Adiposopathy - Pathophysiology - Anatomy

Anatomy

Diseased fat tissue surrounding various organs can cause illness, such as fat surrounding the heart, muscle, vessels, eyes, and bone. Some have suggested that diseased fat tissue surrounding the heart and vessels can contribute to inflammation and plaque rupture. Although not as well recognized, even the so-called “protective” subcutaneous fat tissue has the potential to be “sick” and contribute to metabolic disease. A prime example would be subcutaneous fat tissue found in the abdominal region. Accumulation of fat tissue in this region may have hormonal and immune activity, and thus the potential to cause metabolic disease, between that of visceral fat tissue and other areas of subcutaneous fat tissue.

However, other subcutaneous fat tissues also might contribute to metabolic disease, if the fat cells become too enlarged and “sick.” Admittedly, subcutaneous fat cells typically are larger, and capable of storing more fat when needed. However, subcutaneous fat tissue represents the largest proportion of fat tissue in the body, and is the major source of leptin.

One potentially unfavorable effect of leptin is to increase blood pressure, as observed in animals. In humans, the observation of leptin-induced hypertension is not as yet conclusive. But to the extent that leptin may increase blood pressure, then the increase in leptin with subcutaneous fat cells (particularly when they become enlarged) could hardly be characterized as “protective.”

Other potentially detrimental effects of enlarged subcutaneous fat tissue relate to free fatty acids. During fasting, the body can obtain energy through the release of free fatty acids from the triglycerides in fat cells. The fatty acids thus become available for release into the blood. If too high a concentration of certain fatty acids accumulates in the blood because of sick fat tissue, and the body is unable to recruit more healthy fat cells, then existing healthy fat cells become engorged (and thus also sick). The result is that blood fatty acid concentrations increase to levels toxic to tissues such as liver, muscle, and pancreas, and lead to a range of pathological metabolic conditions.

There are grounds for suspicion that sick abdominal fat tissue may produce factors that cause subcutaneous fat tissue to also become “sick” and further contribute to metabolic diseases.

In summary, although abdominal or visceral fat tissue is best described to contribute to metabolic disease, abdominal fat is by no means the only fat tissue depot that has the potential to become “sick” and capable of contributing to metabolic ill health.