GLP-1 Therapy: The Role of IL-6 Signaling and Adipose Tissue Remodeling in Metabolic Response

This project investigates the anti-obesity mechanisms of glucagon-like peptide-1 (GLP-1) analogs, which are used in the treatment of human obesity and diabetes mellitus. The investigators will test if GLP-1 induces secretion of interleukin-6 (IL-6), a cytokine that may collaborate with GLP-1 analogs to induce the formation of brown fat, which has anti-diabetic properties. The results will guide future obesity and diabetes mellitus therapies.

Study Overview

• Status: Completed
• Conditions: Glucose Intolerance; Drug Effect; Overweight and Obesity; Adiposity
• Intervention / Treatment: Drug: Cyanocobalamin; Drug: Dulaglutide

Detailed Description

Incretins, the analogs of glucagon-like peptide-1 (GLP-1), improve glucose control in type 2 diabetes mellitus and counteract obesity through mechanisms that are not completely understood. The investigators' preliminary data show that, in prediabetic human subjects and mice, GLP-1 analog therapy induces an increase in plasma interleukin-6 (IL-6), a cytokine activating signal transducer and activator of transcription 3 (STAT3) signaling, which induces brown (beige) adipocyte differentiation in adipose tissue (AT). The investigators discovered that plasma IL-6 induction occurs through GLP-1 receptor (GLP-1R) stimulation in leukocytes. Interestingly, studies in rodents indicate that GLP-1 / GLP-1R signaling also induces AT beiging. Based on these observations, the investigators hypothesize that incretins induce AT browning in part via transient IL-6 / IL-6 receptor (IL-6R) / STAT3 signaling. The primary objective is to further elucidate the role of IL-6 and GLP-1 signaling in mediating beneficial metabolic effects of incretin therapy. Studies will be paralleled in a human clinical trial, a human cell culture model, and a mouse diet-induced obesity model. GLP-1 analog therapy combined with an IL-6 blocking antibody will be used. Specific Aim 1 is to (A) investigate IL-6 induction / downstream STAT3 signaling and AT browning upon incretin therapy in prediabetic human subjects; and (B) validate mice as a model to study incretin-induced IL-6 signaling as a mediator of AT browning. Specific Aim 2 is to (A) investigate if GLP-1 analog effects on beige adipogenesis depend on IL-6 signaling in human adipocyte progenitors; and (B) investigate if GLP-1 analog effects on beige adipogenesis depend on IL-6 signaling in mice. It is expected that 1) GLP-1 analog signaling via GLP-1R induces IL-6 secretion by leukocytes, and 2) GLP-1 analog therapy induces adipose tissue browning via both direct GLP-1 / GLP-1R signaling and indirect incretin-induced IL-6 / IL-6R / STAT3 signaling. The results of this novel study will give critical insights on the anti-obesity mechanisms of GLP-1 analogs and serve as the basis for developing more targeted therapies for diabetes and obesity. Understanding the anti-diabetic IL-6 effects will also be important for interpreting the results of IL-6 blockade, a therapeutic approach for patients with diabetes and other inflammatory conditions, which may need to be re-considered.

• Study Type: Interventional
• Enrollment (Actual): 23
• Phase: Phase 4

Contacts and Locations

Study Locations

• United States
  • Texas
    • Houston, Texas, United States, 77030
      • The University of Texas Health Science Center at Houston

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 50 years (Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion criteria:

1. Men and women, ages 18-50 years
2. Diagnosis of Prediabetes - defined as either impaired fasting glucose (fasting glucose of 100-125 mg/dL), impaired glucose tolerance (2-hour postprandial blood glucose of 140-199 mg/dL after 75-gram oral glucose challenge), and/or a hemoglobin A1C ranging from 5.5% to 6.4%.
3. BMI ≤ 35 kg/m2
4. Women of childbearing age must agree to use an acceptable method of pregnancy prevention (barrier methods, abstinence, oral contraception, vaginal rings, long-acting reversible contraceptives, or surgical sterilization) for the duration of the study
5. Patients must have the following laboratory values: Hematocrit ≥ 33 vol%, estimated glomerular filtration rate ≥ 60 mL/min per 1.73 m2, AST (SGOT) < 2.5 times ULN, ALT (SGPT) < 2.5 times ULN, alkaline phosphatase < 2.5 times ULN
6. If patients are receiving antihypertensive medications (other than beta blockers) and/or lipid-lowering medications, they must remain on stable doses for the duration of the study.
7. If patients are receiving NSAIDs or antioxidant vitamins, these must be discontinued one week prior to study initiation and cannot be restarted during the study.
8. If patient takes thyroid medications, these must be dosed to control hypo- or hyperthyroidism.

Exclusion Criteria:

1. History of Type 1 or Type 2 diabetes mellitus
2. Pregnant or breastfeeding women
3. Medications: Beta blockers, corticosteroids, monoamine oxidase inhibitors, diabetes medications (including incretin mimetics and thiazolidinediones), and/or immunosuppressive therapy over the last 2 months.
4. Uncontrolled hypo- or hyperthyroidism
5. Current tobacco use
6. Active malignancy
7. History of clinically significant cardiac, hepatic, or renal disease.
8. History of any serious hypersensitivity reaction to study medications, any other incretin mimetic, any other formulation of supplemental vitamin B12, and/or cobalt
9. Personal or family history of Leber hereditary optic nerve atrophy
10. Prisoners or subjects who are involuntarily incarcerated
11. Compulsorily detention for treatment of either a psychiatric or physical (e.g., infectious disease) illness
12. Prior history of pancreatitis, medullary thyroid cancer, or multiple endocrine neoplasia type 2 (MEN 2)
13. Serum vitamin B12 level above the upper limit of assay detection

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Cyanocobalamin, then Dulaglutide; Participants first received Cyanocobalamin (vitamin B12) 1000 mcg subcutaneous weekly for 6 weeks. After a washout period of 3 weeks, they then received Dulaglutide 0.75 mg subcutaneous weekly for 2 weeks, followed by 1.5 mg subcutaneous weekly for 4 weeks	Drug: Cyanocobalamin; Cyanocobalamin (vitamin B12) 1000 mcg subcutaneous weekly for 6 weeks.; Other Names: Vitamin B12; Drug: Dulaglutide; Dulaglutide 0.75 mg subcutaneous weekly for 2 weeks, followed by 1.5 mg subcutaneous weekly for 4 weeks; Other Names: Trulicity
Experimental: Dulaglutide, then Cyanocobalamin; Participants first received Dulaglutide 0.75 mg subcutaneous weekly for 2 weeks, followed by 1.5 mg subcutaneous weekly for 4 weeks. After a washout period of of 3 weeks, they then Cyanocobalamin (vitamin B12) 1000 mcg subcutaneous weekly for 6 weeks.	Drug: Cyanocobalamin; Cyanocobalamin (vitamin B12) 1000 mcg subcutaneous weekly for 6 weeks.; Other Names: Vitamin B12; Drug: Dulaglutide; Dulaglutide 0.75 mg subcutaneous weekly for 2 weeks, followed by 1.5 mg subcutaneous weekly for 4 weeks; Other Names: Trulicity

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cytokine Interleukin-6 (IL-6) Messenger Ribonucleic Acid (mRNA) Level (From Adipose Tissue)	natural log transformed data is reported	6 weeks after start of each intervention
Uncoupling Protein 1 (UCP1) Messenger Ribonucleic Acid (mRNA) Level (From Adipose Tissue)	Uncoupling protein 1 (UCP1) is a marker of beige/brown fat. natural log transformed data is reported	6 weeks after start of each intervention
Signal Transducer and Activator of Transcription 3 (STAT3) Band Intensity/Western Blot (From Adipose Tissue)	signaling intermediary with interleukin-6	6 weeks after start of each intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
PR Domain Containing 16 (PRDM16) Messenger Ribonucleic Acid (mRNA) Level ((From Adipose Tissue)	PR domain containing 16 (PRDM16) is a marker of beige/brown fat. natural log transformed data is reported.	6 weeks after start of each intervention
Nicotinamide Adenine Dinucleotide Dehydrogenase (Ubiquinone) Iron-sulfur protein3 (NDUFS3) (From Adipose Tissue)	marker of beige/brown fat	6 weeks after start of each intervention
Beta1-adrenoceptor (ADRB1) (From Adipose Tissue)	marker of beige/brown fat	6 weeks after start of each intervention
Beta2-adrenoceptor (ADRB2) (From Adipose Tissue)	marker of beige/brown fat	6 weeks after start of each intervention
Beta3-adrenoceptor (ADRB3) (From Adipose Tissue)	marker of beige/brown fat	6 weeks after start of each intervention
Nuclear Factor Kappa B (NfKappaB) p65 Band Intensity/Western Blot (From Peripheral Blood Mononuclear Cells)	signaling intermediary with interleukin-6	6 weeks after start of each intervention
Interleukin-6 (IL-6) mRNA (From Peripheral Blood Mononuclear Cells)	cytokine	6 weeks after start of each intervention
IL-6 (From Peripheral Blood Mononuclear Cells)	cytokine	6 weeks after start of each intervention
Suppressor of Cytokine Signaling 3 (SOCS3) Band Intensity/Western Blot (From Peripheral Blood Mononuclear Cells)	signaling intermediary with interleukin-6	6 weeks after start of each intervention
Cytokine IL-6 Level (From Plasma)	natural log transformed data is reported. The "Measure Type" indicated as "Mean" actually refers to a "Adjusted Mean." Mean was adjusted for meteorological season. The meteorological season (i.e., spring, summer, fall, and winter) was adjusted for in the multivariable analysis as a potential confounding factor, since imbalances in ambient temperature between study arms could affect the findings.	6 weeks after start of each intervention
Free Fatty Acids Level (From Plasma)	Free fatty acids level is a marker for insulin resistance. natural log transformed data is reported The "Measure Type" indicated as "Mean" actually refers to a "Adjusted Mean." Mean was adjusted for meteorological season. The meteorological season (i.e., spring, summer, fall, and winter) was adjusted for in the multivariable analysis as a potential confounding factor, since imbalances in ambient temperature between study arms could affect the findings.	6 weeks after start of each intervention
Insulin Level (From Plasma)	Insulin Level is a marker of insulin resistance. natural log transformed data is reported. The "Measure Type" indicated as "Mean" actually refers to a "Adjusted Mean." Mean was adjusted for meteorological season. The meteorological season (i.e., spring, summer, fall, and winter) was adjusted for in the multivariable analysis as a potential confounding factor, since imbalances in ambient temperature between study arms could affect the findings.	6 weeks after start of each intervention
Glucose Level (From Plasma)	Glucose Level is a marker of insulin resistance. The "Measure Type" indicated as "Mean" actually refers to a "Adjusted Mean." Mean was adjusted for meteorological season. The meteorological season (i.e., spring, summer, fall, and winter) was adjusted for in the multivariable analysis as a potential confounding factor, since imbalances in ambient temperature between study arms could affect the findings.	6 weeks after start of each intervention
Tumor Necrosis Factor - Alpha (From Plasma)	natural log transformed data is reported. The "Measure Type" indicated as "Mean" actually refers to a "Adjusted Mean." Mean was adjusted for meteorological season. The meteorological season (i.e., spring, summer, fall, and winter) was adjusted for in the multivariable analysis as a potential confounding factor, since imbalances in ambient temperature between study arms could affect the findings.	6 weeks after start of each intervention
Interleukin-4 (From Plasma)	cytokine	6 weeks after start of each intervention
Interleukin-10 (From Plasma)	cytokine	6 weeks after start of each intervention
Interleukin-11 (From Plasma)	cytokine	6 weeks after start of each intervention
Interleukin-13 (From Plasma)	cytokine	6 weeks after start of each intervention
Glucagon-like Peptide-1 (From Plasma)	The "Measure Type" indicated as "Mean" actually refers to a "Adjusted Mean." Mean was adjusted for meteorological season. The meteorological season (i.e., spring, summer, fall, and winter) was adjusted for in the multivariable analysis as a potential confounding factor, since imbalances in ambient temperature between study arms could affect the findings.	6 weeks after start of each intervention
Homeostatic Model Assessment of Insulin Resistance (HOMA-IR)	Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) is a marker of insulin resistance, calculated according to the formula: fasting insulin (mU/mL) x fasting glucose (mmol/L)/22.5 The "Measure Type" indicated as "Mean" actually refers to a "Adjusted Mean." Mean was adjusted for meteorological season. The meteorological season (i.e., spring, summer, fall, and winter) was adjusted for in the multivariable analysis as a potential confounding factor, since imbalances in ambient temperature between study arms could affect the findings.	6 weeks after start of each intervention
Fat Browning Measured as Standard Uptake Value (From Positron Emission Tomography - Computed Tomography (PET-CT) Reading)	The "Measure Type" indicated as "Mean" actually refers to a "Adjusted Mean." Mean was adjusted for meteorological season. The meteorological season (i.e., spring, summer, fall, and winter) was adjusted for in the multivariable analysis as a potential confounding factor, since imbalances in ambient temperature between study arms could affect the findings.	6 weeks after start of each intervention
Oroboros Oxygen Consumption	measure of oxygen consumption	6 weeks after start of each intervention

Collaborators and Investigators

• Sponsor: The University of Texas Health Science Center, Houston
• Collaborators: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
• Investigators: Principal Investigator: Absalon D Gutierrez, MD, The University of Texas Health Science Center at Houston, Dept. of Medicine

Study record dates

Study Major Dates

• Study Start (Actual): May 15, 2020
• Primary Completion (Actual): October 6, 2023
• Study Completion (Actual): October 6, 2023

Study Registration Dates

• First Submitted: May 6, 2020
• First Submitted That Met QC Criteria: May 11, 2020
• First Posted (Actual): May 13, 2020

Study Record Updates

• Last Update Posted (Actual): December 5, 2024
• Last Update Submitted That Met QC Criteria: November 13, 2024
• Last Verified: November 1, 2024

More Information

Terms related to this study

• Keywords: GLP-1; IL-6; prediabetes; adipose tissue; brown fat
• Additional Relevant MeSH Terms: Nutrition Disorders; Metabolic Diseases; Overnutrition; Body Weight; Glucose Metabolism Disorders; Hyperglycemia; Overweight; Glucose Intolerance; Glucagon-Like Peptide-1 Receptor Agonists; Physiological Effects of Drugs; Hypoglycemic Agents; Micronutrients; Vitamin B Complex; Vitamins; Hematinics; Vitamin B 12; Hydroxocobalamin; Dulaglutide
• Other Study ID Numbers: HSC-MS-19-0787; R21DK122234 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: We will share all participant data (which will be deidentified) regarding our plasma samples, subcutaneous adipose tissue samples, and peripheral blood mononuclear cells. A study protocol and statistical analysis plan will be available as specified per policy of clinicaltrials.gov.
• IPD Sharing Time Frame: Data will become available one year after the primary completion date of the clinical trial, or 6 months post-publication, or 18 months after award end date - whichever comes first. Data will then be available indefinitely.
• IPD Sharing Access Criteria: Anyone can access the data via clinicaltrials.gov. If applicable, data will also be shared via the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) Information Network.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No