INFECTION OF BOVINE BRAIN MICROVESSEL ENDOTHELIAL-CELLS WITH COWDRIA-RUMINANTIUM ELICITS IL-1-BETA, IL-6, AND IL-8 MESSENGER-RNA PRODUCTIONAND EXPRESSION OF AN UNUSUAL MHC CLASS-II DQ-ALPHA TRANSCRIPT

Cowdria ruminantium is a bacterial parasite that infects ruminants, ca using an acute and often fatal disease. These obligate intracellular G ram-negative bacteria preferentially infect neutrophils and vascular e ndothelial cells, especially in the brain. The present study was perfo rmed with bovine brain microvessel endothelial cells in culture, infec ted by C. ruminantium in the presence or absence of IFN-gamma. Infecti on induced the production of IL-1 beta, -6, and -8. mRNAs, and this ef fect was potentiated by IFN-gamma. A semi-quantitative PCR analysis in dicated that similar amounts of IL-1 beta and IL-6 mRNAs were produced in response to C. ruminantium infection and to treatment with 30 to 4 0 ng/ml LPS. In addition, although IFN-gamma induced the synthesis of an MHC class II DQ alpha transcript (1.3 kb), an unusual transcript (1 .5 kb) was induced by infection and not after LPS treatment. Infection did not affect MHC class I, class II DQ beta, and invariant chain mRN A levels. The present results suggest that C. ruminantium infection ra ises the immune activity of brain endothelial cells in vitro and that only part of this response can be attributed to LPS. One can hypothesi ze that cerebral endothelium in vivo efficiently contributes, by MHC A g expression and production of ILs, to the activation and/or recruitme nt of leukocytes to the brain and thus plays an active role in the pat hogenesis of cowdriosis and in the immune response to this pathogen.