Inhibition of Apoptosis by Gamma Interferon in Cells and Mice Infected withChlamydia muridarum(the Mouse Pneumonitis Strain ofChlamydia trachomatis)

Open Access
Publisher Website
Google Scholar
Abstract
The effect of gamma interferon (IFN-γ) on apoptosis due to infection byChlamydia muridarum(the mouse pneumonitis strain ofChlamydia trachomatis) was studied in epithelial cells in culture and in the genital tracts of mice. IFN-γ concentrations that induce the formation of aberrant, persistent chlamydiae inhibit apoptosis due toC. muridaruminfection. In cells treated with an IFN-γ concentration that leads to the development of a heterogenous population of normal and aberrantChlamydiavacuoles, apoptosis was inhibited preferentially in cells that contained the aberrant vacuoles. The inhibitory effect of IFN-γ appears to be due in part to expression of host cell indoleamine 2,3-dioxygenase activity, since inhibition of apoptosis could be partially reversed through coincubation with exogenous tryptophan. Apoptotic cells were observed in the genital tracts of wild-type mice infected withC. muridarum, and a significantly larger number of apoptotic cells was detected in infected IFN-γ-deficient mice. These results suggest that IFN-γ may contribute to pathogenesis of persistentChlamydiainfections in vivo by preventing apoptosis of infected cells.