HEALTH NEWS

Study Title:

Losing Weight Improves Immune Function

Study Abstract

Context: Obesity-related chronic inflammation is implicated in the pathogenesis of type 2 diabetes (T2D).

Objective: The objective of the study was to determine the effects of weight loss on immune cells in T2D and prediabetes.

Design and Setting: Thirteen obese subjects with T2D or prediabetes underwent 24 wk calorie restriction with gastric banding surgery at 12 wk.

Main Outcome Measures: Measures included weight, waist, and insulin resistance; surface activation marker expression on circulating immune cells; T-helper cell polarization: type 1 (Th1), type 2 (Th2), adipose tissue macrophage number and activation in sc and visceral adipose tissue.

Results: Mean total weight loss was 13.5%. There were significant decreases in expression of proinflammatory activation markers: granulocyte CD11b, monocyte CD66b, and T cell CD69 and CD25. Proinflammatory Th1 cell numbers fell by greater than 80%, as did the Th1 to Th2 ratio. The fall in Th1 to Th2 ratio related to weight (P < 0.05) and waist loss (P < 0.05). Reduction in immune cell activation was more pronounced in subjects with prediabetes. Weight and abdominal fat loss were predicted by lower activation of adipose tissue macrophage in sc and visceral adipose tissue (P < 0.05).

Conclusions: Calorie restriction before and after gastric banding attenuates activation of circulating immune cells of the innate and adaptive immune system in T2D and prediabetes. The role of immune cells in the chronic inflammation of obesity and T2D requires further investigation.

From press release:

Australian scientists have shown for the first time that even modest weight loss reverses many of the damaging changes often seen in the immune cells of obese people, particularly those with Type 2 diabetes.

The immune system is made up of many different kinds of cells that protect the body from germs, viruses and other invaders. These cells need to co-exist in a certain balance for good health to be maintained. Many factors, including diet and excess body fat, can tip this balance, creating immune cells that can attack, rather than protect, our bodies.

It has been known for some time that excess body fat, particularly abdominal fat, triggers the production of 'pro-inflammatory' immune cells, which circulate in the blood and can damage our bodies. In addition, other inflammatory immune cells, known as macrophages, are also activated within fat tissue.

The recent study looked at obese people with Type 2 diabetes or prediabetes who were limited to a diet of between 1000 and 1600 calories a day for 24 weeks. Gastric banding was performed at 12 weeks to help restrict food intake further. The study determined the effects of weight loss on immune cells

Undertaken by Dr Alex Viardot and Associate Professor Katherine Samaras from Sydney's Garvan Institute of Medical Research, the results showed an 80% reduction of pro-inflammatory T-helper cells, as well as reduced activation of other circulating immune cells (T cells, monocytes and neutrophils) and decreased activation of macrophages in fat. They are published in the Journal of Clinical Endocrinology Metabolism, now online.

"Excess weight disorders now affect 50% of adult Australians, with obesity being the major cause of Type 2 diabetes and some cancers," said Associate Professor Samaras.

"The situation has reached crisis point, and people must be made aware that excess fat will affect their immune systems and therefore their survival."

"We have found that a modest weight loss of about 6 kg is enough to bring the pro- inflammatory nature of circulating immune cells back to that found in lean people."

"These inflammatory cells are involved in promoting coronary artery disease and other illnesses associated with obesity."

"This is the first time it has been shown that modest weight reduction reverses some of the very adverse inflammatory changes we see in obese people with diabetes."

"We also showed that the activation status of immune cells found in fat predicted how much weight people would lose following a calorie restricted diet and bariatric surgery. Those with more activated immune cells lost less weight."

"It's the first time this has been described and is important because it helps us understand why some people lose weight more easily than others, and that inflammation is involved in regulating the response to bariatric surgery."

The Garvan study reinforces a message we hear regularly -- to optimise your health, keep your weight and waist in the healthy range.

Study Information

1.A. Viardot, R. V. Lord, K. Samaras.
The Effects of Weight Loss and Gastric Banding on the Innate and Adaptive Immune System in Type 2 Diabetes and Prediabetes
Journal of Clinical Endocrinology & Metabolism,
2010 April
Garvan Institute of Medical Research, Sydney, Australia