Inflammation in the Testicles Could Explain the Link Between Obesity and Reduced Fertility

Obesity is a major global health issue and continues to rise. In addition to a variety of chronic diseases such as diabetes and cardiovascular disease, obesity is also associated with reduced sperm quality and male infertility. Scientists have also associated obesity with increased inflammation. In obese people, chronic inflammation can occur in various tissues, and previous studies show that fat cells can produce and release specific signaling proteins that trigger inflammatory responses.

Sperm Concentration and Motility Reduced in Overweight Men

Some studies have associated chronic inflammation with impaired sperm production and function, but it was not known whether obesity-related inflammation could affect fertility. Researchers from China hypothesized that the chronic inflammation associated with obesity could affect the male genital tract, which includes the reproductive organs including the testes, and presented a possible mechanism to explain the link between obesity and male infertility. The study was published in the open access journal Frontiers in Physiology.

To investigate this, the researchers compared the concentration of inflammatory markers in the genital tracts of normal male mice and those that were fed a high-fat diet to become obese. They found that the obese mice had structural changes in their testes and changes in sex hormone secretion. These included decreased levels of testosterone – a sex hormone that may help maintain the protective blood-testis barrier, an important shield that protects sensitive tissues in the testes from components in the blood. The team also observed increases in inflammatory proteins in the testes of the obese mice. These included proteins that previous studies have found can impair sperm function, as well as proteins that can affect cells in the testes involved in sperm production.

Next, the research team analyzed human semen samples for sperm quality and inflammatory markers. These samples were provided by 272 donors: 82 of healthy weight, 150 of overweight, and 40 of obese. They found significantly increased levels of inflammatory proteins in overweight and obese donors, with the levels of these proteins correlating with the donors’ BMI. Similarly, sperm concentration and motility, two important indicators of fertility, were significantly reduced in overweight and obese donors, and both decreased as BMI increased.

Reduction of Chronic Inflammation

The results suggest that chronic inflammation caused by obesity can damage the male genital tract and lead to lower fertility. However, further research is needed to confirm this. The researchers believe that chronic inflammation caused by obesity can lead to sperm abnormalities and damage the blood-testis barrier. The study not only provides insights into the mechanisms linking obesity and infertility, but could also help develop therapies to improve male fertility. Tackling obesity is likely to be a good strategy as it also offers a range of additional health benefits.

“Obesity is a serious problem in modern society and both obesity and male infertility rates continue to rise,” says Zhide Ding of Shanghai Jiao Tong University, School of Medicine in China and senior researcher on the study. Reducing BMI is important for improving male fertility. Another possibility could be to develop targeted treatments to reduce chronic inflammation in the male genital tract in order to prevent damage and reduced fertility.