Foam cell formation inhibits growth of Chlamydia pneumoniae but does not attenuate Chlamydia pneumoniae-induced secretion of proinflammatory cytokines.
BACKGROUND
It has not yet been determined whether lipid-loaded macrophages (foam cells), a major cellular component of atherosclerotic lesions, have the capacity to support growth of Chlamydia pneumoniae and be activated to secrete proinflammatory cytokines in response to C pneumoniae infection.


RESULTS
Lipid loading of RAW 264.7 cells and mouse peritoneal macrophages with either oxidized or acetylated LDL significantly inhibits the growth of C pneumoniae. Modified forms of LDL are not directly toxic to C pneumoniae and do not inhibit either the initial binding or internalization of C pneumoniae by macrophages. Lipid loading does not reduce infection of macrophages with Chlamydia trachomatis. Treatment of lipid-loaded macrophages with live, heat-killed, or UV-inactivated C pneumoniae stimulates secretion of cytokines. C pneumoniae also induces expression of the mRNA for tumor necrosis factor-alpha in foam cells despite inhibition of nuclear factor-kappaB binding to DNA by prior treatment with oxidized LDL.


CONCLUSIONS
Foam cell formation is not conducive to growth of C pneumoniae but does not inhibit the C pneumoniae-induced secretion of proinflammatory cytokines.
Blessing
Erwin
E
Department of Pathobiology, University of Washington, Seattle 98195, USA.
Kuo
Cho-Chou
CC
Lin
Tsun-Mei
TM
Campbell
Lee Ann
LA
Bea
Florian
F
Chesebro
Brian
B
Rosenfeld
Michael E
ME
D000818:Animals; D001161:Arteriosclerosis / Q000382:microbiology; D002455:Cell Division; D002460:Cell Line; D002478:Cells, Cultured; D016993:Chlamydophila pneumoniae / Q000254:growth & development*; D002784:Cholesterol / Q000032:analysis; D016207:Cytokines / Q000096:biosynthesis* / Q000378:metabolism; D005487:Foam Cells / Q000737:chemistry / Q000276:immunology / Q000382:microbiology*; D008077:Lipoproteins, LDL / Q000494:pharmacology; D008264:Macrophages / Q000737:chemistry / Q000382:microbiology; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics
D016207:Cytokines; D008077:Lipoproteins, LDL; D016328:NF-kappa B; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C099252:oxidized low density lipoprotein; D002784:Cholesterol