The use of cultured human alveolar basal cells to mimic honeycomb formation in idiopathic pulmonary fibrosis

BACKGROUND

Honeycomb cysts (HC) within the alveolar region are distinct histopathological features in the lungs of idiopathic pulmonary fibrosis (IPF) patients. HC are lined with a single-or stratified layer of basal cells (BC), or with a bronchiolar-like epithelium composed of basal-, ciliated- and secretory epithelial cells. By using cultured IPF patient-derived alveolar BC, we aimed to establish an in vitro- and in vivo model to mimic HC formation in IPF. We (1) optimized conditions to culture and propagate IPF patient-derived alveolar BC, (2) cultured the cells on an air liquid interface (ALI) or in a three dimensional (3D) organoid model, and (3) investigated the cells` behavior after instillation into bleomycin-challenged mice.

METHODS

Alveolar BC were cultured from peripheral IPF lung tissue and grown on tissue-culture treated plastic, an ALI, or in a 3D organoid model. Furthermore, cells were instilled into bleomycin-challenged NRG mice. Samples were analyzed by TaqMan RT-PCR, immunoblotting, immunocytochemistry/immunofluorescence (ICC/IF), or immunohistochemistry (IHC)/IF. Mann-Whitney tests were performed using GraphPad Prism software.

RESULTS

Cultured alveolar BC showed high expression of canonical basal cell markers (TP63, keratin (KRT)5, KRT14, KRT17), robust proliferation, and wound closure capacity. The cells could be cryopreserved and propagated for up to four passages without a significant loss of basal cell markers. When cultured on an ALI or in a 3D organoid model, alveolar BC differentiated to ciliated- and secretory epithelial cells. When instilled into bleomycin-challenged mice, human alveolar BC cells formed HC-like structures composed of human basal-, and secretory epithelial cells within the mouse parenchyma.

CONCLUSION

IPF patient-derived alveolar BC on an ALI, in 3D organoids or after instillation into bleomycin-challenged mice form HC-like structures that closely resemble HC within the IPF lung. These models therefore represent powerful tools to study honeycomb formation, and its potential therapeutic inhibition in IPF.

Anti-Fibrotic Effect of SDF-1β Overexpression in Bleomycin-Injured Rat Lung

Rational: Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease and is associated with high mortality due to a lack of effective treatment. Excessive deposition of the extracellular matrix by activated myofibroblasts in the alveolar space leads to scar formation that hinders gas exchange. Therefore, selectively removing activated myofibroblasts with the aim to repair and remodel fibrotic lungs is a promising approach. Stromal-derived growth factor (SDF-1) is known to stimulate cellular signals which attract stem cells to the site of injury for tissue repair and remodeling. Here, we investigate the effect of overexpression of SDF-1β on lung structure using the bleomycin-injured rat lung model. Methods: Intratracheal administration of bleomycin was performed in adult male rats (F344). Seven days later, in vivo electroporation-mediated gene transfer of either SDF-1β or the empty vector was performed. Animals were sacrificed seven days after gene transfer and histology, design-based stereology, flow cytometry, and collagen measurement were performed on the tissue collected. For in vitro experiments, lung fibroblasts obtained from IPF patients were used. Results: Seven days after SDF-1β gene transfer to bleomycin-injured rat lungs, reduced total collagen, reduced collagen fibrils, improved histology and induced apoptosis of myofibroblasts were observed. Furthermore, it was revealed that TNF-α mediates SDF-1β-induced apoptosis of myofibroblasts; moreover, SDF-1β overexpression increased alveolar epithelial cell numbers and proliferation in vivo and also induced their migration in vitro. Conclusions: Our study demonstrates a new antifibrotic mechanism of SDF-1β overexpression and suggests SDF-1β as a potential new approach for the treatment of lung fibrosis.

Basal-Like Cell-Conditioned Medium Exerts Anti-Fibrotic Effects In Vitro and In Vivo

In idiopathic pulmonary fibrosis (IPF), basal-like cells are atypically present in the alveolar region, where they may affect adjacent stromal cells by paracrine mechanisms. We here aimed to confirm the presence of basal-like cells in peripheral IPF lung tissue in vivo, to culture and characterize the cells in vitro, and to investigate their paracrine effects on IPF fibroblasts in vitro and in bleomycin-injured rats in vivo. Basal-like cells are mainly localized in areas of pathological bronchiolization or honeycomb cysts in peripheral IPF lung tissue. Single-cell RNA sequencing (scRNA-seq) demonstrated an overall homogeneity, the expression of the basal cell markers cytokeratin KRT5 and KRT17, and close transcriptomic similarities to basal cells in the majority of cells cultured in vitro. Basal-like cells secreted significant levels of prostaglandin E2 (PGE2), and their conditioned medium (CM) inhibited alpha-smooth muscle actin (α-SMA) and collagen 1A1 (Col1A1) and upregulated matrix metalloproteinase-1 (MMP-1) and hepatocyte growth factor (HGF) by IPF fibroblasts in vitro. The instillation of CM in bleomycin-injured rat lungs resulted in reduced collagen content, improved lung architecture, and reduced α-SMA-positive cells. Our data suggested that basal-like cells may limit aberrant fibroblast activation and differentiation in IPF through paracrine mechanisms.

Is sleep-disordered breathing a risk factor for COVID-19 or vice versa?

Sleep is a physiologically invigorating, mostly nocturnal state, that plays an important role in the empowerment of the immune system [1]. Obstructive sleep apnoea (OSA) is the most frequent form of sleep disordered breathing (SDB) [2], which may represent a relevant risk factor for the clinical course and prognosis of coronavirus disease 2019 (COVID-19) [3, 4]. Common characteristics and comorbidities of OSA and COVID-19 (male gender, age >60 years, metabolic syndrome, cardiovascular and chronic pulmonary disease) were recently described as prognostic factors in COVID-19 [5]. However, the prevalence of SDB after COVID-19 remains insufficiently explored.

Sleep disordered breathing may be a risk factor or a sequela of COVID-19.https://bit.ly/37v5Gyz

Case Report: Opposite Effects of BRAF Inhibition on Closely Related Clonal Myeloid Disorders

Langerhans cell histiocytosis (LCH) commonly co-occurs with additional myeloid malignancies. The introduction of targeted therapies, blocking “driver” mutations (e.g., BRAF V600E), enabled long-term remission in patients with LCH. The effect of BRAF inhibition on the course and the prognosis of co-existing clonal hematopoiesis is poorly understood. We report on a 61-year-old patient with systemic BRAF V600E positive LCH and concomitant BRAF wild-type (wt) clonal cytopenia of unknown significance (CCUS) with unfavorable somatic mutations including loss of function (LOF) of NF1. While manifestations of LCH improved after blocking BRAF by dabrafenib treatment, the BRAF wt CCUS progressed to acute myeloid leukemia (AML). The patient eventually underwent successful allogeneic hematopoietic stem cell transplantation (HSCT). We performed an in-depth analyzes of the clonal relationship of CCUS and the tissue affected by LCH by using next-generation sequencing (NGS). The findings suggest activation of the mitogen-activated protein (MAP) kinase pathway in the CCUS clone due to the presence of the RAS deregulating NF1 mutations and wt BRAF, which is reportedly associated with paradoxical activation of CRAF and hence MEK. Patients with LCH should be carefully screened for potential additional clonal hematological diseases. NGS can help predict outcome of the latter in case of BRAF inhibition. Blocking the MAP kinase pathway further downstream (e.g., by using MEK inhibitors) or allogeneic HSCT may be options for patients at risk.

Exercise capacity-impairment after COVID-19 pneumonia is mainly caused by deconditioning

Not pulmonary factors, but physical deconditioning is the main limiting factor of exercise capacity in patients after severe COVID-19 pneumonitis. This underscores the importance of an early rehabilitative intervention in these patients.https://bit.ly/2XVvr6C

Integration of transbronchial cryobiopsy into multidisciplinary board decision: a single center analysis of one hundred consecutive patients with interstitial lung disease

Background

Transbronchial cryobiopsy in the evaluation of patients with interstitial lung diseases (ILD) is expected to reduce the need for surgical lung biopsy (SLB).

Objective

To evaluate the diagnostic value of cryobiopsy in combination with bronchoalveolar lavage (BAL), radiologic and clinical data in patients with ILD.

Methods

Between 08/15 and 01/20 patients with ILD underwent cryobiopsy if they: did not have (i) an usual interstitial pneumonia (UIP)-pattern on CT, (ii) predominant ground-glass opacities suggesting alveolitis, (iii) findings suggestive of sarcoidosis on CT, or if they had (i) a CT showing UIP-pattern, but had findings suggesting alternative diagnosis than idiopathic pulmonary fibrosis (IPF), or (ii) had previous non-diagnostic conventional transbronchial forceps biopsy. Histological findings were integrated into the multidisciplinary team discussion (MDTD) and a diagnostic consensus was sought.

Results

One hundred patients underwent cryobiopsy. In 88/100 patients, cryobiopsy was representative with diagnostic findings in 45/88 and non-specific histological findings in 43/88 patients. In 25/43 with non-specific findings, a consensus diagnosis was reached after MDTD integrating BAL, radiologic and clinical data; eight of the remaining 18 patients with non-specific findings were referred to SLB. In 12/100 patients cryobiopsy was not representative and three of these patients were also referred to SLB. In 7/11 patients (64%) SLB was diagnostic. Complications of cryobiopsy included pneumothorax (14%) and locally controlled bleeding (24%).

Conclusions

The diagnostic yield of cryobiopsy was 70%:45% of cryobiopsies were diagnostic based on histology alone and an additional 25% provided non-specific, but valuable findings allowing a consensus diagnosis after MDTD. Our data demonstrate that the diagnostic value of cryobiopsy is high if combined with BAL, radiologic and clinical data.

Transcriptomic profiling reveals disease-specific characteristics of epithelial cells in idiopathic pulmonary fibrosis

Background

Idiopathic pulmonary fibrosis (IPF) is an incurable disease characterized by progressive lung fibrosis ultimately resulting in respiratory failure and death. Recurrent micro-injuries to the alveolar epithelium and aberrant alveolar wound healing with impaired re-epithelialization define the initial steps of the pathogenic trajectory. Failure of timely alveolar epithelial repair triggers hyper-proliferation of mesenchymal cells accompanied by increased deposition of extracellular matrix into the lung interstitium.

Methods

We previously isolated fibrosis-specific mesenchymal stem cell (MSC)-like cells from lung tissue of patients with interstitial lung diseases. These cells produced factors bearing anti-fibrotic potential and changed their morphology from mesenchymal to epithelial upon culture in an epithelial cell (EC)-specific growth medium. Here, we set out to molecularly characterize these MSC-like cell-derived ECs using global gene expression profiling by RNA-sequencing. Moreover, we aimed at characterizing disease-specific differences by comparing the transcriptomes of ECs from IPF and non-IPF sources.

Results

Our results suggest that differentially expressed genes are enriched for factors related to fibrosis, hypoxia, bacterial colonization and metabolism, thus reflecting many of the hallmark characteristics of pulmonary fibrosis. IPF-ECs showed enrichment of both pro- and anti-fibrotic genes, consistent with the notion of adaptive, compensatory regulation.

Conclusions

Our findings support the hypothesis of a functional impairment of IPF-ECs, which could possibly explain the poor clinical outcome of IPF that roughly compares to those of advanced-stage cancers. Our study provides a valuable resource for downstream mechanistic investigation and the quest for novel therapeutic IPF targets.

Generation of an alveolar epithelial type II cell line from induced pluripotent stem cells

Differentiation of primary alveolar type II epithelial cells (AEC II) to AEC type I in culture is a major barrier in the study of the alveolar epithelium in vitro. The establishment of an AEC II cell line derived from induced pluripotent stem cells (iPSC) represents a novel opportunity to study alveolar epithelial cell biology, for instance, in the context of lung injury, fibrosis, and repair. In the present study, we generated long-lasting AEC II from iPSC (LL-iPSC-AEC II). LL-iPSC-AEC II displayed morphological characteristics of AEC II, including growth in a cobblestone monolayer, the presence of lamellar bodies, and microvilli, as shown by electron microscopy. Also, LL-iPSC-AEC II expressed AEC type II proteins, such as cytokeratin, surfactant protein C, and LysoTracker DND 26 (a marker for lamellar bodies). Furthermore, the LL-iPSC-AEC II exhibited functional properties of AEC II by an increase of transepithelial electrical resistance over time, secretion of inflammatory mediators in biologically relevant quantities (IL-6 and IL-8), and efficient in vitro alveolar epithelial wound repair. Consistent with the AEC II phenotype, the cell line showed the ability to uptake and release surfactant protein B, to secrete phospholipids, and to differentiate into AEC type I. In summary, we established a long-lasting, but finite AEC type II cell line derived from iPSC as a novel cellular model to study alveolar epithelial cell biology in lung health and disease.

Constitutive high expression of protein arginine methyltransferase 1 in asthmatic airway smooth muscle cells is caused by reduced microRNA-19a expression and leads to enhanced remodeling

BACKGROUND

In asthma remodeling airway smooth muscle cells (ASMCs) contribute to airway wall thickness through increased proliferation, migration, and extracellular matrix deposition. Previously, we described that protein arginine methyltransferase 1 (PRMT1) participates in airway remodeling in pulmonary inflammation in E3 rats.

OBJECTIVE

We sought to define the asthma-specific regulatory mechanism of PRMT1 in human ASMCs.

METHODS

ASMCs from healthy subjects and asthmatic patients were activated with platelet-derived growth factor (PDGF)-BB. PRMT1 was localized by means of immunohistochemistry in human lung tissue sections and by means of immunofluorescence in isolated ASMCs. PRMT1 activity was suppressed by the pan-PRMT inhibitor AMI-1, signal transducer and activator of transcription 1 (STAT1) was suppressed by small interfering RNA, and extracellular signal-regulated kinase (ERK) 1/2 mitogen-activated protein kinase (MAPK) was suppressed by PD98059. MicroRNAs (miRs) were assessed by using real-time quantitative PCR and regulated by miR mimics or inhibitors.

RESULTS

PRMT1 expression was significantly increased in lung tissue sections and in isolated ASMCs of patients with severe asthma. PDGF-BB significantly increased PRMT1 expression through ERK1/2 MAPK and STAT1 signaling in control ASMCs, whereas in ASMCs from asthmatic patients, these proteins were constitutively expressed. ASMCs from asthmatic patients had reduced miR-19a expression, causing upregulation of ERK1/2 MAPK, STAT1, and PRMT1. Inhibition of PRMT1 abrogated collagen type I and fibronectin deposition, cell proliferation, and migration of ASMCs from asthmatic patients.

CONCLUSIONS

PRMT1 is a central regulator of tissue remodeling in ASMCs from asthmatic patients through the pathway: PDGF-BB-miR-19a-ERK1/2 MAPK and STAT1. Low miR-19a expression in ASMCs from asthmatic patients is the key event that results in constitutive increased PRMT1 expression and remodeling. Therefore PRMT1 is an attractive target to limit airway wall remodeling in asthmatic patients.

Osteolysis of unknown origin: a case report

Background

Sarcoidosis is a granulomatous disease that may affect any organ of the body. The most frequent loci of manifestation are the lungs. However, there are individual cases where bones are affected. The literature describes cases in which swelling or fistula were the first findings of a bone lesion. This is the first case reporting an osteolysis in both angles of the mandibles which led to the diagnosis of sarcoidosis with multi-organ involvement.

Case presentation

The authors present a 74 years old European female patient without previous diagnosis of sarcoidosis who presented with pain in the area of the jaw angles. There were no further clinical symptoms. Bone biopsy following radiological investigation demonstrated non-caseating granulomas consistent with sarcoidosis of the bone. Further evaluation confirmed multi-organ disease with involvement of lungs, intrathoracic lymph nodes, and the central nervous system.

Conclusion

This case report shows that diagnosis of a severe disease can be missed if systematic clinical signs are not given. Furthermore, an accurate anamnesis and examination is required to receive an early diagnosis which often needs an interdisciplinary approach.

Mode of action of nintedanib in the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and ultimately fatal disease characterised by fibrosis of the lung parenchyma and loss of lung function. Although the pathogenic pathways involved in IPF have not been fully elucidated, IPF is believed to be caused by repetitive alveolar epithelial cell injury and dysregulated repair, in which there is uncontrolled proliferation of lung fibroblasts and differentiation of fibroblasts into myofibroblasts, which excessively deposit extracellular matrix (ECM) proteins in the interstitial space. A number of profibrotic mediators including platelet-derived growth factor (PDGF), fibroblast growth factor (FGF) and transforming growth factor-β are believed to play important roles in the pathogenesis of IPF. Nintedanib is a potent small molecule inhibitor of the receptor tyrosine kinases PDGF receptor, FGF receptor and vascular endothelial growth factor receptor. Data from in vitro studies have shown that nintedanib interferes with processes active in fibrosis such as fibroblast proliferation, migration and differentiation, and the secretion of ECM. In addition, nintedanib has shown consistent anti-fibrotic and anti-inflammatory activity in animal models of lung fibrosis. These data provide a strong rationale for the clinical efficacy of nintedanib in patients with IPF, which has recently been demonstrated in phase III clinical trials.

Nintedanib interferes with processes active in fibrosis, e.g. fibroblast proliferation, migration anddifferentiationhttp://ow.ly/Iae9z

Anti-fibrotic effects of nintedanib in lung fibroblasts derived from patients with idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with poor prognosis. The kinase inhibitor nintedanib specific for vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR) and fibroblast growth factor receptor (FGFR) significantly reduced the rate of decline of forced vital capacity versus placebo.

AIM

To determine the in vitro effect of nintedanib on primary human lung fibroblasts.

METHODS

Fibroblasts were isolated from lungs of IPF patients and from non-fibrotic controls. We assessed the effect of VEGF, PDGF-BB and basic FGF (bFGF) ± nintedanib on: (i) expression/activation of VEGFR, PDGFR, and FGFR, (ii) cell proliferation, secretion of (iii) matrix metalloproteinases (MMP), (iv) tissue inhibitor of metalloproteinase (TIMP), and (v) collagen.

RESULTS

IPF fibroblasts expressed higher levels of PDGFR and FGFR than controls. PDGF-BB, bFGF, and VEGF caused a pro-proliferative effect which was prevented by nintedanib. Nintedanib enhanced the expression of pro-MMP-2, and inhibited the expression of TIMP-2. Transforming growth factor-beta-induced secretion of collagens was inhibited by nintedanib.

CONCLUSION

Our data demonstrate a significant anti-fibrotic effect of nintedanib in IPF fibroblasts. This effect consists of the drug's anti-proliferative capacity, and on its effect on the extracellular matrix, the degradation of which seems to be enhanced.

Calcineurin inhibitors in bronchiolitis obliterans syndrome following stem cell transplantation

Bronchiolitis obliterans is a complication after allogeneic haematopoietic stem cell transplantation (HSCT). Management of bronchiolitis obliterans comprises intensive immunosuppression, but treatment response is poor. We investigated the effect of cyclosporine A (CsA), tacrolimus (FK506), methylprednisolone (mPRED), mycophenolate mofetil (MMF) and everolimus on the proliferation of primary lung myofibroblasts from HSCT patients with bronchiolitis obliterans syndrome (BOS). Cells were isolated from surgical lung biopsies of eight HSCT patients with BOS. Proliferation was assessed by [(3)H]-thymidine incorporation. Biopsies revealed constrictive bronchiolitis obliterans in three patients and lymphocytic bronchiolitis in five patients. CsA and FK506 significantly induced proliferation of myofibroblasts. mPRED and MMF caused a significant inhibition of proliferation, whereas everolimus had no effect. Costimulation with FK506, mPRED and MMF significantly inhibited proliferation. Serial pulmonary function tests over 12 months after lung biopsy and under triple therapy demonstrated that patients with lymphocytic bronchiolitis had a significant improvement in forced expiratory volume in 1 s (FEV1), whereas FEV1 of patients with bronchiolitis obliterans was unchanged. Our data demonstrate a pro-proliferative effect of calcineurin inhibitors on primary human lung myofibroblasts obtained from patients with BOS after HSCT. In contrast, based on the observed antiproliferative capacity of MMF in vitro, MMF-based calcineurin inhibitor-free treatment strategies should be further evaluated in patients with bronchiolitis obliterans after HSCT.

Dimethylfumarate inhibits CXCL10 via haem oxygenase-1 in airway smooth muscle

CXCL10 stimulates mast cell infiltration into airway smooth muscle bundles and, thus, activate cytokine secretion and airway smooth muscle cell (ASMC) proliferation. Dimethylfumarate (DMF) reduces cytokine secretion by lymphocytes and ASMC proliferation through haem oxygenase (HO)-1. Therefore, we investigated the potency of DMF to inhibit tumour necrosis factor (TNF)-α- and interferon (IFN)-γ-induced CXCL10 secretion by human ASMCs. Human primary ASMCs were pre-incubated with DMF and/or fluticasone and/or glutathione ethylester before cells were stimulated with IFN-γ and/or TNF-α. DMF inhibited CXCL10 secretion and increased HO-1 levels, and p38 mitogen-activated protein kinase (MAPK) inhibition reduced DMF-dependent HO-1 expression. The DMF effect on CXCL10 secretion was abrogated by pre-treatment with HO-1 small interfering RNA (siRNA). Glutathione supplementation reversed all DMF effects on CXCL10 secretion and p38 MAPK phosphorylation. Importantly, combining DMF with fluticasone further reduced CXCL10 secretion. In addition, DMF inhibited IFN-γ-induced CXCL10 secretion. This effect was compensated by glutathione supplementation or by pre-treatment with HO-1 siRNA. In addition, DMF reduced TNF-α-induced granulocyte colony-stimulating factor (G-CSF) secretion but had no effect on INF-γ-induced G-CSF secretion. In human primary ASMCs, DMF inhibits CXCL10 secretion by reducing the cellular glutathione level and by activation of p38 MAPK and HO-1. Therefore, DMF may reduce airway inflammation in asthma by a glucocorticoid-independent pathway.

CYCLOSPORINE A MEDIATES FIBROPROLIFERATION THROUGH EPITHELIAL CELLS

BACKGROUND

Obliterative bronchiolitis (OB) is the major cause of morbidity and mortality after lung transplantation. The potential role of immunosuppressive drugs in the development of OB is uncertain, but there are limited data indicating that cyclosporine A (CsA) may have a direct fibrogenic effect on various human cell types. Epithelium-fibroblast interactions have been suggested to play a crucial role in the course of fibroproliferation, which is a major feature of OB.

METHODS

We studied the effect of CsA and FK506 on primary human lung fibroblast proliferation in a human epithelial-fibroblast interactive model.

RESULTS

Clinically relevant concentrations of CsA (0.1-1 microg/mL) and FK506 (0.001-0.01 microg/mL) did not affect fibroblast proliferation in monocultures. Conditioned medium (CM) from untreated epithelial cells (Calu-3) stimulated fibroblast proliferation. CM from FK506-treated (0.001-0.1 microg/mL) epithelial cells had no significant additive effect on fibroblast proliferation compared with CM of untreated epithelial cells. In contrast, CM obtained from epithelial cells treated with 0.1 microg/mL CsA significantly enhanced fibroblast proliferation compared with CM of untreated epithelial cells. This proliferative effect of 0.1 microg/mL CsA was mediated by epithelial-derived factors greater than 100 kDa.

CONCLUSIONS

These data demonstrate that a clinically relevant concentration of CsA stimulates fibroblast proliferation through mediators produced by airway epithelial cells, raising the possibility that CsA may contribute to the development of OB after lung transplantation.