Effects of Incretins on Human Platelet Function

Novel drugs for the treatment of patients with diabetes are of interest for cardiologists if they reduce the risk of cardiovascular events. However, as documented by the current discussion about the potential benefits of glitazones, high hopes can fail. Initial beneficial cardiovascular effects shown in proof-of-concept studies were muted by the apparent higher mortality in the metaanalysis of studies with rosiglitazone. The rapidly increasing use of GLP-1 analogues and DPP-4 (Dipeptidyl protease 4) inhibitors for the treatment of type 2 diabetes mellitus may be of major interest for the cardiologist. Potential beneficial actions on the cardiovascular system so far shown in animal experiments and small proof of concept studies may provide the rationale for using these drugs specifically in diabetic patients with secondary complications such as macrovascular disease or diabetic cardiomyopathy. Theoretically, these new therapies could also proof beneficial in patients with heart failure, independently of concomitant diabetes mellitus. However, many unanswered questions need to be addressed in the near future to extend the experimental findings to potential benefits of real life patients. In summary a new class of antidiabetic drugs, which could possibly directly influence cardiovascular effects of diabetes mellitus and thus possibly treat or even prevent life threatening complications has become available.

Then our working hypothesis was that incretins may have desirable cardiovascular outcomes through modulating platelet function. In order to test this hypothesis we propose to assess the presence of their specific receptors in isolated human platelets. In addition, we proposed to sudy the effect of the endogenous incretins (glucagon-like peptide 1 and gastric inhibitory peptide) on human platelet function isolated in a test tube.

Study Overview

• Status: Completed
• Conditions: Inhibition of Platelet Aggregation by Incretins
• Intervention / Treatment: Other: venous puncture

Detailed Description

Aims and Methods: The prevalence of Type 2 diabetes (T2D) continues to increase globally and brings with it a parallel increase in the associated cardiovascular disease complications. Correction of platelet hyperactivity holds promise for this high-risk population of T2D patients by contributing to restore normal hemostasis, which has lead to the search for new antiagregant drugs. Then, our aim was to study whether incretins may modulate platelet function; for this purpose platelets from healthy subjects who were not taken any medication were studied. Besides, normal mature megakaryocytes obtained by culture of human cord blood derived-CD34+ hematopoietic progenitor cells were also studied.

For platelet function studies, platelet aggregation was tested in the absence and presence of different concentrations (10-9 M to 10-5 M) of glucagon-like peptide-1,GLP1-(7-36)NH2, and glucose-dependent insulinotropic polypeptide (GIP) agonist by a turbidimetricassay. The effect of 300 mg/dLglucose added to the media was also evaluated. GLP1R (glucagon-like peptide 1 receptor) and GIPR (GIP receptor) mRNA expression was evaluated by Real Time PCR in platelet and megakaryocyte total mRNA. The putative presence of their proteins was assayed by western blot and flow cytometry in both samples.

• Study Type: Observational
• Enrollment (Actual): 20

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 21 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Healthy subjects

Description

Inclusion Criteria:

• Healthy blood donors

Exclusion Criteria:

• Diabetes
• Hypertension
• Morbid obesity
• Cardiovascular disease
• Hematological diseases and hyperlipidemia

Study Plan

How is the study designed?

Design Details

• Time Perspectives: Cross-Sectional

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
controls; Healthy volunteers will be asked to donor a 10-80 ml blood through a venous puncture	Other: venous puncture; Blood for in vitro studies will be drawn; Other Names: volunteers

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Expression of Glucagon Like Peptide -1 (GLP-1) and Gastric Inhibitory Peptide (GIP) Receptors in Normal Human Platelets	1.1 Measurement of GLP-1 and GIP receptors at the platelet RNA level by Real Time-PCR 1.2 GLP-1 and GIP receptors detection at the protein level: 1.2.1 Expression on platelet membrane by flow cytometry. 1.2.2 Detection in total platelet proteins by western-blot. Data of flow cytometry are provided below	Platelets drawn from a volunteer were evaluated 1 time (in 1-2 days)
Changes in Basal or Aggregant-induced Platelet Activation (With and Without Glucose Added to the Media, 200 mg/dl, 400 mg/dL) by GLP-1-(7-36)NH2 and Its Metabolite (GLP-1-(9-36)NH2)and a GIP Agonist at Different Concentrations.	1 Direct effect of GLP-1-(7-36)NH2 and its metabolite (GLP-1-(9-36)NH2) and GIP agonist on platelet aggregation, with and without preincubation at different glucose concentrations. 2. GLP-1-(7-36)NH2 and its metabolite (GLP-1-(9-36)NH2) and GIP agonist modulation (with and without 300 mg/dL glucose added to the media) of platelet activation and aggregation induced by classical platelet agonists such as ADP, collagen and bovine von Willebrand factor. Data points from various conditions were combined (averaged),	Platelets drawn from a volunteer will be evaluated 1 time (in 1-2 days)

Collaborators and Investigators

• Sponsor: National Council of Scientific and Technical Research, Argentina
• Collaborators: Merck Sharp & Dohme LLC
• Investigators: Principal Investigator: Carlos J Pirola, PhD, Unidad Ejecutora IDIM-CONICET

Study record dates

Study Major Dates

• Study Start: December 1, 2012
• Primary Completion (Actual): August 1, 2014
• Study Completion (Actual): August 1, 2014

Study Registration Dates

• First Submitted: August 1, 2011
• First Submitted That Met QC Criteria: August 2, 2011
• First Posted (Estimate): August 3, 2011

Study Record Updates

• Last Update Posted (Estimate): September 23, 2014
• Last Update Submitted That Met QC Criteria: September 19, 2014
• Last Verified: September 1, 2014

More Information

Terms related to this study

• Keywords: human; platelets; GIP; GLP1; aggregation
• Other Study ID Numbers: INC-PL-01