BACKGROUND: 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.RESEARCH QUESTION: 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)?STUDY DESIGN AND METHODS: 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 mu-tation for availability of clinical follow-up data. For comparison, 248 patients with FPF and 575 patients with sIPF were included.RESULTS: 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 6 months after diagnosis was -40 mL and median transplant-free survival was 44 months 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 1/4 7) treated for 6 months with antifibrotic drugs showed stable lung function with a median change in FVC of thorn 40 mL (interquartile range,-40 to 90 mL), whereas patients with an SRG mutation treated with immunomodulatory drugs showed a variable response dependent on the gene involved.INTERPRETATION: 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.

In sporadic idiopathic pulmonary fibrosis (sIPF) and pulmonary fibrosis caused by a mutation in telomere (TRG-PF) or surfactant related genes (SRG-PF), there are a number of aberrant cellular processes known that can lead to fibrogenesis. We investigated whether RNA expression of genes involved in these processes differed between sIPF, TRG-PF, and SRG-PF and whether expression levels were associated with survival. RNA expression of 28 genes was measured in lung biopsies of 26 sIPF, 17 TRG-PF, and 6 SRG-PF patients. Significant differences in RNA expression of TGFBR2 (p = 0.02) and SFTPA2 (p = 0.02) were found between sIPF, TRG-PF, and SRG-PF. Patients with low (<median) expression of HSPA5 (p = 0.04), COL1A1 (p = 0.03), and ATF4 (0.005) had significantly longer survival rates than patients with high (≥median) expression of these genes. In addition, we scored for low (0) or high (1) expression of six endoplasmic reticulum (ER) stress genes (HSP90B1, DDIT3, EDEM1, HSPA5, ATF4, and XBP1) and found that patients with high expression in a low number of ER stress genes (total score 0–1) had longer survival rates than patients with high expression in a high number of ER stress genes (total score 2–6) (p = 0.03). In conclusion, there are minor differences between sIPF, TRG-PF, and SRG-PF and high expression in a high number of ER stress genes significantly associated with shorter survival time, suggesting that ER stress may be a target for therapy for PF.

This study suggests that pirfenidone and nintedanib can be used safely in IPF patients with a telomerase related gene mutation and that both drugs reduce FVC decline. These results should be confirmed in a larger prospective study.https://bit.ly/3k7b4Zx

Connective tissue growth factor (CTGF) is an important mediator in fibrotic disease. Single nucleotide polymorphisms (SNPs) in CTGF have been found to be associated with different fibrotic diseases and CTGF protein was found to be upregulated in lung tissue, bronchoalveolar lavage cells, and plasma of idiopathic pulmonary fibrosis (IPF) patients. We investigated whether genetic variants predispose to sporadic IPF (spIPF), familial pulmonary fibrosis (FPF), and connective tissue disease associated ILD (CTD-ILD). In total, 294 patients with spIPF and 294 healthy individuals were genotyped for CTGF rs12526196, rs9402373, rs6918698, and rs9399005. For replication of CTGF rs6918698 findings in pulmonary fibrosis, 128 patients with FPF, 125 with CTD-ILD, and an independent control cohort of 130 individuals were included. Lung tissue of 6 IPF patients was stained for CTGF to assess pulmonary localization. Of the four SNPs, only the minor allele frequency (MAF) of CTGF rs6918698 deviated between spIPF (MAF 0.41) and controls (MAF 0.47; OR 0.774 (0.615–0.975); p = 0.030). Further comparison of CTGF rs6918698G showed a difference between FPF (MAF 0.33) and controls (MAF 0.48; OR 0.545 (0.382–0.778); p = 0.001), but not with CTD-ILD. CTGF was localized in alveolar and bronchiolar epithelium, alveolar macrophages, myofibroblasts and endothelium and highly expressed in the basal cell layer of sandwich foci. CTGF rs6918698G associates with spIPF and with FPF, but not with CTD-ILD in a Dutch cohort. CTGF is localized in lung tissue involved in IPF pathogenesis. Further research into the role of this SNP on CTGF expression and fibrogenesis is warranted.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and deadly interstitial lung disease (ILD). Over the past decade, familial occurrence of IPF led to the identification of genetic susceptibility traits [1]. Germline pathogenic variations in telomere-related genes (TRG) such as TERT, TERC TINF2, DKC1, RTEL1, PARN, NAF1, ZCCHC8, NHP2 and NOP10 have been detected in 20–30% of patients with familial pulmonary fibrosis (FPF) and in 1–5% of sporadic IPF [2–4]. In comparison with IPF patients, carriers of a TRG mutation are significantly younger and show an accelerated decline of forced vital capacity (FVC) [5–7]. Two drugs, pirfenidone and nintedanib, have been shown to reduce the decline of FVC in IPF patients [8, 9]. So far, two studies have reported on the safety and effectiveness of pirfenidone in patients with a TRG mutation [6, 7] whereas no study has investigated nintedanib in this specific population. Thus, the aim of this retrospective study was to assess safety and efficacy of nintedanib and pirfenidone in IPF patients with a TRG mutation. This study suggests that pirfenidone and nintedanib can be used safely in IPF patients with a telomerase related gene mutation and that both drugs reduce FVC decline. These results should be confirmed in a larger prospective study. https://bit.ly/3k7b4Zx

Purpose of review The current review aims to recognize the variability in clinical presentation of adult patients with bi-allelic ABCA3 mutations, create more depth in ABCA3 mutations reported and highlight the influence of environmental factors on disease course. Recent findings Mutations in ABCA3 are predominantly linked to neonatal and pediatric interstitial lung disease (ILD) with a minority surviving beyond puberty. Here, we present three patients with ABCA3 mutations who present with disease at the age of 19, 61 and 77. Moreover, we identified c.4451G>C (p.R1484P), c.1675G>A (p.G559R) and c.4745C>G (p.T1582S) as three novel ABCA3 mutations. In addition, we identified six additional patients with ABCA3 mutations in literature who reached an age above 18. Furthermore, we discuss the influence of infections, drugs and smoking on disease course. Summary Although extremely rare, patients with bi-allelic mutations in ABCA3 may present at adulthood. Late onset of disease may be influenced by type of mutation or environmental factors.

Telomere related gene (TRG) mutations are found in approximately 20% of patients with familial pulmonary fibrosis and are associated with hepatic, cutaneous and hematologic manifestations. Pirfenidone and nintedanib have been shown to slow the decline of FVC of patients with idiopathic pulmonary fibrosis (IPF). There is limited evidence of efficacy and safety of these treatments in IPF patients carrying a TRG mutation. The objective of this retrospective multicenter study was to analyze the efficacy and safety of antifibrotic drugs in IPF patients carrying a TRG mutation. We identified 103 IPF patients carrying a mutation in TERT (n=74), TERC (n=17), RTEL1 (n=10) or PARN (n=3). from 6 countries (France, Netherlands, Belgium, Spain, Greece and Switzerland) Forty-four patients received nintedanib, 59 received pirfenidone. The mean age at diagnosis was 57.9 ± 13.6 years and the median delay between diagnosis and treatment initiation was 6.0 months [3.0-15.1]. At initiation of treatment, the FVC was 80.8% ± 20.2% and the DLCO was 44.0% ± 13.7%. The median duration of treatment was 10.8 months [6.5-18.1]. Antifibrotic treatment was terminated in 18 patients because of progression of the disease and in 15 patients due to intolerable side effects, mainly digestive (nintedanib, n = 9, pirfenidone, n = 6). The median decline in FVC prior to initiation of treatment was 24.5 mL [10.5-30.1] per month. After initiation of treatment, the median decline in FVC was 18.0 mL [9.0-27.0] per month in patients treated with nintedanib and 25.4 mL per month [14.7-36.7] in patients treated with pirfenidone. This retrospective series shows that antifibrotic therapies are well tolerated in IPF patients with TRG mutations. Further analyses are needed to evaluate the efficacy.

Organoids are self-organizing 3D structures grown from stem cells that recapitulate essential aspects of organ structure and function. Here we describe a method to establish long-term-expanding human airway organoids from broncho-alveolar biopsies or lavage material. The pseudostratified airway organoid epithelium consists of basal cells, functional multi-ciliated cells, mucus-producing goblet cells, and CC10-secreting club cells. Airway organoids derived from cystic fibrosis (CF) patients allow assessment of CFTR function in an organoid swelling assay. Organoid culture conditions also allow gene editing as well as the derivation of various types of lung cancer organoids. Respiratory syncytial virus (RSV) infection recapitulated central disease features and dramatically increases organoid cell motility, found to be driven by the non-structural viral NS2 protein. We conclude that human airway organoids represent versatile models for the in vitro study of hereditary, malignant, and infectious pulmonary disease.

Fibrotic interstitial pneumonias are a group of rare diseases characterised by distortion of lung interstitium. Patients with mutations in surfactant-processing genes, such as surfactant protein C (SFTPC), surfactant protein A1 and A2 (SFTPA1 and A2), ATP binding cassette A3 (ABCA3) and Hermansky-Pudlak syndrome (HPS1, 2 and 4), develop progressive pulmonary fibrosis, often culminating in fatal respiratory insufficiency. Although many mutations have been described, little is known about the optimal treatment strategy for fibrotic interstitial pneumonia patients with surfactant-processing mutations. We performed a systematic literature review of studies that described a drug effect in patients, cell or mouse models with a surfactant-processing mutation. In total, 73 articles were selected, consisting of 55 interstitial lung disease case reports/series, two clinical trials and 16 cell or mouse studies. Clinical effect parameters included lung function, radiological characteristics and clinical symptoms, while experimental outcome parameters included chemokine/cytokine expression, surfactant trafficking, necrosis and apoptosis. SP600125, a c-jun N-terminal kinase (JNK) inhibitor, hydroxychloroquine and 4-phenylbutyric acid were most frequently studied in disease models and lead to variable outcomes, suggesting that outcome is mutation dependent. This systematic review summarises effect parameters for future studies on surfactant-processing disorders in disease models and provides directions for future trials in affected patients.

Fibrotic interstitial pneumonias are a group of rare diseases characterised by distortion of lung interstitium. Patients with mutations in surfactant-processing genes, such as surfactant protein C (SFTPC), surfactant protein A1 and A2 (SFTPA1 and A2), ATP binding cassette A3 (ABCA3) and Hermansky–Pudlak syndrome (HPS1, 2 and 4), develop progressive pulmonary fibrosis, often culminating in fatal respiratory insufficiency. Although many mutations have been described, little is known about the optimal treatment strategy for fibrotic interstitial pneumonia patients with surfactant-processing mutations. We performed a systematic literature review of studies that described a drug effect in patients, cell or mouse models with a surfactant-processing mutation. In total, 73 articles were selected, consisting of 55 interstitial lung disease case reports/series, two clinical trials and 16 cell or mouse studies. Clinical effect parameters included lung function, radiological characteristics and clinical symptoms, while experimental outcome parameters included chemokine/cytokine expression, surfactant trafficking, necrosis and apoptosis. SP600125, a c-jun N-terminal kinase (JNK) inhibitor, hydroxychloroquine and 4-phenylbutyric acid were most frequently studied in disease models and lead to variable outcomes, suggesting that outcome is mutation dependent. This systematic review summarises effect parameters for future studies on surfactant-processing disorders in disease models and provides directions for future trials in affected patients. Drug effects in disease models of surfactant-processing disease are highly dependent on mutation http://ow.ly/ZYZH30k3RkK

Pulmonary fibrosis is the main cause of severe morbidity and mortality in idiopathic interstitial pneumonias (IIP). In the past years, there has been major progress in the discovery of genetic factors that contribute to disease. Genes with highly penetrant mutations or strongly predisposing common risk alleles have been identified in familial and sporadic IIP. This review summarizes genes harbouring causative rare mutations and replicated common predisposing alleles. To date, rare mutations in nine different genes and five risk alleles fulfil this criterion. Mutated genes represent three genes involved in surfactant homeostasis and six genes involved in telomere maintenance. We summarize gene function, gene expressing cells, and pathological consequences of genetic alterations associated with disease. Consequences of the genetic alteration include dysfunctional surfactant processing, ER stress, immune dysregulation, and maintenance of telomere length. Biological evidence shows that these processes point towards a central role for alveolar epithelial type II cell dysfunction. However, tabulation also shows that function and consequence of most common risk alleles are not known. Most importantly, the predisposition of the MUC5B risk allele to disease is not understood. We propose a mechanism whereby MUC5B decreases surface tension lowering capacity of alveolar surfactant at areas with maximal mechanical stress.