Induction of monocyte chemoattractant protein-1 by Mycoplasma hominis in respiratory epithelial cells.

Background: Very small preterm infants who have genital mycoplasmas isolated from the trachea are at increased risk to develop bronchopulmonary dysplasia (BPD). The early stages of BPD are characterized by inflammation. Recruitment and activation of mononuclear cells in response to mycoplasmas may be important in the early stage of the disease. Lung epithelial cell production of monocyte chemoattractant protein-1 (MCP-1), a protein that attracts and activates mononuclear cells, could be critical in the regulation of mononuclear cell migration to the lung.
Methods: We examined the potential of Mycoplasma hominis (Mh) to induce MCP-1 gene expression and protein production in A549 cells, a pulmonary epithelial cell line with characteristics of type II cells.
Results: Live or heat-inactivated Mh induces MCP-1 mRNA and protein in a dose- and time-dependent manner. Stimulation of MCP-1 by Mh was not inhibited by 50 micrograms/mL of polymyxin B, interleukin (IL)-1ra, or neutralizing antibodies to IL-1 alpha, IL-1 beta, or tumor necrosis factor alpha (TNF-alpha). IL-1 alpha, IL-1 beta, and TNF-alpha were not detected in conditioned media of Mh-stimulated A549 cells.
Conclusions: These data suggest that Mh may participate in the inflammatory component of BPD by directly inducing epithelial cell production of cytokines that recruit and activate mononuclear cells.