Protein Protects Women Against Obesity

Obesity is on the rise in the United States, and it is linked to poorer health outcomes and a lower quality of life. Currently, more than 30% of American people are classed as obese. Obesity is a major and growing public health concern since it is a risk factor for various diseases, including diabetes, cardiovascular disease, and COVID-19.

A team of scientists at the University of California, Riverside discovered that, as compared to male mice, female mice are protected against obesity and inflammation because they secrete more of an immunological protein called RELMalpha.

“Our study identifies immune cells and RELMalpha in causing these sex-specific differences in the immune response to obesity,” said Meera G. Nair, an associate professor of biomedical sciences in the School of Medicine, who co-led the study published in eLife with Djurdjica Coss, a professor of biomedical sciences.

RELM, or resistin-like molecules, are a class of proteins released by mammals that are abundant in infectious and inflammatory illnesses. RELMalpha, one of these proteins, is promptly activated in the mouse body upon infection and serves to protect the body’s tissues. It has the same sequence and function as resistin in humans.

“RELMalpha regulates two immune cell types: the anti-inflammatory macrophage and the eosinophil,” Nair said. Macrophages and eosinophils are types of disease-fighting white blood cells but can be damaging to the body in the absence of infection. “In contrast, males expressed less RELMalpha, had less eosinophils, and had inflammatory macrophages that promoted obesity.”

When the researchers removed RELMalpha from female mice, they discovered that the mice were no longer protected from obesity, had less eosinophils, and had inflammatory macrophages, just like male mice.

“However, we were able to reduce obesity in these female mice by treating them with eosinophils or with RELMalpha, suggesting promising therapeutic targets,” Nair said. “We are the first to map this pathway in females that protects against obesity.”

The researchers discovered that RELMalpha deficiency had substantial impacts in males as well, albeit to a lesser extent than in females.

“In our experiments, female mice had higher levels of RELMalpha than males, which likely explains why RELMalpha deficiency affected females more than males,” Coss said. “The implications of our study are that consideration of sex differences is critical to tackle metabolic diseases such as obesity.”

The study, according to Nair, is interesting in that it demonstrates a previously unknown role for RELMalpha in modifying metabolic and inflammatory responses during diet-induced obesity that is sex dependent.

“Our results highlight a critical ‘RELMalpha–eosinophil–macrophage axis’ that functions in females to protect from diet-induced obesity and inflammation,” she said. “Promoting these pathways could, therefore, provide novel therapies for combating obesity.”

Source Link