The search for answers to hormonal contraception's role in HIV infection

July 22, 2016 by Thomas L. Cherpes, The Conversation
Injectable progestin contraceptives are particularly popular in sub-Saharan Africa. Credit: Shutterstock

About 75% of HIV-infected people in sub-Saharan African between the ages of 15 and 24 are women. Many factors play a role in this gender imbalance. These include gender-based social disparity and a high prevalence of intergenerational sexual partnerships.

But research suggests certain types of hormonal contraceptives commonly used in this region could also play a role.

Injectable progestin contraceptives, like Depo-Provera, are particularly popular in sub-Saharan Africa. They are effective and convenient. Instead of taking a daily pill, can receive Depo-Provera injections every three months.

But studies suggest that women using this specific type of contraceptive are more susceptible to HIV. Most recently a large-scale study conducted in Africa found women using injectable progestins were twice as likely to acquire HIV than women using no hormonal contraceptive.

This type of study cannot prove a particular type of contraceptive actually makes women more susceptible to infection, as it is just looking for an association between the two.

To really find out if contraceptives make women more susceptible to infection, you need to see how these drugs actually affect the systems that protect the body from infection. Such studies are more difficult to do in humans, so my colleagues and I decided to explore mouse models.

What we learnt from mice

We used mice to learn if Depo-Provera or levonorgestrel (LNG), a progestin used in hormonal intrauterine devices, affect the genital mucosal barrier. This barrier serves as a blockade to prevents virus and bacteria from infecting body tissues. In other words, it is a first line of defense against infection.

Epithelial cells on the surface of genital tract tissues are a vital part of this barrier. They are held tightly together by that make it difficult for pathogens to penetrate tissue and establish infection.

But we found that mice treated with Depo-Provera or LNG have lower levels of several of these adhesion molecules. This means that genital epithelial cells aren't held together as tightly, tissue becomes more permeable and virus more easily invades.

Our research shows these contraceptives increase mouse susceptibility to infection. But do similar changes in permeability also occur in women?

To find this out, we obtained cervical tissue from US women before and after they started using Depo-Provera. This showed Depo-Provera causes changes to adhesion molecules and tissue permeability similar to those seen in mice.

Where do we go from here?

Sexually transmitted infection and unplanned pregnancy are interconnected public health problems. Countries with a larger burden of infection typically also have higher infant and maternal mortality rates and a great need for effective contraception.

Since Depo-Provera and LNG provide women with effective contraception, we wanted to learn if there are ways to counteract their ability to weaken the mucosal barrier. With this in mind, we also performed studies in which mice were treated with both Depo-Provera and oestrogen.

This combination strengthened the genital mucosal barrier and made mice less susceptible to virus infection. It also suggests a scenario in which women would receive Depo-Provera and a vaginal ring that releases oestrogen and an antiviral microbicide.

Before this can happen, research is needed to determine if Depo-Provera and an oestrogen-releasing vaginal ring protect non-human primates from viral . If positive results are seen, the next logical step would be clinical trials that explore if similar approaches also reduce a woman's risk of acquiring HIV.

Explore further: Condom use among high school girls using long-acting contraception

Related Stories

Condom use among high school girls using long-acting contraception

March 14, 2016
High school girls who used intrauterine devices and implants for long-acting reversible contraception were less likely to also use condoms compared with girls who used oral contraceptives, according to an article published ...

Study in Lancet finds use of hormonal contraception doubles HIV risk

October 3, 2011
Women using hormonal contraception --such as a birth control pill or a shot like Depo-Provera – are at double the risk of acquiring HIV, and HIV-infected women who use hormonal contraception have twice the risk of transmitting ...

Why do certain hormonal contraceptives increase the risk of HIV?

September 1, 2015
In recent years, evidence has been building that injectable contraceptive depot medroxyprogesterone acetate (Depo-Provera or DMPA) is associated with an increased risk of HIV infection. Now a study published in the September ...

Contraceptive implants and injections associated with repeat abortions

December 10, 2015
Women who used contraceptive implants or injections after an initial termination were among those with an increased likelihood of a repeat abortion in the long term, finds a study published online in the Journal of Family ...

Risk of HIV infection in studies of African women using hormonal contraceptives

January 22, 2015
Use of the injectable progestin contraceptive depot-medroxyprogesterone acetate (DMPA) is linked to an increased risk for HIV infection, according to an article published by Charles Morrison of FHI 360 and colleagues in this ...

Recommended for you

Paris spotlight on latest in AIDS science

July 21, 2017
Some 6,000 HIV experts gather in Paris from Sunday to report advances in AIDS science as fading hopes of finding a cure push research into new fields.

Scientists elicit broadly neutralizing antibodies to HIV in calves

July 20, 2017
Scientists supported by the National Institutes of Health have achieved a significant step forward, eliciting broadly neutralizing antibodies (bNAbs) to HIV by immunizing calves. The findings offer insights for HIV vaccine ...

Heart toxin reveals new insights into HIV-1 integration in T cell genome

July 20, 2017
Human immunodeficiency virus (HIV)-1 may have evolved to integrate its genetic material into certain immune-cell-activating genes in humans, according to new research published in PLOS Pathogens.

Scientists capture first high-resolution image of key HIV protein transitional state

July 13, 2017
A new, three-dimensional snapshot of HIV demonstrates the radical structural transformations that enable the virus to recognize and infect host cells, according to a new study led by scientists at The Scripps Research Institute ...

Barrier to autoimmune disease may open door to HIV, study suggests

July 11, 2017
Researchers from the University of Colorado School of Medicine have discovered that a process that protects the body from autoimmune disease also prevents the immune system from generating antibodies that can neutralize the ...

Team tests best delivery mode for potential HIV vaccine

June 20, 2017
For decades, HIV has successfully evaded all efforts to create an effective vaccine but researchers at The Scripps Research Institute (TSRI) and the La Jolla Institute for Allergy and Immunology (LJI) are steadily inching ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.