L'immuno-modulation et l'immuno-suppression chez les grands brûlés
Burns induce an intense inflammatory activation leading to the exhaustion of patients' immune system. In turn, this phenomenon generates an immunosuppressive anti-inflammatory phase that opens the floodgates to nosocomial infections. Our laboratory has already analyzed samples of 25 patients with severe burns and has observed an alteration of monocytes, pro- and anti-inflammatory cytokine levels and functions of B cells. We hypothesize that burns lead to the hyperactivation of antigen-presenting cells (APCs) which subsequently generates an immunosuppressive state. We also propose that the inflammatory state of patients is influenced by the microbiome. Our objectives are to evaluate the immunological activation of peripheral leukocytes, APCs in particular; optimize the analysis techniques of blood microbiome and study peripheral bacterial populations in burned patients.  Our in vitro experiments reveal that, in the presence of burned patient serum, monocytes adopt a regulatory profile of inflammation; whereas B cells proliferate less and produce less IgA, IgG and IgM. Monocytes stimulate the proliferation of B cells through cellular interactions but also inhibit antibody secretion. Soluble BAFF concentration in burned patients increases 5 days post-burn and this could establish a link between monocytes and B cell deregulation. Extraction and detection techniques of bacterial DNA from blood and skin have been optimized. The amount of circulating total DNA is modulated post-burn but the amount of bacterial equivalents in the blood of burned patients is unchanged.  It is crucial to obtain a better knowledge on the activation status of the immune cells and their interactions with the microbiome. This will allow the development of novel immune therapy to correct the immune exhaustion present in burn patients.
Inflammation Immunosuppression Infection Monocyte Macrophage Lymphocyte B Microbiome Burn Inflammation Immunosuppression Infection Monocyte Macrophage B lymphocyte Microbiome Bacteria DNA