LXA4 actions direct fibroblast function and wound closure

Timely resolution of inflammation is crucial for normal wound healing. Resolution of inflammation is an active biological process regulated by specialized lipid mediators including the lipoxins and resolvins. Failure of resolution activity has a major negative impact on wound healing in chronic inflammatory diseases that is manifest as excess fibrosis and scarring. Lipoxins, including Lipoxin A(4) (LXA(4)), have known anti-fibrotic and anti-scarring properties. The goal of this study was to elucidate the impact of LXA(4) on fibroblast function. Mouse fibroblasts (3T3 Mus musculus Swiss) were cultured for 72 h in the presence of TGF-beta 1, to induce fibroblast activation. The impact of exogenous TGF-beta 1 (1 ng/mL) on LXA(4) receptor expression (ALX/FPR2) was determined by flow cytometry. Fibroblast proliferation was measured by bromodeoxyuridine (BrdU) labeling and migration in a scratch assay wound model. Expression of alpha-smooth muscle actin (alpha-SMA), and collagen types I and III were measured by Western blot. We observed that TGF-beta 1 up-regulates LXA(4) receptor expression, enhances fibroblast proliferation, migration and scratch wound closure. alpha-SMA levels and Collagen type I and III deposition were also enhanced. LXA(4) slowed fibroblast migration and scratch wound closure at early time points (24 h), but wound closure was equal to TGF-beta 1 alone at 48 and 72 h. LXA(4) tended to slow fibroblast proliferation at both concentrations, but had no impact on alpha-SMA or collagen production by TGF-beta 1 stimulated fibroblasts. The generalizability of the actions of resolution molecules was examined in experiments repeated with resolvin D2 (RvD2) as the agonist The activity of RvD2 mimicked the actions of LXA(4) in all assays, through an as yet unidentified receptor. The results suggest that mediators of resolution of inflammation enhance wound healing and limit fibrosis in part by modulating fibroblast function. (C) 2015 Elsevier Inc. All rights reserved.