High-mobility Group Box 1 And Scavenger Receptor A: Novel Applications In The Management Of Patients With Cholangitis

Background:Cholangitis is the inflammation of biliary ducts which usually begins extra-hepatic and easily spreads intra-hepatic, causing bacteremia. Acute obstruction of biliary tract with the presence of pus is severe form of cholangitis know as Acute Obstructive Suppurative Cholangitis(AOSC) which has very high mortality. It is experienced that the Charcot’s triad and Reynold pentad are difficult to use in clinical practice for the management of cholangitis and recently published “Updated Tokyo Guidelines for management of cholangitis and cholecystitis in 2013 is lack of evaluation and revision.High Mobility Group Box 1(HMGB1) is a proinflammatory cytokine which is found to play an active role during the pathogenesis of inflammatory processes. In response to infection, HMGB1 acts as an important proinflammatory cytokine which may lead in the damage of cells and tissues. This process may continue to metabolic acidosis, multi-organ dysfunction syndrome(MODS) and sepsis. Recent studies have reported associations between HMGB1 and inflammation. But the correlation between HMGB1 and AOSC pathogenesis is not yet fully understood. We detect whether HMGB1 is involved in the pathogenesis of AOSC.Scavenger receptor A(SRA) is a transmembrane glycoprotein and mainly distributed in hepatic Kupffer cells. It is SRA that relates to defensive reaction which mediates macrophage clearing and inactivating endotoxin. The relation between SRA and liver tissue during inflammation is not clearly described in the literatures. We intend to commence from AOSC and establish animal model of Wistar rats cholangitis so that we might investigate the expression of SRA and their relations to endotoxin, TNF-α, IL-6 and endotoxic hepatic injury in AOSC in order to uncover the mechanism of the conversion of Kupffer cells from immune defensive cells to inflammatory response cells during AOSC from histology, cell, molecule and gene, which may provide evidence for the establishment of new therapeutic regimen for AOSC.Purpose:This paper include two parts,(I) relationship between HMGB1 and Cholangitis patients and(II) relationship between SRA and mouse model of cholangitis to provide evidence for the establishment of new management regimen for Cholangitis.Methods: We collected samples of peripheral blood from 23 patients with AOSC and 23 healthy volunteers who served as normal controls. All were tested for the HMGB1 m RNA, the HMGB1 protein, Tumor Necrosis Factor- alpha(TNF-alpha) and Interleukin-10(IL-10). HMGB1 m RNA was tested using RT-PCR.HMGB1 Protein was tested using Western blot. TNF-alpha and IL-10 were tested using ELISA.Also, Mouse model of AOC were reproduced by ligating choledochus and injecting Escherichia coli O111B4 into it. The concentration of plasma endotoxins were assayed by litmus test. The level of tumor necrosis factor-alpha(TNF-alpha) and Interleukin-6(IL-6) in plasma were determined with enzyme-linked immunosorbent assay(ELISA). The expression of SRA protein in liver tissue was assayed by immunohistochemistry, and the expression of SRA m RNA in liver tissue were detected via light microscope.Results: The expression of HMGB1 m RNA and HMGB1 Proteins were higher in AOSC group than that of normal controls(P<0.01) and it gradually decreased to normal level after the treatment of the disease(P<0.01). The content of TNF-alpha and IL-10 in peripheral blood of AOSC patients was significantly higher than the content of normal controls(P<0.01) and they decreased to normal level after the necessary treatment(P<0.01).The plasma endotoxins concentrations in AOC were progressively increased with the time prolonged. With increasing endotoxin, the level of TNF-alpha and IL-6 were also markedly increased. The SRA protein and m RNA expression were obviously decreased with prolonged experimental time. There were significant difference among experimental groups and control groups(P<0.01). Liver histopathological study showed that the hepatic injury was gradually aggravated with the time prolonged. Massive inflammatory cells infiltration and large-area hepatocytes degeneration and necrosis were found in later period.Conclusions: The level of HMGB1 m RNA and HMGB1 Protein are elevated in patients with AOSC which may have important role in the inflammation of bile duct and seems to be associated with the development of sepsis suggesting its importance in the management of AOSC-induced sepsis.The expression of SRA in Kupffer cells gradually decreases with progressively increasing plasma endotoxin levels in AOC. Its ability of clearing and inactivating LPS correspondingly descends. In the meantime, endotoxin strengthen activating Kupffer cells. Hence, it might be one of the important mechanism for the conversion of Kupffer cells from immune defensive cells to inflammatory response cells. We found, the decreased expression of SRA in Kupffer cells is responsible for endotoxin hepatic injury in AOC.