Colonic interleukin-22 protects intestinal mucosal barrier and microbiota abundance in severe acute pancreatitis

Abstract

Intestinal barrier dysfunction plays a critical role in the pathophysiology of many diseases including severe acute pancreatitis (SAP). Interleukin-22 (IL-22) is a critical regulator of intestinal epithelial homeostasis. However, the mechanism, origin site, and characteristics of IL-22 in the intestinal barrier dysfunction remains elusive. Studies were conducted in patients with SAP and SAP mice model. SAP mice model was induced by intraductal infusion of 5% taurocholic acid. The level and source of IL-22 were analyzed by flow cytometry. The effect of IL-22 in SAP-associated intestinal injury were examined through knockout of IL-22 (IL-22^-/- ) or administration of recombinant IL-22 (rIL-22). IL-22 increased in the early phase of SAP but declined more quickly than that of proinflammatory cytokines, such as IL-6 and TNF-α. CD177⁺ neutrophils contributed to IL-22 expression in SAP. IL-22 was activated in the colon rather than the small intestine during SAP. Deletion of IL-22 worse the severity of colonic injury, whereas administration of rIL-22 reduced colonic injury. Mechanistically, IL-22 ameliorates the intestinal barrier dysfunction in SAP through decreasing colonic mucosal permeability, upregulation of E-cadherin and ZO-1 expression, activation of pSTAT3/Reg3 pathway and restoration of fecal microbiota abundance. This study revealing that early decreased colonic IL-22 aggravates intestinal mucosal barrier dysfunction and microbiota dysbiosis in SAP. Colonic IL-22 is likely a promising treating target in the early phase of SAP management. Research in context Evidence before this study Intestinal barrier dysfunction plays a critical role in the pathophysiology of severe acute pancreatitis (SAP). Interleukin-22 (IL-22) is a critical regulator of intestinal epithelial homeostasis. However, the mechanism, origin site and characteristics of IL-22 in the intestinal barrier dysfunction remains elusive. Added value of this study Firstly, we determined the dynamic expression profile of IL-22 in SAP and found that IL-22 was mostly activated in the pancreas and colon and decreased earlier than proinflammatory cytokines. CD177⁺ neutrophils contributed to IL-22 expression in SAP. Furthermore, we found that IL-22 ameliorates intestinal barrier dysfunction in SAP through decreasing colonic mucosal permeability, upregulation of E-cadherin and ZO-1 expression, activation of pSTAT3/Reg3 pathway and restoration of fecal microbiota abundance. Implications of all the available evidence This study highlights the role of colonic injury and colonic IL-22 in SAP. IL-22 is likely a promising treating target in the early phase of SAP management.

Keywords: CD177; acute pancreatitis; colonic injury; interleukin-22; intestinal barrier dysfunction; microbiota.