Proteomic analysis of porcine mesenteric lymph-nodes after Salmonella typhimurium infection

In this study we employed for the first time an in vivo approach coupled to DIGE-based proteomics to explore the response of porcine mesenteric lymph nodes (MLN) to Salmonella typhimurium infection. MLN samples were collected from four control and twelve infected pigs (at 1, 2 and 6 days post infection) for histological analysis, protein and RNA purification. Afterwards, expressed proteins were screened by differential in gel analysis and data were analyzed by bioinformatic tools to generate interaction networks, and identify enriched signaling pathways and biological annotations. S. typhimurium labeling in tissue and phagocyte infiltration were analyzed by immunohistochemistry and RNA was employed to determine the relative expression of immune-related genes by quantitative RNA analysis. The proteome response of porcine MLN to infection was associated to the induction of processes such as phagocyte infiltration, cytoskeleton remodeling and pyroptosis. Moreover, our results suggest that S. typhimurium antigens are cross-presented via MHC-I in a proteasome-dependent manner in porcine MLN. Since pathogen burden in tissue was noticeably reduced at the end of the time course, we infer that host innate and adaptive immunity act in association in MLN to control S. typhimurium dissemination in swine infections.