Systemic inflammatory response syndrome following burns is mediated by brain natriuretic peptide/natriuretic peptide...

The aim of this study was to determine whether systemic inflammatory response syndrome (SIRS) in burn patients is mediated by the brain natriuretic peptide (BNP)/natriuretic peptide A receptor (NPRA)-induced heat shock factor 1 (HSF-1) signalling pathway. Mononuclear cells (MNCs) that were isolated from patients with burn injuries and SIRS mouse models and a RAW264.7 cell line were treated with normal serum or serum obtained from animals with burn injuries. In parallel, small hairpin RNAs (shRNAs) against BNP or NPRA were transfected in both cell types. Western blotting (WB) and enzyme-linked immunosorbent assay (ELISA) were used to detect protein expression and inflammatory factor levels, respectively. We found that interleukin (IL)-12, tumour necrosis factor (TNF)-α, C-reactive protein (CRP), and BNP levels were increased and IL-10 levels were decreased in the plasma and MNCs in vivo in the animal model of SIRS. Additionally, NPRA was upregulated, whereas HSF-1 was downregulated in monocytes in vivo. Treatment of RAW264.7 cells with burn serum or BNP induced IL-12, TNF-α, and CRP secretion as well as HSF-1 expression. Finally, silencing BNP with shRNA interrupted the effect of burn serum on RAW264.7 cells, and silencing NPRA blocked burn serum- and BNP-mediated changes in RAW264.7 cells. These results suggest that the interaction of NPRA with BNP secreted from circulatory MNCs as well as mononuclear macrophages leads to inflammation via HSF-1 during SIRS development following serious burn injury.