Asthma is a chronic inflammatory disease that fails to resolve. Recently, a key role for type 2 innate lymphoid cells (ILC2) was linked to asthma pathogenesis; however, mechanisms for ILC2 regulation remain to be determined. Here, metabololipidomics of murine lungs identified temporal changes in endogenous maresin 1 (MaR1) during self-limited allergic inflammation. Exogenous MaR1 reduced lung inflammation, ILC2 expression of interleukin-5 and 13, and increased amphiregulin. MaR1 augmented de novo generation of regulatory T cells (Tregs), which interacted with ILC2 to markedly suppress cytokine production in a TGF-β-dependent manner. Antibody-mediated depletion of Tregs interrupted MaR1 control of ILC2 expression of IL-13 in vivo. Together, the findings uncover Tregs as potent regulators of ILC2 activation; MaR1 targets Tregs and ILC2 to restrain allergic lung inflammation, suggesting MaR1 as the basis for a new pro-resolving therapeutic approach to asthma and other chronic inflammatory diseases.

Local mediators orchestrate the host response to both sterile and infectious challenge and resolution. Recent evidence demonstrates that maresin sulfido‐conjugates actively resolve acute inflammation and promote tissue regeneration. In this report, we investigated self‐limited infectious exudates for novel bioactive chemical signals in tissue regeneration and resolution. By use of spleens from Escherichia coli infected mice, self‐resolving infectious exudates, human spleens, and blood from patients with sepsis, we identified 2 new families of potent molecules. Characterization of their physical properties and isotope tracking demonstrated that the bioactive structures contained a docosahexaenoate backbone and sulfido‐conjugated triene or tetraene double‐bond systems. Activated human phagocytes converted 17‐hydro(peroxy)‐4Z,7Z,10Z,13Z,15E,19Z‐docosahexaenoic acid to these bioactive molecules. Regeneration of injured planaria was accelerated with nanomolar amounts of 16‐glutathionyl, 17‐hydroxy‐4Z,7Z,10,12,14,19Z‐docosahexaenoic acid and 16‐cysteinylglycinyl, 17‐hydroxy‐4Z,7Z,10,12,14,19Z‐docosahexaenoic acid (Protectin sulfido‐conjugates) or 8‐glutathionyl, 7,17‐dihydroxy‐4Z,9, 11,13Z,15E,19Z‐docosahexaenoic acid and 8‐cysteinylglycinyl, 7,17‐dihydroxy‐4Z,9,11,13Z, 15E,19Z‐docosahexaenoic acid (Resolvin sulfido‐conjugates). Each protectin and resolvin sulfido‐conjugate dose dependently (0.1‐10 nM) stimulated human macrophage bacterial phagocytosis, phagolysosomal acidification, and efferocytosis. Together, these results identify 2 novel pathways and provide evidence for structural elucidation of new resolution moduli. These resolvin and protectin conjugates identified in mice and human infected tissues control host responses promoting catabasis.—Dalli, J., Ramon, S., Norris, P. C., Colas, R. A., Serhan, C. N. Novel proresolving and tissue‐regenerative resolvin and protectin sulfido‐conjugated pathways. FASEB J. 29, 2120‐2136 (2015). http://www.fasebj.org