The effect of serum amyloid protein A on the hepatitis development induced by concanavalin A

Abstract

Objective To investigate the effect of serum amyloid A (Saa) on the hepatitis development which induced by concanavalin A (ConA) and the action mechanism. Methods To establish hepatitis mouse model by injecting ConA in Saa over-expression transgenic mice (TG) and wild-type mice (WT), and the expression of monocyte chemotactic protein 1 (MCP1), chemokine 1α (MIP1α), chemokine 1β (MIP1β), chemokine IP10 (IP10) and Eotaxin gene were detected by real-time quantitative polymerase chain reaction (Real-time PCR) in liver tissue. The concentration of alanine transaminase (ALT) and glutamic oxalacetic transaminase (AST) in serum were measured by autoanalyzer. The concentration of tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-6 (IL-6) and interleukin-8(IL-8) in serum were measured by enzyme-linked immunosorbent assay (ELISA), and the expression of Saa, p-IκBα(Ser32/36) and IκBα proteins were detected by Western blotting. The isolation and purification of CD4+ T cells in liver and spleen were performed and tested by Flow cytometry. Results The overexpression of MCP1, MIP1α, MIP1β, IP10, Eotaxin gene in TG group (0.61±0.13, 0.89±0.15, 0.76±0.12, 0.37±0.08, 0.98±0.17) were significantly higher than WT group (0.13±0.03, 0.27±0.02, 0.16±0.06, 0.07±0.02, 0.34±0.07), (P=0.001, 0.001, 0.001, 0.021, 0.001, respectively)). At 6 h, the concentration of ALT (16.2±3.1) U/L and AST (18.8±4.2) U/L were significantly higher than WT group (P=0.002, 0.001). The secretion of TNF-α, IFN-γ, IL-6 and IL-8 were higher in serum of TG mice [(813.6±114.2), (64.5±8.9), (1 045.8±138.6), (43.4±5.5) pg/ml] than in WT mice [(253.1±33.5), (10.5±6.7), (374.1±53.7), (24.8±3.4) pg/ml] (P=0.011, 0.006, 0.005, 0.014). Flow cytometry indicated that the rates of CD4+ T cell and F4/80+ CD11b+ macrophage cell in liver of TG group (60.72±3.65)% and (9.86±0.58)% were significantly higher than WT group mice (35.41±2.45)% and (2.73±0.51)%, (P=0.011, 0.014). Western blotting indicated that the levels of p-IκBα (Ser32/36) protein levels significantly increased, while decreased after CU-CPT22 treatment in TG mice liver tissue. Conclusion Saa overexpression promoted hepatitis development by inducing chemokines expression in a Toll like receptors 2 (TLR2) activation-dependent manner, and play a role by increasing the number of CD4+ T cells and macrophages Key words: Saa; Concanavalin A; Chemokine; T cell; Hepatitis