T1DM Mice Research Articles

#2599 Adam17 inhibition moderates interstitial fibrosis and macrophage infiltration in TD1 mouse model

Abstract Background and Aims ADAM17 participates in the release into circulation of inflammatory and fibrotic molecules, such as TNF-α actively involved in the progression of Diabetic Nephropathy. We studied the effect of specific deletion of ADAM17 in the endothelium and renal tubule in a T1 diabetic mouse model demonstrating its participation in the progression of kidney damage. As ADAM17 is also expressed in other cell types we wanted to study the effect of the complete deletion of Adam17 in type 1 diabetic mouse. Method We studied total inducible (by TAM) Adam17 knockout male mice (ADAM17KO) and their control littermates. Animals were rendered diabetic by STZ injection (DB group). Blood glucose, mesangial index (PAS staining), number of podocytes and positive area of α-SMA (by immunohistochemistry) were determined. We also studied the protein expression of the cytokine MCP-1 in renal cortex by Western Blot. Results The mesangial index value observed in the 20wk-DB group was compared with the diabetic ADAM17KO group. In the latter, the value significantly decreased. Podocyte loss detected in DB group was not observed in the KO-DB group. For interstitial fibrosis, the intensity and location of α-SMA was significantly lower in the ADAM17KO group. In addition, complete deletion of Adam17 partly prevented the infiltration of macrophages assessed by the expression of MCP-1 in the protein extract of the renal cortex. Conclusion Complete inhibition of Adam17 expression in T1DM mice prevents fibrosis progression and protects the glomerulus from hypertrophy. At the same time, it reduces macrophage infiltration, limiting the inflammatory response induced by diabetes. We demonstrate the influence of Adam17 on macrophages to reduce the expression of TNF-a partly responsible for the progression of diabetic nephropathy.

Skeletal muscle myosin heavy chain expression and 3D capillary network changes in streptozotocin-induced diabetic female mice.

It is not well-understood how type 1 diabetes (T1DM) affects skeletal muscle histological phenotype, particularly capillarisation. This study aimed to analyze skeletal muscle myosin heavy chain (MyHC) fibre type changes and 3D capillary network characteristics in experimental T1DM mice. Female C57BL/6J-OlaHsd mice were categorized into streptozotocin (STZ)-induced diabetic (n = 12) and age-matched non-diabetic controls (n =12). The muscle fibre phenotype of the soleus, gluteus maximus, and gastrocnemius muscles were characterized based on the expression of MyHC isoforms, while capillaries of the gluteus maximus were assessed with immunofluorescence staining, confocal laser microscopy and 3D image analysis. STZ-induced diabetic mice exhibited elevated glucose levels, reduced body weight, and prolonged thermal latency, verifying the T1DM phenotype. In both T1DM and non-diabetic mice, the gluteus maximus and gastrocnemius muscles predominantly expressed fast-twitch type 2b fibers, with no significant differences noted. However, the soleus muscle in non-diabetic mice had a greater proportion of type 2a fibers and comparable type 1 fiber densities (26.2 ± 14.6% vs 21.9 ± 13.5%) relative to diabetic mice. T1DM mice showed reduced fiber diameters (P = 0.026), and the 3D capillary network analysis indicated a higher capillary length per muscle volume in the gluteus maximus of diabetic mice compared to controls (P < 0.05). Overall, T1DM induced significant changes in the skeletal muscle, including shifts in MyHC fibre types, decreased fibre diameters, and increased relative capillarisation, possibly due to muscle fibre atrophy. Our findings emphasize the superior detail provided by the 3D analytical method for characterizing skeletal muscle capillary architecture, highlighting caution in interpreting 2D data for capillary changes in T1DM.

Novel Angiogenesis Role of GLP-1(32-36) to Rescue Diabetic Ischemic Lower Limbs via GLP-1R-Dependent Glycolysis in Mice.

Restoring the capacity of endothelial progenitor cells (EPCs) to promote angiogenesis is the major therapeutic strategy of diabetic peripheral artery disease. The aim of this study was to investigate the effects of GLP-1 (glucagon-like peptide 1; 32-36)-an end product of GLP-1-on angiogenesis of EPCs and T1DM (type 1 diabetes) mice, as well as its interaction with the classical GLP-1R (GLP-1 receptor) pathway and its effect on mitochondrial metabolism. In in vivo experiments, we conducted streptozocin-induced type 1 diabetic mice as a murine model of unilateral hind limb ischemia to examine the therapeutic potential of GLP-1(32-36) on angiogenesis. We also generated Glp1r-/- mice to detect whether GLP-1R is required for angiogenic function of GLP-1(32-36). In in vitro experiments, EPCs isolated from the mouse bone marrow and human umbilical cord blood samples were used to detect GLP-1(32-36)-mediated angiogenic capability under high glucose treatment. We demonstrated that GLP-1(32-36) did not affect insulin secretion but could significantly rescue angiogenic function and blood perfusion in ischemic limb of streptozocin-induced T1DM mice, a function similar to its parental GLP-1. We also found that GLP-1(32-36) promotes angiogenesis in EPCs exposed to high glucose. Specifically, GLP-1(32-36) has a causal role in improving fragile mitochondrial function and metabolism via the GLP-1R-mediated pathway. We further demonstrated that GLP-1(32-36) rescued diabetic ischemic lower limbs by activating the GLP-1R-dependent eNOS (endothelial NO synthase)/cGMP/PKG (protein kinase G) pathway. Our study provides a novel mechanism with which GLP-1(32-36) acts in modulating metabolic reprogramming toward glycolytic flux in partnership with GLP-1R for improved angiogenesis in high glucose-exposed EPCs and T1DM murine models. We propose that GLP-1(32-36) could be used as a monotherapy or add-on therapy with existing treatments for peripheral artery disease. URL: www.ebi.ac.uk/metabolights/; Unique identifier: MTBLS9543.

Abaloparatide is more potent than teriparatide in restoring bone mass and strength in type 1 diabetic male mice

This study investigated the efficacy of the two FDA-approved bone anabolic ligands of the parathyroid hormone receptor 1 (PTH1R), teriparatide or human parathyroid hormone 1–34 (PTH) and abaloparatide (ABL), to restoring skeletal health using a preclinical murine model of streptozotocin-induced T1-DM. Intermittent daily subcutaneous injections of equal molar doses (12 pmoles/g/day) of PTH (50 ng/g/day), ABL (47.5 ng/g/day), or vehicle, were administered for 28 days to 5-month-old C57Bl/6 J male mice with established T1-DM or control (C) mice. ABL was superior to PTH in increasing or restoring bone mass in control or T1-MD mice, respectively, which was associated with superior stimulation of trabecular and periosteal bone formation, upregulation of osteoclastic/osteoblastic gene expression, and increased circulating bone remodeling markers. Only ABL corrected the reduction in ultimate load, which is a measure of bone strength, induced by T1-DM, and it also increased energy to ultimate load. In addition, bones from T1-DM mice treated with PTH or ABL exhibited increased ultimate stress, a material index, compared to T1-DM mice administered with vehicle. And both PTH and ABL prevented the increased expression of the Wnt antagonist Sost/sclerostin displayed by T1-DM mice. Further, PTH and ABL increased to a similar extent the circulating bone resorption marker CTX and the bone formation marker P1NP in T1-DM after 2 weeks of treatment; however, only ABL sustained these increases after 4 weeks of treatment. We conclude that at equal molar doses, ABL is more effective than PTH in increasing bone mass and restoring the cortical and trabecular bone lost with T1-DM, due to higher and longer-lasting increases in bone remodeling.

Dynamic changes in cardiac morphology, function, and diffuse myocardial fibrosis duration of diabetes in type 1 and type 2 diabetic mice models using 7.0 T CMR and echocardiography.

Diabetes mellitus (DM) is associated with an increased risk of cardiovascular disease (CVD). Hence, early detection of cardiac changes by imaging is crucial to reducing cardiovascular complications. Early detection of cardiac changes is crucial to reducing cardiovascular complications. The study aimed to detect the dynamic change in cardiac morphology, function, and diffuse myocardial fibrosis(DMF) associated with T1DM and T2DM mice models. 4-week-old C57Bl/6J male mice were randomly divided into control (n=30), T1DM (n=30), and T2DM (n=30) groups. A longitudinal study was conducted every 4 weeks using serial 7.0T CMR and echocardiography imaging. Left ventricular ejection fraction (LV EF), tissue tracking parameters, and DMF were measured by cine CMR and extracellular volume fraction (ECV). Global peak circumferential strain (GCPS), peak systolic strain rate (GCPSSR) values were acquired by CMR feature tracking. LV diastolic function parameter (E/E') was acquired by echocardiography. The correlations between the ECV and cardiac function parameters were assessed by Pearson's test. A total of 6 mice were included every 4 weeks in control, T1DM, and T2DM groups for analysis. Compared to control group, an increase was detected in the LV mass and E/E' ratio, while the values of GCPS, GCPSSR decreased mildly in DM. Compared to T2DM group, GCPS and GCPSSR decreased earlier in T1DM(GCPS 12W,P=0.004; GCPSSR 12W,P=0.04). ECV values showed a significant correlation with GCPS and GCPSSR in DM groups. Moreover, ECV values showed a strong positive correlation with E/E'(T1DM,r=0.757,P<0.001;T2DM, r=0.811,P<0.001). The combination of ECV and cardiac mechanical parameters provide imaging biomakers for pathophysiology, early diagnosis of cardiac morphology, function and early intervention in diabetic cardiomyopathy in the future.

RETRACTED: Non-neuronal cholinergic system delays cardiac remodelling in type 1 diabetes

AimsType 1 diabetes mellitus (T1DM) is associated with increased risk of cardiovascular disease (CVD) and mortality. The underlying mechanisms for T1DM-induced heart disease still remains unclear. In this study, we aimed to investigate the effects of cardiac non-neuronal cholinergic system (cNNCS) activation on T1DM-induced cardiac remodelling. MethodsT1DM was induced in C57Bl6 mice using low-dose streptozotocin. Western blot analysis was used to measure the expression of cNNCS components at different time points (4, 8, 12, and 16 weeks after T1DM induction). To assess the potential benefits of cNNCS activation, T1DM was induced in mice with cardiomyocyte-specific overexpression of choline acetyltransferase (ChAT), the enzyme required for acetylcholine (Ac) synthesis. We evaluated the effects of ChAT overexpression on cNNCS components, vascular and cardiac remodelling, and cardiac function. Key findingsWestern blot analysis revealed dysregulation of cNNCS components in hearts of T1DM mice. Intracardiac ACh levels were also reduced in T1DM. Activation of ChAT significantly increased intracardiac ACh levels and prevented diabetes-induced dysregulation of cNNCS components. This was associated with preserved microvessel density, reduced apoptosis and fibrosis, and improved cardiac function. SignificanceOur study suggests that cNNCS dysregulation may contribute to T1DM-induced cardiac remodelling, and that increasing ACh levels may be a potential therapeutic strategy to prevent or delay T1DM-induced heart disease.

FTZ promotes islet β-cell regeneration in T1DM mice via the regulation of nuclear proliferation factors

Ethnopharmacological relevanceFufang-Zhenzhu-Tiaozhi capsule (FTZ), a Traditional Chinese Medicine (TCM) patent prescription commonly used in clinical practice, has a significant curative effect on hyperglycemia and hyperlipidemia. Previous studies have shown that FTZ can treat diabetes, but the effect of FTZ on β-cell regeneration needs to be further explored in T1DM mice. Aim of the studyThe aim is to investigate the role of FTZ in promoting β-cell regeneration in T1DM mice, and to further explore its mechanism. Materials and methodsC57BL/6 mice were used as control. NOD/LtJ mice were divided into the Model group and FTZ group. Oral glucose tolerance, fasting blood glucose, and fasting insulin level were measured. Immunofluorescence staining was used to detect the level of β-cell regeneration and the composition of α-cells and β-cells in islets. Hematoxylin and eosin staining was used to detect the infiltration degree of inflammatory cells. The apoptosis of islet cells was detected by terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling. Western blotting was used to detect the expression levels of Pancreas/duodenum homeobox protein 1 (PDX-1), V-maf musculoaponeurotic fibrosarcoma oncogene homolog A (MAFA), and Neurogenin-3 (NGN3). ResultsFTZ could increase insulin levels and reduce the glucose level of T1DM mice and promote β-cell regeneration. FTZ also inhibited the invasion of inflammatory cells and the islet cell apoptosis, and maintained the normal composition of islet cells, thus preserving the quantity and quality of β-cells. Furthermore, FTZ promoting β-cell regeneration was accompanied by increasing the expression of PDX-1, MAFA, and NGN3. ConclusionFTZ can restore the insulin-secreting function of the impaired pancreatic islet, improve blood glucose level, possibly via the enhancing β cell regeneration via upregulation of PDX-1, MAFA, and NGN3 in T1DM mice, and may be a potential therapeutic drug for T1DM.

The organic nitrate NDBP promotes cardiometabolic protection in type 1 diabetic mice

Studies from our laboratory have shown that the nitric oxide (NO) donor 2-nitrate-1,3-dibutoxypropan (NDBP) lowers blood pressure in hypertension. However, the role of NDBP in other cardiometabolic diseases such as diabetes remains unknown. Our study aimed to evaluate the cardiometabolic effect of NDBP treatment in type 1 diabetes (T1DM) mice. T1DM was induced by streptozotocin (i.p. 50 mg/kg, 5 days) and confirmed by fasting glucose (≥200 mg/dL). Following induction of T1DM, mice were treated with NDBP (40 mg/kg/day i.p.) or vehicle (cremophor in saline) for 14 days. Our data revealed that NDBP treatment in T1DM mice reduced hyperglycemia, water consumption, urine volume, and oxidative stress in the liver and pancreas and increased glucose tolerance. Furthermore, NDBP treatment improved vascular function, although it was not able to attenuate hypertension. In conclusion, our study results indicate that NDBP promotes beneficial metabolic effects and improves endothelium-independent vascular function in a mouse model of T1DM.

Remodeling of the periodontal ligament and alveolar bone during axial tooth movement in mice with type 1 diabetes.

To observe the elongation of the axial tooth movement in the unopposed rodent molar model with type 1 diabetes mellitus and explore the pathological changes of periodontal ligament and alveolar bone, and their correlation with tooth axial movement. The 80 C57BL/6J mice were randomly divided into the streptozotocin(STZ)-injected group (n = 50) and the control group (n = 30). Mice in the streptozotocin(STZ)-injected group were injected intraperitoneal with streptozotocin (STZ), and mice in the control group were given intraperitoneal injection of equal doses of sodium citrate buffer. Thirty mice were randomly selected from the successful models as the T1DM group. The right maxillary molar teeth of mice were extracted under anesthesia, and allowed mandibular molars to super-erupt. Mice were sacrificed at 0, 3, 6,9, and 12 days. Tooth elongation and bone mineral density (BMD) were evaluated by micro-CT analysis(0,and 12 days mice). Conventional HE staining, Masson staining and TRAP staining were used to observe the changes in periodontal tissue(0, 3, 6, 9, and 12 days mice). The expression differences of SPARC, FGF9, BMP4, NOGGIN, and type I collagen were analyzed by RT-qPCR. After 12 days of tooth extraction, our data showed significant super-eruption of mandibular mouse molars of the two groups. The amount of molar super-eruption in the T1DM group was 0.055mm( ± 0.014mm), and in the control group was 0.157( ± 0.017mm). The elongation of the T1DM mice was less than that of the control mice(P<0.001). It was observed that the osteoclasts and BMD increased gradually in both groups over time. Compared with the control group, the collagen arrangement was more disordered, the number of osteoclasts was higher (P<0.05), and the increase of bone mineral density was lower(2.180 ± 0.007g/cm3 vs. 2.204 ± 0.006g/cm3, P<0.001) in the T1DM group. The relative expression of SPARC, FGF9, BMP4, and type I collagen in the two groups increased with the extension of tooth extraction time while NOGGIN decreased. The relative expression of all of SPARC, FGF9, BMP4, and type I collagen in the T1DM group were significantly lower, and the expression of NOGGIN was higher than that in the control group (P<0.05). The axial tooth movement was inhibited in type 1 diabetic mice. The result may be associated with the changes of periodontal ligament osteoclastogenic effects and alveolar bone remodeling regulated by the extracellular matrix and osteogenesis-related factors.

Streptozotocin-Induced Type 1 and 2 Diabetes Mellitus Mouse Models Show Different Functional, Cellular and Molecular Patterns of Diabetic Cardiomyopathy.

The main cause of morbidity and mortality in diabetes mellitus (DM) is cardiovascular complications. Diabetic cardiomyopathy (DCM) remains incompletely understood. Animal models have been crucial in exploring DCM pathophysiology while identifying potential therapeutic targets. Streptozotocin (STZ) has been widely used to produce experimental models of both type 1 and type 2 DM (T1DM and T2DM). Here, we compared these two models for their effects on cardiac structure, function and transcriptome. Different doses of STZ and diet chows were used to generate T1DM and T2DM in C57BL/6J mice. Normal euglycemic and nonobese sex- and age-matched mice served as controls (CTRL). Immunohistochemistry, RT-PCR and RNA-seq were employed to compare hearts from the three animal groups. STZ-induced T1DM and T2DM affected left ventricular function and myocardial performance differently. T1DM displayed exaggerated apoptotic cardiomyocyte (CM) death and reactive hypertrophy and fibrosis, along with increased cardiac oxidative stress, CM DNA damage and senescence, when compared to T2DM in mice. T1DM and T2DM affected the whole cardiac transcriptome differently. In conclusion, the STZ-induced T1DM and T2DM mouse models showed significant differences in cardiac remodeling, function and the whole transcriptome. These differences could be of key relevance when choosing an animal model to study specific features of DCM.

Magnolol effectively ameliorates diabetic peripheral neuropathy in mice

BackgroundDiabetic peripheral neuropathy (DPN) is a common complication of diabetes lacking efficient treatment. Magnolol (MG), a peroxisome proliferator-activated receptor γ (PPARγ) agonist, is a natural product derived from Magnolia officinalis and widely used to treat a variety of diseases as a traditional Chinese medicine and Japanese Kampo medicine. PurposeHere, we aimed to investigate the potential of MG in ameliorating DPN-like pathology in mice and decipher the mechanism of MG in treating DPN. Materials and methods12-week-old male streptozotocin (STZ)-induced type 1 diabetic (T1DM) mice and 15-week-old male BKS Cg-m+/+Lepr db/J (db/db) type 2 diabetic mice (T2DM) were used as DPN mice. MG was administrated (i.p) daily for 4 weeks. Peripheral nerve functions of mice were evaluated by measuring mechanical response latency, thermal response latency and motor nerve conduction velocity (MNCV). The mechanisms underlying the amelioration of MG on DPN-like pathology were examined by qRT-PCR, western blot and immunohistochemistry assays, and verified in the DPN mice with PPARγ-specific knockdown in dorsal root ganglia (DRG) neuron and sciatic nerve tissues by injecting adeno-associated virus (AAV)8-PPARγ-RNAi. ResultsMG promoted DRG neuronal neurite outgrowth and effectively ameliorated neurological dysfunctions in both T1DM and T2DM diabetic mice, including improvement of paw withdrawal threshold, thermal response latency and MNCV. Additionally, MG promoted neurite outgrowth of DRG neurons, protected sciatic nerve myelin sheath structure, and ameliorated foot skin intraepidermal nerve fiber (IENF) density in DPN mice by targeting PPARγ. Mechanism research results indicated that MG improved mitochondrial dysfunction involving PPARγ/MKP-7/JNK/SIRT1/LKB1/AMPK/PGC-1α pathway in DRG neurons, repressed inflammation via PPARγ/NF-κB signaling and inhibited apoptosis through regulation of PPARγ-mediated Bcl-2 family proteins in DRG neurons and sciatic nerves. ConclusionsOur work has detailed the mechanism underlying the amelioration of PPARγ agonist on DPN-like pathology in mice with MG as a probe, and highlighted the potential of MG in the treatment of DPN.

Immunotherapy for type 1 diabetes mellitus by adjuvant-free Schistosoma japonicum-egg tip-loaded asymmetric microneedle patch (STAMP)

BackgroundType 1 diabetes mellitus (T1DM) is an autoimmune disease mediated by autoreactive T cells and dominated by Th1 response polarization. Insulin replacement therapy faces great challenges to this autoimmune disease, requiring highly frequent daily administration. Intriguingly, the progression of T1DM has proven to be prevented or attenuated by helminth infection or worm antigens for a relatively long term. However, the inevitable problems of low safety and poor compliance arise from infection with live worms or direct injection of antigens. Microneedles would be a promising candidate for local delivery of intact antigens, thus providing an opportunity for the clinical immunotherapy of parasitic products.MethodsWe developed a Schistosoma japonicum-egg tip-loaded asymmetric microneedle patch (STAMP) system, which serves as a new strategy to combat TIDM. In order to improve retention time and reduce contamination risk, a specific imperfection was introduced on the STAMP (asymmetric structure), which allows the tip to quickly separate from the base layer, improving reaction time and patient’s comfort. After loading Schistosoma japonicum-egg as the immune regulator, the effects of STAMP on blood glucose control and pancreatic pathological progression improvement were evaluated in vivo. Meanwhile, the immunoregulatory mechanism and biosafety of STAMP were confirmed by histopathology, qRT-PCR, ELISA and Flow cytometric analysis.ResultsHere, the newly developed STAMP was able to significantly reduce blood glucose and attenuate the pancreatic injury in T1DM mice independent of the adjuvants. The isolated Schistosoma japonicum-eggs micron slowly degraded in the skin and continuously released egg antigen for at least 2 weeks, ensuring localization and safety of antigen stimulation. This phenomenon should be attributed to the shift of Th2 immune response to reduce Th1 polarization.ConclusionOur results exhibited that STAMP could significantly regulate the blood glucose level and attenuate pancreatic pathological injury in T1DM mice by balancing the Th1/Th2 immune responses, which is independent of adjuvants. This technology opens a new window for the application of parasite products in clinical immunotherapy.

Effects of Porphyra yezoensis extract on hepatic inflammatory factors and oxidative stress in type 1 diabetic mice

To study the effect of Porphyra yezoensis extract on liver inflammation and oxidative stress in type 1 diabetics mice. A total of ninety-one C57 BL/6 J male mice were adaptively fed for two weeks, and twelve C57 BL/6 J male mice were randomly reserved to be included in the blank control group. The rest of the mice were fasted overnight for twelve hours(except water), and they were given 170.00 mg/kg streptozotocin by intraperitoneal injection. Fasting blood glucose in type 1 diabetics mice were greater than or equal to 16.7 mmol/L after seven days, and polydipsia, polyphagia, polyuria and weight loss appeared, which were judged to be the successful model of type 1 diabetes. Forty-eight successfully modeled mice were divided into the model control group, the low dose of Porphyra yezoensis extract group, the medium dose of Porphyra yezoensis extract and high dose of Porphyra yezoensis extract group according to the fasting blood glucose and body weight. The mice in the blank control group and the model group were given the same amount of normal saline. The low-dose, medium-dose, and high-dose intervention groups were separately given the corresponding dose of Porphyra yezoensis extract by intragastric administration for six weeks. The body weight of type 1 diabetic mice, changes in body length, fasting blood glucose, insulin, liver inflammatory factors and oxidative stress indicators and pathological sections of liver and pancreas after the intervention of Porphyra yezoensis extract were observed. The glucose oxidase method was used to determine the fasting blood glucose level of type 1 diabetic mice. The serum insulin content, liver inflammatory factor levels and oxidative stress indicators were detected by the enzyme-linked immunosorbent assay(ELISA). The hematoxylin-eosin staining method was used to observe histopathology of liver and pancreas paraffin sections. The weight of the model control group was significantly lower than that of the blank control group(P&lt;0.05), and the fasting blood glucose value was significantly higher than that of the blank control group(P&lt;0.05). There was no statistical difference. In terms of inflammatory factors, compared with the model control group, low-dose Porphyra yezoensis extract can increase serum insulin levels and reduce liver tumor necrosis factor-α(TNF-α) levels(P&lt;0.05) in T1DM mice, and medium-dose Porphyra yezoensis extract can reduce liver TNF-α level(P&lt;0.05), high-dose Porphyra yezoensis extract can reduce the level of interleukin-1β(IL-1β)(P&lt;0.05). The histopathological conditions of pancreas in different intervention groups were improved compared with the model control group, and the number of β cells increased compared with the model group. In terms of oxidative stress, compared with the model control group, low-dose Porphyra yezoensis extract can significantly reduce the levels of liver alanine aminotransferase(ALT) and malondialdehyde(MDA)(P&lt;0.05), and high-dose Porphyra yezoensis extract can significantly increase the levels of glutathione peroxidase(GSH-Px) and catalase(CAT)(P&lt;0.05). The protective effect of Porphyra yezoensis extract on liver oxidative damage in T1DM mice may be achieved by regulating the activity of CAT and GSH-Px and reducing the content of MDA. In addition, Porphyra yezoensis extract can reduce liver TNF-α and IL-1β levels to improve liver inflammation.

Preexisting Type 1 Diabetes Mellitus Blunts the Development of Posttraumatic Osteoarthritis.

ABSTRACTType 1 diabetes mellitus (T1DM) affects 9.5% of the population. T1DM is characterized by severe insulin deficiency that causes hyperglycemia and leads to several systemic effects. T1DM has been suggested as a risk factor for articular cartilage damage and loss, which could expedite the development of osteoarthritis (OA). OA represents a major public health challenge by affecting 300 million people globally, yet very little is known about the correlation between T1DM and OA. In addition, current studies that have looked at the interaction between diabetes mellitus and OA have reported conflicting results with some suggesting a positive correlation whereas others did not. In this study, we aimed to evaluate whether T1DM exacerbates the development of spontaneous OA or accelerates the progression of posttraumatic osteoarthritis (PTOA) after joint injury. Histological evaluation of T1DM and control joints determined that T1DM mice displayed cartilage degeneration measurements consistent with mild OA phenotypes. RNA sequencing analyses identified significantly upregulated genes in T1DM corresponding to matrix‐degrading enzymes known to promote cartilage matrix degradation, suggesting a role of these enzymes in OA development. Next, we assessed whether preexisting T1DM influences PTOA development subsequent to trauma. At 6 weeks post‐injury, T1DM injured joints displayed significantly less cartilage damage and joint degeneration than injured non‐diabetic joints, suggesting a significant delay in PTOA disease progression. At the single‐cell resolution, we identified increased number of cells expressing the chondrocyte markers Col2a1, Acan, and Cytl1 in the T1DM injured group. Our findings demonstrate that T1DM can be a risk factor for OA but not for PTOA. This study provides the first account of single‐cell resolution related to T1DM and the risk for OA and PTOA. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Formononetin attenuates osteoclast differentiation and calcium loss by mediating transcription factor AP-1 in type I diabetic mice.

Formononetin (FMN) has been reported as a prospective antiosteoporotic medication. However, the antiosteoporotic properties of FMN are still unclear in a mouse model with diabetes-induced osteoporosis.An osteoporotic or osteopenic mouse model with type I diabetes mellitus (T1DM) was established using streptozotocin (40 mg/kg) injection for 5 consecutive days. After 12 weeks with FMN intragastric administration (0.5, 5, 20 mg/kg), the antiosteoporotic activity of FMN was evaluated in T1DM mice.FMN supplementation effectively improves Ca excretion and trabecular bone degeneration and impedes osteoclast differentiation and function to attenuate hyperglycemia-induced bone deterioration. In addition, FMN inhibited activating protein 1 (AP-1) and osteoclast-specific gene expression, Nfatc1, Ctsk, and TRAP.The administration of FMN has a beneficial effect to attenuate hyperglycemia-induced bone deteriorations, including osteoclastogenesis, trabecular bone, and Ca loss. Our study provided a prospective medication for the treatment of T1DM-related osteopenia or osteoporosis with FMN.

Effect of spermidine on ameliorating spermatogenic disorders in diabetic mice via regulating glycolysis pathway

Diabetes mellitus (DM), a high incidence metabolic disease, is related to the impairment of male spermatogenic function. Spermidine (SPM), one of the biogenic amines, was identified from human seminal plasma and believed to have multiple pharmacological functions. However, there exists little evidence that reported SPM’s effects on moderating diabetic male spermatogenic function. Thus, the objective of this study was to investigate the SPM’s protective effects on testicular spermatogenic function in streptozotocin (STZ)-induced type 1 diabetic mice. Therefore, 40 mature male C57BL/6 J mice were divided into four main groups: the control group (n = 10), the diabetic group (n = 10), the 2.5 mg/kg SPM-treated diabetic group (n = 10) and the 5 mg/kg SPM-treated diabetic group (n = 10), which was given intraperitoneally for 8 weeks. The type 1 diabetic mice model was established by a single intraperitoneal injection of STZ 120 mg/kg. The results showed that, compare to the control group, the body and testis weight, as well the number of sperm were decreased, while the rate of sperm malformation was significantly increased in STZ-induced diabetic mice. Then the testicular morphology was observed, which showed that seminiferous tubule of testis were arranged in mess, the area and diameter of which was decreased, along with downregulated anti-apoptotic factor (Bcl-2) expression, and upregulated pro-apoptotic factor (Bax) expression in the testes. Furthermore, testicular genetic expression levels of Sertoli cells (SCs) markers (WT1, GATA4 and Vimentin) detected that the pathological changes aggravated observably, such as the severity of tubule degeneration increased. Compared to the saline-treated DM mice, SPM treatment markedly improved testicular function, with an increment in the body and testis weight as well as sperm count. Pro-apoptotic factor (Bax) was down-regulated expression with the up-regulated expression of Bcl-2 and suppression of apoptosis in the testes. What’s more, expression of WT1, GATA4, Vimentin and the expressions of glycolytic rate-limiting enzyme genes (HK2, PKM2, LDHA) in diabetic testes were also upregulated by SPM supplement. The evidence derived from this study indicated that the SMP’s positive effect on moderating spermatogenic disorder in T1DM mice’s testis. This positive effect is delivered via promoting spermatogenic cell proliferation and participating in the glycolytic pathway’s activation.

Effect of 4 Weeks of Moderate-Intensity Endurance Exercise and Lithium Administration on Blood Glucose Level in STZ-Induced Type 1 Diabetes Mellitus Mice

PURPOSE: The purpose of this study was to investigate the effects of short-term endurance exercise and lithium treatment on fasting blood glucose in rats with type 1 diabetes (T1DM).METHODS: Ten-week-old male C57BL/6J mice were induced with T1DM using streptozotocin (STZ) injection. They were then randomly assigned to five groups and treated for a total of 4 weeks. For lithium treatment, 10 mg/kg LiCl was orally administered once a day, 5 days a week, and endurance exercise was performed at 21 m/minutes for 60 minutes, 5 days a week. After four weeks of treatment, blood and the plantaris muscle were extracted under anesthesia, and blood glucose and biomolecular factors were analyzed.RESULTS: 4 weeks of moderate-intensity endurance exercise significantly reduced fasting blood glucose in T1DM mice, increased the expression of GLUT4 in skeletal muscle, and significantly decreased the expression of dynamin, a GLUT4 endocytosis-related factor. Endurance exercise significantly increased mitochondrial biosynthesis in the skeletal muscles and significantly reduced the expression of the MAPK family. However, no biochemical or physiological changes were associated with lithium alone or in combination.CONCLUSIONS: 4 weeks of moderate-intensity endurance exercise improves fasting blood sugar levels through positive changes in glycemic control factors in the skeletal muscle. However, lithium treatment has no resultant effect. These results are thought to have been influenced by the decrease in the expression of the MAPK family and the increase in mitochondrial biosynthesis by endurance exercise for 4 weeks. However, further research is required to establish a clear causal relationship.

Myeloid differential protein-2 inhibition improves diabetic cardiomyopathy via p38MAPK inhibition and AMPK pathway activation

Myeloid differential protein-2 (MD2) has been shown to play a critical role in the progression of diabetic cardiomyopathy (DCM). This study aims to explore the non-inflammatory mechanisms mediated by MD2 in DCM and to test the therapeutic effects of MD2 inhibitor C30 on DCM. Streptozotocin (STZ) was used to construct DCM model in wild-type and MD2 knockout mice. The collected heart samples were subjected to RNA-sequencing assay. Gene set enrichment analysis of the RNA-seq data indicated that MD2 knockout was associated with energy metabolism pathways in diabetic mouse heart. Further data showed that AMPK pathway was impaired under high glucose condition, which was mediated by p38MAPK activation. MD2 knockout or pharmacological inhibitor C30 completely rescued AMPK signaling through p38MAPK inhibition. Importantly, C30 treatment significantly prevented myocardial damage and dysfunction in T1DM mice evidenced by improved cardiac function and reduced cardiomyocyte apoptosis and cardiac fibrosis. Furthermore, the therapeutic effect of C30 on DCM was correlated to p38MAPK inhibition and AMPK pathway activation in vivo and in vitro. In conclusion, MD2 inhibition exhibits therapeutic effects on DCM through p38MAPK inhibition and AMPK activation, which enables MD2 a promising target for DCM treatment by suppressing metaflammation and improving cardiac metabolism.

IL-6 induced enhanced clearance of proANP and ANP by insulin-degrading enzyme in T1DM mice.

Cardiovascular disease (CVD) is a prevalent cause of morbidity and mortality in type I diabetes mellitus (T1DM). However, the pathophysiological mechanisms underlying the relationship between CVD, CVD risk factors, and T1DM have not yet been sufficiently explored. Here, we report that insulin-degrading enzyme (IDE) effectively degrades the precursor of atrial natriuretic peptide (proANP) in HEK293T cells. The pro-inflammatory cytokine IL-6 elicited a significant dose-dependent increase in IDE protein expression. Inhibition of the ERK/MAPK signaling pathway with selumetinib abolished the IL-6-stimulated increase in IDE protein levels and decreased ANP secretion in H9C2 cells. Importantly, the T1DM mouse model displayed lower proANP in the heart and ANP in serum, due to increased IDE expression and activity. Our results suggest a novel role of IL-6 in ANP metabolism via IDE and provide possibilities for new potential therapeutic strategies for diabetes-related cardiovascular complications.

SGLT2 Inhibition by Dapagliflozin Attenuates Diabetic Ketoacidosis in Mice with Type-1 Diabetes

SGLT2 inhibitors increase plasma ketone concentrations. It has been suggested that insulinopenia, along with an increase in the counter-regulatory hormones epinephrine, corticosterone, glucagon and growth hormone, can induce ketoacidosis, especially in type-1 diabetes (T1DM). Dehydration precipitates SGLT2 inhibitor-induced ketoacidosis in type-2 diabetes. We studied the effects of dapagliflozin and water deprivation on the development of ketoacidosis and the associated signaling pathways in T1DM mice. C57BL/6 mice were fed a high-fat diet. After 7days, some mice received intraperitoneal injection of streptozocin + alloxan (STZ/ALX). The treatment groups were control + water at lib; control + dapagloflozin + water at lib; control + dapagloflozin + water deprivation; STZ/ALX + water at lib; STZ/ALX + water deprivation; STZ/ALX + dapagloflozin + water at lib; STZ/ALX + dapagloflozin + water deprivation. Dapagliflozin was given for 7days. In the morning of day 18, food was removed, and water was removed in the water deprivation groups. ELISA, rt-PCR, and immunoblotting were used to assess blood, heart, liver, white and brown adipose tissues. The T1DM mice had ketoacidosis even without water deprivation. Water deprivation increased plasma levels of β-hydroxybutyrate, acetoacetate, corticosterone, and epinephrine and reduced the levels of adiponectin in T1DM mice. Interleukin (IL) 1β, IL-6, IL-8, and TNFα were also increased in the T1DM mice with water deprivation. Dapagliflozin attenuated the changes in the T1DM mice without and with water deprivation. Likewise, water deprivation increased the activation of the inflammasome in the heart, liver, and white fat of the T1DM mice and dapagliflozin attenuated these changes. Dapagliflozin reduced the mRNA levels of glucagon receptors in the liver and the increase in GPR109a in white and brown fat. In the liver, dapagliflozin increased AMPK phosphorylation, and attenuated the phosphorylation of TBK1 and the activation of NFκB. Dapagliflozin reduced ketone body levels and attenuated the activation of NFκB and the activation of the inflammasome in T1DM mice with ketoacidosis.