RESUMEN
Glucagon is secreted by pancreatic α cells in response to hypoglycemia and increases hepatic glucose output through hepatic glucagon receptors (GCGRs). There is evidence supporting the notion of extrapancreatic glucagon but its source and physiological functions remain elusive. Intestinal tissue samples were obtained from patients undergoing surgical resection of cancer. Mass spectrometry analysis was used to detect glucagon from mucosal lysate. Static incubations of mucosal tissue were performed to assess glucagon secretory response. Glucagon concentration was quantitated using a highly specific sandwich enzyme-linked immunosorbent assay. A cholesterol uptake assay and an isolated murine colonic motility assay were used to assess the physiological functions of intestinal GCGRs. Fully processed glucagon was detected by mass spectrometry in human intestinal mucosal lysate. High glucose evoked significant glucagon secretion from human ileal tissue independent of sodium glucose cotransporter and KATP channels, contrasting glucose-induced glucagon-like peptide 1 (GLP-1) secretion. The GLP-1 receptor agonist Exendin-4 attenuated glucose-induced glucagon secretion from the human ileum. GCGR blockade significantly increased cholesterol uptake in human ileal crypt culture and markedly slowed ex vivo colonic motility. Our findings describe the human gut as a potential source of extrapancreatic glucagon and demonstrate a novel enteric glucagon/GCGR circuit with important physiological functions beyond glycemic regulation.
Asunto(s)
Glucagón/metabolismo , Mucosa Intestinal/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Colesterol/metabolismo , Estudios de Cohortes , Femenino , Péptido 1 Similar al Glucagón/metabolismo , Glucosa/metabolismo , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Pathogenic autoantibodies arise in many autoimmune diseases, but it is not understood how the cells making them evade immune checkpoints. Here, single-cell multi-omics analysis demonstrates a shared mechanism with lymphoid malignancy in the formation of public rheumatoid factor autoantibodies responsible for mixed cryoglobulinemic vasculitis. By combining single-cell DNA and RNA sequencing with serum antibody peptide sequencing and antibody synthesis, rare circulating B lymphocytes making pathogenic autoantibodies were found to comprise clonal trees accumulating mutations. Lymphoma driver mutations in genes regulating B cell proliferation and V(D)J mutation (CARD11, TNFAIP3, CCND3, ID3, BTG2, and KLHL6) were present in rogue B cells producing the pathogenic autoantibody. Antibody V(D)J mutations conferred pathogenicity by causing the antigen-bound autoantibodies to undergo phase transition to insoluble aggregates at lower temperatures. These results reveal a pre-neoplastic stage in human lymphomagenesis and a cascade of somatic mutations leading to an iconic pathogenic autoantibody.
Asunto(s)
Autoanticuerpos/genética , Enfermedades Autoinmunes/genética , Linfocitos B/inmunología , Linfoma/genética , Animales , Autoanticuerpos/inmunología , Enfermedades Autoinmunes/inmunología , Enfermedades Autoinmunes/patología , Linfocitos B/patología , Proteínas Adaptadoras de Señalización CARD/genética , Proteínas Portadoras/genética , Evolución Clonal/genética , Evolución Clonal/inmunología , Ciclina D3/genética , Guanilato Ciclasa/genética , Humanos , Proteínas Inmediatas-Precoces/genética , Región Variable de Inmunoglobulina/genética , Región Variable de Inmunoglobulina/inmunología , Proteínas Inhibidoras de la Diferenciación/genética , Linfoma/inmunología , Linfoma/patología , Ratones , Mutación/genética , Mutación/inmunología , Proteínas de Neoplasias/genética , Análisis de Secuencia de ADN/métodos , Análisis de Secuencia de ARN/métodos , Análisis de la Célula Individual/métodos , Proteína 3 Inducida por el Factor de Necrosis Tumoral alfa/genética , Proteínas Supresoras de Tumor/genética , Recombinación V(D)J/genéticaRESUMEN
AIMS: Type 2 diabetes (T2D) increases the risk of death associated with cardiovascular complications. However, a complete understanding of protein changes within the diabetic vasculature is still lacking. METHODS: Herein, we utilized mass spectrometry to perform vascular and urinary proteome analysis using a rat model of high-fat feeding and low-dose streptozotocin to simulate late-stage T2D. The purpose of this study was to identify aortic and urine proteins that are differentially expressed in normal and T2D rats. RESULTS: High-fat feeding and low-dose streptozotocin resulted in hyperglycemia, hypoinsulinemia and high levels of circulating free fatty acids. Using a shotgun proteomic approach, high-mobility-group protein B1 and spondin-1 were significantly increased in T2D aorta compared to control aorta, suggesting vascular inflammation and smooth muscle proliferation, respectively. However, the majority of differentially expressed aortic proteins were downregulated in T2D, including proteins associated with coagulation, cell differentiation and redox homeostasis. Strikingly, we report a significant downregulation of commonly used cytoskeletal housekeeping proteins in T2D aorta. Urine from T2D rats displayed increased expression of proteins involved in inflammation and oxidative stress and decreased expression of proteins associated with lipid metabolism and cell adhesion. A number of differentially expressed proteins in urine of T2D rats have previously been reported in human T2D, thereby supporting this animal model as a good representation of human T2D. CONCLUSIONS: Our data offer new information regarding key pathways that could be therapeutically targeted to combat the cardiovascular complications of T2D.
