RESUMEN
Disturbances in intestinal immune homeostasis predispose susceptible individuals to type 1 diabetes (T1D). G-protein-coupled receptor 41 (GPR41) is a receptor for short-chain fatty acids (SCFAs) mainly produced by gut microbiota, which plays key roles in maintaining intestinal homeostasis. In this study, we investigated the role of GPR41 in the progression of T1D. In non-obese diabetic (NOD) mice, we found that aberrant reduction of GPR41 expression in the pancreas and colons was associated with the development of T1D. GPR41-deficient (Gpr41-/-) mice displayed significantly exacerbated streptozotocin (STZ)-induced T1D compared to wild-type mice. Furthermore, Gpr41-/- mice showed enhanced gut immune dysregulation and increased migration of gut-primed IFN-γ+ T cells to the pancreas. In bone marrow-derived dendritic cells from Gpr41-/- mice, the expression of suppressor of cytokine signaling 3 (SOCS) was significantly inhibited, while the phosphorylation of STAT3 was significantly increased, thus promoting dendritic cell (DC) maturation. Furthermore, adoptive transfer of bone marrow-derived dendritic cells (BMDC) from Gpr41-/- mice accelerated T1D in irradiated NOD mice. We conclude that GPR41 is essential for maintaining intestinal and pancreatic immune homeostasis and acts as a negative regulator of DC maturation in T1D. GPR41 may be a potential therapeutic target for T1D.
Asunto(s)
Células Dendríticas , Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 1 , Ratones Endogámicos NOD , Ratones Noqueados , Receptores Acoplados a Proteínas G , Estreptozocina , Animales , Diabetes Mellitus Tipo 1/inmunología , Diabetes Mellitus Tipo 1/metabolismo , Receptores Acoplados a Proteínas G/deficiencia , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Ratones , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/inmunología , Ratones Endogámicos C57BL , Factor de Transcripción STAT3/metabolismo , Proteína 3 Supresora de la Señalización de Citocinas/metabolismo , Proteína 3 Supresora de la Señalización de Citocinas/genética , Interferón gamma/metabolismo , Páncreas/metabolismo , Páncreas/patología , Páncreas/inmunología , Masculino , Femenino , Microbioma GastrointestinalRESUMEN
Pulmonary fibrosis is a progressive and fatal fibrotic lung disease with mysterious pathogenesis and limited effective therapies. G protein-coupled receptors (GPRs) participate in a variety of physiologic functions, and several GPRs have critical fibrosis-promoting or -inhibiting roles in pulmonary fibrosis. Here, we explored the role of GPR41 in the pathobiology of pulmonary fibrosis. We found that GPR41 expression was elevated in lung tissues of mice with bleomycin-induced pulmonary fibrosis and lung fibroblasts treated with transforming growth factor-ß1 (TGF-ß1). Knockout of GPR41 attenuated pulmonary fibrosis in mice, as evidenced by improved lung morphology, decreased lung weight and collagen secretion, and down-regulated α-SMA, collagen type I alpha and fibronectin expression in lungs. Additionally, GPR41 knockout inhibited the differentiation of fibroblasts to myofibroblasts, and decreased myofibroblast migration. By further mechanistic analysis, we demonstrated that GPR41 regulated TGF-ß1-induced fibroblast-to-myofibroblast differentiation and Smad2/3 and ERK1/2 phosphorylation via its Gαi/o subunit but not Gßγ subunit. Together, our data indicate that GPR41 is involved in pulmonary fibroblast activation and fibrosis, and GPR41 represents a potential therapeutic target for pulmonary fibrosis.
Asunto(s)
Fibrosis Pulmonar , Animales , Ratones , Bleomicina , Diferenciación Celular , Fibroblastos/metabolismo , Proteínas de Unión al GTP/metabolismo , Pulmón , Sistema de Señalización de MAP Quinasas , Ratones Endogámicos C57BL , Ratones Noqueados , Miofibroblastos/metabolismo , Fosforilación , Fibrosis Pulmonar/metabolismo , Factor de Crecimiento Transformador beta1/metabolismoRESUMEN
The role of short-chain fatty acids (SCFAs) in the brain on the developmental programming of hypertension is poorly understood. The present study explored dysregulated tissue levels of SCFAs and expression of SCFA-sensing receptors in the hypothalamic paraventricular nucleus (PVN), a key forebrain region engaged in neural regulation of blood pressure of offspring to maternal high fructose diet (HFD) exposure. We further investigated the engagement of SCFA-sensing receptors in PVN in the beneficial effects of -biotics (prebiotic, probiotic, synbiotic, and postbiotic) on programmed hypertension. Maternal HFD during gestation and lactation significantly reduced circulating butyrate, along with decreased tissue level of butyrate and increased expression of SCFA-sensing receptors, GPR41 and olfr78, and tissue oxidative stress and neuroinflammation in PVN of HFD offspring that were rectified by oral supplement with -biotics. Gene silencing of GPR41 or olfr78 mRNA in PVN also protected adult HFD offspring from programmed hypertension and alleviated the induced oxidative stress and inflammation in PVN. In addition, oral supplement with postbiotic butyrate restored tissue butyrate levels, rectified expressions of GPR41 and olfr78 in PVN, and protected against programmed hypertension in adult HFD offspring. These data suggest that alterations in tissue butyrate level, expression of GPR41 and olfr78, and activation of SCFA-sensing receptor-dependent tissue oxidative stress and neuroinflammation in PVN could be novel mechanisms that underlie hypertension programmed by maternal HFD exposure in adult offspring. Furthermore, oral -biotics supplementation may exert beneficial effects on hypertension of developmental origin by targeting dysfunctional SCFA-sensing receptors in PVN to exert antioxidant and anti-inflammatory actions in the brain.
Asunto(s)
Hipertensión , Núcleo Hipotalámico Paraventricular , Animales , Ratas , Femenino , Humanos , Núcleo Hipotalámico Paraventricular/metabolismo , Fructosa/efectos adversos , Fructosa/metabolismo , Antioxidantes/metabolismo , Ratas Sprague-Dawley , Hipertensión/prevención & control , Hipertensión/genética , Ácidos Grasos Volátiles/metabolismo , Dieta , Antiinflamatorios/metabolismo , ARN Mensajero/metabolismo , Butiratos/metabolismoRESUMEN
Myocardial ischemia/reperfusion (I/R) injury is still a lack of effective therapeutic drugs, and its molecular mechanism is urgently needed. Studies have shown that the intestinal flora plays an important regulatory role in cardiovascular injury, but the specific mechanism has not been fully elucidated. In this study, we found that an increase in Ang II in plasma was accompanied by an increase in the levels of myocardial injury during myocardial reperfusion in patients with cardiopulmonary bypass. Furthermore, Ang II treatment enhanced mice myocardial I/R injury, which was reversed by caveolin-1 (CAV-1)-shRNA or strengthened by angiotensin-converting enzyme 2 (ACE2)-shRNA. The results showed that CAV-1 and ACE2 have protein interactions and inhibit each other's expression. In addition, propionate, a bacterial metabolite, inhibited the elevation of Ang II and myocardial injury, while GPR41-shRNA abolished the protective effects of propionate on myocardial I/R injury. Clinically, the propionate content in the patient's preoperative stool was related to Ang II levels and myocardial I/R injury levels during myocardial reperfusion. Taken together, propionate alleviates myocardial I/R injury aggravated by Ang II dependent on CAV-1/ACE2 axis through GPR41, which provides a new direction that diet to regulate the intestinal flora for treatment of myocardial I/R injury.
Asunto(s)
Caveolina 1/metabolismo , Daño por Reperfusión Miocárdica/tratamiento farmacológico , Miocardio/metabolismo , Propionatos/farmacología , Receptores Acoplados a Proteínas G/metabolismo , Enzima Convertidora de Angiotensina 2/metabolismo , Animales , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Daño por Reperfusión Miocárdica/metabolismo , Miocardio/patología , Sistema Renina-Angiotensina/efectos de los fármacosRESUMEN
Short-chain fatty acids (SCFAs) play a critical role in regulation of rumen epithelial growth. The mechanisms underlying the regulatory effects of SCFAs on the proliferation of bovine rumen epithelial cells (BRECs) remain unknown; however, SCFAs can bind to G protein-coupled receptor 41 (GPR41); hence, the regulatory effects of SCFAs on BRECs proliferation may be mediated by GPR41. Here, we investigated the molecular mechanisms underlying the effects of SCFAs and GPR41 on BRECs proliferation. We demonstrated that SCFAs activate the expression of GPR41 and inhibit (p < .05) BRECs proliferation, while the GPR41 knockdown (GPR41KD) BRECs exhibited (p < .05) slow proliferation compared with controls. The treatment of BRECs with 10 mM SCFAs significantly enhanced (p < .05) expression of cyclin-dependent kinase inhibitors 1A (CDKN1A), 2A (CDKN2A) and 2B (CDKN2B) and inhibited (p < .05) their transition from G1 to S phase of the cell cycle, compared with controls. Remarkably, the GPR41KD BRECs treated with SCFAs restored high level of CDKN1A, relative to GPR41KD BRECs, but did not affect (p > .05) the expression of CDKN2A and CDKN2B. The GPR41KD BRECs had significantly reduced (p < .05) cyclin-dependent kinase 4 (CDK4) and cyclin D2 mRNA abundance compared with controls. The GPR41KD BRECs treated with SCFAs significantly decreased (p < .05) CDK4, cyclin D2, CDKN2A and CDKN2B mRNA abundance compared with BRECs treated with SCFAs. Overall, our results demonstrated that downregulation of CDK4 and cyclin D2 likely mediates the inhibitory effects of GPR41KD on BRECs proliferation. Additionally, CDKN1A plays a vital role in mediating the inhibitory effect of SCFAs on the BRECs proliferation, and that these changes are not mediated by GPR41.
Asunto(s)
Bovinos , Proliferación Celular/efectos de los fármacos , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/metabolismo , Células Epiteliales/efectos de los fármacos , Ácidos Grasos Volátiles/farmacología , Rumen/citología , Animales , Proliferación Celular/fisiología , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/genética , Células Epiteliales/fisiología , Regulación de la Expresión Génica/efectos de los fármacos , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Regulación hacia Arriba/efectos de los fármacosRESUMEN
Dietary fibers, an integral part of the human diet, require the enzymatic activity of the gut microbiota for complete metabolism into short-chain fatty acids (SCFAs). SCFAs are important modulators of host metabolism and physiology and act in part as signaling molecules by activating G protein-coupled receptors (GPCRs), such as GPR41. Flaxseed fibers improve metabolism in rodents and mice, but their fermentation profiles, effects on enteroendocrine cells, and associated metabolic benefits are unknown. We fed GPR41-red fluorescent protein mice, an enteroendocrine reporter mouse strain, chow, high-fat diet (HFD), or HFD supplemented either with 10% nonfermentable fiber cellulose or fermentable flaxseed fibers for 12 wk to assess changes in cecal gut microbiota, enteroendocrine cell transcriptome in the ileum and colon, and physiological parameters. We observed that flaxseed fibers restructured the gut microbiota and promoted proliferation of the genera Bifidobacterium and Akkermansia compared with HFD. The shifts in cecal bacterial composition restored levels of the SCFAs butyrate similar to the chow diet, resulting in colonic but not ileal enteroendocrine cell transcriptional changes in genes related to cell cycle, mRNA, and protein transport compared with HFD. Consistent with the effects on enteroendocrine functions, flaxseed fibers also protected mice from diet-induced obesity, potentially by preventing a reduction in energy expenditure induced by an HFD. Our study shows that flaxseed fibers alter cecal microbial ecology, are fermented to SCFAs in the cecum, and modulate enteroendocrine cell transcriptome in the colon, which may contribute to their metabolically favorable phenotype.