October 1, 2012

Natural-born Killer T-cells may protect against Obesity


Invariant natural killer T-cells (iNKT) are immune cells that are shown to protect against diet-induced obesity and the metabolic syndrome. The study was published this week in the journal Immunity.

This type of anti-tumor immune cell is naturally occurring in the body. When a human becomes obese the amount of this T-cell is fewer than in lean individuals. However, when the obese individual loses weight the body restores the levels of iNKT. Using this information, researchers wanted a better understanding of the role iNKT plays in obesity.

Researchers hypothesized that iNKT cells play a role in fat tissue regulation and protect against the development of inflammation and the metabolic syndrome.  They designed a study using two types of mice, both deficient in iNKT and a group of control mice. All 3 groups were fed a high-fat diet.

The proof’s in the pudding. Over a 6 week trial, all the animals grew obese. But the iNKT-deficient mice grew 30% fatter than the control animals and developed the mouse equivalent of Type 2 diabetes. The mice also had greatly increased triglyceride levels, larger fat cells, and fatty liver disease.

Here’s where iNKT saves the day. Next, the authors removed iNKT cells from a normal mouse and injected them into obese NKT-deficient mice. The results? The mice experienced a reversal of Type 2 diabetes and weight loss despite continuing to eat the high-fat diet. Insulin sensitivity improved, as did triglycerides and leptin. These mice also decreased the size of their fat cells. 

What compelled the researchers to look at immune cells as the catalyst of this problem? “We knew that not only did obese patients have more heart attacks and a greater incidence of type 2 diabetes than lean individuals, but they also developed more infections than non-obese individuals,” said Dr. Lydia Lynch.

The researchers found a single dose of aGC caused a dramatic improvement in the obese animals. Their metabolism increased and fatty liver disease mitigated. They lost much of the weight gained and experienced reversal of diabetes.

Is aGC the panacea for Type 2 diabetes and obesity? “The effect of NKT stimulation, whether by aGC or other means, on weight loss, obesity, and metabolic disorder has not been investigated until now and may provide a new avenue for the treatment of obesity and metabolic syndrome, which have now reached epidemic proportions worldwide.”

Ah science. Let this approach have its day in court and see where it lands us in the futile fight against obesity and Type 2 diabetes. If it does have legs, as Mickey says, you ain’t seen nuthin’ yet!

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