In women, a strong link between human papillomavirus infection and heart disease has been identified by US researchers.
While the research is still in its early stages, experts said that if confirmed it could offer a promising new avenue in the fight against heart disease, which is the number one killer of women in most parts of the world.
"Nearly 20 percent of individuals with CVD (cardiovascular disease) do not show any risk factors, indicating that other 'nontraditional' causes may be involved," said lead author Ken Fujise, Director, Division of Cardiology at University of Texas Medical Branch.
"HPV appears to be one such factor among women," said Fujise, whose findings appear in the November 1 issue of the Journal of the American College of Cardiology.
HPV is the most common sexually transmitted disease, with more than 40 types, some of which can cause cervical cancer or genital warts, but most of the time HPV causes no symptoms at all.
At least 50 percent of sexually active men and women will get HPV at some point in their lives, according to the Centers for Disease Control and Prevention.
Often, the body can clear the infection on its own, but certain types, known as oncogenic strains, can turn into cancers and need to be closely monitored.
Researchers got the idea to investigate HPV as a potential cause of heart disease because of the way it causes cancer by inactivating two tumor suppressing genes: p53 and retinoblastoma protein (pRb).
The gene p53 is key to regulating the process that leads to hardening of the arteries, or atherosclerosis, while pRb is a crucial factor in regulating cell growth and proliferation.
While they have not confirmed this link and have not established whether or not HPV may cause heart disease, they did see that "oncogenic HPV types were strongly associated with CVD," said co-author Hsu-Ko Kuo, also of UTMB.
They did not see a link between HPV and other metabolic risks such as high cholesterol or high blood pressure.
The data was derived from a survey of 2,500 women age 20-59 who took part in the National Health and Nutrition Examination Survey (NHANES) from 2003 to 2006.
The women were tested for HPV DNA via self-collected vaginal swabs. A full 44.6 percent of the women in the survey tested positive for HPV, and 23.2 percent had cancer-causing HPV strains.
Because the swabs were self-collected, Fujise warned that the actual incidences of HPV could be higher than seen in the study. Similarly, women self-reported their rates of heart disease, which could leave some cases undiagnosed and therefore not included.
Future studies could seek to better understand how HPV infection relates to atherosclerosis, and could examine whether HPV vaccine has any impact on likelihood of developing heart disease, the study authors said.
Nieca Goldberg, medical director of the Women's Heart Program at New York University Langone Medical Center, told AFP the research provides an "out-of-the-box look at other factors that can increase women's risk for cardiovascular disease."
"This is the beginning of probably some very interesting research but more work has to be done," said Goldberg, who was not involved with the study.
"Women are likely to get their first heart attacks about 10 years after menopause but the risk starts early," she added.
"And although we know lots about traditional risk factors such as cholesterol, high blood pressure, diabetes, and smoking, I think it is important for us to look at other potential risk factors that can help us assess women at an earlier age and get them in the system."
If the link between HPV and heart disease is confirmed, scientists could work on developing a drug to stop the inactivation of the p53 gene and prevent heart disease in women with HPV, said Fujise. At present, no such drug exists.
In the meantime, doctors "should monitor patients with cancer-associated HPV to prevent heart attack and stroke, as well as HPV patients already diagnosed with CVD to avoid future cardiovascular events," he said.