thymosin and Diabetes-Mellitus--Type-2

Prior studies show that signature phenotypes of diabetic human induced pluripotent stem cells derived endothelial cells (dia-hiPSC-ECs) are disrupted glycine homeostasis, increased senescence, impaired mitochondrial function and angiogenic potential as compared with healthy hiPSC-ECs. In the current study, we aimed to assess the role of thymosin β-4 (Tb-4) on endothelial function using dia-hiPSC-ECs as disease model of endothelial dysfunction.. Using dia-hiPSC-ECs as models of endothelial dysfunction, we determined the effect of Tb-4 on cell proliferation, senescence, cyto-protection, protein expression of intercellular adhesion molecule-1 (ICAM-1), secretion of endothelin-1 and MMP-1, mitochondrial membrane potential, and cyto-protection in vitro and angiogenic potential for treatment of ischemic limb disease in a mouse model of type 2 diabetes mellitus (T2DM) in vivo. We found that 600 ng/mL Tb4 significantly up-regulated AKT activity and Bcl-XL protein expression, enhanced dia-hiPSC-EC viability and proliferation, limited senescence, reduced endothelin-1 and MMP-1 secretion, and improved reparative potency of dia-hiPSC-ECs for treatment of ischemic limb disease in mice with T2DM. However, Tb4 had no effect on improving mitochondrial membrane potential and glycine homeostasis and reducing intercellular adhesion molecule-1 protein expression in dia-hiPSC-ECs.. Tb-4 improves endothelial dysfunction through enhancing hiPSC-EC viability, reducing senescence and endothelin-1 production, and improves angiogenic potency in diabetes.

Topics: Animals; Cell Differentiation; Diabetes Mellitus, Type 2; Endothelial Cells; Humans; Induced Pluripotent Stem Cells; Mice; Thymosin

Skeletal muscle is an endocrine organ secreting exercise-induced factors (exerkines), which play a pivotal role in interorgan cross talk. Using mass spectrometry (MS)-based proteomics, we characterized the secretome and identified thymosin β4 (TMSB4X) as the most upregulated secreted protein in the media of contracting C2C12 myotubes. TMSB4X was also acutely increased in the plasma of exercising humans irrespective of the insulin resistance condition or exercise mode. Treatment of mice with TMSB4X did not ameliorate the metabolic disruptions associated with diet induced-obesity, nor did it enhance muscle regeneration in vivo. However, TMSB4X increased osteoblast proliferation and neurite outgrowth, consistent with its WADA classification as a prohibited growth factor. Therefore, we report TMSB4X as a human exerkine with a potential role in cellular cross talk.

Topics: Animals; Case-Control Studies; Cell Line, Tumor; Cell Proliferation; Diabetes Mellitus, Type 2; Disease Models, Animal; Humans; Insulin Resistance; Male; Mice, Inbred C57BL; Muscle Contraction; Muscle Fibers, Skeletal; Muscle, Skeletal; Muscular Diseases; Neuronal Outgrowth; Osteoblasts; Physical Endurance; Proteomics; Signal Transduction; Tandem Mass Spectrometry; Thymosin

Topics: Animals; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diabetic Neuropathies; Disease Models, Animal; Endothelial Cells; Ganglia, Spinal; Interleukin-1 Receptor-Associated Kinases; Male; Mice; Mice, Transgenic; MicroRNAs; Neuronal Outgrowth; NF-kappa B; Sciatic Nerve; Signal Transduction; Thymosin; TNF Receptor-Associated Factor 6

Peripheral neuropathy is a chronic complication of diabetes mellitus. To investigated the efficacy and safety of the extended treatment of diabetic peripheral neuropathy with thymosin β4 (Tβ4), male diabetic mice (db/db) at the age of 24 weeks were treated with Tβ4 or saline for 16 consecutive weeks. Treatment of diabetic mice with Tβ4 significantly improved motor (MCV) and sensory (SCV) conduction velocity in the sciatic nerve and the thermal and mechanical latency. However, Tβ4 treatment did not significantly alter blood glucose levels. Treatment with Tβ4 significantly increased intraepidermal nerve fiber density. Furthermore, Tβ4 counteracted the diabetes-induced axon diameter and myelin thickness reductions and the g-ratio increase in sciatic nerve. In vitro, compared with dorsal root ganglia (DRG) neurons derived from nondiabetic mice, DRG neurons derived from diabetic mice exhibited significantly decreased neurite outgrowth, whereas Tβ4 promoted neurite growth in these diabetic DRG neurons. Blockage of the Ang1/Tie2 signaling pathway with a neutralized antibody against Tie2 abolished Tβ4-increased neurite outgrowth. Our data demonstrate that extended Tβ4 treatment ameliorates diabetic-induced axonal degeneration and demyelination, which likely contribute to therapeutic effect of Tβ4 on diabetic neuropathy. The Ang1/Tie2 pathway may mediate Tβ4-induced axonal remodeling.

Topics: Animals; Blood Glucose; Diabetes Mellitus, Type 2; Diabetic Neuropathies; Disease Models, Animal; Ganglia, Spinal; Male; Mice; Nerve Fibers; Sciatic Nerve; Signal Transduction; Thymosin; Treatment Outcome

Prothymosin-α (ProT) is involved in oxidative stress, inflammation, cell proliferation, and apoptosis. Increased oxidative stress and chronic inflammation participate in the pathogenesis of diabetes. A recent study found that ProT is a ligand of toll-like receptor 4, which plays an important role in the development of insulin resistance. However, its physiological role remains poorly understood.. The objective was to investigate whether ProT contributes to the development of insulin resistance.. A total of 185 subjects were recruited and classified into nondiabetes (n = 95) and newly diagnosed diabetes (n = 90) groups. Transgenic mice overexpressing ProT were used to investigate the role of ProT in the development of insulin resistance. Lentiviral vectors carrying short hairpin RNA specific for ProT were delivered via the portal vein to silence hepatic ProT expression in mice with high-fat diet-induced insulin resistance. Glucose uptake was determined in L6 myotubes.. We show that the serum ProT levels of patients with type 2 diabetes were significantly higher than those of normal individuals (mean ± SEM, 419.8 ± 46.47 vs 246.4 ± 27.89 pg/mL; P < .001). Furthermore, ProT transgenic mice exhibited an insulin-resistant phenotype, whereas the silencing of hepatic ProT expression ameliorated high-fat diet-induced insulin resistance in C57BL/6 mice. In vitro studies reveal that ProT induced insulin resistance through a toll-like receptor 4-nuclear factor-κB-dependent pathway.. Our results support the role for ProT in the development of insulin resistance. Therefore, ProT is a potential novel therapeutic target for type 2 diabetes.

Topics: Aged; Animals; Diabetes Mellitus, Type 2; Diet, High-Fat; Gene Silencing; Genetic Vectors; Glucose; Humans; Insulin Resistance; Lentivirus; Liver; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Middle Aged; Muscle Fibers, Skeletal; NF-kappa B; Protein Precursors; RNA, Small Interfering; Thymosin; Toll-Like Receptor 4

Peripheral neuropathy is one of the most common complications of diabetes mellitus. Using a mouse model of diabetic peripheral neuropathy, we tested the hypothesis that thymosin β4 (Tβ4) ameliorates diabetes-induced neurovascular dysfunction in the sciatic nerve and promotes recovery of neurological function from diabetic peripheral neuropathy. Tβ4 treatment of diabetic mice increased functional vascular density and regional blood flow in the sciatic nerve, and improved nerve function. Tβ4 upregulated angiopoietin-1 (Ang1) expression, but suppressed Ang2 expression in endothelial and Schwann cells in the diabetic sciatic nerve. In vitro, incubation of Human Umbilical Vein Endothelial Cells (HUVECs) with Tβ4 under high glucose condition completely abolished high glucose-downregulated Ang1 expression and high glucose-reduced capillary-like tube formation. Moreover, incubation of HUVECs under high glucose with conditioned medium collected from Human Schwann Cells (HSCs) treated with Tβ4 significantly reversed high glucose-decreased capillary-like tube formation. PI3K/Akt signaling pathway is involved in Tβ4-regulated Ang1 expression on endothelial and Schwann cells. These data indicate that Tβ4 likely acts on endothelial cells and Schwann cells to preserve and/or restore vascular function in the sciatic nerve which facilitates improvement of peripheral nerve function under diabetic neuropathy. Thus, Tβ4 has potential for the treatment of diabetic peripheral neuropathy.

Topics: Animals; Blotting, Western; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Diabetic Neuropathies; Disease Models, Animal; Electrophysiology; Endothelial Cells; Humans; Immunohistochemistry; Laser-Doppler Flowmetry; Mice; Neuroprotective Agents; Real-Time Polymerase Chain Reaction; Regional Blood Flow; Reverse Transcriptase Polymerase Chain Reaction; Schwann Cells; Sciatic Nerve; Signal Transduction; Thymosin