Set it and forget it: Engineered cells for drug delivery.

Type 2 diabetes mellitus (T2DM) is a chronic and progressive hyperglycemic condition. Glucagon-like peptide-1 (GLP1) is an incretin secreted from pancreatic β-cells and helps to produce insulin to balance the blood glucose level without the risk of hypoglycemia. However, the therapeutic application of GLP1 is limited by its intrinsic short half-life and rapid metabolic clearance in the body. To enhance the antidiabetic effect of GLP1, we designed a human cysteine-modified IgG1-Fc antibody-mediated oral gene delivery vehicle, which helps to produce GLP1 sustainably in the target site with the help of increased half-life of the Fc-conjugated nanocarrier, protects GLP1 from acidic and enzymatic degradation in the gastrointestinal (GI) tract, uptakes and transports the GLP1 formulation through the neonatal Fc receptor (FcRn), and helps to release the GLP1 gene in the intestine. Our formulation could reduce the blood glucose from about an average of 320 mg/dL (hyperglycemic) to 150 mg/dL (normal blood glucose concentration) in diabetic mice, which is about 50% reduction of the total blood glucose concentration. GLP1 (500 μg) complexed with the IgG1-Fc carrier was proven to be the optimal dose for a complete reduction of hyperglycemic conditions in diabetic mice. A significant amount of insulin production and the presence of GLP1 peptide were observed in the pancreatic islets of oral GLP1 formulation-treated diabetic mice in immunohistochemistry analysis compared to nontreated diabetic mice. The orally given formulation was completely nontoxic according to the histopathology analysis of mice organ tissues, and no mice death was observed. Our antibody-mediated oral gene delivery system is a promising tool for various oral therapeutic gene delivery applications to treat diseases like diabetes.

To develop an oral delivery system of glucagon-like peptide 1 (GLP-1) (28-36) for treating type-2 diabetes, B.S-GLP-1(28-36), a recombinant Bacillus subtilis spores transformed with a plasmid vector encoding five consecutive GLP-1 (28-36) nonapeptides with an enterokinase site was constructed. GLP-1(28-36) nonapeptide was successfully expressed on the surface of B. subtilis spores and validated by Western blot and immunofluorescence. The therapeutic effect of oral administration of B.S-GLP-1(28-36) spores was evaluated in type 2 diabetic model mice. The efficacy of recombinant spores was examined for a period of 13weeks after oral administration in diabetic mice. At the end of the sixth week, diabetic mice with oral administration of BS-GLP-1(28-36) spores showed decreased blood glucose levels from 2·4×10- 2 moll-1 to 1·7×10- 2 moll-1 . By the ninth week, the mean fasting blood glucose level in the experimental group was significantly lower than that in the control group 30min after injection of pyruvate. At the end of the 10th week of oral administration, the blood glucose of the experimental group was significantly lower than that of the control group after intraperitoneal injection of glucose. By the 12th week, fasting blood glucose level and fasting insulin level were measured in all mice, the results showed that the recombinant spores increased the insulin sensitivity of mice. The results of pathological observation showed that the recombinant spores also had a certain protective effect on the liver and islets of mice, and the content of GLP-1(28-36) in the pancreas of the experimental group was increased. The results of this study revealed that GLP-1(28-36) nonapeptides can reduce blood glucose and play an important role in the treatment of type 2 diabetes.

Elevated glucagon-like peptide-1 plasma levels, as a possible adaptive response, in diabetic NOD mice

AimSeveral recent reports have revealed that dipeptidyl peptidase (DPP)-4 inhibitors have suppressive effects on atherosclerosis in apolipoprotein E-null (Apoe−/−) mice. It remains to be seen, however, whether this effect stems from increased levels of the two active incretins, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP).MethodsNontreated Apoe−/− mice, streptozotocin-induced diabetic Apoe−/− mice, and db/db diabetic mice were administered the DPP-4 inhibitor vildagliptin in drinking water and co-infused with either saline, the GLP-1 receptor blocker, exendin(9–39), the GIP receptor blocker, (Pro3)GIP, or both via osmotic minipumps for 4 weeks. Aortic atherosclerosis and oxidized low-density lipoprotein-induced foam cell formation in exudate peritoneal macrophages were determined.ResultsVildagliptin increased plasma GLP-1 and GIP levels without affecting food intake, body weight, blood pressure, or plasma lipid profile in any of the animals tested, though it reduced HbA1c in the diabetic mice. Diabetic Apoe−/− mice exhibited further-progressed atherosclerotic lesions and foam cell formation compared with nondiabetic counterparts. Nondiabetic and diabetic Apoe−/− mice showed a comparable response to vildagliptin, namely, remarkable suppression of atherosclerotic lesions with macrophage accumulation and foam cell formation in peritoneal macrophages. Exendin(9–39) or (Pro3)GIP partially attenuated the vildagliptin-induced suppression of atherosclerosis. The two blockers in combination abolished the anti-atherosclerotic effect of vildagliptin in nondiabetic mice but only partly attenuated it in diabetic mice. Vildagliptin suppressed macrophage foam cell formation in nondiabetic and diabetic mice, and this suppressive effect was abolished by infusions with exendin(9–39)+(Pro3)GIP. Incubation of DPP-4 or vildagliptin in vitro had no effect on macrophage foam cell formation.ConclusionsVildagliptin confers a substantial anti-atherosclerotic effect in both nondiabetic and diabetic mice, mainly via the action of the two incretins. However, the partial attenuation of atherosclerotic lesions by the dual incretin receptor antagonists in diabetic mice implies that vildagliptin confers a partial anti-atherogenic effect beyond that from the incretins.

PurposeMyocardia in diabetic patients exhibit increased vulnerability after ischemia/reperfusion injury (IRI). It has been demonstrated that glucagon-like peptide-1 (GLP-1) has a protective effect on cardiomyocytes. Protein kinase C (PKC) acts as a key regulator of many signaling pathways including oxidative stress and apoptosis. Our hypothesis is that increased vulnerability of myocardia in diabetic patients is partly due to GLP-1 resistance. The aim of this study was to explore the role of PKC in GLP-1 resistance in diabetic cardiomyocytes.MethodsCardiac function of diabetic or non-diabetic mice after myocardial IRI was detected with or without administration of GLP-1 analog exendin-4. Impacts of diabetes mellitus on GLP-1R expression in myocardia after IRI were accessed by Western blot. By transfecting PKC isoforms siRNA, in vitro study helped to identify the exact PKC isoforms which contributed to the downregulatio n of GLP-1R or impaired post-receptor signaling pathways in rodent cardiomyocytes (H9C2 cells) cultured by high glucose.ResultsThe cardioprotective effects of endogenous GLP-1 were impaired in diabetic mice after myocardial IRI and administration of exendin-4 had no significant effects in restoring cardiac function. GLP-1 receptor (GLP-1R) expression decreased in H9C2 cells cultured by high glucose and knockdown of PKCβ partly restored GLP-1R expression. Overexpression of PKCδ induced by high glucose in H9C2 cells impaired GLP-1 post-receptor anti-apoptotic signaling pathways by inhibition of Akt phosphorylation. Knockdown of both PKCβ and PKCδ significantly restored cardioprotective effects of GLP-1 in H9C2 cells cultured by high glucose.ConclusionOur study found out a new mechanism of GLP-1 resistance that high glucose-induced overexpression of PKCβ and PKCδ impaired cardioprotective effects of GLP-1 by downregulation of GLP-1R and inhibition of GLP-1 post-receptor anti-apoptotic signaling pathways, thus provided a new perspective in treating myocardial IRI in diabetic patients.

OBJECTIVE—Glucagon-like peptide-1 (GLP-1) and gastrin promote pancreatic β-cell function, survival, and growth. Here, we investigated whether GLP-1 and gastrin can restore the β-cell mass and reverse hyperglycemia in NOD mice with autoimmune diabetes.RESEARCH DESIGN AND METHODS—Acutely diabetic NOD mice were treated with GLP-1 and gastrin, separately or together, twice daily for 3 weeks. Blood glucose was measured weekly and for a further 5 weeks after treatments, after which pancreatic insulin content and β-cell mass, proliferation, neogenesis, and apoptosis were measured. Insulin autoantibodies were measured, and adoptive transfer of diabetes and syngeneic islet transplant studies were done to evaluate the effects of GLP-1 and gastrin treatment on autoimmunity.RESULTS—Combination therapy with GLP-1 and gastrin, but not with GLP-1 or gastrin alone, restored normoglycemia in diabetic NOD mice. The GLP-1 and gastrin combination increased pancreatic insulin content, β-cell mass, and insulin-positive cells in pancreatic ducts, and β-cell apoptosis was decreased. Insulin autoantibodies were reduced in GLP-1–and gastrin-treated NOD mice, and splenocytes from these mice delayed adoptive transfer of diabetes in NOD-scid mice. Syngeneic islet grafts in GLP-1–and gastrin-treated NOD mice were infiltrated by leukocytes with a shift in cytokine expression from interferon-γ to transforming growth factor-β1, and β-cells were protected from apoptosis.CONCLUSIONS—Combination therapy with GLP-1 and gastrin restores normoglycemia in diabetic NOD mice by increasing the pancreatic β-cell mass and downregulating the autoimmune response.

Sodium–glucose cotransporter 2 inhibitors, efficacious antidiabetic agents that have cardiovascular and renal benefits, can promote pancreatic β-cell regeneration in type 2 diabetic mice. However, the underlying mechanism remains unclear. In this study, we aimed to use multiomics to identify the mediators involved in β-cell regeneration induced by dapagliflozin. We showed that dapagliflozin lowered blood glucose level, upregulated plasma insulin level, and increased islet area in db/db mice. Dapagliflozin reshaped gut microbiota and modulated microbiotic and plasmatic metabolites related to tryptophan metabolism, especially l-tryptophan, in the diabetic mice. Notably, l-tryptophan upregulated the mRNA level of glucagon-like peptide 1 (GLP-1) production–related gene (Gcg and Pcsk1) expression and promoted GLP-1 secretion in cultured mouse intestinal L cells, and it increased the supernatant insulin level in primary human islets, which was eliminated by GPR142 antagonist. Transplant of fecal microbiota from dapagliflozin-treated mice, supplementation of l-tryptophan, or treatment with dapagliflozin upregulated l-tryptophan, GLP-1, and insulin or C-peptide levels and promoted β-cell regeneration in db/db mice. Addition of exendin 9-39, a GLP-1 receptor (GLP-1R) antagonist, or pancreatic Glp1r knockout diminished these beneficial effects. In summary, treatment with dapagliflozin in type 2 diabetic mice promotes β-cell regeneration by upregulating GLP-1 production, which is mediated via gut microbiota and tryptophan metabolism.Article HighlightsSodium–glucose cotransporter 2 inhibitors, novel and efficacious antidiabetic agents, can preserve β-cell mass in type 2 diabetic animals, but the mechanism remains unclear.We find that dapagliflozin reshapes gut microbiota, improves microbiotic and plasmatic metabolites related to tryptophan metabolism, and increases glucagon-like peptide 1 (GLP-1) production mediated via tryptophan metabolism. GLP-1−GLP-1 receptor signaling participates in the dapagliflozin-induced β-cell regeneration.Our study reveals that the gut microbiota–tryptophan metabolism–GLP-1 axis is a novel mechanism of β-cell regeneration induced by dapagliflozin and provides experimental evidence for its β-cell protection in treating type 2 diabetes.

Dietary supplementation of rutin and rutin-rich buckwheat elevates endogenous glucagon-like peptide 1 levels to facilitate glycemic control in type 2 diabetic mice

Introduction and Objective: GLP-1(32-36), a major end-product of glucagon-like peptide 1 (GLP-1), improves diabetic limb ischemia in mice independent of its insulinotropic effect. However, the mechanisms underlying this effect and its relevance in human ischemic lesions remain unclear. Methods: We used single-cell transcriptomics on the plantar muscles of diabetic foot patients and healthy controls to investigate changes in lipid metabolism genes and pathways. We also applied cellular and spatial metabolomics to evaluate the impact of GLP-1(32-36) on lipid metabolism and lipid accumulation in the gastrocnemius microvasculature in diabetic mice. Adenovirus and lentivirus were used for gene silencing in vivo and in vitro, respectively. Cross orthogonal coupling was employed for drug modification of GLP-1(32-36). Results: High glucose induces lipid metabolism dysregulation in endothelial cells (ECs) and in diabetic mice with limb ischemia. GLP-1(32-36) binds atrial natriuretic peptide receptor A (NPRA) to regulate cholesterol transport via oxysterol-binding protein (OSBP), promoting blood flow in ischemic limbs. NPRA knockdown inhibited GLP-1(32-36)’s pro-angiogenic effects, independent of the GLP-1 receptor (GLP-1R). Single-cell RNA sequencing (scRNA seq) revealed lipid metabolism dysregulation in capillary ECs of diabetic foot patients. To prolong GLP-1(32-36)’s half-life, we synthesized the ROS-responsive prodrug tEC-cRGD-(32-36) for EC-specific delivery, enhancing blood flow recovery and reducing lipid droplet formation. Conclusion: Our findings demonstrate that GLP-1(32-36) regulates lipid metabolism via the NPRA-OSBP axis to alleviate endothelial dysfunction and promote diabetic ischemic recovery, supporting the development of EC-targeting GLP-1(32-36) for treating diabetic ischemia. Disclosure Y. Zhang: None. S. Wang: None. Q. Zhou: None. C. Zheng: None.

Glycemic control of type 2 diabetic patients with coronavirus disease during hospitalization: a proposal for early insulin therapy.

Effects and molecular mechanisms of the antidiabetic fraction of Acorus calamus L. on GLP-1 expression and secretion in vivo and in vitro

BackgroundEpidemiological data show that Helicobacter pylori (H. pylori) infection is not only the most important risk factor for gastric cancer, but is also associated with poor glycemic control in patients with diabetes. However, the direct causal and functional relationship between H. pylori infection and dysglycemia is unclear.MethodA retrospective cohort study was conducted to examine the association between H. pylori infection and glycemic levels in individuals with Type 2 diabetes. C57BL/6 diabetic mice were infected with H. pylori, and the resulting changes in colonic inflammation and intestinal Glucagon-like peptide-1 (GLP-1) secretion were thoroughly examined using immunohistochemistry, RNA sequencing, metagenomic sequencing, and targeted metabolomics. The microbial and metabolomics profiles were analyzed and compared in antibiotic-treated mice through fecal transfer experiments.ResultsH. pylori infection aggravated insulin resistance in diabetic individuals and mice. We identified a unique H. pylori-induced epithelial inflammation and reduced intestinal GLP-1 secretion in the colon. H. pylori infection also interrupts the normal microbial composition in the colon, leading to a decrease in SCFA-producing bacteria and a reduction in acetic and propionate acids. Similar changes were observed in antibiotic-treated mice after receiving fecal transplants from H. pylori-infected diabetic mice. In vitro studies revealed that the intestinal flora of H. pylori-positive diabetic mice inhibited proglucagon transcription, cAMP levels, and GLP-1 secretion in colonic endocrine cells, with SCFA supplementation reversing this effect on GLP-1 production. These microbial, metabolic, and GLP-1 alterations were also seen in antibiotic-treated mice after receiving fecal transplants from H. pylori-infected diabetic mice. H. pylori eradication with antibiotics improved glucose metabolism and GLP-1 secretion to levels comparable to uninfected controls.ConclusionOur studies offer evidence that H. pylori infection significantly contributes to the progression of glucose impairment and insulin resistance. Therefore, incorporating H. pylori status into preventive strategies for diabetes should be taken into account. (Chinese Clinical Trial Registry Center, ChiCTR2200063489, Registered 08 September 2022, https://www.chictr.org.cn/showproj.html?proj=178102).Supplementary InformationThe online version contains supplementary material available at 10.1186/s12866-025-04402-9.

We have previously shown that diabetes causes pericyte dysfunction, leading to loss of vascular integrity and vascular cognitive impairment and dementia (VCID). Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs), used in managing type 2 diabetes mellitus, improve the cognitive function of diabetic individuals beyond glycaemic control, yet the mechanism is not fully understood. In the present study, we hypothesise that GLP-1 RAs improve VCID by preventing diabetes-induced pericyte dysfunction. Mice with streptozotocin-induced diabetes and non-diabetic control mice received either saline (NaCl 154 mmol/l) or exendin-4, a GLP-1 RA, through an osmotic pump over 28 days. Vascular integrity was assessed by measuring cerebrovascular neovascularisation indices (vascular density, tortuosity and branching density). Cognitive function was evaluated with Barnes maze and Morris water maze. Human brain microvascular pericytes (HBMPCs), were grown in high glucose (25 mmol/l) and sodium palmitate (200 μmol/l) to mimic diabetic conditions. HBMPCs were treated with/without exendin-4 and assessed for nitrative and oxidative stress, and angiogenic and blood-brain barrier functions. Diabetic mice treated with exendin-4 showed a significant reduction in all cerebral pathological neovascularisation indices and an improved blood-brain barrier (p<0.05). The vascular protective effects were accompanied by significant improvement in the learning and memory functions of diabetic mice compared with control mice (p<0.05). Our results showed that HBMPCs expressed the GLP-1 receptor. Diabetes increased GLP-1 receptor expression and receptor nitration in HBMPCs. Stimulation of HBMPCs with exendin-4 under diabetic conditions decreased diabetes-induced vascular inflammation and oxidative stress, and restored pericyte function (p<0.05). This study provides novel evidence that brain pericytes express the GLP-1 receptor, which is nitrated under diabetic conditions. GLP-1 receptor activation improves brain pericyte function resulting in restoration of vascular integrity and BBB functions in diabetes. Furthermore, the GLP-1 RA exendin-4 alleviates diabetes-induced cognitive impairment in mice. Restoration of pericyte function in diabetes represents a novel therapeutic target for diabetes-induced cerebrovascular microangiopathy and VCID.

Background: Glucagon-Like Peptide-1 (GLP-1) is an incretin hormone with potent plasma glucose lowering actions that is rapidly degraded by the enzyme Dipeptidyl Peptidase-IV to GLP-1(9 –36) amide . GLP-1(9 –36) amide (GLP1dp) has previously been viewed to be biologically inactive. However, our laboratory has demonstrated that GLP1dp inhibits hyperglycemia-induced production of oxidant species and prevents the inactivation of both eNOS and prostacyclin synthase in cells and diabetic animals. We investigated the effects of GLP1dp in two in vivo diabetic murine models of myocardial ischemia-reperfusion (MI-R) injury. Methods: Diabetic (db/db and STZ-diabetic) mice were treated with 2.4 μg/day of GLP1dp via Alzet pump for 7 days and subjected to 45 min of left coronary artery occlusion and 2 hr of R. At 2 hr of R, hearts were excised and evaluated for infarct (INF) size. Results: Diabetic (db/db) and STZ-diabetic mice treated with GLP1dp exhibited a 37% and 33% reduction in myocardial infarct size following MI-R respectively. Additionally, GLP1dp significantly reduced oxidative stress in the myocardium of these mice. Both models of diabetic mice (db/db and STZ-diabetic) exhibited elevated baseline blood glucose (BG) values of 386 ± 25 and 435 ± 15 mg/dl respectively. After 7 days of GLP1dp therapy, db/db mice exhibited a 48% reduction in BG values. In contrast, no reduction in BG was observed in the STZ-diabetic mice. Conclusion : Administration of GLP1dp peptide confers cardioprotection in diabetic mice by attenuating the extent of oxidant-mediated injury following MI-R. The cardioprotective actions of GLP1dp appear to be independent of any effects on blood glucose.

Tissue ischemia promotes vasculogenesis through chemokine-induced recruitment of bone marrow-derived endothelial progenitor cells (EPCs). Diabetes significantly impairs this process. Because hyperglycemia increases reactive oxygen species in a number of cell types, and because many of the defects responsible for impaired vasculogenesis involve HIF1-regulated genes, we hypothesized that HIF1 function is impaired in diabetes because of reactive oxygen species-induced modification of HIF1alpha by the glyoxalase 1 (GLO1) substrate methylglyoxal. Decreasing superoxide in diabetic mice by either transgenic expression of manganese superoxide dismutase or by administration of an superoxide dismutase mimetic corrected post-ischemic defects in neovascularization, oxygen delivery, and chemokine expression, and normalized tissue survival. In hypoxic fibroblasts cultured in high glucose, overexpression of GLO1 prevented reduced expression of both the EPC mobilizing chemokine stromal cell-derived factor-1 (SDF-1) and of vascular epidermal growth factor, which modulates growth and differentiation of recruited EPCs. In hypoxic EPCs cultured in high glucose, overexpression of GLO1 prevented reduced expression of both the SDF-1 receptor CXCR4, and endothelial nitric-oxide synthase, an enzyme essential for EPC mobilization. HIF1alpha modification by methylglyoxal reduced heterodimer formation and HIF1alpha binding to all relevant promoters. These results provide a basis for the rational design of new therapeutics to normalize impaired ischemia-induced vasculogenesis in patients with diabetes.