RESUMEN
Iron deficiencies are the most common nonenteric syndromes observed in patients with inflammatory bowel disease, but little is known about their impacts on immune tolerance. Here we show that homeostasis of regulatory T cells in the intestine was dependent on high cellular iron levels, which were fostered by pentanoate, a short-chain fatty acid produced by intestinal microbiota. Iron deficiencies in Treg caused by the depletion of Transferrin receptor 1, a major iron transporter, result in the abrogation of Treg in the intestine and lethal autoimmune disease. Transferrin receptor 1 is required for differentiation of c-Maf+ Treg, major constituents of intestinal Treg. Mechanistically, iron enhances the translation of HIF-2α mRNA, and HIF-2α in turn induces c-Maf expression. Importantly, microbiota-produced pentanoate promotes iron uptake and Treg differentiation in the intestine. This subsequently restores immune tolerance and ameliorated iron deficiencies in mice with colitis. Our results thus reveal an association between nutrient uptake and immune tolerance in the intestine.
Asunto(s)
Deficiencias de Hierro , Microbiota , Ratones , Animales , Hierro/metabolismo , Intestinos , Tolerancia Inmunológica , Linfocitos T Reguladores , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , ValeratosRESUMEN
As one of the most induced genes in activated macrophages, immune-responsive gene 1 (IRG1) encodes a mitochondrial metabolic enzyme catalysing the production of itaconic acid (ITA). Although ITA has an anti-inflammatory property, the underlying mechanisms are not fully understood. Here we show that ITA is a potent inhibitor of the TET-family DNA dioxygenases. ITA binds to the same site on TET2 as the co-substrate α-ketoglutarate, inhibiting TET2 catalytic activity. Lipopolysaccharide treatment, which induces Irg1 expression and ITA accumulation, inhibits Tet activity in macrophages. Transcriptome analysis reveals that TET2 is a major target of ITA in suppressing lipopolysaccharide-induced genes, including those regulated by the NF-κB and STAT signalling pathways. In vivo, ITA decreases the levels of 5-hydroxymethylcytosine, reduces lipopolysaccharide-induced acute pulmonary oedema as well as lung and liver injury, and protects mice against lethal endotoxaemia, depending on the catalytic activity of Tet2. Our study thus identifies ITA as an immune modulatory metabolite that selectively inhibits TET enzymes to dampen the inflammatory responses.
Asunto(s)
Dioxigenasas , Animales , ADN , Dioxigenasas/metabolismo , Lipopolisacáridos/toxicidad , Ratones , Succinatos/metabolismo , Succinatos/farmacologíaRESUMEN
BACKGROUND: Loss of dystrophin protein causes Duchenne muscular dystrophy (DMD), characterized by progressive degeneration of cardiac and skeletal muscles, and mortality in adolescence or young adulthood. Although cardiac failure has risen as the leading cause of mortality in patients with DMD, effective therapeutic interventions remain underdeveloped, in part, because of the lack of a suitable preclinical model. METHODS: We analyzed a novel murine model of DMD created by introducing a 4-bp deletion into exon 4, one of the exons encoding the actin-binding domain 1 of dystrophin (referred to as DmdE4* mice). Echocardiography, microcomputed tomography, muscle force measurement, and histological analysis were performed to determine cardiac and skeletal muscle defects in these mice. Using this model, we examined the feasibility of using a cytidine base editor to install exon skipping and rescue dystrophic cardiomyopathy in vivo. AAV9-based CRISPR/Cas9-AID (eTAM) together with AAV9-sgRNA was injected into neonatal DmdE4* mice, which were analyzed 2 or 12 months after treatment to evaluate the extent of exon skipping, dystrophin restoration, and phenotypic improvements of cardiac and skeletal muscles. RESULTS: DmdE4* mice recapitulated many aspects of human DMD, including shortened life span (by ≈50%), progressive cardiomyopathy, kyphosis, profound loss of muscle strength, and myocyte degeneration. A single-dose administration of AAV9-eTAM instituted >50% targeted exon skipping in the Dmd transcripts and restored up to 90% dystrophin in the heart. As a result, early ventricular remodeling was prevented and cardiac and skeletal muscle functions were improved, leading to an increased life span of the DmdE4* mice. Despite gradual decline of AAV vector and base editor expression, dystrophin restoration and pathophysiological rescue of muscular dystrophy were long lasted for at least 1 year. CONCLUSIONS: Our study demonstrates the feasibility and efficacy to institute exon skipping through an enhanced TAM (eTAM) for therapeutic application(s).
Asunto(s)
Desaminasas APOBEC , Sistemas CRISPR-Cas , Cardiomiopatías , Distrofina , Exones , Distrofia Muscular de Duchenne , Desaminasas APOBEC/biosíntesis , Desaminasas APOBEC/genética , Animales , Cardiomiopatías/genética , Cardiomiopatías/metabolismo , Dependovirus , Distrofina/biosíntesis , Distrofina/genética , Vectores Genéticos , Humanos , Ratones , Ratones Endogámicos mdx , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/metabolismo , Distrofia Muscular de Duchenne/terapiaRESUMEN
Plasma cells provide high-affinity antibodies against invading pathogens. Although transcriptional and epigenetic mechanisms have been extensively studied for plasma cell differentiation, how these mechanisms respond to environmental cues remains largely unexplored. In this study, we show that ascorbic acid (vitamin C), an essential nutrient, is able to promote plasma cell differentiation and humoral immune response by enhancing TET2/3-mediated DNA demethylation. Ascorbic acid treatment during B cell activation has persistent effects on later plasma cell differentiation by predisposing germinal center B cells toward the plasma cell lineage. Conversely, ascorbic acid deficiency in vivo blocks plasma cell differentiation and attenuates the humoral immune response following antigen immunization. We further demonstrate that such effects of ascorbic acid on plasma cell differentiation require DNA methylcytosine oxidases TET2 and TET3. Our study thus reveals a previously uncharacterized link between essential nutrients and epigenetic regulation of plasma cell differentiation and humoral immune response.
Asunto(s)
Ácido Ascórbico/uso terapéutico , Desmetilación del ADN/efectos de los fármacos , Proteínas de Unión al ADN/efectos de los fármacos , Dioxigenasas/efectos de los fármacos , Plasma/metabolismo , Animales , Ácido Ascórbico/farmacología , Humanos , RatonesRESUMEN
The mitochondrial and nuclear genomes coordinate and co-evolve in eukaryotes in order to adapt to environmental changes. Variation in the mitochondrial genome is capable of affecting expression of genes on the nuclear genome. Sex-specific mitochondrial genetic control of gene expression has been demonstrated in Drosophila melanogaster, where males were found to drive most of the total variation in gene expression. This has potential implications for male-related health and disease resulting from variation in mtDNA solely inherited from the mother. We used a family-based study comprised of 47,323 gene expression probes and 78 mitochondrial SNPs (mtSNPs) from n = 846 individuals to examine the extent of mitochondrial genetic control of gene expression in humans. This identified 15 significant probe-mtSNP associations (P<10-8) corresponding to 5 unique genes on the mitochondrial and nuclear genomes, with three of these genes corresponding to mitochondrial genetic control of gene expression in the nuclear genome. The associated mtSNPs for three genes (one cis and two trans associations) were replicated (P < 0.05) in an independent dataset of n = 452 unrelated individuals. There was no evidence for sexual dimorphic gene expression in any of these five probes. Sex-specific effects were examined by applying our analysis to males and females separately and testing for differences in effect size. The MEST gene was identified as having the most significantly different effect sizes across the sexes (P≈10-7). MEST was similarly expressed in males and females with the G allele; however, males with the C allele are highly expressed for MEST, while females show no expression of the gene. This study provides evidence for the mitochondrial genetic control of expression of several genes in humans, with little evidence found for sex-specific effects.
Asunto(s)
ADN Mitocondrial/genética , Regulación de la Expresión Génica/genética , Mitocondrias/genética , Biosíntesis de Proteínas/genética , Alelos , Animales , Núcleo Celular/genética , Cromosomas/genética , Drosophila melanogaster/genética , Femenino , Humanos , Masculino , Polimorfismo de Nucleótido Simple/genética , Caracteres SexualesRESUMEN
The fundamental mechanism of gastrointestinal diseases is the imbalance between the attack factor and the protective factor of stomach mucous membrane. It can not outbreak if the protective factor is stronger than the attack factor; otherwise, it will. Attack and protective function inside the stomach are mediated by various factors. These related factors interaction constitutes a complicated network system. This kind of outbreak theories of imbalance in Western medicine is same as that, "The sense of right saves inside, the evil can't do" and "Evil is competing with right, all diseases occur", in Chinese medicine. So, it is the key which points to futher study the interaction between gastrointestinal attack factors and protective factors by traditional Chinese medicine, thus improving the clinical effect.