Project description:Kidney macrophages are comprised of both monocyte-derived and tissue resident populations; however, the heterogeneity of kidney macrophages and factors that regulate their heterogeneity are poorly understood. Herein, we performed single cell RNA sequencing (scRNAseq), fate mapping, and parabiosis to define the cellular heterogeneity of kidney macrophages in healthy mice. Our data indicate that healthy mouse kidneys contain four major subsets of monocytes and two major subsets of kidney resident macrophages (KRM) including a population with enriched Ccr2 expression, suggesting monocyte origin. Surprisingly, fate mapping data using the newly developed Ms4a3Cre Rosa Stopf/f TdT model indicate that less than 50% of Ccr2+ KRM are derived from Ly6chi monocytes. Instead, we find that Ccr2 expression in KRM reflects their spatial distribution as this cell population is almost exclusively found in the kidney cortex. We also identified Cx3cr1 as a gene that governs cortex specific accumulation of Ccr2+ KRM and show that loss of Ccr2+ KRM reduces the severity of cystic kidney disease in a mouse model where cysts are mainly localized to the kidney cortex. Collectively, our data indicate that Cx3cr1 regulates KRM heterogeneity and niche-specific disease progression.
Project description:Kidney macrophages are comprised of both monocyte-derived and tissue resident populations; however, the heterogeneity of kidney macrophages and factors that regulate their heterogeneity are poorly understood. Herein, we performed single cell RNA sequencing (scRNAseq), fate mapping, and parabiosis to define the cellular heterogeneity of kidney macrophages in healthy mice. Our data indicate that healthy mouse kidneys contain four major subsets of monocytes and two major subsets of kidney resident macrophages (KRM) including a population with enriched Ccr2 expression, suggesting monocyte origin. Surprisingly, fate mapping data using the newly developed Ms4a3Cre Rosa Stopf/f TdT model indicate that less than 50% of Ccr2+ KRM are derived from Ly6chi monocytes. Instead, we find that Ccr2 expression in KRM reflects their spatial distribution as this cell population is almost exclusively found in the kidney cortex. We also identified Cx3cr1 as a gene that governs cortex specific accumulation of Ccr2+ KRM and show that loss of Ccr2+ KRM reduces the severity of cystic kidney disease in a mouse model where cysts are mainly localized to the kidney cortex. Collectively, our data indicate that Cx3cr1 regulates KRM heterogeneity and niche-specific disease progression.
Project description:LN resident macrophages lining the lymphatic sinuses play critical roles in antigen capture and presentation as well as degradation. We used microarray to examine global gene expression profiles to compare SCS and med macrophages to determine the underlying molecular basis of their differential handling of antigens. Primary SCS and med macrophages were isolated and purified from LNs by flourescence-activated cell sorting and RNA extracted, amplified and hybridized for Affymetrix analysis.
Project description:Acute kidney injury (AKI) is a major health burden in the United States. Macrophages have been shown to mediate AKI in murine models. Murine kidneys contain multiple subpopulations of kidney resident macrophages (KRM) that are transcriptionally and spatially distinct. We hypothesized the human kidney contains orthologous KRM subpopulations, both transcriptionally and spatially. We utilized kidney sections from donors diagnosed with mild to moderate AKI in order to increase the translatability of murine research to clinical settings. We used spatial transcriptomics and single cell RNA sequencing to identify five distinct human KRM subpopulations. Using the AddModuleScore function in Seurat, we were able to compare the murine KRM transcriptional profiles from pre and post-AKI to the human KRM subpopulations. As a result, we identified four orthologous to known murine KRM subpopulations. The remaining population was identified in the kidney cortex and expresses a profile similar to activate microglia, the resident macrophage population in the brain. Again, we used AddModuleScore to determine a set of marker genes that will allow for the identification of KRM subsets across species and injury.
Project description:The kidney contains a population of resident macrophages from birth that expands as it grows and forms a contiguous network throughout the tissue. Kidney resident macrophages (KRMs) are important in homeostasis and the response to acute kidney injury (AKI). While the kidney contains many microenvironments, it is unknown whether KRMs are a heterogeneous population differentiated by function and location. We combined single-cell RNA sequencing (scRNAseq), spatial transcriptomics, flow cytometry, and immunofluorescence imaging to localize, characterize, and validate KRM populations during quiescence and following 19 minutes of bilateral ischemic kidney injury. scRNAseq and spatial transcriptomics revealed seven distinct KRM subpopulations, which are organized into zones corresponding to regions of the nephron. Each subpopulation was identifiable by a unique transcriptomic signature suggesting distinct functions. Specific protein markers were identified for two clusters allowing analysis by flow cytometry or immunofluorescence imaging. Following injury, the original localization of each subpopulation is lost, either from changing locations or transcriptomic signatures. The original spatial distribution of KRMs is not fully restored for at least 28 days post-injury. The change in KRM localization confirms a long hypothesized dysregulation of the local immune system following acute injury and may explain the increased risk for chronic kidney disease.
Project description:Skeletal muscle dysfunction in survivors of pneumonia is a major cause of lasting morbidity that disproportionately affects older individuals. We found that skeletal muscle recovery was impaired in aged compared with young mice after influenza A virus-induced pneumonia. In young mice, recovery of muscle loss was associated with expansion of tissue-resident skeletal muscle macrophages and downregulation of MHC II expression, followed by a proliferation of muscle satellite cells. These findings were absent in aged mice and in mice deficient in Cx3cr1. Transcriptomic profiling of tissue-resident skeletal muscle macrophages from aged compared with young mice showed downregulation of pathways associated with phagocytosis and proteostasis, and persistent upregulation of inflammatory pathways. Consistently, skeletal muscle macrophages from aged mice failed to downregulate MHCII expression during recovery from influenza A virus induced pneumonia and showed impaired phagocytic function in vitro. Like aged animals, mice deficient in the phagocytic receptor Mertk showed no macrophage expansion, MHCII downregulation or satellite cell proliferation and failed to recover skeletal muscle function after influenza A pneumonia. Our data suggest that a loss of phagocytic function in a CX3CR1+ tissue-resident skeletal muscle macrophage population in aged mice precludes satellite cell proliferation and recovery of skeletal muscle function after influenza A pneumonia.
Project description:Macrophages are hematopoietic cells critical for innate immune defense, but also control organ homeostasis in a tissue-specific manner. Tissue-resident macrophages, therefore, provide a well-defined model to study the impact of ontogeny and microenvironment on chromatin state. Here, we profile the dynamics of four histone modifications across seven tissue-resident macrophage populations, as well as monocytes and neutrophils. We identify 12,743 macrophage-specific enhancers and establish that tissue-resident macrophages have distinct enhancer landscapes. Our work suggests that a combination of tissue and lineage-specific transcription factors form the regulatory networks controlling chromatin specification in tissue-resident macrophages. The environment has the capacity to alter the chromatin landscape of macrophages derived from transplanted adult bone marrow in vivo and even differentiated macrophages are reprogrammed when transferred into a new tissue. Altogether, these data provide a comprehensive view of macrophage regulation and highlight the importance of microenvironment along with pioneer factors in orchestrating macrophage identity and plasticity. 7 tissue-resident macrophage populations were isolated, as well as monocytes and neutrophils, and transcriptome analysis was performed. Experiment was done in duplicates.
Project description:Background: Immune cell populations within the intestinal muscularis propria are poorly resolved during colitis. Maintaining homeostasis in this unique niche is of critical importance, highlighted by the poorer prognosis of inflammatory bowel disease associated with inflammation in the muscularis propria. Methods: This study utilizes single-cell RNA sequencing to survey the immune cell populations within the muscularis propria of normal colon and DSS-induced colitis. Results: In naïve conditions, transcriptional duality is observed in MMφ with two major supopulations: conventional resident Cx3cr1+ MMφs and Lyve1+ MMφs. During colitis, significant changes occur within the muscularis propria, with increases in B-cells, T-cells, monocytes, neutrophils, and dendritic cells. Unlike in the mucosa, single cell transcriptomics indicates that resident MMφs are retained during colitis and exhibit plasticity toward an inflammatory profile. Lyve1+ MMφs, which express anti-inflammatory marker CD163, are absent during colitis. In contrast, resident Cx3cr1+ MMφs remain during colitis. Conclusions: Our findings provide a resource for understanding the immune system in the muscularis propria niche during colitis and resolve the heterogeneity and origins of proinflammatory MMφs during colitis by demonstrating the plasticity of the persistent MMφ population.
Project description:Genes expression in Ly6C+/F4/80+ inflammatory macrophages, CX3CR1+/F4/80+ tissue resident macrophages and Ly6G+/F4/80- neutrophils which were isolated from day 3 wounds in C57/B6 mice aged 8 weeks by cell sorting Ly6C+ macrophages expressed higher (over 5 folds) levels of 241 genes compared to CX3CR1+ macrophages, and 3382 genes compared to neutrophils