Potential impact of drugs of abuse on mother-to-child transmission (MTCT) of HIV in the era of highly active antiretroviral therapy (HAART).

This report is a summary of a symposium entitled "Mother-to-Child Transmission (MTCT) of HIV and Drugs of Abuse in Highly Active Antiretroviral Therapy (HAART) Era," organized by The National Institute on Drug Abuse, National Institutes of Health in Rockville, Maryland, October 13, 2009. In the pre-HAART era, the prevalence of MTCT of HIV was about 25% and exposure of pregnant mothers to drugs of abuse (illicit drugs and tobacco smoking) was a significant factor in MTCT. However, with the introduction of HAART, the rate of MTCT of HIV has decreased to less that 2%. In the Unites States, it is estimated that currently about 5.1% of pregnant women use illicit drugs and 16.4% smoke tobacco. The residual prevalence of MTCT in the HAART era is still of concern and may be related to this continued prevalence of substance use among pregnant mothers. In this report, we review and present evidence that supports the hypothesis that drugs of abuse do have the potential to increase MTCT of HIV in the presence of HAART. Exposure to drugs of abuse during pregnancy may increase MTCT of HIV through a variety of mechanisms including possible damage to the placenta, induction of preterm birth, and increasing maternal plasma viral load through a variety of putative mechanisms such as: a) promoting HIV mutation and replication through non-adherence to HAART; b) impairing the efficacy of HAART through drug-drug interaction; and c) promoting HIV replication in monocyte/macrophages. Drugs of abuse may promote HIV replication by increasing the expression of CCR5 receptors, decreasing the expression of CCR5 receptor ligands, increasing the expression of CXCR4 receptors, increasing the expression of DC-SIGN, and possibly inducing epigenetic changes.