Targeting ferroptosis: New perspectives of Chinese herbal medicine in the treatment of diabetes and its complications.

Ferroptosis is a non-apoptotic mode of cell death. A large number of studies have confirmed that ferroptosis plays a vital role in the occurrence and development of diabetes and diabetic complications. Previous studies have found that Chinese herbal medicines have very promising results in the prevention and treatment of diabetes and diabetic complications, and some of these herbs or herbal natural compounds may act via the inhibition of ferroptosis. In this review, we summarized the relationship between ferroptosis and diabetes and diabetic complications, and discussed its molecular mechanisms. We also reviewed the published studies of herbal medicines or herbal natural compounds that improved diabetes or diabetic complications via the ferroptosis pathway. In addition, we are trying to provide new insights for better treatment of diabetes and diabetic complications with Chinese herbal medicine and its herbal compounds.

High glucose-induced STING activation inhibits diabetic wound healing through promoting M1 polarization of macrophages.

Diabetic wound (DW) is characterized by elevated pro-inflammatory cytokines and cellular dysfunction consistent with elevated reactive oxygen species (ROS) levels. Recent advances in immunology have dissected molecular pathways involved in the innate immune system where cytoplasmic DNA can trigger STING-dependent inflammatory responses and play an important role in metabolic-related diseases. We investigated whether STING regulates inflammation and cellular dysfunction in DW healing. We found that STING and M1 macrophages were increased in wound tissues from DW in patients and mice and delayed the wound closure. We also noticed that the massively released ROS in the High glucose (HG) environment activated STING signaling by inducing the escape of mtDNA to the cytoplasm, inducing macrophage polarization into a pro-inflammatory phenotype, releasing pro-inflammatory cytokines, and exacerbating endothelial cell dysfunction. In Conclusion, mtDNA-cGAS-STING pathway activation under diabetic metabolic stress is an important mechanism of DW refractory healing. While using STING gene-edited macrophages for wound treatment by cell therapy can induce the polarization of wound macrophages from pro-inflammatory M1 to anti-inflammatory M2, promote angiogenesis, and collagen deposition to accelerate DW healing. STING may be a promising therapeutic target for DW.

Yishen Huashi granule modulated lipid metabolism in diabetic nephropathy via PI3K/AKT/mTOR signaling pathways.

Aim: Diabetic nephropathy (DN) is the primary cause of end-stage renal disease worldwide. Although etiology for DN is complex and still needs to be fully understood, lipid metabolism disorder is found to play a role in it. Previously, we found Yishen Huashi (YSHS) granule could inhibit diabetic damage and reduce level of microalbuminuria (mALB) in DN animals. To explore its role and mechanism in lipid metabolism under DN settings, this study was designed. Materials and methods: DN rats were induced by streptozotocin (STZ), HepG2 and CaCO2 cells were applied for in vitro study. Hematoxylin-Eosin (HE), periodic acid-Schiff (PAS) staining, and Transmission Electron Microscopy (TEM) were applied for histological observation; 16s Sequencing was used for intestinal microbiota composition analysis; western blotting (WB) and immunofluorescence were carried out for molecular biological study, and enzyme-linked immunosorbent assay (ELISA) was used for lipid determination. Results: YSHS administration significantly reduced levels of total cholesterol (TC), triglyceride (TG), and low-density lipoprotein (LDL-C), while increased level of high-density lipoprotein (HDL-C); meanwhile, histological changes and steatosis of the liver was ameliorated, integrity of the intestinal barrier was enhanced, and dysbacteriosis within intestinal lumen was ameliorated. Mechanism study found that YSHS modulated mitophagy within hepatocytes and inhibited mTOR/AMPK/PI3K/AKT signaling pathway. Conclusion: In conclusion, we found in the present study that YSHS administration could ameliorate lipid metabolism disorder in DN animals, and its modulation on intestinal-liver axis played a significant role in it.

High Glucose-Induced Kidney Injury via Activation of Necroptosis in Diabetic Kidney Disease.

Diabetic kidney disease (DKD) is a major microvascular complication of diabetes mellitus (DM) and is closely associated to programmed cell death. However, the complex mechanisms of necroptosis, an alternative cell death pathway, in DKD pathogenesis are yet to be elucidated. This study indicates that necroptosis is involved in DKD induced by high glucose (HG) both in vivo and in vitro. HG intervention led to the activation of RIPK1/RIPK3/MLKL signaling, resulting in renal tissue necroptosis and proinflammatory activation in streptozotocin/high-fat diet- (STZ/HFD-) induced diabetic mice and HG-induced normal rat kidney tubular cells (NRK-52E). We further found that in HG-induced NRK-52E cell, necroptosis might, at least partly, depend on the levels of reactive oxygen species (ROS). Meanwhile, ROS participated in necroptosis via a positive feedback loop involving the RIPK1/RIPK3 pathway. In addition, blocking RIPK1/RIPK3/MLKL signaling by necrostatin-1 (Nec-1), a key inhibitor of RIPK1 in the necroptosis pathway, or antioxidant N-acetylcysteine (NAC), an inhibitor of ROS generation, could effectively protect the kidney against HG-induced damage, decrease the release of proinflammatory cytokines, and rescue renal function in STZ/HFD-induced diabetic mice. Inhibition of RIPK1 effectively decreased the activation of RIPK1-kinase-/NF-κB-dependent inflammation. Collectively, we demonstrated that high glucose induced DKD via renal tubular epithelium necroptosis, and Nec-1 or NAC treatment downregulated the RIPK1/RIPK3/MLKL pathway and finally reduced necroptosis, oxidative stress, and inflammation. Thus, RIPK1 may be a therapeutic target for DKD.

WDR74 facilitates TGF-ß/Smad pathway activation to promote M2 macrophage polarization and diabetic foot ulcer wound healing in mice.

Diabetic foot ulcer (DFU) is a devastating component of diabetes progression, leading to decreased quality of life and increased mortality in diabetic patients. The underlying mechanism of DFU is not completely understood. Hence, this study aims to elucidate the mechanism involved in wound healing in mouse models of DFU. Gain- and loss-of-function studies were performed to study the roles that WDR74 and TGF-ß play in mouse models of DFU and primary bone marrow-derived mouse macrophages. M1 and M2 macrophage phenotypic markers, extracellular matrix (ECM) components, and angiogenic makers were determined by RT-qPCR and/or Western blot analysis. Localization of these proteins was determined by immunofluorescence staining and/or immunohistochemistry. Interaction between WDR74 with Smad2/3 in macrophages was detected by co-immunoprecipitation. We found that WDR74 and M2 macrophages were decreased in wound tissues from DFU mice. TGF-ß/Smad pathway activation increased the expression of M2 macrophage markers (arginase-1 and YM1), IL-4, while decreased expression of M1 macrophage marker (iNOS). TGF-ß/Smad pathway activation also increased the production of ECM and promoted the wound closure in diabetic mice. We also noticed that WDR74 overexpression increased Smad2/3 phosphorylation, elevated the population of M2 macrophage and ECM production, and alleviated DFU. LY2109761 treatment normalized effects of TGF-ß or WDR74 overexpression. In conclusion, WDR74 promoted M2 macrophage polarization, leading to improved DFU in mice, through activation of the TGF-ß/Smad pathway. Graphical Headlights 1. WDR74 promotes M2 macrophage polarization and ECM production. 2. WDR74 activates the TGF-ß/Smad signaling pathway. 3. TGF-ß/Smad activation promotes M2 macrophage polarization in murine DFU. 4. WDR74 enhances wound healing in murine DFU.

Targeting Pyroptosis: New Insights into the Treatment of Diabetic Microvascular Complications.

Pyroptosis is an inflammatory form of programmed cell death that is dependent on inflammatory caspases, leading to the cleavage of gasdermin D (GSDMD) and increased secretion of interleukin (IL)-1ß and IL-18. Recent studies have reported that hyperglycemia-induced cellular stress stimulates pyroptosis, and different signaling pathways have been shown to play crucial roles in regulating pyroptosis. This review summarized and discussed the molecular mechanisms, regulation, and cellular effects of pyroptosis in diabetic microvascular complications, such as diabetic nephropathy, diabetic retinopathy, and diabetic cardiomyopathy. In addition, this review aimed to provide new insights into identifying better treatments for diabetic microvascular complications.

Intake of flavonoids from Astragalus membranaceus ameliorated brain impairment in diabetic mice via modulating brain-gut axis.

BACKGROUND: Brain impairment is one of a major complication of diabetes. Dietary flavonoids have been recommended to prevent brain damage. Astragalus membranaceus is a herbal medicine commonly used to relieve the complications of diabetes. Flavonoids is one of the major ingredients of Astragalus membranaceus, but its function and mechanism on diabetic encepholopathy is still unknown. METHODS: Type 2 diabetes mellitus (T2DM) model was induced by high fat diet and STZ in C57BL/6J mice, and BEnd.3 and HT22 cell lines were applied in the in vitro study. Quality of flavonoids was evaluated by LC-MS/MS. Differential expressed proteins in the hippocampus were evaluated by proteomics; influence of the flavonoids on composition of gut microbiota was analyzed by metagenomics. Mechanism of the flavonoids on diabetic encepholopathy was analyzed by Q-PCR, Western Blot, and multi-immunological methods et al. RESULTS: We found that flavonoids from Astragalus membranaceus (TFA) significantly ameliorated brain damage by modulating gut-microbiota-brain axis: TFA oral administration decreased fasting blood glucose and food intake, repaired blood brain barrier, protected hippocampus synaptic function; improved hippocampus mitochondrial biosynthesis and energy metabolism; and enriched the intestinal microbiome in high fat diet/STZ-induced diabetic mice. In the in vitro study, we found TFA increased viability of HT22 cells and preserved gut barrier integrity in CaCO2 monocellular layer, and PGC1α/AMPK pathway participated in this process. CONCLUSION: Our findings demonstrated that flavonoids from Astragalus membranaceus ameliorated brain impairment, and its modulation on gut-brain axis plays a pivotal role. Our present study provided an alternative solution on preventing and treating diabetic cognition impairment.

Chronic Ethanol Consumption Induces Osteopenia via Activation of Osteoblast Necroptosis.

Chronic high-dose alcohol consumption impairs bone remodeling, reduces bone mass, and increases the risk of osteoporosis and bone fracture. However, the mechanisms underlying alcohol-induced osteoporosis are yet to be elucidated. In this study, we showed that excess intake of ethyl alcohol (EtOH) resulted in osteopenia and osteoblast necroptosis in mice that led to necrotic lesions and reduced osteogenic differentiation in bone marrow mesenchymal stem cells (BMMSCs). We found that EtOH treatment led to the activation of the RIPK1/RIPK3/MLKL signaling, resulting in increased osteoblast necroptosis and decreased osteogenic differentiation and bone formation both in vivo and in vitro. We further discovered that excessive EtOH treatment-induced osteoblast necroptosis might partly depend on reactive oxygen species (ROS) generation; concomitantly, ROS contributed to necroptosis of osteoblasts through a positive feedback loop involving RIPK1/RIPK3. In addition, blocking of the RIPK1/RIPK3/MLKL signaling by necrostatin-1 (Nec-1), a key inhibitor of RIPK1 kinase in the necroptosis pathway, or antioxidant N-acetylcysteine (NAC), an inhibitor of ROS, could decrease the activation of osteoblast necroptosis and ameliorate alcohol-induced osteopenia both in vivo and in vitro. Collectively, we demonstrated that chronic high-dose alcohol consumption induced osteopenia via osteoblast necroptosis and revealed that RIPK1 kinase may be a therapeutic target for alcohol-induced osteopenia.

Kuwanon G protects HT22 cells from advanced glycation end product-induced damage.

The incidence of diabetic encephalopathy is increasing as the population ages. Evidence suggests that formation and accumulation of advanced glycation end products (AGEs) plays a pivotal role in disease progression, but limited research has been carried out in this area. A previous study demonstrated that Kuwanon G (KWG) had significant anti-oxidative stress and anti-inflammatory properties. As AGEs are oxidative products and inflammation is involved in their generation it is hypothesized that KWG may have effects against AGE-induced neuronal damage. In the present study, mouse hippocampal neuronal cell line HT22 was used. KWG was shown to significantly inhibit AGE-induced cell apoptosis in comparison with a control treatment, as determined by both MTT and flow cytometry. Compared with the AGEs group, expression of pro-apoptotic protein Bax was reduced and expression of anti-apoptotic protein Bcl-2 was increased in the AGEs + KWG group. Both intracellular and extracellular levels of acetylcholine and choline acetyltransferase were significantly elevated after KWG administration in comparison with controls whilethe level of acetylcholinesterase decreased. These changes in protein expression were accompanied by increased levels of superoxide dismutase and glutathione peroxidase synthesis and reduced production of malondialdehyde and reactive oxygen species. Intracellular signaling pathway protein levels were determined by western blot and immunocytochemistry. KWG administration was found to prevent AGE-induced changes to the phosphorylation levels of Akt, IκB-α, glycogen synthase kinase 3 (GSK3)-α and ß, p38 MAPK and NF-κB p65 suggesting a potential neuroprotective effect of KWG against AGE-induced damage was via the PI3K/Akt/GSK3αß signaling pathway. The findings of the present study suggest that KWG may be a potential treatment for diabetic encephalopathy.

Non-Digestible Carbohydrate and the Risk of Colorectal Neoplasia: A Systematic Review.

Non-digestible carbohydrate (NDC) is a fiber that can be fermented into short chain fatty acids (SCFAs) in gut, represented by resistant starch (RS) and inulin. Colorectal cancer (CRC) is one of the most common malignant cancer. Pre-clinical studies have reported that NDC can produce SCFAs to protect the gut epithelium, which is associated with prevention of CRC, but this role in clinical trails is controversial. In this review, we discusses whether RS and inulin should be offered to cancer/precancerous patients or healthy subjects to decrease their risk of CRC. A multiple database search was conducted for studies published on RS/inulin supplementation as a chemopreventive method from 1989 to 2019. The meta-analysis showed the total SCFAs and butyrate concentrations (P = 0.84; P = 0.79), and excretions (P = 0.55; P = 0.63) in feces did not increase significantly after RS/inulin supplementation. Only two studies reported that RS/inulin inhibit the proliferation of large bowel epithelial, whereas 15 studies showed that it does not decrease the risk of neoplasia. RS/inulin restored the promotion of tumor risk factors in two studies and did not in four studies. Notably, the other four studies showed that RS increases pro-tumorigenesis mechanisms. The clinical evidences consistently show that RS/inulin is ineffective for preventing colorectal neoplasia.

Short-Chain Fatty Acids Ameliorate Diabetic Nephropathy via GPR43-Mediated Inhibition of Oxidative Stress and NF-κB Signaling.

Diabetic nephropathy (DN) is a chronic low-grade inflammatory disease. Oxidative stress and nuclear factor kappa B (NF-κB) signaling play an important role in the pathogenesis of DN. Short-chain fatty acids (SCFAs) produced from carbohydrate fermentation in the gastrointestinal tract exert positive regulatory effects on inflammation and kidney injuries. However, it is unclear whether SCFAs can prevent and ameliorate DN. In the present study, we evaluated the role and mechanism of the three main SCFAs (acetate, propionate, and butyrate) in high-fat diet (HFD) and streptozotocin- (STZ-) induced type2 diabetes (T2D) and DN mouse models and in high glucose-induced mouse glomerular mesangial cells (GMCs), to explore novel therapeutic strategies and molecular targets for DN. We found that exogenous SCFAs, especially butyrate, improved hyperglycemia and insulin resistance; prevented the formation of proteinuria and an increase in serum creatinine, urea nitrogen, and cystatin C; inhibited mesangial matrix accumulation and renal fibrosis; and blocked NF-κB activation in mice. SCFAs also inhibited high glucose-induced oxidative stress and NF-κB activation and enhanced the interaction between ß-arrestin-2 and I-κBα in GMCs. Specifically, the beneficial effects of SCFAs were significantly facilitated by the overexpression GPR43 or imitated by a GPR43 agonist but were inhibited by siRNA-GPR43 in GMCs. These results support the conclusion that SCFAs, especially butyrate, partially improve T2D-induced kidney injury via GPR43-mediated inhibition of oxidative stress and NF-κB signaling, suggesting SCFAs may be potential therapeutic agents in the prevention and treatment of DN.

Sodium Butyrate-Modulated Mitochondrial Function in High-Insulin Induced HepG2 Cell Dysfunction.

The liver plays a pivotal role in maintaining euglycemia. Biogenesis and function of mitochondria within hepatocytes are often the first to be damaged in a diabetic population, and restoring its function is recently believed to be a promising strategy on inhibiting the progression of diabetes. Previously, we demonstrated that the gut microbiota metabolite butyrate could reduce hyperglycemia and modulate the metabolism of glycogen in both db/db mice and HepG2 cells. To further explore the mechanism of butyrate in controlling energy metabolism, we investigated its influence and underlying mechanism on the biogenesis and function of mitochondria within high insulin-induced hepatocytes in this study. We found that butyrate significantly modulated the expression of 54 genes participating in mitochondrial energy metabolism by a PCR array kit, both the content of mitochondrial DNA and production of ATP were enhanced, expressions of histone deacetylases 3 and 4 were inhibited, beta-oxidation of fatty acids was increased, and oxidative stress damage was ameliorated at the same time. A mechanism study showed that expression of GPR43 and its downstream protein beta-arrestin2 was increased on butyrate administration and that activation of Akt was inhibited, while the AMPK-PGC-1alpha signaling pathway and expression of p-GSK3 were enhanced. In conclusion, we found in the present study that butyrate could significantly promote biogenesis and function of mitochondria under high insulin circumstances, and the GPR43-ß-arrestin2-AMPK-PGC1-alpha signaling pathway contributed to these effects. Our present findings will bring new insight on the pivotal role of metabolites from microbiota on maintaining euglycemia in diabetic population.

The efficacy and safety of combinations of SGLT2 inhibitors and GLP-1 receptor agonists in the treatment of type 2 diabetes or obese adults: a systematic review and meta-analysis.

PURPOSE: To evaluate the efficacy and safety of combination therapy with sodium-glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists in the treatment of type 2 diabetes mellitus (T2DM) or obese adults. METHODS: A meta-analysis was conducted of trials by searching in PubMed, Embase, CENTRAL, Web of Science, and Scopus. RESULTS: A total of five randomized controlled trials (RCTs) and six nonrandomized controlled trials (NCTs) enrolled 1604 participants were identified for meta-analysis. Compared with control/placebo, the combination therapy group had significantly reduced fasting plasma glucose level and 2 h postprandial glucose by 1.28 mmol/L (95% confidence interval [CI]: -1.39, -1.16; p < 0.001) and 1.34 mmol/L (95% CI: -1.47, -1.21; p < 0.001); glycosylated hemoglobin (HbA1c) by 1.32% (95% CI: -1.43, -1.20; p < 0.001); body weight by 0.93 kg (95% CI: -1.04, -0.83; p < 0.001), and systolic blood pressure (SBP) by 1.05 mmHg (95% CI: -1.17, -0.93; p < 0.001). The incidence of genital mycotic infections and urinary infections did not significantly differ from those in the control group, with relative risks (RRs) of 1.67 (95% CI: 0.85, 3.27; p = 0.651) and 1.25 (95% CI: 0.73, 2.15; p = 0.905), respectively. A decreased incidence of cardiovascular events was seen in the combination therapy group (RR = 0.19; 95% CI: 0.04, 0.96; p = 0.403), while an incidence of hypoglycemia was reported (RR = 2.22; 95% CI: 1.20, 4.10; p = 0.71). CONCLUSIONS: SGLT2 inhibitors and GLP-1 agonists combination treatment improved glycemic control, reduced body weight, and decreased SBP without an increase in total adverse events or genital and urinary infections in patients with T2DM or obesity.

Sodium butyrate alleviates high-glucose-induced renal glomerular endothelial cells damage via inhibiting pyroptosis.

We recently found that Sodium butyrate (NaB) possesses anti-inflammatory effects in diabetic nephropathy (DN) mouse model and in high-glucose induced mouse glomerular mesangial cells. Pyroptosis is a programmed cell death accompanied with the release of pro-inflammatory factors. Gasdermin D (GSDMD) is a novel discovered pivotal executive protein of pyroptosis, which can be cleaved by inflammatory caspases. The aim of our study is to verify if NaB have some effects against high-glucose induces pyroptosis in renal Glomerular endothelial cells (GECs). For this aim, human GECs were cultured and exposed to high-glucose. Exogenous NaB, caspase 1 inhibitor Ac-YVAD-CMK (A-Y-C) or knockdown GSDMD by siRNA were used. We found high glucose could increase Propidium Iodide (PI) positive cells and elevate release of lactate dehydrogenase (LDH), Interleukin 1 beta (IL-1ß) and Interleukin 18 (IL-18); protein levels of GSDMD, GSDMD N-terminal domain (GSDMD-N) and cleaved-caspase-1 were also elevated. Effect of NaB on LDH release and PI positive cells was further enhanced by inhibiting caspase 1-GSDMD. In addition, high glucose-induced nuclear factor kappa-B (NF-κB)/NF-κB inhibitor α (IκB-α) signaling pathway was reversed by NaB or A-Y-C administration. In conclusion, NaB could ameliorate high-glucose induced GECs via caspase1-GSDMD canonical pyroptosis pathway; and NF-κB/IκB-α signaling pathway was involved in it.

Sodium Butyrate Improves Liver Glycogen Metabolism in Type 2 Diabetes Mellitus.

Liver plays a central role in modulating blood glucose level. Our most recent findings suggested that supplementation with microbiota metabolite sodium butyrate (NaB) could ameliorate progression of type 2 diabetes mellitus (T2DM) and decrease blood HbA1c in db/db mice. To further investigate the role of butyrate in homeostasis of blood glucose and glycogen metabolism, we carried out the present study. In db/db mice, we found significant hypertrophy and steatosis in hepatic lobules accompanied by reduced glycogen storage, and expression of GPR43 was significantly decreased by 59.38 ± 3.33%; NaB administration significantly increased NaB receptor G-protein coupled receptor 43 (GPR43) level and increased glycogen storage in both mice and HepG2 cells. Glucose transporter 2 (GLUT2) and sodium-glucose cotransporter 1 (SGLT1) on cell membrane were upregulated by NaB. The activation of intracellular signaling Protein kinase B (PKB), also known as AKT, was inhibited while glycogen synthase kinase 3 (GSK3) was activated by NaB in both in vivo and in vitro studies. The present study demonstrated that microbiota metabolite NaB possessed beneficial effects on preserving blood glucose homeostasis by promoting glycogen metabolism in liver cells, and the GPR43-AKT-GSK3 signaling pathway should contribute to this effect.

High Glucose and Lipopolysaccharide Prime NLRP3 Inflammasome via ROS/TXNIP Pathway in Mesangial Cells.

While inflammation is considered a central component in the development in diabetic nephropathy, the mechanism remains unclear. The NLRP3 inflammasome acts as both a sensor and a regulator of the inflammatory response. The NLRP3 inflammasome responds to exogenous and endogenous danger signals, resulting in cleavage of procaspase-1 and activation of cytokines IL-1ß, IL-18, and IL-33, ultimately triggering an inflammatory cascade reaction. This study observed the expression of NLRP3 inflammasome signaling stimulated by high glucose, lipopolysaccharide, and reactive oxygen species (ROS) inhibitor N-acetyl-L-cysteine in glomerular mesangial cells, aiming to elucidate the mechanism by which the NLRP3 inflammasome signaling pathway may contribute to diabetic nephropathy. We found that the expression of thioredoxin-interacting protein (TXNIP), NLRP3, and IL-1ß was observed by immunohistochemistry in vivo. Simultaneously, the mRNA and protein levels of TXNIP, NLRP3, procaspase-1, and IL-1ß were significantly induced by high glucose concentration and lipopolysaccharide in a dose-dependent and time-dependent manner in vitro. This induction by both high glucose and lipopolysaccharide was significantly inhibited by N-acetyl-L-cysteine. Our results firstly reveal that high glucose and lipopolysaccharide activate ROS/TXNIP/ NLRP3/IL-1ß inflammasome signaling in glomerular mesangial cells, suggesting a mechanism by which inflammation may contribute to the development of diabetic nephropathy.

[Review on the development of sol-gel coated open tubular capillary column].

The methods of preparing sol-gel open tubular capillary column are introduced. The characteristics and major factors of sol-gel column preparation method are analyzed and its applications in gas chromatography, high performance liquid chromatography, capillary electrophoresis and capillary electroosmotic chromatography are reviewed.