The findings may explain why clogged arteries, a condition called atherosclerosis, have been tied to autoimmune disorders, which develop when the immune system goes awry.
"The lesson from this study is that immune diseases are not always a matter of immune system alone," said senior study author Yeonseok Chung, of the University of Texas Health Science Center at Houston. "With our findings, we have just started to understand how factors in the circulatory system impact the immune system."
Levels of the molecule in question, oxidized low-density lipoprotein (oxLDL), rise when the immune system is activated. The study authors wondered if this might have a bearing on why people with autoimmune conditions, such as psoriasis and rheumatoid arthritis, are more likely to develop clogged arteries.
In the new study, which was published Jan. 9 in the journal Immunity, the researchers found that the molecule increased certain immune cells in mice that had the equivalent of human atherosclerosis.
When those immune cells were treated with an agent that inhibits their activity, symptoms of autoimmune disease improved.
"Our study suggests that we should consider circulatory factors in current therapeutic approaches for the treatment of autoimmune diseases," Chung said in a journal news release. For instance, controlling oxLDL levels in circulation might greatly improve the effectiveness of treatments for autoimmune diseases, Chung added.
Experts note that results achieved in animal studies often aren't replicated in humans.
For more about vascular diseases, see the U.S. National Library of Medicine.