Ureaplasma isolates differentially modulate growth factors and cell adhesion molecules in human neonatal and adult monocytes

Abstract

Generally regarded as commensal bacteria, the pathogenicity of Ureaplasma has often been considered low. Controversy remains concerning the clinical relevance of Ureaplasma infection in the pathogenesis of inflammation-related morbidities. Recently, we demonstrated Ureaplasma-driven pro-inflammatory cytokine responses in human monocytes in vitro. We hypothesized that Ureaplasma may induce further inflammatory mediators. Using qRT-PCR and multi-analyte immunoassay, we assessed the expression of granulocyte-colony stimulating factor (G-CSF), vascular endothelial growth factor (VEGF), intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) in term neonatal and adult monocytes exposed to Ureaplasma urealyticum serovar 8 (Uu8) and U. parvum serovar 3 (Up3). Ureaplasma significantly induced VEGF mRNA in neonatal (Up3: p < 0.05, versus broth control) and adult monocytes (Uu8: p < 0.05) as well as ICAM-1 mRNA in neonatal cells (p < 0.05 each). As far as protein expression was concerned, Up3 stimulated VEGF release in both monocyte subsets (p < 0.01) and enhanced secretion of ICAM-1 protein in neonatal monocytes (p < 0.05). In adult cells, ICAM-1 protein release was increased upon exposure to both isolates (Uu8: p < 0.05, Up3: p < 0.01). Ureaplasma-induced responses did not significantly differ from corresponding levels mediated by E. coli lipopolysaccharide (LPS). The stimulatory effects were dose-dependent. Ureaplasma infection, on the contrary, did not affect G-CSF and VCAM-1 expression. Of note, co-infection of LPS-primed neonatal monocytes with Ureaplasma enhanced LPS-induced ICAM-1 release (Uu8: p < 0.05). Our results confirm Ureaplasma-driven pro-inflammatory activation of human monocytes in vitro, demonstrating a differential modulation of growth factors and cell adhesion molecules, that might promote unbalanced monocyte responses and adverse immunomodulation.