Phenotypic and functional characteristics of natural killer cells in HBV cirrhotic patients / 解放军医学杂志

ABSTRACT

Objective To analyze the phenotypic and functional characteristics of hepatic and peripheral natural killer (NK) cells in HBV cirrhotic patients, and further confirm the key role of NK cells in the immunopathogenesis of liver fibrosis. Methods Thirty HBV cirrhotic patients were recruited for this study in the First People's Hospital of Zhengzhou and Fifth Medical Center of Chinese PLA General Hospital from January 2015 to January 2017, meanwhile thirty age-and sex-matched healthy individuals were enrolled as health controls. Liver biopsies were collected from 10 HBV cirrhotic patients, and 8 healthy liver tissue samples were obtained from the healthy donors whose livers were used for liver transplantation. The frequency, phenotypic and functional characteristics of hepatic and peripheral NK cells from the two groups were analyzed by using multicolor flow cytometry. The killing activities of NK cells against HSCs were explored using LX-2 cell model (a cell line of HSCs) in vitro. Results Compared with health controls, the percentages of hepatic and peripheral NK cells were reduced significantly in cirrhotic patients (U=8.5, P=0.006; U=184.0, P<0.001, respectively); the expression levels of activation markers CD69 (U=102.0, P=0.009), HLA-DR (U=82.5, P<0.001) and CD38 (U=0.0, P=0.029) were increased; the expressions of functional molecule granzyme B (U=0.0,P=0.004) was decreased in peripheral NK cells, and perforin and Granzymes were also decreased in hepatic NK cells except TRAIL that was up-regulated (U=4.0, P=0.026), especially the change of perforin (U=4.0, P=0.034); the functional decrease in IFN-γ production (U=2.0, P=0.032) was observed in vitro in hepatic NK cells and the reduction of CD107a degranulation and IFN-γ production were both observed in hepatic and peripheral NK cells (U=88.0, P=0.018; U=13.0, P<0.001, respectively); purified NK cells from peripheral blood of HBV cirrhotic patients could induce less 7AAD– Annexin V+ early apoptotic LX2 cells and 7AAD+ Annexin V+ late apoptotic LX2 cells compared with those from health controls (U=6.5, P=0.025; U=2.0, P=0.002, respectively). Conclusions NK cells from HBV cirrhotic patients displayed a decreased frequency, activation increase, functional decrease in CD107a degranulation and IFN-γ production, and cytolytic activities decrease against HSCs in response to various stimulators in vitro compared with those from health controls. These findings demonstrate an impaired anti-fibrotic function of NK cells' in HBV cirrhotic patients and further clarify the immunopathogenesis of liver fibrosis.