1. ¹Department of CardioRenal and Cerebrovascular Medicine, Faculty of Medicine, Kagawa University, Kagawa, Japan
2. ²Department of Pharmacology, Faculty of Medicine, Kagawa University, Kagawa, Japan
3. ³NTT West Takamatsu Clinic, Kagawa, Japan

Correspondence: H Kiyomoto, Department of CardioRenal and Cerebrovascular Medicine, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki, Kita-gun, Kagawa 761-0793, Japan. E-mail: kiyo@med.kagawa-u.ac.jp

Received 2 December 2005; Revised 3 May 2006; Accepted 9 May 2006; Published online 5 July 2006.

Abstract

Immune reactive cytokines, such as interferon (IFN)-, have multiple effects in glomerulonephritis. Superoxide anions (O₂^-), which are associated with the progression of glomerulonephritis, are mainly generated by nicotinamide adenine dinucleotide phosphate (reduced form) NAD(P)H oxidases. We determined the effects of IFN- on O₂^- production, phosphorylation of signal transducer and activator of transcription (STAT)-1, and the mRNA and protein expressions of p22phox and Nox1, components of NAD(P)H oxidases, in human mesangial cells (HMCs). Significant increases in O₂^- production with IFN- were completely abolished by the flavin-containing enzyme inhibitor, diphenyleneiodonium (10 mol/l), and the Janus-activated kinase (JAK)2 inhibitor, AG490 (100 mol/l). Phosphorylated STAT-1 was detected after 5 min of IFN- stimulation using Western blot analysis, and binding to the gamma-activating site was observed from 30 min to 4 h, thereafter by electrophoretic mobility shift assay (EMSA). Super-shift analysis in EMSA revealed that the main transcription factor was STAT-1. IFN- significantly increased the expression of p22phox mRNA and protein, although expression was inhibited by AG490. These data suggest that IFN- stimulates O₂^- production in HMCs via the JAK–STAT pathway and NAD(P)H oxidase.