Researchers Find Cause, Possible Treatment for Cardiovascular Risks in HIV Patients

The answer could be found in tick saliva.

Scientists are uncovering the pitfalls of improved HIV suppression therapy.

Chronic inflammation and persistent immune activation — a couple of long-term effects of HIV — are increasing cardiovascular risks in HIV patients over time, according to researchers at the National Institutes of Health (NIH).

Even for those with their infection under control with antiretroviral therapy (ART), HIV patients are twice as susceptible to heart attacks, strokes, and other cardiovascular disease than those not infected.

This is due to proliferating immune cells which trigger inflammation and abnormal blood clotting in HIV patients. Researchers have uncovered the mechanisms of that process — while also possibly finding a treatment for it.

Iran Sereti, MD, of NIH’s Laboratory of Immunoregulation at the National Institute of Allergy and Infectious Diseases (NIAID), and Ivona Pandrea, MD, PhD, of the University of Pittsburgh, led a team of researchers in testing HIV blood samples for high levels of tissue factor (TF), the protein associated with blood clotting and inflammatory processes.

The rate of monocyte immune cells that expressed high TF levels was present regardless of a patient’s response to ART therapy, according to the study. Only when researchers exposed samples to experimental anticoagulant Ixolaris — found in tick saliva and capable of blocking TF activation — did TF activity shut off in monocytes, without affecting the function of cells.

In an animal study featuring 5 monkeys infected with HIV-equivalent condition SIV, researchers observed similarly raised levels of TF-expressing monocytes. However, the monkeys treated with Ixolaris reported lower rates of abnormal blood clotting and immune activation — showing that shutting down the TF pathway may be the key to limiting the cardiovascular risk factor in HIV patients.

NIAID director Anthony S. Faruci, MD, said human trial is “still a way off” from materializing, though.

“We would want to get more animal studies,” Faruci said. “If it still holds true in safety and efficacy in animals, we could begin to move forward.”

Regardless, Faruci called the discovery involving a factor found in tick saliva a “potential therapeutic avenue,” noting it holds interesting potential for researching its ability to limit HIV conditions in patients.

Cardiovascular risks have been well known and associated with HIV patients — of both genders — for some time now, Faruci said. The treatment of virus infection itself is “highly, highly effective” with modern ART therapy that makes the virus nearly undetectable in cases of infection.

But with that efficacy comes this need to address the long-game of HIV infection. That’s what researchers are now focused on, Faruci said.

“We know we can treat the virus very well, and now we’re trying relieve the comorbidities,” Faruci said. “The longer people live with HIV, the more we see they live with these comorbidities, one of which is cardiovascular disease.”

The study, "Inflammatory monocytes expressing tissue factor drive SIV and HIV coagulopathy," was published online in Science Translational Medicine.

A press release regarding the study was made available.

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