Interleukin-15 stimulates macrophages to activate CD4+ T cells: a role in the pathogenesis of rheumatoid arthritis?
Immunology
; 126(1): 63-73, 2009 Jan.
Article
em En
| MEDLINE
| ID: mdl-18557790
ABSTRACT
Interleukin-15 (IL-15) is a proinflammatory cytokine that is overexpressed in rheumatoid arthritis (RA), a disease characterized by activation of monocytes/macrophages (MPhi), and by expansion of autoreactive CD4(+) T cells. We hypothesized that IL-15 plays a major role for this expansion of CD4(+) T cells and modulates the phenotype of monocytes/MPhi and their interaction with CD4(+) T cells. Here, we show that IL-15 enhances the proliferation of CD4(+) T cells from patients with RA in peripheral blood mononuclear cell cocultures. To further dissect the underlying mechanisms, we employed MPhi from IL-15(-/-) or IL-15 transgenic mice. These were induced to differentiate or were stimulated with IL-15. Here we show that addition of IL-15 during differentiation of MPhi (into 'IL-15MPhi') and overexpression of IL-15 by MPhi from IL-15(tg) mice leads to increased levels of major histocompatibility complex class II expression. This resulted in enhanced stimulation of antigen-specific CD4(+) T cells in vitro and was accompanied by reduced messenger RNA expression in MPhi for immunosuppressive SOCS3. The proliferation rates of IL-15MPhi and IL-15(tg)MPhi were high, which was reflected by increased p27(Kip1) and reduced p21(Waf1) levels. In view of high serum and synovial levels of IL-15 in patients with RA, our data suggest the possibility that this excess IL-15 in RA may stimulate monocytes/MPhi to activate the characteristic autoreactive CD4(+) T cells in RA.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Artrite Reumatoide
/
Linfócitos T CD4-Positivos
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Interleucina-15
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Macrófagos
Tipo de estudo:
Etiology_studies
Limite:
Aged
/
Animals
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Female
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Humans
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Male
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Middle aged
Idioma:
En
Ano de publicação:
2009
Tipo de documento:
Article