Hepatic Aquaporin 10 Expression Is Downregulated by Activated NFκB Signaling in Human Obstructive Cholestasis.

Background and Aims: Recent studies reported that the hepatic expression of AQP8 and AQP9 was downregulated in bile duct-ligated (BDL) rats and that overexpression of human AQP1 in the rat liver attenuated cholestasis. However, the hepatic expression of AQP10 and its regulatory mechanism in human cholestasis remain unclear.

Methods: Serum and liver samples were collected from 34 patients with obstructive cholestasis and from 12 control patients. Eight-week-old male C57BL/6J mice were intravenously injected with an adeno-associated virus 8 (AAV8) encoding human AQP10 driven by a hepatocyte-specific promotor (AAV8- promotor-) for functional studies. Constructs of the AQP10 promoter and PLC/PRF/5-ASBT cell lines were used for regulatory mechanism studies.

Results: AQP10 was significantly downregulated in patients with obstructive cholestasis and negatively associated with the serum levels of total bile acid (TBA). The hepatocyte-specific overexpression of  significantly attenuated the cholestatic liver injury and intrahepatic bile acids (BA) accumulation in BDL mice. Conjugated BAs, such as TCA and inflammatory factor TNFα, significantly repressed AQP10 expression. Furthermore, NFκB p65/p50 directly bound to the AQP10 promotor and decreased its activity in PLC/RPF/5- cells and in the livers of patients with obstructive cholestasis. However, these changes were diminished by BAY 11-7082 (a specific inhibitor of NFκB signaling).

Conclusion: We are the first to report that AQP10 was significantly decreased in patients with obstructive cholestasis. AQP10 overexpression significantly attenuated cholestatic liver injury in BDL mice. Therefore, overexpression of in the liver may be a valuable strategy for cholestasis intervention.