INVERSE GENE-EXPRESSION OF PROSTACYCLIN AND THROMBOXANE SYNTHASES IN RESIDENT AND ACTIVATED PERITONEAL-MACROPHAGES

Prostacyclin and thromboxane A(2) produced from prostaglandin Hz are k nown to be important modulators with opposite biological activities. T o examine possible roles of these prostanoids in immune responses, we have studied the gene expression of prostacyclin synthase (PGIS) and t hromboxane synthase (TXS) in murine resident macrophages or in macroph ages elicited with casein or bacillus Calmette-Gauerin (BCG). Northern blot analyses showed that the PGIS mRNA was expressed in a decreasing order in the resident, and casein- and BCG-elicited macrophages. In c ontrast, the TXS mRNA was expressed in an increasing order in the resi dent, and casein- and BCG-elicited macrophages. On the other hand, the mRNA for cyclooxygenase-2, which produces PGH(2) and participates in the production of prostanoids in inflammation, was expressed in both t he resident and BCG-elicited macrophages but barely in the casein-elic ited cells, In situ hybridization analysis showed that the expression of mRNAs for PGIS and TXS was ascribable not only to the alteration of the expression levels of both mRNAs in the each macrophage but also t o the changes in subpopulations of the cells expressing these mRNAs. T hese observations suggested that the inverse gene expression of PGIS a nd TXS in macrophages contributes to immune responses by modulating th e relative levels of prostacyclin and thromboxane A(2). (C) 1997 Feder ation of European Biochemical Societies.