Serum C-reactive protein is associated with earlier mortality across different interstitial lung diseases

BACKGROUND AND OBJECTIVE

The acute-phase protein C-reactive protein (CRP) is known to be associated with poor outcomes in cancer and cardiovascular disease, but there is limited evidence of its prognostic implications in interstitial lung diseases (ILDs). We therefore set out to test whether baseline serum CRP levels are associated with mortality in four different ILDs.

METHODS

In this retrospective study, clinically measured CRP levels, as well as baseline demographics and lung function measures, were collected for ILD patients first presenting to the Royal Brompton Hospital between January 2010 and December 2019. Cox regression analysis was used to determine the relationship with 5-year mortality.

RESULTS

Patients included in the study were: idiopathic pulmonary fibrosis (IPF) n = 422, fibrotic hypersensitivity pneumonitis (fHP) n = 233, rheumatoid arthritis associated ILD (RA-ILD) n = 111 and Systemic Sclerosis associated ILD (SSc-ILD) n = 86. Patients with a recent history of infection were excluded. Higher CRP levels were associated with shorter 5-year survival in all four disease groups on both univariable analyses, and after adjusting for age, gender, smoking history, immunosuppressive therapy and baseline disease severity (IPF: HR (95% CI): 1.3 (1.1-1.5), p = 0.003, fHP: 1.5 (1.2-1.9), p = 0.001, RA-ILD: 1.4 (1.1-1.84), p = 0.01 and SSc-ILD: 2.7 (1.6-4.5), p < 0.001).

CONCLUSION

Higher CRP levels are independently associated with reduced 5-year survival in IPF, fHP, RA-ILD and SSc-ILD.

Association of musculoskeletal involvement with lung function and mortality in patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive disease associated with high mortality. Low muscle mass, frailty and sarcopenia lead to functional impairment that negatively impact quality of life and survival but are not used in clinical practice. We aimed to determine the association of Fat-free mass index (FFMI) and frailty with lung function, exercise tolerance and survival in patients with IPF. In this study, 70 patients with IPF underwent assessment of body composition, lung function, 6-min walk distance (6MWD) testing, hand grip strength, quality of life (QoL) assessment by St. George's Respiratory questionnaire (SGRQ) and frailty assessment using the SHARE-FI tool. FFMI was calculated using pectoralis muscle cross-sectional area (PM-CSA) on CT chest images and the lowest quartile defined reduced muscle mass. Sarcopenia was defined as low FFMI and handgrip strength. Regression analyses were conducted to determine predictive value of frailty, low FFMI and sarcopenia on clinical outcomes. The Cox proportional hazards model was used to analyze the impact of FFMI and frailty score on survival. The mean age was 70 years with moderate impairment in lung function (mean ppFVC 68.5%, ppDLCO 45.6%). Baseline forced vital capacity (p < 0.001), diffusion capacity of lung for carbon monoxide (p =  < 0.01), 6WMD (p < 0.05) were significantly lower in frail patients compared to non-frail patients. BMI was found to closely correlate with FFMI (r = 0.79, p < 0.001), but not with frailty score (r = - 0.2, p = 0.07). Frailty was a significant predictor of FVC, DLCO, 6MWD, SGRQ scores when adjusted for age and gender. Muscle mass and sarcopenia were significant predictors of FVC, DLCO, but not 6MWD or QoL scores. Multivariate cox-proportional hazards ratio model adjusting for age and gender showed that frailty was significantly associated with increased mortality (HR = 2.6, 95% CI 1.1-6.1). Low FFMI (HR = 1.3, 95% CI 0.6-2.8), and sarcopenia (HR = 2.1, 95% CI 0.8-5.3), though associated with a trend to increased mortality, were not statistically significant. Frailty is associated with lower lung function and higher mortality in patients with IPF. Longitudinal evaluations are necessary to further determine the associations between low FFMI, sarcopenia and frailty with outcomes in IPF.

Health care costs and utilization of progressive fibrosing lung disease by underlying interstitial lung disease type

BACKGROUND

Fibrosing interstitial lung disease (ILD) encompasses more than 200 diverse pulmonary disorders, of which up to 40% become progressive. The 4 underlying ILD types most likely to result in progression are unclassified ILD/idiopathic interstitial pneumonia (IIP), autoimmune ILDs, exposure-related ILD/hypersensitivity pneumonitis, and sarcoidosis.

OBJECTIVE

To compare health care resource utilization (HCRU) and costs among patients with fibrosing ILD that has progressed ("progressive" fibrosing cohort) vs patients whose fibrosis did not meet criteria set for progression ("not yet progressed" cohort).

METHODS

This was a noninterventional study of commercial enrollees and Medicare Advantage with Part D beneficiaries, which used administrative claims data for the period from October 1, 2015, through May 31, 2021. Adult patients (aged ≥18 years) with fibrosing ILD and 12 months of continuous health plan enrollment were included. Patients with idiopathic pulmonary fibrosis, baseline ILD diagnoses, or missing demographic data were excluded. Patients were first classified according to the underlying type of fibrosing ILD. For statistical analyses of outcomes, 2 cohorts were compared within each subtype: progressive fibrosing ILD vs not yet progressed ILD. The final study population included propensity score-matched (PSM) patients (1:1) based on pre-ILD baseline demographic and clinical characteristics. HCRU categories included inpatient hospitalization counts and the number of inpatient days and total costs (in 2021 US dollars), analyzed descriptively and weighted by the per-patient-per-month cost. Lin's regression was used to predict 12-month total cost estimates for comparison by cohort.

RESULTS

The distribution by underlying conditions was as follows: autoimmune ILD (n = 4,156), HP (n = 8,181), sarcoidosis (n = 775), and unclassified ILD/IIP (n = 18,635). After PSM, pre-ILD baseline variables were generally well balanced between the progressive and not yet progressed fibrosing ILD cohorts. For all underlying subtypes of ILD, patients in the progressive cohort had significantly more utilization and higher costs compared with patients in the not yet progressed cohort. Progressive cohorts had significantly higher adjusted rates of inpatient days among patients with at least 1 inpatient stay compared with the not yet progressed cohorts (all P < 0.01). In addition, the progressive cohorts had significantly higher adjusted 12-month total costs, with the differences ranging from $24,493 to $55,072 (all comparisons P < 0.001).

CONCLUSIONS

Irrespective of underlying ILD type, patients with progressive fibrosing ILD had significantly increased HCRU and cost relative to those whose fibrosing ILD had not yet progressed.

Role of lung ornithine aminotransferase in idiopathic pulmonary fibrosis: regulation of mitochondrial ROS generation and TGF-β1 activity

Idiopathic pulmonary fibrosis (IPF) is characterized by aberrant lung remodeling and the excessive accumulation of extracellular matrix (ECM) proteins. In a previous study, we found that the levels of ornithine aminotransferase (OAT), a principal enzyme in the proline metabolism pathway, were increased in the lungs of patients with IPF. However, the precise role played by OAT in the pathogenesis of IPF is not yet clear. The mechanism by which OAT affects fibrogenesis was assessed in vitro using OAT-overexpressing and OAT-knockdown lung fibroblasts. The therapeutic effects of OAT inhibition were assessed in the lungs of bleomycin-treated mice. OAT expression was increased in fibrotic areas, principally in interstitial fibroblasts, of lungs affected by IPF. OAT levels in the bronchoalveolar lavage fluid of IPF patients were inversely correlated with lung function. The survival rate was significantly lower in the group with an OAT level >75.659 ng/mL than in the group with an OAT level ≤75.659 ng/mL (HR, 29.53; p = 0.0008). OAT overexpression and knockdown increased and decreased ECM component production by lung fibroblasts, respectively. OAT knockdown also inhibited transforming growth factor-β1 (TGF)-β1 activity and TGF-β1 pathway signaling. OAT overexpression increased the generation of mitochondrial reactive oxygen species (ROS) by activating proline dehydrogenase. The OAT inhibitor L-canaline significantly attenuated bleomycin-induced lung injury and fibrosis. In conclusion, increased OAT levels in lungs affected by IPF contribute to the progression of fibrosis by promoting excessive mitochondrial ROS production, which in turn activates TGF-β1 signaling. OAT may be a useful target for treating patients with fibrotic lung diseases, including IPF.

Deep Learning-based Fibrosis Extent on Computed Tomography Predicts Outcome of Fibrosing Interstitial Lung Disease Independent of Visually Assessed Computed Tomography Pattern

Rationale: Radiologic pattern has been shown to predict survival in patients with fibrosing interstitial lung disease. The additional prognostic value of fibrosis extent by quantitative computed tomography (CT) is unknown. Objectives: We hypothesized that fibrosis extent provides information beyond visually assessed CT pattern that is useful for outcome prediction. Methods: We performed a retrospective analysis of chest CT, demographics, longitudinal pulmonary function, and transplantation-free survival among participants in the Pulmonary Fibrosis Foundation Patient Registry. CT pattern was classified visually according to the 2018 usual interstitial pneumonia criteria. Extent of fibrosis was objectively quantified using data-driven textural analysis. We used Kaplan-Meier plots and Cox proportional hazards and linear mixed-effects models to evaluate the relationships between CT-derived metrics and outcomes. Results: Visual assessment and quantitative analysis were performed on 979 enrollment CT scans. Linear mixed-effect modeling showed that greater baseline fibrosis extent was significantly associated with the annual rate of decline in forced vital capacity. In multivariable models that included CT pattern and fibrosis extent, quantitative fibrosis extent was strongly associated with transplantation-free survival independent of CT pattern (hazard ratio, 1.04; 95% confidence interval, 1.04-1.05; P < 0.001; C statistic = 0.73). Conclusions: The extent of lung fibrosis by quantitative CT is a strong predictor of physiologic progression and survival, independent of visually assessed CT pattern.

Prognostic factors associated with mortality in acute exacerbations of idiopathic pulmonary fibrosis: A systematic review and meta-analysis

BACKGROUND

Acute exacerbations of idiopathic pulmonary fibrosis (AE-IPF) increases mortality risk, but which factors increase mortality is unknown. We aimed to perform a prognostic review of factors associated with mortality in patients with IPF.

STUDY DESIGN

and methods: We searched MEDLINE, EMBASE, and CINAHL for studies that reported on the association between any prognostic factor and AE-IPF. We assessed risk of bias using the QUIPS tool. We conduced pairwise meta-analyses using REML heterogeneity estimator, and GRADE approach to assess the certainty of the evidence.

RESULTS

We included 35 studies in our analysis. We found that long-term supplemental oxygen at baseline (aHR 2.52 [95 % CI 1.68 to 3.80]; moderate certainty) and a diagnosis of IPF compared to non-IPF ILD (aHR 2.19 [95 % CI 1.22 to 3.92]; moderate certainty) is associated with a higher risk of death in patients with AE-IPF. A diffuse pattern on high resolution computed tomography (HRCT) compared to a non-diffuse pattern (aHR 2.61 [95 % CI 1.32 to 2.90]; moderate certainty) is associated with a higher risk of death in patients with AE-IPF. We found that using corticosteroids prior to hospital admission (aHR 2.19 [95 % CI 1.26 to 3.82]; moderate certainty) and those with increased neutrophils (by % increase) in bronchoalveolar lavage (BAL) during the exacerbation is associated with a higher risk of death (aHR 1.02 [1.01 to 1.04]; moderate certainty).

INTERPRETATION

Our results have implications for healthcare providers in making treatment decisions and prognosticating the clinical trajectory of patients, for researchers to design future interventions to improve patient trajectory, and for guideline developers in making decisions about resource allocation.

A Deep Learning-Based Radiomic Classifier for Usual Interstitial Pneumonia

BACKGROUND

Because chest CT scan has largely supplanted surgical lung biopsy for diagnosing most cases of interstitial lung disease (ILD), tools to standardize CT scan interpretation are urgently needed.

RESEARCH QUESTION

Does a deep learning (DL)-based classifier for usual interstitial pneumonia (UIP) derived using CT scan features accurately discriminate radiologist-determined visual UIP?

STUDY DESIGN AND METHODS

A retrospective cohort study was performed. Chest CT scans acquired in individuals with and without ILD were drawn from a variety of public and private data sources. Using radiologist-determined visual UIP as ground truth, a convolutional neural network was used to learn discrete CT scan features of UIP, with outputs used to predict the likelihood of UIP using a linear support vector machine. Test performance characteristics were assessed in an independent performance cohort and multicenter ILD clinical cohort. Transplant-free survival was compared between UIP classification approaches using the Kaplan-Meier estimator and Cox proportional hazards regression.

RESULTS

A total of 2,907 chest CT scans were included in the training (n = 1,934), validation (n = 408), and performance (n = 565) data sets. The prevalence of radiologist-determined visual UIP was 12.4% and 37.1% in the performance and ILD clinical cohorts, respectively. The DL-based UIP classifier predicted visual UIP in the performance cohort with sensitivity and specificity of 93% and 86%, respectively, and in the multicenter ILD clinical cohort with 81% and 77%, respectively. DL-based and visual UIP classification similarly discriminated survival, and outcomes were consistent among cases with positive DL-based UIP classification irrespective of visual classification.

INTERPRETATION

A DL-based classifier for UIP demonstrated good test performance across a wide range of UIP prevalence and similarly discriminated survival when compared with radiologist-determined UIP. This automated tool could efficiently screen for UIP in patients undergoing chest CT scan and identify a high-risk phenotype among those with known ILD.

Associations of combined phenotypic ageing and genetic risk with incidence of chronic respiratory diseases in the UK Biobank: a prospective cohort study

BACKGROUND

Accelerated biological ageing has been associated with an increased risk of several chronic respiratory diseases. However, the associations between phenotypic age, a new biological age indicator based on clinical chemistry biomarkers, and common chronic respiratory diseases have not been evaluated.

METHODS

We analysed data from 308 592 participants at baseline in the UK Biobank. The phenotypic age was calculated from chronological age and nine clinical chemistry biomarkers, including albumin, alkaline phosphatase, creatinine, glucose, C-reactive protein, lymphocyte percent, mean cell volume, red cell distribution width and white blood cell count. Furthermore, phenotypic age acceleration (PhenoAgeAccel) was calculated by regressing phenotypic age on chronological age. The associations of PhenoAgeAccel with incident common chronic respiratory diseases and cross-sectional lung function were investigated. Moreover, we constructed polygenic risk scores and evaluated whether PhenoAgeAccel modified the effect of genetic susceptibility on chronic respiratory diseases and lung function.

RESULTS

The results showed significant associations of PhenoAgeAccel with increased risk of idiopathic pulmonary fibrosis (IPF) (hazard ratio (HR) 1.52, 95% CI 1.45-1.59), COPD (HR 1.54, 95% CI 1.51-1.57) and asthma (HR 1.18, 95% CI 1.15-1.20) per 5-year increase and decreased lung function. There was an additive interaction between PhenoAgeAccel and the genetic risk for IPF and COPD. Participants with high genetic risk and who were biologically older had the highest risk of incident IPF (HR 5.24, 95% CI 3.91-7.02), COPD (HR 2.99, 95% CI 2.66-3.36) and asthma (HR 2.07, 95% CI 1.86-2.31). Mediation analysis indicated that PhenoAgeAccel could mediate 10∼20% of the associations between smoking and chronic respiratory diseases, while ∼10% of the associations between particulate matter with aerodynamic diameter <2.5 µm and the disorders were mediated by PhenoAgeAccel.

CONCLUSION

PhenoAgeAccel was significantly associated with incident risk of common chronic respiratory diseases and decreased lung function and could serve as a novel clinical biomarker.

Association of the lung immune prognostic index with the survival of patients with idiopathic interstitial pneumonias

BACKGROUND AND OBJECTIVE

The lung immune prognostic index (LIPI), a simple index calculated from the blood lactate dehydrogenase level and derived neutrophil-to-lymphocyte ratio, is thought to be associated with host immune status. However, the utility of LIPI in patients with idiopathic interstitial pneumonias (IIPs) is unknown.

METHODS

In this multicentre, retrospective, observational study, an association between LIPI and the survival of patients with IIPs was evaluated.

RESULTS

Exploratory and validation cohorts consisting of 460 and 414 patients with IIPs, respectively, were included (159 and 159 patients had idiopathic pulmonary fibrosis [IPF], and 301 and 255 had non-IPF, respectively). In the exploratory cohort, patients with IPF and a low LIPI had significantly better survival than those with a high LIPI (median of 5.6 years vs. 3.9 years, p = 0.016). The predictive ability of LIPI for the survival of patients with IPF was validated in the validation cohort (median of 8.5 years vs. 4.4 years, p = 0.003). In a multivariate Cox proportional hazard analysis, LIPI was selected as an independent predictive factor for the survival of IPF patients. There was no significant association between LIPI and survival of non-IPF patients in the exploratory and validation cohorts.

CONCLUSION

The LIPI was a predictive factor for the survival of patients with IPF and could aid the management of IPF.

A comprehensive comparison of the safety and efficacy of drugs in the treatment of idiopathic pulmonary fibrosis: a network meta-analysis based on randomized controlled trials

OBJECTIVE

Randomized controlled trials(RCTs) of multiple drugs for Idiopathic pulmonary fibrosis(IPF) have been reported and achieved a certain degree of efficacy, however, the difference in safety and efficacy of them for IPF is not yet well understood. The aim of this network meta-analysis is to assess their safety and efficacy in the treatment of IPF and differences in this safety and efficacy comprehensively.

METHODS

The PubMed, EMbase, CENTRAL and MEDLINE were retrieved to find out the RCTs of drugs in the treatment of IPF. The retrieval date is from construction to November 10, 2022. Stata 14.0 and RevMan 5.3 was used for statistical analysis.

REGISTRATION NUMBER

CRD42023385689.

RESULTS

Twenty-four studies with a total of 6208 patients were finally included, including RCTs of 13 drugs. The results of safety showed that there' s no difference in the incidence of SAEs of 13 drugs treated with IPF compared to placebo (P>0.05), and it's also found that Warfarin had a higher all-cause mortality for IPF than placebo (OR = 5.63, 95% CI [1.54 to 20.55]). SUCRA' s scatterplot showed that Pirfenidone, Nintedanib, Sildenafil and Imatinib were lower than placebo, and Warfarin, Ambrisentan and N-acetylcysteine were higher than placebo. The results of effectiveness showed that Nintedanib (MD = -0.08, 95% CI [-0.12 to -0.04]) improved FVC (L)absolute change from baseline in patients better than placebo, and Nintedanib (OR=1.81, 95% CI [1.23 to 2.66]), Pirfenidone (OR=1.85, 95%CI [1.26 to 2.71]) and Pamrevlumab (OR=4.11, 95% CI [1.25 to 13.58]) improved the proportion of patients with a decline in FVC ≥10% predicted better than placebo. SUCRA' s scatterplot showed that Pamrevlumab, Pirfenidone and Nintedanib were lower than placebo, and Warfarin and Ambrisentan were higher than placebo.

CONCLUSION

Compared with other drugs, Nintedanib and Pirfenidone can significantly slow the decline of lung function in patients with IPF, and the safety is higher. Therefore, they can be further promoted in clinical practice. Warfarin and Ambrisentan shouldn't be used clinically for IPF as the safety and efficacy of them are poor compared to other drugs and placebo. Pamrevlumab may become important drugs for the treatment of IPF in the future.

Expansion of distinct peripheral blood myeloid cell subpopulations in patients with rheumatoid arthritis-associated interstitial lung disease

OBJECTIVES

Interstitial lung disease (ILD) is associated with significant mortality in rheumatoid arthritis (RA) patients with key cellular players remaining largely unknown. This study aimed to characterize inflammatory and myeloid derived suppressor cell (MDSC) subpopulations in RA-ILD as compared to RA, idiopathic pulmonary fibrosis (IPF) without autoimmunity, and controls.

METHODS

Peripheral blood was collected from patients with RA, RA-ILD, IPF, and controls (N = 60, 15/cohort). Myeloid cell subpopulations were identified phenotypically by flow cytometry using the following markers:CD45,CD3,CD19,CD56,CD11b,HLA-DR,CD14,CD16,CD15,CD125,CD33. Functionality of subsets were identified with intracellular arginase-1 (Arg-1) and inducible nitric oxide synthase (iNOS) expression.

RESULTS

There was increased intermediate (CD14++CD16+) and nonclassical (CD14+/-CD16++) and decreased classical (CD14++CD16-) monocytes in RA, RA-ILD, and IPF vs. control. Intermediate monocytes were higher and classical monocytes were lower in RA-ILD vs. RA but not IPF. Monocytic (m)MDSCs were higher in RA-ILD vs. control and RA but not IPF. Granulocytic (g)MDSCs did not significantly differ. In contrast, neutrophils were increased in IPF and RA-ILD patients with elevated expression of Arg-1 sharing similar dimensional clustering pattern. Eosinophils were increased in RA-ILD vs. controls, RA and IPF. Across cohorts, iNOS was decreased in intermediate/nonclassical monocytes but increased in mMDSCs vs. classical monocytes. In RA-ILD, iNOS positive mMDSCs were increased versus classic monocytes.

CONCLUSIONS

Myeloid cell subpopulations are significantly modulated in RA-ILD patients with expansion of CD16+ monocytes, mMDSCs, and neutrophils, a phenotypic profile more aligned with IPF than other RA patients. Eosinophil expansion was unique to RA-ILD, potentially facilitating disease pathogenesis and providing a future therapeutic target.

Inhibitor of PD-1/PD-L1: a new approach may be beneficial for the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a globally prevalent, progressive disease with limited treatment options and poor prognosis. Because of its irreversible disease progression, IPF affects the quality and length of life of patients and imposes a significant burden on their families and social healthcare services. The use of the antifibrotic drugs pirfenidone and nintedanib can slow the progression of the disease to some extent, but it does not have a reverse effect on the prognosis. The option of lung transplantion is also limited owing to contraindications to transplantation, possible complications after transplantation, and the risk of death. Therefore, the discovery of new, effective treatment methods is an urgent need. Over recent years, various studies have been undertaken to investigate the relationship between interstitial pneumonia and lung cancer, suggesting that some immune checkpoints in IPF are similar to those in tumors. Immune checkpoints are a class of immunosuppressive molecules that are essential for maintaining autoimmune tolerance and regulating the duration and magnitude of immune responses in peripheral tissues. They can prevent normal tissues from being damaged and destroyed by the immune response. While current studies have focused on PD-1/PD-L1 and CTLA-4, PD-1/PD-L1 may be the only effective immune checkpoint IPF treatment. This review discusses the application of PD-1/PD-L1 checkpoint in IPF, with the aim of finding a new direction for IPF treatment.

The association between adipokines and pulmonary diseases: a mendelian randomization study

BACKGROUND

The role of adipokines in the development of lung diseases is significant, yet their specific relationship with different lung diseases remains unclear.

METHODS

In our research, we analyzed genetic variations associated with adipokines and various lung conditions such as interstitial lung disease, chronic obstructive pulmonary disease, asthma, lung cancer, sleep apnea, pneumonia, and tuberculosis, using data from public genome-wide studies. We employed Mendelian randomization techniques, including inverse variance weighting, weighted median, and MR-Egger regression methods, and conducted sensitivity checks to validate our findings.

RESULTS

A study using the FinnGen database, which included 198,955 participants, identified 13 SNPs associated with adiponectin. Notably, adiponectin was found to significantly reduce the risk of interstitial lung disease and idiopathic pulmonary fibrosis. However, little evidence was found to establish a direct cause-effect relationship between the six adipokines and several other lung conditions, including sarcoidosis, asthma, chronic obstructive pulmonary disease, lung cancer, tuberculosis, pneumonia, and sleep apnea syndrome.

CONCLUSION

This study reveals a reverse link between adiponectin levels and the likelihood of interstitial lung disease, including idiopathic pulmonary fibrosis.

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.

High-dimensional comparison of monocytes and T cells in post-COVID and idiopathic pulmonary fibrosis

Introduction

Up to 30% of hospitalized COVID-19 patients experience persistent sequelae, including pulmonary fibrosis (PF).

Methods

We examined COVID-19 survivors with impaired lung function and imaging worrisome for developing PF and found within six months, symptoms, restriction and PF improved in some (Early-Resolving COVID-PF), but persisted in others (Late-Resolving COVID-PF). To evaluate immune mechanisms associated with recovery versus persistent PF, we performed single-cell RNA-sequencing and multiplex immunostaining on peripheral blood mononuclear cells from patients with Early- and Late-Resolving COVID-PF and compared them to age-matched controls without respiratory disease.

Results and discussion

Our analysis showed circulating monocytes were significantly reduced in Late-Resolving COVID-PF patients compared to Early-Resolving COVID-PF and non-diseased controls. Monocyte abundance correlated with pulmonary function forced vital capacity and diffusion capacity. Differential expression analysis revealed MHC-II class molecules were upregulated on the CD8 T cells of Late-Resolving COVID-PF patients but downregulated in monocytes. To determine whether these immune signatures resembled other interstitial lung diseases, we analyzed samples from Idiopathic Pulmonary Fibrosis (IPF) patients. IPF patients had a similar marked decrease in monocyte HLA-DR protein expression compared to Late-Resolving COVID-PF patients. Our findings indicate decreased circulating monocytes are associated with decreased lung function and uniquely distinguish Late-Resolving COVID-PF from Early-Resolving COVID-PF, IPF, and non-diseased controls.

In Vivo and In Vitro Pro-Fibrotic Response of Lung-Resident Mesenchymal Stem Cells from Patients with Idiopathic Pulmonary Fibrosis

Lung-resident mesenchymal stem cells (LR-MSC) are thought to participate in idiopathic pulmonary fibrosis (IPF) by differentiating into myofibroblasts. On the other hand, LR-MSC in IPF patients present senescence-related features. It is unclear how they respond to a profibrotic environment. Here, we investigated the profibrotic response of LR-MSC isolated from IPF and control (CON) patients. LR-MSC were inoculated in mice 48 h after bleomycin (BLM) instillation to analyze their contribution to lung damage. In vitro, LR-MSC were exposed to TGFβ. Mice inoculated with IPF LR-MSC exhibited worse maintenance of their body weight. The instillation of either IPF or CON LR-MSC sustained BLM-induced histological lung damage, bronchoalveolar lavage fluid cell count, and the expression of the myofibroblast marker, extracellular matrix (ECM) proteins, and proinflammatory cytokines in the lungs. In vitro, IPF LR-MSC displayed higher basal protein levels of aSMA and fibronectin than CON LR-MSC. However, the TGFβ response in the expression of TGFβ, aSMA, and ECM genes was attenuated in IPF LR-MSC. In conclusion, IPF LR-MSC have acquired myofibroblastic features, but their capacity to further respond to profibrotic stimuli seems to be attenuated. In an advanced stage of the disease, LR-MSC may participate in disease progression owing to their limited ability to repair epithelial damage.

SGK1 aggravates idiopathic pulmonary fibrosis by triggering H3k27ac-mediated macrophage reprogramming and disturbing immune homeostasis

Idiopathic pulmonary fibrosis (IPF) is characterized by fibrotic matrix deposition and irreversible aberrant tissue remodeling. Their mechanisms of action are associated with the activation of macrophages and a disturbed immune environment. We aim to determine how these activated macrophages influenced the pathogenesis of pulmonary fibrosis. We found the fibrotic areas of IPF patients contained more serum and glucocorticoid-induced kinase 1 (SGK1)-positive and M2-type macrophages. Similarly, bleomycin (BLM)+LPS significantly triggered high expression of SGK1 in the IPF mice, accompanied by destroyed lung structure and function, increased fibrosis markers and disturbed immune microenvironment. Mechanistically, SGK1 markedly promoted the reprogramming of M2-type macrophages in fibrotic lungs by triggering glycogen synthase kinase 3beta (GSK3β)-tat-interacting protein 60 (TIP60)- histone-3 lysine-27 acetylation (H3K27ac) signalings, which further released chemokine (C-C motif) ligand 9 (CCL9) to attract Th17 cells and delivered TGF-β to fibroblasts for synergistically destroying immune microenvironment, which was largely reversed by macrophage depletion in mice. We took macrophages as the entry point to deeply analyze IPF pathogenesis and further provided insights for the development of novel drugs represented by SGK1.

Air pollution exposure and its effects on idiopathic pulmonary fibrosis: clinical worsening, lung function decline, and radiological deterioration

Introduction

Major urban pollutants have a considerable influence on the natural history of lung disease. However, this effect is not well known in idiopathic pulmonary fibrosis (IPF).

Aim

This study aimed to investigate the effects of air pollution on clinical worsening, lung function, and radiological deterioration in patients with IPF.

Methods

This exploratory retrospective cohort study included 69 patients with IPF, monitored from 2011 to 2020. Data on air pollution levels, including carbon monoxide (CO), nitrogen dioxide (NO2), particulate matter ≤ 2.5 μM (PM2.5), ozone (O3), and nitrogen oxides (NOx), were collected from the nearest air quality monitoring stations (<3.5 km from the patients' homes). Patient outcomes such as clinical worsening, lung function decline, and radiological deterioration were assessed over various exposure periods (1, 3, 6, 12, and 36 months). The statistical analyses were adjusted for various factors, including age, sex, smoking status, and treatment.

Results

There was an association between higher O3 levels and an increased likelihood of clinical worsening over 6 and 36 months of exposure (odds ratio [OR] and 95% confidence interval [CI] = 1.16 [1.01-1.33] and OR and 95% CI = 1.80 [1.07-3.01], respectively). Increased CO levels were linked to lung function decline over 12-month exposure periods (OR and 95% CI 1.63 = [1.01-2.63]). Lastly, radiological deterioration was significantly associated with higher CO, NO2, and NOx levels over 6-month exposure periods (OR and 95% CI = 2.14 [1.33-3.44], OR and 95% CI = 1.76 [1.15-2.66] and OR and 95% CI = 1.16 [1.03-1.3], respectively).

Conclusion

This study suggests that air pollution, specifically O3, CO, NO2, and NOx, could affect clinical worsening, lung function, and radiological outcomes in patients with IPF. These findings highlight the potential role of air pollution in the progression of IPF, emphasizing the need for further research and air quality control measures to mitigate its effects on respiratory health.

Unraveling the mechanism of ethyl acetate extract from Prismatomeris connata Y. Z. Ruan root in treating pulmonary fibrosis: insights from bioinformatics, network pharmacology, and experimental validation

Introduction

Pulmonary fibrosis is a terminal lung disease characterized by fibroblast proliferation, extracellular matrix accumulation, inflammatory damage, and tissue structure destruction. The pathogenesis of this disease, particularly idiopathic pulmonary fibrosis (IPF), remains unknown. Macrophages play major roles in organ fibrosis diseases, including pulmonary fibrosis. The phenotype and polarization of macrophages are closely associated with pulmonary fibrosis. A new direction in research on anti-pulmonary fibrosis is focused on developing drugs that maintain the stability of the pulmonary microenvironment.

Methods

We obtained gene sequencing data and clinical information for patients with IPF from the GEO datasets GSE110147, GSE15197, GSE24988, GSE31934, GSE32537, GSE35145, GSE53845, GSE49072, GSE70864, and GSE90010. We performed GO, KEGG enrichment analysis and GSEA analysis, and conducted weighted gene co-expression network analysis. In addition, we performed proteomic analysis of mouse lung tissue. To verify the results of bioinformatics analysis and proteomic analysis, mice were induced by intratracheal instillation of bleomycin (BLM), and gavaged for 14 days after modeling. Respiratory function of mice in different groups was measured. Lung tissues were retained for histopathological examination, Western Blot and real-time quantitative PCR, etc. In addition, lipopolysaccharide, interferon-γ and interleukin-4 were used to induce RAW264.7 cells for 12h in vitro to establish macrophage inflammation and polarization model. At the same time, HG2 intervention was given. The phenotype transformation and cytokine secretion of macrophages were investigated by Western Blot, RT-qPCR and flow cytometry, etc.

Results

Through bioinformatics analysis and experiments involving bleomycin-induced pulmonary fibrosis in mice, we confirmed the importance of macrophage polarization in IPF. The analysis revealed that macrophage polarization in IPF involves a change in the phenotypic spectrum. Furthermore, experiments demonstrated high expression of M2-type macrophage-associated biomarkers and inducible nitric oxide synthase, thus indicating an imbalance in M1/M2 polarization of pulmonary macrophages in mice with pulmonary fibrosis.

Discussion

Our investigation revealed that the ethyl acetate extract (HG2) obtained from the roots of Prismatomeris connata Y. Z. Ruan exhibits therapeutic efficacy against bleomycin-induced pulmonary fibrosis. HG2 modulates macrophage polarization, alterations in the TGF-β/Smad pathway, and downstream protein expression in the context of pulmonary fibrosis. On the basis of our findings, we believe that HG2 has potential as a novel traditional Chinese medicine component for treating pulmonary fibrosis.

Hospitalisation patterns in interstitial lung diseases: data from the EXCITING-ILD registry

BACKGROUND

Interstitial lung diseases (ILD) comprise a heterogeneous group of mainly chronic lung diseases with more than 200 entities and relevant differences in disease course and prognosis. Little data is available on hospitalisation patterns in ILD.

METHODS

The EXCITING-ILD (Exploring Clinical and Epidemiological Characteristics of Interstitial Lung Diseases) registry was analysed for hospitalisations. Reasons for hospitalisation were classified as all cause, ILD-related and respiratory hospitalisations, and patients were analysed for frequency of hospitalisations, time to first non-elective hospitalisation, mortality and progression-free survival. Additionally, the risk for hospitalisation according to GAP index and ILD subtype was calculated by Cox proportional-hazard models as well as influencing factors on prediction of hospitalisation by logistic regression with forward selection.

RESULTS

In total, 601 patients were included. 1210 hospitalisations were recorded during the 6 months prior to registry inclusion until the last study visit. 800 (66.1%) were ILD-related, 59.3% of admissions were registered in the first year after inclusion. Mortality was associated with all cause, ILD-related and respiratory-related hospitalisation. Risk factors for hospitalisation were advanced disease (GAP Index stages II and III) and CTD (connective tissue disease)-ILDs. All cause hospitalisations were associated with pulmonary hypertension (OR 2.53, p = 0.005). ILD-related hospitalisations were associated with unclassifiable ILD and concomitant emphysema (OR = 2.133, p = 0.001) as well as with other granulomatous ILDs and a positive smoking status (OR = 3.082, p = 0.005).

CONCLUSION

Our results represent a crucial contribution in understanding predisposing factors for hospitalisation in ILD and its major impact on mortality. Further studies to characterize the most vulnerable patient group as well as approaches to prevent hospitalisations are warranted.

Glycolysis Reprogramming in Idiopathic Pulmonary Fibrosis: Unveiling the Mystery of Lactate in the Lung

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease characterized by excessive deposition of fibrotic connective tissue in the lungs. Emerging evidence suggests that metabolic alterations, particularly glycolysis reprogramming, play a crucial role in the pathogenesis of IPF. Lactate, once considered a metabolic waste product, is now recognized as a signaling molecule involved in various cellular processes. In the context of IPF, lactate has been shown to promote fibroblast activation, myofibroblast differentiation, and extracellular matrix remodeling. Furthermore, lactate can modulate immune responses and contribute to the pro-inflammatory microenvironment observed in IPF. In addition, lactate has been implicated in the crosstalk between different cell types involved in IPF; it can influence cell-cell communication, cytokine production, and the activation of profibrotic signaling pathways. This review aims to summarize the current research progress on the role of glycolytic reprogramming and lactate in IPF and its potential implications to clarify the role of lactate in IPF and to provide a reference and direction for future research. In conclusion, elucidating the intricate interplay between lactate metabolism and fibrotic processes may lead to the development of innovative therapeutic strategies for IPF.

The role of pulmonary rehabilitation in idiopathic pulmonary fibrosis: An overview of systematic reviews

BACKGROUND

The role of pulmonary rehabilitation (PR) in idiopathic pulmonary fibrosis (IPF) has been studied in several systematic reviews (SRs), but no definitive conclusions have been drawn due to the wide variation in the quality and outcomes of the studies. And there are no studies to assess the quality of relevant published SRs. This overview aims to determine the effectiveness of PR in patients with IPF and to summarize and critically evaluate the risk of bias, methodological, and evidence quality of SRs on this related topic.

METHODS

With no language restrictions, eight databases were searched from inception to March 10, 2023. The literature search, screening, and data extraction were carried out separately by two reviewers. We assessed the risk of bias using the ROBIS tool, the reporting quality using PRISMA statements, the methodological quality using AMSTAR-2, and the evidence quality using Grades of Recommendations, Assessment, Development, and Evaluation (GRADE).

RESULTS

Seven SRs from 2018-2023 (including 1836 participants) on PR for the treatment of IPF were selected, all of which included patients with a definitive diagnosis of IPF. After strict evaluation by the ROBIS tool and AMSTAR-2 tool, 42.86% of the SRs had a high risk of bias and 85.71% of the SRs had critically low methodological quality in this overview. PR might be effective for patients with IPF on exercise capacity, quality of life, and pulmonary function-related outcomes, but we did not find high quality evidence to confirm the effectiveness.

CONCLUSION

PR may appear to be an effective and safe treatment for patients with IPF, but the results of this overview should be interpreted dialectically and with caution. Further high-quality, rigorous studies are urgently needed to draw definitive conclusions and provide scientific evidence.

Bronchoalveolar cytokine profile differentiates Pulmonary Langerhans cell histiocytosis patients from other smoking-related interstitial lung diseases

BACKGROUND

Pulmonary Langerhans cell histiocytosis (PLCH) is a rare interstitial lung disease (ILD) associated with smoking, whose definitive diagnosis requires the exclusion of other forms of ILD and a compatible surgical lung biopsy. Bronchoalveolar lavage (BAL) is commonly proposed for the diagnosis of ILD, including PLCH, but the diagnostic value of this technique is limited. Here, we have analyzed the levels of a panel of cytokines and chemokines in BAL from PLCH patients, in order to identify a distinct immune profile to discriminate PLCH from other smoking related-ILD (SR-ILD), and comparing the results with idiopathic pulmonary fibrosis (IPF) as another disease in which smoking is considered a risk factor.

METHODS

BAL samples were collected from thirty-six patients with different ILD, including seven patients with PLCH, sixteen with SR-ILD and thirteen with IPF. Inflammatory profiles were analyzed using the Human Cytokine Membrane Antibody Array. Principal component analysis (PCA) was performed to reduce dimensionality and protein-protein interaction (PPI) network analysis using STRING 11.5 database were conducted. Finally, Random forest (RF) method was used to build a prediction model.

RESULTS

We have found significant differences (p < 0.05) on thirty-two cytokines/chemokines when comparing BAL from PLCH patients with at least one of the other ILD. Four main groups of similarly regulated cytokines were established, identifying distinct sets of markers for each cluster. Exploratory analysis using PCA (principal component analysis) showed clustering and separation of patients, with the two first components capturing 69.69% of the total variance. Levels of TARC/CCL17, leptin, oncostatin M (OSM) and IP-10/CXCL10 were associated with lung function parameters, showing positive correlation with FVC. Finally, random forest (RF) algorithm demonstrates that PLCH patients can be differentiated from the other ILDs based solely on inflammatory profile (accuracy 96.25%).

CONCLUSIONS

Our results show that patients with PLCH exhibit a distinct BAL immune profile to SR-ILD and IPF. PCA analysis and RF model identify a specific immune profile useful for discriminating PLCH.