Preliminary study on genital tract immune injury in mice induced by pORF5 plasmid protein of Chlamydia trachomatis

Abstract

Objective To investigate the immune injury in genital tract of BALB/c mice induced by plasmid protein pORF5 of Chlamydia trachomatis and its possible mechanism.Methods GST(glutathione-S-transferases)-pORF5 fusion protein was expressed and digested with PreScission Protease to obtain the target protein without GST tag.After further purification and endotoxin removal,pORF5 protein was injected into the posterior fornix of BALB/c mice on day 1,3 and 6,while the control groups were injected with PBS or GST protein respectively,and then all the mice were sacrificed on day 7 to evaluate genital tract gross pathology and histopathological characterization.The levels of TNF-α,IL-1β and IL-6 in serum,splenocytes culture supernatant and vaginal douche were detected by ELISA.Results Mice in pORF5 group developed different degrees of swelling in isthmic portion and ampulla of uterine tube,connective tissue adhesion and hydrosalpinx in the genital tract tissues,while the PBS group and the GST group did not show any obvious change.The inflammatory score showed that the genital tract pathology in pORF5 group was much more severe than PBS and GST control groups (P＜0.O1).The levels of TNF-α,IL-1β and IL-6 in vaginal douche and splenocytes culture supernatants in pORF5 group were obviously higher than those of PBS and GST groups (P＜0.05).The levels of TNF-α and IL-1β in serum were also higher than those of GST and PBS groups (P＜0.01).Conclusion pORF5 plasmid protein could induce pathological immune response in the genital tract of BALB/c mice,which may be associated with the increase of the production of the inflammatory cytokines TNF-α,IL-1β and IL-6 in BALB/c mice. Key words: Chlamydia trachomatis; pORF5 plasmid protein; Immune injury; Cytokine