Disruption of Tight Junctions by Cellulose Sulfate Facilitates HIV Infection: Model of Microbicide Safety

Abstract

Background The lack of biomarkers that are predictive of safety is a critical gap in the development of microbicides. The present experiments were designed to evaluate the predictive value of in vitro models of microbicide safety. Methods Changes in the epithelial barrier were evaluated by measuring transepithelial electrical resistance (TER) after exposure of human epithelial cells to candidate microbicides in a dual-chamber system. The significance of observed changes was addressed by challenging cultures with human immuodeficiency virus (HIV) and measuring the ability of virus to cross the epithelium and infect target T cells cultured in the lower chamber. Results Exposure to nonoxynol-9 (N-9) or cellulose sulfate (CS), but not 9-[2-(phosphonomethoxy)propyl]adenine (also referred to as tenofovir) or PRO2000, resulted in a rapid and sustained reduction in TER and a marked increase in HIV infection of T cells cultured in the lower chamber. Moreover, CS triggered nuclear factor κB activation in peripheral blood mononuclear cells and increased HIV replication in chronically infected U1 cells. Conclusions Epithelial barrier disruption and enhanced viral replication may have contributed to the increased risk of HIV acquisition observed in phase 3 trials of N-9 and CS. Expansion of in vitro safety testing to include these models would provide a more stringent preclinical assessment of microbicide safety and may prove to be more predictive of clinical outcomes.

The Cholestanol-Conjugated Sulfated Oligosaccharide PG545 Disrupts the Lipid Envelope of Herpes Simplex Virus Particles

“…It should be noted that prophylactic application of PG545 and sulfated oligosaccharides as vaginal microbicides requires relatively high concentrations of these compounds. This requirement is most likely due to the neutralization of the compounds by different GAG-binding proteins (22) of the genital mucosa, such as epithelium-and neutrophil-derived antimicrobial polypeptides and components of seminal plasma (49) and cervical secretions (27), as well as some extracellular matrix and cell adhesion proteins (57). This implies that besides neutralization of an inhibitor, these interactions may impair local innate and adaptive immunity and perturb the structural integrity of the epithelium (57), i.e., alterations that most likely contributed to the failure of GAG mimetics in HIV clinical trials.…”

In Vitro Evaluation of Viability, Integrity, and Inflammation in Genital Epithelia upon Exposure to Pharmaceutical Excipients and Candidate Microbicides

“…Several in vitro and ex vivo models are currently being explored (5,11,13,15,19,22,27,34). In vitro assays have the advantage that they are quick and sensitive and can be used for high-throughput screening in early discovery and development.…”

“…However, the subsequent phase III trial was closed prematurely due to a nonsignificantly higher incidence of HIV infections in the treated arm than in the placebo arm (20). To date, it is unclear whether or not the failure of CS in the clinical trial was a result (27). This raises the question whether the evaluations performed in phase I clinical trials are sensitive enough to predict the safety outcomes for microbicides.…”

Herpes Simplex Virus Type 2 Infection of Human Epithelial Cells Induces CXCL9 Expression and CD4+ T Cell Migration via Activation of p38-CCAAT/Enhancer-Binding Protein-β Pathway

“…Several mechanisms for this increased susceptibility have been proposed. For instance, the formation of pustules and ulcers by genital herpes may facilitate HIV-1 entry into mucosal tissues (10,11). Analyses of biopsies of HSV-2 lesions from patients revealed that HSV-2 reactivation resulted in an influx of activated CD4 + T cells, which may facilitate HIV-1 infection and subsequent dissemination (12,13).…”