Exercise activates AMPK in mouse and human pancreatic islets to decrease senescence

Exercise-induced meteorin-like protein protects human pancreatic beta cells from cytokine-induced apoptosis

AIMS/HYPOTHESIS

Inflammation-driven pancreatic beta cell death is a hallmark of type 1 diabetes progression. We have previously shown that serum obtained from individuals after high-intensity interval training prevents cytokine-induced human beta cell apoptosis, but the mediators of this beneficial effect remain to be characterised. In this study we evaluated the role of exercise-induced meteorin-like protein (Metrnl) in human beta cell protection.

METHODS

Human EndoC-βH1 cells and induced pluripotent stem cell (iPSC)-derived islets were exposed to proinflammatory cytokines and treated with serum collected before and after high-intensity interval training, with and without Metrnl-neutralising antibodies. The effects of Metrnl on apoptosis, insulin secretion and chemokine CXCL10 gene and protein expression were assessed.

RESULTS

Post-exercise serum had an increased concentration of Metrnl compared with pre-exercise level serum, resulting in a 46% reduction in cytokine-induced beta cell death. Additionally, direct treatment with recombinant Metrnl at concentrations of 100 ng/ml and 200 ng/ml reduced cytokine-induced cell death by 24% and 41%, respectively, in EndoC-βH1 cells, with similar results obtained in iPSC-derived islets. Metrnl treatment also preserved insulin secretion under inflammatory stress. These effects were associated with a decrease in CXCL10 mRNA expression and protein release. Blocking Metrnl with a neutralising antibody eliminated the protective effects of serum from trained individuals on EndoC-βH1 cells exposure to proinflammatory cytokines.

CONCLUSIONS/INTERPRETATION

Our findings reveal that the exerkine Metrnl is a key mediator of the beneficial effects of exercise on pancreatic beta cells, suggesting that Metrnl is a potential therapeutic target for preserving human beta cell function and survival in type 1 diabetes.

Polyphenol extracts from rambutan peel promote longevity via the attenuation of the Toll/Imd pathway

Rambutan peel is rich in polyphenols such as ellagic acid, corilagin, geraniin, quercetin, and rutin, which contribute to its diverse health benefits, including antioxidant, antimicrobial, antiviral, anti-inflammatory, hypoglycemic, and potential anticancer properties. The polyphenols present in the rambutan peel demonstrate potential for delaying cellular aging by mitigating oxidative stress within cells. Moreover, no study has systematically explored the anti-aging effects and the underlying mechanisms of polyphenols derived from rambutan peel. Drosophila melanogaster has often been used in aging studies to reveal the mechanisms of aging onset and development. Using Drosophila melanogaster as an in vivo aging model, the aim of the present study was to probe whether rambutan peel polyphenol extracts (RPPEs) exert a lifespan extending effect in vivo and to gain insights into the mechanism of action. Results highlighted that the optimized concentration of RPPEs for the anti-aging treatment in Drosophila melanogaster was 5 mg mL-1. In addition, RPPEs extended the lifespan of Drosophila melanogaster in a manner that was related to the dose and gender. Meanwhile, RPPEs improved the climbing ability and sleep and maintained the antioxidant capacity of aged Drosophila. RPPEs also ameliorated intestinal barrier damage in aging Drosophila. Transcriptome sequencing analysis showed that RPPEs extended the lifespan of Drosophila by down-regulating the Toll/IMD signaling pathway.

Single-cell decoding of human islet cell type-specific alterations in type 2 diabetes reveals converging genetic- and state-driven β -cell gene expression defects

Pancreatic islets maintain glucose homeostasis through coordinated action of their constituent endocrine and affiliate cell types and are central to type 2 diabetes (T2D) genetics and pathophysiology. Our understanding of robust human islet cell type-specific alterations in T2D remains limited. Here, we report comprehensive single cell transcriptome profiling of 245,878 human islet cells from a 48-donor cohort spanning non-diabetic (ND), pre-diabetic (PD), and T2D states, identifying 14 distinct cell types detected in every donor from each glycemic state. Cohort analysis reveals ~25-30% loss of functional beta cell mass in T2D vs. ND or PD donors resulting from (1) reduced total beta cell numbers/proportions and (2) reciprocal loss of 'high function' and gain of senescent β -cell subpopulations. We identify in T2D β -cells 511 differentially expressed genes (DEGs), including new (66.5%) and validated genes (e.g., FXYD2, SLC2A2, SYT1), and significant neuronal transmission and vitamin A metabolism pathway alterations. Importantly, we demonstrate newly identified DEG roles in human β -cell viability and/or insulin secretion and link 47 DEGs to diabetes-relevant phenotypes in knockout mice, implicating them as potential causal islet dysfunction genes. Additionally, we nominate as candidate T2D causal genes and therapeutic targets 27 DEGs for which T2D genetic risk variants (GWAS SNPs) and pathophysiology (T2D vs. ND) exert concordant expression effects. We provide this freely accessible atlas for data exploration, analysis, and hypothesis testing. Together, this study provides new genomic resources for and insights into T2D pathophysiology and human islet dysfunction.