Influence of cytokine status on insulin resistance and circulating endothelial progenitor cells in type 2 diabetes mellitus

Terminalia catappa Extract Palliates Redox Imbalance and Inflammation in Diabetic Rats by Upregulating Nrf-2 Gene

This study aims at evaluating the ameliorative role of Terminalia catappa aqueous leaf extract (TCA) on hyperglycaemia-induced oxidative stress and inflammation in a high-fat, low dose streptozotocin-induced type 2 diabetic rat model. Experimental rats were treated orally with 400 and 800 mg/kg bw TCA daily for four weeks. Antioxidant enzyme activities, plasma glucose concentration, protein concentration, oxidative stress, and inflammation biomarkers were assayed using standard methods. Hepatic relative expressions of tumour necrosis factor-alpha (TNF-α), interleukin-six (IL-6), and nuclear factor-erythroid 2 related factor 2 (Nrf-2) were also assessed. Molecular docking and prediction of major TCA phytoconstituents' biological activity related to T2DM-induced oxidative stress were evaluated in silico. Induction of diabetes significantly (p < 0.05) reduced superoxide dismutase, glutathione-S-transferase, and peroxidase activities. Glutathione and protein stores were significantly (p < 0.05) depleted, while glucose, MDA, interleukin-six (IL-6), and tumour necrosis factor-α (TNF-α) concentrations were significantly (p < 0.05) increased. A significant (p < 0.05) upregulation of hepatic TNF-α and IL-6 expression and downregulation (p < 0.05) of Nrf-2 expression were observed during diabetes onset. TCA treatment significantly (p < 0.05) modulated systemic diabetic-induced oxidative stress and inflammation, mRNA expression dysregulation, and dysregulated macromolecule metabolism. However, only 800 mg/kg TCA treatment significantly (p < 0.05) downregulated hepatic TNF-α expression. 9-Oxabicyclo[3.3.1]nonane-2,6-diol and 1,2,3-Benzenetriol bound comparably to glibenclamide in Nrf-2, IL-6, and TNF-α binding pockets. They were predicted to be GST A and M substrate, JAK2 expression, ribulose-phosphate 3-epimerase, NADPH peroxidase, and glucose oxidase inhibitors. These results suggest that TCA ameliorates hyperglycaemia-induced oxidative stress and inflammation by activating Nrf-2 gene.

Stromal cell-derived factor-1 may play pivotal role in distraction-stimulated neovascularization of diabetic foot ulcer

Diabetic foot ulcer (DFU) has become a major medical, social and economic concern worldwide. It is highly desirable to develop promising new solutions to effectively and appropriately treat DFU. In recent years, investigators have used an innovative technology called proximal tibial cortex transverse distraction (PTCTD) to treat DFU and have achieved satisfactory results in terms of improved wound healing and circumvention of amputation as a consequence of enhanced neovascularization and perfusion of the ulcerated feet after the operation, but the underlying mechanism has not been explored. Previous studies have suggested that in addition to stimulating osteogenesis, bone distraction also facilitates neovascularization, which may be associated with the chemokine stromal cell-derived factor-1 (SDF-1). As an important member of the chemokine family, SDF-1 is primarily responsible for the homing and migration of endothelial progenitor cells (EPCs) or bone marrow-derived mesenchymal stem cells (BMSCs), and plays a central role in the process of neovascularization. In vivo or in vitro experiments show that bone distraction can induce the expression of SDF-1 and increase its plasma concentration. Moreover, some researchers have found that an insufficient level of SDF-1 in the circulation and wounds of patients with DFU can lead to impaired neovascularization. Therefore, we believe that SDF-1 plays an important role in promoting neovascularization of DFU as a result of bone distraction. We summarize the currently relevant literature to put forward an undisclosed but meaningful mechanism of bone distraction in the treatment of DFU.

hsa_circ_0058092 protects against hyperglycemia‑induced endothelial progenitor cell damage via miR‑217/FOXO3

Circular RNAs (circRNAs) regulate the expression of genes that are critical for various biological and pathological processes. Previous studies have reported that the expression of hsa_circ_0058092 is decreased in patients with diabetes mellitus (DM); however, the specific role of this circRNA in DM is unknown. In the present study, endothelial progenitor cells (EPCs) were isolated and a decreased hsa_circ_0058092 expression was found under conditions of hyperglycemia (HG). The overexpression of hsa_circ_0058092 protected the EPCs against HG‑induced damage by preserving cell survival, proliferation, migration and angiogenic differentiation. The overexpression of hsa_circ_0058092 also decreased the HG‑induced increase in NADPH‑oxidase proteins and inflammatory cytokines. Further investigation revealed that the overexpression of hsa_circ_0058092 enhanced FOXO3 expression, which was mediated through the interaction with miR‑217. Furthermore, the upregulation of miR‑217 or the downregulation of FOXO3 abolished the protective effects of hsa_circ_0058092 against HG‑induced EPC damage. On the whole, these data suggest that hsa_circ_0058092 acts via the miR‑217/FOXO3 pathway to protect against EPCs HG‑induced damage, and to preserve the migration and angiogenesis of EPCs.

Vitamin D (1,25-(OH)2D3) regulates the gene expression through competing endogenous RNAs networks in high glucose-treated endothelial progenitor cells

Vitamin D (vit-D) supplementation can improve endothelial cell function in type 2 diabetes mellitus patients with vit-D insufficiency or deficiency. In the present study, we aimed to compare the expression profiles of circRNAs, lncRNAs, miRNAs, and mRNAs between 1,25-(OH)₂D₃-treated endothelial progenitor cells (EPCs) and control cells, and to further construct the 1,25-(OH)₂D₃-regulated ceRNA networks in EPCs. RNA sequencing was performed on the 1,25-(OH)₂D₃-treated EPCs and control cells derived from the bone marrow (BM). Bioinformatics analyses were performed to identify differentially expressed (DE) microRNAs (miRNAs), circular RNAs (circRNAs), mRNAs, and long non-coding RNAs (lncRNAs). Then Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted to predict the function of genes. Competing endogenous RNA (ceRNA) networks were constructed with Cytoscape software. 1,25-(OH)₂D₃ application induced changes in the expression profiles of 1791 mRNAs, 2726 lncRNAs, 205 circRNAs, and 45 miRNAs in EPCs treated with high levels of glucose. These DE RNAs were associated with MMP and GTPase activities, specific signaling pathways, and components of actin, extracellular matrix, or adherens junction. DE circRNAs, which functioned independently of their linear host genes, interacted with miRNAs to serve as miRNA sponges in complex ceRNA networks. The data indicated that circRNAs and lncRNAs comprised ceRNAs to sponge effects of miRNAs on the expressions of mRNAs following 1,25-(OH)₂D₃ application in EPCs. 1,25-(OH)₂D₃ improved the function of EPCs via associated ceRNA interaction networks in diabetes patients.