Obesity Discussion Forums - View Single Post - Macrophage-secreted factors induce adipocyte inflammation and insulin resistance

Obesity Discussion · 02-13-06, 07:52 PM

Authors: Permana, Paska A
Menge, Christopher
Reaven, Peter D.
Source: Biochemical & Biophysical Research Communications; Mar2006, Vol. 341 Issue 2, p507-514, 8p

Macrophage infiltration into adipose tissue increases with obesity, a condition associated with low-grade inflammation and insulin resistance. We investigated the direct effects of macrophage-secreted factors on adipocyte inflammation and insulin resistance. 3T3-L1 adipocytes incubated with media conditioned by RAW264.7 macrophages (RAW-CM) showed dramatically increased transcription of several inflammation-related genes, greater nuclear factor kappa B (NF-?B) activity, and enhanced binding of U937 monocytes. All of these effects were prevented by co-incubation with pyrrolidinedithiocarbamate, an NF-?B inhibitor. Adipocytes incubated with RAW-CM also released more non-esterified fatty acids and this increased lipolysis was not suppressed by insulin. In addition, RAW-CM treatment decreased insulin-stimulated glucose uptake in adipocytes. Taken together, these results indicate that macrophage-secreted factors induce inflammatory responses and reduce insulin responsiveness in adipocytes. These effects of macrophage-secreted factors on adipocytes may contribute significantly to the systemic inflammation and insulin resistance associated with obesity.

Author Affiliations:
Research Service, Carl T. Hayden Veterans Affairs Medical Center, Phoenix, AZ 85012-1892, USA
Department of Medicine, Section of Metabolism, Endocrinology and Nutrition, Carl T. Hayden Veterans Affairs Medical Center, Phoenix, AZ 85012-1892, USA

02-13-06, 07:52 PM	#1 (permalink)
Obesity Discussion Administrator Join Date: Jan 2005 Location: Phoenix, AZ Posts: 7,799 Weight Statistics 8/1/2006 Start Date: 185 lb Start Weight: 152 lb Current Weight: 155 lb Goal Weight: -33 lb Weight Loss: 5/1/2007 Goal Date:	Macrophage-secreted factors induce adipocyte inflammation and insulin resistance Authors: Permana, Paska A Menge, Christopher Reaven, Peter D. Source: Biochemical & Biophysical Research Communications; Mar2006, Vol. 341 Issue 2, p507-514, 8p Macrophage infiltration into adipose tissue increases with obesity, a condition associated with low-grade inflammation and insulin resistance. We investigated the direct effects of macrophage-secreted factors on adipocyte inflammation and insulin resistance. 3T3-L1 adipocytes incubated with media conditioned by RAW264.7 macrophages (RAW-CM) showed dramatically increased transcription of several inflammation-related genes, greater nuclear factor kappa B (NF-?B) activity, and enhanced binding of U937 monocytes. All of these effects were prevented by co-incubation with pyrrolidinedithiocarbamate, an NF-?B inhibitor. Adipocytes incubated with RAW-CM also released more non-esterified fatty acids and this increased lipolysis was not suppressed by insulin. In addition, RAW-CM treatment decreased insulin-stimulated glucose uptake in adipocytes. Taken together, these results indicate that macrophage-secreted factors induce inflammatory responses and reduce insulin responsiveness in adipocytes. These effects of macrophage-secreted factors on adipocytes may contribute significantly to the systemic inflammation and insulin resistance associated with obesity. Author Affiliations: Research Service, Carl T. Hayden Veterans Affairs Medical Center, Phoenix, AZ 85012-1892, USA Department of Medicine, Section of Metabolism, Endocrinology and Nutrition, Carl T. Hayden Veterans Affairs Medical Center, Phoenix, AZ 85012-1892, USA __________________