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Protease-activated receptor 2 (PAR2) regulates inflammatory responses and lipid metabolism. However, its precise role in colitis remains unclear. Here, we aimed to investigate the function of PAR2 in high-fat diet fed mice with colitis and its potential role in autophagy. PAR2+/+ and PAR2-/- mice were fed a high-fat diet (HFD) for 7 days before colitis induction with dextran sodium sulfate. Deletion of PAR2 and a HFD significantly exacerbated colitis as shown by increased mortality, body weight loss, diarrhea or bloody stools, colon length shortening, and mucosal damage. Pro-inflammatory cytokine levels were elevated in HFD-fed PAR2-/- mice and in cells treated with the PAR2 antagonist GB83, palmitic acid (PA), and a cytokine cocktail (CC). Damaging effects of PAR2 blockage were associated with autophagy regulation by reducing the levels of YAP1, SIRT1, PGC-1α, Atg5, and LC3A/B-I/II. Additionally, mitochondrial dysfunction was demonstrated only in cells treated with GB83, PA, and CC. Reduced cell viability and greater induction of apoptosis, as shown by increased levels of cleaved caspase-9, cleaved caspase-3, and cleaved PARP, were observed in cells treated with GB83, PA, and CC but not in those treated with only PA and CC. Collectively, protective effects of PAR2 were elucidated during inflammation accompanied by high-fat environment by promoting autophagy and inhibiting apoptosis, suggesting PAR2 as a therapeutic target for inflammatory bowel disease co-occurring with metabolic syndrome.

No abstract