Alveolar Cells Research Articles

Abstract A015: Aging limits stemness and tumor development in the lung by reprogramming iron homeostasis

Abstract Aging is the most important and well-recognized risk factor for cancer. Aging leads to systemic decline of physical fitness, significantly changing the macroenvironment from the early tumor initiation to the terminal stage of metastasis. However, the underlying mechanisms only start to emerge. Here, using physiologically aged autochthonous genetically engineered mouse models (GEMMs) and primary cells, we demonstrate that aging suppresses lung cancer initiation and progression by degrading stemness of the alveolar cell of origin. Using single-cell transcriptomics, we uncover a distinct compositional landscape of cancer cell subsets in aged lung tumors, revealing a delay in the molecular progression of the lung lesions and an age-specific gene expression signature. Interestingly, key components of this gene signature were traced back to the aged cell of origin. Furthermore, the age-specific signature derived from GEMMs was predictive of patient age in human lung cancer, indicating conservation of the age-associated changes across species. Interestingly, our preliminary data suggested that tumor cells derived from aged tumor-bearing mice displayed higher metastatic potential, indicating that different mechanisms may govern tumor initiation and metastasis. Functional interrogation of the age-specific gene signature revealed that the loss of stemness and tumorigenic capacity is underpinned by aging-associated induction of the transcription factor NUPR1. We find that NUPR1 is induced in the cell of origin in aged mice and humans, which leads to a functional iron insufficiency in the aged cells. Genetic inactivation of the NUPR1 or iron supplementation restores stemness and promotes tumorigenic potential of aged alveolar cells. Conversely, targeting NUPR1 is detrimental to young alveolar cells by promoting ferroptosis. We find that aging-associated DNA hypomethylation at specific enhancer sites results in elevated NUPR1 expression, which is recapitulated in young cells by inhibition of DNA methylation. We uncover that, unlike the young, aged alveolar cells are functionally iron insufficient, which leads to loss of stemness and resistance to ferroptosis. Our results indicate that aging-associated reprogramming of the cell of origin determines tumor initiation potential, alters trajectory of tumor evolution and produces age-dependent vulnerabilities. These findings demonstrate that aging fundamentally changes the biology of lung cancer, shedding light on novel therapeutic modulation of cellular iron homeostasis or ferroptosis in regenerative medicine and in cancer prevention for the elderly population. Citation Format: Xueqian Zhuang, Qing Wang, Simon Joost, Alexander Ferrena, Melissa Blum, Klavdija Krause, Zhuxuan Li, Deyou Zheng, Emily S Wong, Tuomas Tammela. Aging limits stemness and tumor development in the lung by reprogramming iron homeostasis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr A015.

Abstract 4137845: A single-cell lung atlas of human pulmonary arterial hypertension

Introduction: Pulmonary arterial hypertension (PAH) is a disaster disease characterized by obliterative vascular remodeling and persistent increase of vascular resistance, leading to right heart failure and premature death. Understanding the cellular and molecular mechanisms will help develop novel therapeutic approaches for PAH patients. Hypothesis: We hypothesis that single-cell RNA sequencing analysis can help understand the cellular and molecular mechanisms that drive the disease initiation and progression. Methods: 10 healthy donors, 10 idiopathic PAH, 10 drug and toxin induced PAH, 10 systemic and pulmonary shunting induced PAH patients from both male and female, and different ethical groups and races, and ages were obtained from PHBI. Lung tissue specimens were processed for fixed scRNA-seq. The cell proportion change, gene expression, and pathway analysis were evaluated between different disease subclasses, sex, age on different cell types. Results: Our analysis reveals 317,414 cells, 33 clusters and 9 major cell types, including endothelial cells (ECs), alveolar cells, fibroblast, smooth muscle cells (SMCs), pericytes, myeloid cells, lymphocytes, airway epithelial cells, platelet. Cell proportion analysis demonstrated an increase in the proportions of venous ECs, adventitial fibroblasts and myofibroblasts, alveolar macrophages, B cells, plasma cells and a reduction in capillary ECs 2 and pericytes in PAH lungs. KEGG Pathway analysis showed that upregulated pathways related Herpes simplex virus 1 infection, ECM-receptor interaction, Complement and coagulation cascades, Hedgehog signaling, TGF-beta signaling pathway, and downregulated pathways related to IL-17 signaling, TNF signaling, MAPK signaling pathway were enriched in the PAH patients. Female PAH patients exhibit an increase of myofibroblasts and platelets proportion compared to male PAH patients. MsigDB Hallmark Pathway analysis showed that p53 pathway was upregulated, whereas Inflammatory Response, Hypoxia, Epithelial Mesenchymal Transition were downregulated in female PAH patients. PAH patients older than 21 years exhibit an increase in the cell proportion of Platelet, SMCs, Arterial ECs and Venous ECs, and alveolar macrophages and a reduction of B cells and plasma cells. Conclusions: Our integrated analysis of human PAH lung atlas dataset provides a comprehensive understanding of lung cell populations and molecular signature in PAH patients with different sex, age and subclasses

Anti-Inflammatory Effects of SGLT1 Synthetic Ligand in In Vitro and In Vivo Models of Lung Diseases

Background. Several research findings suggest that sodium–glucose co-transporter 1 (SGLT1) is implicated in the progression and control of infections and inflammation processes at the pulmonary level. Moreover, our previous works indicate an engagement of SGLT1 in inhibiting the inflammatory response induced in intestinal epithelial cells by TLR agonists. In this study, we report the anti-inflammatory effects observed in the lung upon engagement of the transporter, and upon the use of glucose and BLF501, a synthetic SGLT1 ligand, for the treatment of animal models of lung inflammation, including a model of allergic asthma. Methods. In vitro experiments were carried out on human pneumocytes stimulated with LPS from Pseudomonas aeruginosa and co-treated with glucose or BLF501, and the production of IL-8 was determined. The anti-inflammatory effect associated with SGLT1 engagement was then assessed in in vivo models of LPS-induced lung injury, as well as in a murine model of ovalbumin (OVA)-induced asthma, treating mice with aerosolized LPS and the synthetic ligand. After the treatments, lung samples were collected and analyzed for morphological alterations by histological examination and immunohistochemical analysis; serum and BALF samples were collected for the determination of several pro- and anti-inflammatory markers. Results. In vitro experiments on human pneumocytes treated with LPS showed significant inhibition of IL-8 production. The results of two in vivo experimental models, mice exposed to aerosolized LPS and OVA-induced asthma, revealed that the engagement of glucose transport protein 1 (SGLT1) induced a significant anti-inflammatory effect in the lungs. In the first model, the acute respiratory distress induced in mice was abrogated by co-treatment with the ligand, with almost complete recovery of the lung morphology and physiology. Similar results were observed in the OVA-induced model of allergic asthma, both with aerosolized and oral BLF501, suggesting an engagement of SGLT1 expressed both in intestinal and alveolar cells. Conclusions. Our results confirmed the engagement of SGLT1 in lung inflammation processes and suggested that BLF501, a non-metabolizable synthetic ligand of the co-transporter, might represent a drug candidate for therapeutic intervention against lung inflammation states.

Design, synthesis and antitumor activity of triphenylphosphonium-linked derivatives of quinazolinone

Cancer is the leading cause of human death. Quinazolinone heterocyclic compounds have a variety of biological activities and have been extensively studied in recent years, especially for their potential anticancer activity. The triphenylphosphonium moiety (TPP+) has become a very important lipophilic cation, especially concerning its application the development of anticancer agents. In this work, we designed and synthesised 24 new TPP+ -conjugated quinazolinone derivatives, which have alkylated TPP+ at the N-3 position and different small group substitutions at the C-6 position, and their antiproliferative activity was evaluated in three cancer cell lines (human alveolar adenocarcinoma cells (A549), human hepatoblastoma cells (HepG2) and human breast cancer cells (MCF-7)) and human normal liver cells (QSG-7701). The cytotoxicity screening results showed that some derivatives exhibited effective inhibitory effects in cancer cells. Among them, the compound 5k–o showed better antiproliferative activity than the positive control drug gefitinib on MCF-7 and A549 cells. The most active compounds being 5o, with IC50 values of 6.56, 14.52 and 7.51 µM in MCF-7 cells, HepG2 cells and A549 cells, respectively. Compound 5o may be a promising compound for cancer treatment worthy of further study.

Prognostic value of alveolar surfactant type-B in acute heart failure: a long-term comparative analysis vs NT-proBNP

Abstract Background In heart failure (HF) biomarkers are an integral component of prognostic assessment. Natriuretic peptides are the gold standard, but they do not directly reflect lung vascular injury. Surfactant type B (Surf-B) is released by type 2 alveolar cells under pressure induced trauma, with few reports just addressing its plasmatic levels in stable chronic HF (CHF). Information on acute HF (AHF) is lacking. Purpose To clarify the prognostic value of Surf-B changes vs NT-proBNP levels after decongestion therapy and to compare their prognostic ability at 1-year follow-up. Methods Patients with acute pulmonary edema (APE) underwent a combined evaluation of Surf-B and NT-proBNP serum levels with quantification of B-lines at hospital admission (time 0), discharge (time 1) and at 1 year (time 2). Results 54 patients (mean age 72.1 ± 11 years; mean LVEF 36% ± 13%; 65% men) were enrolled. At time 1, the average Surf-B, NT-proBNP and B-lines were significantly reduced compared to time 0 (p<0.0001). No correlation between Surf-B and NT-proBNP was observed either at time 0 (r=-0.21; p=0.12) or at time 1 (r=0.05; p=0.71). Despite the significant decrease in Surf-B levels from time 0 to time 1, 18.5% of patients behaved as non-responders exhibiting no changes in Surf-B; conversely, only 5.5% did not show significant reduction in NT-proBNP, despite significant decongestion. 38 patients were followed up to time 2: of these, 13 (34%) reached the composite endpoint of death or hospitalization for HF. Surf-B measured at time 1 was a strong predictor of adverse outcome. Patients with Surf-B above median at discharge displayed a worse survival-free from HF hospitalization compared to the remainders (Log rank p=0.012) (Figure). Also, patients with Surf-B above median at discharge had a more than 4-fold increased risk of the composite endpoint (HR 4.5, 95%CI 1.4-20.2, p=0.023). Conversely, NT-proBNP at discharge was not significantly associated with HF-free survival (Log rank p=0.26) (Figure) and was not a significant predictor of the composite outcome (HR 1.9, 95%CI 0.6-9.3, p=0.25). At ROC analysis, discharge Surf-B levels showed a higher area under the curve (AUC=0.763, p=0.011) than NT-proBNP values (AUC=0.69, p=0.063). Conclusions These data suggest that Surf-B, an organ specific biomarker of lung injury, is highly sensitive to the effectiveness of decongestion therapy, outperforming NT-proBNP. Given the high rate of patients who do not improve their Surf-B levels over time, the reparative processes of alveolar break damage may dissociate from mere decongestion and cardiac healing in AHF.Figure:1yr Kaplan-Meier survival curves

PCLAF-DREAM drives alveolar cell plasticity for lung regeneration

Cell plasticity, changes in cell fate, is crucial for tissue regeneration. In the lung, failure of regeneration leads to diseases, including fibrosis. However, the mechanisms governing alveolar cell plasticity during lung repair remain elusive. We previously showed that PCLAF remodels the DREAM complex, shifting the balance from cell quiescence towards cell proliferation. Here, we find that PCLAF expression is specific to proliferating lung progenitor cells, along with the DREAM target genes transactivated by lung injury. Genetic ablation of Pclaf impairs AT1 cell repopulation from AT2 cells, leading to lung fibrosis. Mechanistically, the PCLAF-DREAM complex transactivates CLIC4, triggering TGF-β signaling activation, which promotes AT1 cell generation from AT2 cells. Furthermore, phenelzine that mimics the PCLAF-DREAM transcriptional signature increases AT2 cell plasticity, preventing lung fibrosis in organoids and mice. Our study reveals the unexpected role of the PCLAF-DREAM axis in promoting alveolar cell plasticity, beyond cell proliferation control, proposing a potential therapeutic avenue for lung fibrosis prevention.

Benzo (A) pyrene exposure alters alveolar epithelial and macrophage cells diversity and induces antioxidant responses in lungs

This study was designed to investigate the toxic effects of benzo (a) pyrene (BaP) in the lungs. Mice were repeatedly treated orally with BaP (50 mg/kg body weight, twice a week for four weeks) to induce a tumour. After 4 months of BaP administration, tumours were visible beneath the skin. The histopathological section of the lungs shows congestion of pulmonary blood vessels, alveolar hyperplasia, and concurrent epithelial hyperplasia with infiltrates of inflammatory cells also seen. Thereafter, a single-cell suspension of lung tissues was stained with fluorescently conjugated antibodies for the demarcation of alveolar epithelial (anti-mouse CD74 and podoplanin) and macrophage (F4/80 and CD11b) cells and measured by flow cytometry. The expression of antioxidant genes was assessed by qRT–PCR. The number of alveolar epithelial cells 1 (AEC1) increased, but the number of alveolar epithelial cells 2 (AEC2) and transitional alveolar epithelial cells (TAEC) was significantly decreased in tumour-bearing mice. The proportion of CD11b+ alveolar macrophages (AM) and interstitial macrophages (IM) was increased, but the proportion of F4/80+ AM cells was reduced. The BaP administration significantly increased the ROS production in alveolar cells. The relative expression levels of antioxidant genes (SOD1, catalase, GPX1, and HIF-1α) were increased, but NRF2 expression was decreased in BaP-treated alveolar cells. The expression of anti-inflammatory (NF-κB) was also significantly increased. In conclusion, BaP exposure induced an inflammatory response, altered alveolar epithelial cell and macrophage diversity, and increased antioxidant responses in the lungs.

Single-cell spatiotemporal analysis reveals alveolar dendritic cell–T cell immunity hubs defending against pulmonary infection

How immune cells are spatiotemporally coordinated in the lung to effectively monitor, respond to, and resolve infection and inflammation in primed form needs to be fully illustrated. Here we apply immunocartography, a high-resolution technique that integrates spatial and single-cell RNA sequencing (scRNA-seq) through deconvolution and co-localization analyses, to the SARS-CoV-2-infected Syrian hamster model. We generate a comprehensive transcriptome map of the whole process of pulmonary infection from physiological condition, infection initiation, severe pneumonia to natural recovery at organ scale and single-cell resolution, with 142,965 cells and 45 lung lobes from 25 hamsters at 5 time points. Integrative analysis identifies that alveolar dendritic cell–T cell immunity hubs, where Ccr7+Ido1+ dendritic cells, Cd160+Cd8+ T cells, and Tnfrsf4+Cd4+ T cells physiologically co-localize, rapidly expand during SARS-CoV-2 infection, eliminate SARS-CoV-2 with the aid of Slamf9+ macrophages, and then restore to physiological levels after viral clearance. We verify the presence of these cell subpopulations in the immunity hubs in normal and SARS-CoV-2-infected hACE2 mouse models, as well as in publicly available human scRNA-seq datasets, demonstrating the potential broad relevance of our findings in lung immunity.

Antiviral Activity of Plant-Based Additives Against African Swine Fever Virus (ASFV) in Feed Ingredients.

African swine fever (ASF) is one of the deadliest swine diseases with haemorrhagic symptoms and a high mortality rate. Plant-derived additives are potential antiviral agents against viruses due to their environmental and user-friendly properties. This study aims to evaluate the efficacy of plant-based additives (Phyto.A04 and Phyto.B) compared to an organic acid blend (OAB) in inactivating ASF virus (ASFV) in cell culture and feed. ASFV-spiked feed was treated with individual or combined additives such as OAB, Phyto.A04 and Phyto.B. The viability of ASFV after treatment of ASFV-spiked feed with additives was then confirmed by both methods, real-time PCR and cell culture. The results of the in vitro test with cell cultures showed that all three additives (OAB, Phyto.A04 and Phyto.B) exerted a strong virucidal effect on ASFV in porcine alveolar macrophage cells. OAB at a concentration of 0.3% reduced the virus concentration from 4.48 log10 HAD50/mL after 1 day of treatment (day 1) to 3.29 log10 HAD50/mL after 3 days of treatment (day 3) and remained undetected after 7 days of treatment (day 7). In Phyto.A04 with 1%, the virus was only detectable on day 1 (3.53 log10 HAD50/mL). Phyto.B with 0.01% and 0.05% both showed good efficacy in completely inhibiting virus presence on days 3 and 7. All additives, OAB, Phyto.A04 and Phyto.B, were able to inactivate ASFV in a dose-dependent manner, as confirmed by cell culture and PCR methods. The combination of additives at different concentrations consistently improved the virucidal results.

NLRP3 deficiency improves bone healing of tooth extraction sockets through SMAD2/3-RUNX2 mediated osteoblast differentiation.

Impaired bone healing following tooth extraction poses a significant challenge for implantation. As a crucial component of the natural immune system, the NLRP3 inflammasome is one of the most extensively studied Pattern-Recognition Receptors (PRRs), and is involved in multiple diseases. Yet, the role of NLRP3 in bone healing remains to be clarified. Here, to investigate the effect of NLRP3 on bone healing, we established a maxillary first molar extraction model in wild-type (WT) and NLRP3KO mice using minimally invasive techniques. We observed that NLRP3 was activated during the bone repair phase, and its depletion enhanced socket bone formation and osteoblast differentiation. Moreover, NLRP3 inflammasome activation was found to inhibit osteogenic differentiation in alveolar bone-derived mesenchymal stem cells (aBMSCs), an effect mitigated by NLRP3 deficiency. Mechanistically, we established that SMAD2/3-RUNX2 signaling pathway is a downstream target of NLRP3 inflammasome activation, and SMAD2/3 knockdown partially reversed the significant decrease in expression of RUNX2, OSX, and ALP induced by NLRP3. Thus, our findings demonstrate that NLRP3 negatively modulates alveolar socket bone healing and contribute to the understanding of the NLRP3-induced signaling pathways involved in osteogenesis regulation.

The Complex Immune Cell Composition and Cellular Interaction in the Alveolar Compartment of Patients with Acute Respiratory Distress Syndrome.

Acute respiratory distress syndrome (ARDS) is characterized by protein rich edema due to alveolar-capillary barrier dysfunction caused by inflammatory processes. Currently, our understanding of the inflammatory response in patients with ARDS is mainly based on assessment of the systemic compartment and preclinical studies. Investigations into the intricate network of immune cells and their critical functions in the alveolar compartment remain limited. However, with recent improvements in single cell analyses, our comprehensive understanding of the interactions between immune cells in the lungs has improved. In this review, we summarize the current knowledge about the cellular composition and interactions of different immune cell types within the alveolar space of patients with ARDS. Neutrophils and macrophages are the predominant immune cells in the alveolar space of ARDS patients. Yet, all immune cells present, including lymphocytes, participate in complex interactions, coordinate recruitment, modulate the lifespan and control apoptosis through various signaling pathways. Moreover, the cellular composition of alveolar immune cells is associated with clinical outcomes of ARDS patients. In conclusion, this synthesis advances our understanding of ARDS immunology, emphasizing the crucial role of immune cells within the alveolar space. Associations between cellular composition and clinical outcomes highlight the significance of exploring distinct alveolar immune cell subsets. Such exploration holds promise for uncovering novel therapeutic targets in ARDS pathophysiology, presenting avenues for enhancing clinical management and treatment strategies for ARDS patients. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

The soluble factor milieu in idiopathic pulmonary fibrosis dysregulates epithelial differentiation.

In idiopathic pulmonary fibrosis (IPF), epithelial abnormalities are present including bronchiolization and alveolar cell dysfunction. We hypothesized that the IPF microenvironment disrupts normal epithelial growth and differentiation. We mimicked the soluble factors within an IPF microenvironment using an IPF cocktail (IPFc), composed of nine factors which are increased in IPF lungs (CCL2, IL-1β, IL-4, IL-8, IL-13, IL-33, TGF-β, TNFα, and TSLP). Using IPFc, we asked whether the soluble factor milieu in IPF affects epithelial growth and differentiation and how IPFc compares to TGF-β alone. Epithelial growth and differentiation were studied using mouse lung organoids (primary Epcam+ epithelial cells co-cultured with CCL206 fibroblasts). Organoids exposed to IPFc and TGF-β were re-sorted into epithelial and fibroblast fractions and subjected to RNA sequencing. IPFc did not affect the number of organoids formed. However, pro-surfactant protein C expression was decreased. On these parameters, TGF-β alone had similar effects. However, RNA sequencing of re-sorted organoids revealed that IPFc and TGF-β had distinct effects on both epithelial cells and fibroblasts. IPFc upregulated goblet cell markers, whereas these were inhibited by TGF-β. Although both IPFc and TGF-β increased extracellular matrix gene expression, only TGF-β increased myofibroblast markers. VEGF-C and Wnt signaling were among the most differentially regulated signaling pathways by IPFc versus TGF-β. Interestingly, Wnt pathway activation rescued Sftpc downregulation induced by IPFc. In conclusion, IPFc alters epithelial differentiation in a way that is distinct from TGF-β. Alterations in Wnt signaling contribute to these effects. IPFc may be a more comprehensive representation of the soluble factor microenvironment in IPF.

Expression of Concern: Proprotein Convertase 1/3 (PC1/3) in the Rat Alveolar Macrophage Cell Line NR8383: Localization, Trafficking and Effects on Cytokine Secretion.

Expression of Concern: Proprotein Convertase 1/3 (PC1/3) in the Rat Alveolar Macrophage Cell Line NR8383: Localization, Trafficking and Effects on Cytokine Secretion.

Viral infection induces inflammatory signals that coordinate YAP regulation of dysplastic cells in lung alveoli.

Severe viral pneumonia can induce rapid expansion of KRT5+ basal-like cells in small airways and alveoli; this forms a scar-like structure that persists in the injured alveoli and impedes normal alveolar epithelium regeneration. In this study, we investigated the mechanism by which viral infection induced this remodeling response. Through comparing different lung-injury models, we demonstrated that infection induced strong IFN-γ signal-stimulated dysplastic KRT5+ cell formation. Inactivation of interferon receptor 1 (Ifngr1) reduced dysplastic cell formation, ameliorated lung fibrosis, and improved lung-function recovery. Mechanistically, IFN-γ regulated dysplastic cell formation via the focal adhesion kinase (FAK)/Yes-associated protein 1 (YAP) pathway. Inhibiting FAK/Src diminished IFN-γ-induced YAP nuclear translocation and dysplastic cell formation. Inhibiting YAP during viral infection prevented dysplastic cell formation, whereas inhibiting YAP in persistent KRT5+ cells led to their conversion into distal club cells. Importantly, human dysplastic cells exhibited elevated FAK and YAP activity, and IFN-γ treatment promoted the transformation of human alveolar progenitor cells into dysplastic cells. These findings uncover the role of infection-induced inflammatory response in alveolar remodeling and may provide potential therapeutic avenues for the treatment of alveolar remodeling in patients with severe viral pneumonia.

Overdiagnosing giant bullous emphysema as metastatic adenocarcinoma: a case report

BackgroundGiant bullous emphysema is characterized by large bullae occupying at least one-third of the hemithorax and leading to compression of the surrounding lung parenchyma. Overdiagnosis can occur because of the atypical appearance of hyperplastic type II pneumocytes, which may be mistaken for malignant cells.Case presentationA 48-year-old male with a history of smoking and occupational exposure presented with dyspnea and drowsiness. Initial chest X-ray revealed a tension pneumothorax, and subsequent chest CT revealed extensive bullous emphysema and lung cancer in the right middle lobe (RML). Pathologic examination initially indicated resected bullae to metastatic adenocarcinoma, but upon review, it was determined that the reactive alveolar cells were misdiagnosed as malignant.ConclusionsThis case emphasizes the need for thorough histopathological assessment and prudent interpretation of atypical cellular morphology.

ACE2 Alleviates Endoplasmic Reticulum Stress and Protects against Pyroptosis by Regulating Ang1-7/Mas in Ventilator-Induced Lung Injury

Background: Ventilator-induced lung injury (VILI) is a consequence of inflammation and increased alveolar-capillary membrane permeability due to alveolar hyperdistention or elevated intrapulmonary pressure, but the precise mechanisms remain unclear. The aim of the study was to analyze the mechanism by which angiotensin converting enzyme 2 (ACE2) alleviates endoplasmic reticulum stress (ERS) and protects alveolar cells from pyroptosis in VILI by regulating angiotensin (Ang)1-7/Mas. Methods: VILI was induced in mice by mechanical ventilation by regulating the tidal volume. The alveolar cell line, A549, mimics VILI in vitro by cyclic stretch (CS). Ang (1-7) (100 nmol/L) was added to the medium. ERS was induced in cells by stimulating with tunicamycin (TM, 2 μg/mL). ERS was inhibited by tracheal instillation of 4-phenylbutyric acid (4-PBA) (1 mg/kg). ACE2's enzymatic function was activated or inhibited by subcutaneous injection of resorcinolnaphthalein (RES, 20 μg/kg) or MLN-4760 (20 μg/kg). pGLV-EF1a-GFP-ACE2 was instilled into the trachea to increase the protein expression of ACE2. The Ang (1-7) receptor, Mas, was antagonized by injecting A779 subcutaneously (80 μg/kg). Results: ACE2 protein levels decreased after modeling. Ang (1-7) level was decreased and Ang II was accumulated. ERS was significantly induced in VILI mice, and pyroptosis was observed in cells. When ERS was inhibited, pyroptosis under the VILI condition was significantly inhibited. Ang (1-7) alleviated ERS and pyroptosis under CS. When ERS was continuously activated, the function of Ang (1-7) in inhibiting pyroptosis was blocked. Resorcinolnaphthalein (RES) effectively promoted Ang II conversion, alleviated the Ang (1-7) level in VILI, ameliorated lung injury, and inhibited ERS and cell pyroptosis. Inhibiting ACE2's function in VILI hindered the production of Ang (1-7), promoted the accumulation of Ang II, and exacerbated ERS and pyroptosis, along with lung injury. The Mas antagonist significantly blocked the inhibitory effects of ACE2 on ERS and pyroptosis in VILI. Conclusions: Reduced ACE2 expression in VILI is involved in ERS and pyroptosis-related injury. ACE2 can alleviate ERS in alveolar cells by catalyzing the production of Ang (1-7), thus inhibiting pyroptosis in VILI.

Dexamethasone, Remdesivir and Azithromycin modulate ACE2 and IL-6 in Lung Epithelial Cells.

The optimal use of steroids in COVID-19 patients remains challenging. Current S3-guidelines "Recommendations for patients with COVID-19" recommend dexamethasone (DEX) for patients requiring respiratory support, remdesivir (RD) in the early disease phase and azythromycin (AZ) is no longer recommended. We investigated effects of DEX, RD and AZ in a lipopolysaccharide induced inflammation in lung cells in vitro and analyzed publicly available datasets with a focus on the Angiotensin-converting enzyme 2 (ACE2) to better understand drugs' mechanisms of action. human bronchial (Calu) and alveolar (A549) lung epithelial cells were treated with DEX, AZ or RDV in the presence of lipopolysaccharides (LPS). Gene expression (GE) of ACE2, IL-6 and the IL-6 protein release were measured. Publicly available GE data from lung tissues of COVID-19 patients and from lung cells treated with DEX were analyzed for the GE of ACE2. DEX increased and RDV and AZ reduced the GE of ACE2 in LPS-stimulated bronchial and alveolar epithelial cells. Only DEX significantly reduced LPS-induced IL-6 releases in alveolar cells substantially. The database analyses showed an, albeit not always significant, increase in ACE2 for lung tissue or cell lines treated with DEX. Lung tissue from patients after COVID-19 infection as well as bronchial cell cultures after COVID-19 infection showed lower GEs of ACE2. DEX can increase ACE2 expression in vitro and thereby the portal of entry of SARS-CoV-2 into lung cells during an LPS induced inflammation. Simultaneously the inflammatory marker IL-6 is reduced. Comparative database analyses indicate that these processes can also take place in vivo.

Enhancing safe and effective treatment of carbapenem-resistant Klebsiella pneumoniae with polymyxin B-loaded dendritic nanoparticles

Polymyxin B (PMB) is highly effective against Gram-negative bacterial infections, notably in targeting lipopolysaccharide (LPS), making it a vital last-resort treatment for carbapenem-resistant Klebsiella pneumoniae (CRKP) infections. However, its clinical application is hampered by nephrotoxicity and complications arising from its positive charge. This study introduces dendritic mesoporous organosilica nanoparticles loaded with PMB (PBSi-NPs), designed to overcome these limitations. The PBSi-NPs, with an average size of 170 nm, demonstrate effective LPS scavenging, enhanced bacterial internalization, and potent bactericidal properties. Their ability to release PMB in acidic microenvironments, characteristic of bacterial infections, significantly enhances the management of severe CRKP-induced infections. Notably, PBSi-NPs exhibit reduced toxicity towards human embryonic kidney cells (HEK 293), attributed to their stimulus-responsive design. In vivo, they exhibit higher targeting of lung cells than free PMB, specifically alveolar and bronchial cells, and effectively treat severe pneumonia in a CRKP (isolated from clinical sample) induced mouse model, markedly improving survival rates. This study proposes a novel, cost-effective method for PMB delivery using PBSi-NPs, potentially broadening the scope of nanomedicine for treating critically ill CRKP-infected patients.

The chromatin remodeler DEK promotes proliferation of mammary epithelium and is associated with H3K27me3 epigenetic modifications.

The DEK chromatin remodeling protein was previously shown to confer oncogenic phenotypes to human and mouse mammary epithelial cells using in vitro and knockout mouse models. However, its functional role in normal mammary gland epithelium remained unexplored. We developed two novel mouse models to study the role of Dek in normal mammary gland biology in vivo . Mammary gland-specific Dek over-expression in mice resulted in hyperproliferation of cells that visually resembled alveolar cells, and a transcriptional profile that indicated increased expression of cell cycle, mammary stem/progenitor, and lactation-associated genes. Conversely, Dek knockout mice exhibited an alveologenesis or lactation defect, resulting in dramatically reduced pup survival. Analysis of previously published single-cell RNA-sequencing of mouse mammary glands revealed that Dek is most highly expressed in mammary stem cells and alveolar progenitor cells, and to a lesser extent in basal epithelial cells, supporting the observed phenotypes. Mechanistically, we discovered that Dek is a modifier of Ezh2 methyltransferase activity, upregulating the levels of histone H3 trimethylation on lysine 27 (H3K27me3) to control gene transcription. Combined, this work indicates that Dek promotes proliferation of mammary epithelial cells via cell cycle deregulation. Furthermore, we report a novel function for Dek in alveologenesis and histone H3 K27 trimethylation.

Bioinspired Hyaluronic Acid‐Based Hydrogel Fuels Bi‐Directional Lung Organoid Maturation via PIEZO1 and ITGB1 Mediated Mechanosensation

AbstractLung diseases are one of the leading causes of global mortality. Advances in induced pluripotent stem cell (iPSC) differentiation have enabled the creation of bronchiolar and alveolar lung organoids, advancing research on lung conditions. Traditional Matrigel encapsulation, reliant on the spontaneous assembly and propagation of cells with limited external intervention, often results in variability and low reproducibility. The absence of hyaluronic acid (HA) in Matrigel, a key lung extracellular matrix component, limits bronchiolar and alveolar cell differentiation, reducing the efficacy and reproducibility of iPSC‐derived organoid generation. To address this, a novel hybrid hydrogel combining HA and 23% Matrigel, inspired by the natural lung environment, is developed. This hydrogel offers improved biochemical support and viscoelastic properties, significantly accelerating organoid development. Within eight days, the hydrogel produces uniformly sized organoids containing both bronchiolar and alveolar epithelial cells. Increased levels of active mechanosensors and transducers, including PIEZO1, Integrin, and Myosin, suggest that the hydrogel's altered viscoelasticity triggers a mechanotransduction cascade. This bioinspired hydrogel provides a robust, fast model for biomedical research, facilitating rapid drug screening, respiratory disease treatment studies, and surfactant trafficking investigations. Furthermore, it enables the exploration of underlying biomechanical mechanisms to enhance the controllability of organoid generation and maturation.