IL-17A- versus IL-17F-induced intracellular signal transduction pathways and modulation by IL-17RA and IL-17RC RNA interference in rheumatoid synoviocytes.
OBJECTIVE
The aim of this study was to compare the effects of interleukin (IL)-17A and IL-17F on gene expression and signalling in human rheumatoid arthritis (RA) synoviocytes.


METHODS
IL-17A- and IL-17F-induced mRNA expression was analysed using Affymetrix microarrays. IL-6 and IL-8 secretion was evaluated by ELISA. Inhibition of two receptors (IL-17RA and IL-17RC) was achieved by small interfering RNA (saran). The effects on mitogen-activated protein kinase (MAPK), activator protein 1 (AP-1) and nuclear factor κB (NF-κB) expression and activation were evaluated by western blotting, qRT-PCR and DNA binding assay.


RESULTS
IL-17A and IL-17F induced a molecular pattern characterised by 27 inflammation-related genes for IL-17F and 165 for IL-17A. Virtually all IL-17A and IL-17F inducible genes were dependent on NF-κB activation, whereas a small number were modulated by p38. IL-17A induced activation of all three MAPKs (ERK, p38 and JNK) and downstream transcription factors AP-1 and p65 NF-κB. IL-17F was less potent but induced activation of p50 NF-κB. IL-17A was more potent at inducing IL-6 secretion than IL-17F, which was inactive alone. IL-17A and, to a lesser extent, IL-17F induced TRAF6 but not MyD88. Inhibition of either IL-17RA or IL-17RC expression via siRNA led to near complete abrogation of IL-6 expression mediated by IL-17A and the combination of IL-17F and tumour necrosis factor α.


CONCLUSIONS
Like IL-17A, IL-17F regulates proinflammatory gene expression by a very similar but not identical signalling pathway involving IL-17RA and IL-17RC.
Clinical Immunology Unit, Department of Immunology and Rheumatology, Hospital Edouard Herriot, France. pierre.miossec@univ-lyon1.fr
Arnaud
A
Hot
Saloua
S
Zrioual
Myew-Ling
ML
Toh
Vanina
V
Lenief
Pierre
P
Miossec
D001172:Arthritis, Rheumatoid / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D020869:Gene Expression Profiling / Q000379:methods; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques / Q000379:methods; D006801:Humans; D020381:Interleukin-17 / Q000494:pharmacology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics; D018123:Receptors, Interleukin / Q000235:genetics / Q000502:physiology; D053722:Receptors, Interleukin-17 / Q000235:genetics / Q000502:physiology; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013583:Synovial Membrane / Q000378:metabolism* / Q000473:pathology; D014157:Transcription Factors / Q000378:metabolism
C440021:IL17F protein, human; C109985:IL17RA protein, human; C448419:IL17RC protein, human; D020381:Interleukin-17; D012333:RNA, Messenger; D018123:Receptors, Interleukin; D053722:Receptors, Interleukin-17; D011994:Recombinant Proteins; D014157:Transcription Factors; D020929:Mitogen-Activated Protein Kinase Kinases