Circulating miR-146a in healthy aging and type 2 diabetes: Age- and gender-specific trajectories

Plasma levels of interleukin-38 in healthy aging and in type 2 diabetes

Plasma levels of interleukin (IL)-38 were evaluated in patients with type 2 diabetes (T2DM) and healthy controls. Plasma IL-38 was higher in T2DM patients and positively related to waist/hip ratio, HbA1c, uric acid, liver function tests, triglycerides and total proteins. Patients suffering from diabetic nephropathy had the highest IL-38 levels.

Long-term exposure of human endothelial cells to metformin modulates miRNAs and isomiRs

Increasing evidence suggest that the glucose-lowering drug metformin exerts a valuable anti-senescence role. The ability of metformin to affect the biogenesis of selected microRNAs (miRNAs) was recently suggested. MicroRNA isoforms (isomiRs) are distinct variations of miRNA sequences, harboring addition or deletion of one or more nucleotides at the 5′ and/or 3′ ends of the canonical miRNA sequence. We performed a comprehensive analysis of miRNA and isomiR profile in human endothelial cells undergoing replicative senescence in presence of metformin. Metformin treatment was associated with the differential expression of 27 miRNAs (including miR-100-5p, -125b-5p, -654-3p, -217 and -216a-3p/5p). IsomiR analysis revealed that almost 40% of the total miRNA pool was composed by non-canonical sequences. Metformin significantly affects the relative abundance of 133 isomiRs, including the non-canonical forms of the aforementioned miRNAs. Pathway enrichment analysis suggested that pathways associated with proliferation and nutrient sensing are modulated by metformin-regulated miRNAs and that some of the regulated isomiRs (e.g. the 5′ miR-217 isomiR) are endowed with alternative seed sequences and share less than half of the predicted targets with the canonical form. Our results show that metformin reshapes the senescence-associated miRNA/isomiR patterns of endothelial cells, thus expanding our insight into the cell senescence molecular machinery.

Decreased serum levels of the inflammaging marker miR-146a are associated with clinical non-response to tocilizumab in COVID-19 patients

Current COVID-19 pandemic poses an unprecedented threat to global health and healthcare systems. The most amount of the death toll is accounted by old people affected by age-related diseases that develop a hyper-inflammatory syndrome. In this regard, we hypothesized that COVID-19 severity may be linked to inflammaging. Here, we examined 30 serum samples from patients enrolled in the clinical trial NCT04315480 assessing the clinical response to a single-dose intravenous infusion of the anti-IL-6 receptor drug Tocilizumab (TCZ) in COVID-19 patients with multifocal interstitial pneumonia.

In these serum samples, as well as in 29 age- and gender-matched healthy control subjects, we assessed a set of microRNAs that regulate inflammaging, i.e. miR-146a-5p, miR-21-5p, and miR-126-3p, which were quantified by RT-PCR and Droplet Digital PCR.

We showed that COVID-19 patients who did not respond to TCZ have lower serum levels of miR-146a-5p after the treatment (p = 0.007). Among non-responders, those with the lowest serum levels of miR-146a-5p experienced the most adverse outcome (p = 0.008). Our data show that a blood-based biomarker, such as miR-146a-5p, can provide clues about the molecular link between inflammaging and COVID-19 clinical course, thus allowing to better understand the use of biologic drug armory against this worldwide health threat.

Metformin decreases miR-122, miR-223 and miR-29a in women with polycystic ovary syndrome

Metformin is associated with increased insulin sensitivity, whereas oral contraceptive pills (OCP) could increase the risk for type 2 diabetes (T2D) in women with polycystic ovary syndrome (PCOS). Certain miRNAs might serve as biomarkers for the risk of T2D. The aim of this study was to investigate changes in circulating miRNA levels during treatment with metformin and OCP in women with PCOS. Sixty-five women with PCOS according to Rotterdam criteria were randomized to metformin (2 g/day), metformin + OCP (150 mg desogestrel + 30 µg ethinylestradiol) or OCP alone for 12 months. Serum miRNA analysis was performed with individual RT-qPCR or Taqman low density array cards of 22 selected miRNAs previously related to PCOS, glucose and/or lipid metabolism. miR-122 and miR-29a levels were decreased after treatment with metformin compared with metformin + OCP and OCP group: miR-122: log2 difference -0.7 (P = 0.01) and -0.7 (P = 0.02), miR-29a: log2 difference -0.5 (P = 0.01) and -0.4 (P = 0.04), while miR-223 levels were decreased in the metformin + OCP group after treatment: log2 difference -0.5 (P = 0.02). During the treatment period, a significant weight loss was observed in the metformin group compared with the OCP group. In the OCP group, miRNA levels were unchanged during the treatment period. Levels of circulating miRNAs associated with lipid and glucose metabolism decreased during metformin treatment. Changes in miRNA levels in the metformin group could be explained by the simultaneous weight loss in the same group. These results support the notion that metformin treatment alone may be superior for metabolic health compared with OCP.

Disease-specific plasma levels of mitokines FGF21, GDF15, and Humanin in type II diabetes and Alzheimer's disease in comparison with healthy aging

Fibroblast Growth Factor 21 (FGF21), Growth Differentiation Factor 15 (GDF15), and Humanin (HN) are mitochondrial stress-related mitokines, whose role in health and disease is still debated. In this study, we confirmed that their plasma levels are positively correlated with age in healthy subjects. However, when looking at patients with type 2 diabetes (T2D) or Alzheimer's disease (AD), two age-related diseases sharing a mitochondrial impairment, we found that GDF15 is elevated in T2D but not in AD and represents a risk factor for T2D complications, while FGF21 and HN are lower in AD but not in T2D. Moreover, FGF21 reaches the highest levels in centenarian' offspring, a model of successful aging. As a whole, these data indicate that (i) the adaptive mitokine response observed in healthy aging is lost in age-related diseases, (ii) a common expression pattern of mitokines does not emerge in T2D and AD, suggesting an unpredicted complexity and disease-specificity, and (iii) FGF21 emerges as a candidate marker of healthy aging.

Gerobiotics: probiotics targeting fundamental aging processes

Aging is recognized as a common risk factor for many chronic diseases and functional decline. The newly emerging field of geroscience is an interdisciplinary field that aims to understand the molecular and cellular mechanisms of aging. Several fundamental biological processes have been proposed as hallmarks of aging. The proposition of the geroscience hypothesis is that targeting holistically these highly integrated hallmarks could be an effective approach to preventing the pathogenesis of age-related diseases jointly, thereby improving the health span of most individuals. There is a growing awareness concerning the benefits of the prophylactic use of probiotics in maintaining health and improving quality of life in the elderly population. In view of the rapid progress in geroscience research, a new emphasis on geroscience-based probiotics is in high demand, and such probiotics require extensive preclinical and clinical research to support their functional efficacy. Here we propose a new term, "gerobiotics", to define those probiotic strains and their derived postbiotics and para-probiotics that are able to beneficially attenuate the fundamental mechanisms of aging, reduce physiological aging processes, and thereby expand the health span of the host. We provide a thorough discussion of why the coining of a new term is warranted instead of just referring to these probiotics as anti-aging probiotics or with other similar terms. In this review, we highlight the needs and importance of the new field of gerobiotics, past and currently on-going research and development in the field, biomarkers for potential targets, and recommended steps for the development of gerobiotic products. Use of gerobiotics could be a promising intervention strategy to improve health span and longevity of humans in the future.

A comparative study on the cellular stressors in mesenchymal stem cells (MSCs) and pancreatic β-cells under hyperglycemic milieu

β-cell dysfunction is a critical determinant for both type 1 diabetes and type 2 diabetes and β-cells are shown to be highly susceptible to cellular stressors. Mesenchymal stem cells (MSCs) on the other hand are known to have immunomodulatory potential and preferred in clinical applications. However, there is paucity of a comparative study on these cells in relation to several cellular stressors in response to hyperglycemia and this forms the rationale for the present study. INS1 β-cells and MSCs were subjected to high-glucose treatment without and with Metformin, Lactoferrin, or TUDCA and assessed for stress signaling alterations using gene expression, protein expression, as well as functional read-outs. Compared to the untreated control cells, INS1 β-cells or MSCs treated with high glucose showed significant increase in mRNA expressions of ER stress, senescence, and proinflammation. This was accompanied by increased miR146a target genes and decreased levels of SIRT1, NRF2, and miR146a in both the cell types. Consistent with the mRNA results, protein expression levels do reflect the same alterations. Notably, the alterations are relatively less extent in MSCs compared to INS1 β-cells. Interestingly, three different agents, viz., Metformin, Lactoferrin, or TUDCA, were found to overcome the high glucose-induced cellular stresses in a concerted and inter-linked way and restored the proliferation and migration capacity in MSCs as well as normalized the glucose-stimulated insulin secretion in INS1 β-cells. While our study gives a directionality for potential supplementation of metformin/lactoferrin/TUDCA in optimization protocols of MSCs, we suggest that in vitro preconditioning of MSCs with such factors should be further explored with in-depth investigations to harness and enhance the therapeutic capacity/potential of MSCs.

RNA-Seq Revealed Novel Non-proliferative Retinopathy Specific Circulating MiRNAs in T2DM Patients

Background: Diabetic retinopathy (DR) is a common diabetes complication and was considered as the major cause of blindness among young adults. MiRNAs are a group of small non-coding RNAs regulating the expression of target genes and have been reported to be associated with the development of DR in a variety of molecular mechanisms. In this study, we aimed to identify miRNAs that are differentially expressed (DE) in the serum of DR patients. Methods: We recruited 21 type 2 diabetes mellitus (T2DM) inpatients of Chinese Han ancestry, consisting of 10 non-proliferative DR patients (DR group) and 11 non-DR T2DM patients (NDR group). MiRNA was extracted from fasting peripheral serum and quantified by RNA-seq. The expression levels of miRNA were evaluated and compared between the two groups, with adjustments made for age differences. The validated target genes of miRNAs were subjected to a pathway analysis. We also constructed a weighted polygenic risk score using the DE miRNA and evaluated its predictive power. Results: Five miRNAs were DE between DR and NDR groups (p-Value ≤ 0.01, LFC ≥ 2 or LFC ≤-2). These included miR-4448, miR-338-3p, miR-190a-5p, miR-485-5p, and miR-9-5p. In total, these miRNAs were validated to regulate 55 target genes. Four target genes were found to overlap with the NAD metabolism, sirtuin, and aging pathway, which was thought to control the vascular growth and morphogenesis. The predictive power of our polygenic risk score was apparently high (AUC = 0.909). However, it needs to be interpreted with caution. Conclusion: In this study, we discovered novel DR-specific miRNAs in human serum samples. These circulating miRNAs may represent the pathological changes in the retina in response to diabetes and may serve as non-invasive biomarkers for early DR risk prediction.