Abstract

Severe acute pancreatitis (SAP) is often associated with pulmonary inflammation leading to acute lung injury. Daphnetin, a natural coumarin derivative, has been reported to exert anti-inflammatory effects. Here, we explored the effect and possible mechanism of daphnetin in a mouse model of SAP-associated lung injury induced by an intraperitoneal injection of l-arginine. The severity of pancreatic and lung injury is determined by histology and its score. Immunostaining of inflammatory and apoptotic cells was used to demonstrate lung tissue inflammation and apoptosis; ELISA analysis of serum and tissue cytokine levels; and western blotting and immunohistochemical staining for the activated Janus kinase 2 (JAK2)–signal transducer and activator of transcription protein 3 (STAT3) signalling pathway in lung tissues. Daphnetin pretreatment significantly reduced SAP-induced pancreatic and lung tissue damage, reduced interleukin-6 and tumour necrosis factor-α concentrations in both serum and lung tissues, reduced serum amylase and myeloperoxidase activities, and reduced macrophage (CD11b) and neutrophil (Ly6G) infiltration and cell apoptosis in the lung tissue. Moreover, SAP-induced phosphorylation of JAK2 and STAT3 in the lung tissue was also significantly diminished by the daphnetin pretreatment. These results indicated that daphnetin reduces SAP-associated lung tissue damage, likely by inhibiting the activation of JAK2–STAT3 signalling.

Highlights

  • Severe acute pancreatitis (SAP) is often associated with pulmonary inflammation leading to acute lung injury

  • Increases in serum and tissue concentrations of the cytokines tumour necrosis factor-α (TNF-α) and IL-6 indicate localized and/or systemic inflammatory responses. Consistent with this finding, TNF-α (Fig. 1H) and IL-6 (Fig. 1I) levels were markedly increased in the SAP group compared with the CON and daphnetin alone (DAP) groups, but the levels were significantly lower in the SAP + DAP group

  • While previous studies have shown that daphnetin exerts a range of anti-inflammatory effects on acute liver f­ailure[26], experimental c­ olitis[27], and e­ ncephalomyelitis[28], little is known about the precise molecular mechanisms that mediate the beneficial effects of daphnetin

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Summary

Introduction

Severe acute pancreatitis (SAP) is often associated with pulmonary inflammation leading to acute lung injury. SAP induces the production of pro-inflammatory mediators, including chemokines and cytokines such as interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α), and increases the tissue infiltration and activation of macrophages (CD11b) and neutrophils (Ly6G), leading to pancreatic tissue ­necrosis[5,6]. Daphnetin has been suggested to protect rats from acute pancreatitis induced by sodium t­aurocholate[19] and to exert an anti-inflammatory effect on an endotoxin-induced model of lung i­njury[20]. It alleviates acute liver failure by inhibiting NLRP3, MAPK and NF-κB20. These observations suggest that daphnetin may be useful for the treatment of PALI

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