Lipid metabolism of apoptotic vesicles accelerates cutaneous wound healing by modulating macrophage function

The application of apoptotic extracellular vesicles (ApoEVs) derived from stem cell in skin wound healing has garnered significant attention. In recent decades, scholars have shown that extracellular vesicles (EVs) established intercellular communication by carrying proteins or microRNAs, the role of lipids in EVs in wound healing has yet to be clarified. Here, we focus on the key role of group X secretory phospholipase A2 (sPLA2-X) in lipid metabolism. Specifically, sPLA2-X significantly increased the production of the anti-inflammatory lipid mediators, resolvin D5 (RvD5), by hydrolyzing phospholipids in ApoEVs. This change not only promoted the uptake of ApoEVs by macrophages, but also effectively inhibited the expression of tumor necrosis factor-alpha (TNF-α) in macrophages, promoting the healing of skin wounds. In summary, this study contributes to our understanding of the mechanisms by which ApoEVs support skin defect repair and offers a potential theoretical approach for using ApoEVs in skin wound treatment. With further research and optimization, it is expected that more efficient and secure ApoEVs-based treatment strategies will be developed, bringing new breakthroughs in clinical treatment of skin injuries and related diseases.

DHA, RvD1, RvD5, and MaR1 reduce human coronary arteries contractions induced by PGE2

In patients with coronary artery disease (CAD), plasma levels of pro-inflammatory lipid mediators such as PGE₂ and TxA₂ are increased. They could increase vascular contraction while EPA and DHA could reduce it. Studies have been mostly conducted on animal vessels. Therefore, the aim of the study was to investigate if EPA, DHA, and DHA-derived metabolites: RvD1, RvD5 and MaR1 can modulate contraction of human coronary arteries (HCA) induced by PGE₂ or TxA₂ stable analogue (U46619). DHA and EPA relaxed HCA pre-contracted with PGE₂. 18 h-incubation with DHA but not EPA reduced the PGE₂-induced contractions. Pre-incubation with RvD1, RvD5 and MaR1 reduced the PGE₂-induced contractions. Indomethacin did not significantly modify the PGE₂ responses. L-NOARG (inhibitor of nitric oxide synthase), reduced only the PGE₂-induced contractions in RvD1-treated rings. Finally, FPR2/ALX, GPR32 and LGR6 receptors are detected in HCA by immunofluorescence. Our results indicate that DHA and its metabolites could be beneficial for HCA blood flow and could be a therapeutic perspective for patients with CAD.

B10 cells promote pro-resolving macrophage function through direct cell-cell contact and IL-10 secretion in Raw 264.7 cells

It is well known that regulatory B cells (Breg), especially IL-10-producing regulatory cells (B10), play an important role in immune regulation during inflammatory and infectious diseases. Although it has been revealed that the immune regulatory function of B10 can be exerted through cognate cell-cell contact with T cells, more research is needed to delineate its impact on other key cellular immune components within the immune microenvironment. In this study, we evaluated the effect of B10 on the phenotypic change of macrophages and their pro-resolving functional activities using various co-culture systems. The roles of cell-cell contact and the IL-10 secretion by B10 on macrophage differentiation and function were determined. Splenocytes-derived B10 cells from wild-type (WT) or IL-10 knockout (KO) mice were co-cultured with RAW 264.7 cells in the presence or absence of trans-well inserts. Macrophage polarization, programmed cell death 1 (PD-1) expression, production of specialized pro-resolving mediators (SPMs), and phagocytic activity were evaluated. The results showed that direct B10-macrophage co-culture enhanced the macrophage polarization towards pro-resolving phenotype and their PD-1 expression, which was diminished when the cultured B10 and macrophages were separated by trans-well inserts, or when B cells from IL-10 KO mice were used for the co-culture. In addition, B10 was found to promote the release of specific SPM (RvD5) and phagocytic activity by macrophages after co-culture. These effects were compromised in trans-well co-culture or co-cultures with IL-10-deficient B cells. Our results suggest that B10 promotes pro-resolving macrophage differentiation and function through direct cell-cell contact and IL-10 secretion.