The researches find that the females are less susceptible to infection but are 10 times more likely than males to develop an autoimmune disorder; such as hypothyroidism or rheumatoid arthritis. The female immune system is “a double-edged sword” in that way, said Jennifer Franko; a teaching assistant professor in the Department of Microbiology, Immunology and Cell Biology at the West Virginia University School of Medicine. In a new study funded by the National Institutes of Health, Franko is investigating if the gut microbiome the microbes that live in our digestive tract can alter sex-specific immune responses.
Female immune system
Her project will focus on short-chain fatty acids, metabolites that the bacteria in our gut produce as they break down the food we eat. “Short-chain fatty-acids are known to have immunologic effects. They can either enhance or suppress immune responses, depending on the context;” Franko said. But scientists have not yet explored if they can influence immune responses differently in men and women. That’s where Franko’s research comes in. She believes that SCFAs influence immune activation in a sex-chromosome-dependent manner.
Females typically have two X chromosomes, and males have one X and one Y. For this project, Franko and her colleagues will use unique animal models that don’t fall neatly into traditional male or female categories. For example, the male models can have either an XX or an XY sex chromosome complement; and females can have either XX or XY sex chromosomes. By providing these animal models with extra SCFAs in their water supply, Franko and her team will determine if SCFAs enhance the activity of B cells a type of white blood cell that helps the body target germs in animals with certain sex chromosome complements after they are vaccinated against Streptococcus pneumoniae; the culprit behind most cases of bacterial pneumonia.
Type of white blood cell
Franko hypothesizes that animal models with two X chromosomes whether they are biologically male or female will have B cells that are more active and that these models will induce a stronger response to the vaccine if they’ve taken in an abundance of SFCAs. Previous studies of the microbiome’s immunologic effects have not taken sex-chromosome-linked differences into account. “Most of the time, when you talk about microbiome research; researchers are looking to study changes in microbial communities. What our study suggests is that it doesn’t matter if males and females have the same communities,” Franko said. “If those communities influence the immune system differently; in a sex-chromosome-dependent manner; then immune activation is going to differ in girls and guys because of the genetic differences between them.”