Background The involvement of natural antimicrobial peptides in infection-associated preterm birth is unknown. Our aim was to assess regulation by granulocyte-macrophage colony-stimulating factor, monocyte-chemotactic-protein-1 (GM-CSF and MCP-1, interleukin-1 (IL) and lipopolysaccharide (LPS) in cultured human vaginal epithelial cells.

Methods VK2/E6E7 cells were treated with IL-1, MCP-1 and GM-CSF (20/100/200/500 pg/ml and 1 ng/ml) at 2 h, 4 h, 6 h and 24 h (n=4). Cells (n=3–4) were also treated with MCP-1, IL-1 (1 ng/ml or 10 ng/ml) or LPS (50 ng/ml or 100 ng/ml) for 6 h or 24 h. mRNA was extracted and assessed SLPI, SKALP, HBD1 and HBD2 by qPCR. Data was analysed by ANOVA with repeated measures.

Results SLPI, SKALP and HBD1–2 transcripts were identified in VK2/E6E7 cells. 100 ng/ml IL-1 increased SKALP mRNA expression at 2 h (p=0.005) and 1 ng/ml at 4 h and 6 h (p=0.0003).Expression was maintained at 24 h with 10 ng/ml (p=0.0002). GM-CSF (100 pg/ml) suppressed SKALP mRNA expression after 24 h (p=0.005). 1 ng/ml and 10 ng/ml IL-1 increased HBD2 mRNA expression at 6 h (p=0.003) being maintained at 24 h with 10 ng/ml IL-1 (p=0.0002). LPS (100 ng/ml) increased SKALP mRNA expression at 6 h and 24 h (p<0.05).

Conclusions This data shows NAs expression and regulation by inflammatory agents in VK2/E6E7 cells. GM-CSF suppression of SKALP, at concentrations found in cervico-vaginal fluid, provides a novel mechanism by which impaired immune defences against ascending infection in women at risk of preterm labour.