Endotoxin & Cytokines. Do Protein Loss and Metabolic Effects Depend on Central Nervous System (CNS) Activation of Stress Hormones or on Local Mechanisms in Muscle and Fat?

Study Overview
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Brief Summary
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Main objective : The purpose of this study is to prove that the effects of bacterial endotoxin and cytokine TNF-α, on protein loss, fatty acid release, and glucose metabolism depend on two mechanisms: Direct local effects in muscle tissue. Activation of the hypothalamo-pituitary axis and a stress-hormone response Study protocols: Acute metabolic effects of TNF-α(Beromun, Boehringer-Ingelheim Germany) vs placebo perfused into the femoral artery of the leg in 8 healthy subjects. Acute metabolic effects of placebo(saline) endotoxin(US standard reference E.Coli, endotoxin) TNF-α(Beromun, Boehringer-Ingelheim Germany) given systemically in 8 patients with hypopituitarism(to block stress hormone release) and in 8 healthy subjects all studied thrice.

Detailed Description
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PURPOSE: Knowledge about the effects of bacterial endotoxin and cytokines (and inflammation in general) in humans on protein, glucose and lipid metabolism and intracellular signalling in muscle and fat is sporadic and it is uncertain whether endotoxin and cytokines act directly in fat and muscle tissue or indirectly via central nervous system (CNS) mediated stress hormone release. The investigators hypothesize that the metabolic effects of endotoxin and cytokine TNF-α, including protein loss, fatty acid release and decreased glucose uptake depend on two mechanisms: Direct local effects in muscle tissue (Study protocol 1) Activation of the hypothalamo-pituitary axis and generalized stress hormone response (Study protocol 2) METHODOLOGY: Study protocol 1: Acute metabolic effects of TNF-α (Beromun, Boehringer-Ingelheim, Germany) versus placebo perfused into the femoral artery of the leg in 8 healthy subjects, studied once. Femoral vein sampling allows assessment of local metabolic events in the leg. The vessels were cannulated using the Seldinger technique. Each study comprises a 3 hour basal period and a 3 hour Hyperinsulinemic-Euglycemic Clamp. Muscle biopsies were obtained simultaneously from both lateral vastus muscles. Study protocol 2: Acute metabolic effects of (i)placebo (saline), (ii)endotoxin (US standard reference E.Coli, endotoxin) and (iii)TNF-α (Beromun, Boehringer-Ingelheim, Germany) given systemically intravenously (i.v.) in 8 patients with hypopituitarism (to block stress hormone release) and in 8 healthy subjects all studied thrice. Every study comprises a 4 hour basal period and a 2 hour Hyperinsulinemic-Euglycemic Clamp. Muscle and fat biopsies were obtained. Study protocol 1 and Study protocol 2: Assays: Mass spectrometry (15N-phenylalanine, 13C-urea), 3H-glucose, 3H-palmitate quantification, hormone and metabolite analysis, cytokine assays, intracellular signaling.

Official Title
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Endotoxin & Cytokines. Do Protein Loss and Metabolic Effects Depend on CNS Activation of Stress Hormones or on Local Mechanisms in Muscle and Fat?

Conditions
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Inflammation, Glucose Metabolism Disorders

Intervention / Treatment
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* Biological: TNF-alpha
* Biological: Endotoxin


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria 1. group: Male 19 < BMI < 28 18 ≤ Age ≤ 50 Healthy Inclusion Criteria 2. group: Male 20 < BMI < 30 Age > 25 Healthy Exclusion Criteria: Diseases Allergy

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: TNF-α<br>Beromun, Boehringer-Ingelheim, Germany | Biological: TNF-alpha<br>* Study protocol 1: 6 ng/kg/h intraarterial Study protocol 2: 18 ng/kg/h intravenous<br>* Other names: Beromun, Boehringer-Ingelheim, Germany;|
| Experimental: Endotoxin<br> | Biological: Endotoxin<br>* Study protocol 2:0,075 ng/kg/h intravenous<br>* Other names: E. coli endotoxin, US standard;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Acute metabolic effects of endotoxin and cytokine TNF-α (Study 2) | During a basal period. Acute metabolic effects: Glucose metabolism was quantified with raw arterio-venous differences and 3H3-Glucose tracer. Lactate was quantified with raw arterio-venous differences. Lipid metabolism was quantified with [9,10-3H]-Palmitate tracer and amino acid metabolism with 15N-Phenylalanine tracer and 13C-Urea tracer. | 2 hours | 
| Acute metabolic effects of endotoxin and cytokine TNF-α (Study 2) | During a hyperinsulinaemic euglycaemic clamp. Acute metabolic effects: Glucose metabolism was quantified with raw arterio-venous differences and 3H3-Glucose tracer. Lactate was quantified with raw arterio-venous differences. Lipid metabolism was quantified with [9,10-3H]-Palmitate tracer and amino acid metabolism with 15N-Phenylalanine tracer and 13C-Urea tracer. | 4 hours | 
| Acute metabolic effects of cytokine TNF-α (Study 1) | During a basal period. Acute metabolic effects: Glucose and lactate were quantified with raw arterio-venous differences; lipid metabolism was quantified with [9,10-3H]-palmitate and amino acid metabolism with 15N-phenylalanine. | 3 hours | 
| Acute metabolic effects of cytokine TNF-α (Study 1) | During a hyperinsulinaemic euglycaemic clamp. Acute metabolic effects: Glucose and lactate were quantified with raw arterio-venous differences; lipid metabolism was quantified with [9,10-3H]-palmitate and amino acid metabolism with 15N-phenylalanine. | 3 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Intracellular insulin signaling, growth hormone signalling and inflammatory signalling pathways. | Musle and fat biopsies during a basal period (120 min. from the beginning of a basal period) | 120 min. | 
| Intracellular insulin signaling, growth hormone signalling and inflammatory signalling pathways. | Musle and fat biopsies during a hyperinsulinaemic euglycaemic clamp (30 min. from the beginning of clamp) | 30 min. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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LPS, Endotoxin, TNF-α, insulin resistance, metabolism