Objective      To investigate the relationship of the serum level of interleukin-22 (IL-22)  with the liver function impairment

progression and prognosis of acute hepatitis E virus (HEV) infection.       Methods      A total of 47 acute HEV infection patients including 26 pre-existing liver cirrhosis patients and 21 simple HEV infection patients admitted in

our institute from February 2003 to June 2013 were enrolled in the study. Based on acute-on-chronic liver failure (ACLF) arose or not

the liver cirrhosis patients were divided into an ACLF group (n=13) and a non-ACLF group (n=13). In addition

we set 15 healthy controls. Serum samples were collected every 3 to 7 days. Serum IL-22

IL-6 and IFN-γ levels were quantified by ELISA.        Results      Compared with the healthy controls

the IL-22 and IL-6 concentrations were significantly elevated in the patients with simple HEV infection (

P

≤0.001)

while IFN-γ level had no significant difference between the 2 groups. Meanwhile

higher IL-22 and IL-6 levels appeared in patients with pre-existing liver cirrhosis than those with simple HEV infection (

P

0.001). The IL-22

IL-6 and IFN-γ levels were significantly higher in the ACLF group than in the non-ACLF group (

P

0.010). Patients with elevated IL-22 and IL-6 concentrations showed higher total bilirubin level and lower PTA index. In 6 acute HEV infection patients who concurrently suffered ACLF

the IL-22 concentration decreased as the liver function injury faded away and disease recovered.       Conclusion      IL-22 appears to be an important mediator of the inflammatory response in acute HEV infection. IL-22 level may be used as an indicating parameter of liver damage and prognosis.