Fibroblast-like synoviocytes from patients with rheumatoid arthritis are more sensitive to apoptosis induced by the viral protein, apoptin, than fibroblast-like synoviocytes from trauma patients.
OBJECTIVE
Fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis (RA) show characteristics of transformation. Because the chicken anemia virus protein, apoptin, induces apoptosis solely in transformed cells, it was investigated whether FLS from patients were more sensitive to apoptin-induced apoptosis than FLS from normal joints obtained from trauma patients.


METHODS
FLS were transduced with maltose-binding protein (MBP)-apoptin recombinant protein or MBP as a control protein by microinjection. After 24 hours, cells were fixed and stained with immunofluorescence to detect apoptin or MBP and the number of dead cells was assessed. Furthermore, phosphorylation of apoptin was analysed in FLS from patients with RA and from trauma patients by in vitro kinase assay.


RESULTS
FLS from patients with RA were significantly more sensitive to apoptin-induced apoptosis than FLS from trauma patients (p = 0.0263). Furthermore, MBP-apoptin induced more apoptosis than MBP in RA FLS (p = 0.004). No phosphorylation of apoptin was observed in FLS from patients with RA.


CONCLUSIONS
FLS from patients with RA are more sensitive to apoptin-induced apoptosis than normal FLS, which is consistent with a transformed phenotype of these cells. However, given the lack of phosphorylation of apoptin in RA FLS the mechanism of action of apoptin seems to differ between tumour cells and RA FLS. This study indicates that apoptin may help to identify a new therapeutic pathway against hyperplasia of the synovium and joint destruction in RA.
Tolboom
T C A
TC
Department of Rheumatology, Leiden University Medical Center, The Netherlands.
Zhang
Y-H
YH
Henriquez
N V
NV
Nelissen
R G H H
RG
Toes
R E M
RE
Noteborn
M H M
MH
Huizinga
T W J
TW
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis / Q000187:drug effects*; D001172:Arthritis, Rheumatoid / Q000473:pathology*; D036022:Capsid Proteins / Q000494:pharmacology*; D002352:Carrier Proteins / Q000235:genetics / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D017727:Chicken anemia virus; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000473:pathology*; D005822:Genetic Vectors / Q000494:pharmacology; D006801:Humans; D008297:Male; D058619:Maltose-Binding Proteins; D008845:Microinjections; D008875:Middle Aged; D011994:Recombinant Proteins; D013583:Synovial Membrane / Q000187:drug effects / Q000473:pathology*; D014161:Transduction, Genetic; D014947:Wounds and Injuries / Q000473:pathology*
D036022:Capsid Proteins; D002352:Carrier Proteins; D058619:Maltose-Binding Proteins; D011994:Recombinant Proteins; C091717:VP3 protein, Chicken anemia virus