Complement C4a inhibits the secretion of hepatitis B virus screened by surface-enhanced laser desorption ionization time-flight mass spectrometry-based ProteinChip analysis.

Purpose: Chronic hepatitis B (CHB) is a kind of chronic liver disease caused by persistent hepatitis B virus (HBV) infection. The study aims to seek the factors of host resistance to HBV and investigate their roles.
Experimental Design: Protein profiles of 58 healthy controls and 121 CHB patients were obtained by SELDI-TOF/MS. Predicted protein was validated by ELISA. Protein expression was evaluated by Western blot in the persistently HBV expressing cell line HepG2.2.15 and non-HBV expressing cell line HepG2. The level of HBV DNA was subsequently detected by quantitative real-time PCR in HepG2.2.15 cells with complement C4a treatment.
Results: Significantly altered protein peaks were found through statistical analysis, and m/z 4300 was predicted by databases and successfully matched with the fragment of complement C4a. According to ELISA, serum complement C4a was found to be significantly lower in CHB patients compared with healthy controls (p < 0.001) and the area under receiver operating characteristics curve is 0.78. Furthermore, complement C4a showed lower expression in HepG2.2.5 cells and the secretion of HBV DNA was inhibited by complement C4a.
Conclusions and Clinical Relevance: The present study implied the important role of complement C4a in inhibiting the HBV DNA secretion in CHB.
(© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)