Transpl Int. 2022 May 16;35:10159. doi: 10.3389/ti.2022.10159. eCollection 2022.

ABSTRACT

The MUC5B promoter polymorphism (rs35705950) has been associated with interstitial lung disease (ILD) and with prolonged pre-transplant survival in idiopathic pulmonary fibrosis (IPF), but no information is available regarding its prevalence in other respiratory diseases and its influence on post-transplant outcome. We included the Leuven lung transplantation cohort between 1991 and 2015 (n = 801). We assessed the minor allele frequency (MAF) of the MUC5B variant in the entire study cohort and investigated the influence of recipient MUC5B promoter polymorphism on post-transplant outcome in patients who were transplanted after 2004. MUC5B was successfully genotyped in 746 patients. The MAF was significantly higher in ILD (17.6%) compared to chronic obstructive pulmonary disease (COPD)/emphysema (9.3%), cystic fibrosis (CF)/bronchiectasis (BRECT) (7.5%) and pulmonary hypertension (PHT) (7.4%) (p < 0.001). No association was observed between rs35705950 and chronic lung allograft dysfunction (CLAD)/graft loss in the ILD population [CLAD: HR 1.37 95% CI (0.70-2.68); graft loss: HR 1.02 95% CI (0.55-1.89)], nor the entire study cohort [CLAD: HR 0.96 95% CI (0.69-1.34); graft loss: HR 0.97 95% CI (0.70-1.35)]. The MUC5B promoter polymorphism is a very specific predictive factor for the presence of pulmonary fibrosis as it is only associated with pulmonary fibrosis and not with other chronic respiratory diseases. While the MUC5B promoter variant is associated with better pre-transplant survival among IPF patients, recipient MUC5B promoter variant does not play a role in post-transplant outcome.

PMID:35651878 | PMC:PMC9149783 | DOI:10.3389/ti.2022.10159

Ann Am Thorac Soc. 2022 Jun;19(6):899-901. doi: 10.1513/AnnalsATS.202202-123ED.

NO ABSTRACT

PMID:35648085 | DOI:10.1513/AnnalsATS.202202-123ED

Ann Am Thorac Soc. 2022 Jun;19(6):895-897. doi: 10.1513/AnnalsATS.202112-1353ED.

NO ABSTRACT

PMID:35648084 | DOI:10.1513/AnnalsATS.202112-1353ED

Ann Am Thorac Soc. 2022 Jun;19(6):904-906. doi: 10.1513/AnnalsATS.202204-323ED.

NO ABSTRACT

PMID:35648081 | DOI:10.1513/AnnalsATS.202204-323ED

Tomography. 2022 Apr 20;8(3):1184-1195. doi: 10.3390/tomography8030097.

ABSTRACT

Prior studies variably reported residual chest CT abnormalities after COVID-19. This study evaluates the CT patterns of residual abnormalities in severe COVID-19 pneumonia survivors. All consecutive COVID-19 survivors who received a CT scan 5-7 months after severe pneumonia in two Italian hospitals (Reggio Emilia and Parma) were enrolled. Individual CT findings were retrospectively collected and follow-up CT scans were categorized as: resolution, residual non-fibrotic abnormalities, or residual fibrotic abnormalities according to CT patterns classified following standard definitions and international guidelines. In 225/405 (55.6%) patients, follow-up CT scans were normal or barely normal, whereas in 152/405 (37.5%) and 18/405 (4.4%) patients, non-fibrotic and fibrotic abnormalities were respectively found, and 10/405 (2.5%) had post-ventilatory changes (cicatricial emphysema and bronchiectasis in the anterior regions of upper lobes). Among non-fibrotic changes, either barely visible (n = 110/152) or overt (n = 20/152) ground-glass opacities (GGO), resembling non-fibrotic nonspecific interstitial pneumonia (NSIP) with or without organizing pneumonia features, represented the most common findings. The most frequent fibrotic abnormalities were subpleural reticulation (15/18), traction bronchiectasis (16/18) and GGO (14/18), resembling a fibrotic NSIP pattern. When multiple timepoints were available until 12 months (n = 65), residual abnormalities extension decreased over time. NSIP, more frequently without fibrotic features, represents the most common CT appearance of post-severe COVID-19 pneumonia.

PMID:35645383 | PMC:PMC9149852 | DOI:10.3390/tomography8030097

Respir Res. 2022 Jun 1;23(1):142. doi: 10.1186/s12931-022-02062-1.

ABSTRACT

BACKGROUND: The assessment of lung physiology via pulmonary function tests (PFTs) is essential for patients with idiopathic pulmonary fibrosis (IPF). However, PFTs require active participation, which can be challenging for patients with severe respiratory failure, such as during moments of acute exacerbation (AE) of IPF. Recent advances have enabled the re-construction of 3-dimensional computed-tomography (3D-CT) images. This study established a standardisation method and quantitative analysis of lung volume (LV) based on anthropometry using 3D-CT images.

METHODS: This is a retrospective multi-center cohort study. The standardised 3D-CT LV in patients with IPF at diagnosis (n = 140) and during AE (cohort1; n = 61 and cohort2; n = 50) and those of controls (n = 53) were assessed.

RESULTS: The standardised 3D-CT LVs at IPF diagnosis were less than those of control patients, especially in the lower lung lobes. The standardised 3D-CT LVs were correlated with forced vital capacity (FVC) and validated using the modified Gender-Age-Physiology (GAP) index. The standardised 3D-CT LVs at IPF diagnosis were independently associated with prognosis. During AE, PFTs were difficult to perform, 3D-CT analyses revealed reduced lung capacity in both the upper and lower lobes compared to those obtained at diagnosis. Lower standardised 3D-CT LVs during AE were independently associated with worse outcomes in the two independent cohorts. In particular, volume loss in the upper lobe at AE had prognostic values.

CONCLUSIONS: A novel image quantification method for assessing pulmonary physiology using standardised 3D-CT-derived LVs was developed. This method successfully predicts mortality in patients with IPF and AE of IPF, and may be a useful alternative when PFTs cannot be performed.

PMID:35650599 | DOI:10.1186/s12931-022-02062-1

Respir Res. 2022 May 28;23(1):139. doi: 10.1186/s12931-022-02061-2.

ABSTRACT

BACKGROUND: Pirfenidone slows down disease progression in idiopathic pulmonary fibrosis (IPF). Recent studies suggest a treatment effect in progressive pulmonary fibrosis other than IPF. However, the safety and effectiveness of pirfenidone in asbestosis patients remain unclear. In this study, we aimed to investigate the safety, tolerability and efficacy of pirfenidone in asbestosis patients with a progressive phenotype.

METHODS: This was a multicenter prospective study in asbestosis patients with progressive lung function decline. After a 12-week observational period, patients were treated with pirfenidone 801 mg three times a day. Symptoms and adverse events were evaluated weekly and patients completed online patient-reported outcomes measures. At baseline, start of therapy, 12 and 24 weeks, in hospital measurement of lung function and a 6 min walking test were performed. Additionally, patients performed daily home spirometry measurements.

RESULTS: In total, 10 patients were included of whom 6 patients (66.7%) experienced any adverse events during the study period. Most frequently reported adverse events were fatigue, rash, anorexia and cough, which mostly occurred intermittently and were reported as not very bothersome. No significant changes in hospital pulmonary function (forced vital capacity (FVC), diffusion capacity of the lung for carbon monoxide (DLCO), 6 min walking test or patient-reported outcomes measures before and after start of pirfenidone were found. Home spirometry demonstrated a FVC decline in 12 weeks before start of pirfenidone, while FVC did not decline during the 24 week treatment phase, but this difference was not statistically significant.

CONCLUSIONS: Treatment with pirfenidone in asbestosis has an acceptable safety and tolerability profile and home spirometry data suggest this antifibrotic treatment might attenuate FVC decline in progressive asbestosis. Trial registration MEC-2018-1392; EudraCT number: 2018-001781-41.

PMID:35643466 | DOI:10.1186/s12931-022-02061-2

J Clin Invest. 2022 Jun 1;132(11):e160595. doi: 10.1172/JCI160595.

ABSTRACT

Although aging and lung injury are linked to the development of idiopathic pulmonary fibrosis (IPF), the underlying pathognomonic processes predisposing to fibrotic lesions remain largely unknown. A deficiency in the ability of type 2 alveolar epithelial cell (AEC2) progenitors to regenerate and repair the epithelia has been proposed as a critical factor. In this issue of the JCI, Liang et al. identify a deficiency in the zinc transporter SLC39A8 (ZIP8) in AEC2s and in the subsequent activation of the sirtuin SIRT1 that predisposes to decreased AEC2 renewal capacity and enhanced lung fibrosis in both IPF and aging lungs. Interestingly, the authors demonstrate the efficacy of modulating dietary zinc levels, suggesting the need for clinical trials to evaluate the therapeutic potential of dietary supplementation and the development of pharmacological modulation of the Zn/ZIP8/SIRT1 axis for treatment.

PMID:35642632 | DOI:10.1172/JCI160595

Front Immunol. 2022 May 12;13:880887. doi: 10.3389/fimmu.2022.880887. eCollection 2022.

ABSTRACT

Macrophages are paracrine signalers that regulate tissular responses to injury through interactions with parenchymal cells. Connexin hemichannels have recently been shown to mediate efflux of ATP by macrophages, with resulting cytosolic calcium responses in adjacent cells. Here we report that lung macrophages with deletion of connexin 43 (MacΔCx43) had decreased ATP efflux into the extracellular space and induced a decreased cytosolic calcium response in co-cultured fibroblasts compared to WT macrophages. Furthermore, MacΔCx43 mice had decreased lung fibrosis after bleomycin-induced injury. Interrogating single cell data for human and mouse, we found that P2rx4 was the most highly expressed ATP receptor and calcium channel in lung fibroblasts and that its expression was increased in the setting of fibrosis. Fibroblast-specific deletion of P2rx4 in mice decreased lung fibrosis and collagen expression in lung fibroblasts in the bleomycin model. Taken together, these studies reveal a Cx43-dependent profibrotic effect of lung macrophages and support development of fibroblast P2rx4 as a therapeutic target for lung fibrosis.

PMID:35634278 | PMC:PMC9134074 | DOI:10.3389/fimmu.2022.880887

Respir Med Case Rep. 2022 May 24;38:101674. doi: 10.1016/j.rmcr.2022.101674. eCollection 2022.

ABSTRACT

Coronavirus disease-2019 (COVID-19) is a systemic disorder with the lung and the vasculature being the preferred targets. Patients with interstitial lung diseases represent a category at high risk of progression in the case of Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV)-2 infection, and as such deserve special attention. We first describe the combination of acute exacerbation and pulmonary embolism in an elderly ILD patient after booster anti-COVID-19 mRNA vaccination. Vaccines availability had significantly and safety impacted COVID-19 morbidity and mortality worldwide. Immunization against COVID-19 is indisputable but must not be separated from the awareness of potential adverse effects in fragile patients.

PMID:35637916 | PMC:PMC9126827 | DOI:10.1016/j.rmcr.2022.101674

J Control Release. 2022 May 27:S0168-3659(22)00310-8. doi: 10.1016/j.jconrel.2022.05.039. Online ahead of print.

ABSTRACT

Pulmonary fibrosis (PF) is a serious and progressive lung disease which is possibly life-threatening. It causes lung scarring and affects lung functions including epithelial cell injury, massive recruitment of immune cells and abnormal accumulation of extracellular matrix (ECM). There is currently no cure for PF. Treatment for PF is aimed at slowing the course of the disease and relieving symptoms. Pirfenidone (PFD) and nintedanib (NDNB) are currently the only two FDA-approved oral medicines to slow down the progress of idiopathic pulmonary fibrosis, a specific type of PF. Novel drug delivery systems and therapies have been developed to improve the prognosis of the disease, as well as reduce or minimize the toxicities during drug treatment. The drug delivery routes for these therapies are various including oral, intravenous, nasal, inhalant, intratracheal and transdermal; although this is dependent on specific treatment mechanisms. In addition, researchers have also expanded current animal models that could not fully restore the clinicopathology, and developed a series of in vitro models such as organoids to study the pathogenesis and treatment of PF. This review describes recent advances on pathogenesis exploration, classifies and specifies the progress of drug delivery systems by their delivery routes, as well as an overview on the in vitro and in vivo models for PF research.

PMID:35636615 | DOI:10.1016/j.jconrel.2022.05.039

Phytomedicine. 2022 May 21;102:154177. doi: 10.1016/j.phymed.2022.154177. Online ahead of print.

ABSTRACT

BACKGROUND: Jinshui Huanxian formula (JHF), a traditional Chinese medicine (TCM), has been demonstrated to attenuate idiopathic pulmonary fibrosis (IPF). The active compounds and underlying mechanisms of JHF, however, are unclear.

PURPOSE: The purpose of This study was to aimed to identify the active compounds and pharmacological mechanism of JHF by integrating serum pharmacochemistry with a network pharmacology strategy.

METHODS: JHF was orally administered to a rat model with bleomycin (BLM)-induced pulmonary fibrosis (PF). The pharmacodynamic effects and compounds present in the serum were identified. The targets and biological mechanisms of these compounds were revealed using network analysis and validated using in vitro experiments.

RESULTS: JHF could significantly ameliorate BLM-induced PF by preventing extracellular matrix collagen deposition. Twenty-seven compounds that were found to be enriched in the serum samples collected 1 h after oral administration with JHF were identified as the candidate active compounds, and their 423 potential targets were identified as JHF targets. primarily related to the advanced glycation and products-receptor for advanced glycation end products (AGE-RAGE) signaling pathway, phosphatidylinositol 3 kinase (PI3K)-protein kinase B (PKB or AKT) signaling pathway, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance, etc. The 423 targets, 1145 IPF-related genes and their overlapped genes were applied to analyze, respectively. The results showed that these genes were primarily related to the advanced glycation end-products-receptor for advanced glycation end-products (AGE-RAGE) signaling pathway, lipid and atherosclerosis pathology, phosphatidylinositol 3 kinase (PI3K)-protein kinase B (PKB or AKT) signaling pathway, and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance. Furthermore, the affinity between serum JHF compounds and the main proteins in the above important pathways was investigated through molecular docking. As a result, Molecular docking analysis showed that, tangeretin, isosinensetin, and peimine were found to could bind to EGFR and AKT, and their inhibitory effect on EGFR and AKT were validated in fibroblast cell induced by transforming growth factor (TGF)TGF-β. The results indicated that suppression of fibroblast activation by inhibiting the EGFR/PI3K/AKT signaling pathway might be an important mechanism of JHF may to treat PF.

CONCLUSION: JHF may suppress fibroblast activation by inhibiting the EGFR/PI3K/AKT signaling pathway to ameliorate PF. Tangeretin, isosinensetin, and peimine may be the active compounds in JHF involved in the treatment of that have therapeutic effects on IPF.

PMID:35636171 | DOI:10.1016/j.phymed.2022.154177

J Pathol. 2022 May 30. doi: 10.1002/path.5972. Online ahead of print.

ABSTRACT

The 2022 Annual Review Issue of The Journal of Pathology, Recent Advances in Pathology, contains 15 invited reviews on research areas of growing importance in pathology. This year, the articles include those that focus on digital pathology, employing modern imaging techniques and software to enable improved diagnostic and research applications to study human diseases. This subject area includes the ability to identify specific genetic alterations through the morphological changes they induce, as well as integrating digital and computational pathology with 'omics technologies. Other reviews in this issue include an updated evaluation of mutational patterns (mutation signatures) in cancer, the applications of lineage tracing in human tissues, and single cell sequencing technologies to uncover tumour evolution and tumour heterogeneity. The tissue microenvironment is covered in reviews specifically dealing with proteolytic control of epidermal differentiation, cancer associated fibroblasts, field cancerisation, and host factors that determine tumour immunity. All of the reviews contained in this issue are the work of invited experts selected to discuss the considerable recent progress in their respective fields and are freely available online (https://onlinelibrary.wiley.com/journal/10969896). This article is protected by copyright. All rights reserved.

PMID:35635736 | DOI:10.1002/path.5972

Proteomics. 2022 May 28:e2200018. doi: 10.1002/pmic.202200018. Online ahead of print.

ABSTRACT

IPF is a progressive fibrotic lung disease whose pathogenesis remains incompletely understood. We have previously discovered pathologic mesenchymal progenitor cells (MPCs) in the lungs of IPF patients. IPF MPCs display a distinct transcriptome and create sustained interstitial fibrosis in immune deficient mice. However, the precise pathologic alterations responsible for this fibrotic phenotype remain to be uncovered. Quantitative mass spectrometry and interactomics is a powerful tool that can define protein alterations in specific subcellular compartments that can be implemented to understand disease pathogenesis. We employed quantitative mass spectrometry and interactomics to define protein alterations in the nuclear compartment of IPF MPCs compared to control MPCs. We identified increased nuclear levels of PARP1, CDK1, and BACH1. Interactomics implicated PARP1, CDK1, and BACH1 as key hub proteins in the DNA damage/repair, differentiation, and apoptosis signaling pathways respectively. Loss of function and inhibitor studies demonstrated important roles for PARP1 in DNA damage/repair, CDK1 in regulating IPF MPC stemness and self-renewal, and BACH1 in regulating IPF MPC viability. Our quantitative mass spectrometry studies combined with interactomic analysis uncovered key roles for nuclear PARP1, CDK1 and BACH1 in regulating IPF MPC fibrogenicity. This article is protected by copyright. All rights reserved.

PMID:35633524 | DOI:10.1002/pmic.202200018

Nutrients. 2022 May 19;14(10):2115. doi: 10.3390/nu14102115.

ABSTRACT

Lung diseases, such as asthma, chronic obstructive pulmonary diseases (COPD), and cystic fibrosis (CF), are among the leading causes of mortality and morbidity globally. They contribute to substantial economic burdens on society and individuals. Currently, only a few treatments are available to slow the development and progression of these diseases. Thus, there is an urgent unmet need to develop effective therapies to improve quality of life and limit healthcare costs. An increasing body of clinical and experimental evidence suggests that altered zinc and its regulatory protein levels in the systemic circulation and in the lungs are associated with these disease's development and progression. Zinc plays a crucial role in human enzyme activity, making it an essential trace element. As a cofactor in metalloenzymes and metalloproteins, zinc involves a wide range of biological processes, such as gene transcription, translation, phagocytosis, and immunoglobulin and cytokine production in both health and disease. Zinc has gained considerable interest in these lung diseases because of its anti-inflammatory, antioxidant, immune, and metabolic modulatory properties. Here we highlight the role and mechanisms of zinc in the pathogenesis of asthma, COPD, CF, acute respiratory distress syndrome, idiopathic pulmonary fibrosis, and pulmonary hypertension.

PMID:35631256 | DOI:10.3390/nu14102115

Int J Mol Sci. 2022 May 16;23(10):5548. doi: 10.3390/ijms23105548.

ABSTRACT

Galectins are ten family members of carbohydrate-binding proteins with a high affinity for β galactose-containing oligosaccharides. Galectin-1 (Gal-1) is the first protein discovered in the family, expressed in many sites under normal and pathological conditions. In the first part of the review article, we described recent advances in the Gal-1 modulatory role on wound healing, by focusing on the different phases triggered by Gal-1, such as inflammation, proliferation, tissue repair and re-epithelialization. On the contrary, Gal-1 persistent over-expression enhances angiogenesis and extracellular matrix (ECM) production via PI3K/Akt pathway activation and leads to keloid tissue. Therefore, the targeted Gal-1 modulation should be considered a method of choice to treat wound healing and avoid keloid formation. In the second part of the review article, we discuss studies clarifying the role of Gal-1 in the pathogenesis of proliferative diabetic retinopathy, liver, renal, pancreatic and pulmonary fibrosis. This evidence suggests that Gal-1 may become a biomarker for the diagnosis and prognosis of tissue fibrosis and a promising molecular target for the development of new and original therapeutic tools to treat fibrosis in different chronic diseases.

PMID:35628357 | DOI:10.3390/ijms23105548

Int J Mol Sci. 2022 May 13;23(10):5447. doi: 10.3390/ijms23105447.

ABSTRACT

Idiopathic pulmonary fibrosis (IPF) is a severe fibrotic lung disease characterized by irreversible scarring of the lung parenchyma leading to dyspnea, progressive decline in lung function, and respiratory failure. We analyzed lung transcriptomic data from independent IPF cohorts using weighted gene co-expression network analysis (WGCNA) to identify gene modules based on their preservation status in these cohorts. The consensus gene modules were characterized by leveraging existing clinical and molecular data such as lung function, biological processes, pathways, and lung cell types. From a total of 32 consensus gene modules identified, two modules were found to be significantly correlated with the disease, lung function, and preserved in other IPF datasets. The upregulated gene module was enriched for extracellular matrix, collagen metabolic process, and BMP signaling while the downregulated module consisted of genes associated with tube morphogenesis, blood vessel development, and cell migration. Using a combination of connectivity-based and trait-based significance measures, we identified and prioritized 103 "hub" genes (including 25 secretory candidate biomarkers) by their similarity to known IPF genetic markers. Our validation studies demonstrate the dysregulated expression of CRABP2, a retinol-binding protein, in multiple lung cells of IPF, and its correlation with the decline in lung function.

PMID:35628257 | DOI:10.3390/ijms23105447

Int J Mol Sci. 2022 May 10;23(10):5292. doi: 10.3390/ijms23105292.

ABSTRACT

Idiopathic pulmonary fibrosis (IPF) is a devastating and common chronic lung disease that is pathologically characterized by the destruction of lung architecture and the accumulation of extracellular matrix in the lung. Previous studies have shown an association between lung surfactant protein (SP) and the pathogenesis of IPF, as demonstrated by mutations and the altered expression of SP in patients with IPF. However, the role of SP in the development of lung fibrosis is poorly understood. In this study, the role of surfactant protein A (SP-A) was explored in experimental lung fibrosis induced with a low or high dose of bleomycin (BLM) and CRISPR/Cas9-mediated genetic deletion of SP-A. Our results showed that lung SP-A deficiency in mice promoted the development of fibrotic damage and exacerbated inflammatory responses to the BLM challenge. In vitro experiments with murine lung epithelial LA-4 cells demonstrated that in response to transforming growth factor-β1 (TGF-β1), LA-4 cells had a decreased protein expression of SP-A. Furthermore, exogenous SP administration to LA-4 cells inhibited the TGF-β1-induced upregulation of fibrotic markers. Overall, these findings suggest a novel antifibrotic mechanism of SP-A in the development of lung fibrosis, which indicates the therapeutic potential of the lung SP-A in preventing the development of IPF.

PMID:35628104 | DOI:10.3390/ijms23105292

Cells. 2022 May 12;11(10):1626. doi: 10.3390/cells11101626.

ABSTRACT

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease with limited therapeutic options, and there is a huge unmet need for new therapies. A growing body of evidence suggests that the histone deacetylase (HDAC) family of transcriptional corepressors has emerged as crucial mediators of IPF pathogenesis. HDACs deacetylate histones and result in chromatin condensation and epigenetic repression of gene transcription. HDACs also catalyse the deacetylation of many non-histone proteins, including transcription factors, thus also leading to changes in the transcriptome and cellular signalling. Increased HDAC expression is associated with cell proliferation, cell growth and anti-apoptosis and is, thus, a salient feature of many cancers. In IPF, induction and abnormal upregulation of Class I and Class II HDAC enzymes in myofibroblast foci, as well as aberrant bronchiolar epithelium, is an eminent observation, whereas type-II alveolar epithelial cells (AECII) of IPF lungs indicate a significant depletion of many HDACs. We thus suggest that the significant imbalance of HDAC activity in IPF lungs, with a "cancer-like" increase in fibroblastic and bronchial cells versus a lack in AECII, promotes and perpetuates fibrosis. This review focuses on the mechanisms by which Class I and Class II HDACs mediate fibrogenesis and on the mechanisms by which various HDAC inhibitors reverse the deregulated epigenetic responses in IPF, supporting HDAC inhibition as promising IPF therapy.

PMID:35626663 | DOI:10.3390/cells11101626

Cells. 2022 May 10;11(10):1593. doi: 10.3390/cells11101593.

ABSTRACT

Idiopathic lung fibrosis (IPF) is a fatal lung disease characterized by chronic epithelial injury and exhausted repair capacity of the alveolar compartment, associated with the expansion of cells with intermediate alveolar epithelial cell (AT2) characteristics. Using SftpcCreERT2/+: tdTomatoflox/flox mice, we previously identified a lung population of quiescent injury-activated alveolar epithelial progenitors (IAAPs), marked by low expression of the AT2 lineage trace marker tdTomato (Tomlow) and characterized by high levels of Pd-l1 (Cd274) expression. This led us to hypothesize that a population with similar properties exists in the human lung. To that end, we used flow cytometry to characterize the CD274 cell-surface expression in lung epithelial cells isolated from donor and end-stage IPF lungs. The identity and functional behavior of these cells were further characterized by qPCR analysis, in vitro organoid formation, and ex vivo precision-cut lung slices (PCLSs). Our analysis led to the identification of a population of CD274pos cells expressing intermediate levels of SFTPC, which was expanded in IPF lungs. While donor CD274pos cells initiated clone formation, they did not expand significantly in 3D organoids in AT2-supportive conditions. However, an increased number of CD274pos cells was found in cultured PCLS. In conclusion, we demonstrate that, similar to IAAPs in the mouse lung, a population of CD274-expressing cells exists in the normal human lung, and this population is expanded in the IPF lung and in an ex vivo PCLS assay, suggestive of progenitor cell behavior. CD274 function in these cells as a checkpoint inhibitor may be crucial for their progenitor function, suggesting that CD274 inhibition, unless specifically targeted, might further injure the already precarious lung epithelial compartment in IPF.

PMID:35626630 | DOI:10.3390/cells11101593