DM Mice Research Articles

Hesperidin activates the GLP-1R/cAMP-CREB/IRS2/PDX1 pathway to promote transdifferentiation of islet α cells into β cells Across the spectrum

Background and aimsIn all age, FoShou as a Chinese medicinal herb has been active in various kinds of Traditional Chinese medicine formula to treating diabetes. Hesperidin (HES), the main monomeric component of FoShou, has been extensively investigated for interventions with pathogenic mechanism of diabetes as well as subsequent treatment of associated complications. Islet β-cells have an essential effect on dynamically regulating blood sugar. Functional abnormalities in these cells and their death are strongly associated with the onset of diabetes. Therefore, induction of islet endocrine cell lineage re-editing for damaged βcell replenishment would be a promising therapeutic tool. Previously, it has been found that HES can protect islet β-cells in vivo, But, the regenerative function of HES in islet β cells and its role in promoting differential non-β cells transdifferentiation into β cells and cell fate rewriting associated mechanisms remain unclear.This work focused on investigating whether HES can induce islet α cells transdifferentiation into β cells for achieving damaged β cell regeneration and the causes and possible mechanisms involved in the process. Materials and methodsIn brief, 60 mg/kg/d streptozotocin (STZ) was administered intraperitoneally in each male C57bL/6J mouse raised by the high-sugar and high-fat diet (HFD) to create a diabetic mouse model with severe β-cell damage. After 28 consecutive days of HES treatment (160 mg/kg; 320 mg/kg; once daily, as appropriate). Tracing the dynamics of α as well as β cell transformation, together with β cells growth and apoptosis levels during treatment by cell lineage tracing. The self-enforcing transcriptional network on which the cell lineage is based is used as a clue to explore the underlying mechanisms. Guangdong Pharmaceutical University's Animal Experiment Ethics Committee (GDPulac2019180) approved all animal experiments. ResultsLocalization by cell lineage we find that transdifferentiated newborn β-cells derived from α cells appeared in the islet endocrine cell mass of DM mice under HES'action. Compared to the model group, expressed by Tunel staining and CXCL10 levels the overall apoptosis rate of β-cells of the pancreas were reduced,the inflammatory infiltration feedback from HE staining were lower.Ki-67 positive cells showed enhanced β-cell proliferation. Decreased HbA1c and blood glucose contents, elevated C-Peptide and insulin contents which respond to ability of nascent beta cells. Also upregulated the mRNA levels of MafA, Ngn3, PDX-1, Pax4 and Arx. Moreover, increased the expression of TGR5/cAMP-CREB/GLP-1 in mouse intestinal tissues and GLP-1/GLP-1R and cAMP-CREB/IRS2/PDX-1 in pancreatic tissues. ConclusionsHES directly affects β-cells, apart from being anti-apoptotic and reducing inflammatory infiltration. HES promotes GLP-1 release by intestinal L cells by activating the TGR5 receptor in DM mouse and regulating its response element CREB signaling. GLP-1 then uses the GLP-1/GLP-1R system to act on IRS2, IRS2 as a port to influence α precursor cells to express PDX-1, with the mobilization of Pax4 strong expression than Arx so that α cell lineage is finally reversed for achieving β cell endogenous proliferation.

Circ-Erbb2ip from adipose-derived mesenchymal stem cell-derived exosomes promotes wound healing in diabetic mice by inducing the miR-670-5p/Nrf1 axis

BackgroundTo investigate the mechanism of exosomes (Exo) secretion by hypoxic pretreated adipose-derived mesenchymal stem cells (ADSCs) promoting skin wound healing in diabetic (DM) mice. MethodsHigh-throughput sequencing was used to investigate abnormal expression of circRNA in hypoxic pretreatment ADSCs exosome (HExo) and ADSCs exosome (Exo). Bioinformatics analysis and luciferase reporting analysis were used to clarify the interacted relationship among circRNA, miRNA and mRNA. EPCs cells were employ to analysis the ROS, inflammatory cytokines expression, angiogenic differentiation function under hypoxic condition by using immunofluorescence, ELISA detection and tube forming experiment. DM ulceration mice model were constructed and the therapeutic effect of Exo were detected using immunohistochemistry, immunofluorescence. ResultsThe result show that HExo have more treatment effect than Exo in promotes cutaneous wound healing of DM mice. High-throughput sequencing found that circ-Erbb2ip play a role in HExo mediated tissues repair. Downregulation circ-Erbb2ip decreased the therapeutic effect of HExo to wound healing in diabetic mice. Bioinformatics analysis and luciferase reporting analysis confirmed that both miR-670-5p and Nrf1 were downstream targets of circ-Erbb2ip. Downregulation of Nrf1 or overexpression of miR-670-5p reversed the protective effect of circ-Erbb2ip to EPCs after exposure to high glucose microenvironment. Upregulation circ-Erbb2ip increased the therapeutic effect of Exo to wound healing in diabetic mice by increased angiogenesis and decreased ROS, inflammatory cytokines expression. ConclusionIn conclusion, ADSC-Exos containing circ-Erbb2ip promotes wound healing by targeting miR-670-5p/Nrf1 pathway, and their effects in promoting soft tissue wound healing warrant further study.

Chemerin regulates glucose and lipid metabolism by changing mitochondrial structure and function associated with androgen/androgen receptor.

The adipokine chemerin contributes to exercise-induced improvements in glucose and lipid metabolism; however, the underlying mechanism remains unclear. We aimed to confirm the impact of reduced chemerin expression on exercise-induced improvement in glycolipid metabolism in male diabetic (DM) mice through exogenous chemerin administration. Furthermore, the underlying mechanism of chemerin involved in changes in muscle mitochondria function mediated by androgen/androgen receptor (AR) was explored by generating adipose-specific and global chemerin knockout (adipo-chemerin-/- and chemerin-/-) mice. DM mice were categorized into the DM, exercised DM (EDM), and EDM + chemerin supplementation groups. Adipo-chemerin-/- and chemerin-/- mice were classified in the sedentary or exercised groups and fed either a normal or high-fat diet. Exercise mice underwent a 6-wk aerobic exercise regimen. The serum testosterone and chemerin levels, glycolipid metabolism indices, mitochondrial function, and protein levels involved in mitochondrial biogenesis and dynamics were measured. Notably, exogenous chemerin reversed exercise-induced improvements in glycolipid metabolism, AR protein levels, mitochondrial biogenesis, and mitochondrial fusion in DM mice. Moreover, adipose-specific chemerin knockout improved glycolipid metabolism, enhanced exercise-induced increases in testosterone and AR levels in exercised mice, and alleviated the detrimental effects of a high-fat diet on mitochondrial morphology, biogenesis, and dynamics. Finally, similar improvements in glucose metabolism (but not lipid metabolism), mitochondrial function, and mitochondrial dynamics were observed in chemerin-/- mice. In conclusion, decreased chemerin levels affect exercise-induced improvements in glycolipid metabolism in male mice by increasing mitochondrial number and function, likely through changes in androgen/AR signaling.NEW & NOTEWORTHY Decreased chemerin levels affect exercise-induced improvements in glycolipid metabolism in male mice by increasing mitochondrial number and function, which is likely mediated by androgen/androgen receptor expression. This study is the first to report the regulatory mechanism of chemerin in muscle mitochondria.

Targeting the histone methyltransferase SETD7 rescues diabetes-induced impairment of angiogenic response by transcriptional repression of semaphorin 3G

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Swiss National Science Foundation (n. 310030_197557), the Swiss Heart Foundation (n. FF19045) Background Peripheral artery disease (PAD) is highly prevalent in patients with diabetes (DM) and associates with a poor prognosis (1). Revascularization strategies failed to improve outcome, highlighting the need to develop new strategies to promote blood vessel growth (2). Histone modifications have emerged as key modulators of gene expression (3), however their role in angiogenic response in DM remains poorly understood. The present study investigates the role of chromatin remodelling in DM-related impairment of angiogenic response. Methodology Primary human aortic endothelial cells (HAECs) were exposed to normal glucose (NG, 5 mM) or high glucose (HG, 25 mM) levels for 48 hours. Unbiased gene expression profiling was performed by RNA sequencing (RNA-seq). Cell migration and tube formation were employed to study angiogenic properties in HAECs. Levels of the histone methyltransferase SETD7 and its chromatin signature at histone 3 on lysine 4 (H3K4me1) were investigated by Western blot and chromatin immunoprecipitation (ChIP). Pharmacological blockade of SETD7 was achieved by using the selective inhibitor (R)-PFI-2 while the inactive enantiomer (S)-PFI-2 was used as a control. Mice with streptozotocin-induced DM were orally treated with (R)-PFI-2 or vehicle and underwent hindlimb ischemia by femoral artery ligation. Blood flow was analysed at 24 hours, 7 and 14 days by laser Doppler imaging. Our experimental findings were also translated in endothelial cells (ECs) and gastrocnemius muscle samples obtained from DM patients with PAD. Results RNA-seq in HG-treated HAECs unveiled the histone methyltransferase SETD7 as the top-ranking transcript. SETD7 upregulation was associated with increased H3K4me1 levels as well as with impaired HAECs migration and tube formation. Both SETD7 silencing and inhibition by (R)PFI-2 rescued hyperglycemia-induced impairment of HAECs migration and tube formation, while SETD7 overexpression blunted the angiogenic response. RNA-seq and ChIP assays showed that SETD7-induced H3K4me1 enables the transcription of the angiogenesis inhibitor semaphorin-3G (SEMA-3G) by increasing chromatin accessibility to PPARγ. Moreover, SEMA-3G overexpression mimicked the impairment of angiogenic response observed during hyperglycemia. In DM mice with hindlimb ischemia, (R)-PFI-2 improved limb perfusion by suppressing SEMA-3G. Finally, RNAseq in vascular specimens from DM patients with PAD confirmed the upregulation of SETD7/SEMA3G signalling, whereas SETD inhibition restored angiogenic properties in ECs from DM patients. Conclusion SETD7 is a novel epigenetic target to boost neovascularization in DM patients with PAD.

#993 The molecular effects of SGLT2i (Empagliflozin) on α-Klotho and Nephrin/Podocin proteins in type II diabetic mice model

Abstract Background and Aims Type 2 diabetes mellitus (T2DM), especially hyperglycemia, is associated with increased glucose cell toxicity and oxidative stress that can lead to irreversible damage in the kidney such as diabetic nephropathy (DN). DN is one of the most common microvascular complications of diabetes and is the leading cause of end-stage renal disease (ESRD) and replacement therapy. Several works in the setting of early experimental diabetic nephropathy using the recent anti-diabetic drugs such as sodium-glucose transporter type 2 inhibitors in the prevention, development or amelioration of renal injury. The exact mechanisms, by which these drugs ameliorate glomerular injury from hyperglycemia, had not been clarified well. Klotho and Podocin-Nephrin proteins are an important proteins involved in the tubule-glomerular injury. The Klotho is a circulating anti-ageing hormone with anti-oxidative and anti-inflammatory properties with vascular protective effects in animal studies. Podocin & Nephrin are important component of the glomerular foot-process membrane, the slit-diaphragm. Recently, several experimental reports showed decreased α-Klotho, Nephrin and Podocin expression in different models of diabetic nephropathy. Method We used BTBR mouse strain with the ob/ob leptin-deficiency mutation, which develops T2DM with hyperglycemia and DN; C57/BL mice were the control (CON). EMPA was administrated to T2DM mice (T2DM+EMPA) via drinking water for 12 weeks. Blood parameters were measured repeatedly, and at sacrifice, mice kidneys were harvested for histological and biochemical analyses. We evaluated renal glomerular structure of Nephrin, Podocin and α-Klotho proteins expression. Results EMPA treatment reduced T2DM blood glucose vs C57 group (P < 0:01), and increase urine glucose in EMPA+DM group (P < 0:001) EMPA vs. C57BL/6 and DM). Histological analyses in kidney sections, revealed decreased α-Klotho expression in glomeruli of DM mice vs Control mice (15.95 ± 0.64 vs 36 ± 2.42, (P < 0:01), and restored back in DM+ EMPA mice vs control mice (27.64 ± 0.94 vs 15.95 ± 0.64, P < 0:01). Podocin expression in glomeruli: control mice 31.3 ± 3.7 VS DM mice 21.26 ± 1.22 and DM + EMPA mice 28.22 ± 0.50 VS DM mice 21.26 ± 1.22 Conclusion Hyperglycemia (DM type II) reduces Podocin-Nephrin and α-Klotho proteins expression in the glomeruli kidney and upregulated by EMPA treatment. SGLT2i (EMPA) treatment in DM patients can significantly reduce progression of DN and onset of ESRD probably through its effect on α-Klotho/Podocin-Nephrin proteins.

Perubahan Berat Badan Mencit (Mus musculus) Model Diabetes Melitus Tipe 1 yang Diterapi Ekstrak Alga Coklat Sargassum sp

In type 1 diabetes, when the body does not produce enough insulin or none at all. This causes blood glucose levels to remain high while the body's cells are starved for energy. As a result, the body turns to alternative energy sources, namely fat and muscle, leading to weight loss. Sargassum sp contains steroid, alkaloid, phenol, flavonoid, saponin and tannin compounds that can be antioxidant and antidiabetic. This study aims to determine changes in body weight of mice (Mus musculus) type 1 diabetes mellitus models treated with Sargassum sp. This study is an experimental study. Mice were divided into 6 groups, namely KN, K-, K+, P1, P2 and P3. Body weight was weighed on day 0, day 14 (post STZ induction) and day 28 (post drug administration). The data were analysed by ANOVA using SPSS program. The results showed that Sargassum sp extract can increase the body weight of DM mice.

N-acetylcysteine Protects Against Myocardial Ischemia–Reperfusion Injury Through Anti-ferroptosis in Type 1 Diabetic Mice

The hearts of subjects with diabetes are vulnerable to ischemia–reperfusion injury (IRI). In contrast, experimentally rodent hearts have been shown to be more resistant to IRI at the very early stages of diabetes induction than the heart of the non-diabetic control mice, and the mechanism is largely unclear. Ferroptosis has recently been shown to play an important role in myocardial IRI including that in diabetes, while the specific mechanisms are still unclear. Non-diabetic control (NC) and streptozotocin-induced diabetic (DM) mice were treated with the antioxidant N-acetylcysteine (NAC) in drinking water for 4 week starting at 1 week after diabetes induction. Mice were subjected to myocardial IRI induced by occluding the coronary artery for 30 min followed by 2 h of reperfusion, subsequently at 1, 2, and 5 week of diabetes induction. The post-ischemic myocardial infarct size in the DM mice was smaller than that in NC mice at 1 week of diabetes but greater than that in the NC mice at 2 and 5 week of diabetes, which were associated with a significant increase of ferroptosis at 2 and 5 week but a significant reduction of ferroptosis at 1 week of diabetes. NAC significantly attenuated post-ischemic ferroptosis as well as oxidative stress and reduced infarct size at 2 and 5 week of diabetes. Application of erastin, a ferroptosis inducer, reversed the cardioprotective effects of NAC. It is concluded that increased oxidative stress and ferroptosis are the major factors attributable to the increased vulnerability to myocardial IRI in diabetes and that attenuation of ferroptosis represents a major mechanism whereby NAC confers cardioprotection against myocardial IRI in diabetes.

Synergistic Osteogenic and Antiapoptotic Framework Nucleic Acid Complexes Prevent Diabetic Osteoporosis

AbstractDiabetes mellitus (DM) is characterized by elevated blood glucose and advanced glycation end product (AGEs) levels. Increased AGEs in bone tissue inhibit osteogenic differentiation by bone marrow mesenchymal stem cells (BMSCs), leading to bone loss and osteoporosis in diabetic patients. Enhancing the osteogenic differentiation capacity of BMSCs in the presence of abundant AGEs can improve bone health and prevent osteoporosis in DM patients. The flavonoid, Quercetin, has anti‐inflammatory, antibacterial, and antitumor properties; however, it is insoluble in water and thus not easily absorbed by the body. Nanodrug delivery systems such as tetrahedral framework nucleic acids (tFNAs) exhibit excellent biocompatibility, efficient cell uptake, and drug piggybacking. In the present study, tFNAs with quercetin is complexed to form a novel nanodrug (tFNAs/Que) that combined the features of both components. tFNAs/Que promote osteogenic differentiation by BMSCs in an in vitro AGEs‐rich environment, maintain bone mass, and prevent diabetic osteoporosis in DM mice in vivo. The mechanism of tFNAs/Que against AGEs may be related to the JNK signaling pathway. In conclusion, it is shown that tFNAs/Que has a dual regulatory role by promoting osteogenic differentiation and inhibiting apoptosis. Such a feature is promising for the prevention and treatment of diabetic osteoporosis.

Drp1-dependent mitochondrial fragmentation mediates photoreceptor abnormalities in type 1 diabetic retina

Recent studies have highlighted that retinal neurodegeneration precedes microvascular changes in diabetic retinopathy (DR), but the specific mechanisms remain unclear. Given the pivotal role of dysfunctional mitochondria and oxidative stress in early DR, our objective was to observe mitochondria-related alterations in the neural retina of type one diabetic mellitus mice with no evidence of DR (T1DM-NDR). We aimed to identify the key mitochondrial-related proteins contributing to mitochondrial injury. Our study revealed that T1DM-NDR mice exhibited outer retina thinning, including the ellipsoid zone, inner segment, and outer segment. Additionally, there was an impaired amplitude of the b-wave in electroretinogram (ERG) and a disorganized arrangement of the photoreceptor layer. In both the retina of DM mice and high glucose (HG)-treated 661w cells, mitochondria appeared swollen and fragmented, with disrupted cristae, disorganized or shortened branches in the mitochondrial network, and decreased mitochondrial membrane potential. Among the mitochondrial-related proteins, dynamin-related protein 1 (Drp1) was upregulated, and the ratio of phosphorylated Drp1 protein at serine 616 (S616) and serine 637 (S637) sites significantly increased in the retina of DM mice. The administration of Mdivi-1 ameliorated high-glucose-induced dysfunctional mitochondria, thereby protecting T1DM-NDR mice retina from morphological and functional injuries. Our findings suggest that hyperglycemia promotes Drp1-mediated mitochondrial dysfunction, which may be a significant factor in the development of DR. The inhibition of high-glucose-induced mitochondrial fission emerges as a potential and innovative intervention strategy for preventing DR.

Connexin43 overexpression promoted ferroptosis and increased myocardial vulnerability to ischemia-reperfusion injury in type 1 diabetic mice.

Enhancement of Connexin43 (Cx43) and ferroptosis are respectively associated with the exacerbation of myocardial ischemia-reperfusion injury (MIRI) in diabetes. Myocardial vulnerability to ischemic insult has been shown to vary during early and later phases of diabetes in experimental settings. Whether or not Connexin43 (Cx43) and ferroptosis interplay during MIRI in diabetes is unknown. We, thus, aimed to investigate whether or not the content of myocardial Cx43 may be attributable to myocardial vulnerability to MIRI at different stages of diabetes and also to explore the potential interplay between Cx43 and ferroptosis in this pathology. Age-matched control and subgroups of Streptozotocin-induced diabetic mice were subjected to MIRI induced by 30 minutes coronary artery occlusion and 2 hours reperfusion respectively at 1, 2 and 5 weeks of diabetes. Rat cardiac H9C2 cells were exposed to high glucose (HG) for 48h in the absence or presence of Cx43 gene knockdown followed by hypoxia/reoxygenation (HR) respectively for 6 and 12 hours. Post-ischemic myocardial infarct size was reduced in 1 and 2 weeks DM mice concomitant with enhanced GPX4 and reduced cardiac Cx43 and ferroptosis as compared to control. By contrast, cardiac GPX4 was significantly reduced while Cx43 increased at DM 5 weeks (D5w) which was correspondent to significant increases in ferroptosis and myocardial infarction. Post-ischemic cardiac function was improved in 1 and 2 weeks but worsened in 5w DM mice as compared with non-diabetic control. GAP19 (Cx43 inhibitor) significantly attenuated ferroptosis and reduced myocardial infarction in D5w mice. Erastin (ferroptosis activator) reversed the cardioprotective effect of GAP19. In vitro, HR significantly reduced cell viability accompanied with reduced GPX4 but elevated Cx43 expression, MDA production and ferroptosis. Cx43 gene knockdown in H9C2 resulted in a significant increase in GPX4, reduction in MDA and ferroptosis, and subsequently reduced post-hypoxic cell viability. The beneficial effects of Cx43 gene knock-down was minified or eliminated by Erastin. It is concluded that Cx43 overexpression exacerbates MIRI under diabetic conditions via promoting ferroptosis, while its down-regulation at early state of diabetes is attributable to enhanced myocardial tolerance to MIRI.

Ocular surface changes in mice with streptozotocin-induced diabetes and diabetic polyneuropathy

PurposeDiabetes mellitus (DM) is a leading risk factor for corneal neuropathy and dry eye disease (DED). Another common consequence of DM is diabetic peripheral polyneuropathy (DPN). Both complications affect around 50 % of the DM patients but the relationship between DM, DED and DPN remains unclear. MethodsIn this study, we examined mice with early onset of DM and PN after streptozotocin (STZ)-induced diabetes (DPN). We compared the early morphological changes of the sciatic nerve, dorsal root and trigeminal ganglia with the changes in the ocular surface, including tear proteomic and we also investigated respective changes in the gene expressions and morphological alterations in the eye tissues involved in tear production. ResultsThe lacrimal gland, conjunctival goblet cells and cornea showed morphological changes along with alterations in tear proteins without any obvious signs of ocular surface inflammation. The gene expression for respectively altered tear proteins i.e., of Clusterin in cornea, Car6, Adh3a1, and Eef1a1 in eyelids, and Pigr in the lacrimal gland also showed significant changes compared to control mice. In the trigeminal ganglia like in the dorsal root ganglia neuronal cells showed swollen mitochondria and, in the latter, there was a significant increase of NADPH oxidases and MMP9 suggestive of oxidative and neuronal stress. In the dorsal root ganglia and the sciatic nerve, there was an upregulation of a number of pro-inflammatory cytokines and pain-mediating chemokines. ConclusionThe early ocular changes in DM Mice only affect the lacrimal gland. Which, is reflected in the tear film composition of DPN mice. Due to the high protein concentration in tear fluid in humans, proteomic analysis in addition to noninvasive investigation of goblet cells and cornea can serve as a tools for the early diagnosis of DPN, DED in clinical practice. Early treatment could delay or even prevent the ocular complications of DM such as DED and PN.

Sevoflurane anesthesia reduces the expression of inflammatory response genes and β-site amyloid precursor protein-cleaving enzyme in hippocampi of diabetic mice.

Diabetes and inhaled anesthesia are associated with an increased likelihood of developing postoperative cognitive dysfunction in humans and animal models, but the mechanisms are unclear. This study aimed to investigate the effect and mechanism of sevoflurane anesthesia on cognitive function in diabetic (DM) mice. Spontaneously diabetic db/db and control db/m mice were subject to sevoflurane anesthesia or allowed to breathe air, respectively. The Morris water maze test as spatial learning and novel object recognition test as recognition memory were performed. The expression of inflammatory cytokines and neurotoxicity-related genes in the hippocampus of four groups was measured using real-time PCR. The expression level of neurotoxicity and neuroprotection-related proteins in DM mice hippocampus were estimated using Western blot assay. It is found that DM mice developed cognitive impairment; however, the cognitive impairment was not exacerbated in sevoflurane-exposed mice. Sevoflurane anesthesia led to a decrease in mRNA levels of inflammatory cytokines in DM mice hippocampi, including interleukin 17 (IL-17), C-C motif chemokine (CCL20), CCL7 as well as high mobility group box 1 and beta-site amyloid-β cleaving enzyme 1; and no effect was observed on the expression of neurotoxicity genes, including amyloid precursor protein, choline O-acetyltransferase, tumor necrosis factor, alpha-induced protein 1, B-cell lymphoma 2 and estrogen receptor 2. In addition, we observed elevated phosphorylation of cAMP response element-binding protein in DM mice exposed to sevoflurane anesthesia. In conclusion, sevoflurane did not exacerbate DM-associated cognitive impairment.

Interfering TRIB3 protects the blood brain barrier through PI3K/Akt pathway to alleviate cerebral ischemia-reperfusion injury in diabetes mellitus mice

This study aimed to treat diabetic cerebral ischemia-reperfusion injury (CI/RI) by affecting blood brain barrier (BBB) permeability and integrity. The CI/RI model in DM mice and a high glucose (HG) treated oxygen and glucose deprivation/reoxygenation (OGD/R) brain endothelial cell model were established for the study. Evans blue (EB) staining was used to evaluate the permeability of BBB in vivo. TTC staining was used to analyze cerebral infarction. The location and expression of tribbles homolog 3 (TRIB3) in endothelial cells were detected by immunofluorescence. Western blotting was used to detect the protein expressions of TRIB3, tight junction molecules, adhesion molecules, phosphorylated protein kinase B (p-AKT) and AKT. The levels of pro-inflammatory cytokines were detected by qRT-PCR. Trans-epithelial electrical resistance (TEER) and fluorescein isothiocyanate (FITC)-dextran were used to measure vascular permeability in vitro. TRIB3 ubiquitination and acetylation levels were detected. Acetyltransferase bound to TRIB3 were identified by immunoprecipitation. TRIB3 was localized in cerebral endothelial cells and was highly expressed in diabetic CI/R mice. The BBB permeability in diabetic CI/R mice and HG-treated OGD/R cells was increased, while the junction integrity was decreased. Interference with TRIB3 in vitro reduces BBB permeability and increases junction integrity. In vivo interfering with TRIB3 reduced cerebral infarction volume, BBB permeability and inflammation levels, and upregulated p-AKT levels. The phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin reversed the effects of TRIB3-interfering plasmid. In vitro HG treatment induced TRIB3 acetylation through acetyltransferase p300, which in turn reduced ubiquitination and stabilized TRIB3. Interfering TRIB3 protects BBB by activating PI3K/AKT pathway and alleviates brain injury, which provides a new target for diabetic CI/RI.

ACMSD mediated de novo NAD+ biosynthetic impairment in cardiac endothelial cells as a potential therapeutic target for diabetic cardiomyopathy

Object: The highly conserved α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD) is the key enzyme that regulates the de novo NAD+ synthesis from tryptophan. NAD+ metabolism in diabetic cardiomyopathy (DCM) was not elucidated yet. MethodsMice were assigned to non-diabetic (NDM) group, streptozocin (STZ)-induced diabetic (DM) group, and nicotinamide (NAM) treated (DM+NAM) group. ACMSD mediated NAD+ metabolism were studied both in mice and patients with diabetes. ResultsNAD+ level was significantly lower in the heart of DM mice than that of the NDM group. Supplementation with NAM could partially increased myocardial capillary density and ameliorated myocardial fibrosis by increasing NAD+ level through salvage pathway. Compared with NDM mice, the expression of ACMSD in myocardial endothelial cells of DM mice was significantly increased. It was further confirmed that in endothelial cells, high glucose promoted the expression of ACMSD. Inhibition of ACMSD could increase de novo NAD+ synthesis and improve endothelial cell function by increasing Sirt1 activity. Targeted mass spectrometry analysis indicated increased ACMSD enzyme activity in diabetic patients, higher ACMSD activity increased risk of heart diastolic dysfunction. ConclusionIn summary, increased expression of ACMSD lead to impaired de novo NAD+ synthesis in diabetic heart. Inhibition of ACMSD could potentially improve DCM.

Biomineralized ceria nanoparticles target the heart to improve diabetic cardiac remodeling by regulating mitochondrial oxidative stress and decreasing excessive mitophagy

Abstract Background An altered state of cardiomyocytes due to high glucose concentrations results in cell hypertrophy, leading to diabetic cardiomyopathy (DCM).The molecular regulatory process of mitochondrial dyshomeostasis and mitophagy, oxidative stress, and reactive oxygen species (ROS) production in diabetes is still not fully understood. Mitochondrial dyshomeostasis and mitophagy could be critical factors in the heart remodeling that occurs in diabetes. Purpose Our transcriptome sequencing of heart tissue revealed upregulation of the gene encoding the transferrin receptor (TfR) in the diabetic rat (Figure 1A). We then validated in vitro that high glucose increased TfR protein expression in the HL-1 cell line (Figure 1B). Herein, we developed a novel therapeutic ceria nanoparticle via biomineralization using transferrin (Tf) protein as a temple and assessed its targeted therapy for DM-induced cardiac remodeling via Tf-TfR mediated endocytosis. Method We synthesized Tf protein-based ceria NPs (CeO2@Tf) via biomineralization. Then the physicochemical and biological properties of NPs were characterized. Cellular uptake, cytotoxicity test, intracellularmitochondrial membrane potential (MMP), and ROS were verified with mouse cardiomyocytes HL-1 cells line. Afterward, the male C57BL/6N mice were randomly divided into control, DM, DM+Metformin (Met), and DM+NPs groups with eight weeks of treatment. Heart structure and function were measured by echocardiographic. The heart tissues were stained with hematoxylin, eosin (H&E), and Masson's trichrome stain to observe morphological changes and fibrosis. Western blot was used to determine mitochondrial homeostasis regulation-related proteins and mitophagy pathway. Results TEM and X-ray photoelectron spectroscopy characterized the properties successfully. MTT assay shows that HL-1 cell viabilities were not influenced by CeO2@Tf at 200 µM.High-glucose treatment led to increased ROS and decreased intracellular MMP in HL-1 cells. DM mice cardiac transcriptome sequencing results showed upregulation of transferrin receptor gene expression. Echocardiographic showed increased LAD and abnormal diastolic and systolic functions. All these abnormal changes were improved in the DM+ Met and DM+NPs groups. Our investigations revealed proteins linked to the PINK1-Parkin signaling pathway (Figure 2A-B) and found that the level of mitophagy in the diabetic group was overly high, which was improved after the application of CeO2@Tf. We observed the mitochondrial autophagosomes through transmission electron microscopy (Figure 2C). The autophagosomes in the diabetic group increased significantly and improved after treatment with CeO2@Tf. Conclusions These consistent biochemical and histopathological results suggest that the biomimetic mineralization of CeO2@Tf could inhibit oxidative stress and improve mitochondrial function in vitro induced by high-glucose and in vivo caused by DM, alleviating cardiac remodeling in DM mice.

Abstract 16084: Impairment of Cardio-Spleno-Bone Marrow Axis Following Myocardial Infarction in Diabetes Mellitus

Introduction: Precise comprehension of the cardio-spleen-bone-marrow immune cells axis is crucial to understanding the changes occurring during diabetes (DM) pathogenesis. This study aims to investigate the alterations in immune cell kinetics in DM after myocardial infarction (MI). Methods: MI was induced in DM and healthy control using C57BL/N6 mice. Animals were sacrificed at D1, D3, D7, & D28 post-MI to obtain their heart, peripheral blood (PB), spleen, and bone marrow (BM) and then each organ cell suspension was isolated, and analyzed by flow cytometry. EPC-colony-forming assay (EPC-CFA) was performed using BM, PB, and spleen-derived MNCs. Results: Findings demonstrated that despite the normal production of BM, CD45+ cells are decreased at D1-D3 in spleen and PB of DM’s. Further analysis depicted that total and pro-inflammatory neutrophil (N1) decreased at D1-D3 in PB and spleen at D3-D7 in DM mice, suggesting that DM causes spleen's neutrophil alterations that cannot compensate for PB and ischemia tissue demand. Infiltrated macrophages (total, M1, M2) decreased at D3 in DM-ischemic heart. Total and M1 (D1-D3) and M2 (D3-D7) notably decreased in DM-PB than control group, showing impaired macrophage recruitment/polarization in DM. Moreover, heart myeloid dendritic cells (mDCs) increased from D1-D7, the latter enhanced recruitment of CD8 cells increase from D1 to D28 in DM-infarcted-myocardium. The total CD4 cells decreased at D1-D3 in DM-PB, indicating a delayed adaptive immune response to MI. The B-cells diminished at D1-D3 in PB, at D3 in myocardium, and D7 in spleen, indicating impaired mobilization of those cells from bone marrow to compensate. EPC-CFA demonstrated dramatically decrease of definitive EPC colonies in spleen and BM from D1-D28 in DM mice vs control in vitro , indicating that DM significantly impairs EPC colony-forming bioactivity by limiting EPCs' differentiation from primitive to definitive. Conclusion: Our study highlights significant alterations of cardio-spleno-bone-marrow immune cells axis following MI in DM animals, revealing delayed innate/adaptive immune responses and impaired differentiation of EPCs.

Abstract 13173: Loss of ACE2 in a Diabetic Obese Setting Exacerbates Cardiovascular Dysfunction in the Setting of Gut Dysbiosis

Introduction: COVID-19 disproportionately affects older, male obese patients leading to a high prevalence of adverse outcomes. SARS-CoV-2 mediated ACE2 loss may further increase the susceptibility of these patients to adverse outcomes. Loss of ACE2 may be a causative factor in cardiovascular (CV) injury independent of primary viral-mediated injury. Methods: Male, 6-month-old, diabetic, obese db/db Ace2 -/y (double mutant, DM) mice and respective WT, Ace2 -/y , and db/db controls (n=12) were assessed for injury across the gut-heart axis. Cardiovascular parameters were evaluated by echocardiography, pressure-volume loops, and histology. Alterations in gut permeability were determined by measuring plasma peptidoglycan (PGN) levels and immunological staining of microvilli structure. Metagenomics and metatranscriptomics determined the functional and phyla alterations of the gut microbiota. Results: Loss of ACE2 in diabetic obese mice led to increased left atrium diameter (P<0.001) and elevated left ventricular end-diastolic pressures (P<0.05) compared to db/db mice. Cardiac remodeling was prevalent in DM hearts with increased cardiomyocyte hypertrophy (P<0.001), cardiac fibrosis (P<0.05), lipid accumulation (P<0.01), and reactive oxygen species (ROS; P<0.01) compared to db/db mice. This was associated with elevated aortic ROS (P<0.001), and impaired femoral artery vasodilation (P<0.001). DM mice had increased gut-blood barrier permeability, with elevated plasmalemma vesicle-associated protein-1 staining (P<0.05) and plasma PGN levels (P<0.01). Principal coordinates analysis of gut microbial β diversity showed distinct populations across the experimental groups (P<0.05). Loss of ACE2 in db/db mice resulted in the divergence of metatranscriptomics profiles with increased expression of neutral amino acid metabolism, PGN and toxin production pathways. Conclusions: Loss of ACE2 in diabetic obese mice worsened cardiovascular dysfunction and adverse remodeling and was associated with an altered gut-cardiovascular axis characterized by elevated gut permeability and dysbiosis. Our results support worsening CV injury arising from the loss of ACE2 and may indicate a pathway of SARS-CoV-2 infection mediated CV injury.

Non-steroidal mineralocorticoid receptor antagonist finerenone ameliorates mitochondrial dysfunction via PI3K/Akt/eNOS signaling pathway in diabetic tubulopathy

Diabetic tubulopathy (DT) is a recently recognized key pathology of diabetic kidney disease (DKD). The mitochondria-centric view of DT is emerging as a vital pathological factor in different types of metabolic diseases, such as DKD. Finerenone (FIN), a novel non-steroidal mineralocorticoid receptor antagonist, attenuates kidney inflammation and fibrosis in DKD, but the precise pathomechanisms remain unclear. The role of mineralocorticoid receptor (MR) in perturbing mitochondrial function via the PI3K/Akt/eNOS signaling pathway, including mitochondrial dynamics and mitophagy, was investigated under a diabetic state and high glucose (HG) ambiance. To elucidate how the activation of MR provokes mitochondrial dysfunction in DT, human kidney proximal tubular epithelial (HK-2) cells were exposed to HG, and then mitochondrial dynamics, mitophagy, mitochondrial ROS (mitoROS), signaling molecules PI3K, Akt, Akt phosphorylation and eNOS were probed. The above molecules or proteins were also explored in the kidneys of diabetic and FIN-treated mice. FIN treatment reduced oxidative stress, mitochondrial fragmentation, and apoptosis while restoring the mitophagy via PI3K/Akt/eNOS signaling pathway in HK-2 cells exposed to HG ambiance and tubular cells of DM mice. These findings linked MR activation to mitochondrial dysfunction via PI3K/Akt/eNOS signaling pathway in DT and highlight a pivotal but previously undiscovered role of FIN in alleviating renal tubule injury for the treatment of DKD.

FRI625 Diabetic Ischemic Skeletal Muscle Injury Occurs Through Pkc-beta/sp1 Regulation Of Bag3 Expression

Abstract Disclosure: A. Mani: None. V. Lamin: None. T. Wong: None. M.V. Singh: None. A.O. Dokun: None. Peripheral arterial disease (PAD) affects more than 200 million people worldwide and is characterized by impaired blood flow to the lower extremities. Individuals with diabetes (DM) and PAD have more severe ischemic limb injuries and increased limb amputations, but the mechanisms involved are poorly understood. Following experimental PAD, C57Bl/6 mice develop limited ischemic limb injury largely due to protective effect of genes within the limb salvage QTL-1 (LSq-1) a genetic locus on chromosome 7. However, when diabetes is induced in C57Bl/6 mice they develop severe ischemic limb injuries following experimental PAD, akin to the findings in humans. Previously, we identified BAG3 as a gene within LSq-1 that is protective against ischemic limb injuries. BAG3 is upregulated in ischemic limbs from non-DM C57Bl/6 mice but poorly expressed in ischemic limbs of DM mice. The mechanism of BAG3 upregulation in ischemia is not known however the BAG3 promoter has a Specificity protein 1 (Sp1) transcription factor binding site suggesting its possible role. Moreover, how DM impairs BAG3 expression in ischemic skeletal muscles in not known. PKCβ regulates expression of transcription factors, and its phosphorylation has been implicated in the vascular pathology in DM but a role in ischemic diabetic skeletal muscle injury has not been established. Here we assessed the role of Sp1 in BAG3 upregulation in ischemic skeletal muscle cells (HSMC), we found Sp1 is upregulated in ischemic HSMCs and overexpression of Sp1 enhanced BAG3 promoter luciferase activity while knock down of Sp1 impaired BAG3 upregulation in ischemia. However, in vitro, ischemic HSMCs under DM conditions (High glucose or HG, 25mM + Palmitic acid or PA, 200µM) express lower BAG3 (fold change: Vehicle, 1.0±0.02 vs HG+PA, 0.57±0.04; n=4; p<0.05) and Sp1 (fold change: Vehicle, 1.0±0.15 vs HG+PA, 0.22±0.03; n=4; p<0.05). Overexpression of BAG3 improved survival of ischemic HSMCs in DM conditions in vitro (fold change: Vehicle, 1.0±0.02 vs HG+PA, 1.3±0.02 vs BAG3+HG+PA, 1.03±0.03; n=4-5; p<0.05) and improved extent of limb injury in vivo (Necrosis Score; DM mice without BAG3 2.67±0.29 vs DM mice + BAG3, 0.87±0.29; n=8-9; p<0.05). Additionally, under DM conditions ischemic HSMCs showed increased phosphorylation of PKCβ on the Ser661. Blocking PKCβ activation with Ruboxistaurin (Rbx), a specific inhibitor of PKCβ phosphorylation prevented the DM induced phosphorylation of PKCβ on the Ser661 (p-PKCβ/PKCβ ratio: Vehicle, 0.08±0.006 vs HG±PA, 0.19±0.03 vs Rbx+HG+PA, 0.10±0.006; n=4; p<0.05) and rescued BAG3 and Sp1 expression (BAG3, fold change: Vehicle, 1.0±0.06 vs HG±PA, 0.50±0.02 vs Rbx+HG+PA, 0.76±0.03; SP1, fold change: Vehicle, 1.0±0.02 vs HG±PA, 0.57±0.03 vs Rbx+HG+PA, 0.85±0.02; n=4; p<0.05). We conclude that impaired BAG3 expression in ischemic HSMC is mediated by impaired Sp1 expression due to increased PKCβ phosphorylation in DM. Presentation: Friday, June 16, 2023

Tanshinone ⅡA activates PI3K/AKT signaling pathway to inhibit the apoptosis of mice cochlear pericytes induced by high glucose

Objective: To investigate whether tanshinone ⅡA can protect the apoptosis of mice cochlear pericytes induced by high glucose and its specific protective mechanism, so as to provide experimental evidence for the prevention and treatment of diabetic hearing loss. Methods: C57BL/6J male mice were used to prepare type 2 diabetes model, which were divided into normal (NG) group, diabetic (DM) group, diabetic+tanshinone ⅡA (HG+tanshinone ⅡA) group and tanshinone ⅡA group. Each group had 10 animals. Primary cochlear pericytes were divided into NG group, HG group (high glucose 35 mmol/L), HG+tanshinone ⅡA (1, 3, 5 μmol/L) group, HG+Tanshinone ⅡA+LY294002 (PI3K/AKT pathway inhibitor) group, LY294002 group, tanshinone ⅡA group and DMSO group. Auditory brainstem response (ABR) was used to measure hearing threshold. Evans blue was used to detect the permeability of blood labyrinth barrier in each group. TBA methods were used to detect oxidative stress levels in various organs of mice. Morphological changes of stria vascularis were observed by hematoxylin-eosin staining (HE). Evans blue was used to detect the vascular labyrinth barrier permeability in cochlea. The expression of apoptosis protein in stria vascularis pericytes was observed by immunofluorescence. Pericytes apoptosis rate was observed by flow cytometry. DCFH-DA was combined with flow cytometry to detect intracellular ROS content, and Western blot was used to detect the expression of apoptotic proteins (Cleaved-caspase3, Bax), anti-apoptotic proteins (BCL-2) and pathway proteins (PI3K, p-PI3K, AKT, p-AKT). SPSS software was used for statistical analysis. Independent sample t test was performed, and P<0.05 was considered statistically significant. Results: Animal experiments: Tanshinone ⅡA decreased the hearing threshold of DM group [(35.0±3.5) dB SPL vs. (55.3±8.1) dB SPL] (t=4.899, P<0.01), decreased the oxidative stress level in cochlea (t=4.384, P<0.05), improved the structure disorder, atrophy of cochlea vascular lines, vacuole increased phenomenon. Tanshinone ⅡA alleviated the increased permeability of the blood labyrinth barrier [Evans blue leakage (6.84±0.27) AU vs. (8.59±0.85) AU] in the cochlea of DM mice (t=2.770, P<0.05), reversed the apoptotic protein: Caspase3 (t=4.956, P<0.01) and Bax (t=4.388, P<0.05) in cochlear vascularis. Cell experiments: Tanshinone ⅡA decreased intracellular ROS content in a concentration-dependent way (t=3.569, P<0.05; t=4.772, P<0.01; t=7.494, P<0.01); Tanshinone ⅡA decreased apoptosis rate and apoptotic protein, and increased the expression of anti-apoptotic protein, p-PI3K/PI3K and p-AKT/AKT in concentration-dependent manner (all P values<0.05); LY294002 reversed the protective effect of tanshinone ⅡA on pericytes apoptosis (all P values<0.05). Conclusion: Tanshinone ⅡA can inhibit the apoptosis of cochlear pericytes induced by high glucose by reducing oxidative stress level and activating PI3K/AKT signaling pathway under high glucose environment, thus playing a protective role in diabetic hearing loss.