Ureaplasma urealyticum-induced production of proinflammatory cytokines by macrophages

Ureaplasma urealyticum is relatively common in the respiratory tract of ver y low birth weight infants and has been hypothesized to be involved in the development of chronic lung disease. The purpose of this study was to inves tigate whether U. urealyticum could stimulate macrophages to produce proinf lammatory cytokines in vitro, which are early pathologic changes in the lun g during the development of chronic lung disease. A human monocytic cell li ne (THP-1) differentiated to macrophages, a rat alveolar macrophage cell li ne (M8383), and human lung macrophages from tracheobronchial aspirate fluid in preterm infants were exposed to U. urealyticum antigen for 24 h. The pr otein levels of human IL-6, tumor necrosis factor-alpha (TNF-alpha), and ra t TNF-alpha were measured with ELISA. Rat IL-6 was analyzed with a specific bioassay. The mRNA levels of these cytokines were detected by reverse tran scriptase-PCR. The production of TNF-alpha and IL-6 increased after stimula tion with U. urealyticum in both the human and rat macrophage cell lines. I n tracheobronchial aspirate fluid macrophages, U, Mrenlyticum increased the production of TNF-alpha from 14 to 84% and IL-6 from 46 to 268% above cont rol levels. LI. urenlyticum also induced gene expression of TNF-alpha and I L-6. In conclusion, U. urealyticum could be an important factor in the deve lopment of chronic lung disease because of its ability to induce alveolar m acrophage proinflammatory cytokine production.