Fas/FasL play a central role in pancreatitis-induced hepatocyte apoptosis

Progress in research of liver injury induced by acute biliary pancreatitis

Acute biliary pancreatitis (ABP) not only causes acute inflammation of the pancreas, but also leads to obstruction or infection of the biliary system. Liver injury is one of the most common complications of ABP. The pathological mechanisms mainly include infection and endotoxin, cholestasis, pancreatic enzyme damage, microcirculatory disorders, and oxidative stress, and the research conclusions are mostly derived from animal experiments. On the basis of routine medical treatment of ABP, active anti-infective treatment and rapid relief of biliary obstruction can promote the recovery of ABP-related liver injury.

Effect of JAK2/STAT3 signaling pathway on liver injury associated with severe acute pancreatitis in rats

Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling constitutes one of the major pathways for cytokine signal transduction. However, the role of the JAK2/STAT3 pathway in liver injury during severe acute pancreatitis (SAP) remains unclear. The aim of this study was to investigate the role of the JAK2/STAT3 signaling pathway in liver injury after SAP. In the present study 64 male Sprague-Dawley rats were randomly divided into four groups: Control, AG490 (inhibition of JAK2), SAP and SAP with AG490. SAP was induced by retrograde infusion of 4% sodium taurocholate into the biliopancreatic duct. The activities of amylase (AMY) and liver enzymes were measured in serum. Livers and pancreas were isolated for measurements of histological damage. Blood and liver samples were taken for the measurement of TNF-α, IL-6 and IL-18 concentrations. The expression levels of JAK2 and STAT3 in liver tissue were detected by immunohistochemical staining and western blotting. The results demonstrated that amylase and liver enzymes were higher in the SAP groups compared with the control, AG490 and AG490-treated groups. The serum levels of TNF-α, IL-6 and IL-18 were effectively increased in the SAP groups, whereas they were reduced by AG490. Interestingly, JAK2 and STAT3 protein expression levels were significantly increased following induction of SAP and were significantly decreased in the AG490-pretreated groups. Administration of AG490 decreased the activity of pro-inflammatory cytokines and significantly attenuated SAP associated-liver injury in the rats. These results suggested that the mechanism may relate to the inhibition of TNF-α, IL-6 and IL-18, and inhibiting excessive JAK2 and STAT3 activation, and may play a crucial role in the liver injury associated with SAP.

Dynamic Changes of Soluble Fas and IL-2/IL-10 in serum and Fas Expression in Lung in the Rats of Acute Necrotizing Pancreatitis

BACKGROUND

To investigate the dynamic changes of serum IL-2, IL-10, sFas and IL-2/IL-10 in a rat model with acute necrotizing pancreatitis (ANP). To explore the role of Th1/Th2 polarization and the Fas expression in the lung of rats with ANP.

METHODS

A total of 64 Sprague-Dawley rats were randomly divided into normal control group and ANP model group. ANP models were induced by injection of 50 g/L sodium taurocholate (4 mL/kg) under the pancreatic membrane. In the normal control group, the rats received isovolumetric injection of 9 g/L normal saline solution. The blood samples in each group were obtained via superior mesenteric vein for measuring IL-2, IL-10 and soluble Fas. The levels of IL-2, IL-10 and soluble Fas were determined by ELISA. The severity of lung injury was evaluated by pathologic score. The expression of Fas in lung was measured by immunohistochemistry.

RESULTS

In the ANP model group, levels of serum IL-2 were significantly higher than those of control group (P < 0.01), and peaked at 6 hours; levels of serum IL-10 were significantly higher than those of control group at 6 and 12 hours (P < 0.01); the ratios of IL-2/IL-10 were significantly higher than those of control group at 0.5 hours and 2 hours, however, they were significantly lower than those of control group at 6 hours, (P < 0.01), and returned to the normal level (P > 0.05). In Fas/APO-1 assay, there was no significant difference between the two groups. The pathological changes were aggravated significantly in model group compared with the control group. Immunohistochemistry stain showed Fas expression was absent in normal pulmonary tissue, whereas in pulmonary tissue Fas expression gradually increased 0.5 hours after induction of pancreatitis, and reached their peaks at 12 hours.

CONCLUSIONS

Fas are involved in the pathogenesis of pancreatitis associated lung injury, the mechanism might be related to the Fas mediated T helper cell apoptosis.

Advances in the relationship between macrophage and acute pancreatitis

Acute pancreatitis (AP) has seriously endangered the life and health of human beings, and it is often accompanied with systemic inflammatory response syndrome (SIRS), serious infections, septic shock and multiple organ dysfunction syndrome, which lead to death of patients. With the deep study on the pathogenesis of AP mechanism, it is demonstrated that macrophages play an important role in antigen presentation-activated immune responses of AP patients. This paper reviews the progress in the relationship between macrophages and acute pancreatitis.

Role of Kupffer cells in the induction of tolerance of orthotopic liver transplantation in rats

Because the role of Kupffer cells (KCs) in liver transplantation (LT) tolerance is not well understood, we investigated their role in liver allograft acceptance in rats. Male Sprague-Dawley rats were randomly assigned to either an LT group or a transplantation group pretreated with GdCl(3) (Gd group). The rats were postoperatively sacrificed at indicated times for histology and assessment of KC function, nuclear factor kappa B (NF-kappaB) activity, and cytokine production. KCs and T cells (TCs) were isolated from allografts to assess Fas/Fas ligand (FasL) expression. Cytotoxicity of KCs against TCs was monitored by coculturing of (3)H-thymidine TCs with KCs at various effector-to-target ratios. The results were as follows. First, grafts were spontaneously accepted in the LT group with evident apoptosis of TCs; however, inhibition of KCs by pretreatment with GdCl(3) decreased TC apoptosis and shortened the survival of allografts. Second, KCs in the LT group had increased levels of FasL messenger RNA and protein with respect to that in the Gd group. Third, by in vitro cocultivation assays, KCs induced TC apoptosis though elevated expression of FasL, and this process could be blocked by anti-FasL antibody. Fourth, there was a positive correlation between activation of NF-kappaB and FasL expression in KCs and interleukin-4 production in the LT group, and the activation of NF-kappaB was inhibited by pretreatment with GdCl(3). In conclusion, KC-induced depletion of TCs via the Fas/FasL pathway might play a critical role in LT tolerance. However, the tolerance is abrogated by suppression of FasL and IL-4 expression via inhibition of NF-kappaB activity by GdCl(3).

Role of Fas/FasL in acute pancreatitis-associated liver injury

Fas/FasL-mediated apoptosis is involved acute pancreatitis-associated liver injury. It up-regulates proapoptotic pathways in the liver and promotes hepatocytic injury as well as hepatocytic apoptosis during acute pancreatitis. The signal of the production of FasL and the expression of FasL were up-regulated in kupffer cells during acute pancreatitis. Then, FasL activates Fas-associated death domain (FADD) and unmasks its death effector domain (DED) followed by subsequent activation of the Caspase cascade and downstream effector Caspases, ultimately resulting in DNA cleavage and hepatocytic apoptosis. This review aimed to elucidate the construction, distribution and function of Fas/FasL, and to highlight mechanism of acute pancreatitis-associated liver injury mediated by Fas/FasL.

Deletion of toll-like receptor-4 downregulates protein kinase C-zeta and attenuates liver injury in experimental pancreatitis

BACKGROUND

Toll-like receptor-4 (TLR4) and protein kinase C-zeta (PKC-zeta) play a role in macrophage activation. We hypothesized that deletion of TLR4 downregulates PKC-zeta and attenuates liver cell apoptosis in experimental pancreatitis.

METHODS

Acute pancreatitis was induced by choline-deficient ethionine diet in C57/BL6 (TLR4+/+ and TLR4-/-) mice.

RESULTS

During pancreatitis, staining for TLR4 and PKC-zeta, which colocalized in Kupffer cells but not in hepatocytes, increased in TLR4+/+ mice and decreased in TLR4-/- mice. In TLR4+/+ mice, pancreatitis increased TLR4 protein and mRNA and PKC-zeta protein and activity, nuclear factor (NF)-kappaB, ERK1/2, caspase-3 cleavage, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining; all P < .01 versus controls. In TLR4-/- mice with pancreatitis, PKC-zeta mRNA and activity were reduced, ERK1/2 and caspase-3 did not increase, and NF-kappaB and TUNEL (mostly in hepatocytes) increased mildly (all P < .01 vs control). PKC-zeta did not interact directly with NF-kappaB; however, during pancreatitis, coimmunoprecipitation of PKC-zeta with ERK1/2 was increased in TLR4+/+ mice and was attenuated in TLR4-/- mice (all P < .01 vs control), indicating that PKC-zeta interacts with ERK1/2.

CONCLUSION

Acute pancreatitis upregulates TLR4, PKC-zeta, NF-kappaB, and ERK1/2, and increases apoptosis in mice livers. PKC-zeta induces nuclear translocation of NF-kappaB via ERK1/2-dependent mechanisms. Deletion of TLR4 downregulates PKC-zeta, NF-kappaB, and ERK1/2, and attenuates pancreatitis-induced liver cell apoptosis.

Dynamic changes of IL-2/IL-10, sFas and expression of Fas in intestinal mucosa in rats with acute necrotizing pancreatitis

AIM: To investigate dynamic changes of serum IL-2, IL-10, IL-2/IL-10 and sFas in rats with acute necrotizing pancreatitis. To explore the expression of Fas in intestinal mucosa of rats with acute necrotizing pancreatitis (ANP).

METHODS: A total of 64 Sprague-Dawley (SD) rats were randomly divided into two groups: normal control group (C group), ANP group (P group). An ANP model was induced by injection of 50 g/L sodium taurocholate under the pancreatic membrane. Normal control group received isovolumetric injection of 9 g/L physiological saline solution using the same method. The blood samples of the rats in each group were obtained via superior mesenteric vein to measure levels of IL-2, IL-10, sFas and calculate the value of IL-2/IL-10. The levels of IL-2, IL-10 and sFas were determined by ELISA. The severity of intestinal mucosal injury was evaluated by pathologic score. The expression of Fas in intestinal mucosal tissue was determined by immunohistochemistry staining.

RESULTS: Levels of serum IL-2 were significantly higher in P group than those of C group (2.79 ± 0.51 vs 3.53 ± 0.62, 2.93 ± 0.89 vs 4.35 ± 1.11, 4.81 ± 1.23 vs 6.94 ± 1.55 and 3.41 ± 0.72 vs 4.80 ± 1.10, respectively, P < 0.01, for all) and its reached peak at 6 h. Levels of serum IL-10 were significantly higher in P group than those of C group at 6 h and 12 h (54.61 ± 15.81 vs 47.34 ± 14.62, 141.15 ± 40.21 vs 156.12 ± 43.10, 89.18 ± 32.52 vs 494.98 ± 11.23 and 77.15 ± 22.60 vs 93.28 ± 25.81, respectively, P < 0.01, for all). The values of IL-2/IL-10 were higher significantly in P group than those of C group at 0.5 h and 2 h (0.05 ± 0.01 vs 0.07 ± 0.02 and 0.02 ± 0.01 vs 0.03 ± 0.01, respectively, P < 0.01, for all), and it were significantly lower than those of C group at 6 h (0.05 ± 0.02 vs 0.01 ± 0.01, P < 0.01) and returned to the control level at 12 h (0.04 ± 0.01 vs 0.05 ± 0.02, P > 0.05). In sFas assay, there was no significant difference between P group and C group (3.16 ± 0.75 vs 3.31 ± 0.80, 4.05 ± 1.08 vs 4.32 ± 1.11, 5.93 ± 1.52 vs 5.41 ± 1.47 and 4.62 ± 1.23 vs 4.44 ± 1.16, respectively, P > 0.05, for all). Comparison of P group and C group, the pathological changes were aggravated significantly in P group. Immunohistochemistry staining show the expression of Fas was absent in normal intestinal tissues, however, it gradually increased after induction of pancreatitis in intestinal tissue, then reached their peaks at 12 h.

CONCLUSION: Fas were involved in the pathogenesis of pancreatitis associated intestinal injury. The mechanisms of Fas may be associated to Fas mediated T helper cell apoptosis.

Pathogenesis and treatment of acute pancreatitis with liver injury

Acute pancreatitis is a frequent acute abdomen in clinic, causes damages not only to pancreas, but also to distant organs. Liver is one of the mainly involved organs. The development of liver injury may aggravate pancreatitis. The pathogenesis of acute pancreatitis with liver injury is mainly related to cytokines, pancreatic enzyme, oxidative stress, microcirculation disturbance, apoptosis and pancreatitis-associated ascitic fluid, etc. Its treatment is also to eradicate these factors. However, more methods are still under animal studies. Their clinical application requires further study.

Protein kinase C-zeta (PKC-zeta) regulates Kupffer cell apoptosis during experimental sepsis

BACKGROUND

Kupffer cells play an important role in sepsis-mediated liver injury. We tested the hypothesis that PKC-zeta plays a critical role in Kupffer cell apoptosis during sepsis.

METHODS

Sepsis was induced in rats by cecal ligation and puncture (CLP); 12 h later, livers were assayed for PKC-zeta, IKKalpha, IKKbeta, IKKgamma, NF-kappaB, Fas/FasL, Caspase-3, and DNA fragmentation. Kupffer cells from control rats were infected with AdPKC-zeta DN to inhibit PKC-zeta, or transfected with pCMVPKC-zeta to overexpress PKC-zeta, and then treated with lipopolysaccharide (LPS). Cellular extracts were assayed for PKC-zeta, IKKalpha, IKKbeta, IKKgamma, NF-kappaB, Fas/FasL, Caspase-3, and DNA fragmentation.

RESULTS

During sepsis, PKC-zeta localized in cells positive for the macrophage marker (F4/80). CLP upregulated PKC-zeta protein and activity, IKKbeta, IKKgamma, NF-kappaB, Fas/FasL, Caspase-3, and increased DNA fragmentation in rat livers (all p<0.001). AdPKC-zeta DN attenuated the LPS-induced upregulation of PKC-zeta activity, IKKbeta, IKKgamma, NF-kappaB, Fas/FasL, Caspase-3, and DNA fragmentation in Kupffer cells (all p<0.001), whereas overexpression of PKC-zeta augmented LPS-induced upregulation of IKKbeta, IKKgamma, NF-kappaB, Caspase-3, and DNA fragmentation (p<0.001).

CONCLUSION

PKC-zeta plays an important role in sepsis-induced apoptosis of Kupffer cells via activation of NF-kappaB and Fas/FasL. Manipulating the response of Kupffer cells to cellular stress may have important therapeutic implications.

Protein kinase C-zeta is critical in pancreatitis-induced apoptosis of Kupffer cells

Protein kinase C-zeta (PKC-zeta) regulates cell death via NF-kappaB; therefore, we tested the hypothesis that PKC-zeta plays a critical role in pancreatitis-induced Kupffer cell apoptosis. Acute pancreatitis was induced in rats by cerulein injection 24 h later, livers were assayed for PKC-zeta, IKKalpha, IKKbeta, IKKgamma, NF-kappaB, Fas/FasL, and apoptosis was assessed with Caspase-3 and DNA fragmentation. Kupffer cells from unoperated rats were infected with a PKC-zeta domain-negative adenovirus (AdPKCzeta-DN) to inhibit PKC-zeta, or transfected with pCMVPKC-zeta to overexpress PKC-zeta, and then stimulated with pancreatic elastase; cellular extracts were assayed for PKC-zeta, IKKalpha, IKKbeta, IKKgamma, NF-kappaB, Fas/FasL, Caspase-3, and DNA fragmentation. Cerulein-induced pancreatitis upregulated PKC-zeta protein and activity, IKKbeta, IKKgamma, NF-kappaB, Fas/FasL, Caspase-3 and increased DNA fragmentation in rat livers (all p < 0.001 vs control). AdPKCzeta-DN abolished elastase-induced upregulation of PKC-zeta activity, IKKbeta, IKKgamma, NF-kappaB, Fas/FasL, Caspase-3 and DNA fragmentation (all p < 0.001 vs infection control), whereas overexpression of PKC-zeta augmented elastase-induced upregulation of IKKbeta, IKKgamma, Fas/FasL, Caspase-3 and DNA fragmentation (p < 0.001 vs control). PKC-zeta plays a critical role in pancreatitis-induced Kupffer cell apoptosis via NF-kappaB and Fas/FasL. The ability of Kupffer cells to autoregulate their stress response by upregulating their death receptor/ligand and key proapoptotic cell signaling systems warrants further investigation.

Therapeutic treatment with poly(ADP-ribose) polymerase inhibitors attenuates the severity of acute pancreatitis and associated liver and lung injury

BACKGROUND AND PURPOSE

The mortality associated with acute pancreatitis (AP) is largely attributable to abnormalities that occur in distant organs and supportive care remains the only treatment for patients with these complications. Recently, prophylactic pharmacological blockade of poly(ADP-ribose) polymerase (PARP) enzymes has been shown to attenuate the severity of the disease. However, the clinical relevance of PARP inhibitors administered after the onset of AP remains uncertain. The aim of the present study was to investigate the therapeutic effects of PARP inhibitors in established AP.

EXPERIMENTAL APPROACH

Mice were fed a choline/methionine-deficient/ethionine-supplemented (CMDE) diet to induce AP. PARP inhibitors were given at 36 h after the onset of CMDE diet. Severity of pancreatitis was assessed by measurements of serum amylase, lipase, IL-1beta and IL-6, and histological grading. Serum hepatic enzymes, myeloperoxidase (MPO) activity and morphological changes were measured as indicators of hepatic insult. Lung injury was evaluated by MPO activity and morphological changes. Survival rates of mice were monitored for 7 days.

KEY RESULTS

CMDE diet administration resulted in a significant increase in serum amylase, lipase, IL-1beta, IL-6, alanine aminotransferase and aspartate aminotranferase levels, indicating AP and associated liver injury. Analysis of the histopathological changes in pancreas, liver and lung revealed extensive tissue damage. Treatment of mice with PARP-inhibitors after the onset of AP was associated with a reduction in the severity of AP and, accordingly, with a reduced mortality rate.

CONCLUSIONS AND IMPLICATIONS

Our results support the therapeutic application of PARP inhibitors in the treatment of established AP.

Suppressive effect of herbal medicine saikokeishito on acinar cell apoptosis in rat spontaneous chronic pancreatitis

BACKGROUND/AIMS

Chronic pancreatitis is characterized by acinar destruction and fibrosis. We previously reported that apoptosis is involved in acinar destruction in chronic pancreatitis in the WBN/Kob rat. This study aimed to elucidate the antiapoptotic effect of Saikokeishito (TJ-10).

METHODS

Four-week-old male WBN/Kob rats were fed a special pellet diet (MB-3) with or without TJ-10 (80 mg/100 g body weight) for 20 weeks. Pancreas was histopathologically examined every 4 weeks, and the expression of apoptosis-related factors such as Fas and Fas ligand (FasL) mRNA and protein was analyzed with RT-PCR, in situ hybridization and immunohistochemistry. Apoptosis was detected with a TUNEL method.

RESULTS

In untreated WBN/Kob rats, chronic pancreatitis developed at 12 weeks and progressed with marked acinar cell destruction at 16 weeks. The expression of Fas and FasL peaked at 12 and 20 weeks. An apoptotic index in acinar cells correlated to the expression of Fas and FasL mRNA. However, in the TJ-10-treated rats, the rate of pancreatic acinar cell destruction, the apoptotic index at 12-20 weeks, and the expression of Fas and FasL at 12 and 20 weeks decreased significantly compared to those in untreated rats.

CONCLUSION

These results suggest that TJ-10 has a therapeutic effect on chronic pancreatitis by the suppression of acinar cell apoptosis via the Fas/FasL system.

A dual altered peptide ligand down-regulates myasthenogenic T cell responses and reverses experimental autoimmune myasthenia gravis via up-regulation of Fas-FasL-mediated apoptosis

Myasthenia gravis (MG) and experimental autoimmune MG (EAMG) are T cell-dependent, antibody-mediated autoimmune diseases. A dual altered peptide ligand (APL) that is composed of the tandemly arranged two single amino acid analogues of two myasthenogenic peptides, p195-212 and p259-271, was demonstrated to down-regulate in vitro and in vivo MG-associated autoreactive responses. The aims of this study were to investigate the possible role of Fas-FasL-mediated apoptosis in the down-regulatory mechanism of the dual APL. We demonstrate here the effect of the dual APL on expression of key molecules involved in the Fas-FasL pathway, in a p195-212-specific T cell line, in mice immunized with Torpedo acetylcholine receptor and in mice afflicted with EAMG (induced with the latter). In vitro and in vivo results show that the dual APL up-regulated expression of Fas and FasL on the CD4 cells. Expression of the pro-apoptotic molecules, caspase 8 and caspase 3, was significantly up-regulated, while anti-apoptotic cFLIP and Bcl-2 were down-regulated upon treatment with the dual APL. The dual APL also increased phosphorylation of the mitogen-activated protein kinases, c-Jun-NH2-terminal kinase and p-38, known to play a role in the regulation of FasL expression. Further, in the T cell line incubated with the dual APL as well as in mice of the SJL inbred strain immunized with the myasthenogenic peptide and treated concomitantly with the dual APL, the percentage of apoptotic cells increased. Results strongly indicate that up-regulation of apoptosis via the Fas-FasL pathway is one of the mechanisms by which the dual APL reverses EAMG manifestations in C57BL/6 mice.

Diminished response to interleukin-10 and reduced antibody-dependent cellular cytotoxicity of cord blood monocyte-derived macrophages

Monocyte-derived macrophage (MPhi) subsets are generated by antagonistic induction pathways. A helper MPhi-type (Mh-MPhi) is induced by interferon gamma (IFN-gamma), whereas a cytotoxic MPhi-type (Mc-MPhi), induced by interleukin-10 (IL-10), is a potent mediator of antibody-dependent cellular cytotoxicity (ADCC). Compared with MPhi from healthy adults [peripheral blood monocyte-derived macrophages (PBMPhi)], cord blood MPhi (CBMPhi) were found less capable of generating Mh-MPhi. Here we tested the hypothesis that their generation of Mc-MPhi via IL-10 is also impaired. MPhi surface markers were phenotyped. IL-10 protein and mRNA production were detected after stimulation [alphaCD3 monoclonal antibody (mAb)]. CBMPhi or PBMPhi were co-cultured with MPhi-depleted mononuclear cells of adults and CD4-targeting antibodies as models for ADCC were added. In cord blood, we found diminished alphaCD3-induced IL-10 protein and mRNA production (p < 0.05 versus adults). Basal CD16 and HLA-DR expressions on CBMPhi of preterm and full-term neonates were lower (p < 0.05 versus PBMPhi). IL-10 had reduced effects on CD16 up- and HLA-DR down-modulation on CBMPhi (p < 0.05 versus PBMPhi). CD4-directed receptor modulation and deletion were reduced in the presence of CBMPhi (p < 0.05 versus PBMPhi). IL-10 failed to enhance their ADCC capacity, which was in contrast to PBMPhi (p < 0.05). These data suggest that CBMPhi have an impaired cytotoxic capacity via lower sensitivity toward IL-10.

Pancreatic response to endotoxin after chronic alcohol exposure: switch from apoptosis to necrosis?

Chronic alcohol consumption is known to increase the susceptibility to acute and chronic pancreatitis, and it is likely that a cofactor is required to initiate the progression to alcoholic pancreatitis. The severity and complications of alcoholic and nonalcoholic acute pancreatitis may be influenced by a number of cofactors, including endotoxemia. To explore the effect of a possible cofactor, we used endotoxin [lipopolysaccharide (LPS)] as a tool to induce cellular injury in the alcoholic pancreas. Single, increasing doses of endotoxin were injected in rats fed an alcohol or control diet and killed 24 h after the injection. We examined the mechanism by which LPS exacerbates pancreatic injury in alcohol-fed rats and whether the injury is associated with apoptosis or necrosis. We showed that chronic alcohol exposure alone inhibits apoptosis through the intrinsic pathway and the downstream apoptosis executor caspase-3 compared with the controls. Pancreatic necrosis and inflammation increased after LPS injection in control and alcohol-fed rats in a dose-dependent fashion but with a significantly greater response in the alcohol-fed animals. Caspase activities and TdT-mediated dUTP nick-end labeling positivity were lower in the alcoholic pancreas injected with LPS, whereas the histopathology and inflammation were more severe compared with the control-fed animals. Assessment of a putative indicator of necrosis, the ratio of ADP to ATP, indicated that alcohol exposure accelerates pancreatic necrosis in response to endotoxin. These findings suggest that the pancreas exposed to alcohol is more sensitive to LPS-induced damage because of increased sensitivity to necrotic cell death rather than apoptotic cell death. Similar to the liver, the pancreas is capable of responding to LPS with a more severe response in alcohol-fed animals, favoring pancreatic necrosis rather than apoptosis. We speculate that this mechanism may occur in acute alcoholic pancreatitis patients.

Nuclear factor-kappaB mediates Kupffer cell apoptosis through transcriptional activation of Fas/FasL

INTRODUCTION

Nuclear factor (NF)-kappaB is a key transcriptional factor for cell survival, inflammation, and stress response. We demonstrated that Kupffer cell-derived FasL plays a central role in pancreatitis-induced hepatocyte injury. The aim of this study was to determine the role of NF-kappaB in regulating death ligand/receptor pathway in Kupffer cells during conditions that mimic acute pancreatitis.

MATERIALS AND METHODS

Tissue cultures of rat Kupffer cells were treated with elastase (1 U/L) to mimic pancreatitis before and after infection with AdIkappaB to block activation of NF-kappaB. Tumor necrosis factor (enzyme-linked immunoassay), Fas/FasL, and caspase-3 (Western), tumor necrosis factor and Fas/FasL mRNA (reverse-transcription polymerase chain reaction), and NF-kappaB DNA binding (electrophoretic mobility shift assay) were determined. Apoptosis was measured by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) and DNA fragmentation. Gels were quantified by densitometry. Data (n=3) are mean+/-SEM; student's t test was used for statistical analysis.

RESULTS

AdIkappaB infection up-regulated mutated IkappaBalpha that maintained its binding properties to NF-kappaB. Promoter-reporter assay demonstrated that FasL gene promoter was regulated by NF-kappaB. Infection with AdIkappaB attenuated the elastase-induced up-regulation of Fas/FasL (all P<0.01 versus elastase) and NF-kappaB DNA binding but did not affect elastase-induced up-regulation of TNF. AdIkappaB attenuated elastase-induced cleavage of caspase-3, DNA fragmentation and TUNEL staining (all P<0.01 versus elastase).

CONCLUSIONS

Inhibition of NF-kappaB DNA binding down-regulates Fas/FasL and attenuates elastase-induced apoptosis; however, it has no effect on TNF production, suggesting that regulation of Fas/FasL and TNF may occur via different pathways. The ability of Kupffer cells to autoregulate their stress response by up-regulating their death ligand/receptor and apoptosis warrants further investigation.