Hepatitis D virus (HDV) needs hepatitis B virus (HBV) as a helper to infect hepatocytes and spread. Co-infection with HDV and HBV may lead to accelerated progression and poor prognosis, but at present, the hazard and disease burden of HDV infection have been severely underestimated. This article summarizes the research advances in the epidemiology, clinical manifestations, diagnosis, and treatment of HDV infection, in order to provide a reference for more clinicians.

Objective To investigate the effect of epidermal growth factor (EGF) on the expression of Matrix metalloproteinase-9 (MMP-9) and the signalling pathways involved in the trophoblast cell line JEG-3. Methods The JEG-3 trophoblast cell line was used in this study. (1) JEG-3 cells were cultured with various concentrations of EGF (0, 1, 10,20 ng/ml) for 24 hours and the expression of MMP-9 was tested by western blotting and reverse transcription PCR (RT-PCR). (2) Western blotting and RT-PCR were also used to investigate the expression of MMP-9 expression after incubation for 0,4,12 and 24 hours with EGF treatment (10 ng/ml) in JEG-3 cells. (3) According to the different added ingredients, JEG-3 cells were divided into some groups: control group (without EGF), EGF group (exposure to l0ng/ml EGF),EGF + inhibitors group (exposure to 10 ng/ml EGF +20 ng/ml SB203580 or exposure to 10 ng/ml EGF + 10ng/ml U0126) inhibitors group (exposure to 20 ng/ml SB203580 or exposure to 10 ng/ml U0126). Western blotting were used to investigate the expression levels of MMP-9, nuclear factor kappa B (NF-kB) ,p38MAPK, phospho-p38MAPK (p-p38MAPK) , extracellular -signal regulated kinase (ERK) and phospho-ERK (p-ERK) protein in JEG-3 cells after incubation for 24 hours. Results (1) The profiles of MMP-9mRNA were increased by various concentrations of EGF (0, 1 , 10, 20 ng/ml) in JEG-3 cells after 24hculture. The expression of MMP-9 mRNA in JEG-3 cells exposure at 1 ng/ml of EGF (0. 567 ±0. 056) , 10ng/ml of EGF (1. 392 ±0. 133) , 20 ng/ml of EGF (1. 971 ±0. 067) were significantly higher respectively (P <0. 05) , compared with 0 ng/ml of EGF treatment (0. 166 ±0. 015). Similarly, MMP-9 mRNAs were also increased with the increasing incubation time. Compared to EGF (10 ng/ml) stimulation for 0 h (0.253 ±0.044), the MMP-9 mRNA profiles were 0. 470 ±0. 026, 1.061 ±0. 115, 1. 453 ±0. 180 for 4,12 and 24 hours, respectively (P < 0. 05). (2) In accordance to the mRNA profiles, the expression of MMP-9 protein was also increased by different concentrations of EGF (0,1, 10, 20 ng/ml) in JEG-3 cells after 24 h-culture. The abundance of MMP-9 protein in the three groups was 0. 043 ±0. 012, 0. 085 ±0. 008, 0. 142 ±0. 015, with a significantly higher expression, compared with 0 ng/ml of EGF treatment (0. 004 ±0.001, P < 0.05) respectively. Similarly, MMP-9 proteins were also increased with the increasing incubation time. Compared to EGF(10 ng/ml) stimulation for 0 h (0. 030 ±0. 009) , the profiles of MMP-9 protein were 0. 137 ± 0. 010, 0. 240 ± 0. 010, 1.240 ±0.061 for 4, 12 and 24 hours, respectively (P < 0.05). (3) Both p38MAPK and ERK signalling pathways were activated by EGF in JEG-3 cells. The expression of p-p38MAPK was significantly higher (without or with 10 ng/ml EGF, 234. 1 ± 4. 1 vs.260. 9 ± 2. 5 , P < 0. 05) , however, the p38 MAPK inhibitor SB203580 markedly suppressed the increase in p-p38MAPK content induced by EGF(227. 9 ±2. 4 vs. 260. 9 ±2. 5, P<0. 05). Similarly, the expression of p-ERK was significantly higher with EGF treatment (812. 2 ±3. 5) vs. without EGF group (453.4±5.8) (P <0. 05) , while the ERK inhibitor U0126 significantly inhibited the increased p-ERK content in response to EGF treatment (71. 0 ± 1. 2 vs. 812. 2 ± 3. 5, P < 0. 05) . (4) The p38MAPK inhibitor SB203580 significantly reduced the expression of EGF-induced MMP-9 (0. 645 ± 0. 270 vs. 1. 476 ± 0. 452, P < 0. 05)and NF-kB (0.530 ± 0.026 vs. 0.959 ± 0. 017, P < 0. 05) . (5) The ERK inhibitor U0126 also significantly reduced the expression of EGF-induced MMP-9 (0. 623 ±0. 030 vs. 2. 112 ±0. 056, P <0. 05)and NF-kB (0. 325 ± 0. 082 vs. 0. 939 ± 0. 153, P < 0. 05). Conclusion EGF induced the expression of MMP-9 in a time and dose-dependant manner in JEG-3 cells. EGF enhanced MMP-9 expression through the activation of p38MAPK and ERK signalling pathways in JEG-3 cells.