Why Big Fat Cells May Cause Inflammation

Obesity is characterised by the accumulation of excess fat but we have long known that the same amount of excess fat can have very different health effects on different people.

While some individuals with a higher BMI may appear metabolically healthy, others are prone to develop type 2 diabetes, dysplipidemia and other metabolic complications.

One of the consistent findings from biopsy studies has been that metabolically healthy obese individuals tend to have smaller (but larger numbers of) fat cells than their less healthy counterparts.

More recently, large fat cells have been associated with adipose tissue inflammation, now believed to play an important role in the development of the metabolic complications.

However, how exactly large fat cells mediate or augment adipose tissue inflammation is not clear.

A study by Kirsi Pietiläinen and colleagues from the University of Helsinki, Finland, just published in PLoS Biology, suggests a possible role for alterations in adipocyte membrane composition as a mediator of tissue inflammation.

In their studies, Pietiläinen and colleagues performed lipidomic analyses of human adipose tissue in twin pairs discordant for obesity as well as severely obese individuals with and without metabolic disease.

Their findings suggest that as adipocytes increase in size, the composition of their lipid membrane phospholipid composition changes in a manner that may make these cells more prone to triggering inflammatory pathways.

Thus, normal membrane function (fluidity and integrity) is maintained in the expanding adipose tissue at the expense of increasing its vulnerability to inflammation.

The researchers also used complex simulations and cell culture experiments to validate their findings.

Importantly, as the authors point out, these findings may open doors to using pharmacological and/or nutritional changes to influence adipocyte cell membrane composition and to thereby attenuate or inhibit adipose tissue inflammation and its metabolic consequences.

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