Human Adipocytes and the Composition of Plasma Lipoproteins: Linking Obesity with Type 2 Diabetes and Cardiovascular Disease

Maintaining energy homeostasis is one of the fundamental tasks of the body that has to be performed, and it is largely achieved through the control of blood glucose level. Thus normoglycemia is regulated through proper energy delivery to the energy-demanding tissues or storage in the adipose tissue through the lipoprotein compartment. The processes constitute a multitude of tightly regulated and highly tuned mechanisms, which is only partly understood and involved in all tissues. Nevertheless, the adipose tissue and in particular adipocytes together with the skeletal muscle and liver seems to be the most important organs for dealing with challenges to keep body energy and energy metabolic system in homeostasis. Although through most of mankind’s history, lack of energy was the main challenge in current societies excess intake of calories and especially fats and sugars as well as their main manifestation, and hyperglycemia-related diseases has become a serious problem. The situation is compounded by the increase of sedentary life-styles and the use of high level of tobacco (Cabrera de et al., 2007; Oh et al., 2005). Currently, 65% of the global population lives in countries where obesity kills more people than malnutrition (WHO - Global strategy on diet, physical activity and health, 2010). The metabolic diseases include obesity-induced metabolic syndrome, lipodystrophia, and type 2 diabetes mellitus (T2DM) represent an ever increasing challenge to health care. A guiding principle of this thesis is that many aspects of these diseases can be better understood through insight into the energy metabolism of the adipocytes as well as improved knowledge of the adipocytes and their production. Furthermore, I shall argue that the lipoprotein compartment is not only a mediator between the adipose compartment and the periphery with respect to the transport of energy-rich hydrophobic molecules, but also is an important transport modality for adipocyte-generated endrocrinological signals.