S100A9 Inhibition Mitigates Acute Pancreatitis by Suppressing RAGE Expression and Subsequently Ameliorating Inflammation.

Acute pancreatitis (AP) is a common acute inflammatory abdominal condition. Severe acute pancreatitis (SAP) can provoke a systemic inflammatory response and lead to multiple organ failure. The S100A9 protein, recognized as a major inflammatory biomarker, plays a significant role in both infection and inflammatory responses. Despite its known role in inflammation, the precise role of S100A9 in AP remains poorly understood. This study aimed to elucidate the potential role of S100A9 in AP and investigate the underlying mechanism. We employed a mouse model of AP and the AR42J cell line to investigate the functional role of S100A9. The effect of S100A9 on pancreatic injury and the expression of inflammatory factors (IL-6, IL-1β, and TNF-α) was assessed through targeted inhibition of S100A9 expression in the mouse model of AP. Furthermore, the modulatory effect of cerulein-induced inflammatory responses on AR42J cells was assessed after adding the S100A9 recombinant protein. In the mouse model of AP, targeted inhibition of S100A9 markedly ameliorated pancreatic injury and significantly decreased the expression levels of IL-6, IL-1β, and TNF-α. Moreover, increased levels of S100A9 were positively correlated with elevated expression of receptor for advanced glycation endproducts (RAGE) in pancreatic acinar cells. In AR42J cells, the introduction of S100A9 recombinant protein enhanced RAGE expression and exacerbated cerulein-induced inflammatory response. S100A9 inhibition significantly alleviated the pancreatic inflammatory response by downregulating RAGE expression, thereby improving AP.