Traitement médicamenteux du diabète de type 2 (première partie)

Rational Design by Structural Biology of Industrializable, Long-Acting Antihyperglycemic GLP-1 Receptor Agonists

Glucagon-like peptide-1 (GLP-1) is easily degraded by dipeptidyl peptidase-4 (DPP-4) in the human body, limiting its therapeutic effect on type II diabetes. Therefore, improving GLP-1 receptor agonist (GLP-1RA) stability is a major obstacle for drug development. We analyzed human GLP-1, DPP-4, and GLP-1 receptor structures and designed three GLP-1RAs, which were introduced into fusion protein fragments and changed in the overall conformation. This modification effectively prevented GLP-1RAs from entering the DPP-4 active center without affecting GLP-1RAs’ ability to bind to GLP-1R, the new GLP-1RA hypoglycemic effect lasting for >24 h. Through molecular modeling, molecular dynamics calculation, and simulation, possible tertiary structure models of GLP-1RAs were obtained; molecular docking with DPP-4 and GLP-1R showed access to the fusion protein. The overall conformational change of GLP-1RAs prevented DPP-4 binding, without affecting GLP-1RAs’ affinity to GLP-1R. This study provides important drug design ideas for GLP-1RA development and a new example for application of structural biology-based protein design in drug development.

Novel GLP-1/anti-apolipoprotein B bifunctional fusion protein alleviates diabetes and diabetic complications in combination with low-intensity ultrasound

AIMS

To engineer and screen a novel GLP-1/anti-apolipoprotein B (apoB) bifunctional fusion protein with therapeutic potential on alleviating diabetes and diabetic complication in combination with low-intensity ultrasound.

MAIN METHODS

Anti-apoB antibodies were screened by phage display technology and further fused to mutated GLP-1 (7-37) via light or heavy fusion to generate bifunctional fusion protein (termed aBG). The optimal design of aBG fusion protein was further confirmed by in vitro epitope competition assay and cAMP accumulation assay. Subsequently, chronic study in DIO mice were subjected to assess the long-term efficacy of screened fusion protein.

KEY FINDINGS

The selected GLP-1/anti-apoB fusion protein, aBG-8, exerted either the highest binding affinities for GLP-1R and apoB, or the greatest LDL-C uptake capacity and GLP-1R activation activity. After 60-day treatment in DIO mice, aBG-8 was proved to exert the promising improvement on hyperglycemia, hyperlipidemia, and obesity in DIO mice. Furthermore, combined therapy of aBG-8 and low-intensity ultrasound could accelerate skin wound closure in diabetic mice.

SIGNIFICANCE

A novel long-lasting bifunctional fusion molecule, aBG-8, was designed with the enormous potential on alleviating diabetes and diabetic complications in combination with low-intensity ultrasound.

Design and evaluation of GLP-1 receptor G-protein biased agonist with prolonged efficacy on diabetes

AIM

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have emerged as potent drug development target for treating diabetes and obesity. Here, we designed and evaluated novel long-acting GLP-1R G protein biased agonist with potent clinical application.

MAIN METHODS

GLP-1R G-protein biased sequences were screened via a high-throughput autocrine-based strategy and then fused to Exendin (9-39). These fusion peptides were further performed with site-specific modification. Surface plasmon resonance (SPR) measurements, GLP-1R activation potencies and plasma stability tests were applied to screen optimal candidate. Acute and chronic hypoglycemic and insulinotropic activities of selected agent were evaluated in diabetic and obese rodent animals.

MAIN FINDINGS

AX09 exert highest binding affinities for GLP-1R extracellular domain (GLP-1R ECD). Further in vitro plasma stability and GLP-1R activation assays demonstrated better potency of AX18. Acute pharmacodynamic evaluation of AX18 demonstrated the promising insulinotropic and hypoglycemic activities which were exhibited in a dose-dependent manner. Prolonged hypoglycemic efficacies of AX18 were also observed in both hypoglycemic duration test and multiple oral glucose tolerance tests (OGTTs) in the diabetic mice. Further pharmacokinetic test in cynomolgus monkeys exhibited that the half-life of AX18 was more than 6 days. Once weekly treatment of AX18 in diabetic mice for 8-week achieved significantly improved %HbA1C, insulin resistance, glucose tolerance, β-cells and diabetic retinal injury. Chronic treatment of AX18 in diet-induced obese (DIO) mice also exhibited beneficial efficacies on %HbA1C, inflammation-related factors lowering, and weight gains.

CONCLUSION

AX18, as a novel GLP-1R G protein biased agonist, exhibited potency for treating diabetes mellitus and its complications.

Sinomenine improve diabetic nephropathy by inhibiting fibrosis and regulating the JAK2/STAT3/SOCS1 pathway in streptozotocin-induced diabetic rats

AIMS

To investigate the therapeutic effects and potent mechanism of sinomenine (SIN) nanoliposomes on nephropathy in diabetic rats.

MAIN METHODS

The protective efficacies of SIN on the oxidative injury in renal HK-2 cell induced by hydrogen peroxide (H₂O₂) were investigated via the CCK-8 assay. Forty SD rats with streptozotocin (STZ)-induced diabetic kidney disease (DKD) were assigned to the saline group and three SIN groups (10, 20 and 40 mg/kg). During 6-week treatment, body weight, fasting glucose level and other metabolic parameters were recorded. H&E staining and changes in renal functions as well as expression levels of apoptosis and fibrosis-related factors in renal tissues were assessed. The qPCR and western blotting (WB) methods were used to detect relative expression levels of JAK/STAT/SOCS pathway-related factors in the renal tissues.

KEY FINDINGS

Cell viabilities of HK-2 cells with oxidative injury were obviously improved by incubating with SIN at 320 μg/mL for 92.9%. Significantly up-regulated GPX1, SOD2 and GSH contributed to the down-regulated ROS content in SIN-treated groups. Moreover, 6-week administration of SIN improved renal functions and worsening nephropathy morphology of DKD rats. SIN also ameliorated gradually increased renal cell apoptosis, suppressed expression levels of fibrosis-related proteins as well as IL-6 and ICAM-1, and regulated JAK2/STAT3/SOCS1 pathway, thereby exhibited protective effects on renal tissues of DKD rats.

CONCLUSION

SIN protects nephrocytes and decreases renal tissue injury via inhibiting oxidative stress, reducing renal cell apoptosis and fibrosis, regulating the JAK2/STAT3/SOCS1 pathway in DKD rats.

Rational design of a GLP-1/GIP/Gcg receptor triagonist to correct hyperglycemia, obesity and diabetic nephropathy in rodent animals

AIMS

To design and screen a potent GLP-1/GIP/Gcg receptors triagonist with therapeutic potential in rodent animals with diabetes and obesity.

MAIN METHODS

First, we obtained a 12-mer dual GIP/Gcg receptor agonist from a large combinatorial peptide library via high-throughput screening technique and then fused to the Exendin (9-39) to generate a potent GLP-1/GIP/Gcg triagonist. Further site fatty chain modification was performed to improve the druggability via enhancing in vivo stability and cyclic half-life. In vitro signaling and functional assays in cell lines expressing each receptor and in vivo efficacy evaluation in rodent model animals with hyperglycemia and obesity were all carefully performed.

KEY FINDINGS

We screened and obtained a potent GLP-1/GIP/Gcg triagonist, termed XFL0, which promotes in vitro GLP-1, GIP, Gcg receptor activation comparable to native GLP-1, GIP and glucagon, respectively. Site-specific fatty acid modification significantly enhanced plasma stability of XFL0 and exhibited no obvious impact on receptor activation. The selected XFL0 conjugates termed XFL6, showed glucose-dependent insulin secretion and improved glucose tolerance by acting on all GLP-1, GIP and Gcg receptors in gene-deficient mice of which the effects were all significantly greater than any single receptor agonist. After chronic treatment in rodent animals with diabetes and obesity, XFL6 potently decreased body weight and food intake, ameliorated the hyperglycemia and hemoglobin A1c levels as well as the lipid metabolism and diabetic nephropathy related disorders.

SIGNIFICANCE

XFL6, as a novel GLP-1/GIP/Gcg receptor triagonist, held potential to deliver outstanding improvement in correcting hyperglycemia, obesity and diabetic nephropathy.

Novel mono-PEGylated dimeric GLP-1 conjugate with enhanced receptor activation and prolonged anti-diabetes efficacies

AIMS

To design and evaluate novel mono-PEGylated dimeric GLP-1 conjugate with enhanced GLP-1 receptor activation and prolonged anti-diabetes efficacies.

MAIN METHODS

All these novel GLP-1 conjugates were produced by using solid-phase synthesis method and further specific cysteine-maleimide modification. In vitro GLP-1R activation assay was performed in CHO cells stably expressing human GLP-1 receptor. The binding affinity for human serum albumin (HSA) in vitro was also conducted using surface plasmon resonance measurement. Subsequently, selected GLP-1 conjugate was subjected to evaluate the acute and chronic efficacies in vivo.

KEY FINDINGS

Four novel glucagon-like peptide-1 (GLP-1) conjugates, termed DIG-1 to DIG-4, were designed and prepared with high purity. Moreover, DIG-1(PEG-5 kDa) and DIG-2 (PEG-10 kDa) exerted ~3-fold and ~2-fold higher potencies of GLP-1R activation than native GLP-1, respectively, and both obviously higher than the DIG-3 (PEG-10 kDa) and DIG-4 (PEG-30 kDa). Then DIG-2 exhibited better in vivo glucose-stabilizing and insulinotropic efficacies than DIG-1 by using multiple oral glucose tests (OGTTs) in SD rats. Furthermore, prolonged glucose-lowering ability of DIG-2 exhibited in hypoglycemic duration test and multiple OGTTs in diabetic db/db mice. Pharmacokinetic data of DIG-2 in cynomolgus monkeys revealed a half-life of ~97.2 h and ~120.4 h after a single subcutaneous (s.c.) administration at doses of 100 and 150 nmol/kg, respectively. Chronic treatment of DIG-2 in db/db mice for consecutive 8-week significantly ameliorate the diabetic symptoms including deteriorative % hemoglobin A1C (HbA1C), glucose tolerance and pancreatic function.

SIGNIFICANCE

DIG-2, as a novel mono-PEGylated dimeric GLP-1 conjugate, holds enhanced receptor activation and prolonged anti-diabetes efficacies.

Rapid selection of a novel GLP-1/GIP dual receptor agonist with prolonged glycemic control and weight loss in rodent animals

BACKGROUND

Glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic polypeptide receptor (GIPR) co-agonists have emerged as treatment options for reversing diabetes and obesity. Here, we screened the high potency receptor-biased GLP-1R agonists via a newly designed high-throughput GLP-1R extracellular domain (ECD)-based system and demonstrated its in vitro and in vivo therapeutic characters.

METHODS

Twelve 9-mer peptides (named XEL1-XEL12) which were screened from a large phage-displayed peptide library were fused to the N-terminus of GIP (3-30) to generate another twelve fusion peptides, termed XEL13-24. Using the six lysine-altered XEL17 as leading sequences, eighteen fatty chain modified fusion peptides were further assessed via in vitro GLP-1R/GIPR-based cell assay. Moreover, the acute and long-acting in vivo effects of selected candidate on diabetic db/db mice and diet-induced obesity (DIO) rats were both carefully evaluated.

RESULTS

XEL17 exhibited balanced activation potency on GLP-1R/GIPR in stable cell lines, and further assessment was performed to evaluate the XEL32, a fatty chain modified XEL17 derivative. Preclinical pharmacodynamic results in diabetic db/db mice demonstrated that XEL32 held outstanding insulinotropic and glucose-lowering activities. In addition, protracted antidiabetic effects of XEL32 were also proved by the hypoglycemic test and multiple oral glucose tolerance test. Furthermore, chronic treatment of XEL32 in DIO rats exhibited outstanding beneficial effects on body weight control, fat loss, food intake control, hemoglobin A1C (HbA1C) reduction as well as the glucose tolerance.

CONCLUSIONS

XEL32, as a novel GLP-1/GIP dual receptor agonist, may supply efficient glycemic control and weight loss.

Design and characterization of novel oxyntomodulin derivatives with potent dual GLP-1/glucagon receptor activation and prolonged antidiabetic effects

AIMS

To investigate the combination of dimerization and PEGylation to enhance the receptor activation and in vivo stability of Oxyntomodulin (OXM).

MAIN METHODS

All LDM peptides were produced by using standard method of solid phase synthesis. The in vitro effects of LDM peptides were assessed by glucagon-like peptide-1 receptor (GLP-1R) and glucagon receptor (GcgR) binding test and Proteolytic stability test. Subsequently, saline, Liraglutide and three doses of LDM-3 treated groups were subjected to the evaluation of aute and long-term efficacy.

KEY FINDINGS

Five long-acting OXM conjugates, termed LDM-1 to LDM-5, were designed using cysteine (Cys)-specific modification reaction including the activated PEG, bisMal-NH₂, and OXM-Cys, and all prepared with high purity. LDM-3 exhibited greater GLP-1R and GcgR activation and ameliorative serum stability. In addition, LDM-3 was identified with enhanced insulinotropic and glycemic abilities in the gene knockout mice. The prolonged glucose-lowering effects of the LDM-3 were proved by hypoglycemic duration test and multiple oral glucose tolerance tests (OGTTs) in the diet-induced obesity (DIO) mice. Furthermore, the pharmacokinetic tests in Sprague Dawley (SD) rat and cynomolgus monkey exhibited the lifespans of LDM-3 at 90 nmol·kg^-1 were 101.5 h and 119.4 h, respectively. Nevertheless, consecutive 8-week administration of LDM-3 improved the cumulative body weight gain, food intake, % HbA1c, glucose tolerance and the pancreatic of the obese mice.

SIGNIFICANCE

LDM-3, as a dual GLP-1R and GcgR agonist, holds potential to be developed as a promising therapeutic candidate for both diabetes and obesity.

Hypoglycaemic effect of Berberis vulgaris L. in normal and streptozotocin-induced diabetic rats

OBJECTIVE

To achieve a primary pharmacological screening contained in the aqueous extract of Berberis vulgaris (B. vulgaris) and to examine the hypoglycaemic effect and biochemical parameters of aqueous and saponins extract on groups of rats rendered diabetic by injection of streptozotocin.

METHODS

The phytochemical tests to detect the presence of different compounds were based on the visual observation of color change or formation of precipitate after the addition of specific reagents. Diabetes was induced in rats by intraperitoneal (i.p.) injection of streptozotocin (STZ) at a dose of 65 mg/kg bw. The fasting blood glucose levels were estimated by glucose oxidase-peroxidase reactive strips (Dextrostix, Bayer Diagnostics). Blood samples were taken by cutting the tip of the tail. Serum cholesterol and serum triglycerides were estimated by enzymatic DHBS colorimetric method.

RESULTS

Administration of 62.5 and 25.0 mg/kg of saponins and aqueous extract respectively in normal rats group shows a significant hypoglycemic activity (32.33% and 40.17% respectively) during the first week. However, diabetic group treated with saponin extract produced a maximum fall of 73.1% and 76.03% at day 1 and day 21 compared to the diabetics control. Also, blood glucose levels of the diabetic rats treated with aqueous extract showed decrease of 78.79% on the first day and the effect remains roughly constant during 3 week. Both extracts also declined significantly biochemical parameters (20.77%-49.00%). The control in the loss of body weight was observed in treated diabetic rats as compared to diabetic controls.

CONCLUSIONS

These results demonstrated significant antidiabetic effects and showed that serum cholesterol and serum triglycerides levels were decreased, significantly, consequently this plant might be of value in diabetes treatment.