Background: Chronic lung disease (CLD) of prematurity is an inflammatory disease with multifactorial etiology. The importance of Ureaplasma urealyticum in the development of CLD is debated. Steroids produce some improvement in neonates with this disease. We studied the potentials for U. Urealyticum to induce an inflammatory response.
Methods: A rat alveolar macrophage cell line (ATCC 8383) and heat killed U. Urealyticum serotype standard strain 8 were used. Griess reaction was used to analyse NO, western blot and RT-PCR to study iNOS protein and mRNA, EMSA to study NF-kB and immunostaining for localization of NF-kB and iNOS.
Results: We found that U. urealyticum antigen stimulated alveolar macrophages to produce NO in a dose and time dependent manner (p<0.05). This was attenuated by budesonide and dexamethasone (p<0.05). mRNA and protein levels of iNOS were also induced in response to U. Urealyticum and inhibited by steroids. U. urealyticum antigen triggered NF-kB activation, a possible mechanism responsible for the iNOS expression. NO induced by U. urealyticum caused a 6 fold reduction of its own growth after 10 h infection.
Conclusion: Our findings suggest that U. urealyticum may be important in the development of CLD. The host defense against U.urealyticum infection may also be influenced by NO. The down-regulatory effect of steroids on NF-kB activation, iNOS expression and NO production can partly explain steroids beneficial effect in CLD.