trachomatis released from NK cell-exposed infected cells, pooled A2EN cell lysates and culture supernatants from C. trachomatis-infected cells cocultured with NK cells were compared with those cultured for the same period of time postinfection but in the absence of NK cells. The marked decrease in recoverable IFU from cells cocultured with NK92MI cells (Fig. 5; Fig. S1) suggests that these effector cells exert some degree of sterilizing effect on C. trachomatis-infected endocervical cells and that host NK cells could decrease the infectious burden during C. trachomatis infection. Surprisingly, however, we note that although efficient lysis of C. trachomatis-infected cells was observed
at 34 hpi, the observed decrease in IFU recovered was only twofold. These data suggest that C. trachomatis may be equipped with some form of escape mechanisms despite NK cell-mediated LDK378 datasheet lysis of its host cells. Infectious pathogens evade innate and adaptive host immune detection through modulation of host responses. Successful pathogens, including C. trachomatis, exert overlapping and redundant mechanisms that often include alterations in those host ligands that mediate interactions with innate and adaptive immune cells (Tortorella et al., 2000). While GW-572016 ic50 well-orchestrated, pathogen protective strategies would promote evasion of antigen nonspecific innate immunity and antigen-specific adaptive
responses, co-evolution of pathogen and host enable a balance between Alanine-glyoxylate transaminase pathogen evasion
and host protection. For C. trachomatis, we and others have shown that host cell MHC class I, Class II, and CD1d are degraded in infected cells relatively late in the pathogen’s developmental cycle (Zhong et al., 1999; : Zhong et al., 2000; : Zhong et al., 2001; Kawana et al., 2007, 2008). This occurs well after the initiation of chemokine/cytokine secretion by C. trachomatis-infected epithelial cells, which usually does not begin until 20–24 h after infection (Rasmussen et al., 1997). The latter delay may allow a window for unfettered pathogen growth and development. We have recently demonstrated that downregulation of cell surface expression of MHC class I in C. trachomatis-infected A2EN cells can be seen on infected cells and on bystander, noninfected cells in culture (Ibana et al., 2011a), which may further protect C. trachomatis pathogens from antigen-specific clearance. By harnessing our capability to assess the host epithelial cell response to C. trachomatis in both bystander-noninfected cells and C. trachomatis-infected cells, we now show that the effects on MHC class I and on MICA kinetically occur in tandem, beginning prior to 24 hpi and lasting until late in the developmental cycle. Unlike its effects on MHC class I, the effects of C. trachomatis on MICA expression include an upregulation of expression, effects that are significantly more prolonged (still rising at 42 hpi) and effects that are limited to infected cells.