Chlamydia muridarum INDUCE THE EXPRESSION OF CO-INHIBITORY MOLECULES ON IMMUNE CELLS

OLIVERA, CAROLINA; GODOY, GLORIA J.; SALAZAR, FLORENCIA C.; PAIRA, DANIELA A.; MOTRICH, RUBEN D.; RIVERO, VIRGINIA E.

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias.; 2017

Chlamydia trachomatis is the most commonly reported agent of sexually transmitted bacterial infections worldwide. This pathogen frequently leads to long-term persistent subclinical infections, both in male and female. This is in part due to certain mechanisms, not yet fully elucidated, that suppress the immune response to the pathogen. Recently, the role of co-inhibitory pathways in some chronic infections has been studied, and reports suggested that the overexpression of co-inhibitory molecules would be related to pathogen persistence. In the present work we aimed to evaluate the expression profile of co-inhibitory molecules using an ?in vitro? model with Chlamydia muridarum (Cm) stimulation. For that purpose, splenocytes from C57BL/6 and NOD mice were in vitro stimulated for 24-48 h with inactivated Chlamydia Elementary Bodies at different bacteria/cell ratios. After that, PD-L1 and PD1 expression was determined by flow citometry in different cell subpopulations. A significant and dose dependent increase in the percentage of PD-L1+CD20+ lymphocytes was found after Cm stimulation when compared with non-stimulated cells (P <0.01). Not only major percentages but also higher mean fluorescence intensity for PD-L1 were observed in B lymphocytes. Cm stimulation also induced higher percentages of CD4+PD-L1+ and CD8+PD-L1+ T lymphocytes, although in minor proportions when compared with B lymphocytes. Non-significant changes were observed in CD11b+PD-L1+ and CD11c+PD-L1+ cell populations. The expression of PD1 showed a similar pattern to those observed for PD-L1. Moreover, although B and T lymphocytes from C57BL/6 and NOD mice showed PD-L1 overexpression, the NOD strain showed a more pronounced response after Cm stimulation. Our results demonstrate that Chlamydia is able to induce the expression of co-inhibitory molecules mainly in B lymphocytes, possibly attenuating the immune response and favoring chronic and persistence infections in genital tract.