Association of fine specificity and repertoire expansion of anticitrullinated peptide antibodies with rheumatoid arthritis associated interstitial lung disease

A dose-dependent beneficial effect of methotrexate on the risk of interstitial lung disease in rheumatoid arthritis patients

Objectives

The aim of the study was to assess the influence of different factors, including treatment, on the risk of ILD in the course of RA.

Methods

A total of 109 RA patients were included in the analysis. High-resolution computed tomography (HRCT) of chest was obtained in each patient. Patients were classified as having ILD (ILD group) or not (N-ILD group). The ILD was graded using the semi-quantitative Warrick scale of fibrosis. Warrick extent score (WES) and Warrick severity score (WSS) were calculated separately for each patient, then combined to obtain a global score (WGS).

Results

In univariate analysis the presence of ILD was associated positively with age (P = 5x10^-6) and negatively with MTX treatment (P = 0.0013), mean MTX dose per year of treatment (P = 0.003) and number of DMARDs used (P = 0.046). On multivariate analysis only age and treatment with MTX were independently associated with the presence of ILD. WGS was significantly lower in patients treated with MTX in a dose of ≥15 mg/week (MTX≥15 group) as compared to patients treated with lower doses of MTX (0<MTX<15 group) or not treated with MTX (N-MTX group) (P = 0.04 and P = 0.037, respectively). The ILD prevalence was higher in N-MTX group than in 0<MTX<15 group (P = 0.0036) and MTX≥15 group (0.0007). The difference in ILD prevalence between MTX≥15 and 0<MTX<15 groups was not significant, but the latter group had higher WES (P = 0.044) and trended to have higher WSS and WGS.

Consclusions

We found a beneficial effect of MTX on RA-ILD. Importantly, this effect seems to be dose dependent.

Analysis of Clinical-Analytical Characteristics in Patients with Rheumatoid Arthritis and Interstitial Lung Disease: Case-Control Study

OBJECTIVES

To study the differences between rheumatoid arthritis (RA)-interstitial lung disease (ILD) patients and RA patients without ILD in severity markers and disease activity and to identify factors associated with the presence of ILD in RA patients.

PATIENTS AND METHODS

Patients: RA-ILD patients selected from a multicentre cohort in Andalusia, Spain.

CONTROLS

RA-patients without ILD paired by sex, age and disease duration.

PROTOCOL

RA patients are reviewed every 3-6months in rheumatology consultation. All patients are reviewed according to a predetermined protocol with systematic data collection.

OUTCOMES

description of ILD type, differences in severity markers and disease activity in both groups. Other variables: ILD type by imaging technique (HRCT): nonspecific interstitial pneumonia (NSIP)/usual interstitial pneumonia (UIP). Lung function by PTF. Activity and severity markers of arthritis by DAS28-ESR, HAQ, RF, ACPA and erosions. Treatment with DMARD.

STATISTICAL ANALYSIS

descriptive and paired T-test or Chi-square test followed by binary logistic regression (DV: ILD in patients with RA).

RESULTS

Eighty-two patients were included, 41 RA-ILD and 41 RA controls. RF and ACPA positivity, serositis and osteoporosis were more frequent in RA-ILD patients. No significant differences in DAS28 were observed (P=.145) between RA-ILD and RA control patients. RA-ILD patients presented worse HAQ scores (P=.006). All patients were treated with disease modifying antirheumatic drugs (DMARDs). The risk of developing ILD in RA patients is tripled by a history of smoking or the presence of erosive arthritis (R²=.36).

CONCLUSIONS

The results of our study support the higher frequency of UIP and NSIP in RA patients. DLCO is the most sensitive parameter to detect ILD in RA patients. Our study showed that ILD in RA patients was associated with RA severity (presence of erosions and ACPA) and with a history of smoking.

Systematic review and meta-analysis of the risk of rheumatoid arthritis-associated interstitial lung disease related to anti-cyclic citrullinated peptide (CCP) antibody

OBJECTIVE

To clarify the risk of rheumatoid arthritis-associated interstitial lung disease (RA-ILD) related to anti-cyclic citrullinated peptide (CCP) antibody.

ELIGIBILITY CRITERIA

Patients with RA with and without ILD were eligible. The primary outcome was the prevalence or incidence of ILD. Primary studies of any design aside from a case report were eligible.

INFORMATION SOURCES

Medline, EMBASE, Science Citation Index Expanded and Cochrane Central Register of Controlled Trials were searched from the inception through 12 November 2019.

DATA EXTRACTION AND RISK OF BIAS

Two reviewers independently selected eligible reports, extracted relevant data and assessed risk of bias using a modified Quality in Prognostic Studies tool.

DATA SYNTHESIS

Meta-analysis was conducted using a random-effects model.

QUALITY OF EVIDENCE

The Grades of Recommendation, Assessment, Development and Evaluation system was applied.

RESULTS

Among 29 out of 827 records retrieved through electronic databases and four additional reports identified from other sources, 29 studies were focused for the review. A total of 10158 subjects were included and the mean age at inclusion was between 45.8 and 63.9 years. The mean RA duration was between 4.3 and 14.9 years. The positivity of anti-CCP antibody ranged from 50.7% to 95.8%. All studies except for two were deemed as high risk of bias. A pooled analysis of univariate results demonstrated that the presence of anti-CCP antibody was significantly associated with RA-ILD with an OR of 2.10 (95% CI: 1.59 to 2.78). Similarly, the titre of anti-CCP antibody was significantly higher for RA-ILD with a standardised mean difference of 0.42 (95% CI: 0.20 to 0.65). These results were confirmed by multivariate analysis in the majority of studies and consistent by any subgroup and sensitivity analyses.

CONCLUSION

The presence and higher titres of anti-CCP antibody were suggested to be significantly associated with an increased risk of RA-ILD. However, the quality of evidence was rated as low or very low.

Beyond the joints, the extra-articular manifestations in rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory disease typically affecting the joints, but the systemic inflammatory process may involve other tissues and organs. Many extra-articular manifestations are recognized, which are related to worse long outcomes. Rheumatoid nodules are the most common extra-articular feature, found in about 30% of patients. Secondary Sjögren's syndrome and pulmonary manifestations are observed in almost 10% of patients, also in the early disease. Active RA with high disease activity has been associated with an increased risk of such features. Male gender, smoking habit, severe joint disease, worse function, high pro-inflammatory markers levels, high titer of rheumatoid factor, and HLA-related shared epitope have been reported as clinical predictors of occurrence of these rheumatoid complications. In addition, there is a little evidence deriving from randomized controlled trials in this field, thus the therapeutic strategy is mainly empiric and based on small case series and retrospective studies. However, considering that these extra-articular manifestations are usually related to the more active and severe RA, an aggressive therapeutic strategy is usually employed in view of the poor outcomes of these patients. The extra-articular features of RA remain, despite the improvement of joint damage, a major diagnostic and therapeutic challenge, since these are associated with a poor prognosis and need to be early recognized and promptly managed.

Lifestyle and Clinical Risk Factors for Incident Rheumatoid Arthritis-associated Interstitial Lung Disease

OBJECTIVE

To determine the association between novel lifestyle factors on risk of rheumatoid arthritis (RA)-associated interstitial lung disease (ILD), define the threshold at which smoking increases RA-ILD risk, and calculate the degree to which known lifestyle and clinical factors predict RA-ILD.

METHODS

This nested case-control study matched incident RA-ILD cases to RA non-ILD controls on age, sex, RA duration, rheumatoid factor, and time from exposure assessment to RA-ILD. Exposures included education, BMI, smoking, anticyclic citrullinated peptide antibodies, race, joint erosions, rheumatoid nodules, C-reactive protein (CRP), disease activity score, functional status, disease-modifying antirheumatic drug use, and glucocorticoid use. OR for each exposure on risk of RA-ILD were obtained from logistic regression models. Area under the curve (AUC) was calculated based on all lifestyle and clinical exposures.

RESULTS

We identified 84 incident RA-ILD cases and 233 matched controls. After adjustment, obesity, high-positive CRP (≥ 10 mg/L), and poor functional status (multidimensional Health Assessment Questionnaire [MDHAQ] ≥ 1) were associated with increased risk of RA-ILD (OR 2.42, 95% CI 1.11-5.24 vs normal BMI; OR 2.61, 95% CI 1.21-5.64 vs CRP < 3 mg/L; OR 3.10, 95% CI 1.32-7.26 vs MDHAQ < 0.2). Smoking 30 pack-years or more was strongly associated with risk of RA-ILD compared to never smokers (OR 6.06, 95% CI 2.72-13.5). Together, lifestyle and clinical risk factors for RA-ILD had an AUC of 0.79 (95% CI 0.73-0.85).

CONCLUSION

Obesity, CRP, functional status, and extensive smoking may be novel risk factors for RA-ILD that may be useful for RA-ILD risk assessment and prevention. The overall ability to predict RA-ILD remains modest.

Rheumatoid arthritis-associated interstitial lung disease: Current update on prevalence, risk factors, and pharmacologic treatment

Purpose of review

Rheumatoid arthritis-associated interstitial lung disease (RA-ILD) is one of the most serious extra-articular RA manifestations. RA-ILD is associated with worse physical function, lower quality of life, and increased mortality. RA-ILD is comprised of heterogeneous subtypes characterized by inflammation and fibrosis. Diagnosis can be difficult since the presentation of RA-ILD is characterized by non-specific symptoms and imaging findings. Management of RA-ILD is also challenging due to difficulty in precisely measuring pulmonary disease activity and response to treatment in patients who may also have articular inflammation. We provide a current overview of RA-ILD focusing on prevalence, risk factors, and treatment.

Recent findings

Research interest in RA-ILD has increased in recent years. Some studies suggest that RA-ILD prevalence may be increasing; this may be due to underlying biologic drivers or increases in imaging and recognition. Novel RA-ILD risk factors include the MUC5B promotor variant, articular disease activity, autoantibodies, and biomarkers of damaged pulmonary parenchyma. Treatment should focus on controlling RA disease activity, which emerging data suggest may reduce RA-ILD risk. Immunomodulatory and antifibrotic drugs may also treat RA-ILD.

Summary

RA-ILD is an underrecognized and serious manifestation of RA, but important progress is being made in identifying risk factors and treatment.

Secretory anti-citrullinated protein antibodies in serum associate with lung involvement in early rheumatoid arthritis

Objective

A ‘mucosal connection’ in RA presently attracts increasing attention. We recently described the occurrence of secretory antibodies to citrullinated protein (SC-ACPA) in sera from patients with recent-onset RA. The current study was performed to evaluate possible associations between serum levels of secretory ACPA and signs of lung involvement in patients with early, untreated RA.

Methods

One hundred and forty-two RA patients were included as part of the ‘LUng Investigation in newly diagnosed RA’ study. One hundred and six patients were examined with high-resolution CT (HRCT) and 20 patients underwent bronchoscopy, where bronchial biopsies and bronchoalveolar lavage fluid (BALF) samples were obtained. SC-ACPA in serum and BALF were detected by an enzyme-linked immunoassay. Antibody levels were related to smoking history, pulmonary function, HRCT, BALF cell counts and findings in bronchial biopsies.

Results

SC-ACPA occurred in 16% of the serum samples and in 35% of the BALF samples. SC-ACPA levels in serum correlated with SC-ACPA levels in BALF (σ = 0.50, P = 0.027) and were higher among patients with HRCT parenchymal lung abnormalities (P = 0.022) or bronchiectasis (P = 0.042). Also, ever smoking was more frequent among serum SC-ACPA-positive patients (91% vs 67%, P = 0.023), and the SC-ACPA levels correlated with the number of pack-years (σ=0.20, P = 0.020).

Conclusion

In early, untreated RA, serum levels of SC-ACPA reflect lung involvement in terms of local ACPA levels, smoking and lung abnormalities on HRCT. These findings strengthen the link between mucosal ACPA responses and the lungs in RA.

Identification of Subclinical Lung Involvement in ACPA-Positive Subjects through Functional Assessment and Serum Biomarkers

Lung involvement is related to the natural history of anti-citrullinated proteins antibodies (ACPA)-positive rheumatoid arthritis (RA), both during the pathogenesis of the disease and as a site of disease-related injury. Increasing evidence suggests that there is a subclinical, early lung involvement during the course of the disease, even before the onset of articular manifestations, which can potentially progress to a symptomatic interstitial lung disease. To date, reliable, non-invasive markers of subclinical lung involvement are still lacking in clinical practice. The aim of this study is to evaluate the diagnostic potential of functional assessment and serum biomarkers in the identification of subclinical lung involvement in ACPA-positive subjects. Fifty ACPA-positive subjects with or without confirmed diagnosis of RA (2010 ARC-EULAR criteria) were consecutively enrolled. Each subject underwent clinical evaluation, pulmonary function testing (PFT) with assessment of diffusion lung capacity for carbon monoxide (DL_CO), cardiopulmonary exercise testing (CPET), surfactant protein D (SPD) serum levels dosage and high-resolution computed tomography (HRCT) of the chest. The cohort was composed of 21 ACPA-positive subjects without arthritis (ND), 10 early (disease duration < 6 months, treatment-naïve) RA (ERA) and 17 long-standing (disease duration < 36 months, on treatment) RA (LSRA). LSRA patients had a significantly higher frequency of overall HRCT abnormalities compared to the other groups (p = 0.001). SPD serum levels were significantly higher in ACPA-positive subjects compared with healthy controls (158.5 ± 132.3 ng/mL vs 61.27 ± 34.11 ng/mL; p < 0.0001) and showed an increasing trend from ND subjects to LSRD patients (p = 0.004). Patients with HRCT abnormalities showed significantly lower values of DL_CO (74.19 ± 13.2% pred. vs 131.7 ± 93% pred.; p = 0.009), evidence of ventilatory inefficiency at CPET and significantly higher SPD serum levels compared with subjects with no HRCT abnormalities (213.5 ± 157.2 ng/mL vs 117.7 ± 157.3 ng/mL; p = 0.018). Abnormal CPET responses and higher SPD levels were also associated with specific radiological findings. Impaired DL_CO and increased SPD serum levels were independently associated with the presence of HRCT abnormalities. Subclinical lung abnormalities occur early in RA-associated autoimmunity. The presence of subclinical HRCT abnormalities is associated with several functional abnormalities and increased SPD serum levels of SPD. Functional evaluation through PFT and CPET, together with SPD assessment, may have a diagnostic potential in ACPA-positive subjects, contributing to the identification of those patients to be referred to HRCT scan.

Clinical implications of ANCA positivity in idiopathic pulmonary fibrosis patients

The diagnostic process of idiopathic interstitial pneumonias (IIPs) is complex and the underlying mechanisms that participate in these diseases still need to be fully understood. In 2015, the European Respiratory Society/American Thoracic Society Task Force on Undifferentiated Forms of Connective Tissue Disease-Associated Interstitial Lung Disease introduced the term “interstitial pneumonia with autoimmune features” (IPAF) to identify subjects with IIP and features suggesting background autoimmunity but not characterisable connective tissue disease (CTD) [1]. The need for a proper clinical, serological and morphological assessment of IIP was highlighted to identify potential subjects with IPAF and CTD-ILD. However, the measurement of anti-neutrophil cytoplasmic antibodies (ANCAs) is not included in the definition of IPAF and ANCA serological testing is only recommended in idiopathic pulmonary fibrosis (IPF) when a clinical suspicion of vasculitis exists [2]. As current research evaluates the prognostic relevance of autoimmune features in IIP, the clinical importance of ANCA positivity still needs to be determined.

ANCA positivity is uncommon in North American IPF patients. However, women with IPF who areMPO-positive have a considerable risk for developing clinical manifestations of vasculitis.http://bit.ly/2RlsQNP

Anti-carbamylated proteins antibody repertoire in rheumatoid arthritis: evidence of a new autoantibody linked to interstitial lung disease

OBJECTIVE

To analyse the association between anti-carbamylated protein antibodies (Anti-CarP) and interstitial lung disease (ILD) in rheumatoid arthritis (RA) patients.

METHODS

Cross-sectional study including RA patients fulfilling the 2010 ACR/EULAR criteria. The main population comprised two groups: (1) RA patients diagnosed with RA-ILD (RA-ILD group); (2) RA patients without ILD (non-ILD RA group). Non-ILD RA patients in whom ILD was suspected underwent a diagnostic work-up and, if ILD was diagnosed, were switched to the RA-ILD group. ILD was diagnosed by high-resolution computed tomography and confirmed by a multidisciplinary committee. An independent replication sample was also obtained. Three Anti-CarP IgG autoantibodies against fetal calf serum (Anti-FCS), fibrinogen (Anti-Fib) and chimeric fibrine/filagrine homocitrullinated peptide (Anti-CFFHP) and one Anti-CarP IgA against FCS (Anti-FCS-IgA) were determined by home-made ELISA. Associations between Anti-CarP and ILD were analysed using multivariable logistic regression adjusted by smoking, sex, age, RA disease duration, rheumatoid factor and anticitrullinated protein antibodies.

RESULTS

We enrolled 179 patients: 37 (21%) were finally diagnosed with RA-ILD. Anti-CarP specificities were more frequent in RA-ILD patients (Anti-FCS 70% vs 43%; Anti-Fib 73% vs 51%; Anti-CFFHP 38% vs 19%; Anti-CarP-IgA 51% vs 20%, p<0.05 for all comparisons). Serum titers of Anti-CarP were significantly higher in RA-ILD patients. Anti-CarP specificities showed a robust effect towards increasing the odds of ILD in the multivariate analysis (Anti-FCS (OR: 3.42; 95% CI: 1.13 to 10.40), Anti-Fib (OR: 2.85; 95% CI: 0.83 to 9.70), Anti-CFFHP (OR: 3.11; 95% CI: 1.06 to 9.14) and Anti-FCS-IgA (OR: 4.30; 95% CI: 1.41 to 13.04)). Similar findings were observed in the replication sample.

CONCLUSIONS

Anti-CarP were strongly associated with ILD. The role of homocitrullination in RA-ILD merits further investigation.

IgA Antibodies Directed Against Citrullinated Protein Antigens Are Elevated in Patients With Idiopathic Pulmonary Fibrosis

BACKGROUND

The etiology of idiopathic pulmonary fibrosis (IPF) is unknown. Because it shares genetic, histopathologic, and radiographic features with the fibrosing interstitial lung disease seen in rheumatoid arthritis (RA), the goal of this study was to investigate RA-related autoantibodies in IPF.

METHODS

The study included patients with IPF from two separate cohorts at National Jewish Health and Brigham Women's Hospital (n = 181), general population control subjects (n = 160), and control subjects with disease (n = 86 [40 with RA-usual interstitial pneumonia and 46 with hypersensitivity pneumonitis]). Serum was tested for RA-associated antibodies (including IgG and IgA) to citrullinated protein antigens (ACPA). Lung tissue in 11 patients with IPF was examined for ectopic lymphoid aggregates.

RESULTS

An increased prevalence of ACPA positivity was found in two separate IPF cohorts. In particular, positivity for IgA-ACPA was increased in these two IPF cohorts compared with general population control subjects (21.3% and 24.8% vs 5.6%; P < .01). Patients with IPF were more likely to be IgA-ACPA-positive than IgG-ACPA-positive (23.2% vs 8.3%; P < .01), whereas patients with RA were more likely to be IgG-ACPA-positive than IgA-ACPA-positive (72.5% vs 52.5%; P = .04). There was a strong correlation between IgA-ACPA level and the number of ectopic lymphoid aggregates on lung histologic examination in IPF (r = 0.72; P = .01).

CONCLUSIONS

In this study, IgA-ACPA was elevated in patients with IPF and correlated with lymphoid aggregates in the lung, supporting the theory that IgA-ACPA may play a role in lung disease pathogenesis in a subset of individuals with IPF. Future studies are needed to determine whether this subset of ACPA-positive patients with IPF is distinct from patients with IPF but without antibodies.

CXCL16/CXCR6 axis promotes bleomycin-induced fibrotic process in MRC-5 cells via the PI3K/AKT/FOXO3a pathway

OBJECTIVE

Interstitial lung disease (ILD) is a progressive and irreversible lung disease with very limited therapeutic options. Previous studies have found that chemokine ligands CXCL16 and CXCR6 play critical roles in organ fibrosis. However, whether CXCL16 and CXCR6 are also involved in the pathogenesis of ILD, as well as their regulatory role in pulmonary fibrosis, has not been reported.

METHODS

In this study, we detected CXCL16 levels in patients with rheumatoid arthritis-associated ILD (RA-ILD) and examined the critical role of the CXCL16/CXCR6 axis in the proliferation and collagen production of human pulmonary fibroblasts (MRC-5 cells). The effect of anti-CXCL16 antibody on the bleomycin-induced fibrogenesis in cultured MRC-5 cells was also evaluated.

RESULTS

Our results indicated that serum soluble CXCL16 was significantly higher in RA-ILD patients and also associated with the severity of lung fibrosis. CXCL16 facilitates fibrosis by enhancing proliferation, migration, and collagen production of MRC-5 cells. Furthermore, a synergistic fibrogenic effect of CXCL16 and bleomycin has been found. CXCL16 stimulated the activation of PI3K/AKT/FOXO3a signaling pathway in MRC-5 cells, and the inhibition by specific inhibitors Wortmannin and LY294002, or knockdown of CXCR6 by siRNA also suppressed the biological functions of MRC-5 cells mediated by CXCL16. Similarly, down-regulation of CXCR6 also partly blocked BLM-induced fibrogenesis in MRC-5 cells.

CONCLUSIONS

CXCL16/CXCR6 axis promotes proliferation and collagen production of MRC-5 cells by the PI3K/AKT/FOXO3a signaling pathway, and inhibition of the CXCL16/CXCR6 axis may provide a new therapeutic strategy targeting pulmonary fibrosis.

Current Perspectives On Emerging Biomarkers For Rheumatoid Arthritis-Associated Interstitial Lung Disease

Rheumatoid arthritis (RA) is a common systemic autoimmune disease whose fibro-inflammatory manifestations may affect a number of tissues and organs, including the lungs. In fact, interstitial lung disease (ILD) is a leading cause of mortality among patients with RA. RA-related interstitial lung disease (RA-ILD) most often presents in an injury pattern called usual interstitial pneumonia (UIP), which portends a relatively worse prognosis than other less commonly occurring patterns of RA-ILD, like non-specific interstitial pneumonia (NSIP). Biomarkers from serum or bronchoalveolar lavage fluid could aid in the identification of patients at risk for RA-ILD, the detection of patients most likely to develop the UIP pattern of RA-ILD, and the prediction of disease behaviour over time. Notably, the use of highly sensitive serologic biomarkers, including rheumatoid factor (RF) and antibodies targeting cyclic citrullinated peptides, while somewhat specific for RA joint disease, have only limited utility as biomarkers for RA-ILD. Candidate biomarkers for RA-ILD include these and other autoantibodies as well as certain genes and molecules that hold promise as biomarkers in other forms of ILD. In this manuscript, we summarize the state of knowledge on biomarkers for the development and progression of RA-ILD.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Mechanisms of lung disease development in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disorder that causes joint inflammation and damage. Extra-articular manifestations occur in many patients and can include lung involvement in the form of airway or parenchymal inflammation and fibrosis. Although the pathophysiology of articular RA has been extensively investigated, the mechanisms causing airway and parenchymal lung disease are not well defined. Infections, cigarette-smoking, mucosal dysbiosis, host genetics and premature senescence are all potentially important contributors to the development of lung disease in patients with RA. RA-associated lung disease (which can predate the onset of articular disease by many years) probably originates from chronic airway and alveolar epithelial injury that occurs in an individual with a genetic background that permits the development of autoimmunity, leading to chronic inflammation and subsequent airway and lung parenchymal remodelling and fibrosis. Further investigations into the specific mechanisms by which lung disease develops in RA will be crucial for the development of effective therapies. Identifying mechanisms by which environmental and host factors cooperate in the induction of autoimmunity in the lung might also help to establish the order of early events in RA.

Rheumatoid Arthritis Disease Activity Predicting Incident Clinically Apparent Rheumatoid Arthritis-Associated Interstitial Lung Disease: A Prospective Cohort Study

OBJECTIVE

To evaluate rheumatoid arthritis (RA) disease activity and risk of RA-associated interstitial lung disease (RA-ILD).

METHODS

We investigated disease activity and risk of RA-ILD using the Brigham RA Sequential Study (BRASS, 2003-2016). All patients were diagnosed as having RA according to accepted criteria. Disease Activity Scores in 28 joints (DAS28) and covariate data were measured prospectively at annual study visits. Diagnosis of RA-ILD was determined by review of images from clinically indicated chest computed tomography scans. We analyzed patients without RA-ILD at baseline. We used Cox regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for RA-ILD, using annually updated DAS28 data, with adjustment for known RA-ILD risk factors (age, sex, smoking status, RA duration, and serologic status). We performed alternative analyses that did not censor at the time of missing DAS28 data and included adjustment for use of methotrexate, use of glucocorticoids, presence of bone erosions, and presence of rheumatoid nodules.

RESULTS

Among 1,419 participants, the mean ± SD age was 55.8 ± 14.2 years, and 68.6% were seropositive for either cyclic citrullinated peptide or rheumatoid factor. We identified 85 incident cases of RA-ILD during a mean ± SD follow-up duration of 8.9 ± 4.2 years per patient. The moderate/high disease activity group had a multivariable HR of 2.22 (95% CI 1.28-3.82) for RA-ILD compared to the remission/low disease activity group. Risk of RA-ILD increased across disease activity categories: multivariable HR 1.00 (reference) for remission, 1.41 (95% CI 0.61-3.28) for low disease activity, 2.08 (95% CI 1.06-4.05) for moderate disease activity, and 3.48 (95% CI 1.64-7.38) for high disease activity (P for trend = 0.001). For each unit increase in the DAS28, the risk of RA-ILD increased by 35% (95% CI 14-60%). Results were similar in analyses that included follow-up for missing DAS28 data and with adjustment for use of methotrexate, use of glucocorticoids, presence of bone erosions, or presence of rheumatoid nodules.

CONCLUSION

Active articular RA was associated with an increased risk of developing RA-ILD. These results suggest that decreasing systemic inflammation may alter the natural history of RA-ILD development.

Thoracic Manifestations of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is commonly associated with pulmonary disease that can affect any anatomic compartment of the thorax. The most common intrathoracic manifestations of RA include interstitial lung disease, airway disease, pleural disease, rheumatoid nodules, and drug-induced toxicity. Patients with RA with thoracic involvement often present with nonspecific respiratory symptoms, although many are asymptomatic. Therefore, clinicians should routinely consider pulmonary disease when evaluating any patient with RA, particularly one with known risk factors. The optimal screening, diagnostic, and treatment strategies for RA-associated pulmonary disease remain uncertain and are the focus of ongoing investigation.

Extra-articular Manifestations and Comorbidity in Rheumatoid Arthritis: Potential Impact of Pre-Rheumatoid Arthritis Prevention

Rheumatoid arthritis (RA) is associated with a wide variety of extra-articular manifestations and comorbidities, several of which can be organ- or even life-threatening. These extra-articular manifestations and comorbidities can also contribute to the physical disability and psychological morbidity of RA that lead to reduced quality of life, higher direct and indirect costs, and societal burden of the disease. Although the expansion of RA treatment options and adoption of treat-to-target approaches has reduced the incidence and severity of several nonarticular manifestations of RA, such as rheumatoid vasculitis and cardiovascular disease events, this does not seem to be shared by all RA comorbidities. Moreover, a number of highly prevalent and impactful RA-driven comorbidities, such as accelerated atherosclerosis, interstitial lung disease, and sarcopenia, can present clinically in the years before the manifestation of joint pain or observable synovitis. A larger proportion of patients with RA have atherosclerosis, myocardial dysfunction, interstitial lung disease, and sarcopenia that is subclinical in the preclinical and earliest clinical phases of RA, emphasizing the importance of targeting the pre-RA phase for the prevention of comorbidities that are often poorly responsive to treatment once they develop. Herein, we review the potential impact of pre-RA prevention on the incidence and burden of extra-articular manifestations and nonarticular comorbidities.

Clinical characteristics associated with occurrence and poor prognosis of interstitial lung disease in rheumatoid arthritis

BACKGROUND/AIMS

To analyze clinical characteristics of interstitial lung disease (ILD) associated with rheumatoid arthritis (RA), especially in patients with poor prognosis.

METHODS

Seventy-seven RA patients with ILD and 231 age, sex, and disease duration-matched RA patients without ILD were enrolled in this retrospective study. Epidemiologic, clinical, and laboratory information were obtained through a medical chart review. Logistic regression analysis was used to estimate the risk of mortality in RA patients with ILD.

RESULTS

Compared to the RA without ILD group, the RA with ILD group had significantly higher titers of rheumatoid factor and the anti-cyclic citrullinated peptide (p = 0.001 for both), higher levels of C-reactive protein (CRP) at the time of RA diagnosis (p = 0.014), and a higher erythrocyte sedimentation rate (p = 0.022) and CRP levels (p < 0.001) throughout the 10-year follow-up period. These patients also received a higher mean daily dose of corticosteroids (p < 0.001). In the subgroup analysis of RA patients with ILD, 28 patients (36.4%) died during follow-up. Multivariate analysis revealed that older age at the time of ILD diagnosis was significantly associated with mortality. Usual interstitial pneumonia (UIP) subtype on high-resolution computed tomography (HRCT) was also suggested as a poor prognostic factor.

CONCLUSION

The survival of RA patients with ILD is adversely affected by age at the time of ILD diagnosis. RA-ILD patients diagnosed after age 65 or with a UIP subtype on HRCT may have a poor prognosis.

Elevated anti-cyclic citrullinated peptide antibody titer is associated with increased risk for interstitial lung disease

This paper is to examine the relationship between anti-cyclic citrullinated peptide (anti-CCP) antibody titers and the development of interstitial lung disease (ILD) in patients with and without rheumatoid arthritis (RA). A retrospective investigation was conducted on all adult patients tested for anti-CCP between January 1, 2007, and December 31, 2012, in a university healthcare system. Patients with specified exposures or conditions known to cause ILD were excluded. The prevalence of ILD was compared between those with and without a positive CCP. The study population was then divided into four titer groups based on anti-CCP titers: negative, low titer, moderate titer, high titer. Fisher's exact tests compared the prevalence of ILD among the anti-CCP titer groups. Multivariate logistic regression examined the association between anti-CCP and ILD while controlling for confounders. These analyses were repeated in two subgroups: a "confirmed RA" subgroup and an "unconfirmed RA" subgroup. Two thousand and thirty patients met inclusion criteria and 453 of those had confirmed RA. Progressively higher anti-CCP titer groups developed an increasingly higher prevalence of ILD (p < 0.01). When adjusting for age, tobacco, and a diagnosis of RA, higher anti-CCP titer groups continued to correlate with an increased prevalence of ILD (OR 1.47, 95% CI 1.10-1.96, p < 0.001). This study is the first to show that progressively higher anti-CCP titers correlate with increasing prevalence of ILD, even when adjusting for confounders.

Autoantibodies to Peptidylarginine Deiminase 2 Are Associated With Less Severe Disease in Rheumatoid Arthritis

Objective: Peptidylarginine deiminases (PAD) 2 and 4 are key enzymes in rheumatoid arthritis (RA) pathogenesis due to their ability to generate the protein targets of anti-citrullinated protein antibodies (ACPA). Anti-PAD4 antibodies that cross-react with PAD3 (anti-PAD3/4) have been identified and are associated with severe joint and lung disease. Here, we examined whether anti-PAD2 antibodies were present in patients with RA and defined their clinical significance. Patients and Methods: A PAD2 ELISA was established to screen for anti-PAD2 IgG in sera from RA patients from a prospective observational cohort study (n = 184) and healthy controls (n = 100). RA patient characteristics were compared according to anti-PAD2 antibody status. Multivariable models were constructed to explore the independent associations of anti-PAD2 antibodies with clinical variables. Results: Anti-PAD2 antibodies were found in 18.5% of RA patients and 3% of healthy controls (p < 0.001). Among RA patients, anti-PAD2 antibodies were not associated with traditional genetic or serologic RA risk factors, including HLA-DRβ1 shared epitope alleles, ACPA, rheumatoid factor (RF), or anti-PAD3/4 antibodies. In addition, antibodies to PAD2 were associated with fewer swollen joints, a lower prevalence of interstitial lung disease, and less progression of joint damage. In subset analyses in which patients were stratified by the baseline presence of ACPA/RF or anti-PAD3/4 antibodies, anti-PAD2 antibodies provided additional value in identifying patients with the least progressive joint disease. Conclusions: Anti-PAD2 antibodies represent a novel serologic marker in RA that identifies a genetically and clinically unique subset of patients with less severe joint and lung disease.

Interleukin-18 is associated with the presence of interstitial lung disease in rheumatoid arthritis: a cross-sectional study

OBJECTIVE

Serum interleukin-18 (IL-18) levels are increased in patients with interstitial lung disease (ILD). In addition, IL-18 levels are increased in patients with rheumatoid arthritis (RA) and are associated with arthritis activity. We determined whether increased IL-18 levels are associated with ILD in RA.

METHOD

RA patients were enrolled using an RA cohort database. Plasma IL-18 levels were measured by enzyme-linked immunosorbent assay. ILD was determined by a pulmonologist and a radiologist based on chest radiography and computed tomography findings. IL-18 levels for RA with ILD and RA without ILD were compared. Associations between ILD and various markers including IL-18 and confounding factors (e.g. smoking history) were investigated by logistic regression analysis. Diagnostic values of IL-18 for the presence of ILD were investigated using receiver operating characteristics curve analysis.

RESULTS

ILD was complicated in 8.2% (n = 26) of the study population (N = 312). Plasma IL-18 levels were higher for RA patients with ILD than for RA patients without ILD (721.0 ± 481.4 vs 436.8 ± 438.9 pg/mL, p < 0.001). IL-18, Krebs von den Lungen-6, and anti-cyclic citrullinated peptide antibody titre and glucocorticoid doses were independently associated with the presence of ILD during multivariate logistic regression analysis. Sensitivity and specificity of IL-18 levels for the detection of ILD in RA patients were 65.3% and 76.3%, respectively (area under the curve = 0.73).

CONCLUSION

Plasma IL-18 levels were higher for RA patients with ILD than for those without ILD. Increased IL-18 levels were associated with the presence of ILD.

Comorbidities in rheumatic arthritis

Objectives

Rheumatoid arthritis (RA) is one of the most common systemic inflammatory diseases, but its etiology is still not fully known. The aim of this preliminary study was to assess what particular comorbidities are involved in the progression of RA and determine the influence that the aforementioned diseases have on each other.

Material and methods

Forty patients with diagnosed RA according to EULAR/ACR criteria from 2010 were included in the study. The majority of the group was female (n = 35; 87.5%). Patients were tested using routine laboratory and imaging methods allowing diagnosis and assessment of disease activity. Dual energy X-ray absorptiometry was also evaluated for mineral density. The activity of the disease was assessed using the disease activity score DAS28 (ESR) and SDAI (Simplified Disease Activity Index).

Results

Among studied patients, based on the DAS28 index, 9 patients were in the remission phase (22.5%) and 12 (30%) had high disease activity. Increased values of CRP were observed in the majority of patients (65%). The group analysis demonstrated the most common comorbidities in patients with RA, as follows: hypertension (n = 14; 35%) and osteoporosis or osteopenia (n = 13; 32.6%).

Conclusions

Patients with rheumatoid arthritis (RA) are more susceptible to developing hypertension and osteoporosis. We did not observe a significant association between other comorbidities and activity of RA. The next study will assess a larger number of patients.

Lung Involvements in Rheumatic Diseases: Update on the Epidemiology, Pathogenesis, Clinical Features, and Treatment

Lung illness encountered in patients with rheumatic diseases bears clinical significance in terms of increased morbidity and mortality as well as potential challenges placed on patient care. Although our understanding of natural history of this important illness is still limited, epidemiologic knowledge has been accumulated during the past decade to provide useful information on the risk factors and prognosis of lung involvements in rheumatic diseases. Moreover, the pathogenesis particularly in the context of genetics has been greatly updated for both the underlying rheumatic disease and associated lung involvement. This review will focus on the current update on the epidemiologic and genetics features and treatment options of the lung involvements associated with four major rheumatic diseases (rheumatoid arthritis, systemic sclerosis, myositis, and systemic lupus erythematosus), with more attention to a specific form of involvement or interstitial lung disease.

Aggregatibacter actinomycetemcomitans-induced hypercitrullination links periodontal infection to autoimmunity in rheumatoid arthritis

A bacterial etiology of rheumatoid arthritis (RA) has been suspected since the beginnings of modern germ theory. Recent studies implicate mucosal surfaces as sites of disease initiation. The common occurrence of periodontal dysbiosis in RA suggests that oral pathogens may trigger the production of disease-specific autoantibodies and arthritis in susceptible individuals. We used mass spectrometry to define the microbial composition and antigenic repertoire of gingival crevicular fluid in patients with periodontal disease and healthy controls. Periodontitis was characterized by the presence of citrullinated autoantigens that are primary immune targets in RA. The citrullinome in periodontitis mirrored patterns of hypercitrullination observed in the rheumatoid joint, implicating this mucosal site in RA pathogenesis. Proteomic signatures of several microbial species were detected in hypercitrullinated periodontitis samples. Among these, Aggregatibacter actinomycetemcomitans (Aa), but not other candidate pathogens, induced hypercitrullination in host neutrophils. We identified the pore-forming toxin leukotoxin A (LtxA) as the molecular mechanism by which Aa triggers dysregulated activation of citrullinating enzymes in neutrophils, mimicking membranolytic pathways that sustain autoantigen citrullination in the RA joint. Moreover, LtxA induced changes in neutrophil morphology mimicking extracellular trap formation, thereby releasing the hypercitrullinated cargo. Exposure to leukotoxic Aa strains was confirmed in patients with RA and was associated with both anticitrullinated protein antibodies and rheumatoid factor. The effect of human lymphocyte antigen-DRB1 shared epitope alleles on autoantibody positivity was limited to RA patients who were exposed to Aa These studies identify the periodontal pathogen Aa as a candidate bacterial trigger of autoimmunity in RA.

Practical Management of Respiratory Comorbidities in Patients with Rheumatoid Arthritis

Lung disease is one of the most common causes of extra-articular morbidity and mortality in patients with rheumatoid arthritis (RA). Development of pulmonary manifestations may be due to the systemic disease itself; to serious respiratory adverse events such as pneumonitis and infections secondary to therapy; or to lifestyle habits such as smoking. Rheumatologists often need to make important treatment decisions and plan future care in RA patients with respiratory comorbidities, despite the absence of clear evidence or consensus. In this review we evaluate the clinical assessment and management of RA-associated interstitial lung disease, bronchiectasis, serious (including opportunistic) infection, and smoking-related diseases. We summarize the international recommendations for the management of such conditions where available, refer to published best practice on the basis of scientific literature, and propose practical management suggestions to aid informed decision-making.

Anti-citrullinated peptides antibodies in systemic sclerosis: Meta-analysis of frequency and meaning

OBJECTIVES

Diagnosis of systemic sclerosis (SSc) is partially determined by the presence of specific autoantibodies often associated with specific clinical features. Recent studies report the presence of ACPA in SSc. We aimed to evaluate the prevalence of ACPA in SSc and to assess their influence on clinical presentation of SSc.

METHODS

A systematic literature search was performed using PubMed and Cochrane databases' publications between 1999 and March 2017. Search terms were: "systemic sclerosis [MeSH] AND (ACPA OR anti-CCP OR rheumatoid factor OR cohort OR value diagnostic)". In a first step, we selected cohorts with >50 SSc patients with ACPA identification, for ACPA frequency determination. In a second step, we included studies that analysed clinical profiles according to ACPA status. Meta-analyses were performed when at least two studies were available.

RESULTS

First, we identified 13 observational studies with a total of 1231 SSc patients. The mean prevalence of ACPA in SSc was 9.2%. Secondly, we identified nine studies reporting clinical aspects according to ACPA status. Our meta-analyses showed a significant association between ACPA positivity and the presence of arthritis (odds ratio (OR)=22.48 [10.71-47.21]), joint erosions seen on X-rays (OR=14.79 [6.38-34.28]), pulmonary fibrosis (OR=2.75 [1.21-6.24]), oesophagus involvement (OR=2.72 [1.05-7.07]), and diffuse skin involvement (OR=2.21 [1.21-4.03]).

CONCLUSIONS

The prevalence of ACPA in scleroderma is 9.2%. Our meta-analysis shows an increased risk for erosive arthritis, pulmonary fibrosis, oesophagus involvement and diffuse skin involvement, in patients with ACPA-positive SSc. ACPA should be systematically included in SSc assessment.

Rheumatoid Arthritis-Associated Interstitial Lung Disease: Current Concepts

PURPOSE OF REVIEW

Among the many extra-articular complications of rheumatoid arthritis (RA), interstitial lung disease (ILD) contributes significantly to morbidity and mortality. Prevalence estimates for RA-ILD vary widely depending on the specific clinical, radiographic, and functional criteria used to establish the diagnosis. A key unresolved issue is whether early, subclinical forms of RA-ILD represent a precursor to end stage, fibrotic lung disease. Based on uncertainties surrounding the natural history of RA-ILD, incomplete understanding of underlying disease pathogenesis, and lack of controlled clinical trials, evidence-based therapeutic strategies remain largely undefined.

RECENT FINDINGS

Correlative clinico-epidemiological studies have identified key risk factors for disease progression. Complementing these findings, the identification of specific molecular and serological markers of RA-ILD has improved our understanding of disease pathogenesis and established the foundation for predictive biomarker profiling. Experience from case series and cohort studies suggests that newer biological agents such as rituximab may be viable treatment options. RA-ILD continues to have a major impact on "disease intrinsic" morbidity and mortality. Increased understanding of disease pathogenesis and the natural history of subclinical RA-ILD will promote the development of more refined therapeutic strategies.

Anti -citrullinated peptide antibodies profiling in established rheumatoid arthritis

OBJECTIVES

Anti-citrullinated protein/peptide antibodies (ACPA) represent an important tool for the diagnosis of rheumatoid arthritis (RA) and the presence of multiple ACPA specificities is highly correlated with the evolution towards RA. However, little is known about the association of single specificities with disease manifestations and response to therapy in established RA. The aim of this work is to evaluate in a retrospective study the clinico-serological association of ACPA detected using VCP1 and VCP2 (EBV-derived citrullinated peptides) and HCP1 and HCP2 (histone-H4-derived citrulinated peptides) in established RA.

METHODS

In 413 RA patients, anti-VCP1, -VCP2, -HCP1, -HCP2 were measured by ELISA. Patients were evaluated for systemic involvement, disease activity/severity, ongoing and past therapies. Data were analyzed by cluster analysis (CA) and principal component analysis (PCA).

RESULTS

Anti-VCP1 were detected in 44% of RA patients; anti-VCP2 in 52%; anti-HCP1 in 46% and anti-HCP2 in 63%. CA and PCA independently demonstrated that ACPA levels are associated with RF positivity, and lung involvement. Subdividing patients in 5 groups according to the number of anti-peptide antibodies, mean antibody level and RF positivity, as well as the frequency of lung involvement, progressively increase in parallel with the number of ACPA specificities.

CONCLUSIONS

Higher number/levels of ACPA subtypes is associated with lung involvement but not with erosive disease. Moreover, a broader ACPA repertoire may identify patients treated with biological therapy, probably affected by a more severe disease. In conclusion, ACPA typing might be relevant for a better characterization of some disease features in established RA.

Phenome-Wide Association Study of Autoantibodies to Citrullinated and Noncitrullinated Epitopes in Rheumatoid Arthritis

OBJECTIVE

Patients with rheumatoid arthritis (RA) develop autoantibodies against a spectrum of antigens, but the clinical significance of these autoantibodies is unclear. Using a phenome-wide association study (PheWAS) approach, we examined the association between autoantibodies and clinical subphenotypes of RA.

METHODS

This study was conducted in a cohort of RA patients identified from the electronic medical records (EMRs) of 2 tertiary care centers. Using a published multiplex bead assay, we measured 36 autoantibodies targeting epitopes implicated in RA. We extracted all International Classification of Diseases, Ninth Revision (ICD-9) codes for each subject and grouped them into disease categories (PheWAS codes), using a published method. We tested for the association of each autoantibody (grouped by the targeted protein) with PheWAS codes. To determine significant associations (at a false discovery rate [FDR] of ≤0.1), we reviewed the medical records of 50 patients with each PheWAS code to determine positive predictive values (PPVs).

RESULTS

We studied 1,006 RA patients; the mean ± SD age of the patients was 61.0 ± 12.9 years, and 79.0% were female. A total of 3,568 unique ICD-9 codes were grouped into 625 PheWAS codes; the 206 PheWAS codes with a prevalence of ≥3% were studied. Using the PheWAS method, we identified 24 significant associations of autoantibodies to epitopes at an FDR of ≤0.1. The associations that were strongest and had the highest PPV for the PheWAS code were autoantibodies against fibronectin and obesity (P = 6.1 × 10^-4 , PPV 100%), and that between fibrinogen and pneumonopathy (P = 2.7 × 10^-4 , PPV 96%). Pneumonopathy codes included diagnoses for cryptogenic organizing pneumonia and obliterative bronchiolitis.

CONCLUSION

We demonstrated application of a bioinformatics method, the PheWAS, to screen for the clinical significance of RA-related autoantibodies. Using the PheWAS approach, we identified potentially significant links between variations in the levels of autoantibodies and comorbidities of interest in RA.

Lung Manifestations in the Rheumatic Diseases

Lung ailments in rheumatic diseases present unique challenges for diagnosis and management and are a source of significant morbidity and mortality for patients. Unlike the idiopathic interstitial pneumonias, patients with rheumatic diseases experience lung disease in the context of a systemic disease that may make it more difficult to recognize and that may present greater risks with treatment. Despite recent advances in our awareness of these diseases, there is still a significant lack of understanding of natural history to elucidate which patients will have disease that is progressive and thus warrants treatment. What we do know is that a subset of patients with rheumatic disease experience parenchymal lung disease that can prognostically resemble idiopathic pulmonary fibrosis, such as in rheumatoid arthritis, and that others can have aggressive inflammatory lung disease in the context of autoimmune myositis, systemic sclerosis, or an undifferentiated autoimmune process. As we enter into a paradigm shift where we view lung health as a cornerstone of our care of patients with rheumatic diseases, we hopefully will improve our ability to identify those patients at highest risk for pulmonary disease and progression, and offer emerging treatments which will result in better outcomes and a better quality of life.

Role of Autoantibodies in the Diagnosis of Connective-Tissue Disease ILD (CTD-ILD) and Interstitial Pneumonia with Autoimmune Features (IPAF)

The diagnosis of interstitial lung disease (ILD) requires meticulous evaluation for an underlying connective tissue disease (CTD), with major implications for prognosis and management. CTD associated ILD (CTD-ILD) occurs most commonly in the context of an established CTD, but can be the first and/or only manifestation of an occult CTD or occur in patients who have features suggestive of an autoimmune process, but not meeting diagnostic criteria for a defined CTD-recently defined as "interstitial pneumonia with autoimmune features" (IPAF). The detection of specific autoantibodies serves a critical role in the diagnosis of CTD-ILD, but there remains a lack of data to guide clinical practice including which autoantibodies should be tested on initial assessment and when or in whom serial testing should be performed. The implications of detecting autoantibodies in patients with IPAF on disease behaviour and management remain unknown. The evaluation of CTD-ILD is challenging due to the heterogeneity of presentations and types of CTD and ILD that may be encountered, and thus it is imperative that immunologic tests are interpreted in conjunction with a detailed rheumatologic history and examination and multidisciplinary collaboration between respiratory physicians, rheumatologists, immunologists, radiologists and pathologists.

Modeling using clinical examination indicators predicts interstitial lung disease among patients with rheumatoid arthritis

Interstitial lung disease (ILD) is a severe extra-articular manifestation of rheumatoid arthritis (RA) that is well-defined as a chronic systemic autoimmune disease. A proportion of patients with RA-associated ILD (RA-ILD) develop pulmonary fibrosis (PF), resulting in poor prognosis and increased lifetime risk. We investigated whether routine clinical examination indicators (CEIs) could be used to identify RA patients with high PF risk. A total of 533 patients with established RA were recruited in this study for model building and 32 CEIs were measured for each of them. To identify PF risk, a new artificial neural network (ANN) was built, in which inputs were generated by calculating Euclidean distance of CEIs between patients. Receiver operating characteristic curve analysis indicated that the ANN performed well in predicting the PF risk (Youden index = 0.436) by only incorporating four CEIs including age, eosinophil count, platelet count, and white blood cell count. A set of 218 RA patients with healthy lungs or suffering from ILD and a set of 87 RA patients suffering from PF were used for independent validation. Results showed that the model successfully identified ILD and PF with a true positive rate of 84.9% and 82.8%, respectively. The present study suggests that model integration of multiple routine CEIs contributes to identification of potential PF risk among patients with RA.

Biologics-induced interstitial lung diseases in rheumatic patients: facts and controversies

INTRODUCTION

Interstitial lung disease (ILD) is a common, devastating pulmonary complication. An increased number of reports suggesting that biological disease modifying antirheumatic drugs (DMARDs) induced or exacerbated ILDs in rheumatoid arthritis (RA) patients has garnered increased attention. Areas covered: This article discusses ILDs induced by or exacerbated during biological therapy in RA patients. The article summarizes the efficacy and safety of a variety of licensed and off-label biologics clinically used for rheumatic diseases, focusing on the onset or exacerbation of RA-associated ILDs (RA-ILDs) in RA patients treated with biologics targeting tumor necrosis factor, CD20, interleukin 1 (IL-1) and IL-6 receptors. Additionally, the pathogenesis of RA-ILDs is discussed. Expert opinion: To some extent, the possibility of biologic-induced RA-ILDs increases the difficulty in choosing an optimal regimen for RA treatment with biological agents, as the relationship between biological therapy safety and the induction or exacerbation of RA-ILDs has not been established. A framework to assess baseline disease severity, particularly standardizing the evaluation of the pulmonary condition stage in RA patients and monitoring the outcome during the biological therapy treatment, is highly needed and may substantially help guide treatment decisions and predict the treatment benefits.

NETosis as Source of Autoantigens in Rheumatoid Arthritis

In neutrophils (but also in eosinophils and in mast cells), different inflammatory stimuli induce histone deimination, chromatin decondensation, and NET formation. These web-like structures that trap and kill microbes contain DNA, cationic granule proteins, and antimicrobial peptides, but the most abundant proteins are core histones. Histones contained in NETs have been deiminated, and arginines are converted in citrullines. While deimination is a physiological process amplified in inflammatory conditions, only individuals carrying genetic predisposition to develop rheumatoid arthritis (RA) make antibodies to deiminated proteins. These antibodies, collectively identified as anti-citrullinated proteins/peptides antibodies (ACPA), react with different deiminated proteins and display partially overlapping specificities. In this paper, we will summarize current evidence supporting the role of NETosis as critical mechanism in the breach of tolerance to self-antigens and in supporting expansion and differentiation of autoreactive cells. In fact, several lines of evidence connect NETosis with RA: RA unstimulated synovial fluid neutrophils display enhanced NETosis; sera from RA patients with Felty's syndrome bind deiminated H3 and NETs; a high number of RA sera bind deiminated H4 contained in NETs; human monoclonal antibodies generated from RA synovial B cells decorate NETs and bind deiminated histones. In RA, NETs represent on one side an important source of autoantigens bearing posttranslational modifications and fueling the production of ACPA. On the other side, NETs deliver signals that maintain an inflammatory milieu and contribute to the expansion and differentiation of ACPA-producing B cells.

Rheumatoid arthritis-associated autoantibodies and subclinical interstitial lung disease: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Adults with interstitial lung disease (ILD) often have serologic evidence of autoimmunity of uncertain significance without overt autoimmune disease. We examined associations of rheumatoid arthritis (RA)-associated antibodies with subclinical ILD in community-dwelling adults.

METHODS

We measured serum rheumatoid factor (RF) and anticyclic citrullinated peptide antibody (anti-CCP) and high attenuation areas (HAAs; CT attenuation values between -600 and -250 Hounsfield units) on cardiac CT in 6736 community-dwelling US adults enrolled in the Multi-Ethnic Study of Atherosclerosis. We measured interstitial lung abnormalities (ILAs) in 2907 full-lung CTs at 9.5-year median follow-up. We used generalised linear and additive models to examine associations between autoantibodies and both HAA and ILA, and tested for effect modification by smoking.

RESULTS

In adjusted models, HAA increased by 0.49% (95% CI 0.11% to 0.86%) per doubling of RF IgM and by 0.95% (95% CI 0.50% to 1.40%) per RF IgA doubling. ILA prevalence increased by 11% (95% CI 3% to 20%) per RF IgA doubling. Smoking modified the associations of both RF IgM and anti-CCP with both HAA and ILA (interaction p values varied from 0.01 to 0.09). Among ever smokers, HAA increased by 0.81% (95% CI 0.33% to 1.30%) and ILA prevalence increased by 14% (95% CI 5% to 24%,) per RF IgM doubling; and HAA increased by 1.31% (95% CI 0.45% to 2.18%) and ILA prevalence increased by 13% (95% CI 2% to 24%) per anti-CCP doubling. Among never smokers, no meaningful associations were detected.

CONCLUSIONS

RA-related autoimmunity is associated with both quantitative and qualitative subclinical ILD phenotypes on CT, particularly among ever smokers.

Connective tissue disease-related interstitial lung disease

Interstitial lung disease (ILD) is commonly present in patients with an underlying connective tissue disease (CTD), particularly those with systemic sclerosis, rheumatoid arthritis, and inflammatory myositis. The clinical spectrum can range from asymptomatic findings on imaging to respiratory failure and death. Distinguishing features in the clinical, radiographic, and histopathologic characteristics of CTD-ILD subsets can predict prognosis and treatment response. Treatment often consists of combinations of immunosuppressive medications, but there is a paucity of guidance in the literature to help clinicians determine appropriate screening and management of CTD-ILD. As such, there is a critical need for studies that can elucidate the natural history of the CTD-ILD, as well as clarify optimal therapies for CTD patients with ILD.

The lung in rheumatoid arthritis, cause or consequence?

PURPOSE OF REVIEW

Recent discoveries implicate the lungs as a possible extra-articular mucosal site for initiating rheumatoid arthritis-associated immunity.

RECENT FINDINGS

Individuals at risk for developing arthritis and patients with early untreated rheumatoid arthritis show signs of lung involvement on high-resolution computer tomography. Rheumatoid arthritis-associated antibodies are present in patients with respiratory complains such as bronchiectasis and unexplained dyspnea even in the absence of joint disease and might predict future development of rheumatoid arthritis in these patients. Rheumatoid arthritis-associated antibodies are detected in the sputum of individuals at risk for developing rheumatoid arthritis but not yet having disease. Signs of bronchial mucosal inflammation with germinal center formation and local production of antibodies have been described in patients with early untreated rheumatoid arthritis. Shared antigenic targets have been identified and characterized in the lungs and joints of rheumatoid arthritis patients.

SUMMARY

Recent findings support an important role for the lung as a mucosal extra-articular place were inflammation induced by external triggers (such as smoking) leads to tolerance break and generation of rheumatoid arthritis-specific immunity already before disease onset with only secondary targeting of the joints.

Smoking and Subclinical ILD in RA versus the Multi-Ethnic Study of Atherosclerosis

A population-based cohort showed an association between cigarette smoking and subclinical parenchymal lung disease defined as regions of increased computed tomography (CT) lung densitometry. This technique has not been applied to the rheumatoid arthritis (RA) population where associated ILD is highly prevalent. The association between cumulative cigarette smoking and volume of areas of high attenuation (HAA: >-600 and <-250 Hounsfield Units) on full inspiratory CT was compared in 172 RA participants and 3,969 controls in a general population sample. Multivariable regression models were used to adjust for demography, anthropometrics, percent emphysema, and CT parameters. The mean cumulative cigarette smoking exposure was 25 (IQR 10–42) and 15(IQR 5–31) pack-years for the RA and non-RA cohorts, respectively. Mean HAA was 153(±57) cm³ and 129(±50) cm³ in the RA and non-RA cohorts, respectively. Each 10 cigarette pack-year increment was associated with a higher HAA by 0.03% (95% CI, 0.007–0.05%) in RA patients and by 0.008% (95% CI, 0.003–0.01%) in those without RA (interaction p = 0.001). Cigarette smoking was associated with higher lung attenuation; with a magnitude of association more pronounced in those with RA than in the general population. These data suggest that cigarette smoking may be a more potent ILD risk factor for RA patients than in the general population.