RESUMO
In systemic lupus erythematosus (SLE) loss of immune tolerance, autoantibody production and immune complex deposition are required but not sufficient for organ damage1. How inflammatory signals are initiated and amplified in the setting of autoimmunity remains elusive. Here, we set out to dissect layers and hierarchies of autoimmune kidney inflammation in order to identify tissue-specific cellular hubs that amplify auto-inflammatory responses. Using high-resolution single-cell profiling of kidney immune and parenchymal cells, in combination with antibody blocking and genetic deficiency, we show that tissue-resident NKp46+ innate lymphoid cells (ILC) are crucial signal amplifiers of disease-associated macrophage expansion and epithelial cell injury in lupus nephritis, downstream of autoantibody production. NKp46 signaling in a distinct subset of ILC1 instructed an unconventional immune-regulatory transcriptional program, which included the expression of the myeloid cell growth factor CSF2. CSF2 production by NKp46+ ILC promoted the population expansion of monocyte-derived macrophages. Blockade of the NKp46 receptor (using the antibody mNCR1.152) or genetic deficiency of NKp46 abrogated epithelial cell injury. The same cellular and molecular patterns were operative in human lupus nephritis. Our data support that NKp46+ ILC1 promote parenchymal cell injury by granting monocyte-derived macrophages access to epithelial cell niches. NKp46 activation in ILC1 thus constitutes a previously unrecognized, critical tissue rheostat that amplifies organ damage in autoimmune hosts, with broad implications for inflammatory pathologies and therapies.
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Recent single-cell RNA sequencing studies have revealed distinct microglial states in development and disease. These include proliferative-region-associated microglia (PAMs) in developing white matter and disease-associated microglia (DAMs) prevalent in various neurodegenerative conditions. PAMs and DAMs share a similar core gene signature. However, the extent of the dynamism and plasticity of these microglial states, as well as their functional significance, remains elusive, partly due to the lack of specific tools. Here, we generated an inducible Cre driver line, Clec7a-CreERT2, that targets PAMs and DAMs in the brain parenchyma. Utilizing this tool, we profiled labeled cells during development and in several disease models, uncovering convergence and context-dependent differences in PAM and DAM gene expression. Through long-term tracking, we demonstrated microglial state plasticity. Lastly, we specifically depleted DAMs in demyelination, revealing their roles in disease recovery. Together, we provide a versatile genetic tool to characterize microglial states in CNS development and disease.
Assuntos
Plasticidade Celular , Microglia , Remielinização , Microglia/fisiologia , Animais , Camundongos , Plasticidade Celular/genética , Doenças Desmielinizantes/genética , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Modelos Animais de Doenças , Encéfalo , Bainha de Mielina/metabolismo , Substância Branca/patologiaRESUMO
The gut microbiota and tumor-associated macrophages (TAMs) affect tumor responses to anti-programmed cell death protein 1 (PD-1) immune checkpoint blockade. Reprogramming TAM by either blocking or deleting the macrophage receptor triggering receptor on myeloid cells 2 (TREM2) attenuates tumor growth, and lack of functional TREM2 enhances tumor elimination by anti-PD-1. Here, we found that anti-PD-1 treatment combined with TREM2 deficiency in mice induces proinflammatory programs in intestinal macrophages and a concomitant expansion of Ruminococcus gnavus in the gut microbiota. Gavage of wild-type mice with R. gnavus enhanced anti-PD-1-mediated tumor elimination, recapitulating the effect occurring in the absence of TREM2. A proinflammatory intestinal environment coincided with expansion, increased circulation, and migration of TNF-producing CD4+ T cells to the tumor bed. Thus, TREM2 remotely controls anti-PD-1 immune checkpoint blockade through modulation of the intestinal immune environment and microbiota, with R. gnavus emerging as a potential probiotic agent for increasing responsiveness to anti-PD-1.
Assuntos
Microbioma Gastrointestinal , Imunoterapia , Macrófagos , Glicoproteínas de Membrana , Camundongos Endogâmicos C57BL , Receptor de Morte Celular Programada 1 , Receptores Imunológicos , Animais , Camundongos , Microbioma Gastrointestinal/imunologia , Inibidores de Checkpoint Imunológico/farmacologia , Imunoterapia/métodos , Intestinos/imunologia , Macrófagos/imunologia , Glicoproteínas de Membrana/imunologia , Glicoproteínas de Membrana/deficiência , Glicoproteínas de Membrana/genética , Camundongos Knockout , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Receptor de Morte Celular Programada 1/imunologia , Receptores Imunológicos/imunologia , Receptores Imunológicos/deficiência , Receptores Imunológicos/genéticaRESUMO
Microglia help limit the progression of Alzheimer's disease (AD) by constraining amyloid-ß (Aß) pathology, effected through a balance of activating and inhibitory intracellular signals delivered by distinct cell surface receptors. Human leukocyte Ig-like receptor B4 (LILRB4) is an inhibitory receptor of the immunoglobulin (Ig) superfamily that is expressed on myeloid cells and recognizes apolipoprotein E (ApoE) among other ligands. Here, we find that LILRB4 is highly expressed in the microglia of patients with AD. Using mice that accumulate Aß and carry a transgene encompassing a portion of the LILR region that includes LILRB4, we corroborated abundant LILRB4 expression in microglia wrapping around Aß plaques. Systemic treatment of these mice with an anti-human LILRB4 monoclonal antibody (mAb) reduced Aß load, mitigated some Aß-related behavioral abnormalities, enhanced microglia activity, and attenuated expression of interferon-induced genes. In vitro binding experiments established that human LILRB4 binds both human and mouse ApoE and that anti-human LILRB4 mAb blocks such interaction. In silico modeling, biochemical, and mutagenesis analyses identified a loop between the two extracellular Ig domains of LILRB4 required for interaction with mouse ApoE and further indicated that anti-LILRB4 mAb may block LILRB4-mApoE by directly binding this loop. Thus, targeting LILRB4 may be a potential therapeutic avenue for AD.
Assuntos
Doença de Alzheimer , Microglia , Humanos , Camundongos , Animais , Microglia/metabolismo , Anticorpos/metabolismo , Receptores de Superfície Celular/metabolismo , Amiloide/metabolismo , Modelos Animais de Doenças , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Apolipoproteínas E , Leucócitos/metabolismo , Camundongos Transgênicos , Glicoproteínas de Membrana/metabolismo , Receptores Imunológicos/metabolismoRESUMO
Outer retinal degenerations, including age-related macular degeneration (AMD), are characterized by photoreceptor and retinal pigment epithelium (RPE) atrophy. In these blinding diseases, macrophages accumulate at atrophic sites, but their ontogeny and niche specialization remain poorly understood, especially in humans. We uncovered a unique profile of microglia, marked by galectin-3 upregulation, at atrophic sites in mouse models of retinal degeneration and human AMD. In disease models, conditional deletion of galectin-3 in microglia led to phagocytosis defects and consequent augmented photoreceptor death, RPE damage, and vision loss, indicating protective roles. Mechanistically, Trem2 signaling orchestrated microglial migration to atrophic sites and induced galectin-3 expression. Moreover, pharmacologic Trem2 agonization led to heightened protection but in a galectin-3-dependent manner. In elderly human subjects, we identified this highly conserved microglial population that expressed galectin-3 and Trem2. This population was significantly enriched in the macular RPE-choroid of AMD subjects. Collectively, our findings reveal a neuroprotective population of microglia and a potential therapeutic target for mitigating retinal degeneration.
Assuntos
Galectina 3 , Glicoproteínas de Membrana , Receptores Imunológicos , Degeneração Retiniana , Idoso , Animais , Humanos , Camundongos , Atrofia , Galectina 3/genética , Macrófagos , Glicoproteínas de Membrana/genética , Microglia , Receptores Imunológicos/genéticaRESUMO
Deciphering the cell-state transitions underlying immune adaptation across time is fundamental for advancing biology. Empirical in vivo genomic technologies that capture cellular dynamics are currently lacking. We present Zman-seq, a single-cell technology recording transcriptomic dynamics across time by introducing time stamps into circulating immune cells, tracking them in tissues for days. Applying Zman-seq resolved cell-state and molecular trajectories of the dysfunctional immune microenvironment in glioblastoma. Within 24 hours of tumor infiltration, cytotoxic natural killer cells transitioned to a dysfunctional program regulated by TGFB1 signaling. Infiltrating monocytes differentiated into immunosuppressive macrophages, characterized by the upregulation of suppressive myeloid checkpoints Trem2, Il18bp, and Arg1, over 36 to 48 hours. Treatment with an antagonistic anti-TREM2 antibody reshaped the tumor microenvironment by redirecting the monocyte trajectory toward pro-inflammatory macrophages. Zman-seq is a broadly applicable technology, enabling empirical measurements of differentiation trajectories, which can enhance the development of more efficacious immunotherapies.
Assuntos
Glioblastoma , Humanos , Perfilação da Expressão Gênica , Glioblastoma/patologia , Imunoterapia , Células Matadoras Naturais , Macrófagos , Microambiente Tumoral , Análise de Célula ÚnicaRESUMO
Recent single-cell RNA sequencing studies have revealed distinct microglial states in development and disease. These include proliferative region-associated microglia (PAM) in developing white matter and disease-associated microglia (DAM) prevalent in various neurodegenerative conditions. PAM and DAM share a similar core gene signature and other functional properties. However, the extent of the dynamism and plasticity of these microglial states, as well as their functional significance, remains elusive, partly due to the lack of specific tools. Here, we report the generation of an inducible Cre driver line, Clec7a-CreERT2, designed to target PAM and DAM in the brain parenchyma. Utilizing this tool, we profile labeled cells during development and in several disease models, uncovering convergence and context-dependent differences in PAM/DAM gene expression. Through long-term tracking, we demonstrate surprising levels of plasticity in these microglial states. Lastly, we specifically depleted DAM in cuprizone-induced demyelination, revealing their roles in disease progression and recovery.
RESUMO
Cancer immunotherapies have revolutionized treatment but have shown limited success as single-agent therapies highlighting the need to understand the origin, assembly, and dynamics of heterogeneous tumor immune niches. Here, we use single-cell and imaging-based spatial analysis to elucidate three microenvironmental neighborhoods surrounding the heterogeneous basal cell carcinoma tumor epithelia. Within the highly proliferative neighborhood, we find that TREM2+ skin cancer-associated macrophages (SCAMs) support the proliferation of a distinct tumor epithelial population through an immunosuppression-independent manner via oncostatin-M/JAK-STAT3 signaling. SCAMs represent a unique tumor-specific TREM2+ population defined by VCAM1 surface expression that is not found in normal homeostatic skin or during wound healing. Furthermore, SCAMs actively proliferate and self-propagate through multiple serial tumor passages, indicating long-term potential. The tumor rapidly drives SCAM differentiation, with intratumoral injections sufficient to instruct naive bone marrow-derived monocytes to polarize within days. This work provides mechanistic insights into direct tumor-immune niche dynamics independent of immunosuppression, providing the basis for potential combination tumor therapies.
Assuntos
Carcinoma Basocelular , Neoplasias Cutâneas , Humanos , Macrófagos/metabolismo , Monócitos , Carcinogênese/metabolismo , Carcinoma Basocelular/metabolismo , Transdução de Sinais , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/metabolismo , Glicoproteínas de Membrana/metabolismo , Receptores Imunológicos/metabolismoRESUMO
Triggering receptor expressed on myeloid cells 2 (TREM2) plays important roles in brain microglial function in neurodegenerative diseases, but the role of TREM2 in the GBM TME has not been examined. Here, we found that TREM2 is highly expressed in myeloid subsets, including macrophages and microglia in human and mouse GBM tumors and that high TREM2 expression correlates with poor prognosis in patients with GBM. TREM2 loss of function in human macrophages and mouse myeloid cells increased interferon-γ-induced immunoactivation, proinflammatory polarization, and tumoricidal capacity. In orthotopic mouse GBM models, mice with chronic and acute Trem2 loss of function exhibited decreased tumor growth and increased survival. Trem2 inhibition reprogrammed myeloid phenotypes and increased programmed cell death protein 1 (PD-1)+CD8+ T cells in the TME. Last, Trem2 deficiency enhanced the effectiveness of anti-PD-1 treatment, which may represent a therapeutic strategy for patients with GBM.
Assuntos
Glioblastoma , Humanos , Camundongos , Animais , Glioblastoma/tratamento farmacológico , Glioblastoma/genética , Glioblastoma/metabolismo , Linfócitos T CD8-Positivos , Microglia/metabolismo , Macrófagos , Células Mieloides/metabolismo , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Receptores Imunológicos/genética , Receptores Imunológicos/metabolismoRESUMO
Natural killer (NK) cells are commonly reduced in human tumors, enabling many to evade surveillance. Here, we sought to identify cues that alter NK cell activity in tumors. We found that, in human lung cancer, the presence of NK cells inversely correlated with that of monocyte-derived macrophages (mo-macs). In a murine model of lung adenocarcinoma, we show that engulfment of tumor debris by mo-macs triggers a pro-tumorigenic program governed by triggering receptor expressed on myeloid cells 2 (TREM2). Genetic deletion of Trem2 rescued NK cell accumulation and enabled an NK cell-mediated regression of lung tumors. TREM2+ mo-macs reduced NK cell activity by modulating interleukin (IL)-18/IL-18BP decoy interactions and IL-15 production. Notably, TREM2 blockade synergized with an NK cell-activating agent to further inhibit tumor growth. Altogether, our findings identify a new axis, in which TREM2+ mo-macs suppress NK cell accumulation and cytolytic activity. Dual targeting of macrophages and NK cells represents a new strategy to boost antitumor immunity.
Assuntos
Células Matadoras Naturais , Neoplasias Pulmonares , Humanos , Camundongos , Animais , Macrófagos , Células Mieloides , Glicoproteínas de Membrana/genética , Receptores Imunológicos/genéticaRESUMO
Demyelination is a hallmark of multiple sclerosis, leukoencephalopathies, cerebral vasculopathies, and several neurodegenerative diseases. The cuprizone mouse model is widely used to simulate demyelination and remyelination occurring in these diseases. Here, we present a high-resolution single-nucleus RNA sequencing (snRNA-seq) analysis of gene expression changes across all brain cells in this model. We define demyelination-associated oligodendrocytes (DOLs) and remyelination-associated MAFBhi microglia, as well as astrocytes and vascular cells with signatures of altered metabolism, oxidative stress, and interferon response. Furthermore, snRNA-seq provides insights into how brain cell types connect and interact, defining complex circuitries that impact demyelination and remyelination. As an explicative example, perturbation of microglia caused by TREM2 deficiency indirectly impairs the induction of DOLs. Altogether, this study provides a rich resource for future studies investigating mechanisms underlying demyelinating diseases.
Assuntos
Doenças Desmielinizantes , Remielinização , Animais , Camundongos , Doenças Desmielinizantes/metabolismo , Transcriptoma/genética , Encéfalo/metabolismo , Oligodendroglia/metabolismo , Microglia/metabolismo , Cuprizona/toxicidade , Modelos Animais de Doenças , Camundongos Endogâmicos C57BL , Bainha de Mielina/metabolismoRESUMO
Microglia are central players in brain innate immunity and have been the subject of extensive research in Alzheimer's disease (AD). In this review, we aim to summarize the genetic and functional discoveries that have advanced our understanding of microglia reactivity to AD pathology. Given the heightened AD risk posed by rare variants of the microglial triggering receptor expressed on myeloid cells 2 (TREM2), we will focus on the studies addressing the impact of this receptor on microglia responses to amyloid plaques, tauopathy and demyelination pathologies in mouse and human. Finally, we will discuss the implications of recent discoveries on microglia and TREM2 biology on potential therapeutic strategies for AD.
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Doença de Alzheimer , Humanos , Animais , Camundongos , Doença de Alzheimer/patologia , Microglia/metabolismo , Peptídeos beta-Amiloides/metabolismo , Encéfalo/metabolismo , Imunidade Inata , Modelos Animais de Doenças , Glicoproteínas de Membrana/genética , Receptores Imunológicos/genéticaRESUMO
Genetic studies have highlighted microglia as pivotal in orchestrating Alzheimer's disease (AD). Microglia that adhere to Aß plaques acquire a transcriptional signature, "disease-associated microglia" (DAM), which largely emanates from the TREM2-DAP12 receptor complex that transmits intracellular signals through the protein tyrosine kinase SYK. The human TREM2R47H variant associated with high AD risk fails to activate microglia via SYK. We found that SYK-deficient microglia cannot encase Aß plaques, accelerating brain pathology and behavioral deficits. SYK deficiency impaired the PI3K-AKT-GSK-3ß-mTOR pathway, incapacitating anabolic support required for attaining the DAM profile. However, SYK-deficient microglia proliferated and advanced to an Apoe-expressing prodromal stage of DAM; this pathway relied on the adapter DAP10, which also binds TREM2. Thus, microglial responses to Aß involve non-redundant SYK- and DAP10-pathways. Systemic administration of an antibody against CLEC7A, a receptor that directly activates SYK, rescued microglia activation in mice expressing the TREM2R47H allele, unveiling new options for AD immunotherapy.
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Doença de Alzheimer , Microglia , Animais , Camundongos , Humanos , Microglia/metabolismo , Glicogênio Sintase Quinase 3 beta/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Peptídeos beta-Amiloides/metabolismo , Doença de Alzheimer/patologia , Placa Amiloide/metabolismo , Encéfalo/metabolismo , Modelos Animais de Doenças , Quinase Syk/metabolismo , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Receptores Imunológicos/metabolismoRESUMO
Sepsis is a leading cause of death in critical illness, and its pathophysiology varies depending on preexisting medical conditions. Here we identified nonalcoholic fatty liver disease (NAFLD) as an independent risk factor for sepsis in a large clinical cohort and showed a link between mortality in NAFLD-associated sepsis and hepatic mitochondrial and energetic metabolism dysfunction. Using in vivo and in vitro models of liver lipid overload, we discovered a metabolic coordination between hepatocyte mitochondria and liver macrophages that express triggering receptor expressed on myeloid cells-2 (TREM2). Trem2-deficient macrophages released exosomes that impaired hepatocytic mitochondrial structure and energy supply because of their high content of miR-106b-5p, which blocks Mitofusin 2 (Mfn2). In a mouse model of NAFLD-associated sepsis, TREM2 deficiency accelerated the initial progression of NAFLD and subsequent susceptibility to sepsis. Conversely, overexpression of TREM2 in liver macrophages improved hepatic energy supply and sepsis outcome. This study demonstrates that NAFLD is a risk factor for sepsis, providing a basis for precision treatment, and identifies hepatocyte-macrophage metabolic coordination and TREM2 as potential targets for future clinical trials.
Assuntos
Comunicação Celular , Hepatócitos/metabolismo , Macrófagos/metabolismo , Glicoproteínas de Membrana/metabolismo , Hepatopatia Gordurosa não Alcoólica/metabolismo , Receptores Imunológicos/metabolismo , Sepse/metabolismo , Animais , Metabolismo Energético/genética , Feminino , GTP Fosfo-Hidrolases/genética , GTP Fosfo-Hidrolases/metabolismo , Hepatócitos/patologia , Humanos , Macrófagos/patologia , Masculino , Glicoproteínas de Membrana/genética , Camundongos , Camundongos Knockout , MicroRNAs/genética , MicroRNAs/metabolismo , Mitocôndrias Hepáticas/genética , Mitocôndrias Hepáticas/metabolismo , Mitocôndrias Hepáticas/patologia , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Hepatopatia Gordurosa não Alcoólica/genética , Hepatopatia Gordurosa não Alcoólica/patologia , Receptores Imunológicos/genética , Sepse/genética , Sepse/patologiaRESUMO
Checkpoint immunotherapy unleashes T cell control of tumors, but is undermined by immunosuppressive myeloid cells. TREM2 is a myeloid receptor that transmits intracellular signals that sustain microglial responses during Alzheimer's disease. TREM2 is also expressed by tumor-infiltrating macrophages. Here, we found that Trem2-/- mice are more resistant to growth of various cancers than wild-type mice and are more responsive to anti-PD-1 immunotherapy. Furthermore, treatment with anti-TREM2 mAb curbed tumor growth and fostered regression when combined with anti-PD-1. scRNA-seq revealed that both TREM2 deletion and anti-TREM2 are associated with scant MRC1+ and CX3CR1+ macrophages in the tumor infiltrate, paralleled by expansion of myeloid subsets expressing immunostimulatory molecules that promote improved T cell responses. TREM2 was expressed in tumor macrophages in over 200 human cancer cases and inversely correlated with prolonged survival for two types of cancer. Thus, TREM2 might be targeted to modify tumor myeloid infiltrates and augment checkpoint immunotherapy.
Assuntos
Imunoterapia , Glicoproteínas de Membrana/metabolismo , Neoplasias/terapia , Receptor de Morte Celular Programada 1/imunologia , Receptores Imunológicos/metabolismo , Animais , Anticorpos Monoclonais/uso terapêutico , Receptor 1 de Quimiocina CX3C/metabolismo , Linhagem Celular Tumoral , Modelos Animais de Doenças , Humanos , Linfócitos do Interstício Tumoral/citologia , Linfócitos do Interstício Tumoral/metabolismo , Glicoproteínas de Membrana/deficiência , Glicoproteínas de Membrana/genética , Metilcolantreno/toxicidade , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neoplasias/induzido quimicamente , Neoplasias/patologia , Prognóstico , Receptor de Morte Celular Programada 1/metabolismo , Receptores Imunológicos/deficiência , Receptores Imunológicos/genética , Microambiente TumoralRESUMO
BACKGROUND: Type 2 immune dysfunction contributes to acute lung injury and lethality following haemorrhagic shock (HS) and trauma. Group 2 innate lymphoid cells (ILC2s) play a significant role in the regulation of type 2 immune responses. However, the role of ILC2 in post-HS acute lung injury and the underlying mechanism has not yet been elucidated. OBJECTIVE: To investigate the regulatory role of ILC2s in HS-induced acute lung injury and the underlying mechanism in patients and animal model. METHODS: Circulating markers of type 2 immune responses in patients with HS and healthy controls were characterised. Using a murine model of HS, the role of high-mobility group box 1 (HMGB1)-receptor for advanced glycation end products (RAGE) signalling in regulation of ILC2 proliferation, survival and function was determined. And the role of ILC2 in inducing type 2 immune dysfunction was assessed as well. RESULTS: The number of ILC2s was significantly increased in the circulation of patients with HS that was correlated with the increase in the markers of type 2 immune responses in the patients. Animal studies showed that HMGB1 acted via RAGE to induce ILC2 accumulation in the lungs by promoting ILC2 proliferation and decreasing ILC2 death. The expansion of ILC2s resulted in type 2 cytokines secretion and eosinophil infiltration in the lungs, both of which contributed to lung injury after HS. CONCLUSIONS: These results indicate that HMGB1-RAGE signalling plays a critical role in regulating ILC2 biological function that aggravates type 2 lung inflammation following HS.
Assuntos
Lesão Pulmonar Aguda/imunologia , Proteína HMGB1/metabolismo , Imunidade Inata/imunologia , Interleucinas/metabolismo , Linfócitos/imunologia , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Choque Hemorrágico/sangue , Lesão Pulmonar Aguda/patologia , Animais , Antígenos de Neoplasias/sangue , Estudos de Casos e Controles , Proliferação de Células , Sobrevivência Celular , Modelos Animais de Doenças , Eosinófilos , Feminino , Proteína HMGB1/sangue , Proteína HMGB1/genética , Humanos , Interleucinas/sangue , Contagem de Linfócitos , Linfócitos/fisiologia , Masculino , Camundongos , Pessoa de Meia-Idade , Proteínas Quinases Ativadas por Mitógeno/sangue , Receptor para Produtos Finais de Glicação Avançada/genética , Choque Hemorrágico/complicações , Transdução de SinaisRESUMO
BACKGROUND: Adipose tissue remodeling plays a significant role in obesity-induced insulin resistance. Published studies reported that level of trigger receptor expressed on myeloid cells 2 (TREM2) in adipose tissue is up-regulated in animal models of obesity. This study aims to investigate whether TREM2 regulates obesity-induced insulin resistance via modulating adipose tissue remodeling in mice of high-fat diet (HFD). METHODS: Wild-type (WT) and TREM2-/- mice were both fed with a controlled-fat diet (CFD) or HFD for 12 weeks and studied for obesity and insulin resistance. Meanwhile, epididymal adipose tissue (EAT) was examined for morphological and pathological changes to determine adipose tissue remodeling. After that, adipocyte-derived MCP-1 was measured in adipocytes, adipose tissue and circulation. Next, inflammatory cytokines were determined in adipose tissue macrophages (ATM). At last, livers were analyzed for hepatic steatosis. RESULTS: TREM2-/- mice on HFD had increased obesity and insulin resistance compared with WT counterparts. Adipose tissue from TREM2-/- mice exhibited reduced mass but greater adipocyte hypertrophy and increased adipocyte death. Besides, adipocyte-derived MCP-1 was down-regulated in TREM2-/- mice, and circulating MCP-1 level was lower than that of WT mice. Furthermore, TREM2-/- mice displayed reduced infiltration of F4/80+CD11c+ macrophages into adipose tissue, which was unable to form crown-like structures (CLS) to clean dead adipocytes and cellular contents. Also, TREM2 deficiency augmented inflammatory response of adipose tissue macrophages in HFD mice. In addition, TREM2-/- mice demonstrated more severe hepatic steatosis than WT counterparts under HFD feeding. CONCLUSIONS: Trigger receptor expressed on myeloid cells 2 may function as a feedback mechanism to curb obesity-induced insulin resistance via regulating adipose tissue remodeling.
Assuntos
Tecido Adiposo/patologia , Dieta Hiperlipídica , Comportamento Alimentar , Resistência à Insulina , Glicoproteínas de Membrana/metabolismo , Obesidade/patologia , Receptores Imunológicos/metabolismo , Adipócitos/metabolismo , Adipócitos/patologia , Animais , Quimiocina CCL2/metabolismo , Regulação para Baixo , Hipertrofia , Inflamação/patologia , Cirrose Hepática/patologia , Macrófagos/patologia , Glicoproteínas de Membrana/deficiência , Camundongos Endogâmicos C57BL , Receptores Imunológicos/deficiência , Regulação para CimaRESUMO
Sepsis claims an estimated 30 million episodes and 6 million deaths per year, and treatment options are rather limited. Human neutrophil peptides 1-3 (HNP1-3) are the most abundant neutrophil granule proteins but their neutrophil content varies because of unusually extensive gene copy number polymorphism. A genetic association study found that increased copy number of the HNP-encoding gene DEFA1/DEFA3 is a risk factor for organ dysfunction during sepsis development. However, direct experimental evidence demonstrating that these risk alleles are pathogenic for sepsis is lacking because the genes are present only in some primates and humans. Here, we generate DEFA1/DEFA3 transgenic mice with neutrophil-specific expression of the peptides. We show that mice with high copy number of DEFA1/DEFA3 genes have more severe sepsis-related vital organ damage and mortality than mice with low copy number of DEFA1/DEFA3 or wild-type mice, resulting from more severe endothelial barrier dysfunction and endothelial cell pyroptosis after sepsis challenge. Mechanistically, HNP-1 induces endothelial cell pyroptosis via P2X7 receptor-mediating canonical caspase-1 activation in a NLRP3 inflammasome-dependent manner. Based on these findings, we engineered a monoclonal antibody against HNP-1 to block the interaction with P2X7 and found that the blocking antibody protected mice carrying high copy number of DEFA1/DEFA3 from lethal sepsis. We thus demonstrate that DEFA1/DEFA3 copy number variation strongly modulates sepsis development in vivo and explore a paradigm for the precision treatment of sepsis tailored by individual genetic information.
Assuntos
Predisposição Genética para Doença , Sepse/genética , alfa-Defensinas/genética , Alelos , Animais , Anticorpos Monoclonais/genética , Anticorpos Monoclonais/imunologia , Variações do Número de Cópias de DNA/genética , Modelos Animais de Doenças , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Humanos , Inflamassomos/genética , Inflamassomos/imunologia , Camundongos , Camundongos Transgênicos , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Piroptose/genética , Piroptose/imunologia , Receptores Purinérgicos P2X7/genética , Fatores de Risco , Sepse/sangue , Sepse/patologia , alfa-Defensinas/antagonistas & inibidores , alfa-Defensinas/imunologiaRESUMO
Background/aim: Sphingosine 1-phosphate receptor 2 (S1PR2), a member of the seven-transmembrane receptor family, can be activated by its natural ligand sphingosine 1-phosphate (S1P) to initiate signal transduction and is involved in a wide range of biological effects such as immune cell migration and vascular permeability. Its relationship with neuropathic pain (NP) has not been reported. In this study, the effects of S1PR2 on the development of NP were studied. Materials and methods: We generated a model of NP by partial sciatic nerve ligation (pSNL). The 50% paw withdrawal threshold of the wild-type (WT) group and the S1PR2 deficiency group were measured at several time points after surgery. The inflammatory factor levels of the two groups were measured by real-time quantitative polymerase chain reaction (RT-PCR). Neutrophil infiltration and glial cell activation were detected by immunofluorescence. Matrix metalloproteinase 9 (MMP9) and its substrate myelin basic protein (MBP) were measured by RT-PCR, western blotting, and immunofluorescence. Result: The S1PR2 deficiency group showed a reduction in 50% paw withdrawal threshold compared with WT mice (P < 0.05) at 3 days after the operation. In the ligated sciatic nerve of the S1PR2 deficiency group, the mRNA expression of IL-1ß was increased; the numbers of infiltrating neutrophils and activated astrocytes were also increased. The expression of MMP9 was elevated while MBP was decreased. Conclusion: S1PR2 deficiency could increase the pain sensitivity of a NP mouse model and promote the development of NP
Assuntos
Neuralgia/metabolismo , Receptores de Lisoesfingolipídeo/deficiência , Receptores de Lisoesfingolipídeo/genética , Nervo Isquiático/lesões , Animais , Citocinas/metabolismo , Modelos Animais de Doenças , Metaloproteinases da Matriz/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Infiltração de Neutrófilos/genética , Receptores de Lisoesfingolipídeo/metabolismo , Receptores de Esfingosina-1-Fosfato , Medula Espinal/químicaRESUMO
BACKGROUND: Bacterial pneumonia is one of the most common diagnoses and a leading cause of death in the intensive care unit. NR4A1 is an early response gene that has been identified as a vital regulator of immune and inflammatory responses. This study aims to explore the role of NR4A1 in Escherichia coli (E. coli) pneumonia. METHODS: Alveolar macrophages (AMs) were isolated from wild-type (WT) and NR4A1 knock out (Nr4a1) mice, and the NR4A1 expression and phagocytic capacity against E. coli were measured in vitro. WT and Nr4a1 mice were subjected to E. coli or sham pneumonia. Bacterial load, lung injury severity, inflammatory cell infiltration, and cytokines were assessed at 0, 4, and 18âh after surgery. Survival rates within 48âh were evaluated in WT and Nr4a1 mice. In addition, NR4A1 antagonist (DIM-C-pPhCO2Me) was also used to confirm the role of NR4A1 in vivo and ex vivo. RESULTS: NR4A1 was rapidly induced in AMs at 15âmin after E. coli stimulation. Compared with untreated WT AMs, NR4A1 deficiency and DIM-C-pPhCO2Me treatment showed an enhanced phagocytic function (47.72â±â0.74% vs. 62.3â±â0.9%, Pâ<â0.001; 11.79â±â1.21% vs. 30.08â±â0.79%, Pâ<â0.001, respectively) at 30âmin after the E. coli challenge in vitro. NR4A1 deficiency significantly improved the survival rate (33.3% in WT vs. 82.4% in Nr4a1, Pâ<â0.01), which is comparable with DIM-C-pPhCO2Me pretreatment. The survival advantage of Nr4a1 mice was associated with decreased bacterial burden and inflammation and alleviated lung damage. CONCLUSIONS: These data demonstrate that NR4A1 impairs the phagocytic capacity of AMs and disrupts the host defense against invading bacteria, worsening the outcome of E. coli pneumonia in mice.