S100A9‑containing serum exosomes obtained from patients with burn injuries promote myocardial cell pyroptosis through NLRP3.

Abstract

S100 calcium-binding protein A9 (S100A9) is highly expressed in the serum exosomes of patients with burn injuries. The present study aimed to investigate the underlying mechanisms of burn injury-associated exosomes in the regulation of myocardial cell pyroptosis. Reverse transcription-quantitative PCR and western blotting were used to examine relative mRNA and protein levels. The morphology of exosomes was visualized using transmission electron microscopy. The expression levels of IL-1β and IL-18 in cells were examined using ELISA kits. Finally, cell pyroptosis was examined using flow cytometry. When AC16 cells were treated with the serum exosomes obtained from patients with burn injuries, pyroptosis was significantly promoted and the expression levels of IL-1β and IL-18 were increased. NLR family pyrin domain containing 3 (NLRP3), S100A9, caspase-1 and Gasdermin D (GSDMD)-N expression levels were also upregulated. However, these were significantly reversed by anti-S100A9 antibodies. Thereafter, CY-09, an NLRP3 inhibitor, was revealed to restore the increase in pyroptosis and IL-18, IL-1β, caspase-1, NLRP3 and GSDMD-N expression levels caused by recombinant S100A9 to be similar to the control. These findings suggested that burn injury-associated exosomes containing S100A9 can affect AC16 cell pyroptosis through NLRP3.