Effect of ubiquitination hepatitis B virus core antigen on inducing dendritic cells autophagy to enhance specific cytotoxic T lymphocyte responses / 中华传染病杂志

ABSTRACT

Objective:To clarify the effect of ubiquitination hepatitis B virus core antigen (Ub-HBcAg) on dendritic cells (DC) autophagy, and to explore the mechanism of autophagy in enhancing DC antigen presentation and inducing hepatitis B virus-specific cytotoxic T lymphocyte (CTL) responses.Methods:Ub-HBcAg lentiviral vector (LV-Ub-HBcAg), lentiviral vector-hepatitis B virus core antigen (LV-HBcAg) and no-load plasmid LV (LV) were constructed and packaged. DC2.4 cells were divided into LV-Ub-HBcAg group, LV-HBcAg group and LV group. The blank control group (NC group) was also set. The protein expression of autophagy-related protein P62, microtubule associated protein 1 light chain 3 beta (LC3B), autophagy related 5(ATG5) and Beclin-1 were detected by Western blotting. The expressions of co-stimulatory molecules such as CD86, CD80 and major histocompatibility complex (MHC)-Ⅱ were detected by flow cytometry. Cell counting kit-8 (CCK-8) method was used to detect T lymphocytes proliferation. The non-radioactive lactic acid dehydrogenase (LDH) release method was applied to detect the killing ability of CTL. Statistical analysis was conducted by independent sample t test. Results:The relative protein expressions of LC3B-Ⅱ/LC3B-Ⅰ, Beclin-1 and ATG5 in NC group were 0.445±0.076, 0.522±0.026 and 0.761±0.038, respectively, which were all lower than those in LV-Ub-HBcAg group (0.926±0.021, 0.919±0.016 and 1.451±0.028, respectively). The relative protein expression of P62 in the NC group was higher than that in LV-Ub-HBcAg group ((1.875±0.016) vs (0.647±0.121)). The differences were all statistically significant ( t=6.102, 9.842, 17.490 and 10.590, respectively, all P<0.01). The expressions of CD86 (75.51%), CD80 (83.35%), MHC-Ⅱ (66.66%) in the LV-Ub-HBcAg group were high, and those in the NC group were 8.03%, 7.49%, 0.04%, respectively. The specific CTL killing rate ((65.310±2.091)%) of the LV-Ub-HBcAg group was significantly higher than both NC group ((14.400±0.497)%) and LV-HBcAg group ((54.870±1.443)%), and the differences were both statistically significant ( t=23.690 and 4.111, respectively, both P<0.05). Conclusion:Ub-HBcAg promotes the DC autophagy, up-regulates the expressions of costimulatory molecules on cell surface of DC to induce the maturation and activation, and then stimulates T lymphocyte to induce a stronger specific CTL response under the effort of ubiquitination.