doses of LPS. The effect was so remarkable that all animals treated with a lethal dose of LPS survived without any sign of endotoxemia. These findings indicate that Kupffer cells play critical roles in the development of endotoxemia, and that MANA will be useful in studies to elucidate pathophysiological roles of Kupffer cells in various liver diseases.     

Effects of free radical scavenger on acute liver injury induced by d-galactosamine and lipopolysaccharide in rats.

Aim: Acute severe liver injury still has a high mortality rate. Acute liver injury induced by a coadministration of d-galactosamine (GalN) and lipopolysaccharide (LPS) is an experimental model of fulminant hepatitis in rats. Our aim is to investigate the effects of free radical scavenger on the injury induced by GalN/LPS in rats. Methods: Free radical scavenger edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) was twice injected into rats 5 min before and 60 min after the GalN/LPS injection. Liver injury was biochemically and histologically assessed. The survival rate was examined 72 h after the intoxication. Results: In the GalN/LPS-treated rats, a marked elevation in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels was observed. On the other hand, edaravone significantly inhibited the elevation in serum AST and ALT levels. The efficacy of edaravone was also confirmedby histological analysis. Edaravone lowered the levels of proinflammatory cytokines TNF-alpha mRNA and interleukin-6 mRNA expression, antioxidative enzyme heme oxygenase-1 protein and myeloperoxidase activity, a marker of neutrophil infiltration, in rat livers. In addition, edaravone reduced the mortality rate in GalN/LPS-treated rats as compared to the rats without edaravone treatment. Conclusions: Free radical scavenger edaravone effectively ameliorated the liver injury induced by the GalN/LPS administration in rats, not only by attenuating oxidative stress, but also by reducing the expression of proinflammatory cytokines.     

Differential effects of pyrrolidine dithiocarbamate on TNF-alpha-mediated liver injury in two different models of fulminant hepatitis

BACKGROUND/AIMS: Pyrrolidine dithiocarbamate (PDTC) is an inhibitor of nuclear factor kappa B (NF-kappaB) activation. The present study aimed to investigate the effects of PDTC on lipopolysaccharide (LPS)-induced liver injury in two different models of fulminant hepatitis. METHODS: Mice infected with Bacillus Calmette Guerin (BCG) were challenged with LPS (0.2 mg/kg) to induce the model of inflammatory liver injury. Mice were injected with D-galactosamine (GalN, 600 mg/kg) and LPS (20 microg/kg) to induce the model of apoptotic liver injury. In the treatment groups, mice were pre-treated with PDTC (100 mg/kg), initiated 24 h prior to LPS. RESULTS: PDTC pretreatment reduced the infiltration of inflammatory cells, inhibited NF-kappaB activation and the expression of tumor necrosis factor alpha (TNF-alpha), attenuated nitric oxide production, and alleviated hepatic glutathione depletion. Correspondingly, PDTC reduced serum alanine aminotransferase, improved hepatic necrosis, and prolonged the survival in the BCG/LPS model. Conversely, PDTC accelerated death and aggravated liver apoptosis in the GalN/LPS model, although it reduced nitric oxide production, attenuated glutathione depletion, and inhibited the expression of TNF-alpha in liver. CONCLUSIONS: PDTC protects mice against BCG/LPS-induced inflammatory liver injury through the repression of NF-kappaB-mediated TNF-alpha release, while it seems to be detrimental in GalN/LPS-induced apoptotic liver damage.     

Etoposide prevents apoptosis in mouse liver with D-galactosamine/lipopolysaccharide-induced fulminant hepatic failure resulting in reduction of lethality

D-Galactosamine (GalN)/lipopolysaccharide (LPS)-induced liver injury is an experimental model of fulminant hepatic failure in which tumor necrosis factor alpha (TNF-alpha) plays a pivotal role. We examined the effects of etoposide on GalN/LPS-induced fulminant hepatic failure. Mice were given an intraperitoneal dose of GalN (800 microg/g body weight)/LPS (100 ng/g body weight) with and without intraperitoneal etoposide (10 microg/g body weight) treatment. Liver injury was assessed biochemically and histologically. TNF-alpha levels in the serum, and apoptosis of hepatocytes and CPP32/caspase-3 in the liver, were determined. GalN/LPS treatment caused lethal liver injury in 87% of animals (13 of 15). The effect was associated with significant increases in TNF-alpha and alanine transaminase (ALT) levels in serum, the number of apoptotic hepatocytes, CPP32/caspase-3 activity, and TNF receptor 1 (TNFR1) mRNA expression in the liver. Etoposide (10 microg/g body weight) was given 3 times (at 50, 26, and 4 hours before GalN/LPS administration). Treatment of GalN/LPS-treated mice with etoposide reduced apoptosis of hepatocytes, resulting in reduction of lethality (13% [2 of 15]), while another topoisomerase II inhibitor, IRCF-193, showed no significant effect. The antilethal effect of etoposide was also confirmed in GalN/TNF-alpha-induced fulminant hepatic failure. Etoposide treatment reduced CPP32/caspase-3 activity in the liver, although it did not alter the serum TNF-alpha levels or hepatic TNFR1 mRNA expressions. In addition, etoposide treatment enhanced the mRNA and protein expression of Bcl-xL, an antiapoptotic molecule in the liver. The present findings suggest that etoposide prevents endotoxin-induced lethal liver injury by up-regulation of Bcl-xL, and that etoposide could be useful for the treatment of TNF-alpha-mediated liver diseases.     

Eosinophil-induced liver injury: an experimental model using IL-5 transgenic mice

BACKGROUND/AIMS: In certain liver diseases, activated eosinophils are considered to be important effector cells in addition to T-cell-mediated cytotoxicity. No experimental model, however, has been developed for in vivo analysis of the cytotoxic mechanisms. METHODS: Interleukin-5 (IL-5) transgenic mice (C3H/HeN-TgN(IL-5)Imeg), which exhibit marked eosinophilia without liver injury, were injected once with 25 microg of lipopolysaccharide (LPS) intraperitoneally. The mice were sacrificed weekly and eosinophilic injuries were assessed microscopically. To clarify the role of Kupffer cells and tumor necrosis factor-alpha (TNF-alpha) in the liver injury, gadolinium chloride (GdCl3) and anti-TNF-alpha neutralizing antibody were administrated before the LPS injection. RESULTS: Two weeks after injection, transgenic mice exhibited marked infiltration of eosinophils and extensive lobular necrosis. Transmigration of eosinophils through vascular endothelium and degranulation of eosinophil cytotoxic granules in inflamed areas were observed. These eosinophilic injuries were transient, but liver-specific. Pre-administration of GdCl3 and anti-TNF-alpha markedly reduced the hepatic inflammation, suggesting that LPS-activated Kupffer cells play a key role in producing the cytotoxicity of eosinophils by releasing TNF-alpha. CONCLUSIONS: We have established an experimental model of eosinophil-induced liver injury using IL-5 transgenic mice. Since this model is simple and highly reproducible, it will be useful for analysis of in vivo cytotoxic mechanisms of eosinophils.     

TLR4 mediates LPS-induced HO-1 expression in mouse liver： Role of TNF-α and IL-lβ

AIM: Heme oxygenase (HO)-I catalyzes the conversion of heme to biliverdin, iron and carbon monoxide. HO-1 is induced by many stimuli including heme, Hb, heat stress,lipopolysaccharide (LP5) and cytokines. Previous studies demonstrated that LP5 induced HO-1 gene activation and HO-1 expression in liver. However, the mechanisms of LPS-induced HO-1 expression in liver remain unknown. The effect of toll-like receptor-4 (TLR4) on LPS-induced liver HO-1 expression and the role of TNF-α and IL-1β in this condition were determined.METHODS: HO-1 expression was determined by immunofluorescent staining and immunoblotting. Double immunofluorescent staining was performed to determine the cell type of HO-1 expression in liver.RESULTS: A low dose of LPS significantly increased HO-1 expression in the liver which was localized in Kupffer cells only. Furthermore, HO-1 expression was enhanced by three doses of LPS. HO-1 expression was significantly inhibited in the liver of TLR4 mutant mice. While the liver HO-1 expression in TNF KO mice was much lower than that in C57 mice following the same LPS treatment, IL-1β KO had a slight influence on liver HO-1 expression following LPS treatment.CONCLUSION: The preserfl: results confirm that macrophages are the major source of HO-1 in the liver induced by LPS.This study demonstrates that TLR4 plays a dominant role in mediating HO-1 expression following LPS. LPS-induced HO-1 expression is mainly mediated by endogenous TNF-α, but only partially by endogenous IL-1β.     

Kupffer cells modulate splenic interleukin-10 production in endotoxin-induced liver injury after partial hepatectomy

BACKGROUND/AIMS: This study was conducted to investigate the implication of Kupffer cells and the spleen in interleukin (IL)-10 production in endotoxin-induced liver injury after hepatectomy. METHODS: Rats were divided into five groups: the S group, sham-operation; the SG group, sham-operation followed by intravenous gadolinium chloride (GdCl(3): 7 mg/kg) administration to inhibit Kupffer cell function; the H group, two-thirds hepatectomy; the HG group, hepatectomy and subsequent GdCl(3) administration; the HGS group, hepatectomy and splenectomy with GdCl(3) administration. Lipopolysaccharide (1.5 mg/kg) was intravenously administered for each group 48 h after surgery. RESULTS: GdCl(3) treatment significantly suppressed the elevation of plasma tumor necrosis factor (TNF)-alpha levels by lipopolysaccharide administration with completely inhibited induction of hepatic TNF-alpha and IL-10 mRNAs. In the HG group, marked increase in plasma IL-10 levels associated with enhanced splenic IL-10 mRNA was observed 1 h after lipopolysaccharide administration when compared to those in the H and HGS groups. Plasma TNF-alpha/IL-10 ratio 1 h after lipopolysaccharide administration was higher in the order of H, HGS and HG groups. Hepatic parenchymal damage and the 24-h mortality were lowest in group HG, followed by groups HGS and H. CONCLUSIONS: Kupffer cells after hepatectomy may aggravate endotoxin-induced liver injury via down-regulation of IL-10 production in the spleen.     

Staphylococcal enterotoxin B induces hepatic injury and lethal shock in endotoxin-resistant C3H/HeJ mice despite a deficient macrophage response

Bacterial toxins, including endotoxin/LPS as well as superantigens, are major causative agents of multi-organ failure associated with sepsis and liver disease. However, the precise mechanisms initiating cell activation by the toxins have not been clarified. We compared lethal shock and cytokine production in response to LPS with responses to the superantigen staphylococcal enterotoxin B (SEB) in both LPS-responsive C3H/HeN mice and LPS-hyporesponsive C3H/HeJ mice treated with D-galactosamine (GalN). LPS was not lethal and did not induce production of TNF-alpha in C3H/HeJ mice. In contrast, SEB produced lethal shock associated with liver failure and induced cytokines such as TNF-alpha, IFN-gamma, and IL-2 in both C3H/HeN and C3H/HeJ mice. Peritoneal macrophages from C3H/HeJ mice did not produce TNF-alpha in vitro in response to SEB or LPS. However, no significant difference was observed in production of TNF-alpha in response to stimulation in vitro by SEB between C3H/HeN and C3H/HeJ splenic lymphocytes. We have demonstrated that SEB causes lethal toxicity associated with liver injury in LPS-hyporesponsive C3H/HeJ mice and that as the underlying mechanism, the normal T-cell function in these mice still maintained the sensitivity to SEB since the genetic defect of C3H/HeJ mice unresponsive to LPS and SEB is restricted in macrophages/monocytes and does not extend to T cells.