Overweight fat cells make people sick

Overweight: Membranes of fat cells determine health risks

12/06/2011

Heavy obesity, that is, obesity, can have serious health consequences. A Finnish twin study analyzed the effects of body fat on health, with the main focus on the so-called metabolic syndrome.

Overweight is considered a crucial risk factor for a variety of diseases. Particularly dangerous for overweight people is the so-called metabolic syndrome, which is characterized by obesity, high blood pressure (hypertension), insulin resistance (episode diabetes type II) and altered blood lipid levels (dyslipidemia). Researchers from the VTT Technical Research Center of Finland have now deciphered the mechanism of action, which promotes an increased body fat percentage of the occurrence of the metabolic syndrome.

In the long-term study of 21 Finnish twin pairs, one of which was overweight, researchers at the VTT Technical Research Center of Finland analyzed the effects of body fat on health. The connection with the occurrence of the metabolic syndrome formed a focal point of the investigation. The researchers found that the individually variable adaptive capacity of the fat cell membrane plays a key role in overweight and obesity-related health impairments. In a next step, the researchers now hope to be able to influence the adaptability of the membrane of the fat cells, because they have discovered in their investigations, a gene that causes the transformation of the cell membrane.

Different membrane structure in excess weight and nominal weight
According to the researchers of the VTT Technical Research Center of Finland, changes in fat cells are the basis for the negative health consequences of overweight and obesity. In their study of 21 pairs of Finnish twins, VTT scientists have discovered how the altered fat cells can lead to serious health problems. One focus of the study was the connection with the metabolic syndrome, which is regarded as the main risk factor for cardiovascular diseases and heart attacks in Germany. Since the participating identical twins were equipped with the same genetic make-up, genetic influences could be largely excluded. The researchers found that the membrane structure of fat cells in overweight twins was significantly different compared to their leaner siblings. While the diet of overweight twins contained significantly lower levels of polyunsaturated fatty acids than their siblings, the proportion of unsaturated fatty acids in their fat tissue was unexpectedly much higher than that of the slimmer study participants, the scientists report in the online edition of the journal „PLoS Biology“.

Cell membranes in obese people are restructured
Because the identified polyunsaturated fatty acids have a significant impact on the membrane structure of fat cells and help to increase their elasticity and permeability, the researchers hypothesize, „that it is a coping mechanism“, with the help of which the functionality of the cell membrane should be maintained even with extreme expansion of the cells. Although the membrane structure of the overweight and slender twins was fundamentally different, the researchers at VTT were unable to detect any differences in their functional capacity. Due to the increased proportion of unsaturated fatty acids in the cell membranes, these also retained their function in the obese, explained the experts. But complementary analyzes show that the adaptability of the cells can only be guaranteed to a certain point and that the functionality of the membrane collapses at the latest with the onset of the metabolic syndrome, report Matej Orešič from the VTT Technical Research Center of Finland and colleagues.

Omega-6 fatty acids promote the appearance of inflammation
Although none of the examined overweight twins had already developed a metabolic syndrome, but the excessive or incorrect food intake increased fat deposits on the legs, hips, abdomen and buttocks - excess nutrients were stored in the fat cells of the body. Among other things, the lipids contained in the cell membranes determine the permeability and the adaptability of the membrane. The higher the proportion of polyunsaturated fatty acids in the membrane structure, the higher the permeability. According to the researchers of the VTT, however, a distinction must be made between the different unsaturated fatty acids. For example, with the help of the increased omega-6 fatty acid content in the cell membranes of the overweight, the functionality can be maintained, but the omega-6 fatty acids in turn cause a significant proportion of the negative health consequences of the overweight, report the researchers of the VTT. Unlike omega-3 fatty acids in the cell membranes of normal-weight subjects, omega-6 fatty acids in the human body act as messengers that trigger a defense reaction. This favors inflammation in the body - especially in adipose tissue - which in turn could cause further health problems, write Matej Orešič and colleagues.

Individual differences in the membranes of fat cells
According to the researchers, there are significant individual differences in the response of fat cells to increased food intake. „We think it likely that the cell threshold is genetically determined“, explained the experts of the VTT. Both the restructuring of the cell membrane and the maximum storage capacity of the fat cells are different from person to person, which also explains why some obese people have significant health problems, while others live relatively carefree with their fat pads. Once the fat cell membranes have reached their capacity limits, the fat cells can not absorb additional nutrients and the excess fat is stored in other organs such as muscles, liver or pancreas. Lipid metabolism disorders are one of the consequences and those affected threaten the long term metabolic syndrome, the experts report. According to statements by Kirsi H. Pietiläinen (Obesity Research Unit, Helsinki University Central Hospital), Antonio Vidal-Puig (University of Cambridge) and Matej Orešič numerous health risks - especially in the field of cardiovascular diseases.

Prevent restructuring of the fat cell membrane
But even before the membranes of fat cells reach their limits, a restructuring on the level of unsaturated fatty acids appears to take place. This will allow the international research team to Matej OrešAccording to ič, although the functionality of the membrane is maintained despite considerable expansion, the increased omega-6 fatty acid concentration in turn promotes the occurrence of inflammation - especially in the fatty tissue of the human organism. The „coping mechanism “ thus brings a serious disadvantage: „There are more and more inflammations“, which, in turn, are considered to be a major factor in the development of the metabolic syndrome, Matej Ore explainedšIC. The researchers therefore believe that maintaining a healthy membrane structure of fat cells is critical to minimizing the health risks of obesity. Even in obese people, the cell membrane should contain predominantly omega-3 fatty acids instead of the health-threatening omega-6 fatty acid. What at first glance seems hardly influenceable, may soon be feasible, according to the VTT researchers. Because Matej OrešAs part of their study, ič and colleagues were able to identify a gene that could bring about a restructuring of the cell membrane. „The big news is that we can manipulate the process“, the conclusion of the international research group in the online edition of the journal „PLoS Biology“. (Fp)

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Gerd Altmann / Dieter Petereit, Pixelio.de