Interstitial lung abnormalities in patients with early rheumatoid arthritis: A pilot study evaluating prevalence and progression.

OBJECTIVE:Pulmonary disease is a leading cause of morbidity and mortality in rheumatoid arthritis (RA). In this study, we investigated the prevalence and progression of interstitial lung abnormalities (ILA) in a prospective cohort study of 18 subjects with early RA. METHODS:Eighteen adults diagnosed with anti-citrullinated protein-antibody-positive RA within the prior year underwent baseline high-resolution computed tomography (HRCT), symptom assessment, and pulmonary function and laboratory testing. The follow-up HRCT and clinical assessment were completed after 1 year. RESULTS:Seven of the 18 patients (39%) had baseline HRCT abnormalities including septal thickening, honeycombing, ground glass opacities, and/or traction bronchiectasis. At follow-up, 6 out of the 7 subjects (86%) with ILAs at baseline exhibited progression, while 10 out of 11 (91%) without ILAs at baseline remained stable. A higher Clinical Chronic Obstructive Pulmonary Disease Questionnaire score was associated with both the presence and progression of HRCT abnormalities (10 vs 2, p=0.045; 10 vs 2, p=0.009, respectively). C-reactive protein (CRP) trended higher in patients with radiologic abnormalities (3.5 mg/L vs 1.1 mg/L, p=0.08) and was significantly higher in those with progression (3.5 mg/L vs 1 mg/L, p=0.024). Smoking, pulmonary function, and autoantibodies were not associated with HRCT abnormalities. CONCLUSION:ILAs are prevalent in patients with early RA. If identified at baseline, radiographic progression of ILAs after 1 year is likely, while those without ILAs at baseline are unlikely to develop new ILAs. In addition, early respiratory symptoms and higher CRP levels may correlate with the presence and progression of underlying ILAs

Heightened Levels of Antimicrobial Response Factors in Patients With Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic progressive autoimmune disease leading to considerable disability over time. The disease can be characterized by the presence of multiple autoantibodies in the serum and synovial fluid. Microbial dysbiosis is proposed to play a role in the pathogenesis of RA. Increased systemic bacterial exposure leads to elevated levels of antimicrobial response factors (ARFs) in the circulation. In the present study, we tested whether RA patients have increased levels of ARFs by analyzing the levels of multiple ARFs in serum from RA patients and healthy age and sex-matched controls. The levels of soluble CD14 (sCD14), lysozyme, and CXCL16 were significantly elevated in RA patients compared to healthy controls. Lipopolysaccharide binding protein (LBP) levels remained unchanged in RA patients compared to healthy controls. A positive correlation of LBP with rheumatoid factor (RF) was also found in RA subjects. Interestingly, the levels of anti-endotoxin core antibodies (EndoCAb) IgM, total IgM, EndoCAb IgA, and total IgA were significantly elevated in RA patients compared to healthy controls. No significant changes in the levels of EndoCAb IgG and total IgG were observed in RA patients compared to healthy controls. Furthermore, lysozyme and CXCL16 levels were positively correlated with disease severity among RA subjects. Increases in the levels of several ARFs and their correlations with clinical indices suggest systemic microbial exposure in the RA cohort. Modulation of microbial exposure may play an important role in disease pathogenesis in individuals with RA

Duration of Rheumatoid Arthritis and the Risk of Developing Interstitial Lung Disease

Age of ILD onset is similar in patients with RA-UIP and RA-NSIP but duration of RA before ILD onset differs

Interstitial lung abnormalities in patients with early rheumatoid arthritis: A pilot study evaluating prevalence and progression.

OBJECTIVE:Pulmonary disease is a leading cause of morbidity and mortality in rheumatoid arthritis (RA). In this study, we investigated the prevalence and progression of interstitial lung abnormalities (ILA) in a prospective cohort study of 18 subjects with early RA. METHODS:Eighteen adults diagnosed with anti-citrullinated protein-antibody-positive RA within the prior year underwent baseline high-resolution computed tomography (HRCT), symptom assessment, and pulmonary function and laboratory testing. The follow-up HRCT and clinical assessment were completed after 1 year. RESULTS:Seven of the 18 patients (39%) had baseline HRCT abnormalities including septal thickening, honeycombing, ground glass opacities, and/or traction bronchiectasis. At follow-up, 6 out of the 7 subjects (86%) with ILAs at baseline exhibited progression, while 10 out of 11 (91%) without ILAs at baseline remained stable. A higher Clinical Chronic Obstructive Pulmonary Disease Questionnaire score was associated with both the presence and progression of HRCT abnormalities (10 vs 2, p=0.045; 10 vs 2, p=0.009, respectively). C-reactive protein (CRP) trended higher in patients with radiologic abnormalities (3.5 mg/L vs 1.1 mg/L, p=0.08) and was significantly higher in those with progression (3.5 mg/L vs 1 mg/L, p=0.024). Smoking, pulmonary function, and autoantibodies were not associated with HRCT abnormalities. CONCLUSION:ILAs are prevalent in patients with early RA. If identified at baseline, radiographic progression of ILAs after 1 year is likely, while those without ILAs at baseline are unlikely to develop new ILAs. In addition, early respiratory symptoms and higher CRP levels may correlate with the presence and progression of underlying ILAs

Identification and Characterization of the Lactating Mouse Mammary Gland Citrullinome

Citrullination is a post-translational modification (PTM) in which positively charged peptidyl-arginine is converted into neutral peptidyl-citrulline by peptidylarginine deiminase (PAD or PADI) enzymes. The full protein citrullinome in many tissues is unknown. Herein, we used mass spectrometry and identified 107 citrullinated proteins in the lactation day 9 (L9) mouse mammary gland including histone H2A, alpha-tubulin, and beta-casein. Given the importance of prolactin to lactation, we next tested if it stimulates PAD-catalyzed citrullination using mouse mammary epithelial CID-9 cells. Stimulation of CID-9 cells with 5 microg/mL prolactin for 10 min induced a 2-fold increase in histone H2A citrullination and a 4.5-fold increase in alpha-tubulin citrullination. We next investigated if prolactin-induced citrullination regulates the expression of lactation genes beta-casein (Csn2) and butyrophilin (Btn1a1). Prolactin treatment for 12 h increased beta-casein and butyrophilin mRNA expression; however, this increase was significantly inhibited by the pan-PAD inhibitor, BB-Cl-amidine (BB-ClA). We also examined the effect of tubulin citrullination on the overall polymerization rate of microtubules. Our results show that citrullinated tubulin had a higher maximum overall polymerization rate. Our work suggests that protein citrullination is an important PTM that regulates gene expression and microtubule dynamics in mammary epithelial cells

Anti-peptidylarginine deiminase-4 antibodies at mucosal sites can activate peptidylarginine deiminase-4 enzyme activity in rheumatoid arthritis

Abstract Background Mucosal sites are hypothesized to play a role in the development of rheumatoid arthritis (RA). Since serum anti-peptidylarginine deiminase (PAD)4 antibodies, including a subset that cross-react with PAD3 (PAD3/4), are specific for RA and associate with severe disease, we sought to examine whether anti-PAD4 and anti-PAD3/4 antibodies were present in the lung and oral mucosa of subjects with RA and “at-risk” for RA. Methods We included 37 RA, 25 healthy control, and 46 subjects “at-risk” for RA based on familial RA and/or serum anti-citrullinated protein antibody (ACPA) positivity. Paired serum, sputum, and saliva were evaluated for anti-PAD4 and anti-PAD3/4 using immunoprecipitation and ACPA using ELISA. Immunoglobulins (Ig) were purified from representative samples, and their effect on citrullination of histone H3 by recombinant human PAD4 was measured by anti-citH3 immunoblot. Results Anti-PAD4 antibodies were detected in the serum of 6/37 (16.2%), sputum of 3/37 (8.1%), and saliva of 3/33 (9.1%) RA subjects and in the serum and sputum of 1/46 (2.2%) at-risk subjects. None of the healthy controls had anti-PAD4 antibodies at any site. Serum, sputum, and salivary anti-PAD4 antibodies were more prevalent in RA subjects with RA duration >2 years. Purified antibodies from representative anti-PAD4-positive and anti-PAD3/4-positive sputum were primarily of the IgA isotype and able to increase PAD4 enzymatic activity. Conclusions Anti-PAD4 antibodies are present in the sputum and saliva of a portion of RA patients and are infrequent in at-risk subjects. Importantly, the ability of anti-PAD4, and particularly anti-PAD3/4, antibodies in the sputum to enhance PAD4 enzymatic activity suggests that anti-PAD4 may play an active role in the RA lung

Association of Antibodies to Citrullinated Protein Antigens with Blood Pressure in First-Degree Relatives of Rheumatoid Arthritis Patients: The Studies of the Etiology of Rheumatoid Arthritis

BackgroundHypertension is more common in patients with rheumatoid arthritis (RA) than in the general population. It is unknown whether hypertension is due to RA-related medications or the disease itself. Therefore, we sought to investigate associations between RA-related autoantibodies, specifically antibodies to citrullinated protein antigens (ACPA) and systolic blood pressure (SBP) and diastolic blood pressure (DBP) in first-degree relatives of RA patients, who were free of RA and RA-related medications. We hypothesized that a greater number of detectable ACPA would be associated with high SBP and DBP, independent of other risk factors in these first-degree relatives.MethodsWe evaluated associations between ACPA and SBP and DBP in a cross-sectional study of 72 first-degree relatives (defined as parent, child, or sibling) of RA patients. Fifteen ACPA were measured using a Bio-Plex bead-based assay; each was dichotomized as positive/negative based on pre-specified cut-points. Analysis of covariance was used to evaluate associations between ACPA positivity and SBP and DBP, adjusting for age, sex, race, body mass index (BMI), pack-years of smoking, high sensitivity C-reactive protein (hsCRP), and current use of anti-hypertensive medications.ResultsAverage age was 51 and 69% were women. Mean SBP was 119 ± 18 and DBP was 74 ± 9 mm Hg. Thirty-three (46%) first-degree relatives were positive for ≥1 ACPA; and were younger, had lower BMI, more pack-years of smoking, and higher hsCRP concentrations compared to ACPA negative first-degree relatives. For each additional positive ACPA, SBP was 0.98 ± 0.5 mm Hg (p = 0.05) higher, and DBP was 0.66 ± 0.3 mm Hg (p = 0.04) higher. Anti-cit-fibrinogen A (211-230) positive and anti-cit-filaggrin positive first-degree relatives had 11.5 and 13.9 mm Hg higher SBP (p = 0.02) respectively. Anti-cit-clusterin, cit-filaggrin, and cit-vimentin positive first-degree relatives had 7-8 mm Hg higher DBP (p = 0.03, 0.05, 0.05 respectively), compared to being negative for these individual ACPA. Consistent with associations between ACPA, SBP, and DBP, anti-cyclic citrullinated peptides (anti-CCP2) positive first-degree relatives had 16.4± (p = 0.03) higher SBP and 12.1± mm Hg (p = 0.01) higher DBP than anti-CCP2 negative first-degree relatives.ConclusionIn first-degree relatives without RA, ACPA positivity is associated with higher SBP and DBP. Subclinical autoimmune processes and ACPA may play a role in the vascular changes potentially leading to hypertension prior to RA onset

Malondialdehyde-Acetaldehyde Adducts and Antibody Responses in Rheumatoid Arthritis-Associated Interstitial Lung Disease

To compare serum anti-malondialdehyde-acetaldehyde (anti-MAA) antibody levels and MAA expression in lung tissue from patients with rheumatoid arthritis-associated interstitial lung disease (RA-ILD) to those found in controls. Anti-MAA antibody (IgA, IgM, IgG) concentrations were measured in patients with RA-ILD and compared to those of RA patients with chronic obstructive pulmonary disease (COPD) and RA patients without lung disease. Associations between anti-MAA antibody with RA-ILD were assessed using multivariable logistic regression. Lung tissue from patients with RA-ILD, other ILD, or emphysema, and from controls (n = 3 per group) were stained for MAA, citrulline, macrophages (CD68), T cells (CD3), B cells (CD19/CD27), and extracellular matrix proteins (type II collagen, fibronectin, vimentin). Tissue expression and colocalization with MAA were quantified and compared. Among 1,823 RA patients, 90 had prevalent RA-ILD. Serum IgA and IgM anti-MAA antibody concentrations were higher in RA-ILD than in RA with COPD or RA alone (P = 0.005). After adjustment for covariates, the highest quartiles of IgA anti-MAA antibody concentration (odds ratio 2.09 [95% confidence interval 1.11-3.90]) and IgM (odds ratio 2.23 [95% confidence interval 1.19-4.15]) were significantly associated with the presence of RA-ILD. MAA expression in RA-ILD lung tissue was greater than in tissue from all other groups (P < 0.001), and it colocalized with citrulline (r = 0.79), CD19+ B cells (r = 0.78), and extracellular matrix proteins (type II collagen [r = 0.72] and vimentin [r = 0.77]) to the greatest degree in RA-ILD. Serum IgA and IgM anti-MAA antibody is associated with ILD among RA patients. MAA is highly expressed in RA-ILD lung tissue, where it colocalizes with other RA autoantigens, autoreactive B cells, and extracellular matrix proteins, highlighting its potential role in the pathogenesis of RA-ILD