April 16, 2020
A recently published study led by Dr. Gregg Dinse provides compelling evidence that proteins found in many people with autoimmune diseases have become more common in Americans over time. Using blood samples taken from 14,211 people representative of the American population, the researchers found that these proteins, also known as anti-nuclear antibodies (ANA), significantly increased between 1988 and 2012 in the overall U.S. population. These results suggest that people may becoming more susceptible to developing autoimmune diseases like lupus.
Antibodies are proteins produced by immune cells known as B cells. During viral and bacterial infections, the antibodies trigger the immune system to eliminate pathogens. Problems arise when B cells produce antibodies like ANA that attack healthy human cells instead. While most ANA+ people do not experience any symptoms, a small number may develop autoimmune diseases later as studies show that ANA can be found in patients years before an autoimmune diagnosis. This makes it a useful tool for gauging whether the rate of autoimmunity is likely increasing or decreasing in a population.
While it was previously suspected that autoimmunity is becoming more common, there have not been studies to directly compare the frequency of ANA in Americans today relative to 10 or 20 years ago. Dr. Dinse and his colleagues addressed this knowledge gap by using frozen blood samples obtained from 14,211 participants enrolled in a decades-long health and nutrition study. The number of people was split evenly between three time periods: 1988-1991, 1999-2004, and 2011-2012. They found ANA in 11.0% of the samples taken between 1988-1991, 11.5% in 1999-2004, and 15.9% in 2011-2012.
The authors found that the frequency of Americans with anti-nuclear antibodies significantly increased between 1988 and 2012 in the overall population, and more specifically in males and females with the following characteristics:
- Non-Hispanic white race/ethnicity
- Aged 12-19 or 50+
- Exposed to second-hand smoke
- Moderate/heavy drinking
- Overweight/obese
There was no significant change in non-Hispanic black and Mexican-American racial/ethnic groups over that time period.
While it is troubling that the frequency of ANA+ Americans is increasing, only a small percentage of healthy people with anti-nuclear antibodies develop autoimmune diseases. Even though early treatment of autoimmunity would be beneficial, clinicians are currently unable to predict which ANA+ patients will go on to develop disease and those that will not. Long-term studies on ANA+ individuals are needed to identify potential risk factors and biomarkers that allow for better identification and treatment of symptom-free people with early stages of autoimmunity.
Dr. Dinse is with Clinical and Public Health Sciences, Social & Scientific Systems in Durham, North Carolina.
