When it comes to autoimmune diseases — conditions such as lupus, rheumatoid arthritis, and multiple sclerosis that cause a body to attack itself — women are at a higher risk than men.
But the reasons why aren’t completely clear.
Antinuclear antibodies (ANAs) are present in patients with autoimmune conditions, but the vast majority of ANAs haven’t been tied to certain diseases. Without good biomarkers to use when testing patients, diagnosis can be challenging, and prevention becomes nearly impossible.
So researchers at URMC are working to understand more. On Sept. 9, at the CTSI Seminar Series, Todd Jusko, Ph.D., assistant professor in the Department of Public Health Sciences and Department of Environmental Medicine, shared his past work and his search for an easy-to-identify biomarker.
What we know
Jusko was part of a group that looked at ANA prevalence in 4,340 individuals from the National Health and Nutrition Examination Survey, or NHANES between 1999 and 2003. Among those participants — 14 percent tested positive for ANAs in their blood. The proportion was slightly higher for African Americans, and, interestingly, slightly lower for individuals who were obese or overweight.
Women were also much more likely than men to test positive for ANA prevalence, particularly in their reproductive years, or just beyond. Overall, 18 percent of women tested positive for ANA, while 10 percent of men did. Women aged 30-39 were 2.5 times as likely to have ANAs in their blood as men. Women aged 40-49 were four times as likely. Nulliparous women — women who have not carried a pregnancy past 20 weeks — were also found to be much less likely to have ANAs present in their blood.
“Certainly, it’s related to some sort of hormonal difference,” said Jusko.
For a more recent study with the NHANES database, Jusko began searching for environmental causes of ANA. Dioxins and dioxin-like compounds have been documented to alter immune function, so it seemed logical that their presence may play a role in ANAs.
Jusko did find that one compound, triclosan, was biologically plausible as a potential cause of ANAs in men only, but his research revealed a variety of limitations with the data available. Jusko stressed the need for further studies measuring incident, or newly arising ANA and linking it to environmental chemicals.
“We were underpowered for some analyses. I know we had 4,300 people, which sounds like a lot, but some of the cycles didn’t measure the ANA or the chemical concentration,” he said. “So this was exploratory and this is far from the final word.”