Hydrogen peroxide inhibits IL-12 p40 induction in macrophages by inhibiting c-rel translocation to the nucleus through activation of calmodulin protein.
Although the antimicrobial activity of reactive oxygen species (ROSs) is well defined, the role of ROSs in regulating the immune response of the body is not well understood. We now provide evidence that hydrogen peroxide (H2O2), a major component of ROSs, inhibits interleukin-12 (IL-12) p40 and IL-12 p70 induction in murine macrophages and catalase pretreatment prevents H2O2-mediated down-regulation of IL-12. Endogenous accumulation of H2O2/ROSs in macrophages treated with alloxan resulted in IL-12 p40 inhibition. Although nuclear expression of both p50 and p65 NF-kappaB increased on H2O2 exposure, nuclear c-rel level was inhibited. Overexpression of c-rel restored IL-12 p40 on stimulation with lipopolysaccharide plus IFN-gamma during H2O2 treatment. H2O2 did not inhibit c-rel induction in cytosol; however, it prevented the transport of c-rel from cytosol to the nucleus. H2O2 activated calmodulin (CaM) protein in the cytosol, which subsequently sequestered c-rel in the cytosol preventing its transport to the nucleus. The CaM inhibitor trifIuoperazine increased both nuclear c-rel and IL-12 p40 levels in H2O2-treated macrophages, emphasizing a role of CaM in these processes. H2O2/ROSs thus down-regulate IL-12 induction in macrophages by a novel pathway inhibiting c-rel translocation to the nucleus through activation of CaM protein.
Khan
Nooruddin
N
Laboratory of Molecular and Cellular Biology, CDFD, Hyderabad, India.
Rahim
Sheikh Showkat
SS
Boddupalli
Chandra Sekhar
CS
Ghousunnissa
Sheikh
S
Padma
Samavedan
S
Pathak
Niteen
N
Thiagarajan
Dorairajan
D
Hasnain
Seyed E
SE
Mukhopadhyay
Sangita
S
D000818:Animals; D002147:Calmodulin / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D018664:Interleukin-12 / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000276:immunology; D053762:Interleukin-12 Subunit p40; D008264:Macrophages / Q000187:drug effects / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D021122:Protein Subunits / Q000096:biosynthesis / Q000187:drug effects / Q000276:immunology*; D021381:Protein Transport / Q000187:drug effects; D020569:Proto-Oncogene Proteins c-rel / Q000378:metabolism*; D014268:Trifluoperazine / Q000494:pharmacology
D002147:Calmodulin; D053762:Interleukin-12 Subunit p40; D021122:Protein Subunits; D020569:Proto-Oncogene Proteins c-rel; D018664:Interleukin-12; D014268:Trifluoperazine; D006861:Hydrogen Peroxide