Toxic Fat Cells Responsible for Metabolic Syndrome and Other Diseases

Researchers have discovered biological indicators that help explain why some obese people develop chronic diseases, such as diabetes and heart disease, and others do not. The researchers took a novel approach of looking specifically at the body fat of people with metabolic syndrome -- a condition characterized by increased blood pressure, high fasting blood sugar levels, excess abdominal fat, and abnormal cholesterol levels.

Results showed that the subcutaneous adipose tissue of patients with metabolic syndrome showed increased macrophage recruitment; this appears to contribute to the increased cellular inflammation that leads to increased levels of adipokines and other biomarkers that are correlated with both insulin resistance and chronic inflammation.

The conclusion of this study shows that not all obesity is the same; some body fat may actually be "toxic," whereas other adipose tissue is not as dangerous.

This study, "Adipose Tissue Dysregulation in Patients with Metabolic Syndrome," was published online August 24, 2011 in the Journal of Clinical Endocrinology & Metabolism (1). An online summary of the study is also available (2).

Although we don't know for certain if similar toxic forms of adipose tissue are present in dogs and cats with obesity, it is likely.

As in man, obesity in dogs and cats is characterized by an expansion of white adipose tissue mass that can lead to adverse health effects, such as decreased longevity, diabetes mellitus, orthopedic and respiratory disease, and neoplasia. Once thought a passive fuel depot, adipose tissue in our companion animals is now recognized as an active endocrine organ that communicates with the brain and peripheral tissues by secreting a wide range of hormones and protein factors, collectively termed adipokines (3-6). Examples include leptin, adiponectin, cytokines (tumor necrosis factor-alpha, interleukin-6), chemokines, acute phase proteins, homeostatic and hemodynamic factors,and neurotrophins. Adipokines can influence various body systems, and perturbation of normal endocrine function is thought central to the development of many associated conditions (3-6).

More than half of our dogs and cats are overweight, and obesity continues to emerge as a leading cause of preventable disease and death in dogs and cats.

References:

1. Bremer AA, Devaraj S, Afify A, Jialal I. Adipose tissue dysregulation in patients with metabolic syndrome. The Journal of Clinical Endocrinology & Metabolism 2011 jc.2011-1577 DOI: 10.1210/jc.2011-1577
2. Why Only Some Obese People Develop Chronic Diseases: Disease-Causing Fat Cells Found in Those With Metabolic Syndrome. ScienceDaily; August 24, 2011.
3. German AJ, Hervera M, Hunter L, et al. Improvement in insulin resistance and reduction in plasma inflammatory adipokines after weight loss in obese dogs. Domestic Animal Endocrinology 2009;37:214-226.
4. German AJ, Ryan VH, German AC, et al. Obesity, its associated disorders and the role of inflammatory adipokines in companion animals. Veterinary Journal 2010;185:4-9.
5. Lusby AL, Kirk CA, Bartges JW. The role of key adipokines in obesity and insulin resistance in cats. Journal of the American Veterinary Medical Association 2009;235:518-522.
6. Ryan VH, German AJ, Wood IS, et al. Adipokine expression and secretion by canine adipocytes: Stimulation of inflammatory adipokine production by LPS and TNFalpha. Pflugers Archivive 2010;460:603-616.