Fig. 6: Metrnl rejuvenates aged muscle regeneration through macrophage-derived TNF-induced FAP apoptosis. | Nature Communications

Fig. 6: Metrnl rejuvenates aged muscle regeneration through macrophage-derived TNF-induced FAP apoptosis.

From: Meteorin-like is an injectable peptide that can enhance regeneration in aged muscle through immune-driven fibro/adipogenic progenitor signaling

Fig. 6: Metrnl rejuvenates aged muscle regeneration through macrophage-derived TNF-induced FAP apoptosis.The alternative text for this image may have been generated using AI.

a Graphical representation of the experimental design for b–d. b FACS-sorted cells Sca1+ FAPs were collected and mRNA analyzed by RT-qPCR. Genes are shown relative to 18 s which remained unchanged between biological groups (n = 6 animals/group); one-way ANOVA was used with Fisher’s LSD post hoc analysis. c FACS-sorted CD45+, CD11b+ cells were collected from 3 days PI mice and cultured for 36 h to allow cytokine secretion into culture media (n = 3 animals/group). Culture media was then subjected to ELISA analysis for TNF concentration; one-way ANOVA was used with Fisher’s LSD post hoc analysis. d Sca1+ cells from 7 days post injury were collected by and stained with AnnexinV and analyzed by flow cytometry to quantify apoptotic cell percentage (n = 3/group); one-way ANOVA was used with Fisher’s LSD post hoc analysis. e Schematic representation of ex vivo culture system using conditioned media collected from BMDM-differentiated M0 macrophages from young and old mice. This conditioned media was then used to culture Sca1+ FAPs isolated by FACS from young and old muscle. This allowed the separate treatment of M0 macrophages with rMETRL and treatment of FAPs with Etanercept. f mRNA from e analyzed by RT-qPCR (n = 6/group); one-way ANOVA was used with Fisher’s LSD post hoc analysis. g schematic representation for in vivo rMETRNL treatment combined with TNF inhibitor experiment. h Representative frequency distribution and i summary data for flow cytometry of AnnexinV gated on Sca1+ FAPs at 5 days post BaCl2 injury; (n = 5 mice/group); one-way ANOVA was used with Fisher’s LSD post hoc analysis. j Representative micrographs and k summary analysis of Sirius Red staining of collagen from tibialis anterior muscles 5 days follow BaCl2 injury (n = 6 old, 10 rMetrnl, 7 Etanercept muscle sections analyzed representing five animals/group); one-way ANOVA was used with Fisher’s LSD post hoc analysis. p value is indicated with connecting line between comparison groups. Source Data are provided as a source data file. Data are presented as mean values ±  SEM. Graphics created with BioRender.com.

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