Mitochondria-associated membranes contribution to exercise-mediated alleviation of hepatic insulin resistance: Contrasting high-intensity interval training with moderate-intensity continuous training in a high-fat diet mouse model.

OBJECTIVE: Mitochondria-associated membranes (MAMs) serve pivotal functions in hepatic insulin resistance (IR). Our aim was to explore the potential role of MAMs in mitigating hepatic IR through exercise and to compare the effects of different intensities of exercise on hepatic MAMs formation in high-fat diet (HFD) mice. METHODS: Male C57BL/6J mice were fed an HFD and randomly assigned to undergo supervised high-intensity interval training (HIIT) or moderate-intensity continuous training (MICT). IR was evaluated using the serum triglyceride/high-density lipoprotein cholesterol ratio (TG/HDL-C), glucose tolerance test (GTT), and insulin tolerance test (ITT). Hepatic steatosis was observed using hematoxylin-eosin (H&E) and oil red O staining. The phosphatidylinositol 3-kinase/protein kinase B/glycogen synthase kinase 3 beta (PI3K-AKT-GSK3ß) signaling pathway was assessed to determine hepatic IR. MAMs were evaluated through immunofluorescence (colocalization of voltage-dependent anion-selective channel 1 [VDAC1] and inositol 1,4,5-triphosphate receptor [IP3R]). RESULTS: After 8 weeks on an HFD, there was notable inhibition of the hepatic PI3K/Akt/GSK3ß signaling pathway, accompanied by a marked reduction in hepatic IP3R-VDAC1 colocalization levels. Both 8-week HIIT and MICT significantly enhanced the hepatic PI3K/Akt/GSK3ß signaling and colocalization levels of IP3R-VDAC1 in HFD mice, with MICT exhibiting a stronger effect on hepatic MAMs formation. Furthermore, the colocalization of hepatic IP3R-VDAC1 positively correlated with the expression levels of phosphorylation of protein kinase B (p-AKT) and phosphorylation of glycogen synthase kinase 3 beta (p-GSK3ß), while displaying a negative correlation with serum triglyceride/high-density lipoprotein cholesterol levels. CONCLUSION: The reduction in hepatic MAMs formation induced by HFD correlates with the development of hepatic IR. Both HIIT and MICT effectively bolster hepatic MAMs formation in HFD mice, with MICT demonstrating superior efficacy. Thus, MAMs might wield a pivotal role in exercise-induced alleviation of hepatic IR.

Synthetic poly(vinyl alcohol)-chitosan as a new type of highly efficient hemostatic sponge with blood-triggered swelling and high biocompatibility.

Rapid and effective hemostasis for a noncompressible hemorrhage is the key to control bleeding and reduce mortality. Chitosan (CS) has been widely used as a popular hemostatic dressing; however, irregularly shaped wounds present in emergencies limit the performance of CS powder. To improve the hemostatic effect of CS, we modified it with poly(vinyl alcohol) (PVA), a fast-swelling sponge triggered by water. The novel synthetic PVA-CS was prepared by cross-linking PVA and CS during foaming and crosslinking reactions. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction were utilized to analyze the characteristics of PVA-CS. In vitro, the swelling ratio and blood clotting ability were evaluated in different groups with various weight ratios or degrees of deacetylation of the CS, and the cytocompatibility and cell attachment on the material were analyzed by human dermal fibroblast (HDF) cell testing. In vivo, the hemostatic effects were evaluated in Sprague-Dawley rats and Bama miniature pigs in a femoral artery hemorrhage model or gunshot wound experiment. PVA-CS presents robust mechanical strength, rapid water-triggered swelling and a fast absorption speed. As compared with gauze and PVA, which are widely used in first aid, PVA-CS sponges showed an improved blood clotting ability and increased blood cell and platelet adhesion and activation. The PVA-CS sponges also showed high biocompatibility in cell viability, cell proliferation and cell attachment bioassays. Furthermore, in vivo evaluation of the PVA-CS sponges revealed excellent hemostatic performance and enhanced wound healing with increased re-epithelialization and decreased granulation tissues. The results of this study strongly support the use of these composite sponges for noncompressible hemorrhage in acute trauma and ballistic injuries.

Hydroxychloroquine protects melanocytes from autoantibody-induced injury by reducing the binding of antigen-antibody complexes.

Vitiligo is a polygenic autoimmune disorder characterized by loss of pigmentation due to melanocyte destruction. Hydroxychloroquine (HCQ) is an effective immunosuppressant widely used in the treatment of autoimmune disorders. As generalized vitiligo (GV) is commonly considered to be a T cell and autoantibody-induced immune disorder, the present study aimed to determine whether HCQ protects melanocytes from autoantibody­induced disruption. Anti­melanocyte antibodies were obtained from the serum of patients with progressive GV and the effects of HCQ on prevent the autoantibody­induced disruption of melanocytes was observed. Cell­based ELISA, indirect immunofluorescence and western blotting were used to analyze the autoantibody content of sera samples obtained from 32 patients with progressive GV. The cytotoxicity of HCQ was detected by MTT assay, and 1 µg/ml HCQ was applied to human primary melanocytes (HMCs) to examine whether it could exert protective effects against autoantibody­induced immune injury. Flow cytometry was used to measure autoantibody binding to the surface of HMCs. Complement­dependent cytotoxicity (CDC) and antibody­dependent cell­mediated cytotoxicity (ADCC) were monitored by MTT and lactate dehydrogenase­releasing assays. The concentration of autoantibodies in sera samples taken from GV patients was significantly higher than in controls, particularly in patients who had >10% of their body surface affected by vitiligo. The majority of the autoantibodies presented in the HMCs and human keratinocytes (HKCs) and were predominantly localized to the cell surface and cytoplasm. The molecular weights of the autoantigens were identified as 30, 37­39, 42, 53, 60­75, 90, 100, 110, and 126 kDa; the 30 kDa protein was observed only in HMCs. The addition of HCQ at a concentration of 1 µg/ml produced no significant cytotoxicity in HMCs and was demonstrated to reduce the binding of GV immunoglobulin G (IgG) to the surface of HMCs. HCQ also significantly decreased the effects of ADCC and CDC that were mediated by GV IgG. The present study provides evidence that HCQ dissociates autoantibody-antigen complexes on the surface of HMCs and reverses ADCC and CDC activity in vitro. Thus, in addition to its effectiveness as an antimalarial therapeutic agent, HCQ may also be a promising potential treatment for patients with vitiligo.