Increased expression of CCL18, CCL19, and CCL17 by dendritic cells from patients with rheumatoid arthritis, and regulation by Fc gamma receptors.
BACKGROUND
Dendritic cells (DC) have a role in the regulation of immunity and tolerance, attracting inflammatory cells by the production of various chemokines (CK). Fc gamma receptors (Fc gamma R) may be involved in regulation of the DC function.


OBJECTIVE
To assess the expression of CK by immature (iDC) and mature DC (mDC) and its regulation by Fc gamma R in patients with RA and healthy donors (HC).


METHODS
Expression of CK by DC from patients with RA and from HC was determined by real time quantitative PCR and ELISA. DC were derived from monocytes following standardised protocols. To study the potential regulation by Fc gamma R, iDC were stimulated with immune complexes (IC) during lipopolysaccharide (LPS) induced maturation. The presence of CK was studied in synovial tissue from patients with RA, osteoarthritis, and healthy subjects by RT-PCR and immunohistochemistry.


RESULTS
iDC from patients with RA had markedly increased mRNA levels of the CK CCL18 and CXCL8. Upon maturation with LPS, expression of CCL18, CCL19, CXCL8, CCL3, and CCL17 increased dramatically, reaching significantly higher levels in patients with RA. Monocytes failed to express these CK, except for CXCL8 and CCL3. IC-mediated triggering of the Fc gamma R on DC from patients with highly active RA down regulated all CK, whereas the reverse was seen when DC from patients with low disease activity and healthy donors were stimulated. CCL18 was significantly increased in RA synovial tissue.


CONCLUSIONS
Increased CK expression by DC was found in patients with RA. This expression is partly regulated by Fc gamma R triggering and results in an inhibitory DC subtype in RA upon Fc gamma R-mediated triggering.
Radstake
T R D J
TR
Department of Rheumatology, University Medical Centre Nijmegen, The Netherlands. T.Radstake@reuma.umcn.nl
van der Voort
R
R
ten Brummelhuis
M
M
de Waal Malefijt
M
M
Looman
M
M
Figdor
C G
CG
van den Berg
W B
WB
Barrera
P
P
Adema
G J
GJ
D001172:Arthritis, Rheumatoid / Q000097:blood*; D002478:Cells, Cultured; D054414:Chemokine CCL17; D054415:Chemokine CCL19; D019742:Chemokines, CC / Q000096:biosynthesis / Q000097:blood* / Q000235:genetics; D003713:Dendritic Cells / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D009000:Monocytes / Q000378:metabolism; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000235:genetics; D017452:Receptors, IgG / Q000502:physiology*; D012720:Severity of Illness Index; D013583:Synovial Membrane / Q000378:metabolism
C106230:CCL17 protein, human; C111792:CCL18 protein, human; C515460:CCL19 protein, human; D054414:Chemokine CCL17; D054415:Chemokine CCL19; D019742:Chemokines, CC; D012333:RNA, Messenger; D017452:Receptors, IgG