Mucosal safety of PHI-443 and stampidine as a combination microbicide to prevent genital transmission of HIV-1.
OBJECTIVE
To investigate the in vitro and in vivo mucosal safety of a nonnucleoside reverse transcriptase (RT) inhibitor (PHI-443) and a nucleoside analogue RT inhibitor (stampidine)-based anti-HIV microbicide either alone or in combination.


METHODS
In vitro and in vivo studies using three-dimensional vaginal epithelia integrating Langerhans cells and 16 New Zealand White rabbits, respectively.


METHODS
Research laboratory.


METHODS
Rabbits in groups of four were exposed intravaginally to a gel with and without 1% PHI-443, 1% stampidine, or 1% PHI-443 plus 1% stampidine for 14 days. Cytokine/chemokine release by three-dimensional co-cultures in the presence and absence of PHI-443 or stampidine.


METHODS
Histologic scoring of vaginal tissue for mucosal toxicity at 24 hours after dosing. Simultaneous evaluation of levels of 10 cytokines (granulocyte-macrophage colony-stimulating factor, interleukin-1 alpha, interleukin-13, macrophage inflammatory protein-1 beta, granulocyte colony-stimulating factor, interleukin-18, tumor necrosis factor-alpha, interleukin-6, interleukin-1 beta, and interferon-gamma) and 6 chemokines (epithelial neutrophil-activating peptide-78, interleukin-8, monocyte/macrophage chemoattractant protein-1, macrophage inflammatory protein-3 alpha, interferon-inducible protein-10, and regulated upon activation of normal T-cell expressed and secreted) in culture media by a multiplexed chemiluminescence-based immunoassay.


RESULTS
In the rabbit model, repeated intravaginal administration of PHI-443 plus stampidine via a gel formulation at concentrations nearly 2,000 and 10,000 times higher than their respective in vitro anti-HIV IC(50) values did not result in vaginal irritation. The levels of proinflammatory cytokines/chemokines secreted by multilayered human genital epithelia integrating Langerhans cells were unaffected by prolonged exposure to PHI-443 or stampidine.


CONCLUSIONS
The combination of PHI-443 and stampidine was noncytotoxic to vaginal epithelial cells, nonirritating to vaginal mucosa, and did not induce the secretion of proinflammatory cytokines and chemokines by co-cultures of human genital epithelia and Langerhans cells. These attributes are particularly useful for the clinical development of PHI-443 and stampidine as a combination microbicide and as a prophylactic anti-HIV agent to curb genital transmission of HIV-1 by semen.
D'Cruz
Osmond J
OJ
Drug Discovery Program, Paradigm Pharmaceuticals, LLC, Patton Road, St. Paul, MN 55113, USA. odcruz@ih.org
Uckun
Fatih M
FM
D000282:Administration, Intravaginal; D000818:Animals; D000891:Anti-Infective Agents, Local / Q000008:administration & dosage / Q000009:adverse effects*; D054306:Dideoxynucleotides; D004359:Drug Therapy, Combination; D005260:Female; D015658:HIV Infections / Q000517:prevention & control / Q000635:transmission*; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D009092:Mucous Membrane / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D011725:Pyridines / Q000008:administration & dosage / Q000009:adverse effects*; D011817:Rabbits; D018119:Stavudine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*; D013890:Thiourea / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*; D013938:Thymidine Monophosphate / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*; D014621:Vagina / Q000166:cytology / Q000187:drug effects* / Q000502:physiology
D000891:Anti-Infective Agents, Local; D054306:Dideoxynucleotides; C403248:HI 443; D011725:Pyridines; C472384:stampidine; D013938:Thymidine Monophosphate; D018119:Stavudine; D013890:Thiourea