Lack of Oxygen Can Trigger Adipose Tissue Inflammation
Thursday, June 12, 2014
Lack of oxygen is a well known stressor for any living cell – this is of course also true for fat cells (adipocytes).
But lack of oxygen does not just occur when there is a problem with breathing or blood flow. Lack of oxygen (hypoxia) can also occur a the cellular level, when the cellular oxygen demand exceeds supply.
According to what may well be considered a “landmark” paper by Lee and colleagues, published in CELL, it appears that increased adipocyte oxygen consumption may be the key trigger of molecular changes that cause local inflammation and systemic insulin resistance commonly associated with obesity.
The paper reports on a series of animal studies with diet-induced obesity (through a high-fat diet), demonstrating that with increasing weight gain, adipocyte respiration in the mitochondria becomes “uncoupled” leading to a significant increase in oxygen consumption with relative hypoxia.
This uncoupling appears to be mediated through activation of adenine nucleotide translocase 2 (ANT2), an inner mitochondrial membrane protein, by saturated fatty acids.
The resulting hypoxia, in turn, activates the transcription factor HIF-1α, setting off a pro-inflammatory response which in turn leads to insulin resistance with an increased risk of diabetes.
The researcher also show that blocking either ANT2 or HIF-1α can prevent these events, thereby suggesting new pharmacological targets for alleviating the pro-inflammatory and metabolic consequences of obesity.
Obviously, there is always room for caution in extrapolating animal findings to humans, but this paper is likely to spawn a flurry of similar work in human fat cells.
As cellular hypoxia is more likely to occur the larger the fat cell, these studies also tie in the previous observations of a positive association between adipocyte cell size and metabolic abnormalities.
Certainly a topic we can expect to hear more of in the not too distant future.
@DrSharma
Edmonton, AB
Lee YS, Kim JW, Osborne O, Oh da Y, Sasik R, Schenk S, Chen A, Chung H, Murphy A, Watkins SM, Quehenberger O, Johnson RS, & Olefsky JM (2014). Increased Adipocyte O2 Consumption Triggers HIF-1α, Causing Inflammation and Insulin Resistance in Obesity. Cell, 157 (6), 1339-52 PMID: 24906151
Thursday, June 12, 2014
Inflammation is certainly an obvious sign of dis-ease. Dr. Sharma, in previous posts you have talked about sleep apnea and treatment. Certainly what we are learning about obesity is pointing to perhaps a revolution of how we treat obesity, but all dis-eases. We are a complex organism with multiple interconnected neuro, chemical, hormonal, and mechanical systems and mechanisms at play. It is so clear to me in my weight loss journey awaiting for surgery – is that I can’t just focus on one aspect of self or medical intervention…it is a wholistic effort and as you said we can’t draw conclusions based on animal studies.
Tuesday, July 15, 2014
Dr. Sharma,
Another studies (review Bluher 2013) suggest that HIF-1α is positive because it induces many pro angiogenic factors, that will improve the oxygenation of adipose tissue. Thus, this pro angiogenic factors will contribute for reduced of pro inflammatory factors like TNF-alpha. Reducing TNF-alpha contribute for reduce insulin resistance.
Regards
William.
Monday, July 6, 2020
This is late 2020, and I find that excessive wearing of face masks due to covid-19 has caused weight gain in everyone I know, including me. I’m trying breathing excercises to mitigate the effect.