Chronic lung diseases including interstitial lung disease and airway disease (AD) occur in RA patients. Interstitial lung disease and AD in RA are extra-articular manifestations that influence the prognosis quoad vitam of RA. Studies on associations of HLA alleles with RA have been carried out, and shared epitopes of several alleles are reported to be associated with RA susceptibility. Few association studies in RA subpopulations with chronic lung diseases have been conducted. The aim of the study was to identify HLA alleles predisposing to RA phenotypes including the presence of AD.
Associations of HLA-DRB1 and DQB1 alleles with chronic lung diseases in RA were analysed.
A positive association was found between the DR4 serological group and resistance to usual interstitial pneumonia [P = 0.0250, odds ratio (OR) 0.62, 95% CI: 0.41, 0.93]. The DR2 serological group was associated with susceptibility to usual interstitial pneumonia (P = 0.0036, OR = 1.86, 95% CI: 1.23, 2.81). An association was found for shared epitopes alleles with bronchiolitic AD (P = 0.0040, OR = 2.06, 95% CI: 1.24, 3.41). DQB1*03:01 was associated with bronchiectatic AD (P = 0.0021, corrected P-value (Pc) = 0.0315, OR = 1.99, 95% CI: 1.30, 3.06), as well as with emphysema (P = 0.0007, Pc = 0.0104, OR = 2.43, 95% CI: 1.49, 3.95). In combined analysis, a predisposing association of DQB1*03:01 (P = 1.94 ×10(-5), Pc = 0.0003, OR = 2.16, 95% CI: 1.53, 3.06) and a negative association of DQB1*03:02 (P = 0.0008, Pc = 0.0117, OR = 0.33, 95% CI: 0.17, 0.67) with bronchiectatic AD or emphysema were observed in RA.
The present study identified an association of HLA-DQB1*03:01 with predisposition to, and DQB1*03:02 with resistance to, bronchiectatic AD or emphysema in RA.