TUNEL labeling did not reveal apoptosis of any cell type in the liver, including endothelial cells

usion development nor formation of infectious progeny of C. muridarum. Thus, distinct chlamydial species exhibit differential sensitivities to IFNc in host resistance: Growth of C. trachomatis in MEFs is arrested in response to IFNc, whereas growth of C. muridarum is not affected in response to IFNc. Irga6, Irgd, Irgm2 and Irgm3 interact specifically with early C. trachomatis inclusions in response to IFNc Since IFNc can upregulate IRG expression in C. trachomatis infected murine cells, we investigated the 16522807 involvement of Control of Ctr via Irga6 MEFs. Thus, fusion of C. trachomatis inclusions with autophagosomes is a prerequisite for lysosomal degradation. Absence of Irga6 stimulates growth of C. trachomatis and induces resistance against IFNc-induced killing 11741928 To further analyze the role of Irga6 in IFNc-mediated growth restriction of C. trachomatis, we examined Irga6-knockout MEFs. Untreated Irga62/2 cells infected for 48 h with C. trachomatis generated larger inclusions and purchase AG1024 yielded a 4 to 5-fold increase in the number of infectious progeny, compared to untreated WT cells. IFNc treatment did not inhibit the growth of inclusions in Irga62/2 cells, but they were bigger than in control untreated WT MEFs. Surprisingly, infected Irga62/2 MEFs were sensitive to IFNc exposure, which resulted in partial destruction and loss of infected host cells of the monolayer. Therefore, the chlamydial infectivity measured in each sample had to be normalized to the surviving host cells, determined via an LDH release assay. This data clearly indicated that IFNc treatment of Irga62/2 cells did not reduce infectivity. Association of Irga6 with early chlamydial inclusions is blocked in Atg52/2 MEFs in response to IFNc To address the role of IFNc-induced IRGs in the regulation of C. trachomatis survival, we examined the intracellular distribution of IRGs at 3 h p.i. in Atg52/2 MEFs. Surprisingly, upon IFNc stimulation most bacterial inclusions colocalized with Irgd, Irgm2 and Irgm3 ; results comparable to data obtained from IFNc-stimulated WT MEFs. Strikingly, only 2% of inclusions colocalized with Irga6, as compared to 83% in IFNc-treated WT MEFs. As expected, IRG proteins did not colocalize with early inclusions of C. muridarum. These results strongly suggest an important role for Irga6 in autophagy-mediated control of C. trachomatis infection. Control of Ctr via Irga6 Similar to our data from WT and Atg52/2 MEFs, IFNc treatment of Irga62/2 MEFs at 3 h p.i. increased the association of Irgd, Irgm2 and Irgm3 with early bacterial inclusions. As expected, no signal for Irga6 was detected in IFNc-exposed or unexposed Irga6deficient MEFs. In contrast, no IRG proteins localized to C. muridarum inclusions. Next, we investigated whether enhanced propagation of C. trachomatis in Irga62/2 MEFs was connected with a lack of autolysosomal features of inclusions. Indeed, IFNc treatment of Irga62/2 MEFs did not induce an association of LAMP1 with chlamydial inclusions. Numbers of bacteria colocalizing with LAMP1 in IFNc induced Irga62/2 cells were comparable to untreated WT MEFs. Consistently, only approximately 1% of bacterial inclusions colocalized with GFP-LC3 in Irga62/2 cells. These results indicate that IFNc cannot prevent C. trachomatis development in cells lacking Irga6. Thus, our data suggest a critical role for Irga6 in provoking anti-chlamydial effects. In contrast, despite their noticeable association with bacterial inclusions, Irgd, Irgm2 and Irgm3 do not play a