Vitamin D Alleviates Type 2 Diabetes Mellitus by Mitigating Oxidative Stress-Induced Pancreatic ß-Cell Impairment.

OBJECTIVE: Type 2 diabetes mellitus (T2DM) is a common metabolic disorder with rising incidence worldwide. This study explored the anti-T2DM role of vitamin D, thereby providing novel therapeutic strategies. METHODS: C57BL/6 J mice and MIN6 cells were used to induce in vivo T2DM and damaged ß-cell models, respectively. Body weights, fasting blood glucose, and fasting insulin were measured in mice. Oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were conducted on mice. Lipid indices (TG, TC, LDL-C, and HDL-C) were detected in mouse serum. Hematoxylin-eosin staining was used to evaluate pancreatic tissue injury. ELISA was used to assess insulin and oxidative stress (OS) markers (MDA, GSH, and SOD) in mice and MIN6 cells. Production of ROS was detected in islet ß-cells and MIN6 cells. Cell viability and apoptosis were evaluated using CCK-8 and flow cytometry, respectively. QRT-PCR and western blotting were used to detect pro-inflammatory factors (TNF-α and IL-6) and endoplasmic reticulum stress (ERS) markers (CHOP and GRP78), respectively. RESULTS: Vitamin D reduced body weights, fasting blood glucose, and insulin and ameliorated glucose tolerance and insulin sensitivity in T2DM mice. Besides, vitamin D decreased serum TG, TC, LDL-C, and increased HDL-C in T2DM mice. Vitamin D inhibited pancreatic histopathological injury, cell apoptosis, OS, and ß-cell decline in T2DM mice. Moreover, vitamin D alleviated cell death, insufficient insulin secretion, inflammation, OS, and ERS in damaged MIN6 cells. Notably, N-acetyl-L-cysteine (an OS inhibitor) enhanced these effects of vitamin D. CONCLUSIONS: Vitamin D relieved T2DM symptoms by alleviating OS-induced ß-cell impairment.

The metabolome and bacterial composition of high-moisture Italian ryegrass silage inoculated with lactic acid bacteria during ensiling.

BACKGROUND: With its high nutritional value and productivity, Italian ryegrass as a biomass feedstock constantly supplies rumen degradable nitrogen and digestible fiber to ruminants. However, biofuel production is easily reduced during ensiling due to the high-moisture content of Italian ryegrass, leading to economic losses. Lactic acid bacteria inoculants could improve lignocellulosic degradation and fermentation quality and decrease dry matter loss during the bioprocessing of silage. Therefore, this study analyzed the effects of Lactobacillus buchneri TSy1-3 (HE), Lactobacillus rhamnosus BDy3-10 (HO), and the combination of HE and HO (M) on fermentation quality, bacterial community and metabolome in high-moisture Italian ryegrass silage during ensiling. RESULTS: The results showed that the pH value was significantly lower in the HO groups than in the other treatments at the end of ensiling, and the dry matter and acetic acid contents were significantly higher in the HO group than in the other inoculated groups. All inoculants decreased the diversity of the bacterial community and significantly increased the relative abundance of Lactobacillus. Inoculation with HO significantly improved the concentrations of organic acids, dipeptides, ferulic acid, apigenin, and laricitrin. Compared with Lactobacillus buchneri TSy1-3 (HE), HO significantly upregulated the flavonoid compounds in the flavone and flavonol biosynthesis pathway. CONCLUSIONS: Overall, these findings suggest that inoculation with HO was beneficial for the development of Italian ryegrass as a biomass feedstock, improving fermentation quality, accelerating changes in bacterial community composition and increasing biofunctional metabolites in high-moisture Italian ryegrass silage.

Characterization of mycotoxins and microbial community in whole-plant corn ensiled in different silo types during aerobic exposure.

Silage can be contaminated with mycotoxins and accidental fungi after aerobic exposure. The study assessed the effects of bunker silos (BS), round bales (RB), and silage bags (SB) on the nutritional characteristics, fermentation quality, aerobic stability, mycotoxin levels and microbial communities of whole-plant corn silage (WPCS). After 90 days of fermentation, silages were opened and sampled at 0, 1, 3, 5, 7, and 9 days of exposure. SB group conserved higher lactic acid and dry matter contents and a lower pH value than other groups after 9 days of exposure (p < 0.05). The SB group showed the longest aerobic stability (202 h) among all silages (p < 0.05). The concentrations of aflatoxin B1, trichothecenes and fumonisin B1 were significantly lower in SB after 9 days of exposure (p < 0.05). Acetobacter became the dominant bacteria in BS and RB groups after 5 days of exposure. However, Lactobacillus still dominated the bacterial community in SB group. Acetobacter was positively correlated with pH, acetic acid content, and ammonia-N content (p < 0.05). Lactobacillus was positively correlated with Kazachstania and Candida abundances (p < 0.01) but negatively correlated with Fusarium abundance (p < 0.05). Considering the feed value and food safety of silage in the feeding process, silage bags are recommended for WPCS according to the observed nutritional quality, fermentation index and mycotoxin content.

ROS­mediated autophagy through the AMPK signaling pathway protects INS­1 cells from human islet amyloid polypeptide­induced cytotoxicity.

Oligomerization of human islet amyloid polypeptide (hIAPP) is toxic and contributes to progressive reduction of ß cell mass in patients with type 2 diabetes mellitus. Autophagy is a highly conserved homeostatic mechanism in eukaryotes. Previous studies have confirmed that hIAPP can promote autophagy in ß cells, but the underlying molecular mechanism and cellular regulatory pathway of hIAPP­induced autophagy remains not fully elucidated. Accumulation of reactive oxygen species (ROS) causes hIAPP induced­ß cell death. At present, little is known about the association between hIAPP­induced oxidative stress and autophagy in ß cells. Therefore, the present study investigated the underlying molecular mechanism and regulatory pathway of hIAPP­induced autophagy. Transmission electron microscopy was used to observe the number of autophagosome in cells. Cell viability was determined by an MTT test. A 2',7'­dichlorofluorescin diacetate assay was used to measure the relative levels of reactive ROS. Western blotting was used to detect expression of adenosine monophosphate­activated protein kinase (AMPK) and autophagic markers p62 and microtubule associated protein 1 light chain 3. The results demonstrated that hIAPP induces autophagy through ROS­mediated AMPK signaling pathway in INS­1 cells. Upregulation of autophagy by AMPK activator 5­aminoimidazole­4­carboxamide1­ß­D­ribofuranoside decreased ROS and malondialdehyde generation, whereas inhibition of autophagy by 3­methyladenine and AMPK inhibitor compound C aggravated hIAPP­induced oxidative stress and toxicity in INS­1 cells. Taken together, the present study suggested that hIAPP induces autophagy via a ROS­mediated AMPK signaling pathway. Furthermore, autophagy serves as a cell­protective mechanism against hIAPP­induced toxicity and chemical promotion of autophagy through AMPK signaling pathway attenuates hIAPP induced cytotoxicity and oxidative stress in INS­1 cells.

Palmitate induces VSMC apoptosis via toll like receptor (TLR)4/ROS/p53 pathway.

BACKGROUND AND AIMS: Toll-like receptor 4 (TLR4) has been implicated in vascular inflammation, as well as in the pathogenesis of atherosclerosis and diabetes. Vascular smooth muscle cell (VSMC) apoptosis has been shown to induce plaque vulnerability in atherosclerosis. Previous studies reported that palmitate induced apoptosis in VSMCs; however, the role of TLR4 in palmitate-induced apoptosis in VSMCs has not yet been defined. In this study, we investigated whether or not palmitate-induced apoptosis depended on the activation of the TLR4 pathway. METHODS: VSMCs were treated with or without palmitate, CRISPR/Cas9z-mediated genome editing methods were used to deplete TLR4 expression, while NADPH oxidase inhibitors were used to inhibit reactive oxygen species (ROS) generation. Cell apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, ROS was measured using the 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) method, the mRNA and protein expression levels of caspase 3, caspase 9, BCL-2 and p53 were studied by real-time polymerase chain reaction (RT-PCR) and ELISA. RESULTS: Palmitate significantly promotes VSMC apoptosis, ROS generation, and expression of caspase 3, caspase 9 and p53; while NADPH oxidase inhibitor pretreatment markedly attenuated these effects. Moreover, knockdown of TLR4 significantly blocked palmitate-induced ROS generation and VSMC apoptosis accompanied by inhibition of caspase 3, caspase 9, p53 expression and restoration of BCL-2 expression. CONCLUSIONS: Our results suggest that palmitate-induced apoptosis depends on the activation of the TLR4/ROS/p53 signaling pathway, and that TLR4 may be a potential therapeutic target for the prevention and treatment of atherosclerosis.

Reduced serum milk fat globule-epidermal growth factor 8 (MFG-E8) concentrations are associated with an increased risk of microvascular complications in patients with type 2 diabetes.

BACKGROUND: The association between serum milk fat globule-epidermal growth factor 8 (MFG-E8) concentrations and vascular complications in T2DM remains unclear. METHODS: A total of 149 patients with T2DM were included. The serum concentrations of MFG-E8, glycosylated hemoglobin (HbA1c), and high-sensitivity C-reactive protein (hs-CRP) were measured. RESULTS: There was no significant difference in serum MFG-E8 concentrations between the T2DM group and the T2DM with subclinical atherosclerosis (AS) group (615.49±143.54 vs. 596.22±79.46ng/ml, P=0.365), while the serum concentrations of MFG-E8 in the T2DM with microvascular complications group (446.70±61.53ng/ml) and the T2DM with subclinical AS and microvascular complications group (200.87±38.86ng/ml) were significantly lower than those in the T2DM group (P=0.000 for both). In addition, hs-CRP and HbAlc concentrations were independently associated with serum MFG-E8 concentrations (P=0.024 and P=0.01, respectively), and low serum MFG-E8 concentrations were significantly associated with an increased risk of microvascular complications in T2DM patients. CONCLUSIONS: Serum concentrations of MFG-E8 were negatively associated with the risk of microvascular complications in patients with T2DM. Thus, it might be a potential candidate biomarker for diabetic microvascular complications.