Catalytically inactive cyclooxygenase 2 and absence of prostaglandin E2 biosynthesis in murine peritoneal macrophages following in vivo phagocytosis of heat-killed Mycobacterium bovis bacillus Calmette-Guérin.
Over 25 years ago, it was observed that peritoneal macrophages (Mphi) isolated from mice given heat-killed Mycobacterium bovis bacillus Calmette-Guérin (HK-BCG) i.p. did not release PGE(2). However, when peritoneal Mphi from untreated mice are treated with HK-BCG in vitro, cyclooxygenase 2 (COX-2), a rate-limiting enzyme for PGE(2) biosynthesis, is expressed and the release of PGE(2) is increased. The present study of peritoneal Mphi obtained from C57BL/6 mice and treated either in vitro or in vivo with HK-BCG was undertaken to further characterize the cellular responses that result in suppression of PGE(2) release. The results indicate that Mphi treated with HK-BCG in vivo express constitutive COX-1 and inducible COX-2 that are catalytically inactive, are localized subcellularly in the cytoplasm, and are not associated with the nuclear envelope (NE). In contrast, Mphi treated in vitro express catalytically active COX-1 and COX-2 that are localized in the NE and diffusely in the cytoplasm. Thus, for local Mphi activated in vivo by HK-BCG, the results indicate that COX-1 and COX-2 dissociated from the NE are catalytically inactive, which accounts for the lack of PGE(2) production by local Mphi activated in vivo with HK-BCG. Our studies further indicate that the formation of catalytically inactive COX-2 is associated with in vivo phagocytosis of HK-BCG, and is not dependent on extracellular mediators produced by in vivo HK-BCG treatment. This attenuation of PGE(2) production may enhance Mphi-mediated innate and Th1-acquired immune responses against intracellular infections which are suppressed by PGE(2).
Yamashita
Makiko
M
College of Biomedical Sciences, Florida Atlantic University, Boca Raton, FL 33431, USA.
Shinohara
Tsutomu
T
Tsuji
Shoutaro
S
Myrvik
Quentin N
QN
Nishiyama
Akihito
A
Henriksen
Ruth Ann
RA
Shibata
Yoshimi
Y
D000818:Animals; D002478:Cells, Cultured; D051545:Cyclooxygenase 1 / Q000276:immunology / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000276:immunology* / Q000378:metabolism; D003593:Cytoplasm / Q000201:enzymology / Q000276:immunology; D015232:Dinoprostone / Q000096:biosynthesis / Q000276:immunology*; D005260:Female; D007113:Immunity, Innate; D017737:Macrophages, Peritoneal / Q000201:enzymology / Q000276:immunology*; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism; D051379:Mice; D009163:Mycobacterium bovis / Q000276:immunology*; D009685:Nuclear Envelope / Q000201:enzymology / Q000276:immunology; D010587:Phagocytosis / Q000276:immunology*; D018417:Th1 Cells / Q000201:enzymology / Q000276:immunology*
D008565:Membrane Proteins; C077623:Ptgs2 protein, mouse; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496512:Ptgs1 protein, mouse; D015232:Dinoprostone