High Glucose-induced Inflammation Research Articles

The role of FGF-21 in promoting diabetic wound healing by modulating high glucose-induced inflammation

BackgroundWound healing is a complex biological process that can be impaired in individuals with diabetes. Diabetic wounds are a serious complication of diabetes that require promoting diagnosis and effective treatment. FGF-21, a member of the endocrine FGF factors family, has caught the spotlight in the treatment of diabetes for its beneficial effects on accelerating human glucose uptake and fat catabolism. However, the therapeutic efficacy of FGF-21 in promoting diabetic wounds remains unknown. This study aims to evaluate the therapeutic potential of FGF-21 in promoting diabetic wound healing. Methodswe investigated the effects of FGF-21 on wound healing related-cells under high-glucose conditions using various assays such as CCK8, scratch assay, flow cytometry analysis, endothelial tube-formation assay, and transmission electron microscopy. Furthermore, we used db/db mice to verify the healing-promoting therapeutic effects of FGF-21 on diabetic wounds. We also conducted qRT-PCR, Western blot, and immunofluorescence staining analyses to elucidate the underlying mechanism. ResultOur results indicate that FGF-21 treatment restored hyperglycemic damage on endothelial cell proliferation, migration, and tube-forming ability. It also reduced endothelial cell death rates under high-glucose conditions. TEM analysis showed that FGF-21 treatment effectively restored mitochondrial damage and morphological changes in endothelial cells caused by glucose. Additionally, qRT-PCR and Western blot analysis indicated that FGF-21 treatment restored inflammatory responses caused by hyperglycemic damage. Animal experiments confirmed these findings, suggesting that FGF-21 may be a promising candidate for the treatment of non-healing diabetic wounds due to its effectiveness in stimulating angiogenesis and anti-inflammatory function. ConclusionOur study provides evidence that FGF-21 is an essential regulator of wound-related cells under high-glucose conditions and has the potential to be a novel therapeutic target for accelerating diabetic wound healing.

Endothelial CXCR2 deficiency attenuates renal inflammation and glycocalyx shedding through NF-κB signaling in diabetic kidney disease

BackgroundThe incidence of diabetic kidney disease (DKD) continues to rapidly increase, with limited available treatment options. One of the hallmarks of DKD is persistent inflammation, but the underlying molecular mechanisms of early diabetic kidney injury remain poorly understood. C-X-C chemokine receptor 2 (CXCR2), plays an important role in the progression of inflammation-related vascular diseases and may bridge between glomerular endothelium and persistent inflammation in DKD.MethodsMultiple methods were employed to assess the expression levels of CXCR2 and its ligands, as well as renal inflammatory response and endothelial glycocalyx shedding in patients with DKD. The effects of CXCR2 on glycocalyx shedding, and persistent renal inflammation was examined in a type 2 diabetic mouse model with Cxcr2 knockout specifically in endothelial cells (DKD-Cxcr2eCKO mice), as well as in glomerular endothelial cells (GECs), cultured in high glucose conditions.ResultsCXCR2 was associated with early renal decline in DKD patients, and endothelial-specific knockout of CXCR2 significantly improved renal function in DKD mice, reduced inflammatory cell infiltration, and simultaneously decreased the expression of proinflammatory factors and chemokines in renal tissue. In DKD conditions, glycocalyx shedding was suppressed in endothelial Cxcr2 knockout mice compared to Cxcr2L/L mice. Modulating CXCR2 expression also affected high glucose-induced inflammation and glycocalyx shedding in GECs. Mechanistically, CXCR2 deficiency inhibited the activation of NF-κB signaling, thereby regulating inflammation, restoring the endothelial glycocalyx, and alleviating DKD.ConclusionsTaken together, under DKD conditions, activation of CXCR2 exacerbates inflammation through regulation of the NF-κB pathway, leading to endothelial glycocalyx shedding and deteriorating renal function. Endothelial CXCR2 deficiency has a protective role in inflammation and glycocalyx dysfunction, suggesting its potential as a promising therapeutic target for DKD treatment.

Resveratrol attenuates high glucose-induced inflammation and improves glucose metabolism in HepG2 cells

Diabetes mellitus (DM) is characterized by impaired glucose and insulin metabolism, resulting in chronic hyperglycemia. Hyperglycemia-induced inflammation is linked to the onset and progression of diabetes. Resveratrol (RES), a polyphenol phytoalexin, is studied in diabetes therapeutics research. This study evaluates the effect of RES on inflammation and glucose metabolism in HepG2 cells exposed to high glucose. Inflammation and glucose metabolism-related genes were investigated using qPCR. Further, inflammatory genes were analyzed by applying ELISA and Bioplex assays. High glucose significantly increases IKK-α, IKB-α, and NF-kB expression compared to controls. Increased NF-kB expression was followed by increased expression of pro-inflammatory cytokines, such as TNF-α, IL-6, IL-β, and COX2. RES treatment significantly reduced the expression of NF-kB, IKK-α, and IKB-α, as well as pro-inflammatory cytokines. High glucose levels reduced the expression of TGFβ1, while treatment with RES increased the expression of TGFβ1. As glucose levels increased, PEPCK expression was reduced, and GCK expression was increased in HepG2 cells treated with RES. Further, HepG2 cells cultured with high glucose showed significant increases in KLF7 and HIF1A but decreased SIRT1. Moreover, RES significantly increased SIRT1 expression and reduced KLF7 and HIF1A expression levels. Our results indicated that RES could attenuate high glucose-induced inflammation and enhance glucose metabolism in HepG2 cells.

Autophagy protects peripheral blood mononuclear cells from high glucose-induced inflammation and apoptosis

Previous works have linked high concentrations of glucose to cellular toxicity through autophagy modulation. However, the ways in which high glucose (HG) regulates inflammation and apoptosis in peripheral blood mononuclear cells (PBMCs) have not been well characterized. In the present study, the role of autophagy in inflammatory responses and apoptotic death of PBMCs exposed to HG was investigated. 33mM glucose (HG) increased the level of LC3-II at 12h, 24h, and 48h. NH4Cl, a lysosome inhibitor that can block autophagic flux, further promoted LC3-II accumulation in HGtreated cells at 12h, 24h, and 48h. The protein level of p62 significantly decreased from 12h to 48h in HG-treated cells, suggesting an induction of autophagic flux in HG-treated PBMCs. Inhibiting autophagy with chloroquine (CQ) significantly augmented HGinduced PBMCs apoptotic death, as demonstrated by increased cleaved PARP and Cyt C levels and an increased percentage of apoptotic (YO-PRO-1 positive and PI negative) cells. Furthermore, CQ pretreatment exacerbated HG-induced TNF-α, IL-6, and IL-1β mRNA expression in PBMCs. In conclusion, this data revealed that the autophagy system could be activated in HG-treated PBMCs. The results also indicated that the induction of autophagy might play an adaptive and protective role in HG-induced inflammation and apoptotic death of PBMCs.

Dysregulated CD200-CD200R signaling in early diabetes modulates microglia-mediated retinopathy.

Diabetic retinopathy (DR) is a neurovascular complication of diabetes. Recent investigations have suggested that early degeneration of the neuroretina may occur prior to the appearance of microvascular changes; however, the mechanisms underlying this neurodegeneration have been elusive. Microglia are the predominant resident immune cell in the retina and adopt dynamic roles in disease. Here, we show that ablation of retinal microglia ameliorates visual dysfunction and neurodegeneration in a type I diabetes mouse model. We also provide evidence of enhanced microglial contact and engulfment of amacrine cells, ultrastructural modifications, and transcriptome changes that drive inflammation and phagocytosis. We show that CD200-CD200R signaling between amacrine cells and microglia is dysregulated during early DR and that targeting CD200R can attenuate high glucose-induced inflammation and phagocytosis in cultured microglia. Last, we demonstrate that targeting CD200R in vivo can prevent visual dysfunction, microglia activation, and retinal inflammation in the diabetic mouse. These studies provide a molecular framework for the pivotal role that microglia play in early DR pathogenesis and identify a potential immunotherapeutic target for treating DR in patients.

San Huang Xiao Yan recipe modulates the HMGB1-mediated abnormal inflammatory microenvironment and ameliorates diabetic foot by activating the AMPK/Nrf2 signalling pathway

BackgroundDiabetic foot (DF) is one of the serious complications of diabetes and lacks of therapeutic drugs. Abnormal and chronic inflammation promoting foot infection and wound healing delay are the main pathogenesis of DF. The traditional prescription San Huang Xiao Yan Recipe (SHXY) has been used in the clinical treatment of DF for several decades as approved hospital experience prescription and showed remarkable therapeutic effect, but the mechanisms by which SHXY treats DF are still unclear. PurposeObjectives of this study were to investigate SHXY anti-inflammatory effect on DF and explore the molecular mechanism for SHXY. MethodsWe detected the effects of SHXY on DF in C57 mouse and SD rat DF models. Animal blood glucose, weight and wound area were detected every week. Serum inflammatory factors were detected by ELISA. H&E and Masson's trichrome were used to observe tissue pathology. Single-cell sequencing data reanalysis revealed the role of M1 macrophages in DF. Venn analysis showed the co-target genes between DF M1 macrophages and compound-disease network pharmacology. Western blotting was used to explored target protein expression. Meanwhile, RAW264.7 cells were treated with drug-containing serum of SHXY to further unravel the roles of target proteins during high glucose-induced inflammation in vitro. The Nrf2 inhibitor ML385 was used on RAW 264.7 cells to further explore the relationship between Nrf2, AMPK and HMGB1. The main components of SHXY were analysed by HPLC. Finally, the treatment effect of SHXY on DF were detected on rat DF model. ResultsIn vivo, SHXY can ameliorate inflammatory, accelerate wound healing and upregulate expression of Nrf2, AMPK and downregulate of HMGB1. Bioinformatic analysis showed that M1 macrophages were the main inflammatory cell population in DF. Moreover, the Nrf2 downstream proteins HO-1 and HMGB1 were potential DF therapeutic targets for SHXY. In vitro, we also found that SHXY increased AMPK and Nrf2 protein levels and downregulated HMGB1 expression in RAW264.7 cells. Inhibiting the expression of Nrf2 impaired the inhibition effect of SHXY on HMGB1. SHXY promoted Nrf2 translocation into the nucleus and increased the phosphorylation of Nrf2. SHXY also inhibited HMGB1 extracelluar release under high glucose. In rat DF models, SHXY also exhibited significant anti-inflammatory effect. ConclusionThe SHXY activated AMPK/Nrf2 pathway to suppress abnormal inflammation on DF via inhibiting HMGB1 expression. These findings provide novel insight into the mechanisms by which SHXY treats DF.

Platycodin D inhibits HFD/STZ-induced diabetic nephropathy via inflammatory and apoptotic signaling pathways in C57BL/6 mice

Ethnopharmacological relevanceThe dried root of Platycodon grandiflorum (Jacq.) A.DC. (PG) is a traditional herb used in Asian countries and is widely used in formulas for the treatment of diabetes. Platycodin D (PD) is one of the most important components of PG. Aim of the studyThis study aimed to investigate the improvement effects and regulatory mechanisms of PD on kidney injury in a high-fat diet (HFD) combined with streptozotocin (STZ)-induced diabetic nephropathy (DN). Materials and methodsModel mice were treated with oral gavage of the PD (2.5, 5 mg/kg) for 8 weeks. Determination of serum lipid and renal function-related indexes creatinine (CRE), and blood urea nitrogen (BUN) levels in mice, and histopathological section analysis of kidney. Molecular docking and molecular dynamics were utilized to study the binding ability of PD to target NF-κB and apoptosis signaling pathway-related proteins. Moreover, Western blot was used to test the expressions of NF-κB and apoptosis-related proteins. Vitro experiments were performed to validate the related mechanisms using RAW264.7 cells and HK2 cells cultured by high glucose. ResultsIn vivo experiments, the administration of PD (2.5 and 5.0 mg/kg) reduced fasting blood glucose (FBG) and homeostasis model assessment of insulin resistance (HOMA-IR) levels in DN mice, while lipid levels and renal function were significantly improved. Furthermore, PD significantly inhibited the development of DN in the model mice by regulating NF-κB and apoptotic signaling pathways, reduced the abnormal elevation of serum inflammatory factors TNF-α and IL-1β, and repaired renal cell apoptosis. In vitro experiments, NF-κB inhibitor ammonium pyrrolidine dithiocarbamate (PDTC) was used to confirm that PD can alleviate high glucose-induced inflammation in RAW264.7 cells and inhibit the release of inflammatory factors. And in HK2 cell experiments, it was verified that PD can inhibit ROS generation, reduce the loss of JC-1 and suppress HK2 cell injury by regulating NF-κB and apoptotic pathways. ConclusionsThese data suggested that PD has the potential to prevent and treat DN and is a promising natural nephroprotective agent.

Never in mitosis gene A-related kinase-6 deficiency deteriorates diabetic cardiomyopathy via regulating heat shock protein 72.

NIMA (never in mitosis, gene A)-related kinase-6 (NEK6), a cell cycle regulatory gene, was found to regulate cardiac hypertrophy. However, its role in diabetes-induced cardiomyopathy has not been fully elucidated. This research was designed to illustrate the effect of NEK6 involved in diabetic cardiomyopathy. Here we used a streptozotocin (STZ)-induced mice diabetic cardiomyopathy model and NEK6 knockout mice to explore the role and mechanism of NEK6 in diabetic-induced cardiomyopathy. NEK6 knockout mice and wild-type littermates were subjected to STZ injection (50mg/kg/day for 5days) to induce a diabetic cardiomyopathy model. As a result, 4months after final STZ injection, DCM mice revealed cardiac hypertrophy, fibrosis, and systolic and diastolic dysfunction. NEK6 deficiency causes deteriorated cardiac hypertrophy, fibrosis, and cardiac dysfunction. Furthermore, we observed inflammation and oxidative stress in the hearts of NEK6 deficiency mice under diabetic cardiomyopathy pathology. Adenovirus was used to upregulate NEK6 in neonatal rat cardiomyocytes, and it was found that NEK6 ameliorated high glucose-induced inflammation and oxidative stress. Our findings revealed that NEK6 increased the phosphorylation of heat shock protein 72 (HSP72) and increased the protein level of PGC-1α and NRF2. Co-IP assay experiment confirmed that NEK6 interacted with HSP72. When HSP72 was silenced, the anti-inflammation and anti-oxidative stress effects of NEK6 were blurred. In summary, NEK6 may protect diabetic-induced cardiomyopathy by interacting with HSP72 and promoting the HSP72/PGC-1α/NRF2 signaling. KEY MESSAGES: NEK6 knockout deteriorated cardiac dysfunction, cardiac hypertrophy, fibrosis as well as inflammation response, and oxidative stress. NEK6 overexpression attenuated high glucose induced inflammation and oxidative stress. The underlying mechanisms of the protective role of NEK6 in the development of diabetic cardiomyopathy seem to involve the regulation of HSP72-NRF2- PGC-1α pathway. NEK6 may become a new therapeutic target for diabetic cardiomyopathy.

Macrophage inflammatory protein-1β as a novel therapeutic target for renal protection in diabetic kidney disease

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease worldwide and the prevalence of DKD has increased over recent decades. Inflammation is involved in the development and progression of DKD. In this study, we explored the potential role of macrophage inflammatory protein-1β (MIP-1β) in DKD. Clinical non-diabetic subjects and DKD patients with different levels of urine albumin-to-creatinine ratio (ACR) were enrolled in the study. Leprdb/db mice and MIP-1β knockout mice were also used as mouse models for DKD. We found that serum MIP-1β levels were elevated in the DKD patients, especially those with ACRs that were less than or equal to 300, suggesting that MIP-1β is activated in clinical DKD. The administration of anti-MIP-1β antibodies attenuated DKD severity in the Leprdb/db mice, which also showed reduced glomerular hypertrophy and podocyte injury, as well as decreased inflammation and fibrosis, suggesting that MIP-1β plays a role in the development of DKD. The MIP-1β knockout mice showed improved renal function and decreased renal glomerulosclerosis and fibrosis in DKD. Furthermore, podocytes from the MIP-1β knockout mice showed less high glucose-induced inflammation and fibrosis compared to those from wild-type mice. In conclusion, the inhibition or deletion of MIP-1β protected podocytes, modulated renal inflammation, and ameliorated experimental DKD, suggesting that novel anti-MIP-1β strategies could potentially be used to treat DKD.

Sodium butyrate inhibits high glucose-induced inflammation by controlling the acetylation of NF-κB p65 in human monocytes.

Hyperglycemia is a major cause of diabetes and diabetes-related diseases. Sodium butyrate (NaB) is a short-chain fatty acid derivative that produces dietary fiber by anaerobic bacterial fermentation in the large intestine and occurs in foods, such as Parmesan cheese and butter. Butyrate has been shown to prevent obesity, improve insulin sensitivity, and ameliorate dyslipidemia in diet-induced obese mice. Therefore, this study examined the effects and mechanism of NaB on the secretion of inflammatory cytokines induced by high glucose (HG) in THP-1 cells. THP-1 cells were used as an in vitro model for HG-induced inflammation. The cells were cultured under normal glycemic or hyperglycemic conditions with or without NaB (0-25 μM). Western blotting and quantitative polymerase chain reaction were used to evaluate the protein and mRNA levels of nuclear factor-κB (NF-κB), interleukin-6, tumor necrosis factor-α, acetylated p65, acetyl CREB-binding protein/p300 (CBP/p300), and p300 using THP-1 cells. Histone acetyltransferase (HAT), histone deacetylase (HDAC), and pro-inflammatory cytokine secretion activity were analyzed using an enzyme-linked immunosorbent assay. HG significantly upregulated histone acetylation, acetylation levels of p300, NF-κB activation, and inflammatory cytokine release in THP-1 cells. Conversely, the NaB treatment reduced cytokine release and NF-κB activation in HG-treated cells. It also significantly reduced p65 acetylation, CBP/p300 HAT activity, and CBP/p300 gene expression. In addition, NaB decreased the interaction of p300 in acetylated NF-κB and TNF-α. These results suggest that NaB suppresses HG-induced inflammatory cytokine production through HAT/HDAC regulation in monocytes. NaB has the potential for preventing and treating diabetes and its related complications.

Peroxiredoxin 6 alleviates high glucose-induced inflammation and apoptosis in HK-2 cells by inhibiting TLR4/NF-κB signaling.

This research sought to elucidate the effects of peroxiredoxin 6 (PRDX6) on the biological processes in diabetic nephropathy (DN) and to identify the underlying regulatory mechanism related to toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling. To induce an in vitro DN cellular model, human kidney 2 (HK-2) cells were treated with high glucose (HG). The mitochondrial membrane potential, adenosine triphosphate level, reactive oxygen species generation, and oxidative stress of the cells were then evaluated. After the PRDX6 level had been determined, the effects of its overexpression on the mitochondrial membrane potential, adenosine triphosphate level, reactive oxygen species generation, and oxidative stress of the cells were assessed. Next, cytochrome c expression, cell viability, cell apoptosis, the inflammatory level, and the TLR4/NF-κB signaling-related factors were assessed. After the addition of the TLR4 activator CRX-527 or the NF-κB activator phorbol 12-myristate 13-acetate (PMA), cell viability, cell apoptosis and the inflammatory level were evaluated again. The results revealed that HG exposure triggered mitochondrial dysfunction and oxidative stress and decreased PRDX6 expression in the HK-2 cells. PRDX6 elevation exacerbated cell viability while alleviating mitochondrial membrane potential loss, oxidative stress, apoptosis, and inflammation in the HG-treated HK-2 cells. Further, PRDX6 inhibited HG-induced TLR4/NF-κB activation. The administration of CRX-527 or PMA reversed the effects of PRDX6 on the cell viability, apoptosis, and inflammation of the HG-exposed HK-2 cells. To conclude, PRDX6 appears to protect HG-exposed HK-2 cells against inflammation and apoptosis by inhibiting TLR4/NF-κB signaling.

Maslinic Acid Suppresses High Glucose-induced Inflammation by Epigenetically Inhibiting TXNIP Expression.

Hyperglycemia-induced inflammation and subsequent endothelial injuries ultimately lead to the pathogenesis of cardiovascular diseases associated with high mortality, such as atherosclerosis. Maslinic acid (MA) is a phytochemical with anti-inflammatory activity. However, it remains unknown whether it can inhibit diabetes-associated cardiovascular inflammation. The present study aimed to determine the effect of MA on high glucose-induced endothelial inflammation and apoptosis in human umbilical vein endothelial cells (HUVECs) and to explore the underlying mechanism. HUVECs were treated with high glucose to induce inflammation and apoptosis. Apoptosis was determined by flow cytometry. CCK-8 assay was used to examine cell viability. Production levels of cytokines were detected by quantitative realtime PCR (qPCR) and ELISA. Protein expression levels and signaling pathways activation were detected by Western blotting. RNA immunoprecipitation and qPCR were used to determine the N6-methyladenosine (m6A) levels of target mRNAs. MA promoted the recruitment of RNA demethylase ALKBH5 to TXNIP mRNA, and subsequently enhanced its m6A demethylation. By this means, MA decreased the stability of TXNIP mRNA and downregulated its expression level. Subsequently, reactive oxygen species (ROS) and production of pro-inflammatory cytokines, including TNF-α, IL-6 and IL-1β, were inhibited. And high glucose-induced apoptosis in HUVECs was inhibited by MA. MA ameliorates high glucose-induced endothelial inflammation and injury, serving as a new potential therapeutic application for protecting against diabetes-associated atherosclerosis and other inflammatory diseases.

Suppression of lncRNA Snhg1 inhibits high glucose-induced inflammation and proliferation in mouse mesangial cells

Diabetic nephropathy (DN) is the direct cause of end-stage renal disease, and nephritic inflammation plays a role in its growth and advancement. Aberrant expression of long non-coding RNAs (lncRNAs) correlates with many diseases, including DN. In this study, we investigated whether lncRNA small nucleolar RNA host gene 1 (Snhg1) was mechanistically involved in inflammation and mesangial cell (MC) proliferation in DN. We found that Snhg1 was significantly upregulated in DN renal tissues and high glucose (HG)-treated MCs. Overexpression of Snhg1 promoted inflammatory cytokine expression in MCs and MC proliferation under low-glucose conditions; meanwhile, Snhg1 knockdown suppressed inflammatory cytokine production and MC proliferation under HG conditions. Mechanistically, Snhg1 was found to directly bind miR-27b, thereby preventing the miRNA from binding its target KDM6B mRNA. Furthermore, miR-27b overexpression recapitulated the inhibitory effects of Snhg1 knockdown, whereas restoration of Snhg1 expression attenuated the function of miR-27b in MCs under HG conditions. Taken together, these results indicate that suppression of Snhg1 inhibited HG-induced inflammation and proliferation of MCs by regulating the miR-27b/KDM6B axis.

Knockdown of ILK Alleviates High Glucose-Induced Damage of H9C2 Cells through TLR4/MyD88/NF-κB Pathway.

The aim of this study was to explore the role of ILK in an in vitro model of diabetic cardiomyopathy. We used 30 mmol/L high glucose to treat H9C2 cells to construct an in vitro model, knocked down the ILK expression level of H9C2 cells by small interference technology, and detected the activity of antioxidant enzymes and inflammatory factors in the supernatant. The expression levels of SOD1 and IL-1β were detected by immunofluorescence staining. The expression levels of the TLR4/MyD88/NF-κB signaling pathway and its downstream factors were detected by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Compared with the control group, after high-glucose culture of H9C2 cells, the cell activity decreased, while the apoptosis rate increased, with the TLR4/MyD88/NF-κB signaling pathway activated, thereby inducing oxidative stress and inflammation. Compared with the high-glucose group, the HG+si-ILK group increased cell activity, decreased the apoptosis rate, and inhibited the excessive activation of the TLR4/MyD88/NF-κB signaling pathway, thereby improving oxidative stress and inflammation. Knockdown of ILK expression can protect H9C2 cells from reducing high glucose-induced inflammation, oxidative stress, and apoptosis by inhibiting the TLR4/MyD88/NF-κB signaling pathway.

MG53 represses high glucose-induced inflammation and angiogenesis in human retinal endothelial cells by repressing the EGR1/STAT3 axis

Background Diabetic retinopathy (DR) is a vascular complication of diabetes mellitus that leads to visual injury and blindness. Both angiogenesis and inflammation play an important role in the pathogenesis of DR. Here we aimed to explore the mechanisms of mitsugumin 53 (MG53) in ameliorating the dysfunction induced by high glucose (HG) in humans retinal microvascular endothelial cells (HRECs). Methods HRECs were subjected to HG in the presence or absence of MG53 overexpression. The effect of MG53 on cell viability and inflammatory response in HG-treated HRECs was measured using the Cell Counting Kit-8 and ELISAs, respectively. Expression of MG53, EGR1, p-STAT3, FGF2, TGFB1, and Angiopoietin-1 in HG-treated HRECs was quantified by western blot or quantitative real-time polymerase chain reaction. Results HG significantly downregulated MG53 in HRECs, which reduced cell viability while inducing angiogenesis and inflammatory response. Upregulation of MG53 reversed these effects of HG. MG53 directly interacted with EGR1 and repressed its expression, which decreased phosphorylation of STAT3 and downregulated FGF2, TGFB1, and Angiopoietin-1. EGR1 up-regulation or STAT3 activation antagonized the protective effects of MG53. Conclusion MG53 alleviates HG-induced dysfunction in HRECs by repressing EGR1/STAT3 signaling. Thereby MG53 may have therapeutic potential in DR.

Gambogenic acid protects against high glucose-induced damage of renal tubular epithelial cells by inhibiting pyroptosis through regulating the AMPK–TXNIP pathway

Diabetic nephropathy, a chronic inflammatory disease, is characterized by hyperglycemia-stimulated pyroptosis of renal tubular epithelial cells. Gambogic acid, a primary component of gamboge resin, exerts detoxification, antioxidant, anticancer, anti-angiogenesis and anti-inflammatory capacities. However, the nephroprotective effect of gambogic acid on diabetic nephropathy remains unknown. Human kidney (renal) epithelial cell line HK-2 was treated with dextrorotatory-glucose (D-glucose) to establish an in vitro cell model of diabetic nephropathy, followed by incubation with gambogic acid. CCK-8 was designed to detect cell viability. Enzyme-linked-immunosorbent serologic assay (ELISA) was used to detect the levels of inflammation-related factors. Pyroptosis and underlying mechanism were investigated by Western blot assay. High glucose treatment decreased the viability of HK-2 cell line, while gambogic acid incubation restored the reduced cell viability. High glucose-induced increase in the levels of tumor necrosis factor-α (TNF-α), Interleukin (IL)-6, Monocyte chemoattractant protein-1 (MCP-1) and IL-1β were reduced by gambogic acid. The protein expressions of NLR family pyrin domain containing 3 (NLRP3), N-terminal domain of gasdermin D (GSDMD-N), caspase-1, IL-1β and IL-18 were up-regulated in HK-2 cells after high glucose condition, while down-regulated by incubation of gambogic acid. Gambogic acid attenuated high glucose-induced increase of thioredoxin-interacting protein (TXNIP) and phosphorylated 5' adenosine monophosphate-activated protein kinase (p-AMPK) in HK-2 cell line. Gambogenic acid protected renal tubular epithelial cells against high glucose-induced inflammation and pyroptosis through suppression of AMPK–TXNIP pathway, providing a potential strategy for the prevention of diabetic nephropathy.

Baicalein suppresses high glucose-induced inflammation and apoptosis in trophoblasts by targeting the miRNA-17-5p-Mfn1/2-NF-κB pathway

Controlling inflammation and apoptosis in trophoblasts is critical for treating gestational diabetes mellitus (GDM). Baicalein (Bai) exhibits anti-inflammatory and miRNA-related effects; however, its roles and mechanisms in GDM remain unknown. Therefore, we explored whether Bai inhibited inflammation and apoptosis in human trophoblasts (HTR8 cells) and analyzed its mechanisms. HTR8 cells pretreated with Bai were subjected to the high-glucose (HG) stimulation before analyzing their viability, cytokine production and apoptosis, followed the expression profiles of small RNA sequencing data. The effects of miR-17-5p on the inflammation, mitochondrial fission, and apoptosis were investigated by ELISA, transmission electron microscopy and flow cytometry, respectively. Moreover, miR-17-5p, Mfn1/Mfn2 levels and mitochondrial morphology in human plasma and placental tissues from GDM-complicated and normal pregnant women were examined. Bai decreased the secretion of TNF-α, IL-1β, IL-6 and apoptosis in HG-stimulated HTR8 cells, while miR-17-5p mediated the anti-inflammatory and anti-apoptotic effects of Bai. Mechanically, miR-17-5p targeted Mfn1/Mfn2 by affecting the mitochondrial fission and apoptosis via regulation of p-Drp1 (Ser 616) and p-NF-κB signaling. Moreover, overexpression of Mfn1/Mfn2 reversed miR-17-5p-elicited mitochondrial fission and inflammation in HG-stimulated HTR8 cells pretreated with Bai. Furhtermore, overexpression of Drp1 also reversed the anti-inflammatory effect of Mfn1/2 overexpression in HG-treated HTR8 cells via up-regulation of p65 phosphorylation. Finally, miR-17-5p was upregulated in human GDM plasma and placentas along with the reduced Mfn1/Mfn2. We are the first to demonstrate that bai exerts anti-inflammatory and anti-apoptotic effects on GDM, likely by targeting the miRNA-17-5p-Mfn1/2-NF-κB pathway.

Loss of Function of WFS1 Causes ER Stress-Mediated Inflammation in Pancreatic Beta-Cells.

Wolfram syndrome is a rare genetic disorder characterized by juvenile-onset diabetes mellitus, optic nerve atrophy, hearing loss, diabetes insipidus, and progressive neurodegeneration. Pathogenic variants in the WFS1 gene are the main causes of Wolfram syndrome. WFS1 encodes a transmembrane protein localized to the endoplasmic reticulum (ER) and regulates the unfolded protein response (UPR). Loss of function of WFS1 leads to dysregulation of insulin production and secretion, ER calcium depletion, and cytosolic calpains activation, resulting in activation of apoptotic cascades. Although the terminal UPR has been shown to induce inflammation that accelerates pancreatic β-cell dysfunction and death in diabetes, the contribution of pancreatic β-cell inflammation to the development of diabetes in Wolfram syndrome has not been fully understood. Here we show that WFS1-deficiency enhances the gene expression of pro-inflammatory cytokines and chemokines, leading to cytokine-induced ER-stress and cell death in pancreatic β-cells. PERK and IRE1α pathways mediate high glucose-induced inflammation in a β-cell model of Wolfram syndrome. M1-macrophage infiltration and hypervascularization are seen in the pancreatic islets of Wfs1 whole-body knockout mice, demonstrating that WFS1 regulates anti-inflammatory responses in pancreatic β-cells. Our results indicate that inflammation plays an essential role in the progression of β-cell death and diabetes in Wolfram syndrome. The pathways involved in ER stress-mediated inflammation provide potential therapeutic targets for the treatment of Wolfram syndrome.

Knockdown of GPRC5B alleviates the high glucose-induced inflammation and extracellular matrix deposition of podocyte through inhibiting NF-κB pathway.

Diabetes is a serious disease that could greatly increase the risk of cardiovascular complications, whereas the underlying pathology of DN is still unknown. GPRC5B is a member of the RAIG subfamily of type 3 (family C) GPCR, and its role in DN is still unclear. To unveil the role of GPRC5B in diabetic nephropathy (DN) progression and investigate the potential signaling pathway. Podocytes were stimulated with high glucose and expression of GPRC5B was analyzed by qPCR and western blot. Then the level of GPRC5B was depleted by siRNA transfection and inflammatory cytokine level was monitored by ELISA assay. The ECM depostion and the activation of NF-κB pathway were detected by Immunoblot. We investigated the possible role of GPRC5B in the pathology of diabetic nephropathy. We found GPRC5B was highly expressed in high glocuse (HG) induced podocytes. The depletion of GPRC5B inhibited HG induced cell inflammation. In addition, the ablation of GPRC5B suppressed the HG induced ECM deposition. We further found GPRC5B could alleviate the inflammation and extracellular matrix deposition of HG-induced podocytes through NF-κB pathway. We therefore thought GPRC5B could serve as a promising target for the treatment of diabetic nephropathy. G-protein-coupled receptors.

Vitamin D protects against high glucose-induced pancreatic β-cell dysfunction via AMPK-NLRP3 inflammasome pathway

Vitamin D deficiency is considered a pandemic and has been postulated to increase the risk of type 2 diabetes mellitus (T2DM). Activation of nod-like receptor protein 3 (NLRP3) signaling induced by hyperglycemia stress has been recognized as a key priming stage for pancreatic β-cell inflammation in T2DM pathogenesis. AMP-activated protein kinase (AMPK) activation attenuates NLRP3 inflammasome upregulation in diabetes. This study investigated whether vitamin D3 could protect cells against high glucose-induced inflammation by modulating this critical step. A human cross-sectional study of 78 healthy, glucose-tolerant volunteers and 399 patients with type 2 diabetes was undertaken. The relationship between serum 25(OH)D3 levels and β-cell function was assessed using Pearson correlation analysis and multiple linear regression, and a high-glucose diet-induced rat model of impaired glucose tolerance was used to evaluate the effects of cholecalciferol. Intraperitoneal glucose tolerance tests and an ELISA were performed to detect the function of pancreatic islets. Glucose-stimulated insulin secretion, pyroptosis, reactive oxygen species (ROS) production, and NLRP3 pathway were evaluated together to determine the role of vitamin D in high glucose-induced pancreatic β-cell dysfunction in INS-1E cells. The clinical results showed a positive association between serum 25(OH)D3 levels and β-cell function in male patients with type 2 diabetes. In vivo, cholecalciferol significantly reduced blood glucose levels and improved insulin secretion in response to glucose loading in the high glucose diet-induced rat model. In vitro studies have demonstrated that 1,25(OH)2D3 promotes insulin release in both islets and INS-1E cells. Mechanistically, our results demonstrated that vitamin D3 can activate AMPK, inhibiting the mTOR pathway, thus inhibiting NLRP3 inflammasome activation and alleviating pyroptosis in β-cell dysfunction. This study showed that vitamin D protects against high-glucose-induced β-cell dysfunction by enhancing the AMPK pathway, thereby suppressing NLRP3 inflammasome activation.