Ameliorative Effects of Oral Glucosamine on Insulin Resistance and Pancreatic Tissue Damage in Experimental Wistar rats on a High-fat Diet

Glucosamine supplementation contributes to reducing the risk of type 2 diabetes: Evidence from Mendelian randomization combined with a meta-analysis

ObjectiveObservational studies on glucosamine supplementation and type 2 diabetes risk have shown inconsistent results, necessitating the use of Mendelian randomization to clarify the true causal relationship.MethodsThe glucosamine supplementation-related genome-wide association study dataset was obtained from the MRC Integrative Epidemiology Unit consortium, whereas type 2 diabetes-related genome-wide association study datasets were obtained from the FinnGen consortium (discovery) and Xue et al.'s meta-analysis (validation). Two-sample Mendelian randomization analyses were performed separately in the discovery and validation datasets, followed by meta-analysis and multivariable Mendelian randomization analyses to verify the robustness of the results of two-sample Mendelian randomization. The estimation of the causal relationship was conducted through the inverse variance weighted method.ResultsGlucosamine supplementation exhibited a significant protective effect against type 2 diabetes, as identified by two-sample Mendelian randomization analysis in the FinnGen consortium (odds ratio: 0.13, 95% confidence interval: 0.02-0.89) and validated in Xue et al.'s meta-analysis (odds ratio: 0.06, 95%; confidence interval: 0.01-0.29). A combined meta-analysis (odds ratio: 0.08, 95%; confidence interval: 0.02-0.27) of the results of two-sample Mendelian randomization confirmed the robustness of these findings. Additionally, multivariable Mendelian randomization analysis (odds ratio: 0.12, 95%; confidence interval: 0.02-0.94), after adjusting for confounding factors, supported the results of two-sample Mendelian randomization. No evidence of heterogeneity or pleiotropy was observed.ConclusionOverall, our results revealed that genetically predicted glucosamine supplementation was inversely associated with the risk of type 2 diabetes, highlighting the potential importance of glucosamine supplementation in preventing type 2 diabetes.

Genome-Scale Metabolic Modeling of Human Pancreas with Focus on Type 2 Diabetes

Type 2 diabetes (T2D) is characterized by relative insulin deficiency due to pancreatic beta cell dysfunction and insulin resistance in different tissues. Not only beta cells but also other islet cells (alpha, delta, and pancreatic polypeptide [PP]) are critical for maintaining glucose homeostasis in the body. In this overarching context and given that a deeper understanding of T2D pathophysiology and novel molecular targets is much needed, studies that integrate experimental and computational biology approaches offer veritable prospects for innovation. In this study, we report on single-cell RNA sequencing data integration with a generic Human1 model to generate context-specific genome-scale metabolic models for alpha, beta, delta, and PP cells for nondiabetic and T2D states and, importantly, at single-cell resolution. Moreover, flux balance analysis was performed for the investigation of metabolic activities in nondiabetic and T2D pancreatic cells. By altering glucose and oxygen uptakes to the metabolic networks, we documented the ways in which hypoglycemia, hyperglycemia, and hypoxia led to changes in metabolic activities in various cellular subsystems. Reporter metabolite analysis revealed significant transcriptional changes around several metabolites involved in sphingolipid and keratan sulfate metabolism in alpha cells, fatty acid metabolism in beta cells, and myoinositol phosphate metabolism in delta cells. Taken together, by leveraging genome-scale metabolic modeling, this research bridges the gap between metabolic theory and clinical practice, offering a comprehensive framework to advance our understanding of pancreatic metabolism in T2D, and contributes new knowledge toward the development of targeted precision medicine interventions.

Long-term glucosamine supplementation aggravates atrial fibrillation susceptibility by impairing AMPK signaling

AIMS

Glucosamine, a widely used dietary supplement, has been linked to potential cardiovascular risks, including atrial fibrillation (AF). This study aimed to investigate the effects of long-term glucosamine supplementation on AF susceptibility and the underlying mechanisms.

MATERIALS AND METHODS

C57BL/6 J mice were treated with low-dose (15 mg/kg/day) or high-dose (250 mg/kg/day) glucosamine via drinking water for 6 weeks. AF susceptibility was assessed through transesophageal electrical stimulation. Atrial remodeling was characterized through electrophysiological and echocardiography studies, histological analysis, and molecular examination. AMP-activated protein kinase (AMPK) activator 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR) was used to validation the underlying mechanism in mice and isolated neonatal atrial cardiomyocytes.

KEY FINDINGS

Long-term high-dose glucosamine supplementation increased AF susceptibility in mice, as indicated by an elevated AF incidence and duration. Glucosamine induced notable electrical remodeling, evidenced by intra-atrial conduction slowing (P wave duration, amplitude, and area), likely attributable to reduced conduction velocity, as confirmed by two-dimensional electrical mapping. Structural remodeling including increased left atrial weight, cardiomyocyte hypertrophy and fibrosis was evident in the atria of glucosamine-treated mice, despite unaffected cardiac function. Mechanistically, glucosamine suppressed atrial AMPK signaling, leading to lipid and glycogen accumulation. Intriguingly, despite impaired atrial AMPK signaling, high-dose glucosamine improved systemic insulin sensitivity. Pharmacological activation of AMPK with AICAR mitigated glucosamine-induced AF susceptibility and associated pathological changes both in vivo and in vitro.

SIGNIFICANCE

Our findings demonstrate that long-term glucosamine supplementation enhances AF susceptibility, potentially by impairing atrial AMPK signaling, underscoring the importance of caution in the utilization of glucosamine.

Association between intra-pancreatic fat deposition and diseases of the exocrine pancreas: A narrative review

Intrapancreatic fat deposition (IPFD) has garnered increasing attention in recent years. The prevalence of IPFD is relatively high and associated with factors such as obesity, age, and sex. However, the pathophysiological mechanisms underlying IPFD remain unclear, with several potential contributing factors, including oxidative stress, alterations in the gut microbiota, and hormonal imbalances. IPFD was found to be highly correlated with the occurrence and prognosis of exocrine pancreatic diseases. Although imaging techniques remain the primary diagnostic approach for IPFD, an expanding array of biomarkers and clinical scoring systems have been identified for screening purposes. Currently, effective treatments for IPFD are not available; however, existing medications, such as glucagon-like peptide-1 receptor agonists, and new therapeutic approaches explored in animal models have shown considerable potential for managing this disease. This paper reviews the pathogenesis of IPFD, its association with exocrine pancreatic diseases, and recent advancements in its diagnosis and treatment, emphasizing the significant clinical relevance of IPFD.

In-depth investigation of the hypoglycemic mechanism of Morchella importuna polysaccharide via metabonomics combined with 16S rRNA sequencing

Increasing evidence indicates that type 2 diabetes mellitus (T2DM) is closely related to intestinal bacteria disorders and abnormal hepatic metabolism. Morchella importuna polysaccharide (MIP) shows excellent hypoglycemic activity in vitro. However, the hypoglycemic effect and mechanism of MIP in vivo have yet to be investigated. In this study, the blood glucose, blood lipid and insulin resistance of diabetic mice after MIP intervention were measured to evaluate its hypoglycemic effect. Then, the microbiome and metabolomics were combined to explore the hypoglycemic mechanism of MIP. Results indicated that high dose MIP (400 mg/kg) had significant hypoglycemic effect. Furthermore, MIP could reverse diabetes-induced intestinal disorder by increasing the abundance of Akkermansia, Blautia, Dubosiella, and Lachnospiraceae, as well as decreasing the abundance of Helicobacteraceae. Besides, the hepatic metabolites and complex network systems formed by multiple metabolic pathways were regulated after MIP treatment. Notably, a new biomarker of diabetes (N-P-coumaroyl spermidine) was discovered in this study. Moreover, the significant association between intestinal bacteria and hepatic metabolites was determined by correlations analysis, which in turn confirmed MIP alleviated T2DM via the gut-liver axis. Therefore, these findings elucidated in-depth hypoglycemic mechanisms of MIP and provided a new biomarker for the prevention of diabetes.