Associations between genetic factors, tobacco smoking and autoantibodies in familial and sporadic rheumatoid arthritis.
OBJECTIVE
The objective of this study was to investigate the association between genes (HLA-DRB1 and PTPN22) and tobacco smoking, separately as well as combined, and serological markers of rheumatoid arthritis (RA) in a French population with RA.


METHODS
274 patients with RA with half of them belonging to RA multicase families, were genotyped for HLA-DRB1 allele and for PTPN22-1858 polymorphism. IgM rheumatoid factor and anti-cyclic citrullinated peptide (anti-CCP) antibodies were determined by ELISA method. The search for association relied on chi(2) test and odds ratio with 95% confidence interval calculation. The interaction study relied on the departure-from-additivity-based method.


RESULTS
The presence of at least one shared epitope (SE) allele was associated with anti-CCP antibodies presence (82.5% vs. 68.4%, p = 0.02), particularly with HLA-DRB1*0401 allele (28.0% vs. 16.4%, p = 0.01). Tobacco exposure was associated with anti-CCP antibodies, but only in presence of SE. A tendency toward an interaction was found between tobacco, the presence of at least one HLA-DRB1*0401 allele and anti-CCP antibodies (attributable proportion due to interaction = +0.24 (-0.21+0.76)). The cumulative dose of cigarette smoking was correlated with anti-CCP antibody titres (r = 0.19, p = 0.04). The presence of both SE and 1858T alleles was associated with a higher, but not significantly different, risk for anti-CCP antibodies presence than for each separately. No association was found between PTPN22-1858T allele and tobacco smoking for autoantibody positivity.


CONCLUSIONS
Our findings suggest an association between SE alleles and tobacco smoking for anti-CCP positivity and a tendency toward an interaction between the HLA-DRB1*0401 allele and smoking for anti-CCP positivity in this sample of RA.
GenHotel-EA 3886, Laboratoire de Recherche Européen pour la Polyarthrite Rhumatoïde, ECRAF-Université Paris 7-Université d'Evry, 2 rue Gaston Crémieux, CP 5727, 91057 Evry-Genopole cedex, France. michou@polyarthrite.net
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L
Michou
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VH
Teixeira
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C
Pierlot
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S
Lasbleiz
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Bardin
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Dieudé
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Prum
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Cornélis
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Petit-Teixeira
D000328:Adult; D000483:Alleles; D001172:Arthritis, Rheumatoid / Q000209:etiology / Q000235:genetics* / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006684:HLA-DR Antigens / Q000235:genetics; D059811:HLA-DRB1 Chains; D006801:Humans; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22 / Q000235:genetics; D012217:Rheumatoid Factor / Q000097:blood; D012907:Smoking / Q000009:adverse effects* / Q000235:genetics
D001323:Autoantibodies; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; C553505:HLA-DRB1*04:01 antigen; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D012217:Rheumatoid Factor; C516765:PTPN22 protein, human; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22