Global Expression of Molecular Transporters in the Human Vaginal Tract: Implications for HIV Chemoprophylaxis

et al. (2013) Global Expression of Molecular Transporters in the Human Vaginal Tract: Implications for HIV Chemoprophylaxis. PLoS ONE 8(10): e77340. doi:10.1371/journal.pone.0077340 Global Expression of Molecular Transporters in the Human Vaginal Tract: Implications for HIV Chemoprophylaxis Manjula Gunawardana 0 Madeline Mullen 0 John A. Moss 0 Richard B. Pyles 0 Rebecca J. Nusbaum 0 Jignesh Patel 0 Kathleen L. Vincent 0 Charles Wang 0 Chao Guo 0 Yate-Ching Yuan 0 Charles D. Warden 0 Marc M. Baum 0 Alan Landay, Rush University, United States of America 0 1 Department of Chemistry, Oak Crest Institute of Science , Pasadena , California, United States of America, 2 Departments of Pediatrics and Microbiology and Immunology, UTMB, Galveston, Texas, United States of America, 3 Human Pathophysiology and Translational Medicine Graduate Program, UTMB, Galveston, Texas, United States of America, 4 Center for Biomedical Engineering, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America, 5 Functional Genomics Core, Beckman Research Institute, City of Hope Comprehensive Cancer Center, Duarte, California, United States of America , 6 Bioinformatics Core , Department of Molecular Medicine, City of Hope National Medical Center , Duarte, California , United States of America Background: Pre-exposure chemoprophylaxis (PrECP) using antiretroviral agents is a promising strategy for the prevention of sexual HIV transmission in women. Molecular transporters in the human vaginal tract (VT) may play a pivotal role in determining drug disposition and, consequently, pharmacodynamic outcomes in these efforts. Little is known, however, on the expression of these transporters in vaginal tissues, representing a critical knowledge gap. Methodology/Principal Findings: Our study analyzed the genome-wide transcriptome in 44 vaginal tissue samples from 6 reproductive-age women undergoing gynecologic surgeries. The analysis revealed that, unexpectedly, a large number (43%) of gene isoforms corresponding to membrane transporters were over-expressed (above the median expression level) in all samples. A subset of 12 highly expressed membrane transporters was identified and contained 10 members (83%) of the solute carrier superfamily. The largest difference in membrane transporter gene expression was observed across subjects, but more subtle differential expression also was found along the anteriorposterior axis of the VT. Cross-validation of the microarray analyses with measurements RT-qPCR demonstrated high concordance between these data sets. Immunofluorescence labeling of membrane transporter proteins in vaginal tissues was highly dependent on tissue/cell types. Conclusions/Significance: Antiretroviral PrECP drugs currently under evaluation are substrates for molecular transporters that were commonly expressed, but fell into both over- or under-expressed categories in all samples, suggesting a complex role for carrier-mediated processes in determining the disposition of these xenobiotics in vaginal tissues. These findings hold important implications for the successful development of products, either oral or intravaginal, for female-controlled HIV PrECP. - Funding: Research reported in this publication was supported by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health under Award Number R01AI100744. Funding support under Award Number 1UL1RR029876-01 from the National Center for Research Resources, National Institutes of Health, also is acknowledged. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist. As the HIV/AIDS pandemic enters its fourth decade, infection rates remain alarmingly high. The global incidence of HIV was estimated at 2.6 million in 2009, and 22 million more people are predicted to acquire HIV by 2031 [1,2]. These formidable statistics highlight the urgent need for effective antiretroviral pre-exposure chemoprophylaxis (PrECP) to prevent transmission in vulnerable populations. Systemic and topical PrECP using antiretroviral (ARV) agents is showing clinical promise for prevention of sexual HIV transmission [3-8], but there also have been a number of failed trials [2,9]. While the reasons for failure are unclear, it is undeniable that an appropriate drug disposition in key pharmacologic compartments is critical for a successful PrECP strategy [10-12]. Antiretroviral drugs have complex pharmacokinetic (PK) properties involving extensive drug metabolism, and transport by membrane-associated carrier proteins. Combination drug therapy often introduces drug-drug interactions that can result in toxic or sub-therapeutic drug concentrations and compromise treatment [13]. In addition, poor penetration of drugs into the intracellular compartment where HIV-1 replicates may contribute to the formation of virus sanctuary sites [14]. Molecular transporters from the ATP-binding cassette (ABC) and solute carrier (SLC) superfamilies are thought to play a central role in the disposition of ARV drugs [15-17]. Efflux systems can lead to a reduction of intracellular drug levels, decreasing antiviral activity and possibly promoting the development of resistant organisms [18]. Transporter-mediated absorptive processes may counter these effects [13]. Inhibition and induction of competing molecular transporters will lead to highly variable PKs among patients receiving PrECP, and the tissue-specific nature of transporter expression [13,19] introduces even more complexity. In the prevention of heterosexual HIV transmission in women, an understanding of types of molecular transporters present in the human vaginal tract (VT), and their interplay, is of critical importance. This area, however, remains largely unexplored [13]. Here, the global expression of membrane transporters in multiple locations of the VT of 6 women undergoing gynecologic surgery is described. A total of 44 tissue samples were studied by genome-wide transcriptome microarray analysis, and cross-validated with RT-qPCR measurements. Immunolocalization of membrane transporter proteins in these vaginal tissues also was carried out. The implications of these findings are discussed in terms of carrier-mediated drug disposition in HIV PrECP. Materials and Methods Subjects, vaginal tissue collection and processing This study conformed to the principles of the Declaration of Helsinki. The study protocol was approved by the Institutional Review Board of the University of Texas Medical Branch at Galveston (IRB 12-233). The participants took part voluntarily and provided verbal informed consent prior to enrollment that included permission to use the samples obtained in (...truncated)