Familial Pulmonary Fibrosis Research Articles

The management of Familial Pulmonary Fibrosis in different medical settings: Where does that leave us? An Italian nationwide survey.

Familial Pulmonary Fibrosis (FPF) is an emerging group of interstitial lung diseases (ILDs) caused by mutations mainly involving "telomere-related genes" and "surfactant-related genes". Although, in 2023, European Respiratory Society proposed a statement for FPFs management, these still remain a burden. Our work aimed to evaluate the management and impact of FPF in three Italian different medical settings: University Hospitals (UHs), non-University Hospitals (N-UHs) and outpatient clinics. This survey was created by ILDs Study Group Società Italiana di Pneumologia/ Italian Respiratory Society (SIP-IRS) and diffused via email to all SIP-IRS members. The descriptive statistical analysis was conducted through GraphPad Prism software (version 8.0). Results: Twenty participants replied to the survey, of which 65% (13/20) worked at UH while the remaining 25% (6/20) and 5% (1/20) worked at N-UH and outpatient clinics, respectively. Centers with, at least, 150 ILD patients visits/year followed a higher number of FPF patients, regardless of University affiliation (p=0.0046). Despite significant discrepancies in genetic testing and availability of counselling were registered, no statistically significant differences in patients' anamnesis assessment were observed between UHs and N-UHs (p=0.4192 and p=0.6525). However, there were relevant differences in the number of FPF patients undergoing genetic assessment in the Centers with Genetics Lab or Unit inside the Hospital (p=0.0253). There was no consensus regarding the impact of FPF diagnosis on lung transplantation and screening of asymptomatic relatives. Similarly, no differences were reported in antifibrotic prescriptions between UHs and N-UHs. Although the typical UIP pattern was the most common radiological pattern observed in FPF patients, there were no differences in the prevalence of histopathological patterns between UH and N-UH. Improving pulmonologists' knowledge of the approach, diagnosis and management of FPF is a global medical topic. Scientific societies can provide significant support in raising physicians' awareness of this issue.

Genetic background of pulmonary (vascular) diseases - how much is written in the codes?

To provide a comprehensive overview of the underlying genetic defects of pulmonary (vascular) diseases and novel treatment avenues. Pulmonary arterial hypertension (PAH) is the prime example of a pulmonary vascular disease, which can be caused by genetic mutations in some patients. Germline mutations in the BMPR2 gene and further genes lead to vessel remodelling, increase of pulmonary vascular resistance and onset of heritable PAH. The PAH genes with the highest evidence and strategies for genetic testing and counselling have been assessed and evaluated in 2023 by international expert consortia. Moreover, first treatment options have just arisen targeting the molecular basis of PAH. Apart from PAH, this review touches on the underlying genetic causes of further lung diseases including alpha 1 antitrypsin deficiency, cystic fibrosis, familial pulmonary fibrosis and lymphangioleiomyomatosis. We point out the main disease genes, the underlying pathomechanisms and novel therapies trying not only to relieve symptoms but to treat the molecular causes of the diseases.

Syndromic genetic causes of pulmonary fibrosis.

The identification of extra-pulmonary symptoms plays a crucial role in diagnosing interstitial lung disease (ILD). These symptoms not only indicate autoimmune diseases but also hint at potential genetic disorders, suggesting a potential overlap between genetic and autoimmune origins. Genetic factors contributing to ILD are predominantly associated with telomere (TRG) and surfactant-related genes. While surfactant-related gene mutations typically manifest with pulmonary involvement alone, TRG mutations were initially linked to syndromic forms of pulmonary fibrosis, known as telomeropathies, which may involve hematological and hepatic manifestations with variable penetrance. Recognizing extra-pulmonary signs indicative of telomeropathy should prompt the analysis of TRG mutations, the most common genetic cause of familial pulmonary fibrosis. Additionally, various genetic diseases causing ILD, such as alveolar proteinosis, alveolar hemorrhage, or unclassifiable pulmonary fibrosis, often present as part of syndromes that include hepatic, hematological, or skin disorders. This review explores the main genetic conditions identified over the past two decades.

Clinical, radiological and histopathological features of patients with familial pulmonary fibrosis

BackgroundIn familial pulmonary fibrosis (FPF) at least two biological relatives are affected. Patients with FPF have diverse clinical features.Research questionWe aimed to characterize demographic and clinical features, re-evaluate high-resolution computed tomography (HRCT) scans and histopathology of surgical lung biopsies, assess survival and investigate the suitability of risk prediction models for FPF patients.Study designA retrospective cohort study.MethodsFPF data (n = 68) were collected from the medical records of Oulu University Hospital (OUH) and Oulaskangas District Hospital between 1 Jan 2000 and 11 Jan 2023. The inclusion criterion was pulmonary fibrosis (PF) (ICD 10-code J84.X) and at least one self-reported relative with PF. Clinical information was gathered from hospital medical records. HRCT scans and histology were re-evaluated.ResultsThirty-seven (54.4%) of the patients were men, and 31 (45.6%) were women. The mean ages of the women and men were 68.6 and 61.7 years, respectively (p = 0.003). Thirty-seven (54.4%) patients were nonsmokers. The most common radiological patterns were usual interstitial pneumonia (UIP) (51/75.0%), unclassifiable (8/11.8%) and nonspecific interstitial pneumonia (NSIP) (3/4.4%). Pleuroparenchymal fibroelastosis (PPFE) was observed as a single or combined pattern in 13.2% of the patients. According to the 2022 guidelines for idiopathic pulmonary fibrosis (IPF), the patients were categorized as UIP (31/45.6%), probable UIP (20/29.4%), indeterminate for UIP (7/10.3%) or alternative diagnosis (10/14.7%). The histopathological patterns were UIP (7/41.2%), probable UIP (1/5.9%), indeterminate for UIP (8/47.2%) and alternative diagnosis (1/5.9%). Rare genetic variants were found in 9 patients; these included telomerase reverse transcriptase (TERT, n = 6), telomerase RNA component (TERC, n = 2) and regulator of telomere elongation helicase 1 (RTEL1, n = 1). Half of the patients died (n = 29) or underwent lung transplantation (n = 5), with a median survival of 39.9 months. The risk prediction models composite physiology index (CPI), hazard ratio (HR) 1.07 (95.0% CI 1.04–1.10), and gender-age-physiology index (GAP) stage I predicted survival statistically significantly (p<0.001) compared to combined stages II and III.ConclusionsThis study confirmed the results of earlier studies showing that FPF patients’ radiological and histopathological patterns are diverse. Moreover, radiological and histological features revealed unusual patterns and their combinations.

Clinical Impact of Telomere Length Testing for Interstitial Lung Disease

BackgroundShortened telomere length (TL) is a genomic risk factor for fibrotic interstitial lung disease (ILD), but its role in clinical management is unknown. Research QuestionWhat is the clinical impact of TL testing on the management of ILD? Study Design and MethodsPatients were evaluated in the Columbia University ILD clinic and underwent CLIA-certified TL testing by flow cytometry and fluorescence in-situ hybridization (FlowFISH) as part of clinical management. Short TL was defined as below the 10th age-adjusted percentile for either granulocytes or lymphocytes by FlowFISH. Patients were offered genetic counseling and testing if they had short TL or a family history of ILD. FlowFISH TL was compared against research qPCR TL measurement. ResultsA total of 108 patients underwent TL testing, including those with clinical features of short telomere syndrome such as familial pulmonary fibrosis (50%) or extrapulmonary manifestations in the patient (25%) or a relative (41%). The overall prevalence of short TL was 46% and was similar across clinical ILD diagnoses. The number of short telomere clinical features was independently associated with detecting short TL (OR 2.00, 95% CI [1.27, 3.32]). TL testing led to clinical management changes for 35 (32%) patients, most commonly resulting in reduction or avoidance of immunosuppression. Of the patients who underwent genetic testing (n=34), a positive or candidate diagnostic finding in telomere-related genes was identified in 10 (29%) patients. Inclusion of TL testing below the 1st percentile helped reclassify 8 of 9 variants of uncertain significance (VUS) into actionable findings. The qPCR test correlated with FlowFISH, but age-adjusted percentile cutoffs may not be equivalent between the two assays. InterpretationIncorporating TL testing in ILD impacted clinical management and led to the discovery of new actionable genetic variants.

GC–MS analysis of Lactobacillus plantarum YW11 metabolites and its computational analysis on familial pulmonary fibrosis hub genes

Abstract The purpose of this research was to examine the interaction between metabolites of Lactobacillus plantarum YW11, characterized through GC–mass spectra (MS) analysis, and the FN1 protein in cases of familial pulmonary fibrosis, found from hub genes analysis. GC–MS analysis was performed to identify metabolites in L. plantarum. Then, gene expression analysis and functional annotations were conducted to investigate the hub genes. A network of hub genes and transcription factors (TFs) was constructed, highlighting the significance of FN1 in the disease’s etiology. Molecular docking was employed to explore the interaction between the characterized metabolites and the FN1 protein. Toxicity analysis was also carried out. Thirty-two active compounds of L. plantarum YW11 were characterized by GC–MS. The gene expression analysis identified 295 differentially expressed genes, including 10 hub genes and 6 TFs, providing further support for the involvement of FN1 protein in the disease. The results of the molecular docking studies suggest the therapeutic potential of targeting FN1, with the best docking result observed for the interaction between FN1 and the 2,4-di-tert-butylphenol metabolite (energy of −6.9 kcal/mol). The toxicity analysis and molecular dynamic simulations support the suitability of 2,4-di-tert-butylphenol as a candidate for targeting FN1.

Genetic Testing Goes Beyond Imaging and Histological Evaluation in Pleuroparenchymal Fibroelastosis

BackgroundLung biopsy remains the gold standard in the diagnosis of fibrotic interstitial lung disease (F-ILD), but there is a growing appreciation of the role of pathogenic gene variants in telomere and surfactant protein genes, especially in familial pulmonary fibrosis (FPF). Pleuroparenchymal fibroelastosis (PPFE) is a rare disease that can coexist with different patterns of F-ILD, including FPF. It can be progressive and often leads to respiratory failure and death. This study tested the hypothesis that genetic testing goes beyond radiological and histological findings in PPFE and other F-ILD further informing clinical decision-making for patients and affected family members by identifying pathological gene variants in telomere and surfactant protein genes.MethodsThis is a retrospective review of 70 patients with F-ILD in the setting of FPF or premature lung fibrosis. Six out of 70 patients were diagnosed with PPFE based on radiological or histological characteristics. All patients underwent telomere length evaluation in peripheral blood by Flow-FISH or genetic testing using a customized exome-based panel that included telomere and surfactant protein genes associated with lung fibrosis.ResultsHerein, we identified six individuals where radiographic or histopathological analyses of PPFE were linked with telomere biology disorders (TBD) or variants in surfactant protein genes. Each case involved individuals with either personal early-onset lung fibrosis or a family history of the disease. Assessments of telomere length and genetic testing offered insights beyond traditional radiological and histopathological evaluations.ConclusionDetecting anomalies in TBD-related or surfactant protein genes can significantly refine the diagnosis and treatment strategies for individuals with PPFE and other F-ILD.

A Test to Comprehensively Capture the Known Genetic Component of Familial Pulmonary Fibrosis.

The recent European Respiratory Society statement on familial pulmonary fibrosis supports the need for genetic testing in the care of patients and their relatives. However, no solution (i.e., a concrete test) was provided to implement genetic testing in daily practice. Herein, we tabulated and standardized the nomenclature of 128 genetic variants in 20 genes implicated in adult-onset pulmonary fibrosis. The objective was to develop a laboratory-developed test (LDT) on the basis of standard Sanger sequencing to capture all known familial pulmonary fibrosis-associated variants. Targeted DNA fragments were amplified using harmonized PCR conditions to perform the LDT in a single 96-well plate. The new genetic test was evaluated in 62 sporadic cases of idiopathic pulmonary fibrosis. As expected in this population, we observed a low yield of disease-causing mutations. More important, 100% of targeted variants by the LDT were successfully evaluated. Furthermore, four variants of uncertain significance with in silico-predicted deleterious scores were identified in three patients, suggesting novel pathogenic variants in genes known to cause idiopathic pulmonary fibrosis. Finally, the MUC5B promoter variant rs35705950 was strongly enriched in these patients with a minor allele frequency of 41.1% compared with 10.6% in a matched population-based cohort (n = 29,060), leading to an estimation that this variant may explain up to 35% of the population-attributable risk. This LDT provides a solution for rapid clinical translation. Technical laboratory details are provided so that specialized pulmonary centers can implement the LDT in house to expedite the clinical recommendations of expert panels.

Familial Pulmonary Fibrosis: A Case Report

This report describes a unique case of familial pulmonary fibrosis, with similar clinical findings to idiopathic pulmonary fibrosis, but seen in several cousins of the same family. The prevalence of familial pulmonary fibrosis is likely underestimated, primarily due to a lack of surveillance, as pulmonary fibrosis is frequently perceived as acquired or idiopathic condition. Recent advancements have led to the identification of several genes linked to familial pulmonary fibrosis, highlighting the potential for targeted therapies as promising future treatment methods.

Genetic and environmental factors in interstitial lung diseases: current and future perspectives on early diagnosis of high-risk cohorts.

Within the wide scope of interstitial lung diseases (ILDs), familial pulmonary fibrosis (FPF) is being increasingly recognized as a specific entity, with earlier onset, faster progression, and suboptimal responses to immunosuppression. FPF is linked to heritable pathogenic variants in telomere-related genes (TRGs), surfactant-related genes (SRGs), telomere shortening (TS), and early cellular senescence. Telomere abnormalities have also been identified in some sporadic cases of fibrotic ILD. Air pollution and other environmental exposures carry additive risk to genetic predisposition in pulmonary fibrosis. We provide a perspective on how these features impact on screening strategies for relatives of FPF patients, interstitial lung abnormalities, ILD multi-disciplinary team (MDT) discussion, and disparities and barriers to genomic testing. We also describe our experience with establishing a familial interstitial pneumonia (FIP) clinic and provide guidance on how to identify patients with telomere dysfunction who would benefit most from genomic testing.

NKX2.1 mutation revealed by a lymphoid interstitial pneumonia in an adult with rheumatoid arthritis.

This is the first case of a 37-year-old female patient carrier of a heterozygous NKX2.1 mutation associated with RA-ILD with a histological pattern of LIP. This case illustrates the wide panel of ILD subtypes associated with NKX2.1 mutations. https://bit.ly/3F49OTS.

Histopathological evaluation of induced pulmonary fibrosis under the effect of montelukast

Pulmonary fibrosis (PF) is an interstitial lung disease leading to scarring of the lung. There are several types of lung fibrosis as familial pulmonary fibrosis, idiopathic pulmonary fibrosis, and others associated with non-specific&#x0D; &#x0D; interstitial pneumonia. The most common type is idiopathic pulmonary fibrosis which is an unknown cause. Lung fibrosis causes changes in the histology of the lung by the disappearance of the lung parenchyma, replaced by an inflammatory infiltrate, and mild thickening of the pulmonary artery. The management of pulmonary fibrosis included Azathioprine, corticosteroid, and N-acetyl cysteinyl in 2011 but in 2014 this guideline was removed and replaced by nintedanib and pirfenidone. This study used Pirfenidone, as standard therapy for the treatment of pulmonary fibrosis, and montelukast is Cysteinyl leukotrienes (CysLT) antagonist which binds to its receptor (CysLTE4) located on smooth muscle cells of the respiratory airway causing anti-inflammatory effect by inhibition of inflammatory markers as TGFβ1. Sixty male rats were divided into five groups,12 rats for each group where the control group received distilled water by gastric gavage, the induction group received bleomycin intratracheally as a single dose, the pirfenidone group received pirfenidone 50mg/kg, montelukast group received montelukast 20mg/kg and the combination group received a half dose of pirfenidone and montelukast. After twenty-eight days after the treatment with montelukast or pirfenidone sacrifice rats and collect the organ (lungs) from each group were then placed in buffer formalin 10% for histopathological study. After 14 days from bleomycin dose, results show that bleomycin cause massive disappearance of pulmonary parenchyma that was replaced by an inflammatory infiltrate and medial thickening of the pulmonary artery in all groups, but montelukast and pirfenidone show normal lung paranchyma and pulmonary artery after 28 days of treatment in pirfenidone, montelukast, and combination groups.&#x0D; In conclusion, that bleomycin changes the histology of the lung causing induction of lung fibrosis in all groups after 14 days except control group but pirfenidone, montelukast, and combination of half dose of pirfenidone with a half dose of montelukast return the lung to normal architecture after 28 days of treatment.

Optimizing Screening for Early Disease Detection in Familial Pulmonary Fibrosis (FLORIS): A Prospective Cohort Study Design.

Background: Familial pulmonary fibrosis (FPF) can be defined as pulmonary fibrosis in two or more first-degree family members. The first-degree family members of FPF patients are at high risk of developing FPF and are eligible for screening. Reproducible studies investigating risk factors for disease are much needed. Methods: Description of the screening study protocol for a single-center, prospective cohort study; the study will include 200 asymptomatic, first-degree family members of patients with FPF who will undergo three study visits in two years. The primary objective is determining the diagnostic value of parameters for detection of early FPF; the secondary objectives are determining the optimal timing of the screening interval and gaining insight into the natural history of early FPF. The presence of interstitial lung disease (ILD) changes on high-resolution computed tomography of the chest is indicative of preclinical ILD; the changes are determined at baseline. The comparison between the group with and without ILD changes is made for clinical parameters (pulmonary function, presence of digital clubbing, presence of Velcro-like crackles, blood count, liver- and kidney-function testing, patient-reported cough and dyspnea score) and exploratory parameters. Discussion: This study will be the first large-size, prospective, longitudinal cohort study for yearly screening of asymptomatic family members of FPF patients investigating the diagnostic value of parameters, including lung function, to detect early FPF. More effective screening strategies could advance early disease detection.

Radiographic Lung Abnormalities in First-Degree Relatives of Patients With Different Subtypes of Pulmonary Fibrosis

Early interstitial lung disease (ILD) has been detected in 14% to 22% of screened relatives of patients with familial pulmonary fibrosis.1,2 Relatives of patients with sporadic IPF have been found with a higher prevalence of interstitial lung abnormalities (ILA) and preclinical ILD than the general population.3 Despite advances made in screening, many previous cohorts have excluded individuals with nonidiopathic pulmonary fibrosis (IPF) ILD. Therefore, we sought to determine the prevalence of subclinical ILD in family members of patients with fibrotic ILD, regardless of subtype.

The Genetic Landscape of Familial Pulmonary Fibrosis.

Rationale and Objectives: Up to 20% of idiopathic interstitial lung disease is familial, referred to as familial pulmonary fibrosis (FPF). An integrated analysis of FPF genetic risk was performed by comprehensively evaluating for genetic rare variants (RVs) in a large cohort of FPF kindreds. Methods: Whole-exome sequencing and/or candidate gene sequencing from affected individuals in 569 FPF kindreds was performed, followed by cosegregation analysis in large kindreds, gene burden analysis, gene-based risk scoring, cell-type enrichment analysis, and coexpression network construction. Measurements and Main Results: It was found that 14.9-23.4% of genetic risk in kindreds could be explained by RVs in genes previously linked to FPF, predominantly telomere-related genes. New candidate genes were identified in a small number of families-including SYDE1, SERPINB8, GPR87, and NETO1-and tools were developed for evaluation and prioritization of RV-containing genes across kindreds. Several pathways were enriched for RV-containing genes in FPF, including focal adhesion and mitochondrial complex I assembly. By combining single-cell transcriptomics with prioritized candidate genes, expression of RV-containing genes was discovered to be enriched in smooth muscle cells, type II alveolar epithelial cells, and endothelial cells. Conclusions: In the most comprehensive FPF genetic study to date, the prevalence of RVs in known FPF-related genes was defined, and new candidate genes and pathways relevant to FPF were identified. However, new RV-containing genes shared across multiple kindreds were not identified, thereby suggesting that heterogeneous genetic variants involving a variety of genes and pathways mediate genetic risk in most FPF kindreds.

Genomic Fingerprint Associated with Familial Idiopathic Pulmonary Fibrosis: A Review.

Idiopathic pulmonary fibrosis (IPF) is a severe interstitial lung disease; although the recent introduction of two anti-fibrosis drugs, pirfenidone and Nidanib, have resulted in a significant reduction in lung function decline, IPF is still not curable. Approximately 2-20% of patients with IPF have a family history of the disease, which is considered the strongest risk factor for idiopathic interstitial pneumonia. However, the genetic predispositions of familial IPF (f-IPF), a particular type of IPF, remain largely unknown. Genetics affect the susceptibility and progression of f-IPF. Genomic markers are increasingly being recognized for their contribution to disease prognosis and drug therapy outcomes. Existing data suggest that genomics may help identify individuals at risk for f-IPF, accurately classify patients, elucidate key pathways involved in disease pathogenesis, and ultimately develop more effective targeted therapies. Since several genetic variants associated with the disease have been found in f-IPF, this review systematically summarizes the latest progress in the gene spectrum of the f-IPF population and the underlying mechanisms of f-IPF. The genetic susceptibility variation related to the disease phenotype is also illustrated. This review aims to improve the understanding of the IPF pathogenesis and facilitate his early detection.

Evolving Concepts and Controversies in Interstitial Lung diseases: Update in 2023

Recent studies elicited evolving concepts and controversies in interstitial lung diseases and proposed substantial changes in diagnostic and therapeutic approaches to interstitial lung diseases. Dr. Averill A. Liebow first coined the term usual interstitial pneumonia (UIP) in 1960’s as distinct pathologic pattern of fibrosis in idiopathic pulmonary fibrosis (IPF), the prototype of progressive fibrosing interstitial lung disease with poor prognosis. Advances in omics led to a better understanding of molecular pathogenesis of UIP and shed light on various types of familial pulmonary fibrosis as well as familial IPF. The concept of progressive pulmonary fibrosis was introduced to acknowledge additional types of progressive fibrosing interstitial lung diseases with the clinical and pathologic phenotypes very similar to those of UIP/IPF. As such, some authors have proposed a paradigm shift by considering UIP as a stand-alone diagnostic entity to encompass other fibrosing interstitial lung diseases that undergo the same relentless progression as IPF. Cicatricial organizing pneumonia is a variant of organizing pneumonia that can be reminiscent of UIP on histopathology but usually follows a stable clinical course unlike UIP. There has been significant disconnection in fundamental understanding as well as diagnostic criteria of lymphocytic interstitial pneumonia among pathologists, pulmonologists and radiologists, which needs to be resolved. The concept and histopathologic criteria of granulomatous and lymphocytic interstitial lung disease are also elusive and require clarification as well. In this review, these topics will be covered based on current literature.

1271: MUCINOUS ADENOCARCINOMA MIMICKING INTERSTITIAL LUNG DISEASE DISCOVERED POST-TRANSPLANT

Introduction: Mucinous adenocarcinomas typically present with cough, dyspnea and pleuritic chest pain. They have a wide range of radiographic appearances including a single nodule, lobar consolidation, or diffuse nodules. These tumors can mimic infectious and non-infectious pulmonary pathologies both clinically and radiographically. We report a rare case of invasive mucinous adenocarcinoma, mimicking interstitial lung disease discovered post bilateral lung transplant. Unfortunately, the diagnosis was made after lung transplantation posing a challenge in the management of immunosuppression in the setting of malignancy. Description: A 47-year old male with no prior medical history initially presented with progressive dyspnea on exertion for several months. Family history was significant for pulmonary fibrosis in his mother. High resolution CT chest showed extensive ground-glass opacification, upper lobe honeycombing, and consolidative changes with air bronchograms in bilateral lower lobes. Autoimmune workup and hypersensitivity pneumonitis panel were negative. Bronchoscopy and multiple sputum cultures were unrevealing. Genetic testing identified a mutation in the SFTPA2 gene, associated with familial pulmonary fibrosis. Patient’s respiratory status improved with intravenous steroids and he was discharged with oxygen supplementation, prednisone and nintedanib. However, patient was admitted two months later with clinical deterioration and acute hypoxemic respiratory failure requiring venovenous extracorporeal membrane oxygenation as a bridge to successful bilateral lung transplantation. A lung biopsy prior to transplant could not be obtained given the rapid progression of patient’s respiratory failure. Subsequently, pathology of the explanted lungs showed invasive mucinous adenocarcinoma with metastatic disease to a perihilar lymph node. PET CT scan was negative for extra thoracic metastasis. Discussion: After a multidisciplinary discussion, it was decided to continue immunosuppression with tacrolimus and a decreased dose of mycophenolate. Additionally, active surveillance with PET CT scans every three months was recommended. This case highlights the difficulties faced in the diagnosis of pulmonary adenocarcinoma due to its clinical and radiographic overlap with interstitial lung disease.

The Genetic and Epigenetic Footprint in Idiopathic Pulmonary Fibrosis and Familial Pulmonary Fibrosis: A State-of-the-Art Review.

Idiopathic pulmonary fibrosis (IPF) is a rare disease of the lung with a largely unknown etiology and a poor prognosis. Intriguingly, forms of familial pulmonary fibrosis (FPF) have long been known and linked to specific genetic mutations. There is little evidence of the possible role of genetics in the etiology of sporadic IPF. We carried out a non-systematic, narrative literature review aimed at describing the main known genetic and epigenetic mechanisms that are involved in the pathogenesis and prognosis of IPF and FPF. In this review, we highlighted the mutations in classical genes associated with FPF, including those encoding for telomerases (TERT, TERC, PARN, RTEL1), which are also found in about 10-20% of cases of sporadic IPF. In addition to the Mendelian forms, mutations in the genes encoding for the surfactant proteins (SFTPC, SFTPA1, SFTPA2, ABCA3) and polymorphisms of genes for the mucin MUC5B and the Toll-interacting protein TOLLIP are other pathways favoring the fibrogenesis that have been thoroughly explored. Moreover, great attention has been paid to the main epigenetic alterations (DNA methylation, histone modification and non-coding RNA gene silencing) that are emerging to play a role in fibrogenesis. Finally, a gaze on the shared mechanisms between cancer and fibrogenesis, and future perspectives on the genetics of pulmonary fibrosis have been analyzed.

Progressive Disease With Low Survival in Adult Patients With Pulmonary Fibrosis Carrying Surfactant-Related Gene Mutations: An Observational Study

In some patients with progressive fibrosing interstitial lung disease (ILD), disease is caused by carriage of a mutation in a surfactant-related gene (SRG) such as SFTPC, SFTPA2, or ABCA3. However, no aggregated data on disease evolution and treatment outcome have been presented for these patients. In adult patients with ILD with an SRG mutation, what is the course of lung function after diagnosis and during treatment and the survival in comparison with patients with sporadic idiopathic pulmonary fibrosis (sIPF) and familial pulmonary fibrosis (FPF)? We retrospectively examined the clinical course of a cohort of adults with an SRG mutation by screening 48 patients from 20 families with an SRG mutation for availability of clinical follow-up data. For comparison, 248 patients with FPF and 575 patients with sIPF were included. Twenty-three patients with ILD (median age: 45 years; 11 men) with an SRG mutation fulfilled criteria. At diagnosis, patients with an SRG mutation were younger and less often male, but had lower FVC (72%predicted) and diffusing capacity of the lungs for carbon monoxide (46%predicted) compared with patients with FPF or sIPF. In the SRG mutation group, median FVC decline 6months after diagnosis was -40mL and median transplant-free survival was 44months and not different from patients with FPF or sIPF. FVC course was not different among the three cohorts; however, a significantly larger decrease in FVC was found while patients received immunomodulatory or antifibrotic treatment compared with those receiving no treatment. Subsequent analysis in the SRG group showed that patients with a surfactant mutation (n= 7) treated for 6months with antifibrotic drugs showed stable lung function with a median change in FVC of+40mL (interquartile range, -40 to 90mL), whereas patients with an SRG mutation treated with immunomodulatory drugs showed a variable response dependent on the gene involved. This study showed that patients with ILD carrying an SRG mutation experience progressive loss of lung function with severely reduced survival despite possible beneficial effects of treatment.