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.