Lymphocyte proliferation and activation induced cell death in model of primary biliary cirrhosis

Abstract

Objective To investigate the immune tolerance in animal models of primary biliary cirrhosis (PBC) by determining the cell proliferation and activation induced cell death (AICD).Methods C57BL/6 mice were injected with 5 mg/kg of polyI:C to develope PBC models. The lymphocytes and CD4~+ T cells were separated from spleens and livers 16 weeks later and were stimulated by M2, conA and anti-CD3 for cell proliferation and AICD. Expression of apoptosis related genes and proteins were detected by real time polymerase chain reaction (PCR) and Western blotting, respectively. Results ① The lymphocyte proliferation was 0.1988 ± 0.0111 in blank controls and 0. 2068±0. 0115 in PBS treated mice with no significant difference (P>0.05). However, an abundant lymphocyte proliferation was found in PBC mice (0. 358 ± 0. 022), which was higher than that in controls and PBS treated mice. The proliferation of lymphocyte from liver was greater than that from spleen in PBC mice (P 0.05). Furthermore, the apoptosis rate of T cells from livers were significantly lower than that from spleens in PBC mice (P<0.01). ③ The expressions of FasL and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in PBC mice were lower than those in PBS treated mice (P<0. 01), but there was no change in expression of Fas was found. ④ The expression of Fas-associated death domain-like interleukin-1-β-converting enzyme-inhibitory protein (FLIP_L) in PBC mice was higher than that in blank controls. Moreover, the expression of FLIP_L in livers was higher than that in spleens in PBC mice (P<0. 01). Conclusios The elevated expression of FLIP_L may inhibit AICD. Besides, the decreased expressions of FasL and TRAIL may also help in the enhancement of the anti-apoptotic ability in lymphocytes and in the aggravation of portal area inflammation. Key words: Primary biliary cirrhosis; Apoptosis; Immune tolerance; FLIP_L ; Caspase-8