Regulation of type 2 nitric oxide synthase by type 1 interferons in macrophages infected with Leishmania major.
We recently reported that the infection of macrophages with Leishmania major led to the release of type 1 interferons (IFN-alpha /beta ). Moreover, at day 1 of infection of mice with L. major, IFN-alpha /beta was required for the expression of type 2 (inducible) NO synthase (NOS2 or iNOS) which, however, was restricted to a few macrophages in the dermis. Here, we further characterized the regulation of NOS2 by IFN-alpha /beta. Macrophages that were either simultaneously or sequentially exposed to L. major promastigotes and IFN-alpha /beta expressed NOS2 and anti-leishmanial activity. In contrast, when high amounts of IFN-alpha /beta were used or when IFN-alpha /beta was added to the macrophages 2 h prior to the parasites, almost no induction of NOS2 was observed. After pretreatment with IFN-alpha /beta, tyrosine phosphorylation and nuclear DNA binding of Stat1alpha, the degradation of the NF-kappaB inhibitor (IkappaBalpha and beta), and the nuclear translocation of NF-kappaB were strongly impaired compared with macrophages exposed to IFN-alpha /beta and L. major simultaneously. Thus, IFN-alpha /beta exerts agonistic or antagonistic effects on the expression of NOS2 in macrophages infected with a microbial pathogen, depending on the sequence of the stimuli and the amount of IFN-alpha /beta added. The limited number of NOS2-positive macrophages at day 1 of infection in vivo might result from a blockage of non-infected macrophages by IFN-alpha /beta that is released by neighboring infected cells.
Institute of Clinical Microbiology, Immunology, and Hygiene, University of Erlangen, Erlangen, Germany.
J
J
Mattner
H
H
Schindler
A
A
Diefenbach
M
M
Röllinghoff
I
I
Gresser
C
C
Bogdan
D000818:Animals; D004268:DNA-Binding Proteins / Q000502:physiology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D007370:Interferon Type I / Q000494:pharmacology*; D018320:Leishmania major / Q000276:immunology*; D008264:Macrophages / Q000201:enzymology* / Q000469:parasitology; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000502:physiology; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II; D010766:Phosphorylation; D050794:STAT1 Transcription Factor; D015534:Trans-Activators / Q000502:physiology; D014443:Tyrosine / Q000378:metabolism
D004268:DNA-Binding Proteins; D007370:Interferon Type I; D016328:NF-kappa B; D050794:STAT1 Transcription Factor; C494080:Stat1 protein, mouse; D015534:Trans-Activators; D009569:Nitric Oxide; D014443:Tyrosine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse