Regulation of Chlamydia trachomatis infection in the female genital tract by type I and type II interferons
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Following an intravaginal inoculation with Chlamydia trachomatis , mice deficient in type I interferon receptor IFNαR1 (IFNαR1 -/- ) significantly increased the yield of live chlamydiae on days 3 & 5 but reduced it to the level of wild-type mice by day 7, while mice deficient in type II interferon receptor IFNγR1 (IFNγR1 -/- ) significantly increased the chlamydial yield by day 5 and the increase persisted throughout the remainder of the infection course. These observations reveal a temporal division of labor between type I & II interferons in regulating C. trachomatis infection in the female genital tract. Interestingly, mice deficient in both IFNαR1 & IFNγR1 exhibited higher mortality and shed more chlamydial organisms than IFNγR1 -/- mice by week 6, suggesting that IFNαR1 remains critical for inhibiting C. trachomatis at late stages. An anti-IFNαR1 antibody blockade significantly increased chlamydial yields in IFNγR1 -/- mice, suggesting that the anti-chlamydial activities of type I & II interferon systems are both distinct and overlapping throughout the infection course. Furthermore, the anti-chlamydial activity of type I interferon signaling is localized to the lower vagina, while that of type II interferon signaling is localized to the upper vagina. Thus, we have demonstrated that type I & II interferons function complementarily and synergistically in time and space to control C. trachomatis infection, laying the foundation for further elucidating the mechanisms of IFN regulation of chlamydial infection and for developing interventional and preventive strategies against C. trachomatis in the female genital tract.
Importance
Lack of information on the precise roles of type I and type II interferons during chlamydial infection has hindered the development of interferon-based strategies to prevent chlamydial infection and pathogenicity. The current study has revealed a temporal division of labor between type I & type II interferons in regulating chlamydial infection in the female genital tract, with type I acting earlier than type II during the innate phase. Nevertheless, type I remains critical for cooperating with type II to suppress chlamydia 6 weeks after infection. Finally, type I interferons seem to mainly target chlamydial infection in the lower vagina, while type II interferons target the infection in the upper vagina. These new findings on the distinct and overlapping roles of type I and type II interferons in regulating chlamydial infection may guide the development of interferon-based precision strategies to reduce chlamydial infection and pathogenicity in the female genital tract.
