YopP from Yersinia enterocolitica targets surface N-Glycans to modulate nitric oxide production in macrophage.

Yersinia enterocolitica outer protein P (YopP), a key virulence factor, is known to modulate the early host immune response. This study investigated the interaction between YopP and N-glycans on peritoneal macrophages, as well as the subsequent effects on nitric oxide (NO) production. Our findings show that YopP is released into the supernatants of Yersinia enterocolitica-infected macrophages cultures and that Yops bind to the cell surface. We further demonstrate that both YopP and N-glycans contribute to Yops release, and that Yops binding to the macrophage surface is glycan-dependent. Notably, the removal of N-glycans from surface macrophages significantly reduced NO production in vitro. Under these conditions, YopP exhibited a dual function: it suppressed NO production in non-deglycosylated macrophages but enhanced it in N-glycan-deficient macrophages, underscoring the critical role of N-glycans in the regulatory activity of YopP. Unexpectedly, the inhibitory effect of YopP on NO was found to be sialic-acid dependent and was reversed by lactose addition. In vivo experiments further confirmed the importance of N-glycans in YopP-mediated regulation of NO in infected mice. Furthermore, our findings indicate that necroptosis plays a role in YopP-induced cell death, which may, facilitate the extracellular release of Yops. In summary, this study demonstrates that YopP modulates the early immune response through a previously unrecognized mechanism involving its interaction with macrophages N-glycans. These findings reveal a complex interplay between Y. enterocolitica and its host, offering new insights into the mechanisms underlying infection.