Hyperinsulinemia Is Highly Associated With Markers of Hepatocytic Senescence in Two Independent Cohorts

Metabolic dysfunction-associated liver disease and diabetes: Matrix remodeling, fibrosis, and therapeutic implications

Metabolic dysfunction-associated liver disease (MASLD) and steatohepatitis (MASH) are becoming the most common causes of chronic liver disease in the United States and worldwide due to the obesity and diabetes epidemics. It is estimated that by 2030 close to 100 million people might be affected and patients with type 2 diabetes are especially at high risk. Twenty to 30% of patients with MASLD can progress to MASH, which is characterized by steatosis, necroinflammation, hepatocyte ballooning, and in advanced cases, fibrosis progressing to cirrhosis. Clinically, it is recognized that disease progression in diabetic patients is accelerated and the role of various genetic and epigenetic factors, as well as cell-matrix interactions in fibrosis and stromal remodeling, have recently been recognized. While there has been great progress in drug development and clinical trials for MASLD/MASH, the complexity of these pathways highlights the need to improve diagnosis/early detection and develop more successful antifibrotic therapies that not only prevent but reverse fibrosis.

Prepared Radix Polygoni Multiflori and emodin alleviate lipid droplet accumulation in nonalcoholic fatty liver disease through MAPK signaling pathway inhibition

As one of the most common liver diseases, nonalcoholic fatty liver disease (NAFLD) affects almost one-quarter of the world's population. Although the prevalence of NAFLD is continuously rising, effective medical treatments are still inadequate. Radix Polygoni Multiflori (RPM) is a traditional Chinese herbal medicine. As a processed product of RPM, prepared Radix Polygoni Multiflori (PRPM) has been reported to have antioxidant and anti-inflammatory effects. This study investigated whether PRPM treatment could significantly improve NAFLD. We used recent literature, the Herb database and the SwissADME database to isolate the active compounds of PRPM. The OMIM, DisGeNET and GeneCards databases were used to isolate NAFLD-related target genes, and GO functional enrichment and KEGG pathway enrichment analyses were conducted. Moreover, PRPM treatment in NAFLD model mice was evaluated. The results indicate that the target genes are mainly enriched in the AMPK and de novo lipogenesis signaling pathways and that PRPM treatment improves NAFLD disease in model mice. Here, we found the potential benefits of PRPM against NAFLD and demonstrated in vivo and in vitro that PRPM and its ingredient emodin downregulate phosphorylated P38/P38, phosphorylated ERK1/2 and genes related to de novo adipogenesis signaling pathways and reduce lipid droplet accumulation. In conclusion, our findings revealed a novel therapeutic role for PRPM in the treatment of NAFLD and metabolic inflammation.

Insulin and aging - a disappointing relationship

Experimental studies in animal models of aging such as nematodes, fruit flies or mice have observed that decreased levels of insulin or insulin signaling promotes longevity. In humans, hyperinsulinemia and concomitant insulin resistance are associated with an elevated risk of age-related diseases suggestive of a shortened healthspan. Age-related disorders include neurodegenerative diseases, hypertension, cardiovascular disease, and type 2 diabetes. High ambient insulin concentrations promote increased lipogenesis and fat storage, heightened protein synthesis and accumulation of non-functional polypeptides due to limited turnover capacity. Moreover, there is impaired autophagy activity, and less endothelial NO synthase activity. These changes are associated with mitochondrial dysfunction and oxidative stress. The cellular stress induced by anabolic activity of insulin initiates an adaptive response aiming at maintaining homeostasis, characterized by activation of the transcription factor Nrf2, of AMP activated kinase, and an unfolded protein response. This protective response is more potent in the long-lived human species than in short-lived models of aging research resulting in a stronger pro-aging impact of insulin in nematodes and fruit flies. In humans, resistance to insulin-induced cell stress decreases with age, because of an increase of insulin and insulin resistance levels but less Nrf2 activation. These detrimental changes might be contained by adopting a lifestyle that promotes low insulin/insulin resistance levels and enhances an adaptive response to cellular stress, as observed with dietary restriction or exercise.

Increased cell senescence in human metabolic disorders

Cell senescence (CS) is at the nexus between aging and associated chronic disorders, and aging increases the burden of CS in all major metabolic tissues. However, CS is also increased in adult obesity, type 2 diabetes (T2D), and nonalcoholic fatty liver disease independent of aging. Senescent tissues are characterized by dysfunctional cells and increased inflammation, and both progenitor cells and mature, fully differentiated and nonproliferating cells are afflicted. Recent studies have shown that hyperinsulinemia and associated insulin resistance (IR) promote CS in both human adipose and liver cells. Similarly, increased CS promotes cellular IR, showing their interdependence. Furthermore, the increased adipose CS in T2D is independent of age, BMI, and degree of hyperinsulinemia, suggesting premature aging. These results suggest that senomorphic/senolytic therapy may become important for treating these common metabolic disorders.

Senescent Cells: A Therapeutic Target in Cardiovascular Diseases

Senescent cell accumulation has been observed in age-associated diseases including cardiovascular diseases. Senescent cells lack proliferative capacity and secrete senescence-associated secretory phenotype (SASP) factors that may cause or worsen many cardiovascular diseases. Therapies targeting senescent cells, especially senolytic drugs that selectively induce senescent cell removal, have been shown to delay, prevent, alleviate, or treat multiple age-associated diseases in preclinical models. Some senolytic clinical trials have already been completed or are underway for a number of diseases and geriatric syndromes. Understanding how cellular senescence affects the various cell types in the cardiovascular system, such as endothelial cells, vascular smooth muscle cells, fibroblasts, immune cells, progenitor cells, and cardiomyocytes, is important to facilitate translation of senotherapeutics into clinical interventions. This review highlights: (1) the characteristics of senescent cells and their involvement in cardiovascular diseases, focusing on the aforementioned cardiovascular cell types, (2) evidence about senolytic drugs and other senotherapeutics, and (3) the future path and clinical potential of senotherapeutics for cardiovascular diseases.

Short-term physical exercise controls age-related hyperinsulinemia and improves hepatic metabolism in aged rodents

PURPOSE

Aging is associated with changes in glucose homeostasis related to both decreased insulin secretion and/or impaired insulin action, contributing to the high prevalence of type 2 diabetes (T2D) in the elderly population. Additionally, studies are showing that chronically high levels of circulating insulin can also lead to insulin resistance. In contrast, physical exercise has been a strategy used to improve insulin sensitivity and metabolic health. However, the molecular alterations resulting from the effects of physical exercise in the liver on age-related hyperinsulinemia conditions are not yet fully established. This study aimed to investigate the effects of 7 days of aerobic exercise on hepatic metabolism in aged hyperinsulinemic rats (i.e., Wistar and F344) and in Slc2a4^+/- mice (hyperglycemic and hyperinsulinemic mice).

RESULTS

Both aged models showed alterations in insulin and glucose tolerance, which were associated with essential changes in hepatic fat metabolism (lipogenesis, gluconeogenesis, and inflammation). In contrast, 7 days of physical exercise was efficient in improving whole-body glucose and insulin sensitivity, and hepatic metabolism. The Slc2a4^+/- mice presented significant metabolic impairments (insulin resistance and hepatic fat accumulation) that were improved by short-term exercise training. In this scenario, high circulating insulin may be an important contributor to age-related insulin resistance and hepatic disarrangements in some specific conditions.

CONCLUSION

In conclusion, our data demonstrated that short-term aerobic exercise was able to control mechanisms related to hepatic fat accumulation and insulin sensitivity in aged rodents. These effects could contribute to late-life metabolic health and prevent the development/progression of age-related T2D.

Targeting nonalcoholic fatty liver disease via gut microbiome-centered therapies

Humans possess abundant amounts of microorganisms, including bacteria, fungi, viruses, and archaea, in their gut. Patients with nonalcoholic fatty liver disease (NAFLD) exhibit alterations in their gut microbiome and an impaired gut barrier function. Preclinical studies emphasize the significance of the gut microbiome in the pathogenesis of NAFLD. In this overview, we explore how adjusting the gut microbiome could serve as an innovative therapeutic strategy for NAFLD. We provide a summary of current information on untargeted techniques such as probiotics and fecal microbiota transplantation, as well as targeted microbiome-focused therapies including engineered bacteria, prebiotics, postbiotics, and phages for the treatment of NAFLD.

Targeting cellular senescence in metabolic disease

Cellular senescence is a cell fate involving cell cycle arrest, resistance against apoptosis, and the development of a secretome that can be pro-inflammatory. In aging and obesity, senescent cells accumulate in many tissues, including adipose tissue, brain, kidney, pancreas, and liver. These senescent cells and their downstream effects appear to perpetuate inflammation and have been implicated in the pathogenesis of metabolic dysfunction. Senescent cells are cleared in part by the immune system, a process that is diminished in obesity and aging, likely due in part to senescence of immune cells themselves. Targeting senescent cells or their products improves metabolic function in both aging and in animal models of obesity. Novel therapeutics to target senescent cells are on the horizon and are currently being investigated in clinical trials in humans for multiple diseases. Early evidence suggests that senolytic drugs, which transiently disarm the anti-apoptotic defenses of pro-inflammatory senescent cells, are effective in causing depletion of senescent cells in humans. Senescence-targeting therapeutics, including senolytic drugs and strategies to increase immune clearance of senescent cells, hold significant promise for treating metabolic dysfunction in multiple tissues and disease states.

Identification and Development of an Age-Related Classification and Signature to Predict Prognosis and Immune Landscape in Osteosarcoma

Background. In childhood and adolescence, the prevailing bone tumor is osteosarcoma associated with frequent recurrence and lung metastasis. This research focused on predicting the survival and immune landscape of osteosarcoma by developing a prognostic signature and establishing aging-related genes (ARGs) subtypes. Methods. The training group comprised of the transcriptomic and associated clinical data of 84 patients with osteosarcoma accessed at the TARGET database and the validation group consisted of 53 patients from GSE21257. The aging-related subtypes were identified using unsupervised consensus clustering analysis. The ARG signature was developed utilizing multivariate Cox analysis and LASSO regression. The prognostic value was assessed using the univariate and multivariate Cox analyses, Kaplan-Meier plotter, time-dependent ROC curve, and nomogram. The functional enrichment analyses were performed by GSEA, GO, and KEGG analysis, while the ssGSEA, ESTIMATE, and CIBERSORT analyses were conducted to reveal the immune landscape in osteosarcoma. Results. The two clusters of osteosarcoma patients formed based on 543 ARGs, depicted a considerable difference in the tumor microenvironment, and the overall survival and immune cell infiltration rate varied as well. Among these, the selected 23 ARGs were utilized for the construction of an efficient predictive prognostic signature for the overall survival prediction. The testing in the validation group of osteosarcoma patients confirmed the status of the high-risk score as an independent indicator for poor prognosis, which was already identified as such using the univariate and multivariate Cox analyses. Furthermore, the ARG signature could distinguish different immune-related functions, infiltration status of immune cells, and tumor microenvironment, as well as predict the immunotherapy response of osteosarcoma patients. Conclusion. The aging-related subtypes were identified and a prognostic signature was developed in this research, which determined different prognoses and allowed for treatment of osteosarcoma patients to be tailored. Additionally, the immunotherapeutic response of individuals with osteosarcoma could also be predicted by the ARG signature.