Resolvin-E1 and Lipoxin-A4 Control Pro-inflammatory PMN Functions in Diabetes

Eicosapentaenoic acid (EPA)-derived resolvin-E1 (RvE1) and aspirin-triggered lipoxins (ATL) are endogenous pro-resolving molecules in inflammation. Diabetes is characterized in part by hyperactive PMN that mediate inflammatory changes associated with diabetic complications. OBJECTIVE: The aim was to characterize RvE1 and ATL actions on PMN superoxide production in healthy and diabetic individuals. METHODS: PMN from diabetic patients (n=15) and healthy controls (n=14) were isolated. ATL (a metabolically stable analog; 15-epi-16-phenoxyparafluoro-LXA4) and RvE1 were prepared by total organic synthesis. PMN were first treated with different doses (10^-6-10^-13M) of ATLa or RvE1 and then challenged with fMLP (10^-6M) or tumor necrosis factor (TNF-α; 50ng/ml). Superoxide formation was monitored using a cytochrome c reduction assay. RESULTS: PMN from diabetic subjects generated significantly more (3-6 times) superoxide compared to healthy individuals (p<0.05) in response to fMLP or TNF-α. Treatment of healthy and diabetic PMN with ATLa or RvE1 dampened the superoxide response up to 90% in a dose-dependent manner (EC50: ATLa: 10^-10M and 10^-9M for healthy and diabetic PMN, respectively; RvE1: 10^-10M for both diabetic and healthy PMN). PMN from poorly-controlled diabetics (HbA1c>8.0%) had significantly higher superoxide generation compared to PMN from well-controlled subjects (HbA1c<7.0%; p<0.05); both ATLa and RvE1 equally dampened the superoxide release in diabetic PMN regardless of the glycemic control. Likewise, PMN from diabetics with moderate-severe periodontitis had significantly higher superoxide release compared to subjects with gingivitis-mild periodontitis (p<0.05); but the PMN response was dampened by ATLa or RvE1 regardless of the chronic periodontitis. CONCLUSIONS: RvE1 and ATLa, two distinct lipid mediators generated from 2 different fatty acid precursors, arachidonic acid and EPA, elicit similar responses from diabetic PMN dampening their inflammatory actions. Thus, RvE1 and ATLa are potential new therapeutic options in resolving PMN-mediated inflammation and tissue injury in diabetes. Supported by USPHS Grants DE15566 and RR00533.