Study On Genital Chlamydial Spreading To Gastrointestinal Tract And An Oral Live Attenuated Chlamydia Vaccine

Background:Chlamydia trachomatis is one of the main pathogens of sexually transmitted diseases,which may lead to tubal fibrosis and even tubal infertility.C.trachomatis is also commonly detected in the human gastrointestinal tract.Animal studies have shown that the transmission of Chlamydia from the genital tract to the gastrointestinal tract may prime CD8~+T cells and promote the pathogenicity of Chlamydia in the genital tract.However,the mode of chlamydial transmission to the gastrointestinal tract and the mechanism of the generation of pathogenic CD8~+T cells remain unclear.At the same time,it has been found that chlamydial gastrointestinal infection,when occuirng prior to genital tract infection,can induce protective transmucosal immunity in the genital tract.However,this finding has not been used for developing effective chlamydial vaccine.Objective:The purposes of this study were to reveal the pathways in which Chlamydia spreads from the genital tract to the gastrointestinal tract,to determine the mechanisms of the induction of pathogenic CD8~+T cells by gastrointestinal Chlamydia,and to evaluate the efficacy of an attenuated Chlamydia as a live oral vaccine in protecting the genital tract from chlamydial infection.Methods:(1)This study compared the long-term live chlamydial organisms recovered from both vaginal and rectal swabs after intrvaginal or intravenous inoculation of Chlamydia in wild-type mice with or without spleenectomy,and temporal distribution of live chlamydial organisms in mouse tissues in the early stage of infection.(2)This study compared the long-term live chlamydial organisms recovered from both vaginal and rectal swabs,the temporal distribution of live chlamydial organisms in mice tissues,and the incidence of hydrosalpinx after intravaginal inoculation of Chlamydia in wild-type mice with or without the immunomodulatory drug fingolimod(FTY720).(3)Firstly,after intravaginal inoculation of Chlamydia in OT1 mice,C57BL/6J mice and C57BL/6J mice with CD8~+T cell depletion,the long-term live chlamydial organisms recovered from both vaginal and rectal swabs,the incidence and severity of hydrosalpinx,the oviduct dilation and inflammatory infiltration scores were compared among the three groups of mice.Secondly,CD8~+T cells from C57BL/6J mice with or without chlamydial gastrointestinal immunization were used as donor cells,and were adoptive transfered at different time points after intravaginal inoculation of Chlamydia in OT1 recipient mice.OT1 mice without adoptive transfer were intravaginally inoculated with Chlamydia and used as control.the long-term live chlamydial organisms recovered from both vaginal and rectal swabs,the incidence and severity of hydrosalpinx and the inflammatory infiltration were compared between recipient mice and control mice.(4)In this study,C57BL/6J mice were immunized with the attenuated Chlamydia mutants vaginally or orally,and the immunized and unimmunized mice were challenged with wild-type Chlamydia in the genital tract.The long-term live chlamydial organisms recovered from both vaginal and rectal swabs,the incidence and severity of hydrosalpinx,and the oviduct dilation and inflammatory infiltration scores were compared between immunized and unimmunized mice.Results:(1)There was no significant difference in the vaginal and rectal shedding course between mice with and without splenectomy after intravaginal or intravenous inoculation.In the presence of the spleen,the intravenous Chlamydia was first concentrated in the spleen,and reached the stomach first and then the rest of the gastrointestinal tract.After splenectomy,intravenous Chlamydia was first concentrated in the liver,and was able to spread to the large intestine lumen but without a preceding presence in the stomach.(2)Within 35 days after intravaginal infection in C57BL/6J mice,the rectal infection burden in FTY720 treatment group was significantly lower than that in control group.From day 42,there was no significant difference in rectal infection burden between FTY720 treatment group and control group.For CBA/J mice which are more susceptible to chlamydial infection,the infection burden in gastrointestinal tissues on day 4 and 7 and rectal swabs on day 14 and 21 after intravaginal inoculation of FTY720 treatment group were lower than those of control group.(3)Compared to C57BL/6J mice,OT1 mice and C57BL/6J mice with CD8~+T cell depletion had lower incidence of hydrosalpinx after intravaginal infection of Chlamydia,and the severity of hydrosalpinx of OT1 mice was lower.When the donor cells were na(?)ve CD8~+T cells,compared to the control group which was without adoptive transfer,only the group received the transfer and the intravaginal infection simultaneously had higher incidence and severity of hydrosalpinx,and oviduct dilation and inflammatory infiltration scores.When the donor cells were immunized CD8~+T cells and transferred at the same time of intravaginal infection,2 weeks after infection or 3 weeks after infection,the incidence and severity of hydrosalpinx and the oviduct dilation and inflammatory infiltration scores were higher than those of control group.(4)Oral immunization of plasmid-free Chlamydia and p GP3-deficient Chlamydia could induce protective transmucosal immunity against challenge infection and pathogenicity in the upper genital tract of wild type Chlamydia.After oral immunization,the p GP3-deficient mutant completely failed to spread to gastrointestinal tract and produce infectious particles in the rectal swabs.However,oral immunization with p GP3-deficient mutant fully protected mice from developing pathology induced by wild-type Chlamydia in the upper genital tract.Conclusion:The spleen is not essential for genital/hematogenous Chlamydia to spread to the gastrointestinal tract.FTY720 treatment which is able to inhibit the migration of dendritic cells and lymphocytes does delay but not completely block genital chlamydial spreading to the GI tract.Pathogenic CD8~+T lymphocytes induced by Chlamydia in the gastrointestinal tract are chlamydial antigen specific.Na(?)ve CD8~+T cells have to be primed within 2 weeks of chlamydial infection to promote hydrosalpinx while Chlamydia-primed CD8~+T cells can promote hydrosalpinx for more than 3 weeks after chlamydial infection.p GP3 may be targeted for developing a safe and effective live attenuated oral vaccine.