Idiopathic Pulmonary Fibrosis: Prospective, Case-Controlled Study of Natural History and Circulating Biomarkers

The fibroblast activation protein alpha as a biomarker of pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a rare, chronic, and progressive interstitial lung disease with an average survival of approximately 3 years. The evolution of IPF is unpredictable, with some patients presenting a relatively stable condition with limited progression over time, whereas others deteriorate rapidly. In addition to IPF, other interstitial lung diseases can lead to pulmonary fibrosis, and up to a third have a progressive phenotype with the same prognosis as IPF. Clinical, biological, and radiological risk factors of progression were identified, but no specific biomarkers of fibrogenesis are currently available. A recent interest in the fibroblast activation protein alpha (FAPα) has emerged. FAPα is a transmembrane serine protease with extracellular activity. It can also be found in a soluble form, also named anti-plasmin cleaving enzyme (APCE). FAPα is specifically expressed by activated fibroblasts, and quinoline-based specific inhibitors (FAPI) were developed, allowing us to visualize its distribution in vivo by imaging techniques. In this review, we discuss the use of FAPα as a useful biomarker for the progression of lung fibrosis, by both its assessment in human fluids and/or its detection by imaging techniques and immunohistochemistry.

High resolution computed tomography in systemic sclerosis: From diagnosis to follow-up

Early diagnosis of interstitial lung disease (ILD) and pulmonary hypertension (PH) is crucial in systemic sclerosis (SSc) for both management and treatment. However, diagnosing SSc-ILD can be challenging because symptoms of lung involvement are often non-specific at the early stages of disease. High-resolution computed tomography (HRCT) of the chest is recognized as the most accurate imaging modality for baseline and follow-up evaluation of SSc-ILD. Key features of SSc-ILD on HRCT include a non-specific interstitial pneumonia (NSIP) pattern, with peripheral ground-glass opacities and extensive traction bronchiectasis. Less common HRCT manifestations include usual interstitial pneumonia (UIP) pattern, followed by diffuse alveolar damage (DAD), diffuse alveolar hemorrhage (DAH) and organizing pneumonia (OP). The extent of disease on HRCT is known to relate with prognosis and serial assessments can be helpful in monitoring disease progression or treatment response. We discuss the main chest computed tomography (CT) manifestations of SSc, highlighting the role of imaging at both baseline and follow-up evaluations.

Molecular Endotypes of Idiopathic Pulmonary Fibrosis: A Latent Class Analysis of Two Multicenter Observational Cohorts

Rationale: Idiopathic pulmonary fibrosis (IPF) causes irreversible fibrosis of the lung parenchyma. Although antifibrotic therapy can slow IPF progression, treatment response is variable. There exists a critical need to develop a precision medicine approach to IPF. Objectives: To identify and validate biologically driven molecular endotypes of IPF. Methods: Latent class analysis (LCA) was independently performed in prospectively recruited discovery (n = 875) and validation (n = 347) cohorts. Twenty-five plasma biomarkers associated with fibrogenesis served as class-defining variables. The association between molecular endotype and 4-year transplant-free survival was tested using multivariable Cox regression adjusted for baseline confounders. Endotype-dependent differential treatment response to future antifibrotic exposure was then assessed in a pooled cohort of patients naive to antifibrotic therapy at the time of biomarker measurement (n = 555). Measurements and Main Results: LCA independently identified two latent classes in both cohorts (P < 0.0001). WFDC2 (WAP four-disulfide core domain protein 2) was the most important determinant of class membership across cohorts. Membership in class 2 was characterized by higher biomarker concentrations and a higher risk of death or transplant (discovery, hazard ratio [HR], 2.02; 95% confidence interval [CI], 1.64-2.48; P < 0.001; validation, HR, 1.95; 95% CI, 1.34-2.82; P < 0.001). In pooled analysis, significant heterogeneity in treatment effect was observed between endotypes (P = 0.030 for interaction), with a favorable antifibrotic response in class 2 (HR, 0.64; 95% CI, 0.45-0.93; P = 0.018) but not in class 1 (HR, 1.19; 95% CI, 0.77-1.84; P = 0.422). Conclusions: In this multicohort study, we identified two novel molecular endotypes of IPF with divergent clinical outcomes and responses to antifibrotic therapy. Pending further validation, these endotypes could enable a precision medicine approach for future IPF clinical trials.

Effect of human epididymis protein 4 on hyperoxia-induced bronchial dysplasia in newborn rats

OBJECTIVE

The study aimed to elucidate the role and the underlying mechanism of human epididymis protein 4 (HE4) in the pathogenesis of hyperoxia-induced bronchial dysplasia in newborn rats.

METHODS

Forty neonatal Sprague-Dawley (SD) rats were separated into two groups: a normal control group (20.8% oxygen concentration) and a hyperoxia-induced group (85% oxygen concentration). Three time intervals of 24 h, 3 days and 7 days were chosen for each group. Haematoxylin-eosin staining was used to identify the pathological alterations in the lung tissue of the SD rats. Enzyme-linked immunosorbent assay was used to evaluate plasma protein levels. Real-time reverse transcription polymerase chain reaction was used to determine messenger RNA (mRNA) expression.

RESULTS

In newborn SD rats, hyperoxia intervention within 7 days may result in acute lung damage. In the plasma and tissue of newborn SD rats, hyperoxia induction may raise levels of HE4, matrix metalloproteinases (MMP) 9 and tissue inhibitors of metalloproteinases (TIMP) 1. We discovered that the HE4 protein activates the phosphorylation of extracellular regulated protein kinases (ERK) and p65, activates the downstream MMP9 signalling pathway, inhibits MMP9 mRNA expression, inhibits protein activity, reduces type I collagen degradation, increases collagen secretion and promotes matrix remodelling and fibrosis in neonatal rat primary alveolar type II epithelial cells by overexpressing and silencing the HE4 gene.

CONCLUSION

Through the ERK, MMP9 and TIMP1 signalling pathways, HE4 mediates the pathophysiological process of hyperoxia-induced lung damage in rats. Lung damage and lung basal remodelling are mediated by HE4 overexpression.

Predictive biomarkers of disease progression in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial disease that cannot be cured, and treatment options for IPF are very limited. Early diagnosis, close monitoring of disease progression, and timely treatment are therefore the best options for patients due to the irreversibility of IPF. Effective markers help doctors judge the development and prognosis of disease. Recent research on traditional biomarkers (KL-6, SP-D, MMP-7, TIMPs, CCL18) has provided novel ideas for predicting disease progression and prognosis. Some emerging biomarkers (HE4, GDF15, PRDX4, inflammatory cells, G-CSF) also provide more possibilities for disease prediction. In addition to markers in serum and bronchoalveolar lavage fluid (BALF), some improvements related to the GAP model and chest HRCT also show good predictive ability for disease prognosis.

Lung functional imaging

Pulmonary functional imaging modalities such as computed tomography, magnetic resonance imaging and nuclear imaging can quantitatively assess regional lung functional parameters and their distributions. These include ventilation, perfusion, gas exchange at the microvascular level and biomechanical properties, among other variables. This review describes the rationale, strengths and limitations of the various imaging modalities employed for lung functional imaging. It also aims to explain some of the most commonly measured parameters of regional lung function. A brief review of evidence on the role and utility of lung functional imaging in early diagnosis, accurate lung functional characterisation, disease phenotyping and advancing the understanding of disease mechanisms in major respiratory disorders is provided.

Potential biomarkers for diagnosis and disease evaluation of idiopathic pulmonary fibrosis

ABSTRACT

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease characterized by progressive lung fibrogenesis and histological features of usual interstitial pneumonia. IPF has a poor prognosis and presents a spectrum of disease courses ranging from slow evolving disease to rapid deterioration; thus, a differential diagnosis remains challenging. Several biomarkers have been identified to achieve a differential diagnosis; however, comprehensive reviews are lacking. This review summarizes over 100 biomarkers which can be divided into six categories according to their functions: differentially expressed biomarkers in the IPF compared to healthy controls; biomarkers distinguishing IPF from other types of interstitial lung disease; biomarkers differentiating acute exacerbation of IPF from stable disease; biomarkers predicting disease progression; biomarkers related to disease severity; and biomarkers related to treatment. Specimen used for the diagnosis of IPF included serum, bronchoalveolar lavage fluid, lung tissue, and sputum. IPF-specific biomarkers are of great clinical value for the differential diagnosis of IPF. Currently, the physiological measurements used to evaluate the occurrence of acute exacerbation, disease progression, and disease severity have limitations. Combining physiological measurements with biomarkers may increase the accuracy and sensitivity of diagnosis and disease evaluation of IPF. Most biomarkers described in this review are not routinely used in clinical practice. Future large-scale multicenter studies are required to design and validate suitable biomarker panels that have diagnostic utility for IPF.

CC Chemokines in Idiopathic Pulmonary Fibrosis: Pathogenic Role and Therapeutic Potential

Idiopathic pulmonary fibrosis (IPF), characterized by progressive worsening of dyspnea and irreversible decline in lung function, is a chronic and progressive respiratory disease with a poor prognosis. Chronic or repeated lung injury results in inflammation and an excessive injury-repairing response that drives the development of IPF. A number of studies have shown that the development and progression of IPF are associated with dysregulated expression of several chemokines and chemokine receptors, several of which have been used as predictors of IPF outcome. Chemokines of the CC family play significant roles in exacerbating IPF progression by immune cell attraction or fibroblast activation. Modulating levels of detrimental CC chemokines and interrupting the corresponding transduction axis by neutralizing antibodies or antagonists are potential treatment options for IPF. Here, we review the roles of different CC chemokines in the pathogenesis of IPF, and their potential use as biomarkers or therapeutic targets.

Identification of immune biomarkers associated with basement membranes in idiopathic pulmonary fibrosis and their pan-cancer analysis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive interstitial lung disease of unknown etiology, characterized by diffuse alveolitis and alveolar structural damage. Due to the short median survival time and poor prognosis of IPF, it is particularly urgent to find new IPF biomarkers. Previous studies have shown that basement membranes (BMs) are associated with the development of IPF and tumor metastasis. However, there is still a lack of research on BMs-related genes in IPF. Therefore, we investigated the expression level of BMs genes in IPF and control groups, and explored their potential as biomarkers for IPF diagnosis. In this study, the GSE32537 and GSE53845 datasets were used as training sets, while the GSE24206, GSE10667 and GSE101286 datasets were used as validation sets. In the training set, seven immune biomarkers related to BMs were selected by differential expression analysis, machine learning algorithm (LASSO, SVM-RFE, Randomforest) and ssGSEA analysis. Further ROC analysis confirmed that seven BMs-related genes played an important role in IPF. Finally, four immune-related Hub genes (COL14A1, COL17A1, ITGA10, MMP7) were screened out. Then we created a logistic regression model of immune-related hub genes (IHGs) and used a nomogram to predict IPF risk. The nomogram model was evaluated to have good reliability and validity, and ROC analysis showed that the AUC value of IHGs was 0.941 in the training set and 0.917 in the validation set. Pan-cancer analysis showed that IHGs were associated with prognosis, immune cell infiltration, TME, and drug sensitivity in 33 cancers, suggesting that IHGs may be potential targets for intervention in human diseases including IPF and cancer.

The Role of Serum 1,25-Dihydroxy Vitamin D3 and PCT in Idiopathic Pulmonary Fibrosis

OBJECTIVE

Biomarkers for the acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) are urgently needed to provide better patient management. We aimed to investigate whether serum 1,25(OH)2D3 (1,25-dihydroxy vitamin D3) levels predict AE-IPF and whether they could be a potential prognostic biomarker for IPF.

PARTICIPANTS AND METHODS

This prospective study included 72 patients with IPF (31 with stable IPF and 41 with AE-IPF). All participants were recruited during hospitalisation at Tianjin Chest Hospital and were followed up for at least 12 months. Demographics, comorbidities, arterial blood gas, and serum biochemical profile, radiological features, and anti-fibrotic therapy were evaluated. Serum concentrations of 1,25(OH)2D3 and transforming growth factor beta1 (TGFβ1) were detected using enzyme-linked immunosorbent assay (ELISA). Risk factors for AE-IPF were identified using multivariate analysis. Prognostic factors were assessed using Kaplan-Meier and Cox regression analyses.

RESULTS

Baseline values of alveolar-arterial oxygen difference (A-aDO2) (40.85 mmHg vs 29.2 mmHg, p =0.035), white blood cell counts (10.09 ± 4.2×109/L vs 7.46 ± 7.84×109/L, p <0.001), percentage of monocytes (7.36 ± 1.36% vs 6.6 ± 1.2%, p =0.017), C-reactive protein (CRP) (2.1 mg/dL vs 1.12 mg/dL, p =0.015) and procalcitonin (PCT) (36.59% vs 3.23%, p <0.001) were significantly higher in AE-IPF patients than in stable IPF patients. Instead, the mean concentration of serum calcium and 1,25(OH)2D3 at baseline were higher in IPF patients with stable disease than in those with acute exacerbation (2.17 ± 0.13 nmol/L vs 2.09 ± 0.13 nmol/L, p =0.023 and 16.62 pg/mL vs 11.58 pg/mL, p <0.001, respectively). In multivariate analysis, a higher proportion of patients with lower serum 1,25(OH)2D3 levels experienced AE-IPF (OR 0.884, 95% CI 0.791-0.987, p =0.029), and rising serum PCT level (PCT > 0.05 ng/mL) was associated with an increased risk of mortality (HR 3.664, 95% CI 1.010-12.900, p =0.043).

CONCLUSION

Decreased serum 1,25(OH)2D3 is associated with an increased risk of acute exacerbation for patients with IPF. A high serum PCT level is predictive of worse prognosis in IPF patients. 1,25(OH)2D3 may be a potential biomarker for AE-IPF, while PCT could be a prognostic biomarker for IPF.

Plasma prostasin: a novel risk marker for incidence of diabetes and cancer mortality

AIMS/HYPOTHESIS

Diabetes is associated with an increased risk of cancer. Prostasin is an epithelial sodium channel stimulator that has been associated with suppression of tumours, glucose metabolism and hyperglycaemia-associated tumour pathology. However, the association between prostasin, diabetes and cancer mortality has not been well investigated in humans. We aim to investigate the associations between plasma prostasin and diabetes, and to explore whether prostasin has an effect on cancer mortality risk in individuals with hyperglycaemia.

METHODS

Plasma prostasin was measured using samples from the Malmö Diet and Cancer Study Cardiovascular Cohort, and statistical analysis was performed from both sex-specific quartiles and per 1 SD. The cross-sectional association between plasma prostasin and diabetes was first studied in 4658 participants (age 57.5 ± 5.9 years, 39.9% men). After excluding 361 with prevalent diabetes, the associations of prostasin with incident diabetes and cancer mortality risk were assessed using Cox regression analysis. The interactions between prostasin and blood glucose levels as well as other covariates were tested.

RESULTS

The adjusted OR for prevalent diabetes in the 4th vs 1st quartile of prostasin concentrations was 1.95 (95% CI 1.39, 2.76) (p for trend <0.0001). During mean follow-up periods of 21.9 ± 7.0 and 23.5 ± 6.1 years, respectively, 702 participants developed diabetes and 651 died from cancer. Prostasin was significantly associated with the incidence of diabetes. The adjusted HR for diabetes in the 4th vs 1st quartile of prostasin concentrations was 1.76 (95% CI 1.41, 2.19) (p for trend <0.0001). Prostasin was also associated with cancer mortality There was a significant interaction between prostasin and fasting blood glucose for cancer mortality risk (p for interaction =0.022), with a stronger association observed in individuals with impaired fasting blood glucose levels at baseline (HR per 1 SD change 1.52; 95% CI 1.07, 2.16; p=0.019).

CONCLUSIONS/INTERPRETATION

Plasma prostasin levels are positively associated with diabetes risk and with cancer mortality risk, especially in individuals with high blood glucose levels, which may shed new light on the relationship between diabetes and cancer.

The Proteomic Profile of Interstitial Lung Abnormalities

Rationale: Knowledge on biomarkers of interstitial lung disease is incomplete. Interstitial lung abnormalities (ILAs) are radiologic changes that may present in its early stages. Objectives: To uncover blood proteins associated with ILAs using large-scale proteomics methods. Methods: Data from two prospective cohort studies, the AGES-Reykjavik (Age, Gene/Environment Susceptibility-Reykjavik) study (N = 5,259) for biomarker discovery and the COPDGene (Genetic Epidemiology of COPD) study (N = 4,899) for replication, were used. Blood proteins were measured using DNA aptamers, targeting more than 4,700 protein analytes. The association of proteins with ILAs and ILA progression was assessed with regression modeling, as were associations with genetic risk factors. Adaptive Least Absolute Shrinkage and Selection Operator models were applied to bootstrap data samples to discover sets of proteins predictive of ILAs and their progression. Measurements and Main Results: Of 287 associations, SFTPB (surfactant protein B) (odds ratio [OR], 3.71 [95% confidence interval (CI), 3.20-4.30]; P = 4.28 × 10^-67), SCGB3A1 (Secretoglobin family 3A member 1) (OR, 2.43 [95% CI, 2.13-2.77]; P = 8.01 × 10^-40), and WFDC2 (WAP four-disulfide core domain protein 2) (OR, 2.42 [95% CI, 2.11-2.78]; P = 4.01 × 10^-36) were most significantly associated with ILA in AGES-Reykjavik and were replicated in COPDGene. In AGES-Reykjavik, concentrations of SFTPB were associated with the rs35705950 MUC5B (mucin 5B) promoter polymorphism, and SFTPB and WFDC2 had the strongest associations with ILA progression. Multivariate models of ILAs in AGES-Reykjavik, ILAs in COPDGene, and ILA progression in AGES-Reykjavik had validated areas under the receiver operating characteristic curve of 0.880, 0.826, and 0.824, respectively. Conclusions: Novel, replicated associations of ILA, its progression, and genetic risk factors with numerous blood proteins are demonstrated as well as machine-learning-based models with favorable predictive potential. Several proteins are revealed as potential markers of early fibrotic lung disease.

Human epididymis protein 4 aggravates airway inflammation and remodeling in chronic obstructive pulmonary disease

Background

Chronic obstructive pulmonary disease (COPD) is a progressive disease characterized by chronic inflammation and airway remodeling. Human epididymis protein 4 (HE4) plays a critical role in various inflammatory or fibrotic diseases. However, the role of HE4 in COPD remains unidentified.

Methods

HE4 expression was determined in the lung tissues from COPD patients and cigarette smoke (CS)-exposed mice using immunohistochemical staining, qPCR, or western blot. The plasma level of HE4 was detected by ELISA. The regulations of HE4 in the expressions of CS extract (CSE)-induced inflammatory cytokines in human bronchial epithelial cells (HBE) were investigated through knockdown or overexpression of HE4. The role of secretory HE4 (sHE4) in the differentiation and proliferation in human pulmonary fibroblast cells (HPF) was explored via qPCR, western blot, CCK8 assay or 5-ethynyl-2′-deoxyuridine (EdU) staining. The probe of related mechanism in CSE-induced HE4 increase in HBE was conducted by administrating N-acetylcysteine (NAC).

Results

HE4 was up-regulated in both the lung tissue and plasma of COPD patients relative to controls, and the plasma HE4 was negatively associated with lung function in COPD patients. The same enhanced HE4 expression was verified in CS-exposed mice and CSE-induced HBE, but CSE failed to increase HE4 expression in HPF. In vitro experiments showed that reducing HE4 expression in HBE alleviated CSE-induced IL-6 release while overexpressing HE4 facilitated IL-6 expression, mechanistically through affecting phosphorylation of NFκB-p65, whereas intervening HE4 expression had no distinctive influence on IL-8 secretion. Furthermore, we confirmed that sHE4 promoted fibroblast-myofibroblast transition, as indicated by promoting the expression of fibronectin, collagen I and α-SMA via phosphorylation of Smad2. EdU staining and CCK-8 assay demonstrated the pro-proliferative role of sHE4 in HPF, which was further confirmed by enhanced expression of survivin and PCNA. Pretreatment of NAC in CSE or H₂O₂-induced HBE mitigated HE4 expression.

Conclusions

Our study indicates that HE4 may participate in airway inflammation and remodeling of COPD. Cigarette smoke enhances HE4 expression and secretion in bronchial epithelium mediated by oxidative stress. Increased HE4 promotes IL-6 release in HBE via phosphorylation of NFκB-p65, and sHE4 promotes fibroblastic differentiation and proliferation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02040-7.

A systematic review of blood biomarkers with individual participant data meta-analysis of matrix metalloproteinase-7 in idiopathic pulmonary fibrosis

BACKGROUND

Blood-derived biomarkers have been described extensively as potential prognostic markers in idiopathic pulmonary fibrosis (IPF), but studies have been limited by analyses using data-dependent thresholds, inconsistent adjustment for confounders and an array of end-points, thus often yielding ungeneralisable results. Meta-analysis of individual participant data (IPD) is a powerful tool to overcome these limitations. Through systematic review of blood-derived biomarkers, sufficient studies with measurements of matrix metalloproteinase (MMP)-7 were identified to facilitate standardised analyses of the prognostic potential of this biomarker in IPF.

METHODS

Electronic databases were searched on 12 November 2020 to identify prospective studies reporting outcomes in patients with untreated IPF, stratified according to at least one pre-specified biomarker, measured at either baseline, or change over 3 months. IPD were sought for studies investigating MMP-7 as a prognostic factor. The primary outcome was overall mortality according to standardised MMP-7 z-scores, with a secondary outcome of disease progression in 12 months, all adjusted for age, gender, smoking and baseline forced vital capacity.

RESULTS

IPD was available for nine studies out of 12 identified, reporting outcomes from 1664 participants. Baseline MMP-7 levels were associated with increased mortality risk (adjusted hazard ratio 1.23, 95% CI 1.03-1.48; I2=64.3%) and disease progression (adjusted OR 1.27, 95% CI 1.11-1.46; I2=5.9%). In limited studies, 3-month change in MMP-7 was not associated with outcomes.

CONCLUSION

IPD meta-analysis demonstrated that greater baseline MMP-7 levels were independently associated with an increased risk of poor outcomes in patients with untreated IPF, while short-term changes did not reflect disease progression.

Quantitative proteomic analysis of bronchoalveolar lavage fluid in West Highland white terriers with canine idiopathic pulmonary fibrosis

Background

Canine idiopathic pulmonary fibrosis (CIPF) is a chronic, progressive, interstitial fibrosing lung disease, manifesting as cough, exercise intolerance and ultimately, dyspnea and respiratory failure. It mainly affects West Highland white terriers (WHWTs), lacks curable treatment and has a poor prognosis. Aspiration of gastroesophageal refluxate may play a role in the development of CIPF. In the first part of this study, we completed label-free quantitative proteomic analysis of bronchoalveolar lavage fluid (BALF) from CIPF and healthy WHWTs. In the second part, we evaluated potential protein markers of reflux aspiration from canine gastric juice and vomitus and whether these were present in BALF from the two groups.

Results

Across all BALF samples, 417 proteins were identified, and of these, 265 proteins were identified by two or more unique tryptic peptides. Using the 265 high confidence assignments, the quantitative proteome profiles were very similar in the two cohorts, but they could be readily resolved by principal component analysis on the basis of differential protein expression. Of the proteins that were differentially abundant in the two groups, several (including inflammatory and fibrotic markers) were elevated in CIPF, and a smaller, more diverse group of proteins were diminished in CIPF. No protein markers indicative of reflux aspiration were identified.

Conclusions

Label-free proteomics allowed discrimination between CIPF and healthy WHWTs, consistent with fibrotic process but did not provide clear evidence for gastrointestinal aspiration. The measurement of proteins may provide a proteomics signature of CIPF that could be used to evaluate treatment options.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03202-x.

The Prognostic Value of Integrated Analysis of Inflammation and Hypoxia-Related Genes in Idiopathic Pulmonary Fibrosis

Currently, the aetiology and pathogenesis of idiopathic pulmonary fibrosis (IPF) are still largely unclear. Moreover, patients with IPF exhibit a considerable difference in clinical presentation, treatment, and prognosis. Optimal biomarkers or models for IPF prognosis are lacking. Therefore, this study quantified the levels of various hallmarks using a single-sample gene set enrichment analysis algorithm. The hazard ration was calculated using Univariate Cox regression analysis based on the transcriptomic profile of bronchoalveolar lavage cells and clinical survival information. Afterwards, weighted Gene Co-expression Network Analysis was performed to construct a network between gene expression, inflammation response, and hypoxia. Subsequently, univariate Cox, random forest, and multivariate Cox regressions were applied to develop a robust inflammation and hypoxia-related gene signature for predicting clinical outcomes in patients with IPF. Furthermore, a nomogram was constructed to calculate risk assessment. The inflammation response and hypoxia were identified as latent risk factors for patients with IPF. Five genes, including HS3ST1, WFDC2, SPP1, TFPI, and CDC42EP2, were identified that formed the inflammation-hypoxia-related gene signature. Kaplan-Meier plotter showed that the patients with high-risk scores had a worse prognosis than those with low-risk scores in training and validation cohorts. The time-dependent concordance index and the receiver operating characteristic analysis revealed that the risk model could accurately predict the clinical outcome of patients with IPF. Therefore, this study contributes to elucidating the role of inflammation and hypoxia in IPF, which can aid in assessing individual prognosis and personalised treatment decisions.

Consensus document for the selection of lung transplant candidates: An update from the International Society for Heart and Lung Transplantation

Tens of thousands of patients with advanced lung diseases may be eligible to be considered as potential candidates for lung transplant around the world each year. The timing of referral, evaluation, determination of candidacy, and listing of candidates continues to pose challenges and even ethical dilemmas. To address these challenges, the International Society for Heart and Lung Transplantation appointed an international group of members to review the literature, to consider recent advances in the management of advanced lung diseases, and to update prior consensus documents on the selection of lung transplant candidates. The purpose of this updated consensus document is to assist providers throughout the world who are caring for patients with pulmonary disease to identify potential candidates for lung transplant, to optimize the timing of the referral of these patients to lung transplant centers, and to provide transplant centers with a framework for evaluating and selecting candidates. In addition to addressing general considerations and providing disease specific recommendations for referral and listing, this updated consensus document includes an ethical framework, a recognition of the variability in acceptance of risk between transplant centers, and establishes a system to account for how a combination of risk factors may be taken into consideration in candidate selection for lung transplantation.

Screening of Biomarkers Involved in Idiopathic Pulmonary Fibrosis and Regulation of Upstream miRNAs

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is the most common type of fatal interstitial lung disease and IPF patients usually have a poor prognosis. Biomarkers that can predict the occurrence, process and prognosis of IPF will be useful for its diagnosis and treatment. This study aimed to identify the potential biomarkers of IPF and analyze the regulation of upstream miRNAs.

METHODS

The miRNA and gene expression profiles were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) and miRNAs (DEMs) between IPF and normal groups were identified. After co-expression gene pair analysis, functional enrichment analysis was performed. Then, the potential biomarkers of IPF were screened and validated. Finally, the upstream regulatory miRNA of biomarkers was predicted.

RESULTS

A total of 343 DEGs and 21 DEMs were identified between IPF and normal samples. CLDN18, COL6A3, MYRF, PRSS8, RRAS, and SBNO1 were identified as potential IPF biomarkers. In addition, 17 miRNA-target relationship pairs were obtained. The up-regulation of hsa-miR-657, hsa-miR-671-5p, hsa-miR-198, and hsa-miR-940 could regulate the down-regulation of MYRF and the up-regulation of hsa-miR-198 and hsa-miR-373-3p could regulate the down-regulation of RRAS and CLDN18, respectively. Our data indicated that PRSS8, hsa-miR-614, and hsa-miR-503-5p might be involved in the migration and invasion of IPF related cells.

CONCLUSIONS

CLDN18, COL6A3, MYRF, PRSS8, RRAS, and SBNO1 might be potential IPF biomarkers. However, the specific role of these genes and miRNA in IPF needs further experimental research.

Serial Measurements of Circulating KL-6, SP-D, MMP-7, CA19-9, CA-125, CCL18, and Periostin in Patients with Idiopathic Pulmonary Fibrosis Receiving Antifibrotic Therapy: An Exploratory Study

Idiopathic pulmonary fibrosis (IPF) is a progressive and inevitably fatal disease with a heterogeneous clinical course. This study aimed to evaluate the usefulness of circulating biomarkers in routine IPF clinical practice. We conducted an exploratory study in a cohort of 28 IPF subjects qualified for anti-fibrotic therapy with up to 24 months serial measurements of seven IPF biomarkers, including those that are well-established, Krebs von den Lungen-6 (KL-6), surfactant protein D (SP-D), matrix metalloproteinase 7 (MMP-7), and more recently introduced ones, cancer antigen 19-9 (CA19-9), cancer antigen 125 (CA-125), chemokine (C-C motif) ligand 18 (CCL18), and periostin. Among studied biomarkers, SP-D had the highest diagnostic accuracy to differentiate IPF subjects from controls, followed by MMP-7 and KL-6. At each study timepoint, KL-6 levels correlated inversely with forced vital capacity % predicted (FVC% pred.), and transfer factor of the lung for carbon monoxide % predicted (T_L,CO% pred.), while SP-D levels correlated inversely with FVC% pred. and T_L,CO% pred. at 24 months of anti-fibrotic therapy. Baseline KL-6 and CA19-9 concentrations were significantly elevated in patients with progressive disease in comparison to patients with stable disease. In addition, in the progressors subgroup CA19-9 concentrations significantly increased over the second year of study follow-up. In patients with progressive disease, we observed a significant inverse correlation between a change in SP-D levels and a change in FVC% pred. in the first year of treatment, whereas in the second year a significant inverse correlation between a change in KL-6 levels and a change in FVC% pred. was noted. Our study findings support the view that both well-established IPF biomarkers, including KL-6, SP-D, and MMP-7, and more recently introduced ones, like CA19-9, have the potential to support clinical practice in IPF.

Identification and Validation of Potential Biomarkers and Pathways for Idiopathic Pulmonary Fibrosis by Comprehensive Bioinformatics Analysis

Objective

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, irreversible, high-mortality lung disease, but its pathogenesis is still unclear. Our purpose was to explore potential genes and molecular mechanisms underlying IPF.

Methods

IPF-related data were obtained from the GSE99621 dataset. Differentially expressed genes (DEGs) were identified between IPF and controls. Their biological functions were analyzed. The relationships between DEGs and microRNAs (miRNAs) were predicted. DEGs and pathways were validated in a microarray dataset. A protein-protein interaction (PPI) network was constructed based on these common DEGs. Western blot was used to validate hub genes in IPF cell models by western blot.

Results

DEGs were identified for IPF than controls in the RNA-seq dataset. Functional enrichment analysis showed that these DEGs were mainly enriched in immune and inflammatory response, chemokine-mediated signaling pathway, cell adhesion, and other biological processes. In the miRNA-target network based on RNA-seq dataset, we found several miRNA targets among all DEGs, like RAB11FIP1, TGFBR3, and SPP1. We identified 304 upregulated genes and 282 downregulated genes in IPF compared to controls both in the microarray and RNA-seq datasets. These common DEGs were mainly involved in cell adhesion, extracellular matrix organization, oxidation-reduction process, and lung vasculature development. In the PPI network, 3 upregulated and 4 downregulated genes could be considered hub genes, which were confirmed in the IPF cell models.

Conclusion

Our study identified several IPF-related DEGs that could become potential biomarkers for IPF. Large-scale multicentric studies are eagerly needed to confirm the utility of these biomarkers.

Monocyte Count as a Prognostic Biomarker in Patients with Idiopathic Pulmonary Fibrosis

Rationale: There is an urgent need for simple, cost-effective prognostic biomarkers for idiopathic pulmonary fibrosis (IPF); biomarkers that show potential include monocyte count. Objectives: We used pooled data from pirfenidone and IFNγ-1b trials to explore the association between monocyte count and prognosis in patients with IPF. Methods: This retrospective pooled analysis included patients (active and placebo arms) from the following four phase III, randomized, placebo-controlled trials: ASCEND (NCT01366209), CAPACITY (NCT00287729 and NCT00287716), and INSPIRE (NCT00075998). Outcomes included IPF progression (≥10% absolute decline in FVC% predicted, ≥50 m decline in 6-minute-walk distance, or death), all-cause hospitalization, and all-cause mortality over 1 year. The relationship between monocyte count (defined as time-dependent) and outcomes was assessed using bivariate and multivariable models. Measurements and Main Results: This analysis included 2,067 patients stratified by monocyte count (at baseline: <0.60 × 109 cells/L [n = 1,609], 0.60 to <0.95 × 109 cells/L [n = 408], and ≥0.95 × 109 cells/L [n = 50]). In adjusted analyses, a higher proportion of patients with monocyte counts of 0.60 to <0.95 × 109 cells/L or ≥0.95 × 109 cells/L versus <0.60 × 109 cells/L experienced IPF progression (P = 0.016 and P = 0.002, respectively), all-cause hospitalization (P = 0.030 and P = 0.003, respectively), and all-cause mortality (P = 0.005 and P < 0.001, respectively) over 1 year. Change in monocyte count from baseline was not associated with any of the outcomes over 1 year and did not appear to be affected by study treatment. Conclusions: In patients with IPF, elevated monocyte count was associated with increased risks of IPF progression, hospitalization, and mortality. Monocyte count may provide a simple and inexpensive prognostic biomarker in IPF.

Biomarkers in Progressive Fibrosing Interstitial Lung Disease: Optimizing Diagnosis, Prognosis, and Treatment Response

Interstitial lung disease (ILD) comprises a heterogenous group of diffuse lung disorders that commonly result in irreversible pulmonary fibrosis. While idiopathic pulmonary fibrosis (IPF) is the prototypical progressive fibrosing ILD (PF-ILD), a high proportion of patients with other ILD subtypes develop a PF-ILD phenotype. Evidence exists for shared pathobiology leading to progressive fibrosis, suggesting that biomarkers of disease activity may prove informative across the wide spectrum of ILDs. Biomarker investigation to date has identified a number of molecular markers that predict relevant ILD endpoints, including disease presence, prognosis, and/or treatment response. In this review, we provide an overview of potentially informative biomarkers in patients with ILD, including those suggestive of a PF-ILD phenotype. We highlight the recent genomic, transcriptomic, and proteomic investigations that identified these biomarkers and discuss the body compartments in which they are found, including the peripheral blood, airway, and lung parenchyma. Finally, we identify critical gaps in knowledge within the field of ILD biomarker research and propose steps to advance the field toward biomarker implementation.

Increased monocyte count and red cell distribution width as prognostic biomarkers in patients with Idiopathic Pulmonary Fibrosis

Background

Idiopathic Pulmonary Fibrosis (IPF) represents a chronic lung disease with unpredictable course.

Methods

We aimed to investigate prognostic performance of complete blood count parameters in IPF. Treatment-naïve patients with IPF were retrospectively enrolled from two independent cohorts (derivation and validation) and split into subgroups (high and low) based on median baseline monocyte count and red cell distribution width (RDW).

Results

Overall, 489 patients (derivation cohort: 300, validation cohort: 189) were analyzed. In the derivation cohort, patients with monocyte count ≥ 0.60 K/μL had significantly lower median FVC%pred [75.0, (95% CI 71.3–76.7) vs. 80.9, (95% CI 77.5–83.1), (P = 0.01)] and DLCO%pred [47.5, (95% CI 44.3–52.3) vs. 53.0, (95% CI 48.0–56.7), (P = 0.02)] than patients with monocyte count < 0.60 K/μL. Patients with RDW ≥ 14.1% had significantly lower median FVC%pred [75.5, (95% CI 71.2–79.2) vs. 78.3, (95% CI 76.0–81.0), (P = 0.04)] and DLCO%pred [45.4, (95% CI 43.3–50.5) vs. 53.0, (95% CI 50.8–56.8), (P = 0.008)] than patients with RDW < 14.1%. Cut-off thresholds from the derivation cohort were applied to the validation cohort with similar discriminatory value, as indicated by significant differences in median DLCO%pred between patients with high vs. low monocyte count [37.8, (95% CI 35.5–41.1) vs. 45.5, (95% CI 41.9–49.4), (P < 0.001)] and RDW [37.9, (95% CI 33.4–40.7) vs. 44.4, (95% CI 41.5–48.9), (P < 0.001)]. Patients with high monocyte count and RDW of the validation cohort exhibited a trend towards lower median FVC%pred (P = 0.09) and significantly lower median FVC%pred (P = 0.001), respectively. Kaplan–Meier analysis in the derivation cohort demonstrated higher all-cause mortality in patients with high (≥ 0.60 K/μL) vs. low monocyte count (< 0.60 K/μL) [HR 2.05, (95% CI 1.19–3.53), (P = 0.01)].

Conclusions

Increased monocyte count and RDW may represent negative prognostic biomarkers in patients with IPF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01725-9.

Human epididymis protein 4 is a new biomarker to predict the prognosis of progressive fibrosing interstitial lung disease

BACKGROUND

The clinical course and prognosis of progressive fibrosing interstitial lung diseases (PF-ILDs) vary between individuals. Notably, predictive serum biomarkers for disease management are needed. Serum human epididymis protein 4 (HE4) is reportedly elevated in patients with idiopathic pulmonary fibrosis (IPF); however, its clinical utility remains unknown. We evaluated the potential of serum HE4 as a biomarker for patients with PF-ILD.

METHODS

Serum HE4 was measured in a retrospective study consisting of 34 patients with PF-ILD and 40 healthy volunteers. The relationship between serum HE4 levels and clinical parameters or prognosis was investigated. To validate the significance of results obtained, a prospective observational study was performed in 37 patients presenting PF-ILD and 40 control patients without PF-ILD.

RESULTS

Serum HE4 levels were higher in patients with PF-ILD than in healthy volunteers (P < 0.01). Moreover, serum HE4 levels correlated with the extent of honeycombing on chest high-resolution computed tomography (r = 0.41, P = 0.015). In multivariate analysis using the Cox proportional hazard model, higher HE4 levels (>238 pmol/L) were associated with an elevated mortality risk; hazard ratio (HR) 7.27, 95% CI 1.56-34.0, P = 0.01 in the derivation cohort; HR 44.3, 95% CI 4.19-468, P < 0.01 in validation cohort.

CONCLUSIONS

Serum HE4 levels may serve as a new diagnostic and prognostic biomarker for patients with PF-ILD.

Serum surfactant protein D as a predictive biomarker for the efficacy of pirfenidone in patients with idiopathic pulmonary fibrosis: a post-hoc analysis of the phase 3 trial in Japan

Background

Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal disorder with a variable disease course. The recent advancement of antifibrotic therapy has increased the need for reliable and specific biomarkers. This study aimed to assess alveolar epithelial biomarkers as predictors for the efficacy of the antifibrotic drug pirfenidone.

Methods

We conducted a post-hoc analysis of the prospective, multicenter, randomized, placebo-controlled, phase 3 trial of pirfenidone in Japan (total, n = 267; pirfenidone, n = 163; placebo, n = 104). Logistic regression analysis was performed to extract parameters that predicted disease progression, defined by a ≥ 10% relative decline in vital capacity (VC) from baseline and/or death, at week 52. For assessment of serum surfactant protein (SP)-D, SP-A and Krebs von den Lungen (KL)-6, all patients were dichotomized by the median concentration of each biomarker at baseline to the high and low biomarker subgroups. Associations of these concentrations were examined with changes in VC at each time point from baseline up to week 52, along with progression-free survival (PFS). Additionally, the effect of pirfenidone treatment on serial longitudinal concentrations of these biomarkers were evaluated.

Results

In the multivariate logistic regression analysis, body mass index (BMI), %VC and SP-D in the pirfenidone group, and BMI and %VC in the placebo group were indicated as predictors of disease progression. Pirfenidone treatment reduced the decline in VC with statistical significance in the low SP-D and low SP-A subgroups over most of the treatment period, and also prolonged PFS in the low SP-D and low KL-6 subgroups. Furthermore, SP-D levels over time course were reduced in the pirfenidone group from as early as week 8 until the 52-week treatment period compared with the placebo group.

Conclusions

Serum SP-D was the most consistent biomarker for the efficacy of pirfenidone in the cohort trial of IPF. Serial measurements of SP-D might have a potential for application as a pharmacodynamic biomarker.

Trial registration The clinical trial was registered with the Japan Pharmaceutical Information Center (JAPIC) on September 13, 2005 (registration No. JapicCTI-050121; http://Clinicaltrials.jp)

Clinical significance of serum human epididymis protein 4 in liver fibrosis: An experimental study

BACKGROUND

Human epididymis protein 4 (HE4) has been identified as marker for renal fibrosis. Present study aimed to investigate the clinical significance of serum HE4 in liver fibrosis.

METHODS

Serum from 65 liver fibrosis patients, 68 hepatic patients without fibrosis, and 50 controls was collected respectively. Serum HE4 levels were measured by chemiluminescence immunoassay and compared among the groups. The relationships between serum HE4 levels and the clinical characteristics of liver fibrosis were also analyzed. A receiver operator characteristic curve was plotted to investigate the diagnostic efficacy of serum HE4 for liver fibrosis. Child-Pugh (C-P) score and liver fibrosis score were also evaluated. Data were analyzed by statistical software 13.0.

RESULTS

Serum HE4 levels were significantly higher in liver fibrosis than that of controls [105.35 (82.64, 164.18) vs 46.2 (39.9, 58.9) pmol L, P = .00] and hepatic patients without liver fibrosis [105.35 (82.64, 164.18) vs 51.00 (44.02, 65.65) pmol L, P < .01]; Serum HE4 levels in liver fibrosis patients with C-P class C were significantly higher than those with C-P class A [143.75 (106.50, 186.08) vs 81.42 (69.73, 99.26) pmol L, P = .005] and C-P class B [143.75 (106.50, 186.08) vs 113.10 (88.92, 169.50) pmol L, P = .01]; the diagnostic sensitivity and specificity of serum HE4 levels for liver fibrosis detection were 87.5% and 81.1%, at a cutoff value of 69 pmol L; Serum HE4 levels in alcoholic liver fibrosis were higher than that of liver fibrosis with hepatitis B virus infection [131.30 (100.67, 228.35) vs 89.46 (73.74, 116.45) pmol L, P < .01].

CONCLUSION

Serum HE4 was closely correlated with C-P class and might be a potential marker for liver fibrosis.

Molecular approach to the classification of chronic fibrosing lung disease-there and back again

Chronic diffuse parenchymal lung disease (DPLD) is an umbrella term for a very heterogeneous group of lung diseases. Over the last decades, clinical, radiological and histopathological criteria have been established to define and separate these entities. More recently the clinical utility of this approach has been challenged as a unifying concept of pathophysiological mechanisms and a shared response to therapy across the disease spectrum have been described. In this review, we discuss molecular motifs for subtyping and the prediction of prognosis focusing on genetics and markers found in the blood, lavage and tissue. As a purely molecular classification so far lacks sufficient sensitivity and specificity for subtyping, it is not routinely used and not implemented in international guidelines. However, a better molecular characterization of lung disease with a more precise identification of patients with, for example, a risk for rapid disease progression would facilitate more accurate treatment decisions and hopefully contribute to better patients' outcomes.

Therapeutic Effect of Neuraminidase-1-Selective Inhibition in Mouse Models of Bleomycin-Induced Pulmonary Inflammation and Fibrosis

Pulmonary fibrosis remains a serious biomedical problem with no cure and an urgent need for better therapies. Neuraminidases (NEUs), including NEU1, have been recently implicated in the mechanism of pulmonary fibrosis by us and others. We now have tested the ability of a broad-spectrum neuraminidase inhibitor, 2,3-dehydro-2-deoxy-N-acetylneuraminic acid (DANA), to modulate the in vivo response to acute intratracheal bleomycin challenge as an experimental model of pulmonary fibrosis. A marked alleviation of bleomycin-induced body weight loss and notable declines in accumulation of pulmonary lymphocytes and collagen deposition were observed. Real-time polymerase chain reaction analyses of human and mouse lung tissues and primary human lung fibroblast cultures were also performed. A predominant expression and pronounced elevation in the levels of NEU1 mRNA were observed in patients with idiopathic pulmonary fibrosis and bleomycin-challenged mice compared with their corresponding controls, whereas NEU2, NEU3, and NEU4 were expressed at far lower levels. The levels of mRNA for the NEU1 chaperone, protective protein/cathepsin A (PPCA), were also elevated by bleomycin. Western blotting analyses demonstrated bleomycin-induced elevations in protein expression of both NEU1 and PPCA in mouse lungs. Two known selective NEU1 inhibitors, C9-pentyl-amide-DANA (C9-BA-DANA) and C5-hexanamido-C9-acetamido-DANA, dramatically reduced bleomycin-induced loss of body weight, accumulation of pulmonary lymphocytes, and deposition of collagen. Importantly, C9-BA-DANA was therapeutic in the chronic bleomycin exposure model with no toxic effects observed within the experimental timeframe. Moreover, in the acute bleomycin model, C9-BA-DANA attenuated NEU1-mediated desialylation and shedding of the mucin-1 ectodomain. These data indicate that NEU1-selective inhibition offers a potential therapeutic intervention for pulmonary fibrotic diseases. SIGNIFICANCE STATEMENT: Neuraminidase-1-selective therapeutic targeting in the acute and chronic bleomycin models of pulmonary fibrosis reverses pulmonary collagen deposition, accumulation of lymphocytes in the lungs, and the disease-associated loss of body weight-all without observable toxic effects. Such therapy is as efficacious as nonspecific inhibition of all neuraminidases in these models, thus indicating the central role of neuraminidase-1 as well as offering a potential innovative, specifically targeted, and safe approach to treating human patients with a severe malady: pulmonary fibrosis.

CA 19-9 serum levels in patients with end-stage idiopathic pulmonary fibrosis (IPF) and other interstitial lung diseases (ILDs): Correlation with functional decline

Idiopathic pulmonary fibrosis presents a progressive and heterogeneous functional decline. CA 19-9 has been proposed as biomarker to predict disease course, but its role remains unclear. We assessed CA 19-9 levels and clinical data in end-stage ILD patients (48 IPF and 20 non-IPF ILD) evaluated for lung transplant, to correlate these levels with functional decline. Patients were categorized based on their rate of functional decline as slow (n = 20; ΔFVC%pred ≤ 10%/year) or rapid progressors (n = 28; ΔFVC%pred ≥ 10%/year). Nearly half of the entire patients (n = 32; 47%) had CA 19-9 levels ≥37kU/L. CA 19-9 levels in IPF were not different from non-IPF ILD populations, however, the latter group had a median CA 19-9 level above the normal cut-off value of 37 KU/l (60 [17–247] kU/L). Among IPF patients, CA 19-9 was higher in slow than in rapid progressors with a trend toward significance (33vs17kU/L; p = 0.055). In the whole population, CA19-9 levels were inversely related with ΔFVC/year (r = −0.261; p = 0.03), this correlation remained in IPF patients, particularly in rapid progressors (r = −0.51; p = 0.005), but not in non. Moreover, IPF rapid progressors with normal CA 19-9 levels showed the greater ΔFVC/year compared to those with abnormal CA 19-9 (0.95 vs. 0.65 L/year; p = 0.03). In patients with end-stage ILD, CA 19-9 may represent a marker of disease severity, whereas its level is inversely correlated with functional decline, particularly among IPF rapid progressors.

Increased levels of HE4 (WFDC2) in systemic sclerosis: a novel biomarker reflecting interstitial lung disease severity?

Background:

Human epididymis protein 4 (HE4, also known as WFDC-2) has been implicated in fibrotic disorders pathobiology. We tested the hypothesis that HE4 may be used as a candidate biomarker for systemic sclerosis (SSc)-related interstitial lung disease (SSc-ILD).

Methods:

A total of 169 consecutive SSc patients and 169 age-and sex-matched healthy controls were enrolled and blood samples were collected. Pulmonary function tests (PFTs) and paired lavage was performed on 169 patients and 37 healthy controls. All patients were classified as having SSc-no ILD or SSc-ILD, based on high-resolution computed tomography (CT) scans of the chest, and a semiquantitative grade of ILD extent was evaluated through CT scans (grade 1, 0–25%; grade 2, 26–50%; grade 3, 51–75%; grade 4, 76–100%). Serum and bronchoalveolar lavage fluid (BALF) HE4 levels were measured by enzyme-linked immunosorbent assay.

Results:

Serum HE4 levels were higher in SSc patients [median (interquartile range), 139.4 (85.9–181.8) pmol/l] compared with healthy controls [39.5 (24.3–54.2) pmol/l, p < 0.001] and were higher in patients with SSc-ILD [172.1 (94.8–263.3) pmol/l] than in those with SSc-no ILD [97.4 (85.5–156.5) pmol/l, p < 0.001]. This observation was replicated in the BALF samples. Corresponding values were 510.8 (144.6–1013.8) pmol/l for SSc cohort, 754.4 (299–1060) pmol/l for SSc-ILD, 555.1 (203.7–776.2) pmol/l for SSc-no ILD, and 238.7 (97.7–397.6) pmol/l for controls. The semiquantitative grade of ILD on CT scan was significantly proportional to the HE4 levels and the lung function parameter (i.e., FVC) had a negative correlation with the HE4 levels.

Conclusion:

This is the first study to demonstrate the potential clinical utility of blood and BALF HE4 as a biomarker for SSc-ILD. Future prospective validation studies are warranted.

Changes in serum KL-6 levels during short-term strict antigen avoidance are associated with the prognosis of patients with fibrotic hypersensitivity pneumonitis caused by avian antigens

BACKGROUND

Bird-related hypersensitivity pneumonitis (BRHP) is the most common type of fibrotic hypersensitivity pneumonitis (HP). Antigen avoidance (AA) is a key step in the diagnosis and management of HP, but not all fibrotic HP patients improve through AA. Because of the poor prognosis of fibrotic HP, predictive biomarkers to identify patients showing rapid progression during AA are urgently needed.

METHODS

From a retrospective review of the medical records of 1941 patients with interstitial lung disease, 75 cases of fibrotic BRHP confirmed by a provocation test or surgical lung biopsy were identified. To identify potential prognostic markers obtained at or around diagnosis, physiological and serological variables at diagnosis and the relative changes in those variables during strict AA were evaluated. Cox proportional hazards models with log-rank testing were used to compare the associations between these variables and survival.

RESULTS

Univariate analyses showed that gender, smoking status, and the relative change in the serum levels of Krebs von den Lungen-6 (KL-6) were associated with prognosis (P = 0.02, 0.04, and 0.02, respectively), but the presence of honeycombing and the forced vital capacity were not associated with survival. The relative change in KL-6 levels (greater than vs. less than a 10% decrease) was significantly associated with survival in a stratified analysis (73.9 vs. 34.9 months; P = 0.04).

CONCLUSIONS

The relative change in KL-6 levels is associated with the prognosis of patients with fibrotic BRHP independent of previously identified prognostic biomarkers. This finding could help pulmonologists identify fibrotic BRHP patients that are likely to show rapid progression.

Identification of a unique temporal signature in blood and BAL associated with IPF progression

Idiopathic pulmonary fibrosis (IPF) is a progressive and heterogeneous interstitial lung disease of unknown origin with a low survival rate. There are few treatment options available due to the fact that mechanisms underlying disease progression are not well understood, likely because they arise from dysregulation of complex signaling networks spanning multiple tissue compartments. To better characterize these networks, we used systems-focused data-driven modeling approaches to identify cross-tissue compartment (blood and bronchoalveolar lavage) and temporal proteomic signatures that differentiated IPF progressors and non-progressors. Partial least squares discriminant analysis identified a signature of 54 baseline (week 0) blood and lung proteins that differentiated IPF progression status by the end of 80 weeks of follow-up with 100% cross-validation accuracy. Overall we observed heterogeneous protein expression patterns in progressors compared to more homogenous signatures in non-progressors, and found that non-progressors were enriched for proteomic processes involving regulation of the immune/defense response. We also identified a temporal signature of blood proteins that was significantly different at early and late progressor time points (p < 0.0001), but not present in non-progressors. Overall, this approach can be used to generate new hypothesis for mechanisms associated with IPF progression and could readily be translated to other complex and heterogeneous diseases.

Serum CD59: a novel biomarker of idiopathic pulmonary fibrosis?

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is the most common among idiopathic interstitial pneumonia. Life expectancy is estimated around 3-5 years at diagnosis. No reliable prognostic biomarker has been approved for routinary clinical practice of IPF. The aim of this study is to investigate the potential prognostic value of serum CD59 in a cohort of IPF patients.

METHODS

Fifty-seven patients (45 males, 66.1±10 years old) were recruited in Siena Regional Referral Center for Interstitial Lung Disease and underwent serum sampling for CD59 detection during diagnostic pathway. Clinical, functional, radiological and survival data were retrospectively collected. As control group for CD59 values, we recruited eight healthy volunteers (five males, 59.2±18 years old).

RESULTS

CD59 levels were significantly higher in IPF patients in respect with healthy controls (P=0.0238). Patients with CD59 concentrations lower than 15 ng/mL reported a significant reduction of survival time (P=0.009); current or former smokers with CD59 <15 ng/mL showed the worst prognosis (P=0.014).

CONCLUSIONS

CD59 levels were significantly increased in IPF patients, supporting the existence of epithelial damage in the pathogenesis of disease. Lower values of CD59 were associated with a significantly worse prognosis, suggesting a potential role of CD59 in the prognostic estimation of IPF patients.

Diagnostic and Prognostic Biomarkers for Chronic Fibrosing Interstitial Lung Diseases With a Progressive Phenotype

Biomarkers have the potential to become central to the clinical evaluation and monitoring of patients with chronic fibrosing interstitial lung diseases (ILDs) with a progressive phenotype. Here we summarize the current understanding of putative serum, BAL fluid, and genetic biomarkers in this setting, according to their hypothesized pathobiologic mechanisms: evidence of epithelial cell dysfunction (eg, Krebs von den Lungen-6 antigen), fibroblast proliferation and extracellular matrix production or turnover (eg, matrix metalloproteinase-1), or immune dysregulation (eg, CC chemokine ligand 18). While most of the available data come from idiopathic pulmonary fibrosis (IPF), the prototypic progressive fibrosing ILD, data are available in the broader patient population of chronic fibrosing ILDs. A number of these biomarkers show promise, however, none have been validated. In this review article, we assess both the status of proposed biomarkers for chronic fibrosing lung diseases with a progressive phenotype in predicting disease risk or predisposition, diagnosis, prognosis, and treatment response and provide a direct comparison between IPF and other chronic fibrotic ILDs. We also reflect on the current clinical usefulness and future direction of research for biomarkers in the setting of chronic fibrosing ILDs with a progressive phenotype.

Circulating matrix metalloproteinases and tissue metalloproteinase inhibitors in patients with idiopathic pulmonary fibrosis in the multicenter IPF-PRO Registry cohort

Background

Matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) play important roles in the turnover of extracellular matrix and in the pathogenesis of idiopathic pulmonary fibrosis (IPF). This study aimed to determine the utility of circulating MMPs and TIMPs in distinguishing patients with IPF from controls and to explore associations between MMPs/TIMPs and measures of disease severity in patients with IPF.

Methods

The IPF cohort (n = 300) came from the IPF-PRO Registry, an observational multicenter registry of patients with IPF that was diagnosed or confirmed at the enrolling center in the past 6 months. Controls (n = 100) without known lung disease came from a population-based registry. Generalized linear models were used to compare circulating concentrations of MMPs 1, 2, 3, 7, 8, 9, 12, and 13 and TIMPs 1, 2, and 4 between patients with IPF and controls, and to investigate associations between circulating levels of these proteins and measures of IPF severity. Multivariable models were fit to identify the MMP/TIMPs that best distinguished patients with IPF from controls.

Results

All the MMP/TIMPs analyzed were present at significantly higher levels in patients with IPF compared with controls except for TIMP2. Multivariable analyses selected MMP8, MMP9 and TIMP1 as top candidates for distinguishing patients with IPF from controls. Higher concentrations of MMP7, MMP12, MMP13 and TIMP4 were significantly associated with lower diffusion capacity of the lung for carbon monoxide (DL_CO) % predicted and higher composite physiologic index (worse disease). MMP9 was associated with the composite physiologic index. No MMP/TIMPs were associated with forced vital capacity % predicted.

Conclusions

Circulating MMPs and TIMPs were broadly elevated among patients with IPF. Select MMP/TIMPs strongly associated with measures of disease severity. Our results identify potential MMP/TIMP targets for further development as disease-related biomarkers.

Comparative Profiling of Serum Protein Biomarkers in Rheumatoid Arthritis-Associated Interstitial Lung Disease and Idiopathic Pulmonary Fibrosis

OBJECTIVE

Interstitial lung disease (ILD) is a frequent complication of rheumatoid arthritis (RA), occurring in up to 40% of patients during the course of their disease. Early diagnosis is critical, particularly given the shared clinicoepidemiologic features between advanced rheumatoid arthritis-associated ILD (RA-ILD) and idiopathic pulmonary fibrosis (IPF). This study was undertaken to define the molecular basis of this overlap through comparative profiling of serum proteins in RA-ILD and IPF.

METHODS

Multiplex enzyme-linked immunosorbent assays (ELISAs) were used to profile 45 protein biomarkers encompassing cytokines/chemokines, growth factors, and matrix metalloproteinases (MMPs) in sera obtained from RA patients with ILD and those without, individuals with IPF, and healthy controls. Levels of selected serum proteins were compared between patient subgroups using adjusted linear regression, principal component analysis (PCA), and least absolute shrinkage and selection operator (LASSO) modeling.

RESULTS

Multiplex ELISA-based assessment of sera from 2 independent cohorts (Veterans Affairs [VA] and Non-VA) revealed a number of non-overlapping biomarkers distinguishing RA-ILD from RA without ILD (RA-no ILD) in adjusted regression models. Parallel analysis of sera from IPF patients also yielded a discriminatory panel of protein markers in models adjusted for age/sex/smoking, which showed differential overlap with profiles linked to RA-ILD in the VA cohort versus the Non-VA cohort. PCA revealed several distinct functional groups of RA-ILD-associated markers that, in the VA cohort, encompassed proinflammatory cytokines/chemokines as well as 2 different subsets of MMPs. Finally, LASSO regression modeling in the Non-VA and VA cohorts revealed distinct biomarker combinations capable of discriminating RA-ILD from RA-no ILD.

CONCLUSION

Comparative serum protein biomarker profiling represents a viable method for distinguishing RA-ILD from RA-no ILD and identifying population-specific mediators shared with IPF.

Indications for lung transplant referral and listing

Lung transplantation is a valuable therapeutic option for many patients with severe lung disease who have exhausted other medical or surgical therapies. However, since lungs are not a manufacturable organ like artificial heart valves or left ventricular assist devices, and since they are a limited resource compared to number of patients requiring the organs, the Department of Health and Human Services set the Final Rule of organ allocation in 1998. This led to development and implementation of Lung Allocation Score (LAS) in 2005. The score broadly divides lung diseases into 4 diagnostic criteria with a coefficient factor given to each category. The score is based on the prognostic factors of each patient to determine the risk of mortality without a transplant combined with the probability of patient survival post-transplant. Most of the guidelines for "Indications for referral and listing in lung transplant" is based on consensus opinion as there is limited amount of robust data and trials about this topic. The International Society for Heart and Lung Transplant (ISHLT) has published three editions for candidate selection and listing. In this article, we have attempted to highlight the guidelines and incorporated other disease specific prognostic factors that are not captured in the LAS. Ultimately, there are other factors like geographic location, height, blood group, preformed antibodies, transplant center experience, past wait times and transplant rate, availability of organs, etc., which also play a role especially when considering listing a patient for lung transplant. We also highlighted a representative disease in each category and most criteria for that disease will apply to other diseases in that category. Finally, this article does not delve into the history and reasoning behind each guideline but is meant to provide a general overview of indications and contraindications applicable in the field of adult lung transplantation.