Tauroursodeoxycholic acid alleviates hepatic ischemia reperfusion injury by suppressing the function of Kupffer cells in mice.

The aim of this study is to investigate the protective effect and the mechanism of tauroursodeoxycholic acid (TUDCA) against hepatic ischemia reperfusion (IR) injury. Male Balb/c mice were intraperitoneally injected with tauroursodeoxycholic acid (400 mg/kg) or saline solution, once per day for 3 days before surgery, and then the model of hepatic I/R injury was established. Blood and liver samples were collected from each group at 3, 6, and 24 h after surgery. Liver pathological changes, liver function, hepatocyte apoptosis and proinflammatory factors were detected. KCs were extracted, cultured and treated with TUDCA or phosphate-buffered saline (PBS) for 24 h, and then viability and phagocytosis were examined. Additionally, IRE1α/TRAF2/NF-κB pathway activity and AML cell apoptosis were detected. The results showed that TUDCA alleviated hepatic I/R injury, the level of liver function markers, and hepatocyte apoptosis in vivo. Furthermore, the proinflammatory effects of KCs were suppressed by down-regulating IRE1α/TRAF2/NF-κB pathway activity in vivo. TUDCA dose-dependently suppressed the expression of inflammatory factors and IRE1α/TRAF2/NF-κB pathway activity in vitro, consistent with the in vivo results. Therefore, TUDCA can effectively alleviate hepatic IR injury by down-regulating the activity of the IRE1α/TRAF2/NF-κB pathway to suppress the function of KCs.

Investigation for role of tissue factor and blood coagulation system in severe acute pancreatitis and associated liver injury.

This study aims to investigate the molecular mechanisms underlying the pathogenesis of severe acute pancreatitis (SAP) and SAP-associated liver injury, we performed an association analysis of the functions of tissue factor (TF) and blood coagulation system in both SAP patients and mouse SAP model. Our results showed that serum TF and tissue factor-microparticle (TF-MP) levels were highly up-regulated in both SAP patients and SAP mouse model, which was accompanied by the dysfunction of blood coagulation system. Besides, TF expression was also highly up-regulated in the Kupffer cells (KCs) of SAP mouse model. After inhibiting KCs in SAP mouse model, the amelioration of blood coagulation system functions was associated with the decrease in serum TF and TF-MPs levels, and the reduction of SAP-associated liver injury was associated with the decrease of TF expression in KCs. In conclusion, the dis-regulated TF expression and associated dysfunction of blood coagulation system are critical factors for the pathogenesis of SAP and SAP-associated liver injury. TF may serve as a potential and effective target for treating SAP and SAP-associated liver injury.

Bone marrow stromal cells attenuate LPS-induced mouse acute liver injury via the prostaglandin E 2-dependent repression of the NLRP3 inflammasome in Kupffer cells.

The nucleotide-binding and oligomerization domain-like receptor 3 (NLRP3) inflammasome participates in the pathogenesis of acute liver injury during sepsis. Bone marrow mesenchymal stem cells (BMSCs) attenuate sepsis through prostaglandin E 2 (PGE2) by increasing the interleukin-10 (IL-10) production of macrophages; moreover, NLRP3 inflammasome assembly is effectively regulated by IL-10 during infection. Whether BMSCs have an effect on the activation of the NLRP3 inflammasome and its underlying mechanism is unclear. Administering of BMSCs to mice or KCs after LPS stimulating have improved liver function and reduced activation of NLRP3 inflammasome in KCs. The beneficial effect of BMSCs was enhanced by over-expression of PGE2 and eliminated by silence of PGE2. Additionally, The IL-10 levels in the serum and supernatant were increased by given BMSCs and further increase by PGE2 over-expressed BMSCs, but decreased markedly by PGE2 silenced BMSCs. Furthermore, extracellular signal-regulated kinase 1 (ERK1) inhibitor reduced IL-10 production in KCs and blocked the inhibitory effect of PGE2 on the activation of the NLRP3 inflammasome. Our data reveal a novel mechanism of BMSC-mediated suppression of the activation of KCs through the secretion of PGE2 by BMSCs, which promotes KCs to secrete IL-10, leading to the inhibition of the NLRP3 inflammasome in KCs.

LXRα represses LPS-induced inflammatory responses by competing with IRF3 for GRIP1 in Kupffer cells.

Liver X receptors (LXRs) in the nucleus play important roles in lipid metabolism and inflammation. The mechanism of LXR regulation of the LPS-induced Toll-like receptor 4 (TLR4) inflammatory signaling pathway remains to be elucidated. C57/BL6 mice were randomly divided into four groups: control, T0901317 (a LXRs agonist), LPS and T0901317+LPS. Additionally, Kupffer cells isolated from male C57/BL6 mice were divided into the same four groups. A decreased amount of inflammatory cells infiltrated the portal areas and the hepatic sinusoids in the livers of mice in the T0901317+LPS group than in those of mice in the LPS group. In the T0901317+LPS group, the serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and tumor necrosis factor alpha (TNF-α) were lower, while the serum level of interleukin-10 (IL-10) was higher. In vitro, Kupffer cells pretreated with T0901317 for 24h presented reduced TNF-α, interferon-beta (IFN-ß) and interleukin-1 beta (IL-1ß) levels, while the IL-10 level increased; however, the mRNA and protein expression levels of interferon regulatory factor 3 (IRF3) and glucocorticoid receptor-interacting protein 1 (GRIP1) were not significantly reduced. The co-IP data illustrated that LXRα bound to GRIP1 specifically in the T0901317+LPS group, while less IRF3 was bound to GRIP1 in the T0901317+LPS group than in the LPS group. Furthermore, the DNA-binding activity of NF-κB was decreased by pretreating Kupffer cells with T0901317 for 24h. These results suggest that activated LXRα competes with IRF3 for GRIP1 binding, thus repressing IRF3 and NF-κB transcriptional activity and inhibiting the inflammatory response initiated by LPS in Kupffer cells.

Effect of taurine on IRAK4 and NF-kappa B in Kupffer cells from rat liver grafts after ischemia-reperfusion injury.

BACKGROUND: The aim of this study was to explore the protective mechanisms of taurine pretreatment against hepatic ischemia/reperfusion injury after liver transplantation. METHODS: A Sprague-Dawley-to-Sprague-Dawley rat liver transplantation model was used in this study. At 0, 60, and 180 minutes after reperfusion, expression of interleukin-1 receptor-associated kinase-4 (IRAK-4) messenger ribonucleic acid and protein in Kupffer cells was determined by real-time polymerase chain reaction and Western blotting. The activity of nuclear factor κB in Kupffer cells was determined by electrophoretic mobility shift assay. The serum tumor necrosis factor-α level was detected by enzyme-linked immunosorbent assay. Serum transaminases, liver histology, and animal survival were also investigated. RESULTS: At 60 and 180 minutes after reperfusion, levels of IRAK-4 messenger ribonucleic acid and protein, activities of nuclear factor κB, and levels of serum transaminases and tumor necrosis factor-α were all obviously elevated. However, changes in these parameters in rats treated with taurine were remarkably attenuated at the indicated time points. CONCLUSIONS: These data suggest that taurine could protect against hepatic ischemia/reperfusion injury after liver transplantation, and the protective effects may be through downregulation of IRAK-4 and downstream nuclear factor κB and tumor necrosis factor-α expression in Kupffer cells.

Prevention of common bile duct injury during laparoscopic cholecystectomy.

BACKGROUND: Since the widespread adoption of laparoscopic cholecystectomy (LC) in the late 1980s, a rise in common bile duct (CBD) injury has been reported. We analyzed the factors contributing to a record of zero CBD injuries in 10 000 consecutive LCs. METHODS: The retrospective investigation included 10 000 patients who underwent LC from July 1992 to June 2007. LC was performed by 4 teams of surgeons. The chief main surgeon of each team has had over 10 years of experience in hepatobiliary surgery. Calot's triangle was carefully dissected, and the relationship of the cystic duct to the CBD and common hepatic duct was clearly identified. A clip was applied to the cystic duct at the neck of the gallbladder and the duct was incised with scissors proximal to the clip. The cystic artery was dissected by the same method. Then, the gallbladder was dissected from its liver bed. A drain was routinely left at the gallbladder bed for 1-2 days postoperatively. RESULTS: No CBD injuries occurred in 10 000 consecutive LCs, and there were 16 duct leaks (0.16%). Among these, there were 10 Luschka duct leaks (0.1%) and 6 cystic duct leaks (0.06%). Four hundred thirty cases were converted to open cholecystectomy (OC), giving a conversion rate of 4.3%. After a mean follow-up of 17.5 months (range 6-24 months), no postoperative death due to LC occurred, and good results were observed in 95% of the patients. CONCLUSIONS: In our 10 000 LCs with zero CBD injuries, the techniques used and practices at our department have been successful. Surgeon's expertise in biliary surgery, preoperative imaging, precise operative procedures, and conversion from LC to OC when needed are important measures to prevent CBD injuries.

[Liver X receptor alpha inhibits LPS-induced inflammation by down-regulating IFR3 and GRIP1 in mouse Kupffer cells].

OBJECTIVE: To explore the possible mechanism of the inhibitory effect of liver X receptor alpha (LXRalpha) on lipopolysaccharide (LPS)-induced inflammation in mouse Kupffer cells (KCs). METHODS: The KCs isolated from the liver of male KM mice and cultured in RPMI 1640 containing 20% FBS for 24 h were divided into control, LPS, T0901317, and LPS+T0901317 groups with corresponding treatments. The expressions of LXRalpha, interferon regulatory factor 3 (IRF3) and glucocorticoid receptor interacting protein 1 (GRIP1) in the KCs were detected by Western blotting. The levels of interferon beta (IFNbeta), tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in the supernatant were detected by enzyme-linked immunosorbent assay (ELISA). RESULTS: The level of LXRalpha protein was highest in T0901317 group and lowest in LPS group, and was significantly higher in LPS+T0901317 group than in LPS group but lower than in T0901317 group (P<0.05). The levels of IRF3 and GRIP1 protein were the highest in LPS group, and significantly lowered by T0901317 treatment (P<0.05). The expression of IRF3 and GRIP1 proteins in LPS group and LPS+ T0901317 group were significantly higher than those in the control and T0901317 groups (P<0.05). The concentration of IFN-beta was significantly higher in LPS group than in the control and T0901317 group (P<0.05), and decreased in LPS+T0901317 group in comparison with that in LPS group (P<0.05). IFN-beta was the lowest in T0901317 group. The levels of TNF-alpha and IL-1beta were the highest in LPS group (P<0.05), and comparable between the other 3 groups (P>0.05). CONCLUSION: Pre-treatment with T0901317 before LPS stimulation can suppress the expressions of IRF3 and GRIP1 to inhibit the inflammation and hence Kupffer cell activation.