Overexpression of Plakophilin2 Mitigates Capillary Leak Syndrome in Severe Acute Pancreatitis by Activating the p38/MAPK Signaling Pathway.

Purpose: Capillary leak syndrome (CLS) is an intermediary phase between severe acute pancreatitis (SAP) and multiple organ failure. As a result, CLS is of clinical importance for enhancing the prognosis of SAP. Plakophilin2 (PKP2), an essential constituent of desmosomes, plays a critical role in promoting connections between epithelial cells. However, the function and mechanism of PKP2 in CLS in SAP are not clear at present.

Methods: We detected the expression of PKP2 in mice pancreatic tissue by transcriptome sequencing and bioinformatics analysis. PKP2 was overexpressed and knocked down to assess its influence on cell permeability, the cytoskeleton, tight junction molecules, cell adhesion junction molecules, and associated pathways.

Results: PKP2 expression was increased in the pancreatic tissues of SAP mice and human umbilical vein endothelial cells (HUVECs) after lipopolysaccharide (LPS) stimulation. PKP2 overexpression not only reduced endothelial cell permeability but also improved cytoskeleton relaxation in response to acute inflammatory stimulation. PKP2 overexpression increased levels of ZO-1, occludin, claudin1, β-catenin, and connexin43. The overexpression of PKP2 in LPS-induced HUVECs counteracted the inhibitory effect of SB203580 (a p38/MAPK signaling pathway inhibitor) on the p38/MAPK signaling pathway, thereby restoring the levels of ZO-1, β-catenin, and claudin1. Additionally, PKP2 suppression eliminated the enhanced levels of ZO-1, β-catenin, occludin, and claudin1 induced by dehydrocorydaline. We predicted that the upstream transcription factor PPARγregulates PKP2 expression, and our findings demonstrate that the PPARγactivator rosiglitazone significantly upregulates PKP2, whereas its antagonist GW9662 down-regulates PKP2. Administration of rosiglitazone significantly reduced the increase in HUVECs permeability stimulated by LPS. Conversely, PKP2 overexpression counteracted the GW9662-induced reduction in ZO-1, phosphorylated p38/p38, and claudin1.

Conclusion: The activation of the p38/MAPK signaling pathway by PKP2 mitigates CLS in SAP. PPARγactivator rosiglitazone can up-regulate PKP2. Overall, directing efforts toward PKP2 could prove to be a feasible treatment approach for effectively managing CLS in SAP.