Resolvin E1 reduces proinflammatory markers in human pancreatic islets in vitro

Abstract

Background: In clinical islet transplantation, inflammatory responses initiated by the transplanted islets and by the host immune system cause acute and chronic graft loss. The resolution of acute inflammation is an active process mediated by specific signals and mediators such as resolvin E1 (RvE1). We investigated the effect of RvE1 on i) the inflammatory status of human pancreatic islets, ii) islet viability and apoptosis, and iii) the instant blood-mediated inflammatory reaction (IBMIR) IN VITRO.

Methods: Pro-inflammatory cytokines and tissue factor (TF) in isolated human islets were determined by real-time RT-qPCR (mRNA levels), CBA and Gyrolab bioaffy (protein levels) after lipopolysaccaride (LPS) stimulation. Islet viability was measured using insulin secretion in a dynamic model, ADP/ATP ratio and total ATP content. Apoptosis was measured using commercial kits after stimulation with proinflammatory cytokines. To assess effect on IBMIR, human islets were mixed with non-anticoagulated, RvE1 or vehicle pretreated ABO-compatible blood in heparin-coated tubing loops.

Results: Treatment of human islets with RvE1 (500 nM) for 24 h reduced LPS-induced increase in mRNA and protein levels of selected pro-inflammatory markers (IL-8, MCP-1, and TF). RvE1 lowered the ADP/ATP ratio, but had no effect on insulin secretion. RvE1 reduced the apoptotic effect of proinflammatory cytokines. Additionally, RvE1 reduced platelet consumption and TAT complex formation during the first 5 min after islet-blood contact.

Conclusions: RvE1 suppresses proinflammatory markers and lowers the ADP/ATP ratio in human islets IN VITRO. RvE1 demonstrates anti-apoptotic effects in a proinflammatory milieu. Additionally, RvE1 has modest dampening effects on IBMIR. We conclude that RvE1 may have potential in clinical islet transplantation.