RESUMO
In the present era of "Diabetic Pandemic", peptide-based therapies have generated immense interest however, are facing odds due to inevitable limitations like stability, delivery complications and off-target effects. One such promising molecule is C-peptide (CPep, 31 amino acid polypeptide with t1/2 30 min); it is a cleaved subunit of pro-insulin, well known to suppress microvascular complications in kidney but has not been able to undergo translation to the clinic till date. Herein, a polymeric CPep nano-complexes (NPX) was prepared by leveraging electrostatic interaction between in-house synthesized cationic, polyethylene carbonate (PEC) based copolymer (Mol. wt. 44,767 Da) and negatively charged CPep (Mol. wt. 3299 Da) at pH 7.4 and further evaluated in vitro and in vivo. NPX exhibited a spherical morphology with a particle size of 167 nm and zeta potential equivalent to +10.3, with 85.70 % of CPep complexation efficiency. The cellular uptake of FITC-tagged CPep NPX was 95.61 % in normal rat kidney cells, NRK-52E. Additionally, the hemocompatible NPX showed prominent cell-proliferative, anti-oxidative (1.8 folds increased GSH; 2.8 folds reduced nitrite concentration) and anti-inflammatory activity in metabolic stress induced NRK-52E cells as well. The observation was further confirmed by upregulation of anti-apoptotic protein BCl2 by 3.5 folds, and proliferative markers (ß1-integrin and EGFR) by 3.5 and 2.3 folds, respectively, compared to the high glucose treated control group. Pharmacokinetic study of NPX in Wistar rats revealed a 6.34 folds greater half-life than free CPep. In in-vivo efficacy study in STZ-induced diabetic nephropathy animal model, NPX reduced blood glucose levels and IL-6 levels significantly by 1.3 and 2.5 folds, respectively, as compared to the disease control group. The above findings suggested that NPX has tremendous potential to impart sustained release of CPep, resulting in enhanced efficacy to treat diabetes-induced nephropathy and significantly improved renal pathology.
Assuntos
Anti-Inflamatórios , Apoptose , Peptídeo C , Nefropatias Diabéticas , Nanosferas , Animais , Ratos , Nefropatias Diabéticas/tratamento farmacológico , Nefropatias Diabéticas/patologia , Nefropatias Diabéticas/metabolismo , Apoptose/efeitos dos fármacos , Nanosferas/química , Peptídeo C/farmacologia , Peptídeo C/metabolismo , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/química , Linhagem Celular , Diabetes Mellitus Experimental/tratamento farmacológico , Eletricidade Estática , MasculinoRESUMO
Proinsulin C-peptide, a biologically active polypeptide released from pancreatic ß-cells, is known to prevent hyperglycemia-induced microvascular leakage; however, the role of C-peptide in migration and invasion of cancer cells is unknown. Here, we investigated high glucose-induced migration and invasion of ovarian cancer cells and the inhibitory effects of human C-peptide on metastatic cellular responses. In SKOV3 human ovarian cancer cells, high glucose conditions activated a vicious cycle of reactive oxygen species (ROS) generation and transglutaminase 2 (TGase2) activation through elevation of intracellular Ca2+ levels. TGase2 played a critical role in high glucose-induced ovarian cancer cell migration and invasion through ß-catenin disassembly. Human C-peptide inhibited high glucose-induced disassembly of adherens junctions and ovarian cancer cell migration and invasion through inhibition of ROS generation and TGase2 activation. The preventive effect of C-peptide on high glucose-induced ovarian cancer cell migration and invasion was further demonstrated in ID8 murine ovarian cancer cells. Our findings suggest that high glucose conditions induce the migration and invasion of ovarian cancer cells, and human C-peptide inhibits these metastatic responses by preventing ROS generation, TGase2 activation, and subsequent disassembly of adherens junctions.
Assuntos
Neoplasias Ovarianas , Humanos , Animais , Camundongos , Feminino , Peptídeo C/farmacologia , Espécies Reativas de Oxigênio/farmacologia , Neoplasias Ovarianas/patologia , Movimento Celular , Glucose/farmacologiaRESUMO
Rationale: Neovascularization is a hallmark of the late stages of diabetic retinopathy (DR) leading to blindness. The current anti-DR drugs have clinical disadvantages including short circulation half-lives and the need for frequent intraocular administration. New therapies with long-lasting drug release and minimal side effects are therefore needed. We explored a novel function and mechanism of a proinsulin C-peptide molecule with ultra-long-lasting delivery characteristics for the prevention of retinal neovascularization in proliferative diabetic retinopathy (PDR). Methods: We developed a strategy for ultra-long intraocular delivery of human C-peptide using an intravitreal depot of K9-C-peptide, a human C-peptide conjugated to a thermosensitive biopolymer, and investigated its inhibitory effect on hyperglycemia-induced retinal neovascularization using human retinal endothelial cells (HRECs) and PDR mice. Results: In HRECs, high glucose conditions induced oxidative stress and microvascular permeability, and K9-C-peptide suppressed those effects similarly to unconjugated human C-peptide. A single intravitreal injection of K9-C-peptide in mice resulted in the slow release of human C-peptide that maintained physiological levels of C-peptide in the intraocular space for at least 56 days without inducing retinal cytotoxicity. In PDR mice, intraocular K9-C-peptide attenuated diabetic retinal neovascularization by normalizing hyperglycemia-induced oxidative stress, vascular leakage, and inflammation and restoring blood-retinal barrier function and the balance between pro- and anti-angiogenic factors. Conclusions: K9-C-peptide provides ultra-long-lasting intraocular delivery of human C-peptide as an anti-angiogenic agent to attenuate retinal neovascularization in PDR.
Assuntos
Diabetes Mellitus , Retinopatia Diabética , Hiperglicemia , Neovascularização Retiniana , Humanos , Camundongos , Animais , Neovascularização Retiniana/tratamento farmacológico , Retinopatia Diabética/tratamento farmacológico , Peptídeo C/farmacologia , Peptídeo C/uso terapêutico , Células Endoteliais , Neovascularização Patológica/tratamento farmacológico , Hiperglicemia/tratamento farmacológicoRESUMO
Traditional medicines are recently being focused on to treat diabetes and its complications because of their lack of toxic and/or side effects. This report describes the effects of 7-O-galloyl-D-sedoheptulose (GS), a polyphenolic compound isolated from Corni Fructus, on type 2 diabetic db/db mice with hepatic and pancreatic damage. We examined several biochemical factors and oxidative stress- and inflammation-related markers. In the serum, levels of glucose, leptin, insulin, C-peptide, resistin, tumor necrosis factor-α, and interleukin-6 were down-regulated, while adiponectin was augmented by GS treatment. In addition, GS suppressed the reactive oxygen species and lipid peroxidation in the serum, liver, and pancreas, but increased the pancreatic insulin and pancreatic C-peptide contents. These results were derived from attenuating the expression of nicotinamide adenine dinucleotide phosphate oxidase subunit proteins, Nox-4 and p22phox. Augmented nuclear factor (NF)-E2-related factor 2 and heme oxygenase-1 were reduced with a decrease in oxidative stress during GS treatment. NF-κB-related pro-inflammatory factors were also alleviated in hepatic tissue. Moreover, GS modulated the protein expressions of pro-inflammatory NF-κB, cyclooxygenase-2, inducible nitric oxide synthase, c-Jun N-terminal kinase (JNK), phosphor-JNK, activator protein-1, transforming growth factor-ß1, and fibronectin. Based on these results, we demonstrated that the anti-diabetic action of GS may be due to its anti-oxidative stress property and anti-inflammatory action.
Assuntos
Cornus , Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Camundongos , Animais , Cornus/química , Diabetes Mellitus Tipo 2/complicações , Polifenóis/farmacologia , Polifenóis/metabolismo , Polifenóis/uso terapêutico , NF-kappa B/metabolismo , NF-kappa B/farmacologia , NF-kappa B/uso terapêutico , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/metabolismo , Peptídeo C/metabolismo , Peptídeo C/farmacologia , Peptídeo C/uso terapêutico , Fígado , Pâncreas/metabolismo , Pâncreas/patologia , Insulina/farmacologiaRESUMO
Importance: Near normalization of glucose levels instituted immediately after diagnosis of type 1 diabetes has been postulated to preserve pancreatic beta cell function by reducing glucotoxicity. Previous studies have been hampered by an inability to achieve tight glycemic goals. Objective: To determine the effectiveness of intensive diabetes management to achieve near normalization of glucose levels on preservation of pancreatic beta cell function in youth with newly diagnosed type 1 diabetes. Design, Setting, and Participants: This randomized, double-blind, clinical trial was conducted at 6 centers in the US (randomizations from July 20, 2020, to October 13, 2021; follow-up completed September 15, 2022) and included youths with newly diagnosed type 1 diabetes aged 7 to 17 years. Interventions: Random assignment to intensive diabetes management, which included use of an automated insulin delivery system (n = 61), or standard care, which included use of a continuous glucose monitor (n = 52), as part of a factorial design in which participants weighing 30 kg or more also were assigned to receive either oral verapamil or placebo. Main Outcomes and Measures: The primary outcome was mixed-meal tolerance test-stimulated C-peptide area under the curve (a measure of pancreatic beta cell function) 52 weeks from diagnosis. Results: Among 113 participants (mean [SD] age, 11.8 [2.8] years; 49 females [43%]; mean [SD] time from diagnosis to randomization, 24 [5] days), 108 (96%) completed the trial. The mean C-peptide area under the curve decreased from 0.57 pmol/mL at baseline to 0.45 pmol/mL at 52 weeks in the intensive management group, and from 0.60 to 0.50 pmol/mL in the standard care group (treatment group difference, -0.01 [95% CI, -0.11 to 0.10]; P = .89). The mean time in the target range of 70 to 180 mg/dL, measured with continuous glucose monitoring, at 52 weeks was 78% in the intensive management group vs 64% in the standard care group (adjusted difference, 16% [95% CI, 10% to 22%]). One severe hypoglycemia event and 1 diabetic ketoacidosis event occurred in each group. Conclusions and Relevance: In youths with newly diagnosed type 1 diabetes, intensive diabetes management, which included automated insulin delivery, achieved excellent glucose control but did not affect the decline in pancreatic C-peptide secretion at 52 weeks. Trial Registration: ClinicalTrials.gov Identifier: NCT04233034.
Assuntos
Diabetes Mellitus Tipo 1 , Células Secretoras de Insulina , Feminino , Adolescente , Humanos , Criança , Diabetes Mellitus Tipo 1/tratamento farmacológico , Hipoglicemiantes/efeitos adversos , Hipoglicemiantes/administração & dosagem , Glicemia/efeitos dos fármacos , Células Secretoras de Insulina/efeitos dos fármacos , Peptídeo C/farmacologia , Peptídeo C/uso terapêutico , Método Duplo-Cego , Controle Glicêmico , Automonitorização da Glicemia , Hemoglobinas Glicadas , Insulina/efeitos adversos , Insulina/administração & dosagemRESUMO
Importance: In preclinical studies, thioredoxin-interacting protein overexpression induces pancreatic beta cell apoptosis and is involved in glucotoxicity-induced beta cell death. Calcium channel blockers reduce these effects and may be beneficial to beta cell preservation in type 1 diabetes. Objective: To determine the effect of verapamil on pancreatic beta cell function in children and adolescents with newly diagnosed type 1 diabetes. Design, Setting, and Participants: This double-blind, randomized clinical trial including children and adolescents aged 7 to 17 years with newly diagnosed type 1 diabetes who weighed 30 kg or greater was conducted at 6 centers in the US (randomized participants between July 20, 2020, and October 13, 2021) and follow-up was completed on September 15, 2022. Interventions: Participants were randomly assigned 1:1 to once-daily oral verapamil (n = 47) or placebo (n = 41) as part of a factorial design in which participants also were assigned to receive either intensive diabetes management or standard diabetes care. Main Outcomes and Measures: The primary outcome was area under the curve values for C-peptide level (a measure of pancreatic beta cell function) stimulated by a mixed-meal tolerance test at 52 weeks from diagnosis of type 1 diabetes. Results: Among 88 participants (mean age, 12.7 [SD, 2.4] years; 36 were female [41%]; and the mean time from diagnosis to randomization was 24 [SD, 4] days), 83 (94%) completed the trial. In the verapamil group, the mean C-peptide area under the curve was 0.66 pmol/mL at baseline and 0.65 pmol/mL at 52 weeks compared with 0.60 pmol/mL at baseline and 0.44 pmol/mL at 52 weeks in the placebo group (adjusted between-group difference, 0.14 pmol/mL [95% CI, 0.01 to 0.27 pmol/mL]; P = .04). This equates to a 30% higher C-peptide level at 52 weeks with verapamil. The percentage of participants with a 52-week peak C-peptide level of 0.2 pmol/mL or greater was 95% (41 of 43 participants) in the verapamil group vs 71% (27 of 38 participants) in the placebo group. At 52 weeks, hemoglobin A1c was 6.6% in the verapamil group vs 6.9% in the placebo group (adjusted between-group difference, -0.3% [95% CI, -1.0% to 0.4%]). Eight participants (17%) in the verapamil group and 8 participants (20%) in the placebo group had a nonserious adverse event considered to be related to treatment. Conclusions and Relevance: In children and adolescents with newly diagnosed type 1 diabetes, verapamil partially preserved stimulated C-peptide secretion at 52 weeks from diagnosis compared with placebo. Further studies are needed to determine the longitudinal durability of C-peptide improvement and the optimal length of therapy. Trial Registration: ClinicalTrials.gov Identifier: NCT04233034.
Assuntos
Diabetes Mellitus Tipo 1 , Células Secretoras de Insulina , Adolescente , Humanos , Criança , Feminino , Masculino , Diabetes Mellitus Tipo 1/tratamento farmacológico , Hipoglicemiantes/uso terapêutico , Peptídeo C/metabolismo , Peptídeo C/farmacologia , Peptídeo C/uso terapêutico , Método Duplo-Cego , Verapamil/efeitos adversos , Células Secretoras de Insulina/efeitos dos fármacosRESUMO
Proinsulin C-peptide has a protective effect against diabetic complications; however, its role in hyperglycemia-induced pulmonary fibrosis is unknown. In this study, we investigated the inhibitory effect of C-peptide on hyperglycemia-induced pulmonary fibrosis and the molecular mechanism of C-peptide action in the lungs of diabetic mice and in human pulmonary microvascular endothelial cells (HPMVECs). We found that, in the lungs of diabetic mice, C-peptide supplementation using osmotic pumps attenuated hyperglycemia-induced pulmonary fibrosis and expression of fibrosis-related proteins. In HPMVECs, C-peptide inhibited vascular endothelial growth factor-induced adherens junction disruption and endothelial cell permeability by inhibiting reactive oxygen species generation and transglutaminase (TGase) activation. In the lungs, C-peptide supplementation suppressed hyperglycemia-induced reactive oxygen species generation, TGase activation, and microvascular leakage. C-peptide inhibited hyperglycemia-induced inflammation and apoptosis, which are involved in the pathological process of pulmonary fibrosis. We also demonstrated the role of TGase2 in hyperglycemia-induced vascular leakage, inflammation, apoptosis, and pulmonary fibrosis in the lungs of diabetic TGase2-null (Tgm2-/-) mice. Furthermore, we demonstrated a long-term inhibitory effect of systemic delivery of C-peptide using K9-C-peptide hydrogels on hyperglycemia-induced fibrosis in diabetic lungs. Overall, our findings suggest that C-peptide alleviates hyperglycemia-induced pulmonary fibrosis by inhibiting TGase2-mediated microvascular leakage, inflammation, and apoptosis in diabetes.
Assuntos
Diabetes Mellitus Experimental , Hiperglicemia , Fibrose Pulmonar , Animais , Peptídeo C/farmacologia , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/metabolismo , Células Endoteliais/metabolismo , Hiperglicemia/complicações , Hiperglicemia/tratamento farmacológico , Hiperglicemia/metabolismo , Inflamação/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Proteína 2 Glutamina gama-Glutamiltransferase , Fibrose Pulmonar/complicações , Fibrose Pulmonar/etiologia , Espécies Reativas de Oxigênio/metabolismo , Transglutaminases/genética , Transglutaminases/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
BACKGROUND AND AIM: Disordered hepatic energy metabolism is found in obese rats with insulin resistance (IR). There are insufficient experimental studies of electroacupuncture (EA) for IR and type 2 diabetes mellitus (T2DM). The aim of this study was to probe the effect of EA on disordered hepatic energy metabolism and the adenosine monophosphate (AMP)-activated protein kinase (AMPK)/mammalian target of rapamycin complex 1 (mTORC1)/ribosomal protein S6 kinase, 70-kDa (p70S6K) signaling pathway. METHODS: Zucker Diabetic Fatty (ZDF) rats were randomly divided into three groups: EA group receiving EA treatment; Pi group receiving pioglitazone gavage; and ZF group remaining untreated (n = 8 per group). Inbred non-insulin-resistant Zucker lean rats formed an (untreated) healthy control group (ZL, n = 8). Fasting plasma glucose (FPG), fasting insulin (FINS), C-peptide, C-reactive protein (CRP) and homeostatic model assessment of insulin resistance (HOMA-IR) indices were measured. Hematoxylin-eosin (H&E) staining was used to investigate the liver morphologically. The mitochondrial structure of hepatocytes was observed by transmission electron microscopy (TEM). Western blotting was adopted to determine protein expression of insulin receptor substrate 1 (IRS-1), mTOR, mTORC1, AMPK, tuberous sclerosis 2 (TSC2) and p70S6K, and their phosphorylation. RT-PCR was used to quantify IRS-1, mTOR, mTORC1, AMPK and p70S6K mRNA levels. RESULTS: Compared with the ZF group, FPG, FINS, C-peptide, CRP and HOMA-IR levels were significantly reduced in the EA group (p < 0.05, p < 0.01). Evaluation of histopathology showed improvement in liver appearances following EA. Phosphorylation levels of AMPK, mTOR and TSC2 decreased, and IRS-1 and p70S6K increased, in hepatocytes of the ZF group, while these negative effects appeared to be alleviated by EA. CONCLUSIONS: EA can effectively ameliorate IR and regulate energy metabolism in the ZDF rat model. AMPK/mTORC1/p70S6K and related molecules may represent a potential mechanism of action underlying these effects.
Assuntos
Diabetes Mellitus Tipo 2 , Eletroacupuntura , Resistência à Insulina , Proteínas Quinases Ativadas por AMP/metabolismo , Animais , Peptídeo C/metabolismo , Peptídeo C/farmacologia , Diabetes Mellitus Tipo 2/terapia , Metabolismo Energético , Insulina/metabolismo , Mamíferos/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Ratos , Ratos Zucker , Proteínas Quinases S6 Ribossômicas 70-kDa/genética , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo , Proteínas Quinases S6 Ribossômicas 70-kDa/farmacologia , Transdução de Sinais , Serina-Treonina Quinases TOR/genética , Serina-Treonina Quinases TOR/metabolismo , Serina-Treonina Quinases TOR/farmacologiaRESUMO
BACKGROUND: Nitrite stimulates insulin secretion from pancreatic ß-cells; however, the underlying mechanisms have not been completely addressed. The aim of this study is to determine effect of nitrite on gene expression of SNARE proteins involved in insulin secretion from isolated pancreatic islets in Type 2 diabetic Wistar rats. METHODS: Three groups of rats were studied (n = 10/group): Control, diabetes, and diabetes + nitrite, which treated with sodium nitrite (50 mg/L) for 8 weeks. Type 2 diabetes was induced using a low-dose of streptozotocin (25 mg/kg) combined with high-fat diet. At the end of the study, pancreatic islets were isolated and mRNA expressions of interested genes were measured; in addition, protein expression of proinsulin and C-peptide in pancreatic tissue was assessed using immunofluorescence staining. RESULTS: Compared with controls, in the isolated pancreatic islets of Type 2 diabetic rats, mRNA expression of glucokinase (59%), syntaxin1A (49%), SNAP25 (70%), Munc18b (48%), insulin1 (56%), and insulin2 (52%) as well as protein expression of proinsulin and C-peptide were lower. In diabetic rats, nitrite administration significantly increased gene expression of glucokinase, synaptotagmin III, syntaxin1A, SNAP25, Munc18b, and insulin genes as well as increased protein expression of proinsulin and C-peptide. CONCLUSION: Stimulatory effect of nitrite on insulin secretion in Type 2 diabetic rats is at least in part due to increased gene expression of molecules involved in glucose sensing (glucokinase), calcium sensing (synaptotagmin III), and exocytosis of insulin vesicles (syntaxin1A, SNAP25, and Munc18b) as well as increased expression of insulin genes.
Assuntos
Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Ilhotas Pancreáticas , Animais , Peptídeo C/genética , Peptídeo C/metabolismo , Peptídeo C/farmacologia , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Expressão Gênica , Glucoquinase/genética , Glucoquinase/metabolismo , Glucoquinase/farmacologia , Glucose/metabolismo , Humanos , Secreção de Insulina , Ilhotas Pancreáticas/metabolismo , Masculino , Nitritos/metabolismo , Nitritos/farmacologia , Proinsulina/genética , Proinsulina/metabolismo , Proinsulina/farmacologia , RNA Mensageiro , Ratos , Ratos Wistar , Sinaptotagminas/genética , Sinaptotagminas/metabolismo , Sinaptotagminas/farmacologiaRESUMO
Several studies have associated the presence of residual insulin secretion capability (also referred to as being C-peptide positive) with lower risk of insulin-induced hypoglycemia in patients with type 1 diabetes (T1D), although the reason is unclear. We tested the hypothesis that C-peptide infusion would enhance glucagon secretion in response to hyperinsulinemia during euglycemic and hypoglycemic conditions in dogs (5 male/4 female). After a 2-hour basal period, an intravenous (IV) infusion of insulin was started, and dextrose was infused to maintain euglycemia for 2 hours. At the same time, an IV infusion of either saline (SAL) or C-peptide (CPEP) was started. After this euglycemic period, the insulin and SAL/CPEP infusions were continued for another 2 hours, but the glucose was allowed to fall to approximately 50 mg/dL. In response to euglycemic-hyperinsulinemia, glucagon secretion decreased in SAL but remained unchanged from the basal period in CPEP condition. During hypoglycemia, glucagon secretion in CPEP was 2 times higher than SAL, and this increased net hepatic glucose output and reduced the amount of exogenous glucose required to maintain glycemia. These data suggest that the presence of C-peptide during IV insulin infusion can preserve glucagon secretion during euglycemia and enhance it during hypoglycemia, which could explain why T1D patients with residual insulin secretion are less susceptible to hypoglycemia.
Assuntos
Peptídeo C , Glucagon/metabolismo , Hiperinsulinismo/metabolismo , Hipoglicemia/metabolismo , Hipoglicemiantes , Animais , Glicemia/efeitos dos fármacos , Glicemia/metabolismo , Peptídeo C/administração & dosagem , Peptídeo C/farmacologia , Diabetes Mellitus Tipo 1 , Cães , Feminino , Hipoglicemiantes/administração & dosagem , Hipoglicemiantes/farmacologia , MasculinoRESUMO
The podocyte is one of the main components of the glomerular filtration barrier in the kidney, and its injury may contribute to proteinuria, glomerulosclerosis and eventually kidney failure. C-peptide, a cleavage product of proinsulin, shows therapeutic potential for treating diabetic nephropathy (DN). The aim of this study was to investigate the effect of C-peptide on high glucose-induced podocyte dysfunction. In the present study, we found that the protective effects of islet transplantation were superior to simple insulin therapy for the treatment of DN in streptozotocin (STZ)-treated rats. And such superiority may due to the function of C-peptide secreted at the implanted site. Based on this background, we determined that the application of C-peptide significantly prevented high glucose-induced podocyte injury by increasing the expression of nephrin and synaptopodin. Meanwhile, C-peptide suppressed high glucose-induced epithelial-mesenchymal transition (EMT) and renal fibrosis via decreasing the expression of snail, vimentin, α-smooth muscle actin (α-SMA) and connective tissue growth factor (CTGF). Moreover, the Notch and transforming growth factor-ß (TGF-ß) signaling pathways were activated by high glucose, and treatment with C-peptide down-regulated the expression of the Notch signaling molecules Notch 1 and Jagged 1 and the TGF-ß signaling molecule TGF-ß1. These findings suggested that C-peptide might serve as a novel treatment method for DN and podocyte dysfunction.
Assuntos
Peptídeo C/farmacologia , Diabetes Mellitus Experimental/complicações , Nefropatias Diabéticas/terapia , Glucose/toxicidade , Podócitos/efeitos dos fármacos , Receptores Notch/metabolismo , Fator de Crescimento Transformador beta1/metabolismo , Animais , Nefropatias Diabéticas/etiologia , Nefropatias Diabéticas/metabolismo , Nefropatias Diabéticas/patologia , Hipoglicemiantes/farmacologia , Insulina/farmacologia , Transplante das Ilhotas Pancreáticas , Masculino , Podócitos/metabolismo , Podócitos/patologia , Ratos , Ratos Wistar , Receptores Notch/genética , Edulcorantes/toxicidade , Fator de Crescimento Transformador beta1/genéticaRESUMO
The C-peptide is a fragment of proinsulin, the cleavage of which forms active insulin. In recent years, new information has appeared on the physiological effects of the C-peptide, indicating its positive effect on many organs and tissues, including the kidneys, nervous system, heart, vascular endothelium and blood microcirculation. Studies on experimental models of diabetes mellitus in animals, as well as clinical trials in patients with diabetes, have shown that the C-peptide has an important regulatory effect on the early stages of functional and structural disorders caused by this disease. The C-peptide exhibits its effects through binding to a specific receptor on the cell membrane and activation of downstream signaling pathways. Intracellular signaling involves G-proteins and Ca2+-dependent pathways, resulting in activation and increased expression of endothelial nitric oxide synthase, Na+/K+-ATPase and important transcription factors involved in apoptosis, anti-inflammatory and other intracellular defense mechanisms. This review gives an idea of the C-peptide as a bioactive endogenous peptide that has its own biological activity and therapeutic potential.
Assuntos
Peptídeo C , Diabetes Mellitus Tipo 1 , Animais , Anti-Inflamatórios/farmacologia , Peptídeo C/farmacologia , Diabetes Mellitus Tipo 1/tratamento farmacológico , Humanos , Insulina , Transdução de Sinais/efeitos dos fármacosRESUMO
Type 1 diabetes mellitus (T1DM) is characterized by C-peptide deficiency and elevated levels of pro-inflammatory cytokines. The aim of this study was to investigate the role of C-peptide in renal and inflammatory complications in streptozotocin (STZ)-diabetic mice model of T1DM with kidney disease. The study was performed in 8-week old male C57BL/6 mice. Two streptozotocin-diabetic groups (a T1DM animal model), after 4 weeks of diabetes, were treated with subcutaneous infusion of either vehicle (n = 12) or C-peptide (n = 11). Two non-diabetic groups (vehicle, n = 10; C-peptide, n = 9) were treated using the same protocol as described for the diabetic mice. The treatment with C-peptide in the diabetic group reduced the urinary levels of IL17 and TNFα, as well as IL4 and IL10 (p < 0.05). Contrary, the diabetic + C-peptide group presented higher IL10 gene expression in kidney. Besides, it displayed a reduction of TNFα gene expression. The data suggest that C-peptide may modulate pro- and anti-inflammatory signalling pathways, resulting in attenuation of kidney inflammation in T1DM animal model.
Assuntos
Anti-Inflamatórios/farmacologia , Peptídeo C/farmacologia , Diabetes Mellitus Tipo 1/metabolismo , Rim/efeitos dos fármacos , Animais , Citocinas/urina , Diabetes Mellitus Experimental , Inflamação/metabolismo , Rim/metabolismo , Nefropatias/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
In type 1 diabetes mellitus, the levels of insulin and C-peptide decrease at the periphery and in CNS. C-peptide potentiates the regulatory effects of insulin. We studied the effects of single and repeated (over 7 days) individual and combined nasal administration of C-peptide (10 µg/day) and insulin (20 µg/day) on activity of Akt kinase and kinase-3ß-glycogen synthase (GSK3ß), the components of 3-phosphoinositide pathway, in the hypothalamus of intact rats and rats with mild streptozotocin-induced type 1 diabetes mellitus. Phosphorylation of Akt kinase at Thr308 and Ser473 (stimulation) and GSK3ß at Ser9 (inhibition) was evaluated. In diabetes, phosphorylation of Akt kinase and, to a lesser extent, GSK3ß, is reduced. A single injection of insulin or C-peptide and insulin increased this process. Long-term combined treatment with C-peptide and insulin normalized activity of Akt kinase and GSK3ß in diabetic rats, treatment with insulin alone produced less pronounced effect; monotherapy with C-peptide was ineffective. Intranasal co-administration of C-peptide and insulin effectively stimulates the insulin system in the hypothalamus that is weakened at diabetes mellitus type 1, which can be used in the treatment of this disease.
Assuntos
Peptídeo C/farmacologia , Diabetes Mellitus Experimental/tratamento farmacológico , Hipotálamo/metabolismo , Insulina/farmacologia , Fosfatidilinositóis/metabolismo , Administração Intranasal , Animais , Peptídeo C/administração & dosagem , Sinergismo Farmacológico , Índice Glicêmico/efeitos dos fármacos , Glicogênio Sintase Quinase 3 beta/metabolismo , Masculino , Fosforilação , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Ratos Wistar , Estreptozocina , Redução de Peso/efeitos dos fármacosRESUMO
C-peptide has emerged as a potential drug for treating diabetic complications. However, clinical application of C-peptide is limited by its short half-life during circulation and costly synthesis methods. To overcome these limitations, a biocompatible and thermosensitive biopolymer-C-peptide conjugate composed of human C-peptide genetically conjugated at the C-terminus of nine repeats of lysine-containing elastin-like polypeptide (K9-C-peptide) is generated. K9-C-peptide exhibits reversible thermal phase behavior with a transition temperature dependent on polypeptide concentration. Degradation of K9-C-peptide hydrogel depends on the concentration of four cleavage enzymes as well as the reaction time and frequency of treatments with elastase-2. The preventive effect of K9-C-peptide against high glucose-induced human aortic endothelial cell dysfunction is further investigated. K9-C-peptide inhibits high glucose-induced intracellular reactive oxygen species generation, transglutaminase 2 activation, and apoptosis, similar to the inhibitory effects of human C-peptide. Thus, K9-C-peptide is a potential drug depot for the sustained delivery of C-peptide to treat diabetic complications.
Assuntos
Biopolímeros/farmacologia , Peptídeo C/farmacologia , Células Endoteliais/patologia , Glucose/toxicidade , Temperatura , Sequência de Aminoácidos , Apoptose/efeitos dos fármacos , Peptídeo C/química , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/enzimologia , Ativação Enzimática/efeitos dos fármacos , Proteínas de Ligação ao GTP/metabolismo , Humanos , Peptídeo Hidrolases/metabolismo , Proteína 2 Glutamina gama-Glutamiltransferase , Proteólise/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Transglutaminases/metabolismoRESUMO
The repair capacity of progenitor skeletal muscle satellite cells (SC) in Type 1 diabetes mellitus (T1DM) is decreased. This is associated with the loss of skeletal muscle function. In T1DM, the deficiency of C-peptide along with insulin is associated with an impairment of skeletal muscle functions such as growth, and repair, and is thought to be an important contributor to increased morbidity and mortality. Recently, cholesterol-lowering drugs (statins) have also been reported to increase the risk of skeletal muscle dysfunction. We hypothesised that C-peptide activates key signaling pathways in myoblasts, thus promoting cell survival and protecting against simvastatin-induced myotoxicity. This was tested by investigating the effects of C-peptide on the L6 rat myoblast cell line under serum-starved conditions. Results: C-peptide at concentrations as low as 0.03 nM exerted stimulatory effects on intracellular signaling pathways-MAP kinase (ERK1/2) and Akt. When apoptosis was induced by simvastatin, 3 nM C-peptide potently suppressed the apoptotic effect through a pertussis toxin-sensitive pathway. Simvastatin strongly impaired Akt signaling and stimulated the reactive oxygen species (ROS) production; suggesting that Akt signaling and oxidative stress are important factors in statin-induced apoptosis in L6 myoblasts. The findings indicate that C-peptide exerts an important protective effect against death signaling in myoblasts. Therefore, in T1DM, the deficiency of C-peptide may contribute to myopathy by rendering myoblast-like progenitor cells (involved in muscle regeneration) more susceptible to the toxic effects of insults such as simvastatin.
Assuntos
Peptídeo C/farmacologia , Doenças Musculares/induzido quimicamente , Doenças Musculares/patologia , Mioblastos/patologia , Sinvastatina/efeitos adversos , Animais , Caspase 3/metabolismo , Morte Celular/efeitos dos fármacos , Linhagem Celular , Forma Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Músculo Esquelético/patologia , Doenças Musculares/metabolismo , Mioblastos/efeitos dos fármacos , Mioblastos/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
Diabetes is associated with poor oocyte quality and the dysregulation of ovarian function and is thus a leading contributor to the increasing prevalence of female reproductive pathologies. Accordingly, it is well-established that insulin fulfills a key role in the regulation of several facets of female reproduction. What remains less certain is whether proinsulin C-peptide, which has recently been implicated in cellular signaling cascades, holds a functional role in the female germline. In the present study, we examined the expression of insulin, C-peptide, and its purported receptor; GPR146, within the mouse ovary and oocyte. Our data establish the presence of abundant C-peptide within follicular fluid and raise the prospect that this bioactive peptide is internalized by oocytes in a G-protein coupled receptor-dependent manner. Further, our data reveal that internalized C-peptide undergoes pronounced subcellular relocalization from the ooplasm to the pronuclei postfertilization. The application of immunoprecipitation analysis and mass spectrometry identified breast cancer type 2 susceptibility protein (BRCA2), the meiotic resumption/DNA repair protein, as a primary binding partner for C-peptide within the oocyte. Collectively, these findings establish a novel accumulation profile for C-peptide in the female germline and provide the first evidence for an interaction between C-peptide and BRCA2. This interaction is particularly intriguing when considering the propensity for oocytes from diabetic women to experience aberrant meiotic resumption and perturbation of traditional DNA repair processes. This therefore provides a clear imperative for further investigation of the implications of dysregulated C-peptide production in these individuals.
Assuntos
Peptídeo C/genética , Desenvolvimento Embrionário , Oócitos/metabolismo , Oogênese , Animais , Proteína BRCA2/genética , Proteína BRCA2/metabolismo , Blastocisto/citologia , Blastocisto/efeitos dos fármacos , Peptídeo C/metabolismo , Peptídeo C/farmacologia , Células Cultivadas , Células do Cúmulo/citologia , Células do Cúmulo/efeitos dos fármacos , Células do Cúmulo/metabolismo , Desenvolvimento Embrionário/efeitos dos fármacos , Desenvolvimento Embrionário/genética , Feminino , Fertilização in vitro/veterinária , Células Germinativas/citologia , Células Germinativas/efeitos dos fármacos , Células Germinativas/metabolismo , Técnicas de Maturação in Vitro de Oócitos/métodos , Técnicas de Maturação in Vitro de Oócitos/veterinária , Masculino , Meiose/efeitos dos fármacos , Meiose/genética , Meiose/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Oócitos/citologia , Oócitos/efeitos dos fármacos , Oogênese/efeitos dos fármacos , Oogênese/genéticaRESUMO
Diabetes and cardiometabolic risk factors including hypertension and dyslipidemia are the major threats to human health in the 21st century. Apoptosis in pancreatic tissue is one of the major causes of diabetes type 1 progression. The aim of this study was to investigate the effects of C-peptide or l-arginine on some cardiometabolic risk factors, pancreatic morphology, function and apoptosis, and the mechanisms of their actions. Forty adult male albino rats were divided into four equal groups: 1-control nondiabetic, 2-diabetic (no treatment), 3-diabetic + C-peptide, and 4-diabetic + l-arginine. Diabetes was induced by a single intraperitoneal injection of high dose streptozotocin. At the end of the experiment, sera glucose, insulin levels, total antioxidant capacity (TAC), malondialdehyde (MDA), nitric oxide (NO), and pancreatic MDA, TAC, and B-cell lymphoma 2 were measured. The morphology and proliferating activity of the pancreas were examined by hematoxylin and eosin histological stain, proliferative cell nuclear antigen (PCNA), and insulin antibodies. Our results showed that induction of diabetes caused hyperglycemia, dyslipidemia, and oxidative stress. However, administration of C-peptide or l-arginine significantly improved the pancreatic histopathology with a significant increase in the area % of insulin immunoreactivity, the number of PCNA immunopositive cells, the number of islets, and the diameter of islets compared with the diabetic group. C-peptide treatment of the diabetic rats completely corrected these errors, while l-arginine partially antagonized the above diabetic complications. So the administration of C-peptide as an adjuvant therapy in type 1 diabetes can significantly decrease apoptosis of pancreas and subsequent progression of diabetes complication.
Assuntos
Arginina/farmacologia , Peptídeo C/farmacologia , Proliferação de Células/efeitos dos fármacos , Diabetes Mellitus Experimental , Células Secretoras de Insulina/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Animais , Glicemia , Regulação da Expressão Gênica/efeitos dos fármacos , Insulina/sangue , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/fisiologia , Masculino , Antígeno Nuclear de Célula em Proliferação/genética , Antígeno Nuclear de Célula em Proliferação/metabolismo , Ratos , Ratos Sprague-DawleyRESUMO
C-peptide has a beneficial effect against diabetic complications, but its role in hyperglycemia-induced metastasis is unknown. We investigated hyperglycemia-mediated pulmonary vascular leakage and metastasis and C-peptide inhibition of these molecular events using human pulmonary microvascular endothelial cells (HPMVECs) and streptozotocin-induced diabetic mice. VEGF, which is elevated in the lungs of diabetic mice, activated transglutaminase 2 (TGase2) in HPMVECs by sequential elevation of intracellular Ca2+ and reactive oxygen species (ROS) levels. VEGF also induced vascular endothelial (VE)-cadherin disruption and increased the permeability of endothelial cells, both of which were prevented by the TGase inhibitors monodansylcadaverine and cystamine or TGM2-specific small interfering RNA. C-peptide prevented VEGF-induced VE-cadherin disruption and endothelial cell permeability through inhibiting ROS-mediated activation of TGase2. C-peptide supplementation inhibited hyperglycemia-induced ROS generation and TGase2 activation and prevented vascular leakage and metastasis in the lungs of diabetic mice. The role of TGase2 in hyperglycemia-induced pulmonary vascular leakage and metastasis was further demonstrated in diabetic Tgm2-/- mice. These findings demonstrate that hyperglycemia induces metastasis, and C-peptide prevents the hyperglycemia-induced metastasis in the lungs of diabetic mice by inhibiting VEGF-induced TGase2 activation and subsequent vascular leakage.-Jeon, H.-Y., Lee, Y.-J., Kim, Y.-S., Kim, S.-Y., Han, E.-T., Park, W. S., Hong, S.-H., Kim, Y.-M., Ha, K.-S. Proinsulin C-peptide prevents hyperglycemia-induced vascular leakage and metastasis of melanoma cells in the lungs of diabetic mice.
Assuntos
Peptídeo C/farmacologia , Diabetes Mellitus Experimental/fisiopatologia , Hiperglicemia/complicações , Neoplasias Pulmonares/tratamento farmacológico , Melanoma Experimental/tratamento farmacológico , Neovascularização Patológica/tratamento farmacológico , Animais , Apoptose , Feminino , Proteínas de Ligação ao GTP/fisiologia , Células Endoteliais da Veia Umbilical Humana , Humanos , Hiperglicemia/metabolismo , Hiperglicemia/patologia , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/secundário , Masculino , Melanoma Experimental/metabolismo , Melanoma Experimental/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neovascularização Patológica/metabolismo , Neovascularização Patológica/patologia , Proteína 2 Glutamina gama-Glutamiltransferase , Espécies Reativas de Oxigênio/metabolismo , Transglutaminases/fisiologia , Fator A de Crescimento do Endotélio Vascular/metabolismoRESUMO
Diabetes mellitus (DM) is closely associated with male infertility and sexual dysfunction. Recent data indicate that the proinsulin C-peptide (CP) exerts important physiological effects and shows the characteristics of an endogenous peptide hormone. So, this study was done to investigate the effect of C-peptide with or without insulin treatment on testicular function and architecture in diabetic rats. Rats were divided into the following groups: control, diabetic, and diabetic groups treated with either CP alone or combined with insulin. Tested parameters included, estimation of serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone, and glucose levels, testicular samples for histopathology and estimation of malondialdehyde (MDA), total antioxidant capacity (TAC), and B-cell leukemia/lymphoma-2 (BCL-2) levels as well as sperm count and motility. Results showed that DM caused a severe alteration in hormonal profile and reduced sperm parameters along with increased MDA and decrease in both TAC and BCL-2 levels. CP alone or with insulin treatment efficiently reversed all the negative effects of DM on rat testes, with maximum improvement in the combined regimen. Proposed mechanisms may involve its hypoglycemic, antioxidant, and antiapoptotic properties. Thus, CP could substitute for or better combined with insulin to prevent or retard diabetic-induced testicular dysfunction.