Serum rheumatoid factor IgA, anti-citrullinated peptide antibodies with secretory components, and anti-carbamylated protein antibodies associate with interstitial lung disease in rheumatoid arthritis.

Rheumatoid arthritis (RA) is often complicated with chronic lung diseases (CLD), including interstitial lung disease (ILD) and airway disease, which occur as extra-articular manifestations. CLD in RA have been associated with the production of rheumatoid factor (RF), anti-citrullinated peptide antibody (ACPA), or anti-carbamylated protein (CarP) antibody. However, few validation studies have been performed thus far. In the present study, we investigated the association of RF, ACPA, and anti-CarP antibodies with RA complicated with CLD. Sera from RA patients with or without CLD were collected. The levels of serum RF, RF immunoglobulin A (IgA), ACPA IgG, ACPA IgA, and ACPA secretory component (SC) were measured using enzyme-linked immunosorbent assay. The comparison of RA patients with and without CLD showed that RF IgA was associated with ILD (mean ± standard deviation: 206.6 ± 400.5 vs. 95.0 ± 523.1 U/ml, respectively, P = 1.13 × 10- 8), particularly usual interstitial pneumonia (UIP) (263.5 ± 502.0 U/ml, P = 1.00 × 10- 7). ACPA SC was associated with RA complicated with ILD (mean ± standard deviation: 8.6 ± 25.1 vs. 2.3 ± 3.4 U/ml, respectively, P = 0.0003), particularly nonspecific interstitial pneumonia (NSIP) (10.7 ± 31.5 U/ml, P = 0.0017). Anti-CarP antibodies were associated with RA complicated with ILD (0.042 ± 0.285 vs. 0.003 ± 0.011 U/ml, respectively, P = 1.04X10- 11). RF IgA and ACPA SC in RA were associated with UIP and NSIP, respectively, suggesting different specificities in patients with RA. Anti-CarP antibodies were associated with ILD in RA. These results may help elucidate the different pathogeneses of UIP and NSIP in RA.

Oka S ，Higuchi T ，Furukawa H ，Shimada K ，Okamoto A ，Hashimoto A ，Komiya A ，Saisho K ，Yoshikawa N ，Katayama M ，Matsui T ，Fukui N ，Migita K ，Tohma S ... -  《BMC MUSCULOSKELETAL DISORDERS》

Presence of autoantibodies in "seronegative" rheumatoid arthritis associates with classical risk factors and high disease activity.

Reed E ，Hedström AK ，Hansson M ，Mathsson-Alm L ，Brynedal B ，Saevarsdottir S ，Cornillet M ，Jakobsson PJ ，Holmdahl R ，Skriner K ，Serre G ，Alfredsson L ，Rönnelid J ，Lundberg K ... -  《-》

Serum anti-citrullinated protein antibodies and rheumatoid factor increase the risk of rheumatoid arthritis-related interstitial lung disease: a meta-analysis.

This meta-analysis aims to determine the association between antibodies including anti-citrullinated protein antibodies (ACPA) and rheumatoid factors (RF) and risk of rheumatoid arthritis-related interstitial lung disease (RA-ILD). PubMed, Embase, and Cochrane were searched up to September 13, 2020, for studies investigating the risk of RA-ILD in ACPA-positive patients. The statistical meta-analysis and sensitivity analysis were performed using the Review Manager 5.4 and Stata16.0 software, respectively. Total 1 double-blind randomized controlled study and 16 observational studies, including 992 RA-ILD patients and 2223 RA-non ILD patients, met the inclusion criteria of the meta-analysis. Compared with ACPA-negative patients, positive serum ACPA increased the risk of RA-ILD (OR = 2.51; 95% CI: 1.35-4.68; P = 0.004) and serum ACPA titer was significantly correlated with risk of RA-ILD (SMD = 0.39; 95% CI: 0.17-0.62; P = 0.0006). In a region-based subgroup analysis, ACPA titer in Asian, European, and African populations was significantly related to the risk of RA-ILD, while there was no significant correlation in the Americans (SMD =  - 0.03; 95% CI: - 0.89-0.83; P = 0.95), especially in the USA (SMD = 0.37; 95% CI: - 0.26-0.99; P = 0.25). In addition, serum positive RF increased the risk of RA-ILD (OR = 2.85; 95% CI: 2.19-3.71; P < 0.00001) and serum RF titer was significantly correlated with the risk of RA-ILD (SMD = 0.35; 95% CI: 0.23-0.46; P < 0.00001). However, for the analysis of RF dichotomous data, the funnel shape was asymmetric and the p value of egger test was less than 0.05, which indicated potential publication bias. ACPA and RF positive patients have greater risk of RA-ILD, and RA patients positive for ACPA should be paid more attention. • Autoantibodies ACPA and RF increase the risk of RA-ILD. • Regions may be related to RA-ILD.

Xie S ，Li S ，Chen B ，Zhu Q ，Xu L ，Li F ... -  《-》

Distinctive Clinical Characteristics and Outcome of ILD-Onset Rheumatoid Arthritis and ACPA-Positive ILD: a Longitudinal Cohort of 282 Cases.

Chen RX ，Zhao LD ，Xiao XY ，Song L ，Du HY ，Xu ZJ ，Feng RE ，Yang HX ，Fei YY ，Zhang W ，Zhang FC ，Chen H ，Zhang X ... -  《-》

Determination of Autoantibody Isotypes Increases the Sensitivity of Serodiagnostics in Rheumatoid Arthritis.

Sieghart D ，Platzer A ，Studenic P ，Alasti F ，Grundhuber M ，Swiniarski S ，Horn T ，Haslacher H ，Blüml S ，Smolen J ，Steiner G ... -  《Frontiers in Immunology》