Maresin conjugates in tissue regeneration biosynthesis enzymes in human macrophages

Abstract

Macrophages are central in coordinating immune responses, tissue repair, and regeneration, with different subtypes being associated with inflammation-initiating and proresolving actions. We recently identified a family of macrophage-derived proresolving and tissue regenerative molecules coined maresin conjugates in tissue regeneration (MCTR). Herein, using lipid mediator profiling we identified MCTR in human serum, lymph nodes, and plasma and investigated MCTR biosynthetic pathways in human macrophages. With human recombinant enzymes, primary cells, and enantiomerically pure compounds we found that the synthetic maresin epoxide intermediate 13S,14S-eMaR (13S,14S-epoxy- 4Z,7Z,9E,11E,16Z,19Z-docosahexaenoic acid) was converted to MCTR1 (13R-glutathionyl, 14S-hydroxy-4Z,7Z,9E,11E,13R,14S,16Z,19Z-docosahexaenoic acid) by LTC4S and GSTM4. Incubation of human macrophages with LTC4S inhibitors blocked LTC4 and increased resolvins and lipoxins. The conversion of MCTR1 to MCTR2 (13R-cysteinylglycinyl, 14S-hydroxy-4Z,7Z,9E,11E,13R,14S,16Z,19Z-docosahexaenoic acid) was catalyzed by γ-glutamyl transferase (GGT) in human macrophages. Biosynthesis of MCTR3 was mediated by dipeptidases that cleaved the cysteinyl-glycinyl bond of MCTR2 to give 13R-cysteinyl, 14S-hydroxy-4Z,7Z,9E,11E,13R,14S,16Z,19Z-docosahexaenoic acid. Of note, both GSTM4 and GGT enzymes displayed higher affinity to 13S,14S-eMaR and MCTR1 compared with their classic substrates in the cysteinyl leukotriene metabolome. Together these results establish the MCTR biosynthetic pathway and provide mechanisms in tissue repair and regeneration.

Treating inflammation and infection in the 21st century: new hints from decoding resolution mediators and mechanisms

“…For complete stereochemistry of individual SPMs, see refs. 72, 104, 107.) Low‐dose aspirin triggers the 17 R and 18 R/S epimers of the Rvs (9, 53) and 17 R ‐epimer PDs (165, 166).…”

“…The resulting reflow injury is an example of acute leukocyte‐mediated tissue damage of the delicate lung tissues. When treated with just 50 ng per mouse, which is a low dose compared with current anti‐inflammatories (3, 5), each MCTR protects the organ from secondary injury (104).…”

“…We used this system on infected mice and isolated their lymphoid tissue ( e.g ., spleen), and exudates from the peritonitis were isolated, and the PD conjugates (Fig. 6A), PCTR1, PCTR2, and PCTR3, were identified as bioactive (104, 105). These novel molecules enhanced tissue regeneration in planaria and stimulated macrophage phagocytosis of bacteria (105).…”

Structural elucidation and physiologic functions of specialized pro-resolving mediators and their receptors

“…See refs. (Serhan and Petasis, 2011; Winkler et al, 2016; Aursnes et al, 2015; Tungen et al, 2014; Dalli et al, 2016b) for original reports, total organic synthesis and stereochemical assignments and the text for further details.…”

Proresolving Lipid Mediators and Receptors in Stem Cell Biology: Concise Review

“…Upon direct conjugation of GSH to 13,14‐epoxy‐maresin (an intermediate of MaR‐1 and MaR‐2 biosynthesis) by GSH transferase, also known as LTC 4 synthase, and sequential cleavage of peptide bonds by peptidases, the following maresin conjugated in tissue regeneration (MCTR) are formed: MCTR1 (13‐glutathionyl‐14‐hydroxy DHA), MCTR2 (13‐cysteinylglycinyl‐14‐hydroxy DHA), and MCTR3 (13‐cysteinyl‐14‐hydroxy DHA) . In addition, attack of GSH at the 7,8‐epoxide intermediate of RvD yields resolvin conjugate in tissue regeneration 1 (RCTR1) that is in turn cleaved into RCTR2 by γ‐glutamyltranspeptidase and into RCTR3 via peptidases .…”