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  • Anti-ribosomal phosphoprotein autoantibody triggers interleukin-10 overproduction via phosphatidylinositol 3-kinase-dependent signalling pathways in lipopolysaccharide-activated macrophages.

Anti-ribosomal phosphoprotein autoantibody triggers interleukin-10 overproduction via phosphatidylinositol 3-kinase-dependent signalling pathways in lipopolysaccharide-activated macrophages.

Immunology (2008-09-10)
Tai-Ping Lee, Shr-Jeng Jim Leu, Jason C Huang, Ying-Chyi Song, Ren-Shiang Jhou, Shye-Jye Tang, Kuang-Hui Sun
ABSTRACT

Anti-ribosomal phosphoprotein autoantibodies have been shown to be significantly associated with multiple manifestations of systemic lupus erythematosus (SLE). High levels of interleukin-10 (IL-10) have been demonstrated to contribute to lupus susceptibility and severity. In this study, we investigated the molecular mechanisms of anti-ribosomal phosphoprotein monoclonal antibody (anti-P mAb)-induced autoimmune responses. Anti-P mAb promoted IL-10 overproduction in a dose- and time-dependent manner in both lipopolysaccharide (LPS)-activated RAW 264.7 cells and primary human macrophages. Anti-P mAb enhanced phosphorylation of Akt (PKB; protein kinase B), extracellular signal regulated kinase 1/2 (ERK1/2) and c-Jun NH2-terminal kinase 1/2 (JNK1/2), while phosphorylation of p38 remained unaltered. Furthermore, anti-P mAb decreased glycogen synthase kinase 3 (GSK3) activity and reduced the phosphorylation of I kappaB alpha in LPS-activated macrophages. The Syk, phosphatidylinositol 3-kinase (PI3K), protein kinase C (PKC), JNK and ERK signalling pathways involved in anti-P mAb-triggered IL-10 secretion were also confirmed using various pharmacological inhibitors. In addition, nuclear factor (NF)-kappaB had negative regulatory effects on anti-P mAb-triggered IL-10 secretion. Using reporter plasmids containing the nuclear factor binding sites of NF-kappaB, cAMP-enhanced activation protein 1 (AP-1), serum response element (SRE) or cyclic AMP response element (CRE), treatment of anti-P mAb led to activation of the corresponding factors that bind to the AP-1 site, SRE and CRE in the LPS-activated macrophages. Furthermore, by transfection with reporter plasmids bearing various lengths of the IL-10 promoter, the AP-1 binding site, SRE and CRE were shown to be required for anti-P mAb-induced effects. Collectively, our results provide a molecular model for anti-P mAb-induced IL-10 overproduction in LPS-activated macrophages, which may play a role in the pathogenesis of SLE.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Lipopolysaccharides from Escherichia coli O26:B6, purified by gel-filtration chromatography
Sigma-Aldrich
Lipopolysaccharides from Escherichia coli O26:B6, γ-irradiated, BioXtra, suitable for cell culture
Sigma-Aldrich
Lipopolysaccharides from Escherichia coli O26:B6, purified by trichloroacetic acid extraction
Sigma-Aldrich
Lipopolysaccharides from Escherichia coli O26:B6, ≥10,000 EU/mg, purified by phenol extraction
Sigma-Aldrich
Lipopolysaccharides from Escherichia coli O26:B6, Ready Made solution, 1 mg/mL, 0.2 μm filtered
Sigma-Aldrich
Polymyxin B-Agarose, aqueous glycerol suspension