ABSTRACT
While macrophage heterogeneity during metabolic dysfunction-associated steatohepatitis (MASH) has been described, the fate of these macrophages during MASH regression is poorly understood. Comparing macrophage heterogeneity during MASH progression vs regression, we identified specific macrophage subpopulations that are critical for MASH/fibrosis resolution. We elucidated the restorative pathways and gene signatures that define regression-associated macrophages and establish the importance of TREM2+ macrophages during MASH regression. Liver-resident Kupffer cells are lost during MASH and are replaced by four distinct monocyte-derived macrophage subpopulations. Trem2 is expressed in two macrophage subpopulations: i) monocyte-derived macrophages occupying the Kupffer cell niche (MoKC) and ii) lipid-associated macrophages (LAM). In regression livers, no new transcriptionally distinct macrophage subpopulation emerged. However, the relative macrophage composition changed during regression compared to MASH. While MoKC was the major macrophage subpopulation during MASH, they decreased during regression. LAM was the dominant macrophage subtype during MASH regression and maintained Trem2 expression. Both MoKC and LAM were enriched in disease-resolving pathways. Absence of TREM2 restricted the emergence of LAMs and formation of hepatic crown-like structures. TREM2+ macrophages are functionally important not only for restricting MASH-fibrosis progression but also for effective regression of inflammation and fibrosis. TREM2+ macrophages are superior collagen degraders. Lack of TREM2+ macrophages also prevented elimination of hepatic steatosis and inactivation of HSC during regression, indicating their significance in metabolic coordination with other cell types in the liver. TREM2 imparts this protective effect through multifactorial mechanisms, including improved phagocytosis, lipid handling, and collagen degradation.
Subject(s)
Kupffer Cells , Liver Cirrhosis , Macrophages , Membrane Glycoproteins , Receptors, Immunologic , Receptors, Immunologic/metabolism , Receptors, Immunologic/genetics , Membrane Glycoproteins/metabolism , Membrane Glycoproteins/genetics , Animals , Mice , Macrophages/metabolism , Liver Cirrhosis/metabolism , Liver Cirrhosis/pathology , Liver Cirrhosis/genetics , Kupffer Cells/metabolism , Liver/metabolism , Liver/pathology , Lipid Metabolism , Mice, Inbred C57BL , Male , Lipids , Fatty Liver/metabolism , Fatty Liver/pathology , Fatty Liver/genetics , Mice, KnockoutABSTRACT
Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe clinical disorders that mainly develop from viral respiratory infections, sepsis, and chest injury. Antigen-presenting cells play a pivotal role in propagating uncontrolled inflammation and injury through the excess secretion of pro-inflammatory cytokines and recruitment of immune cells. Autophagy, a homeostatic process that involves the degradation of cellular components, is involved in many processes including lung inflammation. Here, we use a polyinosinic-polycytidylic acid (poly(I:C))-induced lung injury mouse model to mimic viral-induced ALI/ARDS and show that disruption of autophagy in macrophages exacerbates lung inflammation and injury, whereas autophagy induction attenuates this process. Therefore, induction of autophagy in macrophages can be a promising therapeutic strategy in ALI/ARDS.
Subject(s)
Acute Lung Injury , Respiratory Distress Syndrome , Animals , Mice , Antigen-Presenting Cells , Macrophages , Autophagy , Poly I-C/pharmacologyABSTRACT
Here, we present a protocol for isolating human hepatocytes and neural progenitor cells from normal and nonalcoholic steatohepatitis livers. We describe steps for perfusion for scaled-up liver cell isolation and optimization of chemical digestion to achieve maximal yield and cell viability. We then detail a liver cell cryopreservation and potential applications, such as the use of human liver cells as a tool to link experimental and translational research.
Subject(s)
Non-alcoholic Fatty Liver Disease , Humans , Cells, Cultured , Hepatocytes , Cell Separation/methodsABSTRACT
BACKGROUND: The impact of exposure to air pollutants, such as fine particulate matter (PM), on the immune system and its consequences on pediatric asthma, are not well understood. We investigated whether ambient levels of fine PM with aerodynamic diameter ≤2.5 microns (PM2.5 ) are associated with alterations in circulating monocytes in children with or without asthma. METHODS: Monocyte phenotyping was performed by cytometry time-of-flight (CyTOF). Cytokines were measured using cytometric bead array and Luminex assay. ChIP-Seq was utilized to address histone modifications in monocytes. RESULTS: Increased exposure to ambient PM2.5 was linked to specific monocyte subtypes, particularly in children with asthma. Mechanistically, we hypothesized that innate trained immunity is evoked by a primary exposure to fine PM and accounts for an enhanced inflammatory response after secondary stimulation in vitro. We determined that the trained immunity was induced in circulating monocytes by fine particulate pollutants, and it was characterized by the upregulation of proinflammatory mediators, such as TNF, IL-6, and IL-8, upon stimulation with house dust mite or lipopolysaccharide. This phenotype was epigenetically controlled by enhanced H3K27ac marks in circulating monocytes. CONCLUSION: The specific alterations of monocytes after ambient pollution exposure suggest a possible prognostic immune signature for pediatric asthma, and pollution-induced trained immunity may provide a potential therapeutic target for asthmatic children living in areas with increased air pollution.
Subject(s)
Air Pollutants , Air Pollution , Asthma , Humans , Particulate Matter/adverse effects , Monocytes , Trained Immunity , Air Pollutants/adverse effects , Air Pollutants/analysis , Asthma/etiology , Asthma/chemically induced , Air Pollution/adverse effectsABSTRACT
BACKGROUND: Neutrophilic asthma is associated with disease severity and corticosteroid insensitivity. Novel therapies are required to manage this life-threatening asthma phenotype. Programmed cell death protein-1 (PD-1) is a key homeostatic modulator of the immune response for T-cell effector functions. OBJECTIVE: We sought to investigate the role of PD-1 in the regulation of acute neutrophilic inflammation in a murine model of airway hyperreactivity (AHR). METHODS: House dust mite was used to induce and compare neutrophilic AHR in wild-type and PD-1 knockout mice. Then, the therapeutic potential of a human PD-1 agonist was tested in a humanized mouse model in which the PD-1 extracellular domain is entirely humanized. Single-cell RNA sequencing and flow cytometry were mainly used to investigate molecular and cellular mechanisms. RESULTS: PD-1 was highly induced on pulmonary T cells in our inflammatory model. PD-1 deficiency was associated with an increased neutrophilic AHR and high recruitment of inflammatory cells to the lungs. Consistently, PD-1 agonist treatment dampened AHR, decreased neutrophil recruitment, and modulated cytokine production in a humanized PD-1 mouse model. Mechanistically, we demonstrated at the transcriptional and protein levels that the inhibitory effect of PD-1 agonist is associated with the reprogramming of pulmonary effector T cells that showed decreased number and activation. CONCLUSIONS: PD-1 agonist treatment is efficient in dampening neutrophilic AHR and lung inflammation in a preclinical humanized mouse model.
Subject(s)
Asthma , Programmed Cell Death 1 Receptor , Humans , Animals , Mice , Programmed Cell Death 1 Receptor/metabolism , Lung , Th2 Cells , Disease Models, AnimalABSTRACT
There has been a global increase in rates of obesity with a parallel epidemic of non-alcoholic fatty liver disease (NAFLD). Autophagy is an essential mechanism involved in the degradation of cellular material and has an important function in the maintenance of liver homeostasis. Here, we explore the effect of Autophagy-related 5 (Atg5) deficiency in liver CD11c+ cells in mice fed HFD. When compared to control mice, Atg5-deficient CD11c+ mice exhibit increased glucose intolerance and decreased insulin sensitivity when fed HFD. This phenotype is associated with the development of NAFLD. We observe that IL-23 secretion is induced in hepatic CD11c+ myeloid cells following HFD feeding. We demonstrate that both therapeutic and preventative IL-23 blockade alleviates glucose intolerance, insulin resistance and protects against NAFLD development. This study provides insights into the function of autophagy and IL-23 production by hepatic CD11c+ cells in NAFLD pathogenesis and suggests potential therapeutic targets.
Subject(s)
Insulin Resistance , Non-alcoholic Fatty Liver Disease , Animals , Autophagy , Diet, High-Fat/adverse effects , Insulin Resistance/genetics , Interleukin-23/metabolism , Liver/metabolism , Mice , Mice, Inbred C57BL , Non-alcoholic Fatty Liver Disease/metabolismABSTRACT
While pulmonary ILC2s represent one of the major tissue-resident innate lymphoid cell populations at steady state and are key drivers of cytokine secretion in their occupational niche, their role in pulmonary cancer progression remains unclear. As the programmed cell death protein-1 (PD-1) plays a major role in cancer immunotherapy and immunoregulatory properties, here we investigate the specific effect of PD-1 inhibition on ILC2s during pulmonary B16 melanoma cancer metastasis. We demonstrate that PD-1 inhibition on ILC2s suppresses B16 tumor growth. Further, PD-1 inhibition upregulates pulmonary ILC2-derived TNF-α production, a cytotoxic cytokine that directly induces cell death in B16 cells, independent of adaptive immunity. Together, these results highlight the importance of ILC2s and their anti-tumor role in pulmonary B16 cancer progression during PD-1 inhibitory immunotherapy.
Subject(s)
Immune Checkpoint Inhibitors/pharmacology , Lung Neoplasms/drug therapy , Lymphocytes/drug effects , Melanoma, Experimental/drug therapy , Programmed Cell Death 1 Receptor/antagonists & inhibitors , Skin Neoplasms/drug therapy , Tumor Microenvironment , Tumor Necrosis Factor-alpha/metabolism , Animals , Cell Line, Tumor , Disease Progression , Humans , Lung Neoplasms/immunology , Lung Neoplasms/metabolism , Lung Neoplasms/secondary , Lymphocytes/immunology , Lymphocytes/metabolism , Melanoma, Experimental/immunology , Melanoma, Experimental/metabolism , Melanoma, Experimental/secondary , Mice, Inbred BALB C , Mice, Knockout , Programmed Cell Death 1 Receptor/metabolism , Skin Neoplasms/immunology , Skin Neoplasms/metabolism , Skin Neoplasms/pathology , Tumor BurdenABSTRACT
Acute respiratory distress syndrome (ARDS), an inflammatory condition with high mortality rates, is common in severe COVID-19, whose risk is reduced by metformin rather than other anti-diabetic medications. Detecting of inflammasome assembly in post-mortem COVID-19 lungs, we asked whether and how metformin inhibits inflammasome activation while exerting its anti-inflammatory effect. We show that metformin inhibited NLRP3 inflammasome activation and interleukin (IL)-1ß production in cultured and alveolar macrophages along with inflammasome-independent IL-6 secretion, thus attenuating lipopolysaccharide (LPS)- and SARS-CoV-2-induced ARDS. By targeting electron transport chain complex 1 and independently of AMP-activated protein kinase (AMPK) or NF-κB, metformin blocked LPS-induced and ATP-dependent mitochondrial (mt) DNA synthesis and generation of oxidized mtDNA, an NLRP3 ligand. Myeloid-specific ablation of LPS-induced cytidine monophosphate kinase 2 (CMPK2), which is rate limiting for mtDNA synthesis, reduced ARDS severity without a direct effect on IL-6. Thus, inhibition of ATP and mtDNA synthesis is sufficient for ARDS amelioration.
Subject(s)
Adenosine Triphosphate/metabolism , DNA, Mitochondrial/biosynthesis , Inflammasomes/drug effects , Metformin/pharmacology , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , Pneumonia/prevention & control , Animals , COVID-19/metabolism , COVID-19/prevention & control , Cytokines/genetics , Cytokines/metabolism , DNA, Mitochondrial/metabolism , Humans , Inflammasomes/metabolism , Interleukin-1beta/genetics , Interleukin-1beta/metabolism , Lipopolysaccharides/toxicity , Metformin/therapeutic use , Mice , Nucleoside-Phosphate Kinase/metabolism , Pneumonia/metabolism , Respiratory Distress Syndrome/chemically induced , Respiratory Distress Syndrome/prevention & control , SARS-CoV-2/pathogenicitySubject(s)
Antiviral Agents/therapeutic use , COVID-19 Drug Treatment , Interferon-gamma/therapeutic use , SARS-CoV-2/drug effects , Antiviral Agents/pharmacology , Epithelial Cells/chemistry , Humans , Immunity, Mucosal/drug effects , Interferon-gamma/pharmacology , Interferon-gamma/physiology , Receptors, Interferon/analysisABSTRACT
BACKGROUND: Group 2 innate lymphoid cells (ILC2s) are the dominant innate lymphoid cell population in the lungs at steady state, and their release of type 2 cytokines is a central driver in responding eosinophil infiltration and increased airway hyperreactivity. Our laboratory has identified a unique subset of ILC2s in the lungs that actively produce IL-10 (ILC210s). OBJECTIVE: Our aim was to characterize the effector functions of ILC210s in the development and pathology of allergic asthma. METHODS: IL-4-stimulated ILC210s were isolated to evaluate cytokine secretion, transcription factor signaling, metabolic dependence, and effector functions in vitro. ILC210s were also adoptively transferred into Rag2-/-γc-/- mice, which were then challenged with IL-33 and assessed for airway hyperreactivity and lung inflammation. RESULTS: We have determined that the transcription factors cMaf and Blimp-1 regulate IL-10 expression in ILC210s. Strikingly, our results demonstrate that ILC210s can utilize both autocrine and paracrine signaling to suppress proinflammatory ILC2 effector functions in vitro. Further, this subset dampens airway hyperreactivity and significantly reduces lung inflammation in vivo. Interestingly, ILC210s demonstrated a metabolic dependency on the glycolytic pathway for IL-10 production, shifting from the fatty acid oxidation pathway conventionally utilized for proinflammatory effector functions. CONCLUSION: These findings provide an important and previously unrecognized role of ILC210s in diseases associated with ILC2s such as allergic lung inflammation and asthma. They also provide new insights into the metabolism dependency of proinflammatory and anti-inflammatory ILC2 phenotypes.
Subject(s)
Asthma/immunology , Bronchial Hyperreactivity/immunology , Interleukin-10/immunology , Lymphocytes/immunology , Positive Regulatory Domain I-Binding Factor 1/immunology , Proto-Oncogene Proteins c-maf/immunology , Animals , Bronchoalveolar Lavage Fluid/immunology , Female , Male , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, TransgenicABSTRACT
Disturbances in glucose homeostasis and low-grade chronic inflammation culminate into metabolic syndrome that increase the risk for the development of type 2 diabetes mellitus (T2DM). The recently discovered group 2 innate lymphoid cells (ILC2s) are capable of secreting copious amounts of type 2 cytokines to modulate metabolic homeostasis in adipose tissue. In this study, we have established that expression of Death Receptor 3 (DR3), a member of the TNF superfamily, on visceral adipose tissue (VAT)-derived murine and peripheral blood human ILC2s is inducible by IL-33. We demonstrate that DR3 engages the canonical and/or non-canonical NF-κB pathways, and thus stimulates naïve and co-stimulates IL-33-activated ILC2s. Importantly, DR3 engagement on ILC2s significantly ameliorates glucose tolerance, protects against insulin-resistance onset and remarkably reverses already established insulin-resistance. Taken together, these results convey the potent role of DR3 as an ILC2 regulator and introduce DR3 agonistic treatment as a novel therapeutic avenue for treating T2DM.
Subject(s)
Adipose Tissue/metabolism , Diabetes Mellitus, Type 2/metabolism , Lymphocytes/metabolism , Receptors, Tumor Necrosis Factor, Member 25/metabolism , Adipocytes/metabolism , Adolescent , Adult , Aged , Animals , Cytokines/metabolism , DNA-Binding Proteins/genetics , Female , Glucose/metabolism , Homeostasis , Humans , Immunity, Innate , Insulin Resistance , Interleukin-33/metabolism , Intra-Abdominal Fat/metabolism , Male , Metabolic Syndrome/complications , Mice , Mice, Inbred C57BL , Mice, Knockout , Middle Aged , Receptors, Tumor Necrosis Factor, Member 25/therapeutic use , Young AdultABSTRACT
Allergic asthma is a leading chronic disease associated with airway hyperreactivity (AHR). Type-2 innate lymphoid cells (ILC2s) are a potent source of T-helper 2 (Th2) cytokines that promote AHR and lung inflammation. As the programmed cell death protein-1 (PD-1) inhibitory axis regulates a variety of immune responses, here we investigate PD-1 function in pulmonary ILC2s during IL-33-induced airway inflammation. PD-1 limits the viability of ILC2s and downregulates their effector functions. Additionally, PD-1 deficiency shifts ILC2 metabolism toward glycolysis, glutaminolysis and methionine catabolism. PD-1 thus acts as a metabolic checkpoint in ILC2s, affecting cellular activation and proliferation. As the blockade of PD-1 exacerbates AHR, we also develop a human PD-1 agonist and show that it can ameliorate AHR and suppresses lung inflammation in a humanized mouse model. Together, these results highlight the importance of PD-1 agonistic treatment in allergic asthma and underscore its therapeutic potential.
Subject(s)
Asthma/immunology , Asthma/metabolism , Immunity, Innate/immunology , Lymphocytes/metabolism , Programmed Cell Death 1 Receptor/metabolism , Animals , Cytokines/metabolism , DNA-Binding Proteins/genetics , Disease Models, Animal , Humans , Inflammation/immunology , Interleukin Receptor Common gamma Subunit/genetics , Interleukin-33/metabolism , Lung/immunology , Lung/metabolism , Mice , Mice, Inbred BALB C , Mice, Knockout , Programmed Cell Death 1 Receptor/genetics , Th2 Cells/metabolism , TranscriptomeABSTRACT
The gut microbiome is a malleable microbial community that can remodel in response to various factors, including diet, and contribute to the development of several chronic diseases, including atherosclerosis. We devised an in vitro screening protocol of the mouse gut microbiome to discover molecules that can selectively modify bacterial growth. This approach was used to identify cyclic D,L-α-peptides that remodeled the Western diet (WD) gut microbiome toward the low-fat-diet microbiome state. Daily oral administration of the peptides in WD-fed LDLr-/- mice reduced plasma total cholesterol levels and atherosclerotic plaques. Depletion of the microbiome with antibiotics abrogated these effects. Peptide treatment reprogrammed the microbiome transcriptome, suppressed the production of pro-inflammatory cytokines (including interleukin-6, tumor necrosis factor-α and interleukin-1ß), rebalanced levels of short-chain fatty acids and bile acids, improved gut barrier integrity and increased intestinal T regulatory cells. Directed chemical manipulation provides an additional tool for deciphering the chemical biology of the gut microbiome and might advance microbiome-targeted therapeutics.
Subject(s)
Atherosclerosis/microbiology , Gastrointestinal Microbiome , Animals , Anti-Bacterial Agents/pharmacology , Anti-Inflammatory Agents/pharmacology , Atherosclerosis/blood , Bacteria/drug effects , Bacteria/growth & development , Biomarkers/metabolism , Cholesterol/blood , Diet, Western , Feeding Behavior , Female , Gastrointestinal Microbiome/genetics , Gene Expression Regulation/drug effects , Host-Pathogen Interactions/drug effects , Host-Pathogen Interactions/genetics , Immunologic Factors/pharmacology , Mice, Inbred C57BL , Models, Biological , Peptides, Cyclic/chemistry , Peptides, Cyclic/pharmacology , Receptors, LDL/metabolism , Tight Junction Proteins/metabolism , Transcription, GeneticABSTRACT
Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by type 2 inflammation with accumulation of activated group 2 innate lymphoid cells (ILC2s) and elevation of thymic stromal lymphopoietin (TSLP). A member of the TNF superfamily (TNFSF), TNFSF15, is known to induce the production of type 2 cytokines in ILC2s. Although ILC2s have been implicated in CRSwNP, the presence and role of TNFSFs in ILC2-mediated type 2 inflammation in CRSwNP has not been elucidated. Here, we investigate the involvement of TNFSFs in ILC2-mediated type 2 inflammation in CRSwNP. We found that receptor activator of NF-κB (RANK) ligand (RANK-L (TNFSF11)) was significantly elevated in nasal polyps (NPs), and that the receptor of RANK-L, RANK, was expressed on ILC2s in human peripheral blood and NPs. An agonistic antibody against RANK induced production of type 2 cytokines in human ILC2s, and TSLP significantly enhanced this reaction. The membrane-bound RANK-L was detected mainly on CD45 + immune cells, including TH2 cells in NPs. The co-culture of NP-derived ILC2s and TH2 cells significantly enhanced production of type 2 cytokines, and anti-RANK-L monoclonal antibody suppressed this enhancement. In conclusion, RANK-L, together with TSLP, may play an inductive role in the ILC2-mediated type 2 inflammation in CRSwNP.
Subject(s)
Inflammation/immunology , Lymphocytes/immunology , Nasal Polyps/immunology , RANK Ligand/metabolism , Rhinitis/immunology , Sinusitis/immunology , Th2 Cells/immunology , Adolescent , Adult , Aged , Aged, 80 and over , Cells, Cultured , Chronic Disease , Cytokines/metabolism , Female , Humans , Immunity, Innate , Male , Middle Aged , Th2 Cells/metabolism , Young AdultABSTRACT
BACKGROUND: Allergic asthma is a chronic inflammatory disorder characterized by airway hyperreactivity (AHR) and driven by TH2 cytokine production. Group 2 innate lymphoid cells (ILC2s) secrete high amounts of TH2 cytokines and contribute to the development of AHR. Autophagy is a cellular degradation pathway that recycles cytoplasmic content. However, the role of autophagy in ILC2s remains to be fully elucidated. OBJECTIVE: We characterized the effects of autophagy deficiency on ILC2 effector functions and metabolic balance. METHODS: ILC2s from autophagy-deficient mice were isolated to evaluate proliferation, apoptosis, cytokine secretion, gene expression and cell metabolism. Also, autophagy-deficient ILC2s were adoptively transferred into Rag-/-GC-/- mice, which were then challenged with IL-33 and assessed for AHR and lung inflammation. RESULTS: We demonstrate that autophagy is extensively used by activated ILC2s to maintain their homeostasis and effector functions. Deletion of the critical autophagy gene autophagy-related 5 (Atg5) resulted in decreased cytokine secretion and increased apoptosis. Moreover, lack of autophagy among ILC2s impaired their ability to use fatty acid oxidation and strikingly promoted glycolysis, as evidenced by our transcriptomic and metabolite analyses. This shift of fuel dependency led to impaired homeostasis and TH2 cytokine production, thus inhibiting the development of ILC2-mediated AHR. Notably, this metabolic reprogramming was also associated with an accumulation of dysfunctional mitochondria, producing excessive reactive oxygen species. CONCLUSION: These findings provide new insights into the metabolic profile of ILC2s and suggest that modulation of fuel dependency by autophagy is a potentially new therapeutic approach to target ILC2-dependent inflammation.
Subject(s)
Autophagy/immunology , Homeostasis/immunology , Immunity, Innate/immunology , Lymphocytes/immunology , Lymphocytes/metabolism , Animals , Mice , Respiratory Hypersensitivity/immunology , Respiratory Hypersensitivity/metabolismABSTRACT
Group 2 innate lymphoid cells (ILC2s) can initiate pathologic inflammation in allergic asthma by secreting copious amounts of type 2 cytokines, promoting lung eosinophilia and airway hyperreactivity (AHR), a cardinal feature of asthma. We discovered that the TNF/TNFR2 axis is a central immune checkpoint in murine and human ILC2s. ILC2s selectively express TNFR2, and blocking the TNF/TNFR2 axis inhibits survival and cytokine production and reduces ILC2-dependent AHR. The mechanism of action of TNFR2 in ILC2s is through the non-canonical NF-κB pathway as an NF-κB-inducing kinase (NIK) inhibitor blocks the costimulatory effect of TNF-α. Similarly, human ILC2s selectively express TNFR2, and using hILC2s, we show that TNFR2 engagement promotes AHR through a NIK-dependent pathway in alymphoid murine recipients. These findings highlight the role of the TNF/TNFR2 axis in pulmonary ILC2s, suggesting that targeting TNFR2 or relevant signaling is a different strategy for treating patients with ILC2-dependent asthma.
Subject(s)
Lymphocytes/immunology , Protein Serine-Threonine Kinases/genetics , Receptors, Tumor Necrosis Factor, Type II/genetics , Respiratory Hypersensitivity/immunology , Signal Transduction/immunology , Adoptive Transfer , Animals , Cell Survival , Disease Models, Animal , Female , Gene Expression Regulation , Humans , Lung/immunology , Lung/pathology , Lymphocyte Transfusion , Lymphocytes/pathology , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , NF-kappa B/genetics , NF-kappa B/immunology , Protein Isoforms/genetics , Protein Isoforms/immunology , Protein Serine-Threonine Kinases/immunology , Receptors, Tumor Necrosis Factor, Type II/immunology , Respiratory Hypersensitivity/genetics , Respiratory Hypersensitivity/pathology , Tumor Necrosis Factor-alpha/genetics , Tumor Necrosis Factor-alpha/immunology , NF-kappaB-Inducing KinaseABSTRACT
Group 2 Innate lymphoid cells (ILC2) contribute significantly to allergic inflammation. However, the role of microbiota on ILC2s remains to be unraveled. Here we show that short chain fatty acids (SCFAs), such as butyrate, derived from fermentation of dietary fibers by the gut microbiota inhibit pulmonary ILC2 functions and subsequent development of airway hyperreactivity (AHR). We further show that SCFAs modulate GATA3, oxidative phosphorylation, and glycolytic metabolic pathways in pulmonary ILC2s. The observed phenotype is associated with increased IL-17a secretion by lung ILC2s and linked to enhanced neutrophil recruitment to the airways. Finally, we show that butyrate-producing gut bacteria in germ-free mice effectively suppress ILC2-driven AHR. Collectively, our results demonstrate a previously unrecognized role for microbial-derived SCFAs on pulmonary ILC2s in the context of AHR. The data suggest strategies aimed at modulating metabolomics and microbiota in the gut, not only to treat, but to prevent lung inflammation and asthma.
Subject(s)
Asthma , Butyric Acid/immunology , Dietary Fiber/administration & dosage , Gastrointestinal Microbiome , Lymphocytes/immunology , Neutrophils/immunology , Animals , Asthma/immunology , Asthma/microbiology , Asthma/pathology , Gastrointestinal Microbiome/drug effects , Gastrointestinal Microbiome/immunology , Immunity, Innate/drug effects , Inflammation/immunology , Inflammation/pathology , Lymphocytes/pathology , Mice , Mice, Inbred BALB C , Mice, Knockout , Neutrophils/pathologyABSTRACT
Metabolic syndrome is characterized by disturbances in glucose homeostasis and the development of low-grade systemic inflammation, which increase the risk to develop type 2 diabetes mellitus (T2DM). Type-2 innate lymphoid cells (ILC2s) are a recently discovered immune population secreting Th2 cytokines. While previous studies show how ILC2s can play a critical role in the regulation of metabolic homeostasis in the adipose tissue, a therapeutic target capable of modulating ILC2 activation has yet to be identified. Here, we show that GITR, a member of the TNF superfamily, is expressed on both murine and human ILC2s. Strikingly, we demonstrate that GITR engagement of activated, but not naïve, ILC2s improves glucose homeostasis, resulting in both protection against insulin resistance onset and amelioration of established insulin- resistance. Together, these results highlight the critical role of GITR as a novel therapeutic molecule against T2DM and its fundamental role as an immune checkpoint for activated ILC2s.
Subject(s)
Diabetes Mellitus, Type 2/immunology , Glucocorticoid-Induced TNFR-Related Protein/immunology , Lymphocytes/immunology , Lymphocytes/metabolism , Adipose Tissue/immunology , Adipose Tissue/metabolism , Animals , Cytokines/immunology , Cytokines/metabolism , Diabetes Mellitus, Type 2/metabolism , Glucocorticoid-Induced TNFR-Related Protein/metabolism , Glucose/metabolism , Homeostasis , Humans , Immunity, Innate , Insulin Resistance , Mice , Mice, Inbred C57BL , Mice, Knockout , Th2 Cells/metabolismABSTRACT
BACKGROUND: Allergic asthma is a prevalent inflammatory disease of the airways caused by dysregulated immune balance in the lungs with incompletely understood pathogenesis. The recently identified type 2 innate lymphoid cells (ILC2s) play significant roles in the pathogenesis of asthma. Although ILC2-activating factors have been identified, the mechanisms that suppress ILC2s remain largely unknown. Plasmacytoid dendritic cells (pDCs) are important in antiviral immunity and in maintaining tolerance to inert antigens. OBJECTIVE: We sought to address the role of pDCs in regulating ILC2 function and ILC2-mediated airway hyperreactivity (AHR) and lung inflammation. METHODS: We used several murine models, including BDCA-2-diphtheria toxin receptor (DTR) transgenic and IFN-α receptor 1-deficient mice, as well as purified primary ILC2s, to reach our objective. We extended and validated our findings to human ILC2s. RESULTS: We show that activation of pDCs through Toll-like receptor 7/8 suppresses ILC2-mediated AHR and airway inflammation and that depletion of pDCs reverses this suppression. We further show that pDCs suppress cytokine production and the proliferation rate while increasing the apoptosis rate of ILC2s through IFN-α production. Transcriptomic analysis of both human and murine ILC2s confirms the activation of regulatory pathways in ILC2s by IFN-α. CONCLUSION: Activation of pDCs alleviates AHR and airway inflammation by suppressing ILC2 function and survival. Our findings reveal a novel regulatory pathway in ILC2-mediated pulmonary inflammation with important clinical implications.