Clinical significance of anti-filaggrin antibody recognizing uncitrullinated filaggrin in rheumatoid arthritis.
Filaggrin is expressed in the cornified layer of epidermis and known to be one of the antigenic targets in rheumatoid arthritis. Although the citrulline residue in filaggrin is thought to be an antigenic determinant recognized by autoantibodies, the diagnostic sensitivity of synthetic citrullinated peptide is variable. To investigate the implication of anti-filaggrin antibodies recognizing uncitrullinated filaggrin in rheumatoid arthritis, we assayed antibody titers using unmodified recombinant filaggrin in the sera from 73 patients with rheumatoid arthritis, 150 patients with other connective tissue diseases and 70 normal controls. We also performed the correlation analysis between antibody titers and the clinical variables in patients with rheumatoid arthritis. Titers of IgG anti-filaggrin antibodies were significantly higher in rheumatoid arthritis patients compared to normal controls (P=0.02), but not in patients with osteoarthritis, ankylosing spondylitis or systemic lupus erythematosus. IgG anti-filaggrin antibodies were more frequently found in patients with rheumatoid arthritis compared to normal controls (12.3% vs 1.4% respectively, P=0.04). An anti-filaggrin antibody titer was correlated with visual analogue scale of pain, tender joint count, Ritchie articular index or C-reactive protein, but not with anti-nuclear antibody or rheumatoid factor. These results suggest that anti-filaggrin antibody recognizes the uncitrullinated filaggrin as an antigen and its titer correlates with clinical parameters, explaining the variable sensitivity of anti-filaggrin antibody test.
Choi
Kyung Ho
KH
Department of Biochemistry and Molecular Biology, Biology/Aging and Apoptosis Research Center, Seoul National University College of Medicine, Seoul 110-799, Korea.
Lee
Eun Bong
EB
Yoo
Chang Dal
CD
Baek
Han Joo
HJ
Kang
Seong Wook
SW
Shin
Ki Chul
KC
Lee
Yun Jong
YJ
Kim
Hyun Ah
HA
Jeon
Ju Hong
JH
Kim
Chai Wan
CW
Shin
Dong Myung
DM
Kim
In Gyu
IG
Son
Yeong Wook
YW
D000595:Amino Acid Sequence; D000906:Antibodies / Q000097:blood* / Q000276:immunology*; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000175:diagnosis* / Q000276:immunology*; D016022:Case-Control Studies; D002956:Citrulline / Q000032:analysis*; D000091344:Filaggrin Proteins; D006801:Humans; D007381:Intermediate Filament Proteins / Q000737:chemistry* / Q000276:immunology* / Q000302:isolation & purification; D008969:Molecular Sequence Data
D000906:Antibodies; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D002956:Citrulline