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

CXCL10 as a biomarker of interstitial lung disease in patients with rheumatoid arthritis

INTRODUCTION

Pulmonary involvement is a frequent and serious rheumatoid arthritis (RA) manifestation that affects 60%-80% of patients. CXCL10 is an inflammatory chemokine that regulates different biological responses, such as chemotaxis, angiogenesis, and inflammation.

AIM

This study aimed to identify the role of CXCL10 as a peripheral blood marker of RA-ILD and its correlation with disease activity.

PATIENTS AND METHODS

This cross-sectional study included 73 patients with RA (33 with ILD and 40 without ILD). Pulmonary function tests and high-resolution computed tomography were performed. Blood samples were taken for complete blood count and blood chemistry analysis, and human interferon-inducible protein 10 (IP-10/CXCL10) level. Statistical Package for the Social Sciences (version 22) was used for all statistical calculations.

RESULTS

The serum CXCL10 level and patient age (r=.393, p=.024), disease duration (r=.756, p<0.001), erythrocyte sedimentation rate (r=.516, p=.002), C-reactive protein (r=.539, p=.001), and rheumatoid factor (r=.663, p<.001) revealed a significant positive correlation. Furthermore, the Modified Health Assessment Questionnaire (r=-.418, p=.015) revealed a significant negative correlation. Patients with RA-ILD show significantly higher CXCL10 than those without ILD (p<.001).

CONCLUSION

CXCL10 is a useful RA disease activity biomarker and is an RA-ILD-sensitive biomarker, also CXCL10 is a significant predictor for development of RA-ILD.

Rheumatoid arthritis, quantitative parenchymal lung features, and mortality among smokers

OBJECTIVES

There have been limited investigations of the prevalence and mortality impact of quantitative computed tomography (QCT) parenchymal lung features in rheumatoid arthritis (RA). We examined the cross-sectional prevalence and mortality associations of QCT features, comparing RA and non-RA participants.

METHODS

We identified participants with and without RA in COPDGene, a multicentre cohort study of current or former smokers. Using a k-nearest neighbor quantifier, high resolution CT chest scans were scored for percentage of normal lung, interstitial changes, and emphysema. We examined associations between QCT features and RA using multivariable linear regression. After dichotomizing participants at the 75th percentile for each QCT feature among non-RA participants, we investigated mortality associations by RA/non-RA status and quartile 4 vs quartiles 1-3 of QCT features using Cox regression. We assessed for statistical interactions between RA and QCT features.

RESULTS

We identified 82 RA cases and 8820 non-RA comparators. In multivariable linear regression, RA was associated with higher percentage of interstitial changes (β = 1.7 ± 0.5, p= 0.0008) but not emphysema (β = 1.3 ± 1.7, p= 0.44). Participants with RA and >75th percentile of emphysema had significantly higher mortality than non-RA participants (HR 5.86, 95%CI 3.75-9.13) as well as RA participants (HR 5.56, 95%CI 2.71-11.38) with ≤75th percentile of emphysema. There were statistical interactions between RA and emphysema for mortality (multiplicative p= 0.014; attributable proportion 0.53, 95%CI 0.30-0.70).

CONCLUSIONS

Using machine learning-derived QCT data in a cohort of smokers, RA was associated with higher percentage of interstitial changes. The combination of RA and emphysema conferred >5-fold higher mortality.

Prevalence and mortality associations of interstitial lung abnormalities in rheumatoid arthritis within a multicentre prospective cohort of smokers

OBJECTIVE

To investigate the prevalence and mortality impact of interstitial lung abnormalities (ILAs) in RA and non-RA comparators.

METHODS

We analysed associations between ILAs, RA, and mortality in COPDGene, a multicentre prospective cohort study of current and past smokers, excluding known interstitial lung disease (ILD) or bronchiectasis. All participants had research chest high-resolution CT (HRCT) reviewed by a sequential reading method to classify ILA as present, indeterminate or absent. RA cases were identified by self-report RA and DMARD use; non-RA comparators had neither an RA diagnosis nor used DMARDs. We examined the association and mortality risk of RA and ILA using multivariable logistic regression and Cox regression.

RESULTS

We identified 83 RA cases and 8725 non-RA comparators with HRCT performed for research purposes. ILA prevalence was 16.9% in RA cases and 5.0% in non-RA comparators. After adjusting for potential confounders, including genetics, current/past smoking and other lifestyle factors, ILAs were more common among those with RA compared with non-RA [odds ratio 4.76 (95% CI 2.54, 8.92)]. RA with ILAs or indeterminate for ILAs was associated with higher all-cause mortality compared with non-RA without ILAs [hazard ratio (HR) 3.16 (95% CI 2.11, 4.74)] and RA cases without ILA [HR 3.02 (95% CI 1.36, 6.75)].

CONCLUSIONS

In this cohort of smokers, RA was associated with ILAs and this persisted after adjustment for current/past smoking and genetic/lifestyle risk factors. RA with ILAs in smokers had a 3-fold increased all-cause mortality, emphasizing the importance of further screening and treatment strategies for preclinical ILD in RA.

Assessing predictors of rheumatoid arthritis-associated interstitial lung disease using quantitative lung densitometry

OBJECTIVE

To assess predictors of subclinical RA-associated interstitial lung disease (RA-ILD) using quantitative lung densitometry (qLD).

METHODS

RA patients underwent multi-detector row CT scanning at baseline and after an average of 39 months. Scans were analysed with qLD for the percentage of lung parenchyma with high attenuation areas (%HAA: the percentage of voxels of -600 to -250 Hounsfield units). Additionally, a pulmonary radiologist calculated an expert radiologist scoring (ERS) for RA-ILD features. Generalized linear models were used to identify indicators of baseline %HAA and predictors of %HAA change.

RESULTS

Baseline %HAA was assessed in 193 RA patients and 106 had repeat qLD assessment. %HAA was correlated with ERS (Spearman's rho = 0.261; P < 0.001). Significant indicators of high baseline %HAA (>10% of lung parenchyma with high attenuation) included female sex, higher pack-years of smoking, higher BMI and anti-CCP ≥200 units, collectively contributing an area under the receiver operator curve of 0.88 (95% CI 0.81, 0.95). Predictors of %HAA increase, occurring in 49% with repeat qLD, included higher baseline %HAA, presence of mucin 5B (MUC5B) minor allele and absence of HLA-DRB1 shared epitope (area under the receiver operator curve = 0.69; 95% CI 0.58, 0.79). The association of the MUC5B minor allele with %HAA change was higher among men and those with higher cumulative smoking. Within the group with increased %HAA, anti-CCP level was significantly associated with a greater increase in %HAA.

CONCLUSIONS

%HAA, assessed with qLD, was linked to several known risk factors for RA-ILD and may represent a more quantitative method to identify RA-ILD and track progression than expert radiologist interpretation.

High-resolution computed tomography of the lung in patients with rheumatoid arthritis: Prevalence of interstitial lung disease involvement and determinants of abnormalities

An international consensus for rheumatoid arthritis (RA) patients at risk of developing interstitial lung disease (ILD) is still lacking. The aims of study were to evaluate: the prevalence of ILD involvement in RA over high-resolution computed tomography (HRCT); the relationships between pulmonary function tests (PFTs), patient-centered measurements, and ILD; and the potential risk factors contributing to RA-ILD patients.Data regarding the clinical characteristics (age, sex, age at onset of RA), laboratory findings (rheumatoid factor [RF] and anti-citrullinated protein antibodies [ACPA]), respiratory functional assessment (forced vital capacity [FVC] and carbon monoxide diffusion capacity [DLCO]), patient-centred measures of dyspnea (PCMD), Health Assessment Questionnaire-Disability Index (HAQ-DI), and HRCT have collected retrospectively. HRCT abnormalities were evaluated using a conventional visual reader-based score (CoVR) and a computer-aided method (CaM). The relationships between the 2 HRCT scores-PFTs and PCMD-were calculated using Pearson correlation. The area under the receiving-operating characteristic (AUC-ROC) curve was calculated to determine the discriminatory performance of measurements between patients with and without ILD. The multivariate regression model was used to evaluate the association force between ILD and RA characteristics.In all, 151 patients (45 males and 106 females, mean age 53.4 ± 7.6 years) were included. ILD had been detected in 29 patients out of 151 (19.2%). Usual interstitial pneumonia was the most common HRCT. RA-ILD patients were older, and older at RA onset (both P < .01), with a higher HAQ-DI (P < .05) than patients without ILD. ACPA positivity and titer were higher in the RA-ILD group (P = .02). Extent and severity of ILD, and total CoVR and CaM score closely related to DLCO and PCMD (both P < .0001). A reduced DLCO was the most sensitive test for predicting the presence of ILD on HRCT (AUC-ROC 0.811 ± 0.037). Advanced age (P < .0001), age at RA onset (P = .025), ACPA titer (P = .004), and smoking (P = .008) were independent explanatory variables of HRCT damage in multivariate analysis.The RA-ILD is associated with age and older age of RA onset, smoking, and ACPA titer. DLCO seems to be the most sensitive parameter to predict ILD on HRCT, followed by PCMD.

Development of a risk indicator score for the identification of interstitial lung disease in patients with rheumatoid arthritis

BACKGROUND

Clinically evident interstitial lung disease (ILD) affects 10%-42% of RA patients with prognostic implications. The aim of this study was to discern which factors are associated with the presence of ILD in RA patients and to develop a score that could help to stratify the risk of having ILD in RA patients.

METHODS

Case-control study. We included RA patients recruited from ILD and rheumatology clinics. We retrieved the following data: gender, age, presence of extra articular manifestations, disease activity scores, antibodies status, ESR, and medication use. Multivariate logistic regression was performed. A risk indicator score was developed.

RESULTS

Of 118 patients included in this study, 52 (44%) had RA-ILD (cases) and 66 (56%) had RA without ILD (controls). Twenty-six patients were male (22%), the mean age was 56.6±15.6 years. Five variables were significantly associated with the presence of ILD: male gender, smoking, extraarticular manifestations, a CDAI score>28, and ESR>80mm/h. The AUC of the final model curve was 0.86 (95%CI 0.79-0.92). Two potential cut-off points of the risk indicator score were chosen: a value of 2 points showed a sensitivity of 90.38% and a specificity of 63.64%, while a value of 4 points showed a sensitivity of 51.9% and a specificity of 90.9%.

CONCLUSION

This study identified risk factors that could help identify which RA patients are at risk of having ILD through the development of a risk indicator score. This score needs to be validated in an independent cohort.

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.

Investigation of key autophagy-and mitophagy-related proteins and gene expression in BALF cells from patients with IPF and RA-ILD

Idiopathic pulmonary fibrosis (IPF) is a chronic and irreversible interstitial lung disease with a poor prognosis and limited therapeutic options. Over the past decade, research efforts have focused on the pathogenetic mechanisms involved in this enigmatic lung disease. Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease often complicated by the development of interstitial lung disease (ILD), leading to high mortality and morbidity. Autophagy is a process regulating the turnover of subcellular components and organelles, and represents a major cellular homeostatic mechanism. Recent evidence suggests a role of autophagy and mitochondrial dysfunction in the development of IPF, focusing on lung fibroblasts and epithelial cells. The aim of this study was to examine the mRNA levels of molecules involved inthe autophagy pathway in bronchoalveolar lavage fluid (BALF)-derived cellsfrom patients with IPF in comparison topatients with RA demonstrating lung involvement (ILD) by RT-qPCR. The significant upregulation of BECLIN1 was observed in patients with RA-ILD compared with those with IPF. Other genes involved in the autophagy pathway were also examined, such as Unc-51 like autophagy activating kinase 1 (ULK1), BCL2 interacting protein 3 (BNIP3) and p62. No differences in the mRNA expression levels of these genes were observed. As regards the selective degradation of mitochondria and mitophagy, similar PTEN-induced putative kinase 1 (PINK1) and PARKIN; E3 ubiquitin ligase (PRKN) expression, as well as PINK1 protein levels, were observed. On the whole, the findings of this study demonstrate an increased expression of BECLIN1 in BALF cells from patients with RA-ILD compared with those from patients with IPF, while similar levels in other key molecules implicating in the autophagy pathway were observed in patients with IPF and RA-ILD.

Upregulation of citrullination pathway: From Autoimmune to Idiopathic Lung Fibrosis

Background

Increased protein citrullination and peptidylarginine deiminases (PADIs), which catalyze the citrullination process, are central in Rheumatoid arthritis pathogenesis and probably involved in the initial steps towards autoimmunity. Approximately, 10% of RA patients develop clinically significantly ILD. A possible shared role of protein citrullination in rheumatoid arthritis associated interstitial lung disease (RA-ILD), and idiopathic pulmonary fibrosis (IPF) pathogenesis remains unclear.

Methods

We evaluated PADI2 and PADI4 mRNA expression in bronchoalveolar lavage fluid (BALF) cells of 59 patients with IPF, 27 patients RA-ILD and 10 healthy controls. PADI 2 and 4 expression was analyzed by western blot and immunohistochemistry. Citrullinated protein levels were also quantified.

Results

PADI4 mRNA and protein levels were higher in RA-ILD and IPF than controls. Furthermore, PADI4 mRNA levels showed an increase among smokers in RA-ILD. PADI4 expression was detected in granulocytes and macrophages in all groups, with the strongest cytoplasmic expression observed in granulocytes in RA-ILD and IPF. PADI2 mRNA and immunostaining of BAL cells, were similar in all groups among smokers. Overall, stronger staining was observed in current smokers. Citrullinated peptides were significantly increased in IPF compared to RA-ILD and controls. In RA-ILD, protein citrullination strongly correlated with PADI4 expression and anti-citrullinated protein antibodies (ACPAs).

Conclusions

These results suggest that the citrullination pathway is upregulated in IPF and in RA-ILD.

Electronic supplementary material

The online version of this article (10.1186/s12931-017-0692-9) contains supplementary material, which is available to authorized users.

Air pollution and subclinical interstitial lung disease: the Multi-Ethnic Study of Atherosclerosis (MESA) air-lung study

We studied whether ambient air pollution is associated with interstitial lung abnormalities (ILAs) and high attenuation areas (HAAs), which are qualitative and quantitative measurements of subclinical interstitial lung disease (ILD) on computed tomography (CT).We performed analyses of community-based dwellers enrolled in the Multi-Ethnic Study of Atherosclerosis (MESA) study. We used cohort-specific spatio-temporal models to estimate ambient pollution (fine particulate matter (PM_2.5), nitrogen oxides (NO_x), nitrogen dioxide (NO₂) and ozone (O₃)) at each home. A total of 5495 participants underwent serial assessment of HAAs by cardiac CT; 2671 participants were assessed for ILAs using full lung CT at the 10-year follow-up. We used multivariable logistic regression and linear mixed models adjusted for age, sex, ethnicity, education, tobacco use, scanner technology and study site.The odds of ILAs increased 1.77-fold per 40 ppb increment in NO_x (95% CI 1.06 to 2.95, p = 0.03). There was an overall trend towards an association between higher exposure to NO_x and greater progression of HAAs (0.45% annual increase in HAAs per 40 ppb increment in NO_x; 95% CI -0.02 to 0.92, p = 0.06). Associations of ambient fine particulate matter (PM_2.5), NO_x and NO₂ concentrations with progression of HAAs varied by race/ethnicity (p = 0.002, 0.007, 0.04, respectively, for interaction) and were strongest among non-Hispanic white people.We conclude that ambient air pollution exposures were associated with subclinical ILD.

Recent advances in the pathogenesis, prediction, and management of rheumatoid arthritis-associated interstitial lung disease

PURPOSE OF REVIEW

To provide an overview of recently published articles covering interstitial lung disease associated with rheumatoid arthritis (RA-ILD).

RECENT FINDINGS

Over the past year, many studies replicated previous findings in more diverse and occasionally larger populations internationally. Specifically, the association among cigarette smoking, high rheumatoid factor titer, elevated anticitrullinated protein antibody (ACPA) levels, and RA-ILD was strengthened. Clinical characteristics, autoantibodies, and biomarkers to aid in RA-ILD development, progression, and mortality prediction were explored. Finally, direct and indirect treatment effects were highlighted.

SUMMARY

The ability to identify risk factors for preclinical RA-ILD has been enhanced, but the proper management strategy for these patients is yet to be defined. ACPAs and cigarette smoking are highly associated with RA-ILD, but the mechanistic relationship between lung injury and autoantibody generation remains unknown. There is conflicting evidence regarding the significance of a usual interstitial pneumonia (UIP) versus non-UIP pattern on high-resolution computed tomography. The use of biologic agents in patients with rheumatoid arthritis does not appear to increase the risk of incident ILD or RA-ILD exacerbation. Randomized prospective studies of specific therapy for RA-ILD are still lacking.