Yop effector proteins from Yersinia pseudotuberculosis impair dendritic cell activation

Abstract

Yersinia pseudotuberculosis can inhibit multiple stages of dendritic cell (DC) function, including antigen uptake and degradation, maturation, and subsequent T-cell activation. In this study, we analyzed whether Y. pseudotuberculosis infection and Yop effector proteins play a role in the maturation and immunostimulatory capacity of DCs originating from differentiated bone marrow precursors from BALB/c or C57BL/6 mice. We found that Y. pseudotuberculosis reduces major histocompatibility complex (MHC) class II, CD80 and CD86 expression in both strains of mice, although the bacteria had a greater effect in BALB/c mice. We observed that YopE could interfere with the expression of maturation markers, which indicates a possible role for YopE in the inhibition of DC maturation. Infection by Y. pseudotuberculosis leads to a decrease in the immunostimulatory capacity of DCs, with T-cell proliferation significantly reduced on day 4 of co-culture. Stimulation of T cells by DCs infected with YopJ, YopE, and YopH mutants has a less robust effect on T-cell proliferation. The reduction in the expression of maturation markers and diminished immunostimulatory capacity of infected DCs may contribute to the ability of Y. pseudotuberculosis to evade adaptive immune responses and subsequently inhibit the host's ability to clear the infection. © 2012 Springer Science+Business Media New York.