Mouse Model Of Type 1 Diabetes Research Articles

Reduced Follicular Regulatory T Cells in Spleen and Pancreatic Lymph Nodes of Patients With Type 1 Diabetes.

In the attempt to understand the origin of autoantibody (AAb) production in patients with and at risk for type 1 diabetes (T1D), multiple studies have analyzed and reported alterations in T follicular helper (Tfh) cells in presymptomatic AAb+ subjects and patients with T1D. Yet, whether the regulatory counterpart of Tfh cells, represented by T follicular regulatory (Tfr) cells, is similarly altered is still unclear. To address this question, we performed analyses in peripheral blood, spleen, and pancreatic lymph nodes (PLN) of organ donor subjects with T1D. Blood analyses were also performed in living AAb- and AAb+ subjects. While negligible differences in the frequency and phenotype of blood Tfr cells were observed among T1D, AAb-, and AAb+ adult subjects, the frequency of Tfr cells was significantly reduced in spleen and PLN of T1D as compared with nondiabetic control subjects. Furthermore, adoptive transfer of Tfr cells delayed disease development in a mouse model of T1D, a finding that could indicate that Tfr cells play an important role in peripheral tolerance and regulation of autoreactive Tfh cells. Together, our findings provide evidence of Tfr cell alterations within disease-relevant tissues in patients with T1D, suggesting a role for Tfr cells in defective humoral tolerance and disease pathogenesis.

Transient Depletion of Foxp3+ Regulatory T Cells Selectively Promotes Aggressive β Cell Autoimmunity in Genetically Susceptible DEREG Mice.

Type 1 diabetes (T1D) represents a hallmark of the fatal multiorgan autoimmune syndrome affecting humans with abrogated Foxp3+ regulatory T (Treg) cell function due to Foxp3 gene mutations, but whether the loss of Foxp3+ Treg cell activity is indeed sufficient to promote β cell autoimmunity requires further scrutiny. As opposed to human Treg cell deficiency, β cell autoimmunity has not been observed in non-autoimmune-prone mice with constitutive Foxp3 deficiency or after diphtheria toxin receptor (DTR)-mediated ablation of Foxp3+ Treg cells. In the spontaneous nonobese diabetic (NOD) mouse model of T1D, constitutive Foxp3 deficiency did not result in invasive insulitis and hyperglycemia, and previous studies on Foxp3+ Treg cell ablation focused on Foxp3DTR NOD mice, in which expression of a transgenic BDC2.5 T cell receptor (TCR) restricted the CD4+ TCR repertoire to a single diabetogenic specificity. Here we revisited the effect of acute Foxp3+ Treg cell ablation on β cell autoimmunity in NOD mice in the context of a polyclonal TCR repertoire. For this, we took advantage of the well-established DTR/GFP transgene of DEREG mice, which allows for specific ablation of Foxp3+ Treg cells without promoting catastrophic autoimmune diseases. We show that the transient loss of Foxp3+ Treg cells in prediabetic NOD.DEREG mice is sufficient to precipitate severe insulitis and persistent hyperglycemia within 5 days after DT administration. Importantly, DT-treated NOD.DEREG mice preserved many clinical features of spontaneous diabetes progression in the NOD model, including a prominent role of diabetogenic CD8+ T cells in terminal β cell destruction. Despite the severity of destructive β cell autoimmunity, anti-CD3 mAb therapy of DT-treated mice interfered with the progression to overt diabetes, indicating that the novel NOD.DEREG model can be exploited for preclinical studies on T1D under experimental conditions of synchronized, advanced β cell autoimmunity. Overall, our studies highlight the continuous requirement of Foxp3+ Treg cell activity for the control of genetically pre-installed autoimmune diabetes.

MiR-183 and miR-96 orchestrate both glucose and fat utilization in skeletal muscle.

Our knowledge of the coordination of fuel usage in skeletal muscle is incomplete. Whether and how microRNAs are involved in the substrate selection for oxidation is largely unknown. Here we show that mice lacking miR-183 and miR-96 have enhanced muscle oxidative phenotype and altered glucose/lipid homeostasis. Moreover, loss of miR-183 and miR-96 results in a shift in substrate utilization toward fat relative to carbohydrates in mice. Mechanistically, loss of miR-183 and miR-96 suppresses glucose utilization in skeletal muscle by increasing PDHA1 phosphorylation via targeting FoxO1 and PDK4. On the other hand, loss of miR-183 and miR-96 promotes fat usage in skeletal muscle by enhancing intramuscular lipolysis via targeting FoxO1 and ATGL. Thus, our study establishes miR-183 and miR-96 as master coordinators of fuel selection and metabolic homeostasis owing to their capability of modulating both glucose utilization and fat catabolism. Lastly, weshow that loss of miR-183 and miR-96 can alleviate obesity andimprove glucose metabolism in high-fat diet-induced mice, suggesting that miR-183 and miR-96 may serve as therapeutic targets for metabolic diseases.

Lipidomic analysis of meibomian glands from type-1 diabetes mouse model and preliminary studies of potential mechanism

Diabetes is a significant risk factor for meibomian gland dysfunction (MGD), but its mechanism is poorly understood. The main function of the meibomian glands (MGs) is to synthesize, store, and secrete lipids. In this study, we found that the amount of lipids in the meibomian acini in STZ-induced type 1 diabetic mice decreased, and the lipid droplets became larger and irregular. In all, 31 lipid subclasses were identified in the mouse MGs, which contained 1378 lipid species in total through lipidomics analysis based on LC-MS/MS. Diabetes caused a significant increase in the content of ceramides (Cer) in the MGs but a significant decrease in the ration of sphingomyelin to ceramides (SM/Cer). The quantity of meibocytes in diabetic mice was dramatically decreased, and the proliferation activity was alleviated, which may be associated with cell cycle arrest caused by diabetes-induced abnormal Cer metabolism in MGs. We found an increase in macrophage and neutrophils infiltration in the diabetic MGs, which may be related to the significant reduction of AcCa in diabetic MGs. Taken together, the results of the present study demonstrated that diabetes induced disruption of lipid homeostasis in MGs, which may mediate the decreased cell proliferation and increased inflammation caused by diabetes in MGs.

Smartphone-Flashlight-Mediated Remote Control of Rapid Insulin Secretion Restores Glucose Homeostasis in Experimental Type-1 Diabetes.

Emerging digital assessment of biomarkers by linking health-related data obtained from wearable electronic devices and embedded health and fitness sensors in smartphones is opening up the possibility of creating a continuous remote-monitoring platform for disease management. It is considered that the built-in flashlight of smartphones may be utilized to remotely program genetically engineered designer cells for on-demand delivery of protein-based therapeutics. Here, the authors present smartphone-induced insulin release in β-cell line (iβ-cell) technology for traceless light-triggered rapid insulin secretion, employing the light-activatable receptor melanopsin to induce calcium influx and membrane depolarization upon illumination. This iβ-cell-based system enables repeated, reversible secretion of insulin within 15min in response to light stimulation, with a high induction fold both in vitro and in vivo. It is shown that programmable percutaneous remote control of implanted microencapsulated iβ-cells with a smartphone's flashlight rapidly reverses hyperglycemia in a mouse model of type-1 diabetes.

121-LB: Glucose- and Glucagon-Lowering Effect of a Single Oral Leptin Dose in Type 1 Diabetes Patients

Recent understandings of the role of leptin in glucagon and glucose homeostasis, have flagged it as a target for management of type 1 diabetes (T1D). While historically thought to be involved in long-term regulation of appetite and energy expenditure, leptin is now known to regulate food absorption, mucus secretion, intestinal motility and inflammatory processes. Leptin was shown to directly inhibit glucose uptake and reduce glucagon levels and insulin requirements in NOD mice, to ameliorate hyperglycemia in a T1D mouse model, and reduce insulin requirements in patients with insulin-resistant diabetes. Leptin-based drugs are currently only available in injectable forms, and suffer from a short half-life in the circulation. ORMD-0701 is an oral leptin drug, specially formulated to protect the active ingredient from degradative forces in the gut and enhance its uptake across the intestinal mucosa. This first-in-human study assessed the short-term effects of a single ORMD-0701 dose (3 mg leptin) administered to fasting patients with T1D. Patients on an insulin pump and with glucose levels >100 mg% and <280 mg%, received an ORMD-0701 (n=7) or placebo (n=3) capsule. Basal insulin pump rates were then lowered to 50% of the regular program and blood glucose, glucagon and leptin levels were monitored for 3 h. Glucagon area under the curve 30-120-min post-treatment (AUC30-120) was 0.60 ng*min/L lower than baseline values, while it rose by 0.69 ng*min/L in the placebo group. Similar trends were recorded for glucose AUC30-120 measures, with an 0.43 mmol*min/L decrease from baseline AUC in the active group versus a 0.24 mmol*min/L increase in the placebo group. By the end of the monitoring period, glucose and glucagon levels returned to baseline levels in all patients. No significant changes in blood leptin levels were detected in either cohort. These preliminary findings set the stage for further assessment of oral leptin and its impact on normalizing the insulin-glucagon balance in patients with T1D. Disclosure M. Kidron: Employee; Self; Oramed Pharmaceuticals, Inc., Stock/Shareholder; Self; Oramed Pharmaceuticals, Inc. S. Perles: Employee; Self; Oramed Ltd. R. Weiss: Consultant; Self; Lilly Global Health Partnership, Medtronic, Speaker’s Bureau; Self; Novo Nordisk.

938-P: A Human Gut Commensal, Parabacteroides Distasonis, Enhances Type 1 Diabetes Autoimmunity via Molecular Mimicry

Type 1 diabetes (T1D) is an autoimmune disease characterized by the selective destruction of pancreatic β-cells by autoreactive T-cells. Genome-wide association studies (GWAS) have identified over 150 regions that influence the risk of developing T1D, but genetics alone cannot account for the increasing incidence of T1D. Various environmental factors have been examined to identify their potential contributions, however, no report has demonstrated a direct role of these environmental factors in T1D onset. In the nonobese diabetic (NOD) mouse model of T1D, over 90% of the anti-insulin CD4+ T-cell clones target amino acids 9-23 of the insulin B chain (insB:9-23). More importantly, insB:9-23 specific T-cells have been identified in islets obtained from human organ donors with T1D as well as peripheral blood lymphocytes of living T1D patients. In this study, focusing on the main insulin epitope, insB:9-23, we explored whether a microbial insB:9-23 mimic could modulate T1D. We demonstrate that a microbial insB:9-23 mimic of Parabacteroides distasonis, a human gut commensal, exclusively stimulates NOD mouse T-cells specific to insB:9-23. Indeed, immunization of NOD mice with either the bacterial mimic peptide or insB:9-23 further verified the cross-reactivity in vivo. P. distasonis colonization of the female NOD mice gut accelerated T1D onset. In addition, adoptive transfer of splenocytes from NOD mice colonized with P. distasonis to NOD.SCID recipients conferred the enhanced disease phenotype. Integration analysis of published DIABIMMUNE T1D gut microbiome data revealed that P. distasonis is lacking in the gut microbiota of the children below age 1 who will eventually develop T1D in Russia and Estonia. Notably, P. distasonis insB:9-23 mimic can stimulate human T-cell clones specific to insB:9-23. Taken together, our studies define a potential molecular mimicry link between T1D pathogenesis and the gut microbiota. Disclosure K. Girdhar: None. E. Altindis: None. Q. Huang: None. I. Chow: None. C. Brady: None. A. Raisingani: None. T. Tran: None. W. Kwok: None. M. A. Atkinson: None. C. Kahn: Advisory Panel; Self; ERX Pharmaceuticals, Kaleido Biosciences, Inc., Consultant; Self; Flagship Pioneering, Sana/Cobalt. Funding National Institutes of Health (1K01DK117967-01, R01DK031026, R01DK033201, P01AI042288); G. Harold & Leila Y. Mathers Foundation; Iacocca Family Foundation

Single-cell RNA Sequencing Reveals Sexually Dimorphic Transcriptome and Type 2 Diabetes Genes in Mouse Islet β Cells

Type 2 diabetes (T2D) is characterized by the malfunction of pancreatic β cells. Susceptibility and pathogenesis of T2D can be affected by multiple factors, including sex differences. However, the mechanisms underlying sex differences in T2D susceptibility and pathogenesis remain unclear. Using single-cell RNA sequencing (scRNA-seq), we demonstrate the presence of sexually dimorphic transcriptomes in mouse β cells. Using a high-fat diet-induced T2D mouse model, we identified sex-dependent T2D altered genes, suggesting sex-based differences in the pathological mechanisms of T2D. Furthermore, based on islet transplantation experiments, we found that compared to mice with sex-matched islet transplants, sex-mismatched islet transplants in healthy mice showed down-regulation of genes involved in the longevity regulating pathway of β cells. Moreover, the diabetic mice with sex-mismatched islet transplants showed impaired glucose tolerance. These data suggest sexual dimorphism in T2D pathogenicity, indicating that sex should be considered when treating T2D. We hope that our findings could provide new insights for the development of precision medicine in T2D.

Glucagon Receptor Antagonism-Mediated β-Cell Regeneration as an Effective Anti-Diabetic Therapy

Type 1 Diabetes (T1D) is a chronic disease with potentially severe complications, and β-cell deficiency underlies this disease. Despite active research, no therapy to date has been able to induce β-cell regeneration in humans. Here, we discovered the β-cell regenerative effects of glucagon receptor antibodies (anti-GcgR). Treatment with anti-GcgR in mouse models of β-cell deficiency leads to reversal of hyperglycemia, increased plasma insulin and C-peptide levels, and restored β-cell mass. We demonstrate that both β-cell proliferation and α- to β-cell transdifferentiation contribute to anti-GcgR-induced β-cell regeneration. Interestingly, anti-GcgR-induced α-cell hyperplasia can be uncoupled from β-cell regeneration with treatment cessation and antibody elimination from the body. Importantly, we are able to show that anti-GcgR induced α- to β-cell transdifferentiation is also observed in non-human primates. Furthermore, anti-GcgR and anti-CD3 combination therapy reverses diabetes and increases β-cell mass in the non-obese diabetic (NOD) mouse model of T1D. Taken together, our novel findings suggest that the combination of anti-GcgR with an immune modulator may be an effective therapy for T1D.

Study of the relevance of the ob/ob mouse as a diabetic cardiomyopathy model

The prevalence of type 2 diabetes (T2D) is increasing dramatically in our modern world. Cardiovascular complications are the leading cause of T2D-related morbi-mortality, notably diabetic cardiomyopathy (DCM). This cardiac dysfunction is characterized by hypertrophy and diastolic dysfunction. DCM animal models are required to better define the underlying mechanisms. We aim to characterize the cardiac and contractile function of the leptin-deficient ob/ob mouse as a potential DCM model. Twelve weeks-old ob/ob mice were characterized at the metabolic level. Contractile function was evaluated by echocardiography while Ca 2+ transients were measured by imaging. Ob/ob mice displayed increased body weight, hyperglycemia and cardiac insulin resistance. Despite a slight thickening of the posterior left ventricular wall, the heart of ob/ob mice does not exhibit any cardiac hypertrophy, further validated by no change in the cardiomyocyte membrane capacitance measured by electrophysiology. Echocardiography revealed no diastolic dysfunction in the ob/ob mice but a mild strain rate reduction with preserved ejection fraction. Peak amplitudes of Ca 2+ transients were unchanged but time to peak was decreased in the ob/ob cardiomyocyte. Histological analysis showed triglyceride accumulation in the ob/ob heart. Our data demonstrate that the 12 weeks-old ob/ob mice, well characterized as a T2D and obese mouse model, do not recapitulate the main hallmarks of DCM, i.e. diastolic dysfunction and cardiac hypertrophy. The high accumulation of triglycerides and the subsequent lipotoxicity in the ob/ob cardiomyocytes may rather rely on their obese phenotype than their diabetic one, probably contributing to the early systolic dysfunction.

Myocardial ischemia-reperfusion and diabetes: The crux of animal model choice

Due to the failure of the translation of cardioprotective drugs against myocardial infarction from bench to bedside, revising animal models has become a necessity. Owing to its current growing incidence, type 2 diabetes (T2D) represents one of the main risk factors of co-morbidities in myocardial infarction, yet discrepancies exist between reported animal and human studies. We aimed to compare the impact of diabetes on infarct size after cardiac ischemia-reperfusion in a human cohort of ST elevation myocardial infarction (STEMI) patients with a diet-induced mouse model of T2D, using a high-fat high-sucrose diet for 16 weeks (HFHSD). Infarct size was evaluated by MRI in a cohort of 250 STEMI patients after primary percutaneous intervention. For mouse study, T2D was induced by 16 weeks of HFHSD versus a standard diet (SD) then in vivo 45 mins ischemia followed by 24 hrs of reperfusion were performed to compare myocardial infarct size. To mimic the diabetic medication regimen, 6 weeks of oral gavage with Metformin was performed in the HFHSD group: cell death upon in vitro 70 min hypoxia-2 h reoxygenation (H/R) on isolated cardiomyocytes was analysed by propidium-iodide staining. A small fraction (< 14%) of STEMI patients were diabetic and did not show a bigger infarct size when compared to non-diabetic ones. HFHSD mice had bigger infarct size compared to SD (HFHSD 47.8 [43.5, 49.0] vs. SD 37.3 [33.5, 43.6] %, n = 8–9/group, P < 0.05). Metformin treatment reduced cell death after H/R in the HFHSD cardiomyocytes, to a similar extent as in SD cells. Our data highlight that anti-diabetic medications may have a protective effect, thus they should be included in the pre-clinical studies of cardioprotective approaches in diabetic models. However, the relatively low number of diabetic patients in the STEMI population should also lead us to think about the inclusion of other risk factors in our animal models, notably aging.

Myocardial Ischemia-Reperfusion and Diabetes: Lessons Learned From Bedside to Bench.

In front of the failure to translate from bench to bedside cardioprotective drugs against myocardial ischemia-reperfusion, research scientists are currently revising their animal models. Owing to its growing incidence nowadays, type 2 diabetes (T2D) represents one of the main risk factors of co-morbidities in myocardial infarction. However, discrepancies exist between reported animal and human studies. Our aim was here to compare the impact of diabetes on cell death after cardiac ischemia-reperfusion in a human cohort of ST-elevation myocardial infarction (STEMI) patients with a diet-induced mouse model of T2D, using a high-fat high-sucrose diet for 16 weeks (HFHSD). Interestingly, a small fraction (<14%) of patients undergoing a myocardial infarct were diabetic, but treated, and did not show a bigger infarct size when compared to non-diabetic patients. On the contrary, HFHSD mice displayed an increased infarct size after an in vivo cardiac ischemia-reperfusion, together with an increased cell death after an in vitro hypoxia-reoxygenation on isolated cardiomyocytes. To mimic the diabetic patients' medication profile, 6 weeks of oral gavage with Metformin was performed in the HFHSD mouse group. Metformin treatment of the HFHSD mice led to a similar extent of lower cell death after hypoxia-reoxygenation as in the standard diet group, compared to the HFHSD cardiomyocytes. Altogether, our data highlight that due to their potential protective effect, anti-diabetic medications should be included in pre-clinical study of cardioprotective approaches. Moreover, since diabetic patients represent only a minor fraction of the STEMI patients, diabetic animal models may not be the most suitable translatable model to humans, unlike aging that appears as a common feature of all infarcted patients.

Gastrointestinal Helminth Infection Improves Insulin Sensitivity, Decreases Systemic Inflammation, and Alters the Composition of Gut Microbiota in Distinct Mouse Models of Type 2 Diabetes.

Type 2 diabetes (T2D) is a major health problem and is considered one of the top 10 diseases leading to death globally. T2D has been widely associated with systemic and local inflammatory responses and with alterations in the gut microbiota. Microorganisms, including parasitic worms and gut microbes have exquisitely co-evolved with their hosts to establish an immunological interaction that is essential for the formation and maintenance of a balanced immune system, including suppression of excessive inflammation. Herein we show that both prophylactic and therapeutic infection of mice with the parasitic hookworm-like nematode, Nippostrongylus brasiliensis, significantly reduced fasting blood glucose, oral glucose tolerance and body weight gain in two different diet-induced mouse models of T2D. Helminth infection was associated with elevated type 2 immune responses including increased eosinophil numbers in the mesenteric lymph nodes, liver and adipose tissues, as well as increased expression of IL-4 and alternatively activated macrophage marker genes in adipose tissue, liver and gut. N. brasiliensis infection was also associated with significant compositional changes in the gut microbiota at both the phylum and order levels. Our findings show that N. brasiliensis infection drives changes in local and systemic immune cell populations, and that these changes are associated with a reduction in systemic and local inflammation and compositional changes in the gut microbiota which cumulatively might be responsible for the improved insulin sensitivity observed in infected mice. Our findings indicate that carefully controlled therapeutic hookworm infection in humans could be a novel approach for treating metabolic syndrome and thereby preventing T2D.

Characterization of Mechanical Allodynia and Skin Innervation in a Mouse Model of Type-2 Diabetes Induced by Cafeteria-Style Diet and Low-Doses of Streptozotocin.

Background: Painful distal symmetrical polyneuropathy (DPN) is a frequent complication of type-2 diabetes mellitus (T2DM) that commonly presents as neuropathic pain and loss of skin nerve fibers. However, there are limited therapies to effectively treat DPN and many of the current animal models of T2DM-induced DPN do not appear to mirror the human disease. Thus, we validated a DPN mouse model induced by a cafeteria-style diet plus low-doses of streptozotocin (STZ). Methods: Female C57BL/6J mice were fed either standard (STD) diet or obesogenic cafeteria (CAF) diet for 32 weeks, starting at 8 weeks old. Eight weeks after starting diets, CAF or STD mice received either four low-doses of STZ or vehicle. Changes in body weight, blood glucose and insulin levels, as well as oral glucose- and insulin-tolerance tests (OGTT and ITT) were determined. The development of mechanical hypersensitivity of the hindpaws was determined using von Frey filaments. Moreover, the effect of the most common neuropathic pain drugs was evaluated on T2DM-induced mechanical allodynia. Finally, the density of PGP -9.5+ (a pan-neuronal marker) axons in the epidermis from the hindpaw glabrous skin was quantified. Results: At 22–24 weeks after STZ injections, CAF + STZ mice had significantly higher glucose and insulin levels compared to CAF + VEH, STD + STZ, and STD + VEH mice, and developed glucose tolerance and insulin resistance. Skin mechanical sensitivity was detected as early as 12 weeks post-STZ injections and it was significantly attenuated by intraperitoneal acute treatment with amitriptyline, gabapentin, tramadol, duloxetine, or carbamazepine but not by diclofenac. The density of PGP-9.5+ nerve fibers was reduced in CAF + STZ mice compared to other groups. Conclusion: This reverse translational study provides a painful DPN mouse model which may help in developing a better understanding of the factors that generate and maintain neuropathic pain and denervation of skin under T2DM and to identify mechanism-based new treatments.

Soluble Antigen Arrays Efficiently Deliver Peptides and Arrest Spontaneous Autoimmune Diabetes.

Antigen-specific immunotherapy (ASIT) offers a targeted treatment of autoimmune diseases that selectively inhibits autoreactive lymphocytes, but there remains an unmet need for approaches that address the limited clinical efficacy of ASIT. Soluble antigen arrays (SAgAs) deliver antigenic peptides or proteins in multivalent form, attached to a hyaluronic acid backbone using either hydrolysable linkers (hSAgAs) or stable click chemistry linkers (cSAgAs). They were evaluated for the ability to block spontaneous development of disease in a nonobese diabetic mouse model of type 1 diabetes (T1D). Two peptides, a hybrid insulin peptide and a mimotope, efficiently prevented the onset of T1D when delivered in combination as SAgAs, but not individually. Relative to free peptides administered at equimolar dose, SAgAs (particularly cSAgAs) enabled a more effective engagement of antigen-specific T cells with greater persistence and induction of tolerance markers, such as CD73, interleukin-10, programmed death-1, and KLRG-1. Anaphylaxis caused by free peptides was attenuated using hSAgA and obviated using cSAgA platforms. Despite similarities, the two peptides elicited largely nonoverlapping and possibly complementary responses among endogenous T cells in treated mice. Thus, SAgAs offer a novel and promising ASIT platform superior to free peptides in inducing tolerance while mitigating risks of anaphylaxis for the treatment of T1D.

Exercise Improves Endothelial Function Associated with Alleviated Inflammation and Oxidative Stress of Perivascular Adipose Tissue in Type 2 Diabetic Mice.

Perivascular adipose tissue (PVAT), a type of adipose tissue that surrounds the blood vessels, has been considered an active component of the blood vessel walls and involved in vascular homeostasis. Recent evidence shows that increased inflammation and oxidative stress in PVAT contribute to endothelial dysfunction in type 2 diabetes (T2D). Exercise is an important nonpharmacological approach for vascular diseases. However, there is limited information regarding whether the beneficial effects of exercise on vascular function is related to the PVAT status. In this study, we investigated whether exercise can decrease oxidative stress and inflammation of PVAT and promote the improvement of endothelial function in a T2D mouse model. Diabetic db/db (5-week old) mice performed treadmill exercise (10 m/min) or keep sedentary for 8 weeks. Body weight, fasting blood glucose levels, glucose, and insulin tolerance were determined. The cytokines (IL-6, IL-10, IFN-γ, and TNF-a) and adiponectin levels, macrophage polarization and adipocyte type in PVAT, oxidative stress, and nitric oxide (NO) expression in the vascular wall were evaluated. The adhesion ability of primary aorta endothelial cells was analyzed. Our data showed that (1) diabetic db/db mice had increased body weight and fasting blood glucose level, compromised glucose tolerance, and insulin sensitivity, which were decreased/improved by exercise intervention. (2) Exercise intervention increased the percentage of multilocular brown adipocytes, promoted M1 to M2 macrophage polarization, associating with an increase of adiponectin and IL-10 levels and decrease of IFN-γ, IL-6, and TNF-a levels in PVAT. (3) Exercise decreased superoxide production in PVAT and the vascular wall of diabetic mice, accompanied with increased NO level. (4) The adhesion ability of aorta endothelial cells to leukocytes was decreased in exercised db/db mice, accompanied by decreased intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) expressions. Of interesting, coculture with PVAT-culture medium from exercised db/db mice could also reduce ICAM-1 and VCAM-1 expressions in primary endothelial cells. In conclusion, our data suggest that exercise improved endothelial function by attenuating the inflammation and oxidative stress in PVAT.

3D quantification of changes in pancreatic islets in mouse models of diabetes type I and II.

ABSTRACTDiabetes is characterized by rising levels of blood glucose and is often associated with a progressive loss of insulin-producing beta cells. Recent studies have demonstrated that it is possible to regenerate new beta cells through proliferation of existing beta cells or trans-differentiation of other cell types into beta cells, raising hope that diabetes can be cured through restoration of functional beta cell mass. Efficient quantification of beta cell mass and islet characteristics is needed to enhance drug discovery for diabetes. Here, we report a 3D quantitative imaging platform for unbiased evaluation of changes in islets in mouse models of type I and II diabetes. To determine whether the method can detect pharmacologically induced changes in beta cell volume, mice were treated for 14 days with either vehicle or the insulin receptor antagonist S961 (2.4 nmol/day) using osmotic minipumps. Mice treated with S961 displayed increased blood glucose and insulin levels. Light-sheet imaging of insulin and Ki67 (also known as Mki67)-immunostained pancreata revealed a 43% increase in beta cell volume and 21% increase in islet number. S961 treatment resulted in an increase in islets positive for the cell proliferation marker Ki67, suggesting that proliferation of existing beta cells underlies the expansion of total beta cell volume. Using light-sheet imaging of a non-obese diabetic mouse model of type I diabetes, we also characterized the infiltration of CD45 (also known as PTPRC)-labeled leukocytes in islets. At 14 weeks, 40% of the small islets, but more than 80% of large islets, showed leukocyte infiltration. These results demonstrate how quantitative light-sheet imaging can capture changes in individual islets to help pharmacological research in diabetes.

Differential Effects of Empagliflozin on Microvascular Complications in Murine Models of Type 1 and Type 2 Diabetes.

Simple SummaryType 1 and type 2 diabetes can lead to serious health problems that affect many organs including the nerve, the eye, and the kidney. These health problems can be disabling or even life-threatening, and to date, there are no effective therapies that can slow or prevent their development. We studied the effect of empagliflozin, a medication that reduces blood sugar levels and the risk of cardiovascular disease, on the nerve, eye, and kidney in a side-by-side comparison of type 1 and type 2 mouse models. Empagliflozin had no beneficial effects on disease progression in type 2 diabetic mice, but improved nerve function in the type 1 diabetic model, an effect that was accompanied by reduced markers of oxidative injury. These findings support the concept that different mechanisms contribute to nerve damage in type 1 and type 2 diabetes. Our results further support our view that the concept of one therapy will benefit all complications should be abandoned as we pursue more personalized, tissue-specific, diabetes type-specific treatments.Microvascular complications account for the significant morbidity associated with diabetes. Despite tight glycemic control, disease risk remains especially in type 2 diabetes (T2D) patients and no therapy fully prevents nerve, retinal, or renal damage in type 1 diabetes (T1D) or T2D. Therefore, new antidiabetic drug classes are being evaluated for the treatment of microvascular complications. We investigated the effect of empagliflozin (EMPA), an inhibitor of the sodium/glucose cotransporter 2 (SGLT2), on diabetic neuropathy (DPN), retinopathy (DR), and kidney disease (DKD) in streptozotocin-induced T1D and db/db T2D mouse models. EMPA lowered blood glycemia in T1D and T2D models. However, it did not ameliorate any microvascular complications in the T2D model, which was unexpected, given the protective effect of SGLT2 inhibitors on DKD progression in T2D subjects. Although EMPA did not improve DKD in the T1D model, it had a potential modest effect on DR measures and favorably impacted DPN as well as systemic oxidative stress. These results support the concept that glucose-centric treatments are more effective for DPN in T1D versus T2D. This is the first study that provides an evaluation of EMPA treatment on all microvascular complications in a side-by-side comparison in T1D and T2D models.

T Cells from NOD-PerIg Mice Target Both Pancreatic and Neuronal Tissue.

It has become increasingly appreciated that autoimmune responses against neuronal components play an important role in type 1 diabetes (T1D) pathogenesis. In fact, a large proportion of islet-infiltrating B lymphocytes in the NOD mouse model of T1D produce Abs directed against the neuronal type III intermediate filament protein peripherin. NOD-PerIg mice are a previously developed BCR-transgenic model in which virtually all B lymphocytes express the H and L chain Ig molecules from the intra-islet-derived anti-peripherin-reactive hybridoma H280. NOD-PerIg mice have accelerated T1D development, and PerIg B lymphocytes actively proliferate within islets and expand cognitively interactive pathogenic T cells from a pool of naive precursors. We now report adoptively transferred T cells or whole splenocytes from NOD-PerIg mice expectedly induce T1D in NOD.scid recipients but, depending on the kinetics of disease development, can also elicit a peripheral neuritis (with secondary myositis). This neuritis was predominantly composed of CD4+ and CD8+ T cells. Ab depletion studies showed neuritis still developed in the absence of NOD-PerIg CD8+ T cells but required CD4+ T cells. Surprisingly, sciatic nerve-infiltrating CD4+ cells had an expansion of IFN-γ- and TNF-α- double-negative cells compared with those within both islets and spleen. Nerve and islet-infiltrating CD4+ T cells also differed by expression patterns of CD95, PD-1, and Tim-3. Further studies found transitory early B lymphocyte depletion delayed T1D onset in a portion of NOD-PerIg mice, allowing them to survive long enough to develop neuritis outside of the transfer setting. Together, this study presents a new model of peripherin-reactive B lymphocyte-dependent autoimmune neuritis.

Exposure to Static Magnetic and Electric Fields Treats Type 2 Diabetes

Aberrant redox signaling underlies the pathophysiology of many chronic metabolic diseases, including type 2 diabetes (T2D). Methodologies aimed at rebalancing systemic redox homeostasis have had limited success. A noninvasive, sustained approach would enable the long-term control of redox signaling for the treatment of T2D. We report that static magnetic and electric fields (sBE) noninvasively modulate the systemic GSH-to-GSSG redox couple to promote a healthier systemic redox environment that is reducing. Strikingly, when applied to mouse models of T2D, sBE rapidly ameliorates insulin resistance and glucose intolerance in as few as 3days with no observed adverse effects. Scavenging paramagnetic byproducts of oxygen metabolism with SOD2 in hepatic mitochondria fully abolishes these insulin sensitizing effects, demonstrating that mitochondrial superoxide mediates induction of these therapeutic changes. Our findings introduce a remarkable redox-modulating phenomenon that exploits endogenous electromagneto-receptive mechanisms for the noninvasive treatment of T2D, and potentially other redox-related diseases.