Mapping IPF helps identify geographic regions at higher risk for disease development and potential triggers

Epidemiology of idiopathic pulmonary fibrosis in central and Western Pennsylvania

BACKGROUND/RATIONALE

Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive disease of unknown origin. Establishing the epidemiology of IPF has been challenging due to diagnostic complexity, poor survival, low prevalence, and heterogeneity of ascertainment methodologies.

OBJECTIVES

This research aimed to estimate the rates of IPF in central and western Pennsylvania and to pilot the use of capture recapture (CR) methods to estimate the disease incidence.

METHODS

We identified adults ≥ 30 years old diagnosed with IPF (by ICD-9/10 coding) between 2013 to 2021 from two health systems (UPMC Health System and Penn State Health) participating in the PaTH Clinical Research Network. We extracted information on patients' sex, race, date of birth and 3-digit zip code from electronic health records (EHR). Incidence rate of IPF among Pennsylvania residents was calculated using three case definitions (broad and two restricted) and piloted the use of CR in estimating IPF incidence.

RESULTS

IPF incidence rates were 8.42, 6.95 and 4.4 per 100,000 person-years for the unrestricted (n = 3148), partially restricted (n = 2598) and fully restricted (n = 1661) samples, respectively. Low case overlap between two sites resulted in a highly inflated estimate of IPF incidence, using the CR methodology.

CONCLUSIONS

The rate of IPF in central and western Pennsylvania was similar to previously published statistics. The application of CR to IPF epidemiology could be further investigated in health systems with greater overlap of patients utilizing more than one system.

Diagnostic and prognostic implications of family history of fibrotic interstitial lung diseases

BACKGROUND

Patients with familial fibrotic interstitial lung disease (ILD) experience worse survival than patients with sporadic disease. Current guidelines do not consider family aggregation or genetic information in the diagnostic algorithm for idiopathic pulmonary fibrosis or other fibrotic ILDs. Better characterizing familial cases could help in diagnostic and treatment decision-making.

METHODS

This retrospective cohort study included 222 patients with fibrotic ILD (104 familial and 118 sporadic) from Bellvitge University Hospital. Clinical, radiological, pulmonary functional tests (PFT), and histological evaluations were performed at diagnosis and follow-up. Telomere shortening and disease-associated variants (DAVs) in telomerase-related genes were analysed in familial patients and sporadic patients with telomeric clinical signs. Primary outcomes were the presence of a UIP histological pattern and disease progression.

RESULTS

Patients with idiopathic pulmonary fibrosis (IPF) (52%), fibrotic hypersensitivity pneumonitis (23%), and other fibrotic ILDs (25%) were included. 42% of patients underwent lung biopsy. Patients with family aggregation were younger and less frequently associated comorbidities, male sex, and smoking history. However, usual interstitial pneumonia (UIP) was more frequent on pathology (p = 0.005; OR 3.37), especially in patients with indeterminate or non-UIP radiological patterns. Despite similar PFT results at diagnosis, familial patients were more likely to present with progressive disease (p = 0.001; OR 3.75). Carrying a DAV increased the risk of fibrotic progression in familial and sporadic patients (p = 0.029, OR 5.01).

DISCUSSION

Familial patients diagnosed with different fibrotic ILDs were more likely to exhibit a histological UIP pattern and disease progression than sporadic patients, independent of radiological findings and pulmonary function at diagnosis.

CONCLUSION

Considering the diagnostic likelihood of the histological UIP pattern and disease outcome, the presence of family aggregation would be useful in the decision making of multidisciplinary committees.

Association between high levels of nitrogen dioxide and increased cumulative incidence of lung cancer in patients with idiopathic pulmonary fibrosis

BACKGROUND

Lung cancer is a fatal complication of idiopathic pulmonary fibrosis (IPF) with a poor prognosis. However, the association between individual exposure to air pollutants and lung cancer development in patients with IPF is unknown. This study aimed to assess the effect of individual exposure to nitrogen dioxide (NO2) on lung cancer development in patients with IPF.

METHODS

We enrolled 1085 patients from an IPF cohort in the Republic of Korea (mean age 65.6 years, males 80.6%). We estimated individual-level long-term exposures to NO2 at the patients' residential addresses using a national-scale exposure prediction model based on data from air quality regulatory monitoring stations. To evaluate the association between NO2 levels and lung cancer development in IPF, we used an individual- and area-level covariates adjusted model as our primary model.

RESULTS

The estimated average annual NO2 concentration was 23.1 ppb. During a median follow-up of 4.3 years, 86 patients (7.9%) developed lung cancer. NO2 concentration was associated with lung cancer development in an unadjusted model (HR 1.219; p=0.042), while a marginal association was found in the primary model (HR 1.280; p=0.084). When NO2 concentration was stratified by the median value (21.0 ppb), exposure to high NO2 levels (≥21.0 ppb) was associated with a 2.0-fold increase in the risk of lung cancer development (HR 2.023; p=0.047) in the primary model.

CONCLUSION

Individual exposure to high NO2 levels may increase the risk of lung cancer development in patients with IPF.

Effects of indoor air pollution on clinical outcomes in patients with interstitial lung disease: protocol of a multicentre prospective observational study

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive fibrosing interstitial lung disease with a poor prognosis. While there is evidence suggesting that outdoor air pollution affects the clinical course of IPF, the impact of indoor air pollution on patients with IPF has not been extensively studied. Therefore, this prospective multicentre observational study aims to investigate the association between indoor air pollution and clinical outcomes in patients with IPF.

METHODS AND ANALYSIS

This study enrolled 140 patients with IPF from 12 medical institutes in the Seoul and Metropolitan areas of the Republic of Korea. Over the course of 1 year, participants visited the institutes every 3 months, during which their clinical data and blood samples were collected. Additionally, indoor exposure to particulate matter ≤2.5 µm (PM2.5) was measured using MicroPEM (RTI International, Research Triangle Park, North Carolina, USA) in each participant's house for 5 days every 3 months. Lung function was assessed using both site spirometry at each institution and portable spirometry at each participant's house every 3 months. The study will analyse the impact of indoor PM2.5 on clinical outcomes, including mortality, acute exacerbation, changes in lung function and health-related quality of life, in the participants. This study represents the first attempt to evaluate the influence of indoor air pollution on the prognosis of patients with IPF.

ETHICS AND DISSEMINATION

This study has received approval from the institutional review board of all participating institutions, including Asan Medical Center, Seoul, Republic of Korea (2021-0072).

TRIAL REGISTRATION NUMBER

KCT0006217.

The impact of air pollution on interstitial lung disease: a systematic review and meta-analysis

Introduction

There is a growing body of evidence suggesting a causal relationship between interstitial lung disease (ILD) and air pollution, both for the development of the disease, and driving disease progression. We aim to provide a comprehensive literature review of the association between air pollution, and ILD, including idiopathic pulmonary fibrosis (IPF).

Methods

We systematically searched from six online database. Two independent authors (DL and CF) selected studies and critically appraised the risk of bias using the Newcastle-Ottawa Scale (NOS). Findings are presented through a narrative synthesis and meta-analysis. Meta-analyses were performed exclusively when there was a minimum of three studies examining identical pollutant-health outcome pairs, all evaluating equivalent increments in pollutant concentration, using a random effects model.

Results

24 observational studies conducted in 13 countries or regions were identified. Pollutants under investigation encompassed ozone (O3), nitrogen dioxide (NO2), Particulate matter with diameters of 10 micrometers or less (PM10) and 2.5 micrometers or less (PM2.5), sulfur dioxide (SO2), carbon monoxide (CO), nitric oxide (NO) and nitrogen oxides (NOx). We conducted meta-analyses to assess the estimated Risk Ratios (RRs) for acute exacerbations (AE)-IPF in relation to exposure to every 10 μg/m3 increment in air pollutant concentrations, including O3, NO2, PM10, and PM2.5. The meta-analysis revealed a significant association between the increased risk of AE-IPF in PM2.5, yielding RR 1.94 (95% CI 1.30-2.90; p = 0.001). Findings across all the included studies suggest that increased exposure to air pollutants may be linked to a range of health issues in individuals with ILDs.

Conclusion

A scarcity of available studies on the air pollutants and ILD relationship underscores the imperative for further comprehensive research in this domain. The available data suggest that reducing levels of PM2.5 in the atmosphere could potentially reduce AE frequency and severity in ILD patients.

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.

The association between air pollution and the severity at diagnosis and progression of systemic sclerosis-associated interstitial lung disease: results from the retrospective ScleroPol study

OBJECTIVE

To investigate the association of air pollution exposure with the severity of interstitial lung disease (ILD) at diagnosis and ILD progression among patients with systemic sclerosis (SSc)-associated ILD.

METHODS

We conducted a retrospective two-center study of patients with SSc-associated ILD diagnosed between 2006 and 2019. Exposure to the air pollutants particulate matter of up to 10 and 2.5 µm in diameter (PM₁₀, PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃) was assessed at the geolocalization coordinates of the patients' residential address. Logistic regression models were used to evaluate the association between air pollution and severity at diagnosis according to the Goh staging algorithm, and progression at 12 and 24 months.

RESULTS

We included 181 patients, 80% of whom were women; 44% had diffuse cutaneous scleroderma, and 56% had anti-topoisomerase I antibodies. ILD was extensive, according to the Goh staging algorithm, in 29% of patients. O₃ exposure was associated with the presence of extensive ILD at diagnosis (adjusted OR: 1.12, 95% CI 1.05-1.21; p value = 0.002). At 12 and 24 months, progression was noted in 27/105 (26%) and 48/113 (43%) patients, respectively. O₃ exposure was associated with progression at 24 months (adjusted OR: 1.10, 95% CI 1.02-1.19; p value = 0.02). We found no association between exposure to other air pollutants and severity at diagnosis and progression.

CONCLUSION

Our findings suggest that high levels of O₃ exposure are associated with more severe SSc-associated ILD at diagnosis, and progression at 24 months.

Nitrogen dioxide increases the risk of disease progression in idiopathic pulmonary fibrosis

BACKGROUND AND OBJECTIVE

Air pollution affects clinical course and prognosis of idiopathic pulmonary fibrosis (IPF). However, the effect of individual exposure to air pollutants on disease progression is unclear. We aimed to identify the effect of individual exposure to nitrogen dioxide (NO₂ ) and particulate matter (aerodynamic diameter ≤ 10 μm [PM₁₀ ]) on disease progression in patients with IPF.

METHODS

The serial lung function data of 946 IPF patients (mean age: 65.4 years, male: 80.9%) were analysed. Individual-level long-term exposures to NO₂ and PM₁₀ at the residential addresses of patients were estimated using a national-scale exposure prediction model, constructed based on air quality regulatory monitoring data. Progression was defined as a relative decline (≥10%) in forced vital capacity. Individual- and area-level covariates were adjusted in the primary analysis model.

RESULTS

Overall, 547 patients (57.8%) experienced progression during a median follow-up of 1.0 year (interquartile range: 0.4-2.6 years). In the primary model, a 10-ppb increase in NO₂ concentration was associated with a 10.5% increase in the risk of progression (hazard ratio [HR] = 1.105; 95% CI = 1.000-1.219) in patients with IPF. There was also an increasing trend of progression in patients with IPF according to the second to fourth quartiles of NO₂ (Q2 [HR = 1.299; 95% CI = 0.972-1.735], Q3 [1.409; 1.001-1.984], Q4 [1.598; 1.106-2.310]) compared to the first quartile. We found no association between PM₁₀ and progression in IPF patients.

CONCLUSION

Our data suggest that increased individual exposure to NO₂ can increase the risk of progression in patients with IPF.

Russian Registry of Idiopathic Pulmonary Fibrosis: Clinical Features, Treatment Management, and Outcomes

A registry of patients with idiopathic pulmonary fibrosis (IPF) was founded in Russia in 2016. The aim of this study was to analyze the demographic, clinical, functional, radiological, and morphological data of the patients included in this registry.

METHODS

This was a prospective multicenter, observational, non-interventional study. Patients' risk factors, demographics, clinical data, results of high-resolution computed tomography (HRCT) of the chest and pulmonary function testing, and lung tissue biopsy findings were analyzed. We also analyzed the exercise tolerance (6-min walking test) of patients, serological markers of systemic connective tissue diseases, treatment, clinical course, and outcomes of the disease. Multidisciplinary discussion (MDD) was used as needed.

RESULTS

One thousand three hundred and fifty-three patients were included in the registry from 2016 to 2020. The mean age was 64.4 ± 10.7 years, most patients were active smokers or ex-smokers. Antifibrotic therapy was administered to 90 of 948 patients (9.5%). Since starting the registry in 2016, the incidences of IPF have increased and the time period from manifestation of the disease to making the diagnosis has shortened, the number of patients on antifibrotic therapy has increased and the number of patients taking systemic steroids decreased.

CONCLUSION

The registry of patients with IPF was helpful to improve IPF diagnosis and to implement antifibrotic agents in clinical practice. Further analysis of the clinical course and prognostic markers of IPF in the Russian population is needed. An analysis of the long-term efficacy of antifibrotic therapy in this population is also important.

The proteasome-dependent degradation of ALKBH5 regulates ECM deposition in PM2.5 exposure-induced pulmonary fibrosis of mice

Long-term inhalation of fine particulate matter (PM_2.5) can cause serious effects on the respiratory system. It might be attributed to the fact that PM_2.5 could directly enter and deposit in lung tissues. We established models of PM_2.5 exposure in vivo and in vitro to explore the adverse effects of ambient PM_2.5 on pulmonary and its potential pathogenic mechanisms. Our results showed that PM_2.5 exposure promoted the deposition of ECM and the increased stiffness of the lungs, and then led to pulmonary fibrosis in time- and dose- dependent manners. Pulmonary function test showed restrictive ventilation function in mice after PM_2.5 exposure. After PM_2.5 exposure, ALKBH5 was recognized by TRIM11 and then degraded through the proteasome pathway. ALKBH5 deficiency (ALKBH5^-/-) aggravated restrictive ventilatory disorder and promoted ECM deposition in lungs of mice induced by PM2.5. And the YAP1 signaling pathway was more activated in ALKBH5^-/- than WT mice after PM_2.5 exposure. In consequence, decreased ALKBH5 protein levels regulated miRNAs and then the miRNAs-targeted YAP1 signaling was activated to promote pulmonary fibrosis induced by PM_2.5.

Harnessing PM2.5 Exposure Data to Predict Progression of Fibrotic Interstitial Lung Diseases Based on Telomere Length

Cross-analysis of clinical and pollution factors could help calculate the risk of fibrotic interstitial lung disease (ILD) development and progression. The intent of this study is to build a body of knowledge around early detection and diagnosis of lung disease, harnessing new data sets generated for other purposes. We cross-referenced exposure levels to particulate matter 2.5 (PM2.5) with telomere length of a cohort of 280 patients with fibrotic ILD to weigh impact and associations. There was no linear correlation between PM2.5 and telomere length in our data sets, as the value of the correlation coefficient was 0.08. This exploratory study offers additional insights into methodologies for investigating the development and prognosis of pulmonary fibrosis.

Contemporary Concise Review 2021: Interstitial lung disease

The last 2 years have presented previously unforeseen challenges in pulmonary medicine. Despite the significant impact of the SARS‐CoV‐2 pandemic on patients, clinicians and communities, advances in the care and understanding of interstitial lung disease (ILD) continued unabated. Recent studies have led to improved guidelines, better understanding of the role for antifibrotics in fibrosing ILDs, prognostic indicators and novel biomarkers. In this concise contemporary review, we summarize many of the important studies published in 2021, highlighting their relevance and impact to the management and knowledge of ILD.

Biomarkers for the adverse effects on respiratory system health associated with atmospheric particulate matter exposure

Large amounts of epidemiological evidence have confirmed the atmospheric particulate matter (PM_2.5) exposure was positively correlated with the morbidity and mortality of respiratory diseases. Nevertheless, its pathogenesis remains incompletely understood, probably resulting from the activation of oxidative stress, inflammation, altered genetic and epigenetic modifications in the lung upon PM_2.5 exposure. Currently, biomarker investigations have been widely used in epidemiological and toxicological studies, which may help in understanding the biologic mechanisms underlying PM_2.5-elicited adverse health outcomes. Here, the emerging biomarkers to indicate PM_2.5-respiratory system interactions were summarized, primarily related to oxidative stress (ROS, MDA, GSH, etc.), inflammation (Interleukins, FE_NO, CC16, etc.), DNA damage (8-OHdG, γH2AX, OGG1) and also epigenetic modulation (DNA methylation, histone modification, microRNAs). The identified biomarkers shed light on PM_2.5-elicited inflammation, fibrogenesis and carcinogenesis, thus may favor more precise interventions in public health. It is worth noting that some inconsistent findings may possibly relate to the inter-study differentials in the airborne PM_2.5 sample, exposure mode and targeted subjects, as well as methodological issues. Further research, particularly by -omics technique to identify novel, specific biomarkers, is warranted to illuminate the causal relationship between PM_2.5 pollution and deleterious lung outcomes.

Molecular Mechanisms and Cellular Contribution from Lung Fibrosis to Lung Cancer Development

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrosing interstitial lung disease (ILD) of unknown aetiology, with a median survival of 2-4 years from the time of diagnosis. Although IPF has unknown aetiology by definition, there have been identified several risks factors increasing the probability of the onset and progression of the disease in IPF patients such as cigarette smoking and environmental risk factors associated with domestic and occupational exposure. Among them, cigarette smoking together with concomitant emphysema might predispose IPF patients to lung cancer (LC), mostly to non-small cell lung cancer (NSCLC), increasing the risk of lung cancer development. To this purpose, IPF and LC share several cellular and molecular processes driving the progression of both pathologies such as fibroblast transition proliferation and activation, endoplasmic reticulum stress, oxidative stress, and many genetic and epigenetic markers that predispose IPF patients to LC development. Nintedanib, a tyrosine-kinase inhibitor, was firstly developed as an anticancer drug and then recognized as an anti-fibrotic agent based on the common target molecular pathway. In this review our aim is to describe the updated studies on common cellular and molecular mechanisms between IPF and lung cancer, knowledge of which might help to find novel therapeutic targets for this disease combination.

Astragaloside IV Protects from PM2.5-Induced Lung Injury by Regulating Autophagy via Inhibition of PI3K/Akt/mTOR Signaling in vivo and in vitro

Introduction

Prolonged exposure to air polluted with airborne fine particulate matter (PM2.5) can increase respiratory disease risk. Astragaloside IV (AS-IV) is one of the main bioactive substances in the traditional Chinese medicinal herb, Astragalus membranaceus Bunge. AS-IV has numerous pharmacological properties; whereas there are few reports on the prevention of PM2.5-induced lung injury by AS-IV through modulation of the autophagic pathway. This study aimed to investigate the protective effects and the underlying mechanisms of AS-IV in PM2.5-induced lung injury rats and rat alveolar macrophages (NR8383 cells).

Methods

The pneumotoxicity model was established by intratracheal injection of PM2.5 in rats, and PM2.5 challenge in NR8383 cells. The severity of lung injury was evaluated by wet weight to dry weight ratio and McGuigan pathology scoring. Inflammatory factors and oxidative stress were detected through ELISA. The expressions of p-PI3K, p-Akt, and p-mTOR proteins were analyzed by immunohistochemistry. Immunofluorescence and transmission electron microscopy were used to detect autophagosomes. The expressions of autophagy marker protein (LC3B and p62), PI3K/Akt/mTOR signaling and NF-κB translocation were detected by Western blot in lung tissue and NR8383 cells.

Results

After PM2.5 stimulation, rats showed severe inflammation and oxidative stress, along with inhibition of autophagy in lung tissue. AS-IV not only decreased pulmonary inflammation and oxidative stress by inhibiting nuclear factor kappa B translocation, but also regulated autophagy by inhibiting PI3K/Akt/mTOR signaling. After treatment with 3-methyladenine (a classic PI3K inhibitor, blocking the formation of autophagosomes), the protective effect of AS-IV on PM2.5-induced lung injury was further strengthened. In parallel, using Western blot, immunohistochemistry, and transmission electron microscopy, we demonstrated that AS-IV restore autophagic flux mainly through regulating the degradation of autophagosomes rather than suppressing the formation in vivo and in vitro.

Conclusion

Our data indicated that AS-IV protects from PM2.5-induced lung injury in vivo and in vitro by inhibiting the PI3K/Akt/mTOR pathway to regulate autophagy and inflammation.

Dissecting the Role of Mesenchymal Stem Cells in Idiopathic Pulmonary Fibrosis: Cause or Solution

Idiopathic pulmonary fibrosis (IPF) is one of the most aggressive forms of idiopathic interstitial pneumonias, characterized by chronic and progressive fibrosis subverting the lung's architecture, pulmonary functional decline, progressive respiratory failure, and high mortality (median survival 3 years after diagnosis). Among the mechanisms associated with disease onset and progression, it has been hypothesized that IPF lungs might be affected either by a regenerative deficit of the alveolar epithelium or by a dysregulation of repair mechanisms in response to alveolar and vascular damage. This latter might be related to the progressive dysfunction and exhaustion of the resident stem cells together with a process of cellular and tissue senescence. The role of endogenous mesenchymal stromal/stem cells (MSCs) resident in the lung in the homeostasis of these mechanisms is still a matter of debate. Although endogenous MSCs may play a critical role in lung repair, they are also involved in cellular senescence and tissue ageing processes with loss of lung regenerative potential. In addition, MSCs have immunomodulatory properties and can secrete anti-fibrotic factors. Thus, MSCs obtained from other sources administered systemically or directly into the lung have been investigated for lung epithelial repair and have been explored as a potential therapy for the treatment of lung diseases including IPF. Given these multiple potential roles of MSCs, this review aims both at elucidating the role of resident lung MSCs in IPF pathogenesis and the role of administered MSCs from other sources for potential IPF therapies.

Air Pollution-An Overlooked Risk Factor for Idiopathic Pulmonary Fibrosis

Air pollution is a major environmental risk to health and a global public health concern. In 2016, according to the World Health Organization (WHO), ambient air pollution in cities and rural areas was estimated to cause 4.2 million premature deaths. It is estimated that around 91% of the world’s population lives in places where air pollution exceeds the limits recommended by the WHO. Sources of air pollution are multiple and context-specific. Air pollution exposures are established risk factors for development and adverse health outcomes in many respiratory diseases, including asthma, chronic obstructive pulmonary disease (COPD), or lung cancer. However, possible associations between air pollution and idiopathic pulmonary fibrosis (IPF) have not been adequately studied and air pollution seems to be an underrecognized risk factor for IPF. This narrative review describes potential mechanisms triggered by ambient air pollution and their possible roles in the initiation of the pathogenic process and adverse health effects in IPF. Additionally, we summarize the most current research evidence from the clinical studies supporting links between air pollution and IPF.