PrEP Medications Alter Immune System Functions Without HIV Infection
Researchers at the Trinity Translational Medicine Institute (TTMI) and clinicians at St. James Hospital discovered that Pre-Exposure Prophylaxis drugs used to prevent HIV alter immune system functions even in the absence of an infection. The study tracked gay and bisexual men receiving PrEP treatment at St. James Hospital longitudinally over six to nine months to observe how their immune systems responded to the medication.
The findings reveal that antiretroviral drugs change the structure of monocytes over time. Monocytes are white blood cells that act as first responders when viruses enter the body. PrEP impacts immune cell metabolism, increasing the volume of white blood cells released to combat potential infections. While these medications have transformed HIV into a manageable chronic condition, patients taking long-term antiretrovirals face higher rates of cardiovascular conditions like heart disease and inflammatory organ issues compared to HIV-negative individuals.
Tracking Immune Responses Without HIV Interference
Investigating how HIV affects the immune system is difficult because the presence of the virus makes it nearly impossible to separate viral impacts from antiretroviral side effects. By studying patients taking PrEP, researchers isolated the physiological impact of the drugs independently of the virus.
We chose to study the cohort of men who were taking PrEP because they’re a way to study the effect of anti-retrovirals in the absence of [HIV],
said Dr. Sharee Basdeo, deputy director at TTMI and senior author of the study alongside clinician Dr. Liam Townshend.
By analyzing innate immune cell responses, Dr. Basdeo and her colleagues aim to improve both the lifespan and the long-term health of individuals on PrEP. If you can fine tune what the mechanism is, you’ll be able to target it; to stop it, or promote it,
Dr. Basdeo stated.
Addressing Tuberculosis Susceptibility in Immunocompromised Patients
Beyond general immune alterations, the research team examined how PrEP affects patient vulnerability to tuberculosis, which remains the leading cause of death for individuals testing positive for HIV. Many patients suffering from both conditions lack access to effective treatment across the global south, including World Health Organization regions in South-East Asia, the Western Pacific, and Africa.
Researchers stimulated white blood cells extracted from patients with tuberculosis to observe cellular responses. While the presence of PrEP lowered the tuberculosis risk factor slightly over time, patient immune vulnerability remained elevated compared to baseline levels found in HIV-negative individuals. Dr. Basdeo noted the importance of observing these interactions to reduce the impact of bacterial infections in immunocompromised populations.
Frequently Asked Questions About PrEP and Immune Research
How long were patients monitored during the St. James Hospital study?
Patients receiving PrEP treatment at St. James Hospital were followed longitudinally over a span of six to nine months.
Which institutions led the research into PrEP immune impacts?
Researchers from the Trinity Translational Medicine Institute collaborated with clinicians at St. James Hospital, with Dr. Sharee Basdeo and Dr. Liam Townshend serving as senior authors of the study.
How does PrEP affect white blood cells in patients?
PrEP changes the structure of monocytes—the white blood cells that act as viral first responders—and alters immune cell metabolism by increasing the release of white blood cells.