A thiol antioxidant regulates IgE isotype switching by inhibiting activation of nuclear factor-kappaB.
The binding site for nuclear factor-kappaB (NF-kappaB) is present at the promoter region of the germline Cepsilon gene, but there is little information on whether this factor is involved in regulating IgE synthesis by human B cells. Accordingly, we studied the role of NF-kappaB in germline Cepsilon transcription by using two human Burkitt's lymphoma B cell lines, DND39 and DG75. In both cell lines, n-acetyl-L-cysteine (NAC), a potent thiol antioxidant, inhibited the triggering of the nuclear expression of NF-kappaB by IL-4 and by anti-CD40 monoclonal antibody. Although IL-4 activated signal transducers and activators of transcription (STAT) 6 in addition to NF-kappaB, NAC treatment or the transfection of decoy oligodeoxynucleotides for NF-kappaB or STAT6 only partly blocked IL-4-induced germline Cepsilon transcription. However, these two decoy oligodeoxynucleotides together almost completely abrogated IL-4-induced germline Cepsilon transcription. Of note, CD40-mediated enhancement of IL-4-driven germline Cepsilon transcription was markedly decreased by NAC or by a decoy oligodeoxynucleotide for NF-kappaB. The effect of NAC was also examined on deletional switch recombination underlying the isotype switch to IgE. NAC inhibited the generation of Smu/Sepsilon switch fragments in normal human B cells costimulated with IL-4 and anti-CD40 monoclonal antibody. It also abolished IL-4-induced upregulation of CD40 but promoted upregulation of CD23. These results suggest that coordination of NF-kappaB and STAT6 may be required for induction of germline Cepsilon transcription by IL-4, and that CD40-mediated NF-kappaB activation may be important in regulating both enhancement of germline Cepsilon transcription and class switching to IgE.
Yanagihara
Y
Y
Clinical Research Center for Allergy, National Sagamihara Hospital, Sagamihara City, Kanagawa, Japan.
Basaki
Y
Y
Kajiwara
K
K
Ikizawa
K
K
D000111:Acetylcysteine / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D001402:B-Lymphocytes / Q000378:metabolism*; D019013:CD40 Antigens / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D005803:Genes, Immunoglobulin; D005812:Genes, Switch; D006801:Humans; D007073:Immunoglobulin E / Q000235:genetics*; D015847:Interleukin-4 / Q000494:pharmacology; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D050800:STAT6 Transcription Factor; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
D000975:Antioxidants; D019013:CD40 Antigens; D016328:NF-kappa B; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D015534:Trans-Activators; D015847:Interleukin-4; D007073:Immunoglobulin E; D019869:Phosphatidylinositol 3-Kinases; D000111:Acetylcysteine