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Background Cysteinyl leukotrienes (CysLTs) are potent prophlogistic mediators in asthmatic patients; however, inhibition of CysLT receptor 1 is not a consistently effective treatment, suggesting additional regulatory mechanisms. Other cysteinyl-containing lipid mediators (LMs) derived from docosahexaenoic acid, namely maresin conjugates in tissue regeneration (MCTRs), were recently discovered. Therefore their production and actions in the lung are of considerable interest. Objective We sought to determine MCTR production, bioactions, and mechanisms in the human lung and in patients with experimental allergic airway inflammation. Methods LM metabololipidomic profiling of the lung was performed by using liquid chromatography with tandem mass spectrometry. Donor-derived human precision-cut lung slices were exposed to leukotriene (LT) D4, MCTRs, or both before determination of airway contraction. The actions of exogenous MCTRs on murine allergic host responses were determined in the setting of ovalbumin- and house dust mite–induced lung inflammation. Results Lipidomic profiling showed that the most abundant cysteinyl LMs in healthy human lungs were MCTRs, whereas CysLTs were most prevalent in patients with disease. MCTRs blocked LTD4-initiated airway contraction in human precision-cut lung slices. In mouse allergic lung inflammation MCTRs were present with temporally regulated production. With ovalbumin-induced inflammation, MCTR1 was most potent for promoting resolution of eosinophils, and MCTR3 potently decreased airway hyperreactivity to methacholine, bronchoalveolar lavage fluid albumin, and serum IgE levels. MCTR1 and MCTR3 inhibited lung eosinophilia after house dust mite–induced inflammation. Conclusion These results identified lung MCTRs that blocked human LTD4-induced airway contraction and promoted resolution of murine allergic airway responses when added exogenously. Together, these findings uncover proresolving mechanisms for lung responses that can be disrupted in patients with disease.

Changes in the intestinal lymphatic vascular system, such as lymphatic obstruction, are characteristic features of inflammatory bowel diseases. The lymphatic vasculature forms a conduit to enable resolution of inflammation; this process is driven by specialized endogenous proresolving mediators (SPMs). To evaluate contributions of lymphatic obstruction to intestinal inflammation and to study profiles of SPMs, we generated a novel animal model of lymphatic obstruction using African green monkeys. Follow-up studies were performed at 7, 21, and 61 days. Inflammation was determined by histology. Luminex assays were performed to evaluate chemokine and cytokine levels. In addition, lipid mediator metabololipidomic profiling was performed to identify SPMs. After 7 days, lymphatic obstruction resulted in a localized inflammatory state, paralleled by an increase in inflammatory chemokines and cytokines, which were found to be up-regulated after 7 days but returned to baseline after 21 and 61 days. At the same time, a distinct pattern of SPMs was profiled, with an increase for D-series resolvins, protectins, maresins, and lipoxins at 61 days. These results indicate that intestinal lymphatic obstruction can lead to an acute inflammatory state, accompanied by an increase in proinflammatory mediators, followed by a phase of resolution, paralleled by an increase and decrease of respective SPMs.

Resolvin conjugates in tissue regeneration (RCTRs) are new chemical signals that accelerate resolution of inflammation, infection, and tissue regeneration. Herein, using liquid chromatography–tandem mass spectrometry–based metabololipidomics, we identified RCTRs in human spleen, lymph node, bone marrow, and brain. In human spleen incubated with Staphylococcus aureus , endogenous RCTRs were increased along with conversion of deuterium-labeled docosahexaenoic acid, conferring pathway activation. Physical and biological properties of endogenous RCTRs were matched with those prepared by total organic synthesis. The complete stereochemical assignment of bioactive RCTR1 is 8 R -glutathionyl-7 S ,17 S -dihydroxy-4 Z ,9 E ,11 E ,13 Z ,15 E ,19 Z -docosahexaenoic acid, RCTR2 is 8 R -cysteinylglycinyl-7 S ,17 S -dihydroxy-4 Z ,9 E ,11 E ,13 Z ,15 E ,19 Z -docosahexaenoic acid, and RCTR3 is 8 R -cysteinyl-7 S ,17 S -dihydroxy-4 Z ,9 E ,11 E ,13 Z ,15 E ,19 Z -docosahexaenoic acid. These stereochemically defined RCTRs stimulated human macrophage phagocytosis, efferocytosis, and planaria tissue generation. Proteome profiling demonstrated that RCTRs regulated both proinflammatory and anti-inflammatory cytokines with human macrophages. In microfluidic chambers, the three RCTRs limited human polymorphonuclear cell migration. In hind-limb ischemia-reperfusion–initiated organ injury, both RCTR2 and RCTR3 reduced polymorphonuclear cell infiltration into lungs. In infectious peritonitis, RCTR1 shortened the resolution intervals. Each RCTR (1 nmol/L) accelerated planaria tissue regeneration by approximately 0.5 days, with direct comparison to both maresin and protectin CTRs. Together, these results identify a new bioactive RCTR (ie, RCTR3) in human tissues and establish the complete stereochemistry and rank-order potencies of three RCTRs in vivo . Moreover, RCTR1, RCTR2, and RCTR3 each exert potent anti-inflammatory and proresolving actions with human leukocytes.

Fatty acid-derived eicosanoids and N-acylethanolamines (NAE) are important bioactive lipid mediators involved in numerous biological processes including cell signaling and disease progression. To facilitate research on these lipid mediators, we have developed a targeted high-throughput mass spectrometric based methodology to monitor and quantitate both eicosanoids and NAEs, and can be analyzed separately or together in series. Each methodology utilizes scheduled multiple reaction monitoring (sMRM) pairs in conjunction with a 25 min reverse-phase HPLC separation. The eicosanoid methodology monitors 141 unique metabolites and quantitative amounts can be determined for over 100 of these metabolites against standards. The analysis covers eicosanoids generated from cycloxygenase, lipoxygenase, cytochrome P450 enzymes, and those generated from non-enzymatic pathways. The NAE analysis monitors 36 metabolites and quantitative amounts can be determined for 33 of these metabolites against standards. The NAE method contains metabolites derived from saturated fatty acids, unsaturated fatty acids, and eicosanoids. The lower limit of detection for eicosanoids ranges from 0.1pg to 1pg, while NAEs ranges from 0.1pg to 1000pg. The rationale and design of the methodology is discussed.