Mucosal tenofovir 1% gel stimulates cell proliferation and type I/III interferon pathways

Oral tenofovir is a key antiretroviral used for treatment and pre-exposure prophylaxis (PrEP) of human immunodeficiency virus (HIV). A gel form has been tested for vaginal and rectal PrEP. We have shown that 7 days of tenofovir 1% gel had broad-ranging effects on gene expression in the rectum, especially suppression of anti-inflammatory mediators and induction of cell proliferation. Similarly, oral PrEP induced type I/III interferon-stimulated genes in the gut. It is unknown how long these effects last and whether they occur in other relevant body compartments. We measured the transcriptomes and proteomes of tissue samples obtained before and after daily topical tenofovir 1% gel application for 14 days (Microbicide Trials Network [MTN]-014 trial, rectal and vaginal) or 56 days (MTN-017 trial, rectal). While many changes seen after 7 days diminish after 14 and 56 days, some remain, notably increases in cell proliferation- and type I/III interferon-related genes. Vaginal gel uniquely induces changes related to epithelial-mesenchymal transition and angiogenesis. Induction of type I/III interferon-related genes is the most consistent and persistent mucosal response to tenofovir, occurring after both oral and topical use and at all tested time points. Hypothetically, interferon induction could improve antiviral efficacy, but also contribute to an increased chronic disease burden in people with HIV.

Analyzing gene expression data from three separate clinical trials, we find that the antiretroviral drug tenofovir, which belongs to the class of nucleotide analogue reverse transcriptase inhibitors, induces the type I/III interferon system of innate immunity in the mucosa. This effect occurs in the absence of HIV infection and manifests itself over various treatment durations and after both oral and topical drug delivery. Tenofovir and other related medications are important components of long-term antiretroviral treatment taken by people living with HIV. Therefore, this unexpected immunological effect might need to be considered as a potential contributor to comorbidities in people living with HIV, as well as an immunopharmacological co-factor when testing novel HIV cure interventions.

This study is registered with ClinicalTrials.gov as NCT01768962, NCT01687218, and NCT01232803.