Expression and regulation of cryopyrin and related proteins in rheumatoid arthritis synovium.
BACKGROUND
Rheumatoid arthritis (RA) synovium is characterised by enhanced NF-kappaB activity and proinflammatory cytokines. Cryopyrin (CIAS-1, NALP-3, PYPAF-1) has been shown to regulate NF-kappaB and caspase-1 activation.


OBJECTIVE
To study the expression of cryopyrin, its effector molecule ASC, and its putative antagonist pyrin in RA and osteoarthritis (OA) synovium, and the main two cellular constituents of synovial lining, cultured fibroblast-like synoviocytes (FLS) and macrophages.


METHODS
FLS and macrophages were cultured in the presence of inflammatory mediators. Real time polymerase chain reaction was used to quantify message levels in synovial biopsy specimens and cells. In situ hybridisation was employed to localise expression of cryopyrin mRNA.


RESULTS
Cryopyrin mRNA was raised in RA synovium and detected in both lining and sublining regions. FLS from RA and OA tissue expressed low baseline levels of cryopyrin transcripts that were induced by tumour necrosis factor alpha (TNFalpha). In contrast, macrophages differentiated in vitro expressed relatively high cryopyrin levels, which were further induced by TNFalpha, but not by interleukin 1beta. ASC mRNA levels were comparable in RA and OA tissue, FLS, and macrophages, and were depressed by TNFalpha in macrophages. Pyrin expression was higher in RA synovium than in OA tissue, and virtually undetectable in FLS but high in macrophages where it was unchanged by TNFalpha treatment.


CONCLUSIONS
These results suggest that enhanced cryopyrin levels in RA synovium are due to a greater numbers of tissue macrophages, and demonstrate transcriptional regulation of cryopyrin in a chronic inflammatory disease.
Rosengren
S
S
Division of Rheumatology, Allergy and Immunology, Department of Medicine, UCSD School of Medicine, 0656, 9500 Gilman Drive, La Jolla California 92093-0656, USA.
Hoffman
H M
HM
Bugbee
W
W
Boyle
D L
DL
D001172:Arthritis, Rheumatoid / Q000378:metabolism* / Q000473:pathology; D053468:CARD Signaling Adaptor Proteins; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D017403:In Situ Hybridization; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D015207:Osteoarthritis, Hip / Q000378:metabolism / Q000473:pathology; D020370:Osteoarthritis, Knee / Q000378:metabolism / Q000473:pathology; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D000071198:Pyrin; D012333:RNA, Messenger / Q000235:genetics; D013583:Synovial Membrane / Q000378:metabolism* / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D053468:CARD Signaling Adaptor Proteins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; C000604192:MEFV protein, human; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; C402202:PYCARD protein, human; D011506:Proteins; D000071198:Pyrin; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha