Contemporary Concise Review 2021: Interstitial lung disease

Progressive pulmonary fibrosis (PPF): Estimation of incidence and treatment rates in Japan using a claims database

BACKGROUND

Interstitial lung diseases (ILDs) are a heterogeneous group of disorders, a subset of which develop progressive pulmonary fibrosis (PPF). There is little information on the epidemiology and treatment of PPFs in Japan. This retrospective cohort study estimated the incidence probability of progression to PPFs in patients with fibrosing ILDs other than idiopathic pulmonary fibrosis in a real-world Japanese setting. Management procedures and treatment patterns were also quantified.

METHODS

Data were extracted from the Medical Data Vision database from 01-Jan-2012 to 28-May-2020, comprising a 6.91-year patient identification period, 1-year pre-index period, and post-index period. The primary outcome was the cumulative incidence probability of progression to PPF up to 24 months. Subgroup analyses were performed by the presence/absence of connective tissue disease-ILD and by pre-specified ILD clinical diagnosis.

RESULTS

Of the 34,960 eligible patients (mean age: 71.1 years, males: 52.5%), 14,580 (41.7%) progressed to PPF. The 24-month incidence probability of progression to PPF was 39.5%. A relatively comparable percentage of patients progressed across all ILD subtypes. Oral corticosteroids and tacrolimus were the most common therapies during the pre- and post-index periods. Treatment rates were very low in the post-index period.

CONCLUSIONS

This is the first claims database study to estimate the incidence probability of progression to PPF in Japan. Progression appeared common in patients with chronic fibrosing ILDs, with comparable percentages of patients across all subtypes developing PPF at 2 years. Future studies should assess the impact of regular monitoring and early intervention on treating fibrotic ILDs and preventing progression.

Metabolism-driven glycosylation represents therapeutic opportunities in interstitial lung diseases

Metabolic changes are coupled with alteration in protein glycosylation. In this review, we will focus on macrophages that are pivotal in the pathogenesis of pulmonary fibrosis and sarcoidosis and thanks to their adaptable metabolism are an attractive therapeutic target. Examples presented in this review demonstrate that protein glycosylation regulates metabolism-driven immune responses in macrophages, with implications for fibrotic processes and granuloma formation. Targeting proteins that regulate glycosylation, such as fucosyltransferases, neuraminidase 1 and chitinase 1 could effectively block immunometabolic changes driving inflammation and fibrosis, providing novel avenues for therapeutic interventions.

The gene expression of CALD1, CDH2, and POSTN in fibroblast are related to idiopathic pulmonary fibrosis

Introduction

Idiopathic pulmonary fibrosis (IPF) is characterized by progressive lung dysfunction due to excessive collagen production and tissue scarring. Despite recent advancements, the molecular mechanisms remain unclear.

Methods

RNA sequencing identified 475 differentially expressed genes (DEGs) in the TGF-β1-induced primary lung fibrosis model. Gene expression chips GSE101286 and GSE110147 from NCBI gene expression omnibus (GEO) database were analyzed using GEO2R, revealing 94 DEGs in IPF lung tissue samples. The gene ontology (GO) and pathway enrichment, Protein-protein interaction (PPI) network construction, and Maximal Clique Centrality (MCC) scoring were performed. Experimental validation included RT-qPCR, Immunohistochemistry (IHC), and Western Blot, with siRNA used for gene knockdown. A co-expression network was constructed by GeneMANIA.

Results

GO enrichment highlighted significant enrichment of DEGs in TGF-β cellular response, connective tissue development, extracellular matrix components, and signaling pathways such as the AGE-RAGE signaling pathway and ECM-receptor interaction. PPI network analysis identified hub genes, including FN1, COL1A1, POSTN, KIF11, and ECT2. CALD1 (Caldesmon 1), CDH2 (Cadherin 2), and POSTN (Periostin) were identified as dysregulated hub genes in both the RNA sequencing and GEO datasets. Validation experiments confirmed the upregulation of CALD1, CDH2, and POSTN in TGF-β1-treated fibroblasts and IPF lung tissue samples. IHC experiments probed tissue-level expression patterns of these three molecules. Knockdown of CALD1, CDH2, and POSTN attenuated the expression of fibrotic markers (collagen I and α-SMA) in response to TGF-β1 stimulation in primary fibroblasts. Co-expression analysis revealed interactions between hub genes and predicted genes involved in actin cytoskeleton regulation and cell-cell junction organization.

Conclusions

CALD1, CDH2, and POSTN, identified as potential contributors to pulmonary fibrosis, present promising therapeutic targets for IPF patients.

Role of Telomere Length in Survival of Patients with Idiopathic Pulmonary Fibrosis and Other Interstitial Lung Diseases

Interstitial lung diseases (ILDs) constitute a group of more than 200 disorders, with idiopathic pulmonary fibrosis (IPF) being one of the most frequent. Telomere length (TL) shortening causes loss of function of the lung parenchyma. However, little is known about its role as a prognostic factor in ILD patients. With the aim of investigating the role of TL and telomerase activity in the prognosis of patients affected by ILDs, we analysed lung tissue samples from 61 patients. We measured relative TL and telomerase activity by conventional procedures. Both clinical and molecular parameters were associated with overall survival by the Kaplan-Meier method. Patients with IPF had poorer prognosis than patients with other ILDs (p = 0.034). When patients were classified according to TL, those with shortened telomeres reported lower overall survival (p = 0.085); differences reached statistical significance after excluding ILD patients who developed cancer (p = 0.021). In a Cox regression analysis, TL behaved as a risk-modifying variable for death associated with rheumatic disease (RD) co-occurrence (p = 0.029). Also, in patients without cancer, ferritin was significantly increased in cases with RD and IPF co-occurrence (p = 0.032). In relation to telomerase activity, no significant differences were detected. In conclusion, TL in lung tissue emerges as a prognostic factor in ILD patients. Specifically, in cases with RD and IPF co-occurrence, TL can be considered as a risk-modifying variable for death.

Systemic Determinants of Exercise Intolerance in Patients With Fibrotic Interstitial Lung Disease and Severely Impaired DLCO

BACKGROUND

The precise mechanisms driving poor exercise tolerance in patients with fibrotic interstitial lung diseases (fibrotic ILDs) showing a severe impairment in single-breath lung diffusing capacity for carbon monoxide (DLCO < 40% predicted) are not fully understood. Rather than only reflecting impaired O2 transfer, a severely impaired DLCO may signal deranged integrative physiologic adjustments to exercise that jointly increase the burden of exertional symptoms in fibrotic ILD.

METHODS

Sixty-seven subjects (46 with idiopathic pulmonary fibrosis, 24 showing DLCO < 40%) and 22 controls underwent pulmonary function tests and an incremental cardiopulmonary exercise test with serial measurements of operating lung volumes and 0-10 Borg dyspnea and leg discomfort scores.

RESULTS

Subjects from the DLCO < 40% group showed lower spirometric values, more severe restriction, and lower alveolar volume and transfer coefficient compared to controls and participants with less impaired DLCO (P < .05). Peak work rate was ∼45% (vs controls) and ∼20% (vs DLCO > 40%) lower in the former group, being associated with lower (and flatter) O2 pulse, an earlier lactate (anaerobic) threshold, heightened submaximal ventilation, and lower SpO2 . Moreover, critically high inspiratory constrains were reached at lower exercise intensities in the DLCO < 40% group (P < .05). In association with the greatest leg discomfort scores, they reported the highest dyspnea scores at a given work rate. Between-group differences lessened or disappeared when dyspnea intensity was related to indexes of increased demand-capacity imbalance, that is, decreasing submaximal, dynamic ventilatory reserve, and inspiratory reserve volume/total lung capacity (P > .05).

CONCLUSIONS

A severely reduced DLCO in fibrotic ILD signals multiple interconnected derangements (cardiovascular impairment, an early shift to anaerobic metabolism, excess ventilation, inspiratory constraints, and hypoxemia) that ultimately lead to limiting respiratory (dyspnea) and peripheral (leg discomfort) symptoms. DLCO < 40%, therefore, might help in clinical decision-making to indicate the patient with fibrotic ILD who might derive particular benefit from pharmacologic and non-pharmacologic interventions aimed at lessening these systemic abnormalities.

Ginsenosides: a potential natural medicine to protect the lungs from lung cancer and inflammatory lung disease

Lung cancer is the malignancy with the highest morbidity and mortality. Additionally, pulmonary inflammatory diseases, such as pneumonia, acute lung injury, chronic obstructive pulmonary disease (COPD), and pulmonary fibrosis (PF), also have high mortality rates and can promote the development and progression of lung cancer. Unfortunately, available treatments for them are limited, so it is critical to search for effective drugs and treatment strategies to protect the lungs. Ginsenosides, the main active components of ginseng, have been shown to have anti-cancer and anti-inflammatory activities. In this paper, we focus on the beneficial effects of ginsenosides on lung diseases and their molecular mechanisms. Firstly, the molecular mechanism of ginsenosides against lung cancer was summarized in detail, mainly from the points of view of proliferation, apoptosis, autophagy, angiogenesis, metastasis, drug resistance and immunity. In in vivo and in vitro lung cancer models, ginsenosides Rg3, Rh2 and CK were reported to have strong anti-lung cancer effects. Then, in the models of pneumonia and acute lung injury, the protective effect of Rb1 was particularly remarkable, followed by Rg3 and Rg1, and its molecular mechanism was mainly associated with targeting NF-κB, Nrf2, MAPK and PI3K/Akt pathways to alleviate inflammation, oxidative stress and apoptosis. Additionally, ginsenosides may also have a potential health-promoting effect in the improvement of COPD, asthma and PF. Furthermore, to overcome the low bioavailability of CK and Rh2, the development of nanoparticles, micelles, liposomes and other nanomedicine delivery systems can significantly improve the efficacy of targeted lung cancer treatment. To conclude, ginsenosides can be used as both anti-lung cancer and lung protective agents or adjuvants and have great potential for future clinical applications.

Association of the 6-minute walking test ratio and difference with pulmonary function in patients with interstitial lung disease

OBJECTIVES

To examine the associations between 6-minute walk test (6MWT) and lung functions, blood gas analysis findings, fractional exhaled nitric oxide (FeNO), and hospital stay in interstitial lung disease (ILD).

METHODS

The present retrospective study included patients hospitalized in Beijing Hospital of Traditional Chinese Medicine, Capital Medical University between September 2018 and December 2019. The outcomes included the difference between the actual and predicted 6MWT values (6MWT difference) and the ratio of the actual to predicted 6MWT value (6MWT ratio).

RESULTS

This study included 137 patients. The predicted 6MWT value was 519±61 m and the actual 6MWT value was 449 (196.5,694)m. The 6MWT ratio was 84.7±177.6 and 6MWT difference was 73.9±95.1 m. Fractional exhaled nitric oxide (FeNO) (β= -2.157, standard error [SE]=0.836, p=0.014) and diffusing capacity of the lungs for carbon monoxide (DLCO) (β= -22.528, SE=7.48, p=0.004) had independent associations with 6MWT difference. The FeNO (β=0.403, SE=0.163, p=0.018) and DLCO (β=4.355, SE=1.458, p=0.005) had independent associations with 6MWT ratio.

CONCLUSION

In ILD, 6MWT difference and 6MWT ratio were associated with FeNO and DLCO. The 6MWT value was not associated with hospital stay. Therefore, the 6MWT might be a surrogate marker of pulmonary function in clinical ILD.

Physiological underpinnings of exertional dyspnoea in mild fibrosing interstitial lung disease

The functional disturbances driving "out-of-proportion" dyspnoea in patients with fibrosing interstitial lung disease (f-ILD) showing only mild restrictive abnormalities remain poorly understood. Eighteen patients (10 with idiopathic pulmonary fibrosis) showing preserved spirometry and mildly reduced total lung capacity (≥70% predicted) and 18 controls underwent an incremental cardiopulmonary exercise test with measurements of operating lung volumes and Borg dyspnoea scores. Patients' lower exercise tolerance was associated with higher ventilation (V̇_E)/carbon dioxide (V̇CO₂) compared with controls (V̇_E/V̇CO₂ nadir=35 ± 3 versus 29 ± 2; p < 0.001). Patients showed higher tidal volume/inspiratory capacity and lower inspiratory reserve volume at a given exercise intensity, reporting higher dyspnoea scores as a function of both work rate and V̇_E. Steeper dyspnoea-work rate slopes were associated with lower lung diffusing capacity, higher V̇_E/V̇CO₂, and lower peak O₂ uptake (p < 0.05). Heightened ventilatory demands in the setting of progressively lower capacity for tidal volume expansion on exertion largely explain higher-than-expected dyspnoea in f-ILD patients with largely preserved dynamic and "static" lung volumes at rest.