Rheumatoid Arthritis-Associated Interstitial Lung Disease: Current Concepts

Impact of DMARD treatment and systemic inflammation on all-cause mortality in patients with rheumatoid arthritis and interstitial lung disease: a cohort study from the German RABBIT register

OBJECTIVES

To investigate the impact of disease activity and treatment with disease-modifying antirheumatic drugs (DMARDs) on all-cause mortality in patients with rheumatoid arthritis and prevalent interstitial lung disease (RA-ILD).

METHODS

Patients with RA-ILD were selected from the biologics register Rheumatoid Arthritis: Observation of Biologic Therapy (RABBIT). Using time-varying Cox regression, the association between clinical measures and mortality was investigated. The impact of DMARDs was analysed by (1) Cox regression considering cumulative exposure (ie, treatment months divided by total months) and (2) time-varying Cox regression as main approach (treatment exposures at monthly level).

RESULTS

Out of 15 566 participants, 381 were identified as RA-ILD cases with 1258 person-years of observation and 2.6 years median length of follow-up. Ninety-seven patients (25.5%) died and 34 (35.1%) of these were not receiving DMARD therapy at the time of death. Higher inflammatory biomarkers but not swollen and tender joint count were significantly associated with mortality. Compared with tumour necrosis factor inhibitors (TNFi), non-TNFi biologic DMARDs (bDMARDs) exhibited adjusted HRs (aHRs) for mortality below 1, lacking statistical significance. This finding was stable in various sensitivity analyses. Joint aHR for non-TNFi biologics and JAKi versus TNFi was 0.56 (95% CI 0.33 to 0.97). Receiving no DMARD treatment was associated with a twofold higher mortality risk compared with receiving any DMARD treatment, aHR 2.03 (95% CI 1.23 to 3.35).

CONCLUSIONS

Inflammatory biomarkers and absence of DMARD treatment were associated with increased risk of mortality in patients with RA-ILD. Non-TNFi bDMARDs may confer enhanced therapeutic benefits in patients with RA-ILD.

PM10 increases mortality risk in rheumatoid arthritis-associated interstitial lung disease

OBJECTIVES

The effect of air pollution on the prognosis of rheumatoid arthritis-associated interstitial lung disease (RA-ILD) remains poorly understood. We aimed to evaluate the effect of long-term exposure to particulate matter with an aerodynamic diameter of ≤10 µm (PM10) and nitrogen dioxide (NO2) on mortality in patients with RA-ILD.

METHODS

We included 309 patients (mean age, 61.7 years; male, 44.3%) with RA-ILD. Individual-level long-term exposures to PM10 and NO2 at their residential addresses were estimated using a national-scale exposure prediction model. The effect of the two air pollutants on mortality was estimated using a Cox-proportional hazards model adjusted for individual-level and area-level characteristics.

RESULTS

The median follow-up period was 4.8 years, and 40.8% of patients died or underwent lung transplantation. The annual average concentrations of PM10 and NO2 were 56.3 μg/m3 and 22.4 ppb, respectively. When air pollutant levels were stratified by quartiles, no association was observed between air pollutant concentration and mortality in patients with RA-ILD. However, when stratified by two groups (high exposure (top 25th percentile) vs low exposure (bottom 75th percentile)), we observed a significant association between high PM10 exposure and mortality (HR 1.68; 95% CI 1.11 to 2.52; p=0.013) but no association between NO2 exposure and mortality. In the subgroup analyses, the effect of high PM10 exposure on mortality was significant in patients aged <65 years (HR 1.98; 95% CI 1.02 to 3.85; p=0.045).

CONCLUSIONS

Our results indicated that high PM10 exposure may be associated with mortality in patients with RA-ILD.

Targeting Progression in Pulmonary Fibrosis: An Overview of Underlying Mechanisms, Molecular Biomarkers, and Therapeutic Intervention

Interstitial lung diseases comprise a heterogenous range of diffuse lung disorders, potentially resulting in pulmonary fibrosis. While idiopathic pulmonary fibrosis has been recognized as the paradigm of a progressive fibrosing interstitial lung disease, other conditions with a progressive fibrosing phenotype characterized by a significant deterioration of the lung function may lead to a burden of significant symptoms, a reduced quality of life, and increased mortality, despite treatment. There is now evidence indicating that some common underlying biological mechanisms can be shared among different chronic fibrosing disorders; therefore, different biomarkers for disease-activity monitoring and prognostic assessment are under evaluation. Thus, understanding the common pathways that induce the progression of pulmonary fibrosis, comprehending the diversity of these diseases, and identifying new molecular markers and potential therapeutic targets remain highly crucial assignments. The purpose of this review is to examine the main pathological mechanisms regulating the progression of fibrosis in interstitial lung diseases and to provide an overview of potential biomarker and therapeutic options for patients with progressive pulmonary fibrosis.

Prevalence and clinical characteristics of patients with rheumatoid arthritis with interstitial lung disease using unstructured healthcare data and machine learning

OBJECTIVES

Real-world data regarding rheumatoid arthritis (RA) and its association with interstitial lung disease (ILD) is still scarce. This study aimed to estimate the prevalence of RA and ILD in patients with RA (RAILD) in Spain, and to compare clinical characteristics of patients with RA with and without ILD using natural language processing (NLP) on electronic health records (EHR).

METHODS

Observational case-control, retrospective and multicentre study based on the secondary use of unstructured clinical data from patients with adult RA and RAILD from nine hospitals between 2014 and 2019. NLP was used to extract unstructured clinical information from EHR and standardise it into a SNOMED-CT terminology. Prevalence of RA and RAILD were calculated, and a descriptive analysis was performed. Characteristics between patients with RAILD and RA patients without ILD (RAnonILD) were compared.

RESULTS

From a source population of 3 176 165 patients and 64 241 683 EHRs, 13 958 patients with RA were identified. Of those, 5.1% patients additionally had ILD (RAILD). The overall age-adjusted prevalence of RA and RAILD were 0.53% and 0.02%, respectively. The most common ILD subtype was usual interstitial pneumonia (29.3%). When comparing RAILD versus RAnonILD patients, RAILD patients were older and had more comorbidities, notably concerning infections (33.6% vs 16.5%, p<0.001), malignancies (15.9% vs 8.5%, p<0.001) and cardiovascular disease (25.8% vs 13.9%, p<0.001) than RAnonILD. RAILD patients also had higher inflammatory burden reflected in more pharmacological prescriptions and higher inflammatory parameters and presented a higher in-hospital mortality with a higher risk of death (HR 2.32; 95% CI 1.59 to 2.81, p<0.001).

CONCLUSIONS

We found an estimated age-adjusted prevalence of RA and RAILD by analysing real-world data through NLP. RAILD patients were more vulnerable at the time of inclusion with higher comorbidity and inflammatory burden than RAnonILD, which correlated with higher mortality.

Usefulness of Lung Ultrasound as a Method for Early Diagnosis of Interstitial Lung Disease in Patients with Rheumatoid Arthritis

Purpose

To determine the value of lung ultrasound (LUS) compared to high-resolution computed tomography (HRCT) in the early diagnosis of interstitial lung disease (ILD) in patients with rheumatoid arthritis (RA).

Patients and Methods

An observational prospective study was performed. Were included patients with respiratory symptoms or/and, patients with crackles in auscultation during medical consultation. All patients underwent to chest X-rays, LUS, HRCT,and respiratory function tests.

Results

A total of 192 patients with RA were included. Mean disease duration was 16.8 ± 11.1 years. 72% were positive for rheumatoid factor or anti-citrullinated antibodies. Of the total number of subjects, 54.7% had respiratory symptoms. The other patients did not have respiratory symptoms, but they did have had crackles on pulmonary auscultation. B lines > 11.5 on the ROC curve predicted ILD (AUC 0.63; CI 95%: 0.55-0.71; p < 0.003). A DLCO value of <7.13 significantly predicted the presence of ILD (AUC 0.61; 95% CI: 0.52-0.70; p < 0.028).

Conclusion

The findings of this study suggest that LUS is a valuable tool for the early diagnosis of ILD in patients with RA, and together with DLCO, can adequately predict the presence of ILD in this population. LUS also helps to determine which patients with respiratory symptoms and signs suggestive for ILD are undergo to HRCT.

Enhancing the identification of rheumatoid arthritis-associated interstitial lung disease through text mining of chest computerized tomography reports

OBJECTIVES

Algorithms have been developed to identify rheumatoid arthritis-interstitial lung disease (RA-ILD) in administrative data with positive predictive values (PPVs) between 70 and 80%. We hypothesized that including ILD-related terms identified within chest computed tomography (CT) reports through text mining would improve the PPV of these algorithms in this cross-sectional study.

METHODS

We identified a derivation cohort of possible RA-ILD cases (n = 114) using electronic health record data from a large academic medical center and performed medical record review to validate diagnoses (reference standard). ILD-related terms (e.g., ground glass, honeycomb) were identified in chest CT reports by natural language processing. Administrative algorithms including diagnostic and procedural codes as well as specialty were applied to the cohort both with and without the requirement for ILD-related terms from CT reports. We subsequently analyzed similar algorithms in an external validation cohort of 536 participants with RA.

RESULTS

The addition of ILD-related terms to RA-ILD administrative algorithms increased the PPV in both the derivation (improvement ranging from 3.6 to 11.7%) and validation cohorts (improvement 6.0 to 21.1%). This increase was greatest for less stringent algorithms. Administrative algorithms including ILD-related terms from CT reports exceeded a PPV of 90% (maximum 94.6% derivation cohort). Increases in PPV were accompanied by a decline in sensitivity (validation cohort -3.9 to -19.5%).

CONCLUSIONS

The addition of ILD-related terms identified by text mining from chest CT reports led to improvements in the PPV of RA-ILD algorithms. With high PPVs, use of these algorithms in large data sets could facilitate epidemiologic and comparative effectiveness research in RA-ILD.

Clinical characteristics of rheumatoid arthritis patients with interstitial lung disease: baseline data of a single-center prospective cohort

BACKGROUND

To introduce a prospective cohort for rheumatoid arthritis (RA) patients with interstitial lung disease (ILD) and to identify their clinical features in comparison with RA patients without ILD.

METHODS

Using a multidisciplinary collaborative approach, a single-center cohort for RA patients with ILD (RA-ILD) was established in May 2017, and enrolment data from May 2017 to March 2021 were used to compare the clinical features of RA patients without ILD (RA-non ILD). Multivariable logistic regression analysis was used to identify factors associated with ILD in RA patients.

RESULTS

Among 148 RA-ILD and 410 RA-non ILD patients, participants in the RA-ILD group were older (65.8 ± 9.9 vs. 58.0 ± 10.4 years, P < 0.001) and included more males (35.8% vs. 14.6%, P < 0.001) than in the RA-non ILD group. The RA-ILD group had a higher proportion of late-onset RA patients (age ≥ 60 years) than in the comparator group (43.9% vs. 14.2%, P < 0.001). Multivariable logistic regression analysis showed that higher age at RA onset (OR 1.056, 95% CI 1.021-1.091), higher body mass index (BMI; OR 1.65, 95% CI 1.036-2.629), smoking history (OR 2.484, 95% CI 1.071-5.764), and oral glucocorticoid use (OR 3.562, 95% CI 2.160-5.874) were associated with ILD in RA patients, whereas methotrexate use was less likely to be associated with ILD (OR 0.253, 95% CI 0.155-0.412).

CONCLUSIONS

Higher age at RA onset, smoking history, and higher BMI were associated with the presence of ILD among RA patients. Oral glucocorticoids were more frequently used whereas methotrexate was less likely to be used in RA-ILD patients.

Childhood Interstitial Lung Disease

Childhood interstitial lung disease (chILD) is a heterogeneous group of diseases with various clinical and imaging findings. The incidence and prevalence have increased in recent years, probably due to better comprehension of these rare diseases and increased awareness among physicians. chILDs present with nonspecific pulmonary symptoms, such as tachypnea, hypoxemia, cough, rales, and failure to thrive. Unnecessary invasive procedures can be avoided if specific mutations are detected through genetic examinations or if typical imaging patterns are recognized on computed tomography. Disease knowledge and targeted therapies are improving through international collaboration. Pulmonary involvement in systemic diseases is not uncommon. Pulmonary involvement may be the first finding in connective tissue diseases. This review aims to present a systematic patient-targeted approach to the diagnosis of chILD.

Treatment Outcomes for Rheumatoid Arthritis-Associated Interstitial Lung Disease: A Real-World, Multisite Study of the Impact of Immunosuppression on Pulmonary Function Trajectory

BACKGROUND

Rheumatoid arthritis (RA)-associated interstitial lung disease (ILD) is common in patients with RA and leads to significant morbidity and mortality. No randomized, placebo-controlled data are available that support the role of immunosuppression to treat RA-associated ILD, despite being widely used in clinical practice.

RESEARCH QUESTION

How does immunosuppression impact pulmonary function trajectory in a multisite retrospective cohort of patients with RA-associated ILD?

STUDY DESIGN AND METHODS

Patients with RA who started treatment for ILD with mycophenolate, azathioprine, or rituximab were identified retrospectively from five ILD centers. Change in lung function before and after treatment was analyzed using a linear spline mixed-effect model with random intercept. Prespecified secondary analyses examined the impact of radiologic pattern of ILD (ie, usual interstitial pneumonia [UIP] vs non-UIP) on treatment trajectory.

RESULTS

Two hundred twelve patients were included in the analysis: 92 patients (43.4%) were treated with azathioprine, 77 patients (36.3%) were treated with mycophenolate mofetil, and 43 patients (20.3%) were treated with rituximab. In the combined analysis of all three agents, an improvement in FVC % predicted was found after 12 months of treatment compared with the potential 12-month response without treatment (+3.90%; P ≤ .001; 95% CI, 1.95-5.84). Diffusing capacity of the lungs for carbon monoxide (Dlco) % predicted also improved at 12 months (+4.53%; P ≤ .001; 95% CI, 2.12-6.94). Neither the UIP pattern of ILD nor choice of immunosuppressive agent significantly impacted the pulmonary function trajectory on immunosuppression.

INTERPRETATION

Immunosuppression was associated with an improved trajectory in FVC and Dlco compared with the pretreatment pulmonary function trajectory. Prospective, randomized trials are required to validate these findings.

Novel tracers for molecular imaging of interstitial lung disease: A state of the art review

Interstitial lung disease is an overarching term for a wide range of disorders characterized by inflammation and/or fibrosis in the lungs. Most prevalent forms, among others, include idiopathic pulmonary fibrosis (IPF) and connective tissue disease associated interstitial lung disease (CTD-ILD). Currently, only disease modifying treatment options are available for IPF and progressive fibrotic CTD-ILD, leading to reduction or stabilization in the rate of lung function decline at best. Management of these patients would greatly advance if we identify new strategies to improve (1) early detection of ILD, (2) predicting ILD progression, (3) predicting response to therapy and (4) understanding pathophysiology. Over the last years, positron emission tomography (PET) and single photon emission computed tomography (SPECT) have emerged as promising molecular imaging techniques to improve ILD management. Both are non-invasive diagnostic tools to assess molecular characteristics of an individual patient with the potential to apply personalized treatment. In this review, we encompass the currently available pre-clinical and clinical studies on molecular imaging with PET and SPECT in IPF and CTD-ILD. We provide recommendations for potential future clinical applications of these tracers and directions for future research.

Sex and Gender in Lung Disease and Sleep Disorders: A State-of-the-Art Review

The terms sex and gender often are used interchangeably, but have specific meaning when it comes to their effects on lung disease. Ample evidence is now available that sex and gender affect the incidence, susceptibility, presentation, diagnosis, and severity of many lung diseases. Some conditions are more prevalent in women, such as asthma. Other conditions are seen almost exclusively in women, like lymphangioleiomyomatosis. Some life stages-such as pregnancy-are unique to women and can affect the onset and course of lung disease. Clinical presentation may differ as well, such as higher number of exacerbations experienced by women with COPD and greater cardiovascular morbidity in women with sleep-disordered breathing. In addition, response to therapy and medication safety may also differ by sex, and yet, pharmacogenomic factors often are not addressed adequately in clinical trials. Various aspects of lung and sleep biology and pathobiology are impacted by female sex and female reproductive transitions. Differential gene expression or organ development can be impacted by these biological differences. Understanding these differences is the first step in moving toward precision medicine for women. This article is a state-of-the-art review of specific effects of sex and gender focused on epidemiology, disease presentation, risk factors, and management of lung diseases. Pathobiological mechanisms explaining sex differences in these diseases are beyond the scope of this article. We review the literature and focus on recent guidelines about using sex and gender in research. We also review sex and gender differences in lung diseases.

Novel Biomarkers, Diagnostic and Therapeutic Approach in Rheumatoid Arthritis Interstitial Lung Disease-A Narrative Review

Rheumatoid arthritis (RA) is considered a systemic inflammatory disease marked by polyarthritis which affects the joints symmetrically, leading to progressive damage of the bone structure and eventually joint deformity. Lung involvement is the most prevalent extra-articular feature of RA, affecting 10-60% of patients with this disease. In this review, we aim to discuss the patterns of RA interstitial lung disease (ILD), the molecular mechanisms involved in the pathogenesis of ILD in RA, and also the therapeutic challenges in this particular extra-articular manifestation. The pathophysiology of RA-ILD has been linked to biomarkers such as anti-citrullinated protein antibodies (ACPAs), MUC5B mutation, Krebs von den Lungen 6 (KL-6), and other environmental factors such as smoking. Patients at the highest risk for RA-ILD and those most likely to advance will be identified using biomarkers. The hope is that finding biomarkers with good performance characteristics would help researchers better understand the pathophysiology of RA-ILD and, in turn, lead to the development of tailored therapeutics for this severe RA manifestation.

Plumbagin relieves rheumatoid arthritis through nuclear factor kappa-B (NF-κB) pathway

This study aimed to explore the effects of plumbagin on rheumatoid arthritis (RA) and its mechanism. The RA cell model was simulated following the treatment of interleukin-1β (IL-1β). After the treatment of various concentrations of plumbagin, the impact of plumbagin on the cell viability was examined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The collagen-induced arthritis (CIA) model was established using the solution of bovine type II collagen. Hematoxylin-eosin staining was used to observe the changes of ankle joint tissue, while enzyme-linked immunosorbent assay and western blot were applied to detect the level of inflammatory cytokines. Plumbagin inhibited the viability of human fibroblast-like synoviocytes (HFLS) at the concentration of 1 ~ 3.5 μM. The inhibitory effect of 1 μM plumbagin on cell proliferation was similar to that of methotrexate, the drug used as the positive control. Plumbagin downregulated the levels of inflammatory cytokines and matrix metalloproteinases (MMPs) in IL-1β-treated HFLS, and suppressed the activation of IκB and nuclear factor kappa-B (NF-κB) as well as the entry of p65 into the nucleus. It was also demonstrated in animal experiments that plumbagin inhibited the activation of NF-κB pathway, down-regulated the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and MMPs, and alleviated joint damage in CIA-modeled mice. Collectively speaking, plumbagin might down-regulate the levels of inflammatory cytokines and MMPs through inhibiting the activation of the NF-κB pathway, thereby attenuating RA-induced damage to cells and joints.

Abbreviations: CIA: Collagen-induced arthritis; ELISA: Enzyme-linked immuno sorbent assay; HFLS: Human fibroblast-like synoviocytes; IL-6: Interleukin-6; IL-1β: Interleukin-1β; NF-κB: nuclear factor kappa-B; MTT: 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; MMPs: Matrix metalloproteinase; OD: Optical density; RA: Rheumatoid arthritis; SDS: Sodium dodecyl sulfate; SD: Standard deviation; TNF-α: Tumor necrosis factor-α; PVDF: Polyvinylidene fluoride.

Manifestaciones pulmonares de la artritis reumatoide, una revisión en tiempos de pandemia por SARS-CoV-2

La artritis reumatoide (AR) es una de las patologías crónicas de origen autoinmune más frecuentes. Su prevalencia varía del 0,5 al 1%, con un compromiso primario a nivel articular, generando gran discapacidad por las deformidades secundarias derivadas de un estado inflamatorio persistente. Considerando el alto impacto en la calidad de vida de quienes la padecen, sumado al alto costo de las intervenciones terapéuticas, se vuelve imperativo para el personal de salud sumar todos los esfuerzos para promover un diagnóstico temprano y reconocer las potenciales complicaciones con el fin de impactar positivamente en los desenlaces clínicos. Alrededor del 50% de los pacientes con AR pueden tener compromiso extraarticular, siendo el pulmón uno de los órganos más afectados. En época de pandemia por el virus SARS-CoV-2 es necesario recordar los tipos de compromiso pulmonar en pacientes con AR y tener en cuenta la susceptibilidad de estos pacientes a cuadros infecciosos que pueden generar una gran morbimortalidad.

Observational studies: Ambient air pollution and hospitalization for RA-ILD in a heavily polluted city in China

Little is known within the medical community about the impact of air pollution on hospital admissions due to rheumatoid arthritis associated with interstitial lung disease (RA-ILD). Our research aimed to explore whether there is a correlation and to estimate how the association was distributed across various lags in Jinan, China.The relationships between ambient air pollutant concentrations, including PM2.5, PM10, sulfur dioxide (SO2), ozone (O3), and nitrogen dioxide (NO2), and monthly hospitalizations for RA-ILD were studied by employing a general linear model with a Poisson distribution. This time-series study was performed from January 1st, 2015 to December 31st, 2019.In the 5-year study, there were 221 hospitalizations for RA-ILD in Jinan city. The levels of PM2.5, PM10, SO2, and NO2 were significantly related to the number of admissions for RA-ILD. PM2.5, PM10, and SO2 showed the most significant effect on the month (lag 0), and NO2 was most related to RA-ILD at a lag of two months (lag 2). The monthly admissions of RA-ILD increased by 0.875% (95% CI: 0.375-1.377%), 0.548% (95% CI: 0.148-0.949%), 1.968% (95% CI: 0.869-3.080%), and 1.534% (95% CI: 0.305-2.778%) for each 10 μg/m3 increase in PM2.5, PM10, SO2 and NO2, respectively.This study might add more detailed evidence that higher levels of PM2.5, PM10, SO2 and NO2 increase the risk of hospitalizations for RA-ILD. Further study of the role of air pollution in the pathogenesis of RA-ILD is warranted.

Thoracic Involvement in Systemic Autoimmune Rheumatic Diseases: Pathogenesis and Management

Thoracic involvement is one of the main determinants of morbidity and mortality in patients with autoimmune rheumatic diseases (ARDs), with different prevalence and manifestations according to the underlying disease. Interstitial lung disease (ILD) is the most common pulmonary complication, particularly in patients with systemic sclerosis (SSc), idiopathic inflammatory myopathies (IIMs) and rheumatoid arthritis (RA). Other thoracic manifestations include pulmonary arterial hypertension (PAH), mostly in patients with SSc, airway disease, mainly in RA, and pleural involvement, which is common in systemic lupus erythematosus and RA, but rare in other ARDs.In this review, we summarize and critically discuss the current knowledge on thoracic involvement in ARDs, with emphasis on disease pathogenesis and management. Immunosuppression is the mainstay of therapy, particularly for ARDs-ILD, but it should be reserved to patients with clinically significant disease or at risk of progressive disease. Therefore, a thorough, multidisciplinary assessment to determine disease activity and degree of impairment is required to optimize patient management. Nevertheless, the management of thoracic involvement-particularly ILD-is challenging due to the heterogeneity of disease pathogenesis, the variety of patterns of interstitial pneumonia and the paucity of randomized controlled clinical trials of pharmacological intervention. Further studies are needed to better understand the pathogenesis of these conditions, which in turn is instrumental to the development of more efficacious therapies.

Consensus recommendations on managing the selected comorbidities including cardiovascular disease, osteoporosis, and interstitial lung disease in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA)-related comorbidities, including cardiovascular disease (CVD), osteoporosis (OP), and interstitial lung disease (ILD), are sub-optimally managed. RA-related comorbidities affect disease control and lead to impairment in quality of life. We aimed to develop consensus recommendations for managing RA-related comorbidities.

METHODS

The consensus statements were formulated based on emerging evidence during a face-to-face meeting of Taiwan rheumatology experts and modified through three-round Delphi exercises. The quality of evidence and strength of recommendation of each statement were graded after a literature review, followed by voting for agreement. Through a review of English-language literature, we focused on the existing evidence of management of RA-related comorbidities.

RESULTS

Based on experts' consensus, eleven recommendations were developed. CVD risk should be assessed in patients at RA diagnosis, once every 5 years, and at changes in DMARDs therapy. Considering the detrimental effects of nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids on CVD risks, we recommend using the lowest possible dose of corticosteroids and prescribing NSAIDs cautiously. The OP/fragility fracture risk assessment includes dual-energy X-ray absorptiometry and fracture risk assessment (FRAX) in RA. The FRAX-based approach with intervention threshold is a useful strategy for managing OP. RA-ILD assessment includes risk factors, pulmonary function tests, HRCT imaging and a multidisciplinary decision approach to determine RA-ILD severity. A treat-to-target strategy would limit RA-related comorbidities.

CONCLUSIONS

These consensus statements emphasize that adequate control of disease activity and the risk factors are needed for managing RA-related comorbidities, and may provide useful recommendations for rheumatologists on managing RA-related comorbidities.

Validation of an algorithm to identify incident interstitial lung disease in patients with rheumatoid arthritis

Background/purpose

Interstitial lung disease (ILD) is an important problem for patients with rheumatoid arthritis (RA). However, current approaches to ILD case finding in real-world data have been evaluated only in limited settings and identify only prevalent ILD and not new-onset disease. Our objective was to develop, refine, and validate a claims-based algorithm to identify both prevalent and incident ILD in RA patients compared to the gold standard of medical record review.

Methods

We used administrative claims data 2006–2015 from Medicare to derive a cohort of RA patients. We then identified suspected ILD using variations of ILD algorithms to classify both prevalent and incident ILD based on features of the data that included hospitalization vs. outpatient setting, physician specialty, pulmonary-related diagnosis codes, and exclusions for potentially mimicking pulmonary conditions. Positive predictive values (PPV) of several ILD algorithm variants for both prevalent and incident ILD were evaluated.

Results

We identified 234 linkable RA patients with sufficient data to evaluate for ILD. Overall, 108 (46.2%) of suspected cases were confirmed as ILD. Most cases (64%) were diagnosed in the outpatient setting. The best performing algorithm for prevalent ILD had a PPV of 77% (95% CI 67–84%) and for incident ILD was 96% (95% CI 85–100%).

Conclusion

Case finding in administrative data for both prevalent and incident interstitial lung disease in RA patients is feasible and has reasonable accuracy to support population-based research and real-world evidence generation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02655-z.

IL-22 inhibits bleomycin-induced pulmonary fibrosis in association with inhibition of IL-17A in mice

BACKGROUND

Interstitial lung disease, a common extra-articular complication of connective tissue disease, is characterized by progressive and irreversible pulmonary inflammation and fibrosis, which causes significant mortality. IL-22 shows a potential in regulating chronic inflammation and possibly plays an anti-fibrotic role by protecting epithelial cells. However, the detailed effects and underlying mechanisms are still unclear. In this study, we explored the impact of IL-22 on pulmonary fibrosis both in vivo and in vitro.

METHODS

To induce pulmonary fibrosis, wild-type mice and IL-22 knockout mice were intratracheally injected with bleomycin followed by treatments with recombinant IL-22 or IL-17A neutralizing antibody. We investigated the role of IL-22 on bleomycin-induced pulmonary fibrosis and the mechanism in the possible interaction between IL-22 and IL-17A. Fibrosis-related genes were detected using RT-qPCR, western blot, and immunofluorescence. Inflammatory and fibrotic changes were assessed based on histological features. We also used A549 human alveolar epithelial cells, NIH/3T3 mouse fibroblast cells, and primary mouse lung fibroblasts to study the impact of IL-22 on fibrosis in vitro.

RESULTS

IL-22 knockout mice showed aggravated pulmonary fibrosis compared with wild-type mice, and injection of recombinant IL-22 decreased the severe fibrotic manifestations in IL-22 knockout mice. In cell culture assays, IL-22 decreased protein levels of Collagen I in A549 cells, NIH/3T3 cells, and primary mouse lung fibroblasts. IL-22 also reduced the protein level of Collagen I in NIH/3T3 cells which were co-cultured with T cells. Mechanistically, IL-22 reduced the Th17 cell proportion and IL-17A mRNA level in lung tissues, and treatment with an IL-17A neutralizing antibody alleviated the severe pulmonary fibrosis in IL-22 knockout mice. The IL-17A neutralizing antibody also reduced Collagen I expression in NIH/3T3 cells in vitro. Knockdown of IL-17A with siRNAs or administration of IL-22 in NIH/3T3 cells and MLFs decreased expression of Collagen I, an effect blocked by concurrent use of recombinant IL-17A.

CONCLUSIONS

IL-22 mediated an anti-fibrogenesis effect in the bleomycin-induced pulmonary fibrosis model and this effect was associated with inhibition of IL-17A.

Baricitinib and the Risk of Incident Interstitial Lung Disease: A Descriptive Clinical Case Report from Clinical Trials

OBJECTIVES

Interstitial lung disease (ILD) occurs in up to 30% of patients with rheumatoid arthritis (RA), resulting in increased morbidity and death in the absence of proven therapies. The aim of this study is to estimate the number of incident ILD cases reported through development studies with baricitinib in patients with RA.

METHODS

Estimates were based on 3770 patients with RA from eight randomized clinical trials (four phase 3, three phase 2, one phase 1b) and one long-term extension study on baricitinib for which ILD was not an exclusion criterion with 12,358 patient-years of exposure (PYE).

RESULTS

Twenty-one non-infectious cases of ILD were reported with an exposure-adjusted incidence rate (EAIR) of 0.17 per 100 PYE. Of the 21 cases, six were reported as serious and 15 as non-serious resulting in an incidence rate of 0.05 per 100 PYE and 0.12 per 100 PYE, respectively. There were also 11 cases caused by an infectious agent: seven serious (IR: 0.06 per 100 PYE) and four non-serious cases (IR: 0.03 per 100 PYE).

CONCLUSIONS

The findings of this analysis in patients with RA treated with baricitinib are consistent with a low risk to develop non-infectious ILD during baricitinib treatment, similar to that observed with other Janus kinase inhibitors.

Rheumatoid arthritis related interstitial lung disease

INTRODUCTION

Interstitial lung disease (ILD) represents a frequent extra-articular manifestation of rheumatoid arthritis (RA) deeply impacting both quality of life and overall prognosis. Areas covered: A literature search was performed including PubMed, Embase, Scopus, and Web of Science. Many retrospective studies investigated the possible risk factors for RA-related ILD (RA-ILD), aiming to identify patients at risk. Among them, males, smokers, positivity of anti-citrullinated peptide antibodies have been associated with RA-ILD, such as some genetic haplotypes. Usual interstitial pneumonia is the histologic and radiologic pattern most frequently observed, followed by nonspecific interstitial pneumonia. Since lung involvement can represent the RA onset, an early differential diagnosis with idiopathic interstitial pneumonia can be difficult or sometimes impossible. High-resolution computed tomography represents the gold standard for ILD diagnosis, while multidisciplinary discussion should be required to assess disease staging, severity and progression.  Expert opinion: Management of RA-ILD patients is challenging due to the lack of evidence-based data regarding both assessment and treatment. Moreover, the high variability of clinical presentation and evolution makes it difficult to establish the correct therapeutic strategy. Currently, multidisciplinary approach, including at least rheumatologists, pulmonologists, and radiologists, is desirable to define therapy and follow-up strategies.

Regulatory Immune Cells in Idiopathic Pulmonary Fibrosis: Friends or Foes?

The immune system is receiving increasing attention for interstitial lung diseases, as knowledge on its role in fibrosis development and response to therapies is expanding. Uncontrolled immune responses and unbalanced injury-inflammation-repair processes drive the initiation and progression of idiopathic pulmonary fibrosis. The regulatory immune system plays important roles in controlling pathogenic immune responses, regulating inflammation and modulating the transition of inflammation to fibrosis. This review aims to summarize and critically discuss the current knowledge on the potential role of regulatory immune cells, including mesenchymal stromal/stem cells, regulatory T cells, regulatory B cells, macrophages, dendritic cells and myeloid-derived suppressor cells in idiopathic pulmonary fibrosis. Furthermore, we review the emerging role of regulatory immune cells in anti-fibrotic therapy and lung transplantation. A comprehensive understanding of immune regulation could pave the way towards new therapeutic or preventive approaches in idiopathic pulmonary fibrosis.

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.

Efficacy and safety of mycophenolate mofetil in the treatment of rheumatic disease-related interstitial lung disease: a narrative review

Mycophenolate mofetil (MMF) is an antimetabolite with a potent inhibitory effect on proliferation of T and B lymphocytes used since the early 1990s for the prevention of acute allograft rejection after organ transplant. MMF is also widely used for the treatment of a variety of rheumatic diseases (RDs) and their pulmonary involvement. Interstitial lung disease (ILD) is a heterogeneous group of progressive fibrotic diseases of the lung, which is often secondary to RD and represents a major cause of morbidity and mortality. MMF is considered the main alternative to cyclophosphamide as a first-line agent to treat RD-related ILD or as possible maintenance therapy after cyclophosphamide, with a lower rate of side-effects. However, as for other immunosuppressive agents, the use of MMF in RD-ILD is supported by poor scientific evidence. In this narrative review, we describe the available data and recent advances on the effectiveness and safety of MMF for the treatment of ILD related to RD, including rheumatoid arthritis, systemic sclerosis, primary Sjögren syndrome, systemic lupus erythematosus, idiopathic inflammatory myopathies, undifferentiated connective tissue disease, interstitial pneumonia with autoimmune features and antineutrophil cytoplasmic antibody-associated vasculitis.

Targeted therapies in interstitial lung disease secondary to systemic autoimmune rheumatic disease. Current status and future development

Autoimmune rheumatic diseases (ARD) are characterized by systemic manifestations and multiple organ involvement, including the lung. Interstitial Lung Disease (ILD) is a cardinal manifestation of lung involvement in patients with ARD and is associated with significant morbidity and mortality. Corticosteroids and immunosuppressive drugs are used as first -line treatment. Targeted therapies, such as biological disease modifying antirheumatic drugs (DMARDS) and anti- fibrotic agents are new treatment options. In this review we discuss the role of targeted therapies in patients with ILD secondary to ARD.

CXCL9, CXCL10, and CXCL11; biomarkers of pulmonary inflammation associated with autoimmunity in patients with collagen vascular diseases-associated interstitial lung disease and interstitial pneumonia with autoimmune features

Introduction

Interstitial lung disease (ILD) is a heterogeneous group of diseases characterized by varying degrees of lung inflammation and/or fibrosis. We investigated biomarkers to infer whether patients with collagen vascular diseases associated ILD (CVD–ILD) and interstitial pneumonia with autoimmune features (IPAF) benefit from immunosuppressive therapy.

Materials and methods

We retrospectively investigated patients with CVD–ILD, IPAF, and idiopathic pulmonary fibrosis (IPF) between June 2013 and May 2017 at our department. First, we assessed differences in serum and bronchoalveolar lavage fluid (BALF) levels of cytokines between groups. Second, we assessed the associations of patient’s clinical variables with serum and BALF levels of those cytokines that were different between groups. Finally, we assessed the associations of diagnosis and response to immunosuppressive therapy with serum levels of those cytokines that were different between groups.

Results

We included 102 patients (51 with IPF, 35 with IPAF, and 16 with CVD–ILD). Serum and BALF levels of CXCL9, CXCL10, and CXCL11 were significantly elevated in patients with IPAF or CVD–ILD compared with those in patients with IPF. BALF levels of CXCL9 and CXCL10 were correlated with the percentages of lymphocytes and macrophages in BALF. Serum levels of CXCL9 and CXCL10 were correlated with BALF levels. Serum levels of CXCL9, CXCL10, and CXCL11 were correlated C-reactive protein, percent predicted forced vital capacity, alveolar-arterial oxygen difference, and the percentages of lymphocytes and macrophages in BALF. Serum levels of CXCL9, CXCL10, and CXCL11 showed moderate accuracy to distinguish patients with CVD–ILD from those with IPAF and IPF. Pre-treatment serum levels of CXCL9 and CXCL11 showed strong positive correlations with the annual forced vital capacity changes in patients with IPAF and CVD–ILD treated with immunosuppressive drugs.

Conclusions

Serum CXCL9, CXCL10, and CXCL11 are potential biomarkers for autoimmune inflammation and predictors of the immunosuppressive therapy responses in ILD with background autoimmunity.

A Case of Rheumatoid Arthritis-Associated Interstitial Lung Disease - An Unfortunate Complication of Untreated Rheumatoid Arthritis!

Rheumatoid arthritis-associated interstitial lung disease (RA-ILD) is a rare extraarticular manifestation of the systemic autoimmune disease rheumatoid arthritis. RA-ILD is one of the leading causes of morbidity and mortality in patients with rheumatoid arthritis. It is more commonly seen in patients with risk factors, which include male sex, severe rheumatoid arthritis, and smoking. The presentation depends on the extent of the underlying pathology. Patients can remain asymptomatic for extended periods of time and progressively develop symptoms such as shortness of breath on exertion and a nonproductive cough. The diagnosis is made using a combination of clinical presentation, pulmonary function testing, and imaging. It is difficult for a practitioner to distinguish the presentation of interstitial lung disease from other causes and RA-ILD. However, it is extremely important to differentiate them due to the differences in management. The treatment usually involves a multidisciplinary team guided approach towards treating the underlying rheumatoid arthritis. Asymptomatic patients are managed by observation, while symptomatic patients are managed with glucocorticoids and immunosuppressants. Accurate and early treatment can lead to an improvement in a patient's symptoms and significantly improve their quality of life. We present an interesting case of a female with a long-standing history of rheumatoid arthritis not on any treatment presenting to the ED with exertional shortness of breath, dry cough, and abdominal distension.

Microbial Influences of Mucosal Immunity in Rheumatoid Arthritis

PURPOSE OF REVIEW

This review will summarize recent data defining the relationship between rheumatoid arthritis (RA) and the microbiome at mucosal sites throughout the body. It will highlight what is known, what is speculated, and current knowledge gaps regarding the microbiome in RA.

RECENT FINDINGS

An extensive relationship between the microbiome and immune cell function can influence RA-related inflammation and T cell and B cell biology. Studies are beginning to characterize microbial changes in individuals who are at risk for RA, which is a critical element needed to understand the influence of the microbiome on RA pathogenesis. Expanding our understanding of the microbiome in RA beyond the bacteria at the gut and oral mucosae into the lung and urogenital surfaces, including viral and fungal components, and establishing the relationship across mucosal sites will be critical in future work. Importantly, approaches to manipulate the microbiome could lead to novel therapeutic and preventive strategies.

Pathogenesis and treatment of idiopathic and rheumatoid arthritis-related interstitial pneumonia. The possible lesson from COVID-19 pneumonia

INTRODUCTION

Main clinical manifestations of SARS-CoV-2 infection are characterized by fever, dyspnea, and interstitial pneumonia, frequently evolving in acute respiratory distress syndrome (ARDS).

AREAS COVERED

Features of coronavirus disease 2019 (COVID-19) presents some common points with interstitial lung disease (ILD) both idiopathic and related to rheumatoid arthritis (RA), typically characterized by a chronic progression over time and possibly complicated by acute exacerbation (AE). The study of common pathogenetic mechanisms, such as the involvement of toll-like receptor 4, could contribute to the knowledge and treatment of idiopathic and RA-ILD. Moreover, hyperinflammation, mainly characterized by increase of effector T-cells and inflammatory cytokines, and activation of coagulation cascade, observed in COVID-19 related ARDS have been already shown in patients with AE of idiopathic and RA-ILD. A literature search was performed in PubMed, Embase, Scopus, and Web of Science, together with a manual search in COVID-resource centers of the main journals.

EXPERT OPINION

Despite the uncertainty about pathogenetic aspects about COVID-19- pneumonia, it could be a possible model for other forms of ILD and AE. The great amount of data from studies on COVID-19 could be helpful in proposing safe therapeutic approaches for RA-ILD, in understanding pathogenesis of usual interstitial pneumonia and to develop new therapeutic strategies for AE.

Treatment of Rheumatoid Arthritis-Associated Interstitial Lung Disease: Lights and Shadows

Rheumatoid arthritis (RA) is a chronic and systemic inflammatory disease affecting 0.5–1% of the population worldwide. Interstitial lung disease (ILD) is a serious pulmonary complication of RA and it is responsible for 10–20% of mortality, with a mean survival of 5–8 years. However, nowadays there are no therapeutic recommendations for the treatment of RA-ILD. Therapeutic options for RA-ILD are complicated by the possible pulmonary toxicity of many disease modifying anti-rheumatic drugs (DMARDs) and by their unclear efficacy on pulmonary disease. Therefore, joint and lung involvement should be evaluated independently of each other for treatment purposes. On the other hand, some similarities between RA-ILD and idiopathic pulmonary fibrosis and the results of the recent INBIULD trial suggest a possible future role for antifibrotic agents. From this perspective, we review the current literature describing the pulmonary effects of drugs (immunosuppressants, conventional, biological and target synthetic DMARDs and antifibrotic agents) in patients with RA and ILD. In addition, we suggest a framework for the management of RA-ILD patients and outline a research agenda to fill the gaps in knowledge about this challenging patient cohort.

Connective Tissue Disease-Associated Interstitial Lung Disease: Evaluation and Management

Interstitial lung disease is common among patients with connective tissue disease and is an important contributor to morbidity and mortality. Infection and drug toxicity must always be excluded as the cause of radiographic findings. Immunosuppression remains a mainstay of therapy despite few controlled trials supporting its use. When a decision regarding therapy initiation is made, considerations include an assessment of disease severity as well as a determination of the rate of progression. Because patients may have extrathoracic disease activity, a multidisciplinary approach is crucial and should include supportive and nonpharmacologic management strategies.

Immune checkpoint inhibitor-induced inflammatory arthritis as a model of autoimmune arthritis

The development of inflammatory arthritis in patients receiving immune checkpoint inhibitor therapy is increasingly recognized due to the growing use of these drugs for the treatment of cancer. This represents an important opportunity not only to define the mechanisms responsible for the development of this immune-related adverse event and to ultimately predict or prevent its development, but also to provide a unique window into early events in the development of inflammatory arthritis. Knowledge gained through the study of this patient population, for which the inciting event is known, could shed light into the pathogenesis of autoimmune arthritis. This review will highlight the clinical and immunologic features of these entities to define common elements for future study.

18F-AzaFol for Detection of Folate Receptor-β Positive Macrophages in Experimental Interstitial Lung Disease-A Proof-of-Concept Study

Background: Interstitial lung disease (ILD) is a common and severe complication in rheumatic diseases. Folate receptor-β is expressed on activated, but not resting macrophages which play a key role in dysregulated tissue repair including ILD. We therefore aimed to pre-clinically evaluate the potential of 18F-AzaFol-based PET/CT (positron emission computed tomography/computed tomography) for the specific detection of macrophage-driven pathophysiologic processes in experimental ILD. Methods: The pulmonary expression of folate receptor-β was analyzed in patients with different subtypes of ILD as well as in bleomycin (BLM)-treated mice and respective controls using immunohistochemistry. PET/CT was performed at days 3, 7, and 14 after BLM instillation using the 18F-based folate radiotracer 18F-AzaFol. The specific pulmonary accumulation of the radiotracer was assessed by ex vivo PET/CT scans and quantified by ex vivo biodistribution studies. Results: Folate receptor-β expression was 3- to 4-fold increased in patients with fibrotic ILD, including idiopathic pulmonary fibrosis and connective tissue disease-related ILD, and significantly correlated with the degree of lung remodeling. A similar increase in the expression of folate receptor-β was observed in experimental lung fibrosis, where it also correlated with disease extent. In the mouse model of BLM-induced ILD, pulmonary accumulation of 18F-AzaFol reflected macrophage-related disease development with good correlation of folate receptor-β positivity with radiotracer uptake. In the ex vivo imaging and biodistribution studies, the maximum lung accumulation was observed at day 7 with a mean accumulation of 1.01 ± 0.30% injected activity/lung in BLM-treated vs. control animals (0.31 ± 0.06% % injected activity/lung; p < 0.01). Conclusion: Our preclinical proof-of-concept study demonstrated the potential of 18F-AzaFol as a novel imaging tool for the visualization of macrophage-driven fibrotic lung diseases.

New treatment paradigms for connective tissue disease-associated interstitial lung disease

PURPOSE OF REVIEW

Interstitial lung disease (ILD) is frequently observed in connective tissue disease (CTD) and is a major cause of mortality. In CTD-ILD, a marked variability in morphological patterns, time course and severity exists. In many patients, CTD-ILD is limited and inherently stable, although a significant proportion of patients have progressive disease. We review the utility of integration of the recently proposed disease behavior classification into the management of CTD-ILD, and recent advances in treatment approaches.

RECENT FINDINGS

Recent studies on scleroderma-ILD (SSc-ILD) staging and short-term lung function trends provide important information, although accurate prognostic markers, particularly in limited/early CTD-ILD, are still needed. Most patients with progressive CTD-ILD stabilize on immunosuppression, as observed in recent SSc-ILD trials and CTD-ILD retrospective series. A minority of patients present with life-threatening acute/subacute ILD, requiring intense immunosuppression, with limited available guidance. A significant minority of CTD-ILD patients have progressive disease despite immunosuppression. Ongoing trials with antifibrotic agents and with biologic agents may reveal a potential role for their use/addition.

SUMMARY

Ultimately, further research into the mechanisms linking autoimmunity to fibrosis and randomized controlled clinical trials are needed, with the aim of preventing irreversible damage of lung tissue, while minimizing burden of treatment.

Diagnostic accuracy of anti-keratin antibody for rheumatoid arthritis: a meta-analysis

OBJECTIVES

Anti-keratin antibody (AKA) is a serum antibody for patients with rheumatoid arthritis (RA), and it has a high specificity. Diagnostic role of AKA in RA was evaluated in this study.

METHODS

PubMed, EMBASE, and Web of Science were searched to acquire eligible studies. Articles published before 15 March 2018 were considered to be included. Quality Assessment of Diagnostic Accuracy Studies 2 was used to evaluate the risk of bias and application concern of the included articles. Pooled analysis of diagnostic indicators of AKA for RA was conducted by using a random effects model. Subgroup analysis was employed to explore the potential influencing factors. RevMan 5.3, Stata 11.0, and Meta-DiSc 1.4 software were used in this study.

RESULTS

A total of 15 studies (2350 positive and 2067 negative participants) were included. The pooled sensitivity was 0.46 (95% CI 0.44-0.48), pooled specificity was 0.94 (95% CI 0.93-0.95), and pooled diagnostic odds ratio was 15.86 (95% CI 9.48-26.52). In addition, the area under the curve was 0.7194.

CONCLUSIONS

The current evidence indicated that AKA has high diagnostic specificity in RA and may be useful for RA diagnostic application in clinic.

Molecular Modeling Studies on Carbazole Carboxamide Based BTK Inhibitors Using Docking and Structure-Based 3D-QSAR

Rheumatoid arthritis (RA) is the second common rheumatic immune disease with chronic, invasive inflammatory characteristics. Non-steroidal anti-inflammatory drugs (NSAIDs), slow-acting anti-rheumatic drugs (SAARDs), or glucocorticoid drugs can improve RA patients’ symptoms, but fail to cure. Broton’s tyrosine kinase (BTK) inhibitors have been proven to be an efficacious target against autoimmune indications and B-cell malignancies. Among the current 11 clinical drugs, only BMS-986142, classified as a carbazole derivative, is used for treating RA. To design novel and highly potent carbazole inhibitors, molecular docking and three dimensional quantitative structure–activity relationship (3D-QSAR) were applied to explore a dataset of 132 new carbazole carboxamide derivatives. The established comparative molecular field analysis (CoMFA) (q² = 0.761, r² = 0.933) and comparative molecular similarity indices analysis (CoMSIA) (q² = 0.891, r² = 0.988) models obtained high predictive and satisfactory values. CoMFA/CoMSIA contour maps demonstrated that bulky substitutions and hydrogen-bond donors were preferred at R₁ and 1-position, respectively, and introducing hydrophilic substitutions at R₁ and R₄ was important for improving BTK inhibitory activities. These results will contribute to the design of novel and highly potent BTK inhibitors.