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Keywords:

  • COX-2;
  • HIV;
  • inflammation;
  • genital;
  • prostaglandin;
  • TLRs

Problem

Mucosal inflammation caused by infections of the female lower genital tract is considered to be an important cofactor for HIV transmission. We hypothesize that COX-2, a key inflammation-related enzyme, is involved in these responses and is upregulated by microbial ligands and pro-inflammatory cytokines.

Method of study

Human vaginal epithelial cells (VK-2/E6E7) and ectocervical biopsy tissues were stimulated with TLR ligands and the cytokine TNF-α, used as surrogates of vaginal infections, and assessed for COX-2 expression and activity by microarray, real-time RT-PCR, immunoblotting, immunohistochemistry, and ELISA.

Results

TLR agonists and TNF-α induce transcriptional and translational expression of COX-2 in vaginal cells. TLR ligands, MALP2, Pam3CSK4, LTA, and imiquimod induced high epithelial COX-2 expression, while zymosan and poly dI:dC induced very low enzyme expression. Induced mRNA and protein expression correlated with increased COX-2 activity, which led to increased levels of PGE2 in the cell culture supernatant. These cell-based findings were confirmed in primary cervicovaginal tissue explants.

Conclusion

Induction of COX-2 expression and activity and the consequent increased levels of prostaglandins are common inflammatory pathways in human cervicovaginal epithelial cells and tissues in response to diverse TLR ligands and pro-inflammatory cytokines. These findings are relevant to the understanding of genital mucosal inflammation, its potential treatment, and its possible relationship with increased tissue susceptibility to HIV-1 infection.