ABSTRACT: Inflammation switches the differentiation program of Ly6Chi monocytes from anti-inflammatory macrophages to inflammatory dendritic cells in the colon
Project description:Dendritic cells (DCs) and macrophages (MPs) are important for immunological homeostasis in the colon. We found that F4/80hi CX3CR1hi (CD11b+CD103-) cells account for 80% of mouse colonic lamina propria (cLP) MHC-IIhi cells. Both CD11c+ and CD11c- cells within this population were identified as MPs based on multiple criteria, including a MP transcriptome revealed by microarray analysis. These MPs constitutively released high levels of IL-10 at least partially in response to the microbiota via an MyD88-independent mechanism. In contrast, cells expressing low to intermediate levels of F4/80 and CX3CR1 were identified as DCs, based on phenotypic and functional analysis and comprise three separate CD11chi cell populations: CD103+CX3CR1-CD11b- DCs, CD103+CX3CR1-CD11b+ DCs and CD103-CX3CR1intCD11b+ DCs. In non-inflammatory conditions, Ly6Chi monocytes differentiated primarily into CD11c+, but not CD11c- MPs. In contrast, during colitis, Ly6Chi monocytes massively invaded the colon and differentiated into pro-inflammatory CD103-CX3CR1intCD11b+ DCs, which produced high levels of IL-12, IL-23, iNOS and TNF. These findings demonstrate the dual capacity of Ly6Chi blood monocytes to differentiate into either regulatory MPs or inflammatory DCs in the colon, and that the balance of these immunologically antagonistic cell types is dictated by microenvironmental conditions. FACS sorted expression from normal controls
Project description:Nlrp6-/- lamina propria Ly6C-hi monocytes in response to AOM/DSS have deficient TNFα production, but increased production of other pro-inflammatory cytokines as compared to WT NLRP6 is a member of the Nod-like receptor family, whose members are involved in the recognition of microbes and/or tissue injury. NLRP6 was previously demonstrated to regulate the production of IL-18 and is important for protecting mice against chemically-induced intestinal injury and colitis-associated colon cancer. However, the cellular mechanisms by which NLRP6 reduces susceptibility to colonic inflammation remain unclear. Here, we determined that NLRP6 expression is specifically upregulated in Ly6Chi inflammatory monocytes that infiltrate into the colon during dextran sulfate sodium (DSS)-induced inflammation. Adoptive transfer of WT Ly6Chi inflammatory monocytes into Nlrp6-/- mice was sufficient to protect them from mortality, significantly reducing intestinal permeability and damage. NLRP6-deficient inflammatory monocytes were specifically defective in TNFα production, which was important for reducing DSS-induced mortality and dependent on autocrine IL-18 signaling by inflammatory monocytes. Our data reveal a previously unappreciated role for NLRP6 in inflammatory monocytes, which are recruited during intestinal injury to promote barrier function and limit bacteria-driven inflammation. This study also highlights the importance of early cytokine responses, particularly NLRP6-dependent and IL-18-dependent TNFα production in preventing chronic dysregulated inflammation. Ly6Chi monocytes were sorted from lamina propria of WT or Nlrp6-/- mice at day 10 of AOM/2%DSS. RNA was extracted and hybridized to the mouse 2.1 ST array.
Project description:We studied the role of Notch2 signaling in Ly6Chi monocyte cell fate during TLR7-induced acute inflammation. To characterize the gene expression changes involved in monocyte differentiation, we subjected monocyte subsets from peripheral blood of wt and myeloid Notch2 mutant mice after Sham or IMQ treatment to RNA-sequencing and gene expression analysis. We found that Cell-intrinsic Notch2 and TLR7-Myd88 pathways independently and synergistically promote Ly6Clo patrolling monocyte development from Ly6Chi monocytes under inflammatory conditions. At the same time TLR7 stimulation in the absence of functional Notch2 signaling promotes resident tissue macrophage gene expression signatures in monocytes and ectopic differentiation of Ly6Chi monocytes into macrophages and dendritic cells. Thus, Notch2 is a master regulator of Ly6Chi monocyte cell fate and inflammation in response to TLR signaling.
Project description:Dendritic cells (DCs) and macrophages (MPs) are important for immunological homeostasis in the colon. We found that F4/80hi CX3CR1hi (CD11b+CD103-) cells account for 80% of mouse colonic lamina propria (cLP) MHC-IIhi cells. Both CD11c+ and CD11c- cells within this population were identified as MPs based on multiple criteria, including a MP transcriptome revealed by microarray analysis. These MPs constitutively released high levels of IL-10 at least partially in response to the microbiota via an MyD88-independent mechanism. In contrast, cells expressing low to intermediate levels of F4/80 and CX3CR1 were identified as DCs, based on phenotypic and functional analysis and comprise three separate CD11chi cell populations: CD103+CX3CR1-CD11b- DCs, CD103+CX3CR1-CD11b+ DCs and CD103-CX3CR1intCD11b+ DCs. In non-inflammatory conditions, Ly6Chi monocytes differentiated primarily into CD11c+, but not CD11c- MPs. In contrast, during colitis, Ly6Chi monocytes massively invaded the colon and differentiated into pro-inflammatory CD103-CX3CR1intCD11b+ DCs, which produced high levels of IL-12, IL-23, iNOS and TNF. These findings demonstrate the dual capacity of Ly6Chi blood monocytes to differentiate into either regulatory MPs or inflammatory DCs in the colon, and that the balance of these immunologically antagonistic cell types is dictated by microenvironmental conditions.
Project description:Ablative RT results in increased expression of CCL2 within the tumor microenvironment of pancreatic ductal adenocarcinoma (PDAC) and also increased recruitment of CD45+CD11b+Ly6Chi inflammatory monocytes/macrophages. This increase in CCL2 expression and recruitment of inflammatory monocytes/macrophages is a mechanism of resistance to the anti-tumor effects of ablative radiotherapy (RT). We used microarrays to study changes in gene expression patterns of inflammatory monocytes/macrophages sorted from the tumor microenvironment after ablative RT in a subcutenous model of pancreatic adenocarcinoma. From this, we identified 8 genes with an absolute fold change of expression equal to or greater than 2 with a false discovery rate equal to or less than 25 %. A pancreatic cancer tumor cell line derived from spontaneously arising tumors in KrasLSL-G12D/+, Trp53LSL-R172H/+, Pdx1-Cre (KPC) mice was subcutaneously implanted into 8 week old female C57BL/6 and allowed to grow for 14 days. After 14 days, 4 mice received 20 Gy of radiation, and 4 mice received a sham treatment. One day post treatment, tumors were harvested, and inflammatory monocytes/macrophages were isolated using flow sorting based on a surface expression phenotype of CD45+ CD11b+ Ly6Chi. From this cell population, total RNA was extracted for creation of cDNA and hybridization on Affymetrix microarrays. From the microarrays, a set of genes associated with radiation treatment of PDAC was identified.
Project description:Nlrp6-/- lamina propria Ly6C-hi monocytes in response to AOM/DSS have deficient TNFα production, but increased production of other pro-inflammatory cytokines as compared to WT NLRP6 is a member of the Nod-like receptor family, whose members are involved in the recognition of microbes and/or tissue injury. NLRP6 was previously demonstrated to regulate the production of IL-18 and is important for protecting mice against chemically-induced intestinal injury and colitis-associated colon cancer. However, the cellular mechanisms by which NLRP6 reduces susceptibility to colonic inflammation remain unclear. Here, we determined that NLRP6 expression is specifically upregulated in Ly6Chi inflammatory monocytes that infiltrate into the colon during dextran sulfate sodium (DSS)-induced inflammation. Adoptive transfer of WT Ly6Chi inflammatory monocytes into Nlrp6-/- mice was sufficient to protect them from mortality, significantly reducing intestinal permeability and damage. NLRP6-deficient inflammatory monocytes were specifically defective in TNFα production, which was important for reducing DSS-induced mortality and dependent on autocrine IL-18 signaling by inflammatory monocytes. Our data reveal a previously unappreciated role for NLRP6 in inflammatory monocytes, which are recruited during intestinal injury to promote barrier function and limit bacteria-driven inflammation. This study also highlights the importance of early cytokine responses, particularly NLRP6-dependent and IL-18-dependent TNFα production in preventing chronic dysregulated inflammation.
Project description:We investigated the innate immune system in the SOD1 ALS model. We found that splenic Ly6CHi monocytes were activated and their progressive recruitment to the spinal cord, but not brain, correlated with neuronal loss. We found a decrease in resident microglia in the spinal cord with disease progression. Two months prior to disease onset, splenic Ly6CHi monocytes had an M1 signature which included increased CCR2. At one month prior to disease onset, microglia expressed increased CCL2 and other chemotaxis-associated molecules. Microglia derived from the spinal cord of SOD1 mice recruited Ly6C+ monocytes to the CNS. Treatment with anti-Ly6C mAb modulated the Ly6CHi monocyte cytokine profile, reduced monocyte recruitment to the spinal cord, diminished neuronal loss and extended survival. In humans with ALS, CD14+/CD16- monocytes (analogue of Ly6CHi monocytes) exhibited an ALS specific microRNA inflammatory signature similar to that observed in the SOD1 mouse providing a direct link between the animal model and the human disease. Thus, the SOD1-like profile of monocytes in ALS subjects may serve as a biomarker for disease stage or progression. Our results suggest that recruitment of inflammatory monocytes plays an important role in disease progression and that modulation of these cells is a potential therapeutic approach This study used the NanoString nCounter hybridization system and the Nanostring GX Human Immunology and Nanostring Human Inflammation assays to identify and quantitate immune-related genes in blood CD14+CD16- monocytes from ALS, MS and HC subjects Total RNA was isolated from FACS sorted CD14+CD16- blood-derived monocytes from sporadic sALS (n=10), fALS (n=4) and HC (n=10) subjects. RNA was profiled using the Nanostring GX Human Immunology and Nanostring Human Inflammation assays
Project description:Monocytes are circulating myeloid immune precursor cells that are generated in the bone marrow (BM). Upon their release into the circulation, monocytes are recruited to inflammatory sites, where they differentiate into monocyte-derived effector cells. In absence of overt inflammation, monocytes also extravasate into selected tissues, where they complement tissue-resident macrophage compartments. Recent studies have uncovered binary developmental trajectories of monocytes in the BM with Neutrophil-like (NeuMo) and dendritic cell (DC)-like (DCMo) monocytes differentiating downstream of granulocyte-macrophage progenitors (GMP) and macrophage-dendritic cell progenitors (MDP), respectively (Weinreb et al., 2020; Yanez et al., 2017). Yet, the molecular cues that dictate BM monocyte differentiation remain incompletely understood. The COMMD (copper metabolism MURR1 domain) family includes 10 evolutionarily conserved proteins. Functions of COMMD proteins are still being defined, but they seem to play non-redundant roles in regulating transcription and protein trafficking. Utilizing conditional COMMD10 knockout mice we uncovered a role for COMMD10 in limiting inflammasome activation in Ly6Chi monocytes during experimental sepsis and colitis (Mouhadeb et al., 2018), and in supporting phagolysosomal biogenesis and maturation in KCs and BM-derived macrophages infected with Staphylococcus aureus (Ben Shlomo et al., 2019). Hence, these studies mark COMMD10 as a candidate mediator of monocyte and macrophage fate and immune responses. Here we studied the effect of COMMD10-deficiency on Ly6Chi monocyte differentiation. We show that COMMD10-deficiency in steady state Ly6Chi monocytes promotes a differentiation bias towards NeuMo fate.
Project description:Mice deficient in MBD2 (Mbd2-/-) were treated with 2% dextran sulfate sodium or normal drinking water for 6 continuous days. A single cell suspension of colon lamina propria and epithelium was isolated, with monocytes (CD11b+ Ly6CHi, MHC-II+/-), macrophages (CD11b+ Ly6C-MHC-II+), cDC2s (CD11b- CD11c+ CD103+) and epithelial cells (CD45- EpCAM+) purified by FACS. Methyl-CpG-binding domain-2 (Mbd2) acts as an epigenetic regulator of gene expression, by linking DNA methylation to repressive chromatin structure. Although Mbd2 is widely expressed in gastrointestinal immune cells and is implicated in regulating intestinal cancer and anti-helminth responses, its role in controlling colitis has yet to be defined. Indeed, epigenetic control of gene expression in cells that regulate intestinal immunity is generally poorly understood, even though such mechanisms may explain the inability of standard genetic approaches to pinpoint the causes of conditions like inflammatory bowel disease. In this study we demonstrate a vital role for Mbd2 in regulating murine colonic inflammation. Mbd2-/- mice displayed dramatically worse pathology than wild type controls during dextran sulphate sodium (DSS) induced colitis, with increased inflammatory (IL-1β+) monocytes. Profiling of mRNA from innate immune and epithelial cell (EC) populations suggested that Mbd2 suppresses inflammation and pathology via control of innate-epithelial cell crosstalk and T cell recruitment. Consequently, restriction of Mbd2 deficiency to CD11c+ dendritic cells and macrophages, or to ECs, resulted in increased DSS colitis severity. Our identification of this dual role for Mbd2 in regulating the inflammatory capacity of both CD11c+ cells and ECs highlights how epigenetic control mechanisms may limit intestinal inflammatory responses.
Project description:Mice deficient in MBD2 (Mbd2-/-) were treated with 2% dextran sulfate sodium or normal drinking water for 6 continuous days. A single cell suspension of colon lamina propria and epithelium was isolated, with monocytes (CD11b+ Ly6CHi, MHC-II+/-), macrophages (CD11b+ Ly6C-MHC-II+), cDC2s (CD11b- CD11c+ CD103+) and epithelial cells (CD45- EpCAM+) purified by FACS. Methyl-CpG-binding domain-2 (Mbd2) acts as an epigenetic regulator of gene expression, by linking DNA methylation to repressive chromatin structure. Although Mbd2 is widely expressed in gastrointestinal immune cells and is implicated in regulating intestinal cancer and anti-helminth responses, its role in controlling colitis has yet to be defined. Indeed, epigenetic control of gene expression in cells that regulate intestinal immunity is generally poorly understood, even though such mechanisms may explain the inability of standard genetic approaches to pinpoint the causes of conditions like inflammatory bowel disease. In this study we demonstrate a vital role for Mbd2 in regulating murine colonic inflammation. Mbd2-/- mice displayed dramatically worse pathology than wild type controls during dextran sulphate sodium (DSS) induced colitis, with increased inflammatory (IL-1β+) monocytes. Profiling of mRNA from innate immune and epithelial cell (EC) populations suggested that Mbd2 suppresses inflammation and pathology via control of innate-epithelial cell crosstalk and T cell recruitment. Consequently, restriction of Mbd2 deficiency to CD11c+ dendritic cells and macrophages, or to ECs, resulted in increased DSS colitis severity. Our identification of this dual role for Mbd2 in regulating the inflammatory capacity of both CD11c+ cells and ECs highlights how epigenetic control mechanisms may limit intestinal inflammatory responses.