Thiazolidinedione treatment inhibits bile duct proliferation and fibrosis in a rat model of chronic cholestasis.

AIM: To investigate the effects of troglitazone (TGZ), an anti-diabetic drug which activates peroxisome proliferator-activated receptor-gamma (PPAR-gamma), for liver tissue repair, and the development of ductular reaction, following common bile duct ligation (BDL) in rats. METHODS: Rats were supplemented with TGZ (0.2% w/w in the pelleted food) for 1 wk before BDL or sham operation. Animals were killed at 1, 2, or 4 wk after surgery. RESULTS: The development of liver fibrosis was reduced in rats receiving TGZ, as indicated by significant decreases of procollagen type I gene expression and liver hydroxy-proline levels. Accumulation of alpha-smooth-muscle actin (SMA)-expressing cells surrounding newly formed bile ducts following BDL, as well as total hepatic levels of SMA were partially inhibited by TGZ treatment, indicating the presence of a reduced number and/or activation of hepatic stellate cells (HSC) and myofibroblasts. Development of the ductular reaction was inhibited by TGZ, as indicated by histochemical evaluation and hepatic activity of gamma-glutamyl-transferase (GGT). CONCLUSION: Treatment with thiazolidinedione reduces ductular proliferation and fibrosis in a model of chronic cholestasis, and suggests that limiting cholangiocyte proliferation may contribute to the lower development of scarring in this system.

Differential requirement of members of the MAPK family for CCL2 expression by hepatic stellate cells.

Hepatic stellate cells (HSC) coordinate the liver wound-healing response through secretion of several cytokines and chemokines, including CCL2 (formerly known as monocyte chemoattractant protein-1). In this study, we evaluated the role of different proteins of the MAPK family (ERK, p38(MAPK), and JNK) in the regulation of CCL2 expression by HSC, as an index of their proinflammatory activity. Several mediators activated all three MAPK, including TNF, IL-1, and PDGF. To assess the relative role of the different MAPKs, specific pharmacological inhibitors were used; namely, SB203580 (p38(MAPK)), SP600125 (JNK), and PD98059 (MEK/ERK). The efficacy and specificity of the different inhibitors in our cellular system were verified analyzing the enzymatic activity of the different MAPKs using in vitro kinase assays and/or testing the inhibition of phosphorylation of downstream substrates. SB203580 and SP600125 dose-dependently inhibited CCL2 secretion and gene expression induced by IL-1 or TNF. In contrast, inhibition of ERK did not affect the upregulation of CCL2 induced by the two cytokines. Finally, activin A was also found to stimulate CCL2 expression and to activate ERK, JNK, p38, and their downstream targets. Unlike in cells exposed to proinflammatory cytokines, all three MAPKs were required to induce CCL2 secretion in response to activin. We conclude that members of the MAPK family differentially regulate cytokine-induced chemokine expression in human HSC.

Late hepatic artery thrombosis after orthotopic liver transplantation.

Late hepatic artery thrombosis (HAT) is a rare complication after orthotopic liver transplantation (OLT), conventionally described as occurring more than 30 days after surgery. Only a few reports document its course. In a consecutive series of 634 OLTs (704 grafts), 11 patients (1.7%) had late HAT, diagnosed a median of 6 months (range, 1.8 to 79 months) after OLT. Clinical variables were compared with those of 415 patients without HAT who had a complete database and follow-up, including cytomegalovirus (CMV) surveillance. At presentation, 11 patients had fever, 4 patients had jaundice. Hepatic abscesses were present in 6 patients (3 patients with biliary leak), 4 patients had biliary tree necrosis (2 patients with biliary leak), and 1 patient had no biliary complications. Five patients (45%) underwent accessory hepatic artery anastomosis versus 73 patients (17%) without HAT (P <.05). Five patients (45%) with late HAT had CMV infection versus 14% without HAT (P <.05). Two episodes of late HAT (11 and 79 months) occurred in patients who underwent re-OLT for early HAT (3.9%). Re-OLT was performed in 8 patients a median of 11 days (range, 3 to 37 days) after diagnosis (preceded by intravenous antibiotics and percutaneous drainage). The other 3 patients underwent partial hepatectomy (1 patient), external percutaneous drainage as unfit for surgery (1 patient), and antibiotic therapy only (1 patient). Death occurred in 4 patients who underwent re-OLT (50%) because of septicemia at 11, 23, and 60 days after re-OLT and 17 days after a third OLT. There was one late death (30 months) after partial hepatectomy (hepatitis C recurrence) and one death 6 months after long-term biliary drainage because of sepsis. The 5 survivors have good health with normal liver function test results at a median 52 months (range, 6 to 57 months). In conclusion, late HAT presents with fever caused by hepatic abscesses or biliary leak associated with biliary ischemia and necrosis. CMV infection and accessory hepatic artery anastomosis are risk factors for late HAT in our cohort. Early intervention followed by re-OLT can salvage patients.

Bacterial infection in cirrhosis impairs coagulation by a heparin effect: a prospective study.

BACKGROUND: Bacterial infections have been postulated as a trigger for variceal bleeding in cirrhotic patients, and impair coagulation evaluated by thrombelastography (TEG). Endogenous heparinoids have been detected after variceal bleeding and during liver transplantation in some cirrhotics using heparinase-modified-TEG. AIM: To assess if bacterial infection is associated with endogenous heparinoids in cirrhotics, thus impairing coagulation. METHODS: Native and heparinase-modified-TEG (cleavage of heparin and heparan-sulphate) was performed in 60 cirrhotics (Grade A, 2; B, 30; C, 28): 30 infected [septicaemia, 6 (culture positive); 6 (culture negative); spontaneous bacterial peritonitis, 10; chest infection, 4; others, 4], 30 not infected, and five infected patients without liver diseases, comparing TEG parameters r, alpha, and ma. Eight cirrhotics were studied before and after infection. The diagnosis of presence and type of infection was based on international standard criteria. RESULTS: A significant heparin effect was found only in infected cirrhotics (28 of 30) with significant changes in r (P=0.0003), alpha (P<0.0001), and ma (P<0.0001), but in none of those not infected. This effect completely reversed in the eight evaluated after resolution of infection. There was no heparin effect in infected non-cirrhotics. CONCLUSIONS: A heparin effect was only found in cirrhotic patients with infection, further confirming that infection significantly modifies coagulation in cirrhotic patients.

[Thiazolidinediones and PPARgamma system in repair of liver damage]. / Tiazolidindieni e sistema PPAR-gamma nella riparazione del danno epatico.

PPAR-gamma belongs to the nuclear hormone receptor superfamily and its ligands include antidiabetic drugs of the thiazolidindione class, and endogenous molecules, including eicosanoids and fatty acids. PPAR-gamma is involved in the pathophysiology of obesity and type II diabetes. More recently, accumulating evidence suggests its role in atherosclerosis, inflammation and cancer. Recent data obtained in cellular models of liver fibrosis indicate that PPAR-gamma activation results in the inhibition of the processes leading to the development of liver fibrosis. These studies identify potential novel therapeutic strategies for the treatment of liver fibrosis.