Resolvin D1 supports skeletal myofiber regeneration via actions on myeloid and muscle stem cells
James F. Markworth, … , Krishna Rao Maddipati, Susan V. Brooks
James F. Markworth, … , Krishna Rao Maddipati, Susan V. Brooks
Published August 4, 2020
Citation Information: JCI Insight. 2020;5(18):e137713. https://doi.org/10.1172/jci.insight.137713.
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Research Article Inflammation Muscle biology

Resolvin D1 supports skeletal myofiber regeneration via actions on myeloid and muscle stem cells

Abstract

Specialized proresolving mediators (SPMs) actively limit inflammation and expedite its resolution by modulating leukocyte recruitment and function. Here we profiled intramuscular lipid mediators via liquid chromatography-tandem mass spectrometry–based metabolipidomics following myofiber injury and investigated the potential role of SPMs in skeletal muscle inflammation and repair. Both proinflammatory eicosanoids and SPMs increased following myofiber damage induced by either intramuscular injection of barium chloride or synergist ablation–induced functional muscle overload. Daily systemic administration of the SPM resolvin D1 (RvD1) as an immunoresolvent limited the degree and duration of inflammation, enhanced regenerating myofiber growth, and improved recovery of muscle strength. RvD1 suppressed inflammatory cytokine expression, enhanced polymorphonuclear cell clearance, modulated the local muscle stem cell response, and polarized intramuscular macrophages to a more proregenerative subset. RvD1 had minimal direct impact on in vitro myogenesis but directly suppressed myokine production and stimulated macrophage phagocytosis, showing that SPMs can modulate both infiltrating myeloid and resident muscle cell populations. These data reveal the efficacy of immunoresolvents as a novel alternative to classical antiinflammatory interventions in the management of muscle injuries to modulate inflammation while stimulating tissue repair.

Authors

James F. Markworth, Lemuel A. Brown, Eunice Lim, Carolyn Floyd, Jacqueline Larouche, Jesus A. Castor-Macias, Kristoffer B. Sugg, Dylan C. Sarver, Peter C.D. Macpherson, Carol Davis, Carlos A. Aguilar, Krishna Rao Maddipati, Susan V. Brooks

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Figure 3

Resolvin D1 limits inflammation and expedites its resolution following muscle injury.

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Resolvin D1 limits inflammation and expedites its resolution following m...
(A) C57BL/6 mice received bilateral intramuscular injection of the TA muscle with 50 μL of 1.2% BaCl2 to induce myofiber injury. Mice were treated with RvD1 (100 ng) or vehicle (0.1% ethanol) via intraperitoneal (IP) injection approximately 5 minutes before muscle injury. TA cross sections were stained for PMNs (Ly6G) or monocytes/macrophages (CD68). Cell nuclei and the basal lamina were counterstained with DAPI and laminin antibody, respectively. Scale bars: 200 μm. (B) Whole-muscle mRNA expression of immune cell markers and inflammatory cytokines at 24 hours postinjury as determined by real-time quantitative reverse transcription PCR (RT-qPCR). Gene expression was normalized to Actb. (C) Mice were treated for 72 hours with daily IP injection of RvD1 (100 ng) or vehicle (0.1% ethanol) following muscle injury, and TA cross sections were stained for PMNs (Ly6G) or macrophages (CD68) at day 3 postinjury. Representative images show examples of regions of muscle not yet infiltrated by macrophages where lingering PMNs remained (top) and macrophage-rich regions largely devoid of PMNs (bottom). (D) Single cells isolated from pooled left and right TA muscles at day 3 postinjury were analyzed by flow cytometry for CD45-PE and Ly6G-FITC. Bars show the mean ± SEM of 5–10 mice per group with dots representing data from each mouse. P values were determined 2-tailed unpaired t tests.