Project description:We sought to characterize pulmonary interstitial macrophage (IM) origin, subsets, and transcriptomic profiles during homeostasis and lipopolysaccharide (LPS) induced acute lung inflammation. During homeostasis, we used three complementary methods: spectral flow cytometry, single-cell RNA-sequencing, and gene regulatory network enrichment to demonstrate that IMs can be divided into two core subsets distinguished by surface and transcriptional expression of folate receptor β (Folr2/FRβ). Within FRβ+ IMs we identified a subpopulation marked by co-expression of LYVE1. During acute LPS-induced inflammation, lung IM numbers expand. Lineage tracing revealed IM expansion was due to recruitment of monocyte-derived IMs. At the peak of inflammation, recruited IMs were comprised of two unique subsets defined by expression of genes associated with interferon signaling and glycolytic pathways. As recruited IMs matured, they adopted the overall transcriptional state of FRβ- resident IMs but retained expression in several origin-specific genes. FRβ+ IMs were of near-pure resident origin.
Project description:In this study we demonstrate that the lung mononuclear phagocyte system comprises three interstitial macrophages (IMs), as well as alveolar macrophages (AMs), dendritic cells and few extravascular monocytes. Through cell sorting and RNAseq analysis we were able to identify transcriptional similarities and differences between the three pulmonary IM subtypes, with reference to the more well-characterized alveolar macrophage
Project description:Macrophage activation syndrome (MAS) is a life-threatening cytokine storm syndrome complicating systemic juvenile idiopathic arthritis (SJIA) and driven by IFN-gamma. SJIA and MAS are also associated with an unexplained emerging inflammatory lung disease (SJIA-LD), with our recent work supporting pulmonary activation of IFN-gamma pathways as a pathologic link between SJIA-LD and MAS. Our objective was to mechanistically define the novel observation of pulmonary inflammation in the TLR9 mouse model of MAS. In acute MAS, lungs exhibit mild but diffuse CD4-predominant, perivascular interstitial inflammation with elevated IFN-gamma, IFN-induced chemokines, and alveolar macrophage expression of IFN-gamma-induced genes. Single-cell RNA-sequencing confirmed IFN-driven transcriptional changes across immune and parenchymal lung cell types. Resolution of MAS was associated with increased alveolar macrophage and interstitial lymphocytic infiltration. alveolar macrophage microarrays confirmed IFN-gamma-induced proinflammatory polarization during acute MAS, which switches towards an anti-inflammatory phenotype during MAS resolution. Interestingly, recurrent MAS led to increased alveolar inflammation and lung injury, and reset alveolar macrophagepolarization towards a proinflammatory state. Furthermore, in mice bearing macrophages insensitive to IFN-gamma, both systemic feature of MAS and pulmonary inflammation were attenuated. These findings demonstrate that experimental MAS induces IFN-gamma-driven pulmonary inflammation replicating key features of SJIA-LD, and provides a model system for testing novel treatments directed towards SJIA-LD.
Project description:Schistosomiasis, a prevalent cause of pulmonary hypertension (PH) globally, triggers type 2 inflammation, with interstitial macrophages (IMs) derived from monocytes playing a crucial role. These IMs produce thrombospondin-1 (TSP-1), activating TGF-β and driving PH pathology. Two distinct IM subpopulations were identified: resident FOLR2+ IMs expressing monocyte recruitment factors, and recruited CCR2+ IMs expressing TSP-1. Upon exposure to Schistosoma, the CCR2+ subpopulation expanded. Flow cytometry and single-cell RNA sequencing confirmed these findings, revealing crosstalk between IM subpopulations. The resident FOLR2+ IMs increased expression of monocyte recruitment ligands, while the recruited CCR2+ IMs expressed elevated TSP-1, activating TGF-β and contributing to PH. This study provides insights into the complex interplay of IM subpopulations in Schistosoma-induced PH, shedding light on potential therapeutic targets for this global health concern.
Project description:Muscle injury was elicited by cardiotoxin injection into the tibialis anterior muscle. Macrophages were isolated 2 days post-injury from the regenerating muscle. We used microarray to obtain global gene expression data of muscle-derived tissue macrophage subsets. Tissue macrophages were collected from regenerating muscle samples of three animals, Ly6C+ F4/80low and Ly6C- F4/80high macrophage subsets were sorted. The global gene expression patterns of distinct macrophage subsets were analyzed on Affymetrix microarrays.
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:Idiopathic pulmonary fibrosis (IPF) and non-specific interstitial pneumonia (NSIP) are the 2 most common forms of idiopathic interstitial pneumonia. Response to therapy and prognosis are remarkably different. The clinical-radiographic distinction between IPF and NSIP may be challenging. We sought to investigate the gene expression profile of IPF vs. NSIP We used microarray to identifiy the gene expression profiles in patients with IPF and NSIP, mixed IPF/NSIP histologic pattern and normal controls.