Obesity is a chronic disease associated with impaired mental health and reduced quality of life, and its prevalence in the United States is increasing. Currently, more than 30% of adults are classified as obese. As a risk factor for numerous diseases – including diabetes, cardiovascular disease, and COVID-19 – obesity is a serious problem.
In a study conducted at the University of California, Riverside, scientists used a mouse model fed a high-fat diet. The results showed that females were more resistant to the development of obesity and inflammation than males, and this was associated with increased secretion of the immune protein RELMα.
According to Meera G. Nair, this protein plays a key role in sex-specific differences in the immune response to obesity. The study was published in the journal eLife, in collaboration with Djurdjica Coss.
RELM proteins (resistin-like molecules) are a group of proteins that are naturally secreted in mammals and are often elevated in conditions of infection and inflammation. RELMα is rapidly activated after infection and has a protective role in preserving tissues. This protein regulates two important types of immune cells:
- Anti-inflammatory macrophages
- Eosinophils
Although these cells already have a known protective function against pathogens, in the absence of infection, they can contribute to tissue damage. In males, lower levels of RELMα, fewer eosinophils, and increased numbers of pro-inflammatory macrophages were observed – all of which contribute to the development of obesity.
In experiments in which RELMα was removed in females, protection against obesity was lost, with decreased eosinophils and an increased number of inflammatory macrophages.
However, re-administration of RELMα or eosinophils decreased obesity, suggesting therapeutic potential. Although RELMα deficiency also affected males, the effect was significantly weaker than in females, likely due to their naturally lower levels of this protein.
In conclusion, the results indicate the importance of sex differences in the development of metabolic disorders such as obesity. A new biological axis-RELMα-eosinophils-macrophages – was also identified, which has a protective role against obesity and inflammation in females. These findings open the possibility of developing new therapeutic measures through these mechanisms to prevent and treat obesity.
