Patients with interstitial lung disease (ILD) may have features of connective tissue disease (CTD), but lack findings diagnostic of a specific CTD. A recent European Respiratory Society/American Thoracic Society research statement proposed criteria for patients with interstitial pneumonia with autoimmune features (IPAF). We applied IPAF criteria to patients with idiopathic interstitial pneumonia and undifferentiated CTD-ILD (UCTD). We then characterised the clinical, serological and morphological features of the IPAF cohort, compared outcomes to other ILD cohorts and validated individual IPAF domains using survival as an endpoint. Of 422 patients, 144 met IPAF criteria. Mean age was 63.2 years with a slight female predominance. IPAF cohort survival was marginally better than patients with idiopathic pulmonary fibrosis, but worse than CTD-ILD. A non-usual interstitial pneumonia pattern was associated with improved survival, as was presence of the clinical domain. A modified IPAF cohort of those meeting the clinical domain and a radiographic or histological feature within the morphological domain displayed survival similar to those with CTD-ILD. IPAF is common among patients with idiopathic interstitial pneumonia and UCTD. Specific IPAF features can identify subgroups with differential survival. Further research is needed to replicate these findings and determine whether patients meeting IPAF criteria benefit from immunosuppressive therapy.

Background The INBUILD trial investigated the efficacy and safety of nintedanib versus placebo in patients with progressive fibrosing interstitial lung diseases (ILDs) other than idiopathic pulmonary fibrosis (IPF). We aimed to establish the effects of nintedanib in subgroups based on ILD diagnosis. Methods The INBUILD trial was a randomised, double-blind, placebo-controlled, parallel group trial done at 153 sites in 15 countries. Participants had an investigator-diagnosed fibrosing ILD other than IPF, with chest imaging features of fibrosis of more than 10% extent on high resolution CT (HRCT), forced vital capacity (FVC) of 45% or more predicted, and diffusing capacity of the lung for carbon monoxide (DLco) of at least 30% and less than 80% predicted. Participants fulfilled protocol-defined criteria for ILD progression in the 24 months before screening, despite management considered appropriate in clinical practice for the individual ILD. Participants were randomly assigned 1:1 by means of a pseudorandom number generator to receive nintedanib 150 mg twice daily or placebo for at least 52 weeks. Participants, investigators, and other personnel involved in the trial and analysis were masked to treatment assignment until after database lock. In this subgroup analysis, we assessed the rate of decline in FVC (mL/year) over 52 weeks in patients who received at least one dose of nintedanib or placebo in five prespecified subgroups based on the ILD diagnoses documented by the investigators: hypersensitivity pneumonitis, autoimmune ILDs, idiopathic non-specific interstitial pneumonia, unclassifiable idiopathic interstitial pneumonia, and other ILDs. The trial has been completed and is registered with ClinicalTrials.gov, number NCT02999178.

Rationale: Idiopathic pulmonary fibrosis (IPF) is a devastating lung disease of unknown etiology. The genes TOLLIP and MUC5B play important roles in lung host defense, which is an immune process influenced by oxidative signaling. Whether polymorphisms in TOLLIP and MUC5B modify the effect of immunosuppressive and antioxidant therapy in individuals with IPF is unknown.Objectives: To determine whether single-nucleotide polymorphisms (SNPs) within TOLLIP and MUC5B modify the effect of interventions in subjects participating in the Evaluating the Effectiveness of Prednisone, Azathioprine, and N-Acetylcysteine in Patients with Idiopathic Pulmonary Fibrosis (PANTHER-IPF) clinical trial.Methods: SNPs within TOLLIP (rs5743890/rs5743894/rs5743854/ rs3750920) and MUC5B (rs35705950) were genotyped. Interaction modeling was conducted with multivariable Cox regression followed by genotype-stratified survival analysis using a composite endpoint of death, transplantation, hospitalization, or a decline of >10% in FVC.Measurements and Main Results: Significant interaction was observed between N-acetylcysteine (NAC) therapy and rs3750920 within TOLLIP (P interaction = 0.001). After stratifying by rs3750920 genotype, NAC therapy was associated with a significant reduction in composite endpoint risk (hazard ratio, 0.14; 95% confidence interval, 0.02-0.83; P = 0.03) in those with a TT genotype, but a nonsignificant increase in composite endpoint risk (hazard ratio, 3.23; 95% confidence interval, 0.79-13.16; P = 0.10) was seen in those with a CC genotype. These findings were then replicated in an independent IPF cohort.Conclusions: NAC may be an efficacious therapy for individuals with IPF with an rs3750920 (TOLLIP) TT genotype, but it was associated with a trend toward harm in those with a CC genotype. A genotype-stratified prospective clinical trial should be conducted before any recommendation regarding the use of off-label NAC to treat IPF.

SummaryBackgroundIdiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease with high mortality, uncertain cause, and few treatment options. Studies have identified a significant genetic risk associated with the development of IPF; however, mechanisms by which genetic risk factors promote IPF remain unclear. We aimed to identify genetic variants associated with IPF susceptibility and provide mechanistic insight using gene and protein expression analyses.MethodsWe used a two-stage approach: a genome-wide association study in patients with IPF of European ancestry recruited from nine different centres in the UK and controls selected from UK Biobank (stage 1) matched for age, sex, and smoking status; and a follow-up of associated genetic variants in independent datasets of patients with IPF and controls from two independent US samples from the Chicago consortium and the Colorado consortium (stage 2). We investigated the effect of novel signals on gene expression in large transcriptomic and genomic data resources, and examined expression using lung tissue samples from patients with IPF and controls.Findings602 patients with IPF and 3366 controls were selected for stage 1. For stage 2, 2158 patients with IPF and 5195 controls were selected. We identified a novel genome-wide significant signal of association with IPF susceptibility near A-kinase anchoring protein 13 (AKAP13; rs62025270, odds ratio [OR] 1·27 [95% CI 1·18–1·37], p=1·32 × 10−9) and confirmed previously reported signals, including in mucin 5B (MUC5B; rs35705950, OR 2·89 [2·56–3·26], p=1·12 × 10−66) and desmoplakin (DSP; rs2076295, OR 1·44 [1·35–1·54], p=7·81 × 10−28). For rs62025270, the allele A associated with increased susceptibility to IPF was also associated with increased expression of AKAP13 mRNA in lung tissue from patients who had lung resection procedures (n=1111). We showed that AKAP13 is expressed in the alveolar epithelium and lymphoid follicles from patients with IPF, and AKAP13 mRNA expression was 1·42-times higher in lung tissue from patients with IPF (n=46) than that in lung tissue from controls (n=51).InterpretationAKAP13 is a Rho guanine nucleotide exchange factor regulating activation of RhoA, which is known to be involved in profibrotic signalling pathways. The identification of AKAP13 as a susceptibility gene for IPF increases the prospect of successfully targeting RhoA pathway inhibitors in patients with IPF.FundingUK Medical Research Council, National Heart, Lung, and Blood Institute of the US National Institutes of Health, Agencia Canaria de Investigación, Innovación y Sociedad de la Información, Spain, UK National Institute for Health Research, and the British Lung Foundation.

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Background The lung has a diverse microbiome that is modest in biomass. This microbiome differs in asthmatic patients compared to control subjects, but the effects of clinical characteristics on the microbial community composition and structure are not clear. Objectives We examined whether the composition and structure of the lower airway microbiome correlated with clinical characteristics of chronic, persistent asthma including airflow obstruction, use of corticosteroid medications, and presence of airway eosinophilia. Methods DNA was extracted from endobronchial brushings and bronchoalveolar lavage fluid collected from 39 asthmatic and 19 control subjects, along with negative control samples. 16S rRNA V4 amplicon sequencing was employed to compare the relative abundance of bacterial genera to clinical characteristics. Results Differential feature selection analysis revealed significant differences in microbial diversity between asthmatic and control brush and lavage samples. Lactobacillus, Pseudomonas, and Rickettsia were significantly enriched in asthmatic samples; while Prevotella, Streptococcus, and Vellonella were enriched in the control brushing samples. Generalized linear models (GLM) on brush samples demonstrated oral corticosteroid usage as an important factor affecting the relative abundance of the taxa significantly enriched in asthmatic patients. In addition, bacterial alpha-diversity in brush samples from asthmatic subjects was correlated with FEV1 and with the proportion of lavage eosinophils. Conclusion The diversity and composition of the bronchial airway microbiome of asthmatic patients is distinct from that of control, non-asthmatic patients and is influenced by worsening airflow obstruction and corticosteroid usage.

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Leukocyte telomere length (LTL), MUC5B rs35705950, and TOLLIP rs5743890 have been associated with idiopathic pulmonary fibrosis (IPF). In this observational cohort study, we assessed the associations between these genomic markers and outcomes of survival and rate of disease progression in patients with interstitial pneumonia with autoimmune features (IPAF, n=250) and connective tissue disease-associated interstitial lung disease (CTD-ILD, n=248). IPF (n=499) was used as a comparator. LTL of IPAF and CTD-ILD patients (mean age-adjusted log-transformed T/S of −0.05, [SD 0.29] and −0.04 [0.25], respectively) are longer than IPF (−0.17 [0.32]). For IPAF, LTL <10th percentile is associated with faster lung function decline compared to LTL ≥10th percentile (−6.43%/year versus −0.86%/year, p<0.0001) and worse transplant-free survival (HR 2.97 [95% CI 1.70–5.20], p=0.00014). The MUC5B rs35705950 minor allele frequency is greater for IPAF (23.2 [95% CI 18.8–28.2], p<0.0001) than controls and is associated with worse transplant-free IPAF survival (HR 1.92, [95% CI 1.18–3.13], p=0.0091). Rheumatoid arthritis-associated ILD (RA-ILD) has shorter LTL than non-RA CTD-ILD (−0.14 [SD 0.27] versus −0.01 [0.23], p=0.00055) and higher MUC5B minor allele frequency (34.6 [95% CI 24.4–46.3] versus 14.1 [9.8–20.0], p=0.00025). Neither LTL nor MUC5B are associated with transplant-free CTD-ILD survival. LTL and MUC5B minor allele frequency have different associations with lung function progression and survival for IPAF and CTD-ILD.