Anti-hnRNP and other autoantibodies in systemic sclerosis with joint involvement.
OBJECTIVE
To investigate joint involvement in SSc and its relationship with autoantibody to the hnRNP and to anti-cyclic citrullinated peptide (anti-CCP).


METHODS
Sera from 55 SSc patients were investigated. Joint involvement was determined by clinical, radiological and ultrasonographical evaluation. Anti-hnRNP proteins A1 and A2 (anti-hnRNP-A1/A2) antibodies were determined by immunoblotting. Anti-CCP, ACA, anti-topo I (ATA), Sm, U1-RNP, ribosomal RNP, Ro/SSA, La/SSB autoantibody and RF were determined.


RESULTS
Six patients were positive for anti-hnRNP-A2 autoantibody and two were anti-A1 positive. Eight patients had joint erosions: seven of the eight patients positive for anti-hnRNP-A2 or A1 presented articular involvement (P < 0.04) and five of the eight erosive patients were positive for either of the two autoantibodies (P < 0.02). Of the four patients positive for anti-CCP, none had anti-hnRNP but three had erosive aspects. ATAs were found in 10 patients, six of which were also positive for anti-hnRNP (P < 0.05). RF was positive in 16 patients and in seven among those with articular involvement (P < 0.04). RF was significantly associated with anti-hnRNP in patients with erosive arthritis (P < 0.02), but not with the presence of anti-hnRNP alone. Epitope mapping of the three strongest anti-hnRNP-A2-positive sera recognized the same major epitope as patients with RA. SSc patients have higher incidence of erosions and anti-hnRNP-A2/A1 positivity. RF test and anti-hnRNP had a statistically significant diagnostic value for articular involvement.


CONCLUSIONS
These parameters might suggest that autoantibody to both hnRNP antigens might become a non-specific but useful marker for joint involvement in SSc patients and identify SSc patients prone to develop joint damage.
Generini
Sergio
S
Department of Biomedicine, Division of Rheumatology AOUC, Denothe Center, University of Florence, Florence, Italy.
Steiner
Günter
G
Miniati
Irene
I
Conforti
Maria L
ML
Guiducci
Serena
S
Skriner
Karl
K
Kaloudi
Olga
O
Giacomelli
Roberto
R
Smolen
Josef
J
Matucci-Cerinic
Marco
M
D000328:Adult; D000368:Aged; D001175:Arthrography; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D005260:Female; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000276:immunology; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000276:immunology*; D006801:Humans; D007596:Joints / Q000276:immunology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology; D011336:Probability; D012595:Scleroderma, Systemic / Q000000981:diagnostic imaging / Q000276:immunology*; D014463:Ultrasonography
D001323:Autoantibodies; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; C439768:hnRNP A2