Cross-regulation of innate response in human PBMC by an enveloped RNA virus and LPS (67.11)

Abstract

Abstract The innate response to polymicrobial infections and their pathways are poorly understood. In this work, we used Sindbis virus (SIN), an enveloped RNA virus and LPS as inducers of innate response. PBMC from healthy volunteers were exposed to SIN Toto 1101, in the presence and absence of E.coli LPS. We observed absence of new virus release, SIN/GFP reporter expression and viral RNA synthesis suggesting poor replication of SIN in human PBMC. However, significant lymphocyte activation, cytokine and chemokine release were seen upon exposure of PBMC to SIN. Analysis of lymphocyte activation markers showed that, LPS was a better inducer of CD69 expression in CD4, CD8, and CD19 lymphocytes than SIN. Increased secretion of IL-12p40, IL-1β, TNF-α, IL-6, IL-18, IL-10, IL-8, RANTES, MCP-1, MIP1-α and MIP1-β was induced by LPS whereas, SIN induced IL-6, IFN-α, MCP-1, MIP1-α, MIP1-β, I-TAC and IP-10 secretion. SIN downregulated LPS induced IL-12p40 secretion, whereas LPS inhibited virus induced IFN-α and IP-10. SIN also suppressed both the spontaneous and LPS induced secretion of IFN-α, IL-17, IL-13 and SLC from PBMC. To analyze involvement of specific PBMC subsets and associated signaling events, ELISPOT and phosphoflow are used. The absence and presence of antagonism between SIN and LPS for lymphocyte activation and secretion of select cytokines and chemokines may help in understanding pathogenesis of mixed infections, and find applications in vaccine development and virotherapy.