Since epithelial cells are important in the recruitment of inflammatory cells into the airways, we sought to investigate whether mycoplasma antigens could induce interleukin (IL)-8, a potent chemokine for neutrophils. Cultured BEAS-2B human bronchial epithelial cells stimulated with mycoplasma membrane fraction (MMF) increased IL-8 production in a dose-dependent fashion (Fig 1
). Stimulation of the BEAS-2B cells with 10 ng/mL of lipopolysaccharide or with MMF plus 10 μmol/L polymyxin B demonstrated that the ability of MMF to induce IL-8 was not due to contaminating lipopolysaccharide (data not shown). In addition, MMF activated nuclear factor-κB, a transcription factor known to bind to a κB cis-element on the 5′-flanking region of the IL-8 promoter. Inhibition of nuclear factor-κB activation with an IκBα-kinase inhibitor (BAY11–7082) resulted in significant inhibition of MMF-induced IL-8 protein expression. MMF also activated all three isoforms of the mitogen-activated protein kinases. Co-culture of MMF-stimulated BEAS-2B cells with inhibitors of the mitogen-activated protein kinase pathways revealed that these serine-threonine kinases modulate MMF-induced IL-8 expression in a complex fashion. In conclusion, these findings show that mycoplasma antigens are able to induce IL-8 production in human airway epithelial cells. We hypothesize that infection with these organisms may play a role in the pathogenesis of the neutrophilic response that characterizes many cases of severe asthma.