Interstitial Lung Diseases and Air Pollution: Narrative Review of Literature

Occupational and environmental risk factors for idiopathic pulmonary fibrosis: A case-control study

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease of unknown etiology. The aim of this study was to evaluate the environmental and occupational risk factors of IPF.

METHODS

This hospital-based, case-control study included 206 patients with IPF selected from the Seoul National University Bundang Hospital Interstitial Lung Disease registry and 167 controls without lung disease. Data on occupation, lifestyle, transportation, and types of environmental and occupational dust exposure were obtained using a questionnaire. IPF diagnosis was confirmed based on the recent guidelines, and the possibility of hypersensitivity pneumonitis was excluded. Multiple logistic regression was performed to determine the risk factors for IPF.

RESULTS

After adjusting for age and sex, ever-smokers (odds ratio [OR], 2.35; 95 % confidence interval [CI]: 1.51-3.68) and individuals who smoked more than 30 pack-years (OR, 2.79; 95%CI: 1.70-4.68) showed an increased risk for IPF. Any occupational dust exposure (adjusted OR, 2.08; 95%CI: 1.19-3.72), especially exposure to chemicals (adjusted OR, 3.52; 99%CI: 1.56-9.05), was associated with IPF after adjusting for age, sex, and smoking.

CONCLUSIONS

Smoking and occupational dust exposure are associated with an increased risk for IPF. Both factors have dose and duration-dependent relationships with the risk for IPF.

Interstitial Lung Disease Mortality Disparities Along the US-Mexico Border, 1999-2020

BACKGROUND

Optimal diagnosis and management of interstitial lung diseases (ILDs) needs access to specialized centers, frequent monitoring, and complex therapeutic options. In underprivileged areas, these necessities can often lead to barriers in delivering care.

RESEARCH QUESTION

What are the ILD mortality disparities in the regions along the US-Mexico (US-MX) border?

STUDY DESIGN AND METHODS

We obtained ILD mortality information through death certificate queries from the Centers for Disease Control and Prevention repository. Death data were adjusted for age and stratified by US-MX border regions and nonborder regions in the United States. Log-linear regression models were used to analyze mortality trends in the period from 1999 to 2020 followed by calculation of annual percentage changes (APCs). Age-adjusted mortality rates (AAMRs) were compared across cumulative and subdemographic populations.

RESULTS

ILD-related mortality among border regions (AAMR, 5.31) was higher than nonborder regions (AAMR, 4.86). Mortality within border regions remained unchanged from 1999 to 2020 (APC, 0.3; P = .269). Nonborder regions experienced a significant rise in mortality rates (APC, 2.6; P = .017) from 1999 to 2005 and remained unchanged from 2005 to 2020. Mortality was higher within both men (AAMR, 6.57) and women (AAMR, 4.36) populations among border regions compared with their nonborder counterparts (AAMR, 6.27 and 3.87, respectively). Hispanic populations among the border regions experienced higher mortality rates (AAMR, 6.15) than Hispanic populations within nonborder regions (AAMR, 5.44). Non-Hispanic populations encountered similar mortality rates between the two regions. Mortality rates among Hispanic (APC, 0.0; P = .938) and non-Hispanic (APC, 0.2; P = .531) populations in the border regions remained unchanged from 1999 to 2020.

INTERPRETATION

These results revealed ILD-related mortality disparities among the US-MX border regions, emphasizing the importance of public health measures to increase access to equitable medical care and implement targeted interventions among these vulnerable populations.

Risk factors for interstitial lung disease in rheumatoid arthritis: a cohort study from the KOBIO registry

Background

Interstitial lung disease (ILD) is a critical extra-articular manifestation of rheumatoid arthritis (RA). However, little is known about the risk factors of RA-ILD.

Objectives

Here, we examined the effect of demographic, clinical, therapeutic, and environmental factors on the incidence of ILD in RA patients using the Korean College of Rheumatology Biologics and Targeted Therapy (KOBIO) registry.

Design

We used data from the KOBIO registry, a multi-center, prospective, observational cohort that included RA patients in South Korea.

Methods

RA patients who used biologic or targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) or conventional synthetic (cs)DMARDs, and were enrolled in the KOBIO registry, were examined. Demographic, clinical, and radiographic characteristics, as well as medications, were recorded at baseline and annually thereafter. Kaplan-Meier curves and the log-rank test were used to compare the incidence of ILD between RA patients taking different b/tsDMARDs. Hazard ratios (HRs) were calculated by Cox regression analyses.

Results

In total, 2492 patients (1967 in the b/tsDMARDs group and 525 in the csDMARDs group) were analyzed. The b/tsDMARDs group showed longer disease duration, higher erythrocyte sedimentation rate/C-reactive protein, and higher disease activity score-28 (DAS28) than the csDMARDs group. The incidence of ILD was significantly higher in those taking tumor necrosis factor inhibitors and abatacept than in those taking csDMARDs (log ranked p < 0.001). Multivariate Cox regression analysis identified older age (HR = 1.057, p = 0.001), male sex (HR = 2.824, p = 0.007), time-averaged DAS28 (HR = 2.241, p < 0.001), and rheumatoid factor titer (HR = 1.009, p = 0.007) as having a significantly increased HR for ILD occurrence.

Conclusion

ILD is a rare but critical extra-articular symptom of RA patients. Therefore, RA patients with the above risk factors should be monitored carefully for ILD development.

Interstitial Lung Disease and Sarcoidosis

Interstitial lung disease (ILD), a clinically recognized group of diseases resulting in pulmonary fibrosis, affects up to 200 individuals per 100,000 in the United States. Sarcoidosis has a wide range of clinical manifestations including pulmonary fibrosis. Health disparities are prevalent in both ILD and sarcoidosis around socioeconomic status, race, gender, and geographic location. This review outlines the known health disparities, discusses possible determinants of disparities, and outlines a path to achieve equity in ILD and sarcoidosis.

Childhood Interstitial Lung Disease

Childhood interstitial lung disease (chILD) is a heterogeneous group of diseases with various clinical and imaging findings. The incidence and prevalence have increased in recent years, probably due to better comprehension of these rare diseases and increased awareness among physicians. chILDs present with nonspecific pulmonary symptoms, such as tachypnea, hypoxemia, cough, rales, and failure to thrive. Unnecessary invasive procedures can be avoided if specific mutations are detected through genetic examinations or if typical imaging patterns are recognized on computed tomography. Disease knowledge and targeted therapies are improving through international collaboration. Pulmonary involvement in systemic diseases is not uncommon. Pulmonary involvement may be the first finding in connective tissue diseases. This review aims to present a systematic patient-targeted approach to the diagnosis of chILD.

The "Elastic Perspective" of SARS-CoV-2 Infection and the Role of Intrinsic and Extrinsic Factors

Elastin represents the structural component of the extracellular matrix providing elastic recoil to tissues such as skin, blood vessels and lungs. Elastogenic cells secrete soluble tropoelastin monomers into the extracellular space where these monomers associate with other matrix proteins (e.g., microfibrils and glycoproteins) and are crosslinked by lysyl oxidase to form insoluble fibres. Once elastic fibres are formed, they are very stable, highly resistant to degradation and have an almost negligible turnover. However, there are circumstances, mainly related to inflammatory conditions, where increased proteolytic degradation of elastic fibres may lead to consequences of major clinical relevance. In severely affected COVID-19 patients, for instance, the massive recruitment and activation of neutrophils is responsible for the profuse release of elastases and other proteolytic enzymes which cause the irreversible degradation of elastic fibres. Within the lungs, destruction of the elastic network may lead to the permanent impairment of pulmonary function, thus suggesting that elastases can be a promising target to preserve the elastic component in COVID-19 patients. Moreover, intrinsic and extrinsic factors additionally contributing to damaging the elastic component and to increasing the spread and severity of SARS-CoV-2 infection are reviewed.

Long-term personal air pollution exposure and risk for acute exacerbation of idiopathic pulmonary fibrosis

BACKGROUND

Urban air pollution is involved in the progress of idiopathic pulmonary fibrosis (IPF). Its potential role on the devastating event of Acute Exacerbation of IPF (AE-IPF) needs to be clarified. This study examined the association between long-term personal air pollution exposure and AE- IPF risk taking into consideration inflammatory mediators and telomere length (TL).

METHODS

All consecutive IPF-patients referred to our Hospital from October 2013-June 2019 were included. AE-IPF events were recorded and inflammatory mediators and TL measured. Long-term personal air pollution exposures were assigned to each patient retrospectively, for O₃, NO₂, PM_2.5 [and PM₁₀, based on geo-coded residential addresses. Logistic regression models assessed the association of air pollutants' levels with AE-IPF and inflammatory mediators adjusting for potential confounders.

RESULTS

118 IPF patients (mean age 72 ± 8.3 years) were analyzed. We detected positive significant associations between AE-IPF and a 10 μg/m³ increase in previous-year mean level of NO₂ (OR = 1.52, 95%CI:1.15-2.0, p = 0.003), PM_2.5 (OR = 2.21, 95%CI:1.16-4.20, p = 0.016) and PM₁₀ (OR = 2.18, 95%CI:1.15-4.15, p = 0.017) independent of age, gender, smoking, lung function and antifibrotic treatment. Introduction of TL in all models of a subgroup of 36 patients did not change the direction of the observed associations. Finally, O₃ was positively associated with %change of IL-4 (p = 0.014) whilst PM_2.5, PM₁₀ and NO₂ were inversely associated with %changes of IL-4 (p = 0.003, p = 0.003, p = 0.032) and osteopontin (p = 0.013, p = 0.013, p = 0.085) respectively.

CONCLUSIONS

Long-term personal exposure to increased concentrations of air pollutants is an independent risk factor of AE-IPF. Inflammatory mediators implicated in lung repair mechanisms are involved.