Review: interstitial lung disease associated with systemic sclerosis and idiopathic pulmonary fibrosis: how similar and distinct?

Explainable fully automated CT scoring of interstitial lung disease for patients suspected of systemic sclerosis by cascaded regression neural networks and its comparison with experts

Visual scoring of interstitial lung disease in systemic sclerosis (SSc-ILD) from CT scans is laborious, subjective and time-consuming. This study aims to develop a deep learning framework to automate SSc-ILD scoring. The automated framework is a cascade of two neural networks. The first network selects the craniocaudal positions of the five scoring levels. Subsequently, for each level, the second network estimates the ratio of three patterns to the total lung area: the total extent of disease (TOT), ground glass (GG) and reticulation (RET). To overcome the score imbalance in the second network, we propose a method to augment the training dataset with synthetic data. To explain the network's output, a heat map method is introduced to highlight the candidate interstitial lung disease regions. The explainability of heat maps was evaluated by two human experts and a quantitative method that uses the heat map to produce the score. The results show that our framework achieved a κ of 0.66, 0.58, and 0.65, for the TOT, GG and RET scoring, respectively. Both experts agreed with the heat maps in 91%, 90% and 80% of cases, respectively. Therefore, it is feasible to develop a framework for automated SSc-ILD scoring, which performs competitively with human experts and provides high-quality explanations using heat maps. Confirming the model's generalizability is needed in future studies.

Parvovirus B19 in Rheumatic Diseases

Parvovirus B19 (B19V) is a human pathogen belonging to the Parvoviridae family. It is widely diffused in the population and responsible for a wide range of diseases, diverse in pathogenetic mechanisms, clinical course, and severity. B19V infects and replicates in erythroid progenitor cells (EPCs) in the bone marrow leading to their apoptosis. Moreover, it can also infect, in an abortive manner, a wide set of different cell types, normally non-permissive, and modify their normal physiology. Differences in the characteristics of virus-cell interaction may translate into different pathogenetic mechanisms and clinical outcomes. Joint involvement is a typical manifestation of B19V infection in adults. Moreover, several reports suggest, that B19V could be involved in the pathogenesis of some autoimmune rheumatologic diseases such as rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), systemic sclerosis (SSc), systemic lupus erythematosus (SLE), or vasculitis. This review provides basic information on the B19 virus, highlights characteristics of viral infection in permissive and non-permissive systems, and focuses on recent findings concerning the pathogenic role of B19V in rheumatologic diseases.

cGAS Expression is Enhanced in Systemic Sclerosis Associated Interstitial Lung Disease and Stimulates Inflammatory Myofibroblast Activation

Objective

The lungs of patients with Systemic Sclerosis Associated Interstitial Lung Disease (SSc-ILD) contain inflammatory myofibroblasts arising in association with fibrotic stimuli and perturbed innate immunity. The innate immune DNA binding receptor Cyclic GMP-AMP synthase (cGAS) is implicated in inflammation and fibrosis, but its involvement in SSc-ILD remains unknown. We examined cGAS expression, activity, and therapeutic potential in SSc-ILD using cultured fibroblasts, precision cut lung slices (PCLS), and a well-accepted animal model.

Methods

Expression and localization of cGAS, cytokines, and type 1 interferons were evaluated in SSc-ILD lung tissues, bronchoalveolar lavage (BAL), and isolated lung fibroblasts. CGAS activation was assessed in a publicly available SSc-ILD single cell RNA sequencing dataset. Production of cytokines, type 1 interferons, and αSMA elicited by TGFβ1 or local substrate stiffness were measured in normal human lung fibroblasts (NHLFs) via qRT-PCR, ELISA, and immunofluorescence. Small molecule cGAS inhibition was tested in cultured fibroblasts, human PCLS, and the bleomycin pulmonary fibrosis model.

Results

SSc-ILD lung tissue and BAL are enriched for cGAS, cytokines, and type 1 interferons. The cGAS pathway shows constitutive activation in SSc-ILD fibroblasts and is inducible in NHLFs by TGFβ1 or mechanical stimuli. In these settings, and in human PCLS, cGAS expression is paralleled by the production of cytokines, type 1 interferons, and αSMA that are mitigated by a small molecule cGAS inhibitor. These findings are recapitulated in the bleomycin mouse model.

Conclusion

cGAS signaling contributes to pathogenic inflammatory myofibroblast phenotypes in SSc-ILD. Inhibiting cGAS or its downstream effectors represents a novel therapeutic approach.

Research Progress in pathogenesis of connective tissue disease-associated interstitial lung disease from the perspective of pulmonary cells

The lungs are a principal factor in the increased morbidity and mortality observed in patients with Connective Tissue Disease (CTD), frequently presenting as CTD-associated Interstitial Lung Disease (ILD). Currently, there is a lack of comprehensive descriptions of the pulmonary cells implicated in the development of CTD-ILD. This review leverages the Human Lung Cell Atlas (HLCA) and spatial multi-omics atlases to discuss the advancements in research on the pathogenesis of CTD-ILD from a pulmonary cell perspective. This facilitates a more precise localization of disease sites and a more systematic consideration of disease progression, supporting further mechanistic studies and targeted therapies.

Macrophages as determinants and regulators of systemic sclerosis-related interstitial lung disease

BACKGROUND

Interstitial lung disease (ILD) is the primary cause of mortality in systemic sclerosis (SSc), an autoimmune disease characterized by tissue fibrosis. SSc-related ILD (SSc-ILD) occurs more frequently in females aged 30-55 years, whereas idiopathic pulmonary fibrosis (IPF) is more prevalent in males aged 60-75 years. SSc-ILD occurs earlier than IPF and progresses rapidly. FCN1, FABP4, and SPP1 macrophages are involved in the pathogenesis of lung fibrosis; SPP1 macrophages demonstrate upregulated expression in both SSc-ILD and IPF. To identify the differences between SSc-ILD and IPF using single-cell analysis, clarify their distinct pathogeneses, and propose directions for prevention and treatment.

METHODS

We performed single-cell RNA sequencing on NCBI Gene Expression Omnibus (GEO) databases GSE159354 and GSE212109, and analyzed lung tissue samples across healthy controls, IPF, and SSc-ILD. The primary measures were the filtered genes integrated with batch correction and annotated cell types for distinguishing patients with SSc-ILD from healthy controls. We proposed an SSc-ILD pathogenesis using cell-cell interaction inferences, and predicted transcription factors regulating target genes using SCENIC. Drug target prediction of the TF gene was performed using Drug Bank Online.

RESULTS

A subset of macrophages activates the MAPK signaling pathway under oxidative stress. Owing to the lack of inhibitory feedback from ANNEXIN and the autoimmune characteristics, this leads to an earlier onset of lung fibrosis compared to IPF. During initial lung injury, fibroblasts begin to activate the IL6 pathway under the influence of SPP1 alveolar macrophages, but IL6 appears unrelated to other inflammatory and immune cells. This may explain why tocilizumab (an anti-IL6-receptor antibody) only preserves lung function in patients with early SSc-ILD. Finally, we identified BCLAF1 and NFE2L2 as influencers of MAPK activation in macrophages. Metformin downregulates NFE2L2 and could serve as a repurposed drug candidate.

CONCLUSIONS

SPP1 alveolar macrophages play a role in the profibrotic activity of IPF and SSc-ILD. However, SSc-ILD is influenced by autoimmunity and oxidative stress, leading to the continuous activation of MAPK in macrophages. This may result in an earlier onset of lung fibrosis than in IPF. Such differences could serve as potential research directions for early prevention and treatment.

Sirtuins and Cellular Senescence in Patients with Idiopathic Pulmonary Fibrosis and Systemic Autoimmune Disorders

The sirtuin family is a heterogeneous group of proteins that play a critical role in many cellular activities. Several degenerative diseases have recently been linked to aberrant sirtuin expression and activity because of the involvement of sirtuins in maintaining cell longevity and their putative antiaging function. Idiopathic pulmonary fibrosis and progressive pulmonary fibrosis associated with systemic autoimmune disorders are severe diseases characterized by premature and accelerated exhaustion and failure of alveolar type II cells combined with aberrant activation of fibroblast proliferative pathways leading to dramatic destruction of lung architecture. The mechanisms underlying alveolar type II cell exhaustion in these disorders are not fully understood. In this review, we have focused on the role of sirtuins in the pathogenesis of idiopathic and secondary pulmonary fibrosis and their potential as biomarkers in the diagnosis and management of fibrotic interstitial lung diseases.

Serum netrin-1 levels are high in Rheumatoid arthritis associated interstitial lung disease

BACKGROUND

Recent data show that netrin-1 has a role in development of pulmonary fibrosis. This study was aimed to investigate serum netrin-1 level and its relation to interstitial lung disease(ILD) in patients with rheumatoid arthritis (RA).

METHOD

42 RA patients with RA-ILD, 58 RA patients without RA-ILD (RA non-ILD group), and 61 healthy volunteers were included in this study. The modified DAS28-ESR score was used to calculate disease activity in RA patients. Using the quantitative immunoassay method, Serum netrin-1 levels were measured with an ELISA kit (Catalog number: E-EL-H2328; lab science, lot number: GZWTKZ5SWK, Texas, USA).

RESULTS

The median value of netrin-1 was found to be significantly higher in the RA-ILD group (82.9 [59.9-124]) compared to both the RA non-ILD group(52.9 [49.5-73.1])(B = -0.006, OR = 0.994, CI 95 %=0.989-0.999, P = 0.018) and the control group(53.5 [49.5-87.5]) (B: -0.005, OR: 0.994, CI 95 %: 0.990-0.999, p: 0.022). A cut-off value of 61.78 for netrin-1 was found to have a sensitivity of 73.8 % and a specificity of 69 % for the diagnosis of RA-ILD (AUC [95 %Cl] = 0.771 [0.679-0.862], p < 0.0001).It was found that high serum netrin-1 level was strongly associated with the RA-usual interstitial pneumonia(UIP) pattern and poorly related to the RA-nonspecific interstitial pneumonia(NSIP) pattern compared to the RA non-ILD group.

CONCLUSIONS

Netrin-1 is elevated in the serum of patients with RA-ILD, especially in the UIP pattern. Netrin-1 may be a potential candidate for predicting the development of RA-ILD that should be investigated in the pathophysiological and therapeutic fields..

KL6 and IL-18 levels are negatively correlated with respiratory function tests and ILD extent assessed on HRCT in patients with systemic sclerosis-related interstitial lung disease (SSc-ILD)

BACKGROUND

Interstitial lung disease (ILD) is one of the leading causes of mortality in patients with systemic sclerosis (SSc). Serum biomarkers have been suggested as indicators for pulmonary damage with clinical value in the diagnosis and prognosis of SSc-ILD.

OBJECTIVES

To investigate the role of serum biomarkers (Krebs von den Lungen-6 KL-6, IL-18 and IL-18BP) as a potential biomarker reflecting the severity of SSc-ILD as assessed through high-resolution computed tomography (HRCT) and pulmonary function tests (PFT), including forced vital capacity (%FVC) and diffusing capacity of the lung for carbon monoxide (%DLCO).

METHODS

A cross-sectional study including patients with SSc fulfilling the 2013 ACR/EULAR criteria was performed. Patients were classified according to disease duration and pulmonary involvement (presence of ILD). All SSc patients underwent chest HRCT scans and pulmonary function test at baseline. Serum concentration of KL-6, IL8 and IL18BP were determined using the quantitative ELISA technique, sandwich type (solid phase sandwich Enzyme Linked-Immuno-Sorbent Assay), with kits from MyBiosource for KL-6 and from Invitrogen for IL18 and IL18BP. A semiquantitative grade of ILD extent was evaluated through HRCT scan (grade 1, 0-20%; grade 2, >20%). Extensive disease was defined as >20% lung involvement on HRCT, and FVC <70% predicted and limited lung involvement as ≤20% ILD involvement on HRCT, and an FVC ≥70% predicted.

RESULTS

74 patients were included, 27% were male. The mean age at diagnosis was 57.5±15 years and the mean time since diagnosis was 7.67±8 years. 28 patients had ILD (38%). 64% of patients had <20% ILD extent classified through HRCT scan. SSc-ILD patients had elevated serum KL-6 and IL-18 levels compared to patients without ILD (p=0.003 and p=0.04), and those findings were preserved after adjusting for age and sex. Negative correlation between KL-6 levels and%FVC (β=-0.25, p 0.037) and% DLCO (β=-0.28, p 0.02) and between IL-18 levels and%FVC (β=-0.38, p 0.001) and%DLCO (β=-0.27, p 0.03) were found. Serum KL-6 and IL-18 levels successfully differentiated grades 1 and 2 of the semiquantitative grades of ILD extent (p = 0.028 and p = 0.022). Semiquantitative grades of ILD on the HRCT scan were significantly proportional to the KL-6 (p = 0.01) and IL-18 (p = 0.03). A positive correlation between extensive lung disease and KL-6 (β=0.42, p = 0.007) but not with IL-18 was found.

CONCLUSIONS

Serum KL-6 levels and IL-18 were increased in patients with SSc-ILD and showed a positive correlation with ILD severity as measured using a semiquantitative CT grading scale and negative correlation with PFT parameters. Serum KL-6 and IL-18 could be a clinically useful biomarker in screening and evaluating SSc-ILD.

Neurological, cardiac, musculoskeletal, and renal manifestations of scleroderma along with insights into its genetics, pathophysiology, diagnostic, and therapeutic updates

Background

Scleroderma, also referred to as systemic sclerosis, is a multifaceted autoimmune condition characterized by abnormal fibrosis and impaired vascular function. Pathologically, it encompasses the persistent presence of inflammation, abnormal collagen buildup, and restructuring of blood vessels in various organs, resulting in a wide range of clinical symptoms. This review incorporates the most recent scientific literature on scleroderma, with a particular emphasis on its pathophysiology, clinical manifestations, diagnostic approaches, and treatment options.

Methodology

A comprehensive investigation was carried out on numerous databases, such as PubMed, MEDLINE, Scopus, Web of Science, and Google Scholar, to collect pertinent studies covering diverse facets of scleroderma research.

Results

Scleroderma presents with a range of systemic manifestations, such as interstitial lung disease, gastrointestinal dysmotility, Raynaud's phenomenon, pulmonary arterial hypertension, renal complications, neurological symptoms, and cardiac abnormalities. Serological markers, such as antinuclear antibodies, anti-centromere antibodies, and anti-topoisomerase antibodies, are important for classifying diseases and predicting their outcomes.

Discussion

The precise identification of scleroderma is crucial for promptly and correctly implementing effective treatment plans. Treatment approaches aim to improve symptoms, reduce complications, and slow down the progression of the disease. An integrated approach that combines pharmacological agents, including immunosuppressants, endothelin receptor antagonists, and prostanoids, with nonpharmacological interventions such as physical and occupational therapy is essential for maximizing patient care.

Conclusion

Through the clarification of existing gaps in knowledge and identification of emerging trends, our goal is to improve the accuracy of diagnosis, enhance the effectiveness of therapeutic interventions, and ultimately enhance the overall quality of life for individuals suffering from scleroderma. Ongoing cooperation and creative research are necessary to advance the field and achieve improved patient outcomes and new therapeutic discoveries.

Experiences of systemic sclerosis patients with home monitoring of their pulmonary function: a qualitative study

Objective

To evaluate the experiences, perceived benefits and disadvantages of home monitoring of pulmonary function in SSc patients with interstitial lung disease (ILD).

Methods

Semistructured interviews were conducted among SSc-ILD patients who used the home monitoring application of pulmonary function for at least 3 months. In our program, patients are instructed to perform home spirometry weekly at fixed time points using a mobile application with results being directly visible for patients and physicians. Audiotapes of the interviews were transcribed verbatim and analysed using inductive thematic analysis after performing a member check.

Results

A total of 13 patients were interviewed, with a median age of 58 years (range 36-75) and a median experience with home monitoring of 12 months (range 3-12). We identified four major themes, including routine of telemonitoring, impact of telemonitoring, trust in telemonitoring and implementation in regular healthcare. Overall, patients found performing home spirometry to be feasible. Major perceived benefits of performing home spirometry are an increase in patient empowerment, better understanding of the disease course and a reduction in hospital visits, whereas identified disadvantages are an emotional burden of telemonitoring, heightened awareness of illness, doubts about its validity and the need for digital competencies. All patients expressed their willingness to continue, although some patients emphasized the need for face-to-face visits.

Conclusion

Telemonitoring of pulmonary function is accepted by SSc-ILD patients with the perceived benefits outweighing the disadvantages. Adopting a patient-centred strategy that considers individual factors and addresses concerns proactively is warranted to successfully implement home spirometry.

The Performance of Pulmonary Function Tests in Predicting Systemic Sclerosis-Interstitial Lung Disease in the European Scleroderma Trial and Research Database

BACKGROUND AND OBJECTIVES

In SSc, ILD is a major cause of morbidity and mortality. We aimed to investigate the performance of DLCO (diffusing capacity of lung carbon monoxide) and FVC (forced vital capacity) delta change (Δ) and baseline values in predicting the development of SSc-ILD.

METHODS

Longitudinal data of DLCO, FVC, and ILD on the HRCT of SSc patients from the EUSTAR database were evaluated at baseline (t0) and after 12 (±4) (t1) and 24 (±4) (t2) months.

RESULTS

474/17805 patients were eligible for the study (403 females); 46 (9.7%) developed ILD at t2. Positivity for anti-topoisomerase antibodies (117 patients) showed an association with ILD development at t2 (p = 0.0031). Neither the mean t0 to t1 change (Δ) of DLCO nor the mean t0 to t1 FVCΔ predicted the appearance of ILD at t2. Investigating the possible role of baseline DLCO and FVC values in predicting ILD appearance after 24 (±4) months, we observed a moderate predictive capability of t0 DLCO < 80%, stronger than that of FVC < 80%.

CONCLUSIONS

We suggest that an impaired baseline DLCO may be predictive of the appearance of ILD after 2 years of follow-up. This result advances the hypothesis that a reduction in gas exchange may be considered an early sign of lung involvement. However, further rigorous studies are warranted to understand the predictive role of DLCO evaluation in the course of SSc.

Effects of upadacitinib and PD29 on oxidative damage and inflammation in bleomycin-induced scleroderma model kidney tissues

Objective: Scleroderma (SSc) is a rare autoimmune tissue disease. There is currently no effective treatment for SSc. The aim of this study was to investigate the antioxidant and anti-inflammatory effects of upadacitinib and PD29 on total oxidant status (TOS), total antioxidant status (TAS), malondialdehyde (MDA), catalase (CAT), glutathione (GSH) peroxidase levels, and interleukin-6 (IL-6) and interleukin-13 ( IL-13) in kidney tissues of an experimental SSc model. Materials and Methods: The experimental design was established with five groups of eight mice: Control, bleomycin (BLM) (5 μg/kg), BLM + upadacitinib (3mg/kg), BLM + PD29 (5 mg/kg) and BLM + PD29 + upadacitinib group. BLM was administered subcutaneously once a day for 21 days. PD29 was administered subcutaneously and upadacitinib (gavage) were injected for 21 days. Renal tissues were collected at the end of the experiment. Renal TOS, TAS, MDA, CAT, GSH levels, and IL-6 and IL-13 gene expressions were evaluated. Results: Upadacitinib and PD29 affected oxidant status and TOS. MDA levels decreased, and GSH, CAT, and TAS levels increased. Also, upadacitinib and PD29 decreased inflammation via IL-6 and IL-13 cytokines. Conclusion: Upadacitinib and PD29 may have therapeutic roles for SSc renal crisis.

Role of Extracellular Vesicles in the Propagation of Lung Fibrosis in Systemic Sclerosis

OBJECTIVES

Systemic sclerosis (SSc) has the highest mortality rate among the rheumatic diseases, with lung fibrosis leading as the cause of death. A characteristic of severe SSc-related lung fibrosis is its progressive nature. Although most research has focused on the pathology of the fibrosis, the mechanism mediating the fibrotic spread remains unclear. We hypothesized that extracellular vesicle (EV) communication drives the propagation of SSc lung fibrosis.

METHODS

EVs were isolated from normal (NL) or SSc-derived human lungs and primary lung fibroblasts (pLFs). EVs were also isolated from human fibrotic lungs and pLFs induced experimentally with transforming growth factor-β (TGFβ). Fibrotic potency of EVs was assessed using functional assays in vitro and in vivo. Transmission electron microscopy, nanoparticle tracking analysis, real-time quantitative polymerase chain reaction (RT-qPCR), immunoblotting, and immunofluorescence were used to analyze EVs, their cargo, extracellular matrix (ECM) fractions, and conditioned media.

RESULTS

SSc lungs and pLFs released significantly more EVs than NL lungs, and their EVs showed increased fibrotic content and activity. TGFβ-stimulated NL lung cores and pLFs increased packaging of fibrotic proteins, including fibronectin, collagens, and TGFβ, into released EVs. The EVs induced a fibrotic phenotype in recipient pLFs and in vivo in mouse lungs. Furthermore, EVs interacted with and contributed to the ECM. Finally, suppressing EV release in vivo reduced severity of murine lung fibrosis.

CONCLUSIONS

Our findings highlight EV communication as a novel mechanism for propagation of SSc lung fibrosis. Identifying therapies that reduce EV release, activity, and/or fibrotic cargo in SSc patient lungs may be a viable therapeutic strategy to improve fibrosis.

Targeting the NLRP3 inflammasome and associated cytokines in scleroderma associated interstitial lung disease

SSc-ILD (scleroderma associated interstitial lung disease) is a complex rheumatic disease characterized in part by immune dysregulation leading to the progressive fibrotic replacement of normal lung architecture. Because improved treatment options are sorely needed, additional study of the fibroproliferative mechanisms mediating this disease has the potential to accelerate development of novel therapies. The contribution of innate immunity is an emerging area of investigation in SSc-ILD as recent work has demonstrated the mechanistic and clinical significance of the NLRP3 inflammasome and its associated cytokines of TNFα (tumor necrosis factor alpha), IL-1β (interleukin-1 beta), and IL-18 in this disease. In this review, we will highlight novel pathophysiologic insights afforded by these studies and the potential of leveraging this complex biology for clinical benefit.

Weak to no correlation between quantitative high-resolution computed tomography metrics and lung function change in fibrotic diseases

Background

Identifying systemic sclerosis (SSc) and idiopathic pulmonary fibrosis (IPF) patients at risk of more rapid forced vital capacity (FVC) decline could improve trial design. The purpose of the present study was to explore the prognostic value of quantitative high-resolution computed tomography (HRCT) metrics derived by Imbio lung texture analysis (LTA) tool in predicting FVC slope.

Methods

This retrospective study used data from patients who were not treated with investigational drugs with and without background antifibrotic therapies in tocilizumab phase 3 SSc, lebrikizumab phase 2 IPF, and zinpentraxin alfa phase 2 IPF studies conducted from 2015 to 2021. Controlled HRCT axial volumetric multidetector computed tomography scans were evaluated using the Imbio LTA tool. Associations between HRCT metrics and FVC slope were assessed through the Spearman correlation coefficient and adjusted R2 in a linear regression model adjusted by demographics and baseline clinical characteristics.

Results

A total of 271 SSc and IPF patients were analysed. Correlation coefficients of highest magnitude were observed in the SSc study between the extent of ground glass, normal volume, quantification of interstitial lung disease, reticular pattern, and FVC slope (-0.25, 0.28, -0.28, and -0.33, respectively), while the correlation coefficients observed in IPF studies were in general <0.2. The incremental prognostic value of the baseline HRCT metrics was marginal after adjusting baseline characteristics and was inconsistent across study arms.

Conclusion

Data from the SSc and IPF studies suggested weak to no and inconsistent correlation between quantitative HRCT metrics derived by the Imbio LTA tool and FVC slope in the studied SSc and IPF population.

The Role of SOX9 in IGF-II-Mediated Pulmonary Fibrosis

Pulmonary fibrosis (PF) associated with systemic sclerosis (SSc) results in significant morbidity and mortality. We previously reported that insulin-like growth factor-II (IGF-II) is overexpressed in lung tissues and fibroblasts from SSc patients, and IGF-II fosters fibrosis by upregulating collagen type I, fibronectin, and TGFβ. We now show that IGF-II augments mRNA levels of profibrotic signaling molecules TGFβ2 (p ≤ 0.01) and TGFβ3 (p ≤ 0.05), collagen type III (p ≤ 0.01), and the collagen posttranslational modification enzymes P4HA2 (p ≤ 0.05), P3H2 (p ≤ 0.05), LOX (p = 0.065), LOXL2 (p ≤ 0.05), LOXL4 (p ≤ 0.05) in primary human lung fibroblasts. IGF-II increases protein levels of TGFβ2 (p ≤ 0.01), as well as COL3A1, P4HA2, P4Hβ, and LOXL4 (p ≤ 0.05). In contrast, IGF-II decreases mRNA levels of the collagen degradation enzymes cathepsin (CTS) K, CTSB, and CTSL and protein levels of CTSK (p ≤ 0.05). The SRY-box transcription factor 9 (SOX9) is overexpressed in SSc lung tissues at the mRNA (p ≤ 0.05) and protein (p ≤ 0.01) levels compared to healthy controls. IGF-II induces SOX9 in lung fibroblasts (p ≤ 0.05) via the IGF1R/IR hybrid receptor, and SOX9 regulates TGFβ2 (p ≤ 0.05), TGFβ3 (p ≤ 0.05), COL3A1 (p ≤ 0.01), and P4HA2 (p ≤ 0.001) downstream of IGF-II. Our results identify a novel IGF-II signaling axis and downstream targets that are regulated in a SOX9-dependent and -independent manner. Our findings provide novel insights on the role of IGF-II in promoting pulmonary fibrosis.

Risk factors for lung function decline in systemic sclerosis-associated interstitial lung disease in a large single-centre cohort

OBJECTIVES

The aim of this study was to identify risk factors of percent predicted forced vital capacity (ppFVC) decline in patients with SSc-associated interstitial lung disease (SSc-ILD).

METHODS

We identified 484 patients with SSc who had HRCT Chest, of which 312 with ILD. Those with serial pulmonary function tests were included in a longitudinal analysis (n = 184). Linear mixed effect models were fitted to assess the decline in ppFVC over time, and to explore the effect of demographics and baseline characteristics on ppFVC decline.

RESULTS

The majority of SSc-ILD patients were female (76.3%) and 51.3% had diffuse cutaneous subset. The mean (s.d.) age was 53.6 (12.7) years, median disease duration since first non-RP symptoms was 2.6 years, and 48.4% of the patients had ILD extent >20% on HRCT. In the univariate analysis, longer disease duration (>2.37 years), ILD extent >20%, and anti-topoisomerase I (ATA) positivity were significantly associated with ppFVC decline. In the multivariate analysis, the only statistically significant variable associated with ppFVC decline was ATA positivity. The overall group's mean decline in ppFVC was -0.28% (P-value 0.029), with -0.13% (n = 163) in those who were alive and -8.28% (P-value 0.0002 for the change in ppFVC trajectory) in patients who died within 2 years.

CONCLUSION

Our study confirms that ppFVC is a marker of survival in SSc-ILD, supporting its use for risk stratification to identify patients who may benefit from earlier interventions and treatment. Our study also supports the role of ATA positivity as a predictive marker for ppFVC decline in this population.

The soluble receptor for advanced glycation end products is potentially predictive of pulmonary arterial hypertension in systemic sclerosis

Introduction

Pulmonary arterial hypertension (PAH) and interstitial lung disease (ILD) are the leading causes of death in systemic sclerosis (SSc). Until now, no prospective biomarker to predict new onset of SSc-ILD or SSc-PAH in patients with SSc has reached clinical application. In homeostasis, the receptor for advanced glycation end products (RAGE) is expressed in lung tissue and involved in cell-matrix adhesion, proliferation and migration of alveolar epithelial cells, and remodeling of the pulmonary vasculature. Several studies have shown that sRAGE levels in serum and pulmonary tissue vary according to the type of lung-related complication. Therefore, we investigated levels of soluble RAGE (sRAGE) and its ligand high mobility group box 1 (HMGB1) in SSc and their abilities to predict SSc-related pulmonary complications.

Methods

One hundred eighty-eight SSc patients were followed retrospectively for the development of ILD, PAH, and mortality for 8 years. Levels of sRAGE and HMGB1 were measured in serum by ELISA. Kaplan-Meier survival curves were performed to predict lung events and mortality and event rates were compared with a log-rank test. Multiple linear regression analysis was performed to examine the association between sRAGE and important clinical determinants.

Results

At baseline, levels of sRAGE were significantly higher in SSc-PAH-patients (median 4099.0 pg/ml [936.3-6365.3], p = 0.011) and lower in SSc-ILD-patients (735.0 pg/ml [IQR 525.5-1988.5], p = 0.001) compared to SSc patients without pulmonary involvement (1444.5 pg/ml [966.8-2276.0]). Levels of HMGB1 were not different between groups. After adjusting for age, gender, ILD, chronic obstructive pulmonary disease, anti-centromere antibodies, the presence of puffy fingers or sclerodactyly, use of immunosuppression, antifibrotic therapy, or glucocorticoids, and use of vasodilators, higher sRAGE levels remained independently associated with PAH. After a median follow-up of 50 months (25-81) of patients without pulmonary involvement, baseline sRAGE levels in the highest quartile were predictive of development of PAH (log-rank p = 0.01) and of PAH-related mortality (p = 0.001).

Conclusions

High systemic sRAGE at baseline might be used as a prospective biomarker for patients with SSc at high risk to develop new onset of PAH. Moreover, high sRAGE levels could predict lower survival rates due to PAH in patients with SSc.

Wilms Tumor 1-Driven Fibroblast Activation and Subpleural Thickening in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease that is often fatal due to the formation of irreversible scar tissue in the distal areas of the lung. Although the pathological and radiological features of IPF lungs are well defined, the lack of insight into the fibrogenic role of fibroblasts that accumulate in distinct anatomical regions of the lungs is a critical knowledge gap. Fibrotic lesions have been shown to originate in the subpleural areas and extend into the lung parenchyma through processes of dysregulated fibroproliferation, migration, fibroblast-to-myofibroblast transformation, and extracellular matrix production. Identifying the molecular targets underlying subpleural thickening at the early and late stages of fibrosis could facilitate the development of new therapies to attenuate fibroblast activation and improve the survival of patients with IPF. Here, we discuss the key cellular and molecular events that contribute to (myo)fibroblast activation and subpleural thickening in IPF. In particular, we highlight the transcriptional programs involved in mesothelial to mesenchymal transformation and fibroblast dysfunction that can be targeted to alter the course of the progressive expansion of fibrotic lesions in the distal areas of IPF lungs.

Chronic dyspnea with Raynaud's phenomenon and elevated ANA: A diagnosis of systemic sclerosis sine scleroderma

Systemic sclerosis (SSc) should be considered in all patients initially diagnosed with idiopathic interstitial lung disease (ILD), even in the absence of classical scleroderma cutaneous features. Systemic sclerosis sine scleroderma (ssSSc) is a rare subtype of SSc, and the diagnosis requires the absence of characteristic skin thickening but the presence of the three following criteria: (A) Raynaud's phenomenon or the equivalent of abnormal nail fold capillaries, (B) positive antinuclear antibody (ANA), typically with nucleolar or speckled immunofluorescence pattern, and (C) at least one internal organ involvement of ILD, renal dysfunction, esophageal/bowel dysmotility or pulmonary arterial hypertension; in the absence of an alternative rheumatological diagnosis. The radiological and histopathological features of systemic sclerosis sine scleroderma-associated interstitial lung disease (ssSSc-ILD) are commonly those of non-specific interstitial pneumonia (NSIP) and usual interstitial pneumonia (UIP) that cannot help distinguish between idiopathic interstitial pneumonia, different types of connective tissue diseases, or even different subsets of SSc. Therefore, other than chest imaging, the use of nail fold capillaroscopy, positive serum ANA antibody, echocardiogram, and esophagram are essential, in conjunction with the clinical presentation for facilitating the diagnosis of ssSSc. We present a case of a 58-year-old woman presenting with chronic dyspnea, a positive review of systems for Raynaud's phenomenon, and found to have elevated nucleolar immunofluorescence pattern of ANA with chest imaging consistent with the diagnosis of ssSSc-ILD. The uniqueness of this case is that despite symptomatic alleviation with oral mycophenolate therapy, our patient's restrictive lung disease on pulmonary function tests continued to decline, requiring initiation of oral nintedanib therapy leading to stability and improvement. However, due to the rarity of ssSSc, the use of oral nintedanib for systemic sclerosis-associated ILD has only been formally assessed on patients with diffuse cutaneous systemic sclerosis and limited cutaneous systemic sclerosis.

Ameliorating Fibrosis in Murine and Human Tissues with END55, an Endostatin-Derived Fusion Protein Made in Plants

Organ fibrosis, particularly of the lungs, causes significant morbidity and mortality. Effective treatments are needed to reduce the health burden. A fragment of the carboxyl-terminal end of collagen XVIII/endostatin reduces skin and lung fibrosis. This fragment was modified to facilitate its production in plants, which resulted in the recombinant fusion protein, END55. We found that expression of END55 had significant anti-fibrotic effects on the treatment and prevention of skin and lung fibrosis in a bleomycin mouse model. We validated these effects in a second mouse model of pulmonary fibrosis involving inducible, lung-targeted expression of transforming growth factor β1. END55 also exerted anti-fibrotic effects in human lung and skin tissues maintained in organ culture in which fibrosis was experimentally induced. The anti-fibrotic effect of END55 was mediated by a decrease in the expression of extracellular matrix genes and an increase in the levels of matrix-degrading enzymes. Finally, END55 reduced fibrosis in the lungs of patients with systemic sclerosis (SSc) and idiopathic pulmonary fibrosis (IPF) who underwent lung transplantation due to the severity of their lung disease, displaying efficacy in human tissues directly relevant to human disease. These findings demonstrate that END55 is an effective anti-fibrotic therapy in different organs.

Insulin-like Growth Factor-2 (IGF-2) in Fibrosis

The insulin family consists of insulin, insulin-like growth factor 1 (IGF-1), insulin-like growth factor 2 (IGF-2), their receptors (IR, IGF-1R and IGF-2R), and their binding proteins. All three ligands are involved in cell proliferation, apoptosis, protein synthesis and metabolism due to their homologous sequences and structural similarities. Insulin-like growth factor 2, a member of the insulin family, plays an important role in embryonic development, metabolic disorders, and tumorigenesis by combining with three receptors with different degrees of affinity. The main pathological feature of various fibrotic diseases is the excessive deposition of extracellular matrix (ECM) after tissue and organ damage, which eventually results in organic dysfunction because scar formation replaces tissue parenchyma. As a mitogenic factor, IGF-2 is overexpressed in many fibrotic diseases. It can promote the proliferation of fibroblasts significantly, as well as the production of ECM in a time- and dose-dependent manner. This review aims to describe the expression changes and fibrosis-promoting effects of IGF-2 in the skin, oral cavity, heart, lung, liver, and kidney fibrotic tissues.

Management of progressive pulmonary fibrosis associated with connective tissue disease

INTRODUCTION

: Fibrotic interstitial lung disease (ILD) is a frequent and severe complication of connective tissue disease (CTD).

AREAS COVERED

: In this narrative review, we update the most relevant differential characteristics of fibrotic ILD associated with CTD (CTD-ILD) and propose a diagnostic and therapeutic approach based on a review of the articles published between 2002 and 2022 through PubMed.

EXPERT OPINION

: The subset of ILD, mainly the radiological/histological pattern and the degree of fibrotic component, usually determines the prognosis and therapeutic strategy for these patients. Some patients with CTD-ILD can develop progressive pulmonary fibrosis (PPF) with severe deterioration of lung function, rapid progression to chronic respiratory failure, and high mortality. PPF has been described in many CTDs, mainly in systemic sclerosis and rheumatoid arthritis, and requires a multidisciplinary diagnostic and therapeutic approach to improve patient outcomes.

Scorpion Venom Polypeptide Inhibits Pulmonary Epithelial-Mesenchymal Transition in Systemic Sclerosis-Interstitial Lung Disease Model Mice by Intervening TGF-β1/Smad Signaling Pathway

Objective

Interstitial lung disease (ILD) is an important complication of systemic sclerosis (SSc). The aim of this study was to investigate the effect and possible mechanism of polypeptide extract of scorpion venom (PESV) on SSc-ILD.

Methods

C57/BL6 mice were injected with bleomycin to establish a SSc-ILD model. Different concentrations of PESV solution were administered to SSc-ILD mice, and dexamethasone was used as a positive control. H&E staining and Masson staining were used to observe the pathological changes. The TGF-β1 expression level was detected by immunohistochemistry. The expression of epithelial-mesenchymal transition (EMT)-related proteins was detected by Western blot, and the expression of TGF-β1/Smad pathway-related proteins was also detected. The content of inflammatory cytokines in serum and BALF was determined by ELISA.

Results

Pathological analysis showed that PESV could alleviate SSc-ILD-induced pulmonary inflammation and fibrosis. Compared with the model group, the content of inflammatory cytokines IL-6 and TNF-α significantly decreased after PESV treatment. PESV could increase the expression of epithelial marker (E-cadherin) and reduce the expression of interstitial markers (collagen I, vimentin, N-cadherin, and a-SMA). In addition, PESV could reduce the expression level of TGF-β1/Smad pathway-related protein.

Conclusion

PESV can attenuate SSc-ILD by regulating EMT, and the effect was linked to the TGF-β1/Smad signaling pathway, which indicated that PESV may serve as a candidate drug for SSc-ILD.

Increased risk of mortality in systemic sclerosis-associated pulmonary hypertension: a systemic review and meta-analysis

BACKGROUND

Pulmonary hypertension (PH) is a frequent complication of systemic sclerosis (SSc) and is currently one of the primary causes of death in patients with this disease. We conducted a systematic review and meta-analysis to assess the association between PH and mortality in patients with SSc to verify trends in mortality in patients with SSc-associated PH.

METHODS

We searched the PubMed and Embase databases for published studies on SSc-associated PH from inception to May 2021. All cohort studies in which mortality and/or survival for SSc-associated PH were reported were included in the analysis. The outcome parameters were pooled and analyzed using a random-effects model via generic inverse-variance weighting in conventional and cumulative meta-analysis.

RESULTS

The literature search identified 1161 citations, and the full texts of 54 studies were examined. Sixteen articles, with a total of 7857 patients with SSc and 1140 patients with SSc-associated PH, were included in the meta-analysis. Patients with SSc-associated PH had a higher pooled risk of mortality than patients with SSc without PH (risk ratio = 3.12; 95% confidence interval: [2.44, 3.98]).

CONCLUSIONS

This meta-analysis revealed a higher mortality in patients with SSc-associated PH. PH was a significant predictor of death in patients with SSc. Thus, early diagnosis and treatment of PH are important in patients with SSc.

The Downregulation of PTGS2 Mediated by ncRNAs is Tightly Correlated with Systemic Sclerosis-Interstitial Lung Disease

Background: Interstitial lung disease in systemic sclerosis (SSc-ILD) is one of the most severe complications of systemic sclerosis (SSc) and is the main cause of mortality. In this study, we aimed to explore the key genes in SSc-ILD and analyze the relationship between key genes and immune cell infiltration as well as the key genes relevant to the hallmarks of cancer.

Methods: Weighted gene co-expression network analysis (WGCNA) algorithm was implemented to explore hub genes in SSc-ILD samples from the Gene Expression Omnibus (GEO) database. Logistic regression analysis was performed to screen and verify the key gene related to SSc-ILD. CIBERSORT algorithms were utilized to analyze immune cell infiltration. Moreover, the correlation between the key genes and genes relevant to cancer was also evaluated. Furthermore, non-coding RNAs (ncRNAs) linking to PTGS2 were also explored.

Results: In this study, we first performed WGCNA analysis for three GEO databases to find the potential hub genes in SSc-ILD. Subsequently, we determined PTGS2 was the key gene in SSC-ILD. Furthermore, in CIBERSORT analyses, PTGS2 were tightly correlated with immune cells such as regulatory T cells (Tregs) and was negatively correlated with CD20 expression. Moreover, PTGS2 was associated with tumor growth. Then, MALAT1, NEAT1, NORAD, XIST identified might be the most potential upstream lncRNAs, and LIMS1 and RANBP2 might be the two most potential upstream circRNAs.

Conclusion: Collectively, our findings elucidated that ncRNAs-mediated downregulation of PTGS2, as a key gene in SSc-ILD, was positively related to the occurrence of SSc-ILD and abnormal immunocyte infiltration. It could be a promising factor for SSc-ILD progression to malignancy.

The role of antifibrotic therapies in the treatment of systemic sclerosis-associated interstitial lung disease

Systemic sclerosis (SSc) is a rare autoimmune condition with complex pathogenesis characterized by a heterogeneous presentation and different disease courses. Fibrosis of multiple organs including the lungs favored by inflammation and vasculopathy is the hallmark of SSc. SSc-associated interstitial lung disease (SSc-ILD) is common and can be associated with poor outcomes, this complication being the leading cause of death in recent series. Because of its huge heterogeneity, SSc-ILD management can be very challenging. Immunosuppressive therapy has long been used to prevent SSc-ILD progression with modest effects in clinical trials. However, thanks to a better understating of SSc pathogenesis, innovative therapies including antifibrotics are increasingly being developed. The achievement of the Safety and Efficacy of Nintedanib in Systemic SClerosIS (SENSCIS) trial has led to the approval by drug agencies of the first antifibrotic drug for SSc-ILD. In parallel, other antifibrotics are being investigated as possible beneficial therapies in SSc-ILD. An important unmet need remains to clarify the positioning of the various strategies, such as the added value of combination of immunosuppressants and antifibrotic therapies in patients at high risk of progression. Indeed, irreversible lung injury or self-perpetuated progression highlights the concept of a window of opportunity in SSc-ILD patients. Herewith, we provide an overview of the most significant clinical trials with antifibrotic drugs developed in recent years for the management of SSc-ILD and a viewpoint about their positioning in treatment algorithms.

Single Cell RNA Sequencing in Autoimmune Inflammatory Rheumatic Diseases: Current Applications, Challenges and a Step Toward Precision Medicine

Single cell RNA sequencing (scRNA-seq) represents a new large scale and high throughput technique allowing analysis of the whole transcriptome at the resolution of an individual cell. It has emerged as an imperative method in life science research, uncovering complex cellular networks and providing indices that will eventually lead to the development of more targeted and personalized therapies. The importance of scRNA-seq has been particularly highlighted through the analysis of complex biological systems, in which cellular heterogeneity is a key aspect, such as the immune system. Autoimmune inflammatory rheumatic diseases represent a group of disorders, associated with a dysregulated immune system and high patient heterogeneity in both pathophysiological and clinical aspects. This complicates the complete understanding of underlying pathological mechanisms, associated with limited therapeutic options available and their long-term inefficiency and even toxicity. There is an unmet need to investigate, in depth, the cellular and molecular mechanisms driving the pathogenesis of rheumatic diseases and drug resistance, identify novel therapeutic targets, as well as make a step forward in using stratified and informed therapeutic decisions, which could now be achieved with the use of single cell approaches. This review summarizes the current use of scRNA-seq in studying different rheumatic diseases, based on recent findings from published in vitro, in vivo, and clinical studies, as well as discusses the potential implementation of scRNA-seq in the development of precision medicine in rheumatology.

E4 engages uPAR and enolase-1 and activates urokinase to exert antifibrotic effects

Fibroproliferative disorders such as systemic sclerosis (SSc) have no effective therapies and result in significant morbidity and mortality. We recently demonstrated that the C-terminal domain of endostatin, known as E4, prevented and reversed both dermal and pulmonary fibrosis. Our goal was to identify the mechanism by which E4 abrogates fibrosis and its cell surface binding partner(s). Our findings show that E4 activated the urokinase pathway and increased the urokinase plasminogen activator (uPA) to type 1 plasminogen activator inhibitor (PAI-1) ratio. In addition, E4 substantially increased MMP-1 and MMP-3 expression and activity. In vivo, E4 reversed bleomycin induction of PAI-1 and increased uPA activity. In patients with SSc, the uPA/PAI-1 ratio was decreased in both lung tissues and pulmonary fibroblasts compared with normal donors. Proteins bound to biotinylated-E4 were identified as enolase-1 (ENO) and uPA receptor (uPAR). The antifibrotic effects of E4 required uPAR. Further, ENO mediated the fibrotic effects of TGF-β1 and exerted TGF-β1–independent fibrotic effects. Our findings suggest that the antifibrotic effect of E4 is mediated, in part, by regulation of the urokinase pathway and induction of MMP-1 and MMP-3 levels and activity in a uPAR-dependent manner, thus promoting extracellular matrix degradation. Further, our findings identify a moonlighting function for the glycolytic enzyme ENO in fibrosis.

Parvovirus B19 (B19V) induces cellular senescence in human dermal fibroblasts: putative role in SSc-associated fibrosis

OBJECTIVE

Emerging evidence demonstrates that excessive accumulation of senescent cells is associated with some chronic diseases and suggests a pathogenic role of cellular senescence in fibrotic processes, such as that occurring in aging or in systemic sclerosis (SSc). Recently, we demonstrated that parvovirus B19 (B19V) activates normal human dermal fibroblasts and induces expression of different profibrotic/proinflammatory genes. This observation prompted us to investigate whether it is also able to induce fibroblast senescence as a potential pathogenetic mechanism in B19V-induced fibrosis.

METHODS

Primary cultures of fibroblasts were infected with B19V and analyzed for the acquisition of senescence markers, such as morphological modifications, senescence-associated beta-galactosidase (SA-β-gal) activity, DNA damage response (DDR) and expression of senescence-associated secretory phenotype (SASP)-related factors.

RESULTS

We demonstrated that B19V-infected fibroblasts develop typical senescence features such as enlarged and flat-shaped morphology and SA-β-gal activity similar to that observed in SSc skin fibroblasts. They also developed a SASP-like phenotype characterized by mRNA expression and release of some proinflammatory cytokines, along with activation of transcription factor NFkB. Moreover, we observed B19V-induced DNA damage with the comet assay: a subpopulation of fibroblasts from B19V-infected cultures showed a significant higher level of DNA strand breaks and oxidative damage compared with mock-infected cells. Increased level and nuclear localization of ɣH2AX, a hallmark of DNA damage response, were also found.

CONCLUSIONS

B19V-induced senescence and production of SASP-like factors in normal dermal fibroblasts could represent a new pathogenic mechanism of non-productive B19V infection, which may have a role in the fibrotic process.

Connective Tissue Growth Factor Single Nucleotide Polymorphisms in (Familial) Pulmonary Fibrosis and Connective Tissue Disease Associated Interstitial Lung Disease

PURPOSE

Connective tissue growth factor (CTGF) is an important mediator in fibrotic disease. Single nucleotide polymorphisms (SNPs) in CTGF have been found to be associated with different fibrotic diseases and CTGF protein was found to be upregulated in lung tissue, bronchoalveolar lavage cells, and plasma of idiopathic pulmonary fibrosis (IPF) patients. We investigated whether genetic variants predispose to sporadic IPF (spIPF), familial pulmonary fibrosis (FPF), and connective tissue disease associated ILD (CTD-ILD).

METHODS

In total, 294 patients with spIPF and 294 healthy individuals were genotyped for CTGF rs12526196, rs9402373, rs6918698, and rs9399005. For replication of CTGF rs6918698 findings in pulmonary fibrosis, 128 patients with FPF, 125 with CTD-ILD, and an independent control cohort of 130 individuals were included. Lung tissue of 6 IPF patients was stained for CTGF to assess pulmonary localization.

RESULTS

Of the four SNPs, only the minor allele frequency (MAF) of CTGF rs6918698 deviated between spIPF (MAF 0.41) and controls (MAF 0.47; OR 0.774 (0.615-0.975); p = 0.030). Further comparison of CTGF rs6918698G showed a difference between FPF (MAF 0.33) and controls (MAF 0.48; OR 0.545 (0.382-0.778); p = 0.001), but not with CTD-ILD. CTGF was localized in alveolar and bronchiolar epithelium, alveolar macrophages, myofibroblasts and endothelium and highly expressed in the basal cell layer of sandwich foci.

CONCLUSION

CTGF rs6918698G associates with spIPF and with FPF, but not with CTD-ILD in a Dutch cohort. CTGF is localized in lung tissue involved in IPF pathogenesis. Further research into the role of this SNP on CTGF expression and fibrogenesis is warranted.

Identification of Impacted Pathways and Transcriptomic Markers as Potential Mediators of Pulmonary Fibrosis in Transgenic Mice Expressing Human IGFBP5

Pulmonary fibrosis is a serious disease characterized by extracellular matrix (ECM) component overproduction and remodeling. Insulin-like growth factor-binding protein 5 (IGFBP5) is a conserved member of the IGFBP family of proteins that is overexpressed in fibrotic tissues and promotes fibrosis. We used RNA sequencing (RNAseq) to identify differentially expressed genes (DEGs) between primary lung fibroblasts (pFBs) of homozygous (HOMO) transgenic mice expressing human IGFBP5 (hIGFBP5) and wild type mice (WT). The results of the differential expression analysis showed 2819 DEGs in hIGFBP5 pFBs. Functional enrichment analysis confirmed the pro-fibrotic character of IGFBP5 and revealed its impact on fundamental signaling pathways, including cytokine–cytokine receptor interaction, focal adhesion, AGE-RAGE signaling, calcium signaling, and neuroactive ligand-receptor interactions, to name a few. Noticeably, 7% of the DEGs in hIGFBP5-expressing pFBs are receptors and integrins. Furthermore, hub gene analysis revealed 12 hub genes including Fpr1, Bdkrb2, Mchr1, Nmur1, Cnr2, P2ry14, and Ptger3. Validation assays were performed to complement the RNAseq data. They confirmed significant differences in the levels of the corresponding proteins in cultured pFBs. Our study provides new insights into the molecular mechanism(s) of IGFBP5-associated pulmonary fibrosis through possible receptor interactions that drive fibrosis and tissue remodeling.

A Machine Learning Application to Predict Early Lung Involvement in Scleroderma: A Feasibility Evaluation

Introduction: Systemic sclerosis (SSc) is a systemic immune-mediated disease, featuring fibrosis of the skin and organs, and has the greatest mortality among rheumatic diseases. The nervous system involvement has recently been demonstrated, although actual lung involvement is considered the leading cause of death in SSc and, therefore, should be diagnosed early. Pulmonary function tests are not sensitive enough to be used for screening purposes, thus they should be flanked by other clinical examinations; however, this would lead to a risk of overtesting, with considerable costs for the health system and an unnecessary burden for the patients. To this extent, Machine Learning (ML) algorithms could represent a useful add-on to the current clinical practice for diagnostic purposes and could help retrieve the most useful exams to be carried out for diagnostic purposes. Method: Here, we retrospectively collected high resolution computed tomography, pulmonary function tests, esophageal pH impedance tests, esophageal manometry and reflux disease questionnaires of 38 patients with SSc, applying, with R, different supervised ML algorithms, including lasso, ridge, elastic net, classification and regression trees (CART) and random forest to estimate the most important predictors for pulmonary involvement from such data. Results: In terms of performance, the random forest algorithm outperformed the other classifiers, with an estimated root-mean-square error (RMSE) of 0.810. However, this algorithm was seen to be computationally intensive, leaving room for the usefulness of other classifiers when a shorter response time is needed. Conclusions: Despite the notably small sample size, that could have prevented obtaining fully reliable data, the powerful tools available for ML can be useful for predicting early lung involvement in SSc patients. The use of predictors coming from spirometry and pH impedentiometry together might perform optimally for predicting early lung involvement in SSc.

Distinct Metalloproteinase Expression and Functions in Systemic Sclerosis and Fibrosis: What We Know and the Potential for Intervention

Systemic sclerosis (SSc) is a chronic debilitating idiopathic disorder, characterized by deposition of excessive extracellular matrix (ECM) proteins such as collagen which leads to fibrosis of the skin and other internal organs. During normal tissue repair and remodeling, the accumulation and turnover of ECM proteins are tightly regulated by the interaction of matrix metalloproteinases (MMPs) and endogenous tissue inhibitors of metalloproteinases (TIMPs). SSc is associated with dysregulation of the activity of these proteolytic and inhibitory proteins within the tissue microenvironment, tipping the balance toward fibrosis. The resultant ECM accumulation further perpetuates tissue stiffness and decreased function, contributing to poor clinical outcomes. Understanding the expression and function of these endogenous enzymes and inhibitors within specific tissues is therefore critical to the development of therapies for SSc. This brief review describes recent advances in our understanding of the functions and mechanisms of ECM remodeling by metalloproteinases and their inhibitors in the skin and lungs affected in SSc. It highlights recent progress on potential candidates for intervention and therapeutic approaches for treating SSc fibrosis.

An IPF-like disease course in disorders other than IPF: how can this be anticipated, recognized, and managed?

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF)-like chronic disease progression despite treatment cannot be predicted with confidence in interstitial lung diseases (ILDs) other than IPF at the time of diagnosis.

AREAS COVERED

We review key determinants of a progressive fibrotic phenotype, at initial diagnosis of an ILD other than IPF. Medline literature searches (2000 to 2020) were undertaken with regard to the issues discussed in this review.

EXPERT OPINION

The definition of the progressive fibrotic phenotype in non-IPF patients should remain real world, with a conclusion reached by an experienced clinician that progression has occurred despite the use of appropriate historical therapies, on a case by case basis. There is an urgent need for pathogenetic studies to identify pathways and genetic predilections that are common to chronic progressive fibrosis across different diseases. Efforts should also be focused on the identification of the progressive fibrotic phenotype at first presentation, potentially through a combination of CT and biopsy evaluation and the definition of a biomarker profile associated with subsequent disease progression. Recent anti-fibrotic trials of non-IPF disorders should lead to trials of combination regimens of anti-fibrotic agents and immunomodulatory or other therapies specific to individual diseases.

Integrative analysis of lung molecular signatures reveals key drivers of systemic sclerosis-associated interstitial lung disease

OBJECTIVES

Interstitial lung disease is a significant comorbidity and the leading cause of mortality in patients with systemic sclerosis. Transcriptomic data of systemic sclerosis-associated interstitial lung disease (SSc-ILD) were analysed to evaluate the salient molecular and cellular signatures in comparison with those in related pulmonary diseases and to identify the key driver genes and target molecules in the disease module.

METHODS

A transcriptomic dataset of lung tissues from patients with SSc-ILD (n=52), idiopathic pulmonary fibrosis (IPF) (n=549), non-specific interstitial pneumonia (n=49) and pulmonary arterial hypertension (n=81) and from normal healthy controls (n=331) was subjected to filtration of differentially expressed genes, functional enrichment analysis, network-based key driver analysis and kernel-based diffusion scoring. The association of enriched pathways with clinical parameters was evaluated in patients with SSc-ILD.

RESULTS

SSc-ILD shared key pathogenic pathways with other fibrosing pulmonary diseases but was distinguishable in some pathological processes. SSc-ILD showed general similarity with IPF in molecular and cellular signatures but stronger signals for myofibroblasts, which in SSc-ILD were in a senescent and apoptosis-resistant state. The p53 signalling pathway was the most enriched signature in lung tissues and lung fibroblasts of SSc-ILD, and was significantly correlated with carbon monoxide diffusing capacity of lung, cellular senescence and apoptosis. EEF2, EFF2K, PHKG2, VCAM1, PRKACB, ITGA4, CDK1, CDK2, FN1 and HDAC1 were key regulators with high diffusion scores in the disease module.

CONCLUSIONS

Integrative transcriptomic analysis of lung tissues revealed key signatures of fibrosis in SSc-ILD. A network-based Bayesian approach provides deep insights into key regulatory genes and molecular targets applicable to treating SSc-ILD.

Diagnosis and Management of Fibrotic Interstitial Lung Diseases

Nonidiopathic pulmonary fibrosis (non-IPF) progressive fibrotic interstitial lung diseases (PF-ILDs) are a heterogeneous group of ILDs, often challenging to diagnose, although an accurate diagnosis has significant implications for both treatment and prognosis. A subgroup of these patients experiences progressive deterioration in lung function, physical performance, and quality of life after conventional therapy. Risk factors for ILD progression include older age, lower baseline pulmonary function, and a usual interstitial pneumonia pattern. Management of non-IPF P-ILD is both pharmacologic and nonpharmacologic. Antifibrotic drugs, originally approved for IPF, have been considered in patients with other fibrotic ILD subtypes, with favorable results in clinical trials.

Systemic Sclerosis Associated Interstitial Lung Disease and Nintedanib: A Rare Disease and a Promising Drug

Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is a rare disease with a progressive nature, eventually leading to lung fibrosis. Nintedanib, a tyrosine kinase inhibitor, is a widely accepted drug for treating idiopathic pulmonary fibrosis (IPF), a disease that shares some similarities with SSc-ILD regarding pathological disease processes. In this review, we aim to discuss the pathogenesis of SSc-ILD and the overall role of nintedanib in the management of SSc-ILD. SSc-ILD involves multiple pathological mediators contributing to various pathways that ultimately cause lung fibrosis. The pathogenesis of SSc-ILD is a complex phenomenon and still needs further study. Nintedanib has demonstrated its efficacy in the treatment of SSc-ILD by reducing the progression of the pathological process. It has also proven its clinical significance in the management of SSc-ILD. However, the currently available literature does not have any evidence to compare the effectiveness of nintedanib with the already available treatment modalities such as cyclophosphamide (CYC), mycophenolate mofetil (MMF), and azathioprine (AZT). The current literature also lacks information about nintedanib's long-term consequences on patients with SSc-ILD. Therefore, to create better evidence-based treatment guidelines, we recommend that researchers conduct randomized clinical trials comparing nintedanib to MMF, CYC, AZT, etc., and continue surveillance to explore the long-term consequences of nintedanib.

Autoantibodies targeting telomere-associated proteins in systemic sclerosis

OBJECTIVES

Systemic sclerosis (SSc) is an autoimmune fibrotic disease affecting multiple tissues including the lung. A subset of patients with SSc with lung disease exhibit short telomeres in circulating lymphocytes, but the mechanisms underlying this observation are unclear.

METHODS

Sera from the Johns Hopkins and University of California, San Francisco (UCSF) Scleroderma Centers were screened for autoantibodies targeting telomerase and the shelterin proteins using immunoprecipitation and ELISA. We determined the relationship between autoantibodies targeting the shelterin protein TERF1 and telomere length in peripheral leucocytes measured by qPCR and flow cytometry and fluorescent in situ hybridisation (Flow-FISH). We also explored clinical associations of these autoantibodies.

RESULTS

In a subset of patients with SSc, we identified autoantibodies targeting telomerase and the shelterin proteins that were rarely present in rheumatoid arthritis, myositis and healthy controls. TERF1 autoantibodies were present in 40/442 (9.0%) patients with SSc and were associated with severe lung disease (OR 2.4, p=0.04, Fisher's exact test) and short lymphocyte telomere length. 6/6 (100%) patients with TERF1 autoantibodies in the Hopkins cohort and 14/18 (78%) patients in the UCSF cohort had a shorter telomere length in lymphocytes or leukocytes, respectively, relative to the expected age-adjusted telomere length. TERF1 autoantibodies were present in 11/152 (7.2%) patients with idiopathic pulmonary fibrosis (IPF), a fibrotic lung disease believed to be mediated by telomere dysfunction.

CONCLUSIONS

Autoantibodies targeting telomere-associated proteins in a subset of patients with SSc are associated with short lymphocyte telomere length and lung disease. The specificity of these autoantibodies for SSc and IPF suggests that telomere dysfunction may have a distinct role in the pathogenesis of SSc and pulmonary fibrosis.

Case Report: Systemic Sclerosis After Covid-19 Infection

The coronavirus disease (COVID-19) is a respiratory tract infection caused by the new virus SARS-CoV-2. The acute phase of the infection may in certain individuals be followed by another longer phase of disease (long COVID) of unknown etiology probably associated in certain cases with autoimmune activation. It has been shown that COVID-19 can trigger autoantibody production and in genetically predisposed patients may cause the onset or exacerbation of autoimmune diseases. We are reporting a case of mild COVID-19 infection complicated by autoantibody production and cutaneous and gastrointestinal symptoms and subsequently diagnosed with systemic sclerosis (SSc). A 47-year-old man with no history of any autoimmune diseases and in good health became sick together with his family on the 12th of November with mild symptoms: tiredness, fever, cough, and sore throat. Oropharyngeal swab for SARS-CoV-2 tested positive. He was isolated at home and did not require hospitalization. Three weeks later he presented with clinical manifestation compatible with suspicion of SSc. He briefly presented with skin rush, periorbital edema and conjunctivitis, vomiting, dysphagia, burning sensation in the skin, above all in the fingertips and around the mouth, puffy fingers, Raynaud’s phenomenon, pain at the fingertip of the middle finger where a depressed area was noticed without a clear ulceration. ANA showed a strongly positive nucleolar pattern. Anti-PM/Scl 75 and PM/Scl 100 resulted positive. High-resolution computed tomography (HCRT) showed early stage of interstitial lung disease (ILD). The patient was diagnosed with SSc based on the persistence of autoantibodies and the clinical and radiological pictures according to the ACR/EULAR classification (scores: puffy finger, 2; ILD, 2; Raynaud’s phenomenon, 3; SSc related antibodies, 3; total 10). There are several cases described in the medical literature of possible new onset of SLE after COVID-19 infection. This is the first case that describes a possible new onset of SSc. Conclusion: SARS-CoV-2 may trigger systemic sclerosis.

Idiopathic pulmonary fibrosis and systemic sclerosis: pathogenic mechanisms and therapeutic interventions

Fibrotic diseases take a very heavy toll in terms of morbidity and mortality equal to or even greater than that caused by metastatic cancer. In this review, we examine the pathogenesis of fibrotic diseases, mainly addressing triggers for induction, processes that lead to progression, therapies and therapeutic trials. For the most part, we have focused on two fibrotic diseases with lung involvement, idiopathic pulmonary fibrosis, in which the contribution of inflammatory mechanisms may be secondary to non-immune triggers, and systemic sclerosis in which the contribution of adaptive immunity may be predominant.

The Conundrum of 'Long-COVID-19': A Narrative Review

COVID-19 is an ongoing pandemic with many challenges that are now extending to its intriguing long-term sequel. 'Long-COVID-19' is a term given to the lingering or protracted illness that patients of COVID-19 continue to experience even in their post-recovery phase. It is also being called 'post-acute COVID-19', 'ongoing symptomatic COVID-19', 'chronic COVID-19', 'post COVID-19 syndrome', and 'long-haul COVID-19'. Fatigue, dyspnea, cough, headache, brain fog, anosmia, and dysgeusia are common symptoms seen in Long-COVID-19, but more varied and debilitating injuries involving pulmonary, cardiovascular, cutaneous, musculoskeletal and neuropsychiatric systems are also being reported. With the data on Long-COVID-19 still emerging, the present review aims to highlight its epidemiology, protean clinical manifestations, risk predictors, and management strategies. With the re-emergence of new waves of SARS-CoV-2 infection, Long-COVID-19 is expected to produce another public health crisis on the heels of current pandemic. Thus, it becomes imperative to emphasize this condition and disseminate its awareness to medical professionals, patients, the public, and policymakers alike to prepare and augment health care facilities for continued surveillance of these patients. Further research comprising cataloging of symptoms, longer-ranging observational studies, and clinical trials are necessary to evaluate long-term consequences of COVID-19, and it warrants setting-up of dedicated, post-COVID care, multi-disciplinary clinics, and rehabilitation centers.

Serum IGFBP-2 in systemic sclerosis as a prognostic factor of lung dysfunction

Systemic sclerosis (SSc) is a rare connective tissue disease associated with rapid evolving interstitial lung disease (ILD), driving its mortality. Specific biomarkers associated with the progression of this lung disease are highly needed. We aimed to identify specific biomarkers of SSc-ILD to predict the evolution of the disease. For this, we compared prospectively serum levels of several biomarkers associated with lung fibrosis in SSc patients (n = 102), among which SSc-no ILD (n = 63) and SSc-ILD (n = 39), compared to healthy subjects (HS) (n = 39). We also performed a longitudinal study in a subgroup of 28 patients analyzing biomarkers variations and pulmonary function tests over a period of 2 years. Serum level of IGFBP-2 was significantly increased in SSc patients compared to HS, and negatively correlated with pulmonary function (assessed by carbon monoxide transfer coefficient (KCO)) (r = - 0.29, p < 0.01). Two-year longitudinal analysis in a subgroup of 28 SSc patients determined that IGFBP-2 variation was positively correlated with KCO at 2-year follow-up (r = 0.6, p < 0.001). SSc patients with a lower variation of IGFBP-2 (less than 22%) presented significant deterioration of pulmonary function at 2-year follow-up (p < 0.01). ROC curve analysis enabled us to identify that baseline IGFBP-2 > 105 ng/ml was associated with a poor outcome (KCO < 70% predicted) at 2-year follow-up (AUC = 0.75, p < 0.05). We showed for the first time that serum levels of IGFBP-2 might be a prognostic factor of the development of SSc-ILD.

Inflammatory profile of induced sputum composition in systemic sclerosis and comparison with healthy volunteers

Systemic sclerosis (SSc) is a potentially serious and disabling connective tissue disease specially in case of interstitial lung disease (SSc-ILD). The aim of our study was to evaluate the potential utility of dosing in the induced sputum (IS) and to compare their levels in SSc-ILD and SSc-nonILD patients, as well as in healthy volunteers (HV). IS and sera values were also compared. In a prospective cross-sectional analysis, we studied the IS and serum provided from 25 SSc patients, 15 SSc-nonILD and 10 SSc-ILD, compared to 25 HV. We analyzed sputum cell composition and quantified in the supernatant and corresponding serum by commercially available immunoassays: IGFBP-1, IGFBP-2, IGFBP-3, TGF-β, IL-8, TNF-α, YKL-40, MMP-7 and MMP-9. Lung function was studied by the determination of FEV-1 (%), FVC (%), DLCO (%) and KCO (%). The IS of SSc patients had a lower weight than HV (p<0.05, p<0.01) without any significant difference with regard to the cellularity. IGFBP-1 (p < 0.0001), TGF-β (p < 0.05), IL-8 (p < 0.05), YKL-40 (p < 0.0001) and MMP-7 (p < 0.01) levels were increased in the IS of SSc patients compared to HV. Only IL-8 serum levels (p < 0.001) were increased in SSc patients compared to HV. Neither in IS nor in serum were observed differences between SSc-ILD and SSc-nonILD patients. Correlations were observed between IS IL-8 levels and FEV-1 (%) (r =  = − 0.53, p < 0.01), FVC (%) (r = − 0.51, p < 0.01) and annualized ∆KCO (%) (r = 0.57, p < 0.05), between IS TGF-β levels and annualized ∆FEV-1 (%) (r =  = − 0.57, p < 0.05), between IS IGFBP-2 levels and annualized ∆KCO (%) (r = 0.56, p < 0.05). Our study showed that SSc patients exhibit raised IS levels of IGFBP-1, TGF-β, IL-8, YKL-40 and MMP-7, molecules known to be involved in lung remodeling and fibrotic process, without any significant difference between SSc-ILD and SSc-nonILD patients. IL-8, TGF-β and IGFBP-2 are correlated with lung function in SSc patients which emphasize clinical relevance. IS analysis represents a new approach to understand lung inflammatory process in SSc patients. A longitudinal study is needed to evaluate their pathophysiological relevance.

Breathomics to diagnose systemic sclerosis using thermal desorption and comprehensive two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry

Systemic sclerosis is a rare autoimmune disease associated with rapidly evolving interstitial lung disease, responsible for the disease severity and mortality. Specific biomarkers enabling the early diagnosis and prognosis associated with the disease progression are highly needed. Volatile organic compounds in exhaled breath are widely available and non-invasive and have the potential to reflect metabolic processes occurring within the body. Comprehensive two-dimensional gas chromatography coupled to high-resolution mass spectrometry was used to investigate the potential of exhaled breath to diagnose systemic sclerosis. The exhaled breath of 32 patients and 30 healthy subjects was analyzed. The high resolving power of this approach enabled the detection of 356 compounds in the breath of systemic sclerosis patients, which was characterized by an increase of mainly terpenoids and hydrocarbons. In addition, the use of 4 complementary statistical approaches (two-tailed equal variance t-test, fold change, partial least squares discriminant analysis, and random forest) resulted in the identification of 16 compounds that can be used to discriminate systemic sclerosis patients from healthy subjects. Receiver operating curves were generated that provided an accuracy of 90%, a sensitivity of 92%, and a specificity of 89%. The chemical identification of eight compounds predictive of systemic sclerosis was validated using commercially available standards. The analytical variations together with the volatile composition of room air were carefully monitored during the timeframe of the study to ensure the robustness of the technique. This study represents the first reported evaluation of exhaled breath analysis for systemic sclerosis diagnosis and provides surrogate markers for such disease.

Systemic Sclerosis and Associated Interstitial Lung Disease in Ontario, Canada: An Examination of Prevalence and Survival Over 10 Years

OBJECTIVE

Systemic sclerosis (SSc) is a rare autoimmune disease. Pulmonary complications of SSc are some of the leading causes of morbidity and mortality. The objective of this study was to determine prevalence and survival estimates of SSc and SSc with interstitial lung disease (SSc-ILD) in the Canadian province of Ontario using administrative data over 10 years.

METHODS

Using International Classification of Diseases, 10th revision codes adapted for Canada (ICD-10-CA), adult patients diagnosed with SSc and SSc-ILD between April 1, 2008, and March 31, 2018, were identified from the National Ambulatory Care Reporting System and the Discharge Abstract Database administrative databases. SSc was identified first, and ILD was included if presence occurred after SSc diagnosis. Prevalence estimates were determined for both SSc and SSc-ILD. For survival rates, Kaplan-Meier survival curves were generated.

RESULTS

At the start of the 2017/18 fiscal year (final year of the cohort), there were 2114 prevalent SSc cases for a cumulative prevalence of 19.1 per 100,000 persons, as well as 257 prevalent cases of SSc-ILD that generated a prevalence of 2.3 cases per 100,000 persons. Mean ages were 57 and 58 years with 84% and 80% females for patients with SSc and SSc-ILD, respectively. One-, 5-, and 10-year survival rates were 85.0%, 64.5%, and 44.9% for the SSc group and 77.1%, 44.4%, and 22.0% for the SSc-ILD group, respectively.

CONCLUSION

To our knowledge, this study provides the first population-based estimates of SSc and SSc-ILD in Canada for prevalence and survival. Results confirm that the prevalence estimates of SSc-ILD fall within the Canadian threshold for rare disease. It also demonstrates the poor survival in SSc, especially when ILD is also present.

Natural variability in the disease course of SSc-ILD: implications for treatment

Interstitial lung disease (ILD) affects approximately 50% of patients with systemic sclerosis (SSc) and is the leading cause of death in SSc. Our objective was to gain insight into the progression of SSc-associated ILD (SSc-ILD). Using data from longitudinal clinical trials and observational studies, we assessed definitions and patterns of progression, risk factors for progression, and implications for treatment. SSc-ILD progression was commonly defined as exceeding specific thresholds of lung function worsening and/or increasing radiographic involvement. One definition used in several studies is decline in forced vital capacity (FVC) of ≥10%, or ≥5-10% plus a decline in diffusing capacity of the lung for carbon monoxide ≥15%. Based on these criteria, 20-30% of patients in observational cohorts develop progressive ILD, starting early in the disease course and progressing at a highly variable rate.Risk factors such as age, FVC, extent of fibrosis and presence of anti-topoisomerase I antibodies can help predict progression of SSc-ILD, though composite risk scores may offer greater predictive power. Whilst the variability of the disease course in SSc-ILD makes risk stratification of patients challenging, the decision to initiate, change or stop treatment should be based on a combination of the current disease state and the speed of progression.

Disparate Interferon Signaling and Shared Aberrant Basaloid Cells in Single-Cell Profiling of Idiopathic Pulmonary Fibrosis and Systemic Sclerosis-Associated Interstitial Lung Disease

Idiopathic pulmonary fibrosis (IPF) and systemic sclerosis-associated interstitial lung disease (SSc-ILD) differ in the predominant demographics and identified genetic risk alleles of effected patients, however both diseases frequently progress to respiratory failure and death. Contrasting advanced SSc-ILD to IPF provides insight to the role dysregulated immunity may play in pulmonary fibrosis. To analyze cell-type specific transcriptome commonalities and differences between IPF and SSc-ILD, we compared single-cell RNA-sequencing (scRNA-seq) of 21 explanted lung tissue specimens from patients with advanced IPF, SSc-ILD, and organ donor controls. Comparison of IPF and SSc-ILD tissue identified divergent patterns of interferon signaling, with interferon-gamma signaling upregulated in the SPP1hi and FABP4hi macrophages, cytotoxic T cells, and natural kill cells of IPF, while type I interferon signaling and production was upregulated in the corresponding SSc-ILD populations. Plasmacytoid dendritic cells were found in diseased lungs only, and exhibited upregulated cellular stress pathways in SSc-ILD compared to IPF. Alveolar type I cells were dramatically decreased in both IPF and SSc-ILD, with a distinct transcriptome signature separating these cells by disease. KRT5-/KRT17+ aberrant basaloid cells exhibiting markers of cellular senescence and epithelial-mesenchymal transition were identified in SSc-ILD for the first time. In summary, our study utilizes the enriched capabilities of scRNA-seq to identify key divergent cell types and pathways between IPF and SSc-ILD, providing new insights into the shared and distinct mechanisms between idiopathic and autoimmune interstitial lung diseases.

Mechanisms of progressive fibrosis in connective tissue disease (CTD)-associated interstitial lung diseases (ILDs)

Interstitial lung diseases (ILDs), which can arise from a broad spectrum of distinct aetiologies, can manifest as a pulmonary complication of an underlying autoimmune and connective tissue disease (CTD-ILD), such as rheumatoid arthritis-ILD and systemic sclerosis (SSc-ILD). Patients with clinically distinct ILDs, whether CTD-related or not, can exhibit a pattern of common clinical disease behaviour (declining lung function, worsening respiratory symptoms and higher mortality), attributable to progressive fibrosis in the lungs. In recent years, the tyrosine kinase inhibitor nintedanib has demonstrated efficacy and safety in idiopathic pulmonary fibrosis (IPF), SSc-ILD and a broad range of other fibrosing ILDs with a progressive phenotype, including those associated with CTDs. Data from phase II studies also suggest that pirfenidone, which has a different-yet largely unknown-mechanism of action, may also have activity in other fibrosing ILDs with a progressive phenotype, in addition to its known efficacy in IPF. Collectively, these studies add weight to the hypothesis that, irrespective of the original clinical diagnosis of ILD, a progressive fibrosing phenotype may arise from common, underlying pathophysiological mechanisms of fibrosis involving pathways associated with the targets of nintedanib and, potentially, pirfenidone. However, despite the early proof of concept provided by these clinical studies, very little is known about the mechanistic commonalities and differences between ILDs with a progressive phenotype. In this review, we explore the biological and genetic mechanisms that drive fibrosis, and identify the missing evidence needed to provide the rationale for further studies that use the progressive phenotype as a target population.

Economic Burden and Management of Systemic Sclerosis-Associated Interstitial Lung Disease in 8 European Countries: The BUILDup Delphi Consensus Study

INTRODUCTION

Systemic sclerosis (SSc) is a rare chronic autoimmune disease characterised by microvascular damage, immune dysregulation and fibrosis, affecting the skin, joints and internal organs. Interstitial lung disease (ILD) is frequently associated with systemic sclerosis (SSc-ILD), leading to a poor prognosis and a high mortality rate. The aim of the BUILDup study (BUrden of Interstitial Lung Disease Consensus Panel) was to investigate the overall disease management and to estimate the social and economic burden of SSc-ILD across 8 European countries.

METHODS

A modified Delphi method was used to obtain information on the management of SSc-ILD patients among 40 specialists (panellists) from 8 European countries. Average annual costs per patient and country were estimated by means of a direct cost-analysis study.

RESULTS

The panellists had managed 805 SSc-ILD patients in the last year, 39.1% with limited (L-SSc-ILD) and 60.9% with extensive (E-SSc-ILD) disease. Of these, 32.8% of the panellists started treatment at diagnosis, 42.3% after signs of deterioration/progression and 24.7% when the disease had become extensive. The average annual cost of SSc-ILD per patient ranged from €6191 in Greece to €25,354 in Sweden. Main cost drivers were follow-up procedures, accounting for 80% of the total annual costs. Hospitalisations were the most important cost driver of follow-up costs. Healthcare resource use was more important for E-SSc-ILD compared to L-SSc-ILD. Early retirement was taken by 40.4% of the patients with an average of 11.9 years before the statutory retirement age.

CONCLUSIONS

SSc-ILD entails not only a clinical but also a social and economic burden, and is higher for E-SSc-ILD.