Importance of NF-kappaB in rheumatoid synovial tissues: in situ NF-kappaB expression and in vitro study using cultured synovial cells.
OBJECTIVE
To examine whether inhibition of NF-kappaB induces apoptosis of human synovial cells stimulated by tumour necrosis factor alpha (TNFalpha), interleukin 1beta (IL1beta), and anti-Fas monoclonal antibody (mAb).


METHODS
The expression of proliferating cell nuclear antigen (PCNA), NF-kappaB, and the presence of apoptotic synovial cells were determined in synovial tissues. Apoptosis of cultured synovial cells was induced by inhibition of NF-kappaB nuclear translocation by Z-Leu-Leu-Leu-aldehyde (LLL-CHO). The activation of caspase-3 and expression of XIAP and cIAP2 in synovial cells in LLL-CHO induced apoptosis was also examined.


RESULTS
Abundant PCNA+ synovial cells were found in rheumatoid arthritis (RA) synovial tissue, though a few apoptotic synovial cells were also detected in the RA synovial tissues. Nuclear NF-kappaB was expressed in RA synovial cells. Electrophoretic mobility shift assay showed that treatment of cells with TNFalpha or IL1beta significantly stimulated nuclear NF-kappaB activity. A small number of apoptotic synovial cells expressing intracellular active caspase-3 were found after treatment of cells with LLL-CHO. Although treatment of RA synovial cells with TNFalpha or IL1beta alone did not induce apoptosis, apoptosis induced by LLL-CHO and caspase-3 activation were clearly enhanced in TNFalpha or IL1beta stimulated synovial cells compared with unstimulated synovial cells. Furthermore, induction of apoptosis of synovial cells with caspase-3 activation by anti-Fas mAb was clearly increased by LLL-CHO. The expression of cIAP2 and XIAP in synovial cells may not directly influence the sensitivity of synovial cells to apoptosis induced by LLL-CHO.


CONCLUSIONS
The results suggest that NF-kappaB inhibition may be a potentially important therapeutic approach for RA by correcting the imbalance between apoptosis and proliferation of synovial cells in RA synovial tissue.
Yamasaki
S
S
The First Department of Internal Medicine, Nagasaki University School of Medicine, 1-7-1 Sakamoto, Nagasaki, Japan.
Kawakami
A
A
Nakashima
T
T
Nakamura
H
H
Kamachi
M
M
Honda
S
S
Hirai
Y
Y
Hida
A
A
Ida
H
H
Migita
K
K
Kawabe
Y
Y
Koji
T
T
Furuichi
I
I
Aoyagi
T
T
Eguchi
K
K
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D001172:Arthritis, Rheumatoid / Q000378:metabolism / Q000473:pathology*; D002243:Carbolines; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D051034:Inhibitor of Apoptosis Proteins; D007375:Interleukin-1 / Q000494:pharmacology; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D009842:Oligopeptides / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism*; D011506:Proteins / Q000032:analysis; D013268:Stimulation, Chemical; D013583:Synovial Membrane / Q000378:metabolism / Q000473:pathology*; D000068581:Tadalafil; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014764:Viral Proteins / Q000032:analysis; D051636:X-Linked Inhibitor of Apoptosis Protein; D019014:fas Receptor / Q000276:immunology
D000911:Antibodies, Monoclonal; D002243:Carbolines; D051034:Inhibitor of Apoptosis Proteins; D007375:Interleukin-1; D016328:NF-kappa B; D009842:Oligopeptides; D010726:Phosphodiesterase Inhibitors; D018809:Proliferating Cell Nuclear Antigen; D011506:Proteins; D014409:Tumor Necrosis Factor-alpha; D014764:Viral Proteins; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D019014:fas Receptor; C086430:inhibitor of apoptosis, Nucleopolyhedrovirus; D000068581:Tadalafil; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; C036671:leucyl-leucyl-leucine