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

Phase 4

Completed

Conditions: Glucose Intolerance
Overweight and Obesity
Drug Effect
Adiposity

Interventions: Drug: Cyanocobalamin
Drug: Dulaglutide

Registration Number: NCT04387201

Lead Sponsor: The University of Texas Health Science Center, Houston

Brief Summary: 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.

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.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 23

Inclusion Criteria

Not provided

Exclusion Criteria

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

Study & Design

Study Type: INTERVENTIONAL

Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Cyanocobalamin, then Dulaglutide	Cyanocobalamin	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
Cyanocobalamin, then Dulaglutide	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
Dulaglutide, then Cyanocobalamin	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.
Dulaglutide, then Cyanocobalamin	Dulaglutide	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.

Primary Outcome Measures

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

Secondary Outcome Measures

Name	Time	Method
IL-6 (From Peripheral Blood Mononuclear Cells)	6 weeks after start of each intervention	cytokine
PR Domain Containing 16 (PRDM16) Messenger Ribonucleic Acid (mRNA) Level ((From Adipose Tissue)	6 weeks after start of each intervention	PR domain containing 16 (PRDM16) is a marker of beige/brown fat. natural log transformed data is reported.
Nicotinamide Adenine Dinucleotide Dehydrogenase (Ubiquinone) Iron-sulfur protein3 (NDUFS3) (From Adipose Tissue)	6 weeks after start of each intervention	marker of beige/brown fat
Beta1-adrenoceptor (ADRB1) (From Adipose Tissue)	6 weeks after start of each intervention	marker of beige/brown fat
Beta2-adrenoceptor (ADRB2) (From Adipose Tissue)	6 weeks after start of each intervention	marker of beige/brown fat
Beta3-adrenoceptor (ADRB3) (From Adipose Tissue)	6 weeks after start of each intervention	marker of beige/brown fat
Nuclear Factor Kappa B (NfKappaB) p65 Band Intensity/Western Blot (From Peripheral Blood Mononuclear Cells)	6 weeks after start of each intervention	signaling intermediary with interleukin-6
Interleukin-6 (IL-6) mRNA (From Peripheral Blood Mononuclear Cells)	6 weeks after start of each intervention	cytokine
Suppressor of Cytokine Signaling 3 (SOCS3) Band Intensity/Western Blot (From Peripheral Blood Mononuclear Cells)	6 weeks after start of each intervention	signaling intermediary with interleukin-6
Cytokine IL-6 Level (From Plasma)	6 weeks after start of each intervention	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.
Free Fatty Acids Level (From Plasma)	6 weeks after start of each intervention	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.
Insulin Level (From Plasma)	6 weeks after start of each intervention	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.
Glucose Level (From Plasma)	6 weeks after start of each intervention	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.
Tumor Necrosis Factor - Alpha (From Plasma)	6 weeks after start of each intervention	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.
Interleukin-4 (From Plasma)	6 weeks after start of each intervention	cytokine
Interleukin-10 (From Plasma)	6 weeks after start of each intervention	cytokine
Interleukin-11 (From Plasma)	6 weeks after start of each intervention	cytokine
Interleukin-13 (From Plasma)	6 weeks after start of each intervention	cytokine
Glucagon-like Peptide-1 (From Plasma)	6 weeks after start of each intervention	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.
Homeostatic Model Assessment of Insulin Resistance (HOMA-IR)	6 weeks after start of each intervention	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.
Fat Browning Measured as Standard Uptake Value (From Positron Emission Tomography - Computed Tomography (PET-CT) Reading)	6 weeks after start of each intervention	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.
Oroboros Oxygen Consumption	6 weeks after start of each intervention	measure of oxygen consumption