Project description:Nitric oxide (NO) produced by macrophages (MØs) is toxic to both host tissues and invading pathogens and its regulation is therefore essential to suppress host cytotoxicity. MØ arginase 1 (Arg1) inhibits NO production by competing with NO synthases for arginine, the common substrate of NO synthases and arginases. Two signal transduction pathways control Arg1 expression in MØs. First, a MyD88-dependent pathway induces Arg1 in intracellular infections, while a second Stat6-dependent pathway is required for Arg1 expression in alternativelyactivated MØs. We found that mycobacteria-infected MØs produce soluble factors that induce Arg1 in an autocrine-paracrine manner via Stat3. We identify these factors as IL-6, IL-10 and GCSF. We further establish that Arg1 expression is controlled by the MyD88-dependent production of IL-6, IL-10 and G-CSF rather than cell intrinsic MyD88 signaling to Arg1. Our data reveal the MyD88-dependent pathway of Arg1induction following BCG infection requires Stat3 activation and may result in the development of an immunosuppressive niche in granulomas due to the induced Arg1 production in surrounding uninfected MØs We used microarrays to perform genome wide expression analysis in mycobacteria-infected macrophages from C57Bl/6 WT and MyD88-knockout mice.
Project description:We compared arginase-1+ macrophages (macrophages were defined by flow cytometry as CD45hi CD11b+ Ly6G-) with arginase-1- brain macrophages following traumatic brain injury (TBI) by isolating these cells from YARG transgenic mice, which express YFP under the arginase-1 promoter. Both cell populations were isolated from YARG brain tissues one day following TBI. We also examined the expression profile of peripheral blood monocytes (monocytes were defined by flow cytometry as CD11bhi F4/80+) from injured YARG mice and from normal YARG mice. Peripheral blood samples were compared to TBI brain macrophages to assess gene expression changes before and after infiltration into the brain. TBI macrophage subsets were identified by using a reporter mouse strain (YARG) that expresses eYFP from an IRES inserted at the 3' end of the gene for arginase-1 (Arg1), a hallmark of alternatively activated (M2) macrophages. One day after TBI, 21±1.5% of ipsilateral brain macrophages expressed relatively high levels of Arg1 as detected by YFP. Gene expression analysis of Arg1+ and Arg1- brain macrophage populations revealed that these populations were distinct from either classically activated (M1) macrophages or M2 macrophages, with features of both. The Arg1+ cells differed from Arg1- cells in multiple aspects, most notably in their chemokine repertoires. Thus, the macrophage response to TBI involves recruitment of at least two major macrophage subsets. Overall, our data indicate that the macrophage response to TBI is heterogeneous and unique. Four groups (Arg1- brain macrophages post-TBI, Arg1+ brain macrophages post-TBI, normal blood monocytes, blood monocytes post-TBI) were analyzed. Four replicates of each group were analyzed for a total of 16 samples (only 3 replicates of the blood monocyte groups are included in this submission).
Project description:Arginase 1 (Arg1), which converts L-arginine into ornithine and urea, exerts pleiotropic immunoregulatory effects. Patients with inflammatory bowel disease (IBD) show an enhanced expression and activity of Arg1 in the intestinal (sub-)mucosa, but the function of Arg1 in IBD remains poorly characterized. Here, we found that Arg1 expression correlates with the degree of inflammation in colitic tissues of IBD patients. In mice with - experimental colitis Arg1 was upregulated in an IL-4-/IL-13- and intestinal microbiota-dependent manner. Tie2-Cre+/-Arg1fl/fl mice lacking Arg1 in hematopoietic and endothelial cells recovered faster from colitis than Arg1-expressing littermates. This correlated with decreased vessel density, compositional changes in the intestinal microbiota, diminished infiltration by myeloid cellsand an accumulation of intraluminal polyamines that are associated with epithelial healing. Dietary L-arginine restriction abolished the protective effect of Arg1-deletion, suggesting that protection is related to an increased availability of L-arginine. Fecal microbiota transfers from Tie2-Cre+/-Arg1fl/fl mice into wildtype recipients restored the protective, anti-inflammatory phenotype while transfers from wildtype littermates into Arg1-deficient mice prevented the accelerated recovery from colitis. Thus, altered intestinal microbiota and metabolic products in Tie2-Cre+/-Arg1fl/fl mice account for the accelerated resolution from colitis in the absence of Arg1. Subsequently, L-arginine serves as novel therapeutic and diagnostic target for clinical intervention in IBD patients.
Project description:Nitric oxide (NO) produced by macrophages (MØs) is toxic to both host tissues and invading pathogens and its regulation is therefore essential to suppress host cytotoxicity. MØ arginase 1 (Arg1) inhibits NO production by competing with NO synthases for arginine, the common substrate of NO synthases and arginases. Two signal transduction pathways control Arg1 expression in MØs. First, a MyD88-dependent pathway induces Arg1 in intracellular infections, while a second Stat6-dependent pathway is required for Arg1 expression in alternativelyactivated MØs. We found that mycobacteria-infected MØs produce soluble factors that induce Arg1 in an autocrine-paracrine manner via Stat3. We identify these factors as IL-6, IL-10 and GCSF. We further establish that Arg1 expression is controlled by the MyD88-dependent production of IL-6, IL-10 and G-CSF rather than cell intrinsic MyD88 signaling to Arg1. Our data reveal the MyD88-dependent pathway of Arg1induction following BCG infection requires Stat3 activation and may result in the development of an immunosuppressive niche in granulomas due to the induced Arg1 production in surrounding uninfected MØs
Project description:Despite IL-9 functioning as a pleiotropic cytokine in mucosal environments, the IL-9 responsive cell repertoire is still not well defined. Here, we found IL-9 mediates pro-allergic activities by targeting lung macrophages. IL-9 inhibits alveolar macrophage expansion and promotes recruitment of monocytes that develop into CD11c+/- interstitial macrophage populations. Interstitial macrophages were required for IL-9-dependent allergic responses. Mechanistically, IL-9 affects the function of lung macrophages by inducing Arg1 activity. Compared to Arg1-deficient lung macrophages, Arg1-expressing macrophages co-express greater amounts of CCL5. Adoptive transfer of Arg1+ lung macrophages but not Arg1- lung macrophages can recover allergic inflammation that is lost in Il9r-/- mice. In parallel, the elevated expression of IL-9, IL-9R, Arg1 and CCL5 is correlated with disease in asthma patients. Thus, our study uncovers an IL-9/macrophage/Arg1 axis as a potential therapeutic target for allergic airway inflammation.
Project description:Arginase 1 (Arg1), the enzyme catalyzing the conversion of arginine to ornithine, is a hallmark of IL-10-producing immunoregulatory M2 macrophages. However, its expression in T cells is disputed. Here, we demonstrate that induction of Arg1 expression is a key feature of lung CD4+ T cells during mouse in vivo influenza infection. Conditional ablation of Arg1 in CD4+ T cells accelerated both virus-specific T helper 1 (Th1) effector responses and its resolution, resulting in efficient viral clearance and reduced lung pathology. Using unbiased transcriptomics and metabolomics, we found that Arg1-deficiency was distinct from Arg2-deficiency and caused altered glutamine metabolism. Rebalancing this perturbed glutamine flux normalized the cellular Th1 response. CD4+ T cells from rare ARG1-deficient patients or CRISPR-Cas9-mediated ARG1-deletion in healthy donor cells phenocopied the murine cellular phenotype. Collectively, CD4+ T cell-intrinsic Arg1 functions as an unexpected rheostat regulating the kinetics of the mammalian Th1 lifecycle with implications for Th1-associated tissue pathologies.
Project description:In this phase I first-in-humans-study a vaccine consisting of arginase-1 (ARG1) peptides and the adjuvant Montanide ISA-51 will be tested in ten patients with metastatic solid tumors. Patients will be treated with an ARG1 vaccine every third week for 45 weeks.
Project description:Brain myeloid cells, include infiltrating macrophages and resident microglia, play an essential role in responding to and inducing neurodegenerative diseases, such as Alzheimer’s disease (AD). Genome-wide association studies (GWAS) implicate many AD casual and risk genes enriched in brain myeloid cells. Coordinated arginine metabolism through arginase 1 (Arg1) is critical for brain myeloid cells to perform biological functions, whereas dysregulated arginine metabolism disrupts them. Altered arginine metabolism is proposed as a new biomarker pathway for AD. We previously reported Arg1 deficiency in myeloid biased cells using lysozyme M (LysM) promoter-driven deletion worsened amyloidosis-related neuropathology and behavioral impairment. However, it remains unclear how Arg1 deficiency in these cells impacts the whole brain to promote amyloidosis. Herein, we aim to determine how Arg1 deficiency driven by LysM restriction during amyloidosis affects fundamental neurodegenerative pathways at the transcriptome level. By applying several bioinformatic tools and analyses, we found that amyloid-β (Aβ) stimulated transcriptomic signatures in autophagy-related pathways and myeloid cells' inflammatory response. At the same time, myeloid Arg1 deficiency during amyloidosis promoted gene signatures of lipid metabolism, myelination, and migration of myeloid cells. Focusing on Aβ associated glial transcriptomic signatures, we found myeloid Arg1 deficiency up-regulated glial gene transcripts that positively correlated with Aβ plaque burden. We also observed that Aβ preferentially activated disease-associated microglial signatures to increase phagocytic response, whereas myeloid Arg1 deficiency selectively promoted homeostatic microglial signature that is non-phagocytic. These transcriptomic findings suggest a critical role for proper Arg1 function during normal and pathological challenges associated with amyloidosis. Furthermore, understanding pathways that govern Arg1 metabolism may provide new therapeutic opportunities to rebalance immune function and improve microglia/macrophage fitness.
Project description:Ischemic/hypoxic injury significantly damages vascular function, detrimentally im-pact-ing patient outcomes. Changes in mitochondrial structure and function are closely associated with ischemia/hypoxia-induced vascular dysfunction. The mecha-nism of this process remains elusive. Using rat models of ischemia and hypoxic vas-cular smooth muscle cells (VSMCs), we combined transmission electron microscopy, super-resolution microscopy, and metabolic analysis to analyze the structure and function change of mitochondrial cristae. Multi-omics approaches revealed arginase 1 (Arg1) upregulation in ischemic VSMCs, confirmed by in vivo and in vitro knock-out models showing Arg1's protective effects on mitochondrial cristae, mitochondrial and vascular function, and limited the release of mtDNA. Mechanistically, Arg1 in-teracting with Mic10 led to mitochondrial cristae remodeling, together with hypox-ia-induced VDAC1 lactylation resulting in the opening of MPTP and release of mtDNA of VSMCs. The released mtDNA led to PANoptosis of VSMCs via activation of the cGAS-STING pathway. ChIP-qPCR results demonstrated that lactate-mediated Arg1 up-regulation was due to H3K18la upregulation. VSMCs targeted nano-material PLGA-PEI-siRNA@PM-α-SMA (NP-siArg1) significantly improved vascular dysfunction. This study uncovers a new mechanism of vascular dysfunction following ischemic/hypoxic injury: a damaging positive feedback loop mediated by lactate-regulated Arg1 expression between the nucleus and mitochondria, leading to mitochondria cristae disorder and mtDNA release, culminating in VSMCs PANopto-sis. Targeting VSMCs Arg1 inhibition offers a potential therapeutic strategy to alle-viate ischemia/hypoxia-induced vascular impairments
Project description:Tumor-associated macrophages (TAM) have attracted attention as they can modulate key cancer-related activities, yet TAM represent a heterogenous group of cells that remain incompletely characterized. In growing tumors, TAM are often referred to as M2-like macrophages, which are cells that display immunosuppressive and tumorigenic functions and express the enzyme arginase 1 (Arg1). Here we combined single cell intravital imaging with scRNA seq to uncover the topography and molecular profiles of Arg1+ macrophages in mice. We further assessed how immunotherapeutic interventions impact these cells directly in vivo. We show that: i) Arg1+ macrophages are more abundant in tumors compared to other organs; ii) there exist two morphologically distinct subsets of Arg1 TAM defined by previously unknown markers (Gbp2b, Bst1, Sgk1, Pmepa1, Ms4a7); iii) anti-Programmed Cell Death-1 (aPD-1) therapy decreases the number of Arg1+ TAM while increasing Arg1– TAM; iv) accordingly, pharmacological inhibition of arginase 1 does not synergize with aPD-1 therapy. Overall, this research defines subsets of immunosuppressive myeloid cells with powerful complementary single cell analytical approaches that pave the way for a more intricate understanding of TAM behavior.