Daily aspirin therapy is best known for reducing risk of heart attack or stroke in high-risk patients. It’s a low-cost, over-the-counter, and globally accessible intervention. While the work is still preliminary, the same treatment could also protect women at high risk of HIV infection.
Published in the Journal of the International AIDS Society, the study was led by the University of Manitoba in collaboration with researchers in Nairobi, Kenya.
Inspired by female sex workers who were exposed to HIV over and over without being infected, it was previously shown that this natural immunity was likely founded on unusually low inflammation in the blood and genital tract.
On the flip side of the coin, PrEP is the current daily treatment for HIV prevention. It’s a vaginal gel that delivers antiviral drugs, and it doesn’t work in women with heightened genital inflammation.
To be transmitted a new person, HIV first needs to come in contact with CD4-positive T cells, which are the immune cells that HIV infects. When activated, these target cells are even more susceptible to infection.
The team wondered whether an anti-inflammatory drug like aspirin might be able to reduce vaginal inflammation. The goal was to lower the number and activation of target cells in the genital tract to give women a similar inflammation profile to the ones with natural HIV resistance.
The study recruited low-risk HIV seronegative women in Nairobi to participate in the pilot. They were treated for six weeks with an anti-inflammatory drug: either aspirin (n = 37) or hydroxychloroquine (n = 39). At the end of the study, the researchers measured the inflammation levels in their blood and genital tracts.
Both groups experienced reduced inflammation in the blood. However, aspirin was the more successful intervention, reducing the number of HIV target cells in the genital tract by 35 percent. This reduction approached the levels found in the women with natural HIV resistance. The target cells that were present were also less activated.
“Further research is needed to confirm our results with aspirin and test whether this level of target cell reduction will actually prevent HIV infections,” said principal investigator Keith Fowke in a statement.
“If so, this could be a strategy for HIV prevention that is not only inexpensive, but easily accessed globally. People living in poverty are disproportionately at risk of acquiring HIV. We need prevention approaches that are affordable and immediately available.”
There is still more work to be done. It still isn’t known whether the same results would be observed in women at high risk of HIV exposure. Longer term treatment or higher doses may also further reduce HIV target cells in the genital tract. The study used a similar dose to that used for heart attack and stroke prevention, which is known to be relatively safe for daily use.
Unlike PrEP, aspirin is free from stigma, and therefore it may be more readily adopted by the marginalized women who would benefit most.
Notably, all current HIV prevention strategies are anti-viral. This could become the first to act on the host and not the virus. That means that there is lower risk of developing HIV resistance, because there would be no selective pressure for HIV to evolve around.
Although this strategy doesn’t aim to bring the HIV transmission risk to zero, it carries many benefits. Easily accessed anywhere on the globe without a prescription, it could be widely adopted. It would also represent an entirely new strategy for HIV prevention that could help end the HIV pandemic.