TH-17 cells in rheumatoid arthritis.
BACKGROUND
The aim of this study was to quantify the number of T-helper (TH)-17 cells present in rheumatoid arthritis (RA) synovial fluid (SF) and to determine the level of interleukin (IL)-17 cytokine in RA, osteoarthritis (OA) and normal synovial tissue, as well as to examine SF macrophages for the presence of IL-23, IL-27 and interferon (IFN)-gamma.


METHODS
Peripheral blood (PB) mononuclear cells from normal and RA donors and mononuclear cells from RA SF were examined either without stimulation or after pretreatment with IL-23 followed by stimulation with phorbol myristate acetate (PMA) plus ionomycin (P/I). The abundance of TH-17 cells in RA SF was determined by flow cytometry. IL-17 levels were quantified in synovial tissue from RA, OA and normal individuals by ELISA and IL-23 was identified in SFs by ELISA. RA SF and control in vitro differentiated macrophages were either untreated or treated with the toll-like receptor (TLR) 2 ligand peptidoglycan, and then IL-23, IL-27 and IFN-gamma mRNA levels were quantified by real-time polymerase chain reaction (RT-PCR).


RESULTS
Treatment with P/I alone or combined with IL-23 significantly increased the number of TH-17 cells in normal, RA PB and RA SF. With or without P/I plus IL-23, the percentage of TH-17 cells was higher in RA SF compared with normal and RA PB. IL-17 levels were comparable in OA and normal synovial tissues, and these values were significantly increased in RA synovial tissue. Although IL-17 was readily detected in RA SFs, IL-23 was rarely identified in RA SF. However, IL-23 mRNA was significantly increased in RA SF macrophages compared with control macrophages, with or without TLR2 ligation. IL-27 mRNA was also significantly higher in RA SF compared with control macrophages, but there was no difference in IL-27 levels between RA and control macrophages after TLR2 ligation. IFN-gamma mRNA was also detectable in RA SF macrophages but not control macrophages and the increase of IFN-gamma mRNA following TLR2 ligation was greater in RA SF macrophages compared with control macrophages.


CONCLUSIONS
These observations support a role for TH-17 cells in RA. Our observations do not strongly support a role for IL-23 in the generation of TH-17 cells in the RA joint, however, they suggest strategies that enhance IL-27 or IFN-gamma might modulate the presence of TH-17 cells in RA.
Shahrara
Shiva
S
Department of Medicine, Feinberg School of Medicine, Northwestern University 240 E Huron, Chicago, IL 60611, USA. s-shahrara@northwestern.edu
Huang
Qiquan
Q
Mandelin
Arthur M
AM
Pope
Richard M
RM
D001172:Arthritis, Rheumatoid / Q000209:etiology* / Q000378:metabolism / Q000473:pathology*; D002273:Carcinogens / Q000494:pharmacology; D016022:Case-Control Studies; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D020381:Interleukin-17 / Q000378:metabolism*; D053759:Interleukin-23 / Q000378:metabolism; D007378:Interleukins / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D013582:Synovial Fluid / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D006377:T-Lymphocytes, Helper-Inducer / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D002273:Carcinogens; D020381:Interleukin-17; D053759:Interleukin-23; D007378:Interleukins; D007476:Ionophores; C464565:MYDGF protein, human; D012333:RNA, Messenger; D015759:Ionomycin; D007371:Interferon-gamma; D013755:Tetradecanoylphorbol Acetate