DGA ameliorates severe acute pancreatitis through modulating macrophage pyroptosis

Abstract

Severe acute pancreatitis (SAP) is an inflammatory disease with varying severity, ranging from mild local inflammation to severe systemic disease, with a high incidence rate and mortality. Current drug treatments are not ideal. Therefore, safer and more effective therapeutic drugs are urgently needed. 7α,14β-dihydroxy-ent-kaur-17-dimethylamino-3,15-dione DGA, a diterpenoid compound derivatized from glaucocalyxin A, exhibits anti-inflammatory activity. In this study, we demonstrated the therapeutic potential of DGA against SAP and elucidated the underlying mechanisms. Treatment with DGA markedly (1) inhibited death of RAW264.7 and J774a.1 cells induced by Nigericin and lipopolysaccharide, (2) alleviated edema, acinar cell vacuolation, necrosis, and inflammatory cell infiltration of pancreatic tissue in mice, and (3) inhibited the activity of serum lipase and the secretion of inflammatory factor IL-1β. DGA significantly reduced the protein expression of IL-1β and NLRP3 and inhibited the phosphorylation of NF-κB. However, DGA exhibited no inhibitory effect on the expression of caspase-1, gasdermin D (GSDMD), NF-κB, TNF-α, or apoptosis-associated speck-like protein (ASC) and on the cleavage of caspase-1 or GSDMD. Molecular docking simulation confirmed that DGA can bind to TLR4 and IL-1 receptor. In conclusion, DGA may effectively alleviate the symptoms of SAP in mice and macrophages by inhibiting the binding of TLR4 and IL-1 receptor to their ligands; therefore, DGA is a promising drug candidate for the treatment of patients with SAP.

Keywords: DGA; IL-1 receptor; Macrophage; Pyroptosis; Severe acute pancreatitis; TLR4.