Two over-the-counter allergy medicines may not only treat itching eyes and runny noses, but could also help reduce symptoms of obesity and diabetes, scientists say.  Two studies appearing in Nature Medicine show the allergy medications Zaditor and cromolyn can help control the immune system, which, scientists are now discovering, is linked to obesity and type 2, or adult-onset, diabetes.

 

Type 2 diabetes is a metabolic condition where the cells fail to use insulin properly. Scientists are now learning that type 2 diabetes might be tied to the immune system.

In one study, researchers found an abundance of mast cells—immune system cells that typically facilitate healing in wounded tissue by increasing blood flow to the site—in the fat tissue of obese and diabetic humans and mice compared to normal-weight fat tissue. If there are too many mast cells, the cells can become unstable and leak molecular “garbage” into the tissue, causing asthma and certain allergies.

 

By regulating the mast cells using Zaditor or cromolyn, Guo-Ping Shi, a biochemist from the Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, discovered improvements in both body weight and diabetes in mice. When the researchers gave a group of mice the over-the-counter allergy drugs and switched them to a healthy diet, the mice exhibited signs of near complete recovery, Shi and his colleagues say.

 

The findings were further bolstered when a group of mice that were genetically impaired to produce mast cells did not become obese or develop diabetes, despite being given a diet rich in sugar and fat for three months.

 

“The best thing about these drugs is that we know [they're] safe for people,” Shi says about the allergy medicines. “The remaining question now is: Will this also work for people?”

 

He says he intends to test cromolyn and Zaditor on obese and diabetic primates.

Another study from Harvard Medical School and the Joslin Diabetes Center shows that the fat tissue of diabetic and obese subjects had different amounts of certain immune system cells compared to the fat tissue of normal-weight humans and mice. Regulatory T cells, or Tregs, were abundant in the abdominal fat tissue of normal-weight humans and mice, but were virtually absent in the same tissue from the obese and diabetic subjects.

 

A Treg is a blood cell that was once believed to only act as a guardian to the immune system, ensuring that when white blood cells attack a foreign pathogen they don't become overzealous and harm healthy host tissue. Recently, however, evidence suggests that malfunctioning Tregs could play a role in certain cancers and multiple sclerosis. Obese and diabetic subjects also had fat tissue full of inflammatory immune cells, macrophages, while healthy-weight subjects did not.

 

“I come at this studying the effects of obesity and why it can spread systemically to cause chronic health problems,” says endocrinologist Steven Shoelson, a professor of medicine at the Joslin Diabetes Center, who collaborated on the study. “It’s possible that the inflammation caused by macrophages results in insulin resistance. And it's more likely, from what we've just seen, that Tregs are keeping the macrophages in check in normal fat tissue, thus preventing inflammation.”