Role of myeloid cells in heterotopic ossification (HO) in a burn and incision-induced mouse model
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ABSTRACT: Despite the high frequency of musculoskeletal extremity trauma, little is known about the dynamics of the initial inflammatory response that can result in pathologic healing. Here, we assess the circulatory monocyte/macrophage recruitment to sites of pathologic extremity wound healing as seen with heterotopic ossification (HO). Using single cell transcriptome analyses at key time points, we identify distinct monocyte/macrophage subpopulations that are recruited to the site of HO formation and contribute to ectopic bone development through varied transforming growth factor-1 (Tgfb1) expression. Monocyte/macrophage specific deletion of Tgfb1 leads to altered function of macrophages and reduced HO. We further identify CD47 as a novel target for Tgfb1 regulation on monocytes/macrophages as CD47 activation leads to decreased expression of Tgfb1 in macrophages and systemic treatment with CD47 activating peptide results in attenuation of canonical TGFB1 signaling and HO. These findings elucidate the critical role of monocytes/macrophage subpopulations in aberrant wound healing and provide a novel therapeutic avenue.
Project description:Macrophages are a heterogeneous population of immune cells that play central roles in a broad range of biological processes, including the resolution of inflammation. Although diverse macrophage subpopulations have been identified, the characterization and functional specialization of certain macrophage subsets in inflamed tissues remain unclear. Here we uncovered a key role of specific macrophage subsets in tissue repair using proteomics, bioinformatics and functional analyses. We isolated two hepatic monocyte-derived macrophage subpopulations: Ly6ChiCX3CR1lo macrophages and Ly6CloCX3CR1hi macrophages during distinct phases of acute liver injury and employed label-free proteomics approach to profile the proteome of these cells. We found that the wound healing- and endocytosis-related proteins were specifically enriched in Ly6CloCX3CR1hi macrophages. Intriguingly, 12/15-lipoxygenase (Alox15), the most strongly up-regulated protein in Ly6CloCX3CR1hi macrophages, was identified as a specific marker for these macrophages. In co-culture systems, Ly6CloCX3CR1hi macrophages specifically induced hepatocyte proliferation. Furthermore, selective depletion of this population in CD11b-diphtheria toxin receptor mice significantly delayed liver repair. Overall, our studies shed light on the functional specialization of distinct macrophage subsets in the resolution of inflammation.
Project description:The objective of the study was to compare the wound macs with corresponding macs derived from peripheral blood monocytes (MDMs). Wound site macrophage (wound macs were isolated from human subjects with chronic wounds. Matching blood monocyte derived macrophages (MDM) were obtained from same subjects. Transcriptome profiling (GeneChip, Affymetrix) was performed.The expression values of genes were normalized using global scaling approach. Blood monocyte derived macrophages or human wound macrophages were isolated and transcriptome analysis was performed using affymetrix gene chip analysis. Group -1 MDMs (n=3) Mac-1 Mac-2 Mac-3 Group -2 Wound macs (n=3) Wmac-1 Wmac-2 Wmac-3
Project description:Angiopoietin-like protein 4 (Angptl4) is a matricellular protein that associates with extracellular matrix proteins, mediating complex cell-cell, and cell-matrix interactions. It has been implicated in various inflammation-associated diseases, including wound healing, but very few reports describe a direct role for Angptl4 in the immune landscape of wound microenvironment. Here, we studied whether Angptl4 regulates the immune response during wound healing. Using single-cell RNA sequencing to examine the temporal changes in the immune cell landscape of excisional wounds from wild type and Angplt4-knockout (Angplt4-/-) mice revealed that Angptl4-/- wounds had a stalled inflammatory phase. Infiltrated neutrophils remained elevated in the Angptl4-/- wounds due to an impaired monocyte to macrophage differentiation needed for clearance. The impaired monocyte differentiation was also validated in wounds using multi-color flow cytometry. Pairwise comparisons of differentially expressed genes from wound-derived and bone-marrow derived macrophages demonstrated few differences, suggesting that Angptl4 has a confined regulome. We identified interferon activated protein 202B (ifi202b) to be consistently upregulated in Angptl4-/- macrophages. . Pathway analysis further confirmed that ifi202b significantly impacted multiple gene networks involved in the cell fate of monocytes and the functions of monocyte-derived macrophages. Taken altogether, we conclude that Angptl4 orchestrates the inflammatory state, innate immune landscape, and healing process in the wound microenvironment via its transcriptional regulation on ifi202b.
Project description:We investigated the gene expression profile of monocyte-derived macrophages and microglia following spinal cord injury. Moreover, we investigated the gene expression profole of M-CSF induced macrophages and new-born derived microglia following TGFb1 treatment. monocyte-derived macrophages and microglia following spinal cord injury M-CSF induced macrophages and new-born derived microglia following TGFb1 treatment
Project description:We generated a genomic and phenotypic resource comprising genetically outbred mice in which we measured (i) quantitative differences in wound healing indicated as ear area (ii) bone marrow derived macrophage (BMDM) mRNA expression by RNA-sequencing (RNA-seq), (iii) genome-wide SNPs genotyping by low-coverage sequencing.We performed gene co-expression network analysis and we identified a network in macrophages enriched in cholesterol genes which is genetically controlled by Runx2 gene. In vivo pharmacological blockage of Fasn with cerulenin showed delayed wound healing in rats and increased macrophage recruitment to the wound.
Project description:Diabetic foot ulcer (DFU) is a serious complication of diabetes mellitus, which causes great health damage and economic burden to patients. The pathogenesis of DFU is not fully understood.We screened wound healing-related genes using bioinformatics analysis, and full-thickness skin injury mice model and cellular assays were used to explore the role of target genes in diabetic wound healing. SFRP2 was identified as a wound healing-related gene, and the expression of SFRP2 is associated with immune cell infiltration in DFU. In vivo study showed that suppression of SFRP2 delayed the wound healing process of diabetic mice, impeded angiogenesis and matrix remodeling, and increased macrophage infiltration in wound tissues. In addition, suppression of SFRP2 enhanced M1 polarization in both the early and later stage of wound healing, and decreased M2 polarization in the later stage, which impeded the transition of M1 to M2 polarization of wound healing. Moreover, suppression of SFRP2 affected the transcriptome signatures-related to inflammatory response and energy metabolism at the early stage of wound healing. Extracellular flux analysis (EFA) showed that suppression of SFRP2 decreased mitochondrial energy metabolism and increased glycolysis in injury-related macrophages. Furthermore, suppression of SFRP2 inhibited transcriptome signaturesrelated to carbohydrate metabolism, lipid metabolism and amino acid metabolism, which consists the three main components of energy metabolism of macrophages. In conclusions, SFRP2 may function as a wound healing-related gene in DFU, and suppression of SFRP2 impaired diabetic wound healing by compromising the M1-to-M2 transition of macrophages and modulating the balance between mitochondrial energy metabolism and glycolysis.
Project description:Diabetic foot ulcer (DFU) is a serious complication of diabetes mellitus, which causes great health damage and economic burden to patients. The pathogenesis of DFU is not fully understood.We screened wound healing-related genes using bioinformatics analysis, and full-thickness skin injury mice model and cellular assays were used to explore the role of target genes in diabetic wound healing. SFRP2 was identified as a wound healing-related gene, and the expression of SFRP2 is associated with immune cell infiltration in DFU. In vivo study showed that suppression of SFRP2 delayed the wound healing process of diabetic mice, impeded angiogenesis and matrix remodeling, and increased macrophage infiltration in wound tissues. In addition, suppression of SFRP2 enhanced M1 polarization in both the early and later stage of wound healing, and decreased M2 polarization in the later stage, which impeded the transition of M1 to M2 polarization of wound healing. Moreover, suppression of SFRP2 affected the transcriptome signatures-related to inflammatory response and energy metabolism at the early stage of wound healing. Extracellular flux analysis (EFA) showed that suppression of SFRP2 decreased mitochondrial energy metabolism and increased glycolysis in injury-related macrophages. Furthermore, suppression of SFRP2 inhibited transcriptome signaturesrelated to carbohydrate metabolism, lipid metabolism and amino acid metabolism, which consists the three main components of energy metabolism of macrophages. In conclusions, SFRP2 may function as a wound healing-related gene in DFU, and suppression of SFRP2 impaired diabetic wound healing by compromising the M1-to-M2 transition of macrophages and modulating the balance between mitochondrial energy metabolism and glycolysis.
Project description:Healing of the cutaneous wound requires macrophage recruitment at the sites of injury, where chemotactic migration of macrophages toward the wound is regulated by local inflammation. Recent studies suggest a positive contribution of DNA methyltransferase 1 (Dnmt1) to macrophage pro-informatory responses; however, its role in regulating macrophage motility remains unknown. In this study, myeloid-specific depletion of Dnmt1 in mice promoted cutaneous wound healing and de-suppressed the lipopolysaccharides (LPS)-inhibited macrophage motility. Dnmt1 inhibition in macrophages eliminated the LPS-stimulated changes in cellular mechanical properties in terms of elasticity and viscoelasticity. LPS increased the cellular accumulation of cholesterol in a Dnmt1-depedent manner; cholesterol content determined cellular stiffness and motility. Lipidomic analysis indicated that Dnmt1 inhibition altered the cellular lipid homeostasis, probably through down-regulating the expression of cluster of differentiation 36 CD36 (facilitating lipid influx) and up-regulating the expression of ATP-binding cassette transporter ABCA1 (mediating lipid efflux) and sterol O-acyltransferase 1 SOAT1 (also named ACAT1, catalyzing the esterification of cholesterol). Our study revealed a Dnmt1-dependent epigenetic mechanism in the control of macrophage mechanical properties and the related chemotactic motility, indicating Dnmt1 as both a marker of diseases and a potential target of therapeutic intervention for wound healing.
Project description:The aim of this experiment was to investigate the role of MIF during wound healing using BALB/C MIF null mice and in the context of reduced estrogen-associated impaired healing using ovariectomized mice (a mouse model of age-associated delayed healing). Ageing is associated with delayed cutaneous wound healing resulting from reduced estrogen levels. Macrophage migration inhibitory factor (MIF - NCBI RefSeq: NM_010798) is thought to mediate the effects of estrogen on wound healing. Gene expression was compared between wounds from ovariectomized MIF null mice and controls.