Do certain contraceptives increase STI susceptibility?

The relationship between some oral contraceptives and an increased susceptibility to sexually transmitted infections (STIs), including HIV, is a new investigation funded by the Bill and Melinda Gates Foundation.

In 2013, a team of researchers, led by Centre Director Professor Paul Hertzog, characterised an important, naturally occurring immune cytokine in the female reproductive tract which regulates immunity to STIs. The team had previously discovered and named it Interferon Epsilon (IFN-epsilon). This world-first discovery was published in the prestigious journal Science and it has many implications for future studies into the prevention of diseases of the female reproductive tract including STIs.

Contraceptives link to STI susceptibility

Progesterone-based contraceptives have been linked to an increased susceptibility to STIs, which Professor Hertzog hypothesises is caused by progesterone suppressing the expression of IFN-epsilon in the female reproductive tract, rendering women taking progesterone-containing contraceptives more susceptible to infections.

“Certain progesterone-based contraceptive formulations are one of the cheapest, most widely used contraceptives globally. Our study is the first of its kind aimed at characterising how progesterone is linked to supressing IFN-epsilon expression. If we can achieve this, then we can investigate potential solutions and, potentially to contribute to the reduction of the high global incidence of HIV infection,” said Professor Hertzog.

In recent years, the Gates Foundation has initiated a strong program of family planning activities, which has included a significant investment in making contraceptives available to 220 million women in western Africa, India and Indonesia.

Finding safe and effective contraceptive solutions

Providing women in developing countries with hormone-based contraceptives is aimed at helping mothers plan their pregnancies and reduce high infant mortality rates. If progesterone-based contraceptives are linked to increased STIs and HIV susceptibility, however, then alternative contraceptive options need to be considered. For this reason, the foundation has funded Professor Hertzog’s study as a step to determining the most safe and effective contraceptive solutions for women globally.

To do this, Professor Hertzog will lead a team of international research collaborators including scientist Professor Sam Mesiano from Case Western Reserve University and clinician-researcher Professor Sharon Achilles from the University of Pittsburgh, to conduct a comprehensive investigation into the mechanism behind progesterone regulation of IFN-epsilon and the identification of biomarkers for monitoring interferon epsilon activity in women.  The team will use a diversity of patient samples to screen for selective progesterone receptor modulators (SPRMs) to determine if they can maintain contraceptive efficacy without repressing IFM-epsilon expression.

HIV help needed

Currently more than 33 million people are living with HIV and, while huge progress has been made in increasing access to HIV treatment in the past decade, the pandemic continues to outpace efforts to control it, with the number of newly infected people each year outnumbering those who gain access to treatment by two to one.

Children are being born with HIV at a rate of 300,000 per year and half of them won’t reach their second birthday.