HER2 activation results in β-catenin-dependent changes in pulmonary epithelial permeability

Regeneration capability of neonatal lung-derived decellularized extracellular matrix in an emphysema model

Impaired and limited alveolar regeneration upon injury advances pulmonary disorders and irreversibly affects millions of people worldwide. Adult mammals do not have a strong potential to regenerate functional lung tissues, while neonatal lungs robustly proliferate and regenerate the functional tissue within a week of birth upon injury. The differential composition of the extracellular matrix (ECM) of neonatal tissues favors cellular proliferation and migration, fostering lung regeneration. Regardless, conventional ECM therapies employ adult-derived tissues. Therefore, the potential differences in regenerative properties of adult and neonatal lung ECM were investigated using in vitro and in vivo lung emphysema model. Decellularization of the neonatal and adult lungs was performed using freeze-thaw cycle method. Decellularization process was structurally characterized using SEM and immunostaining. In vitro treatment of neonatal lung-derived ECM (NECM) significantly enhanced the cellular migration and proliferation compared to adult-lung derived ECM (AECM) treated cigarette smoke-extract (CSE)-stimulated A549 cells. Following the administration of AECM and NECM, we observed a significant decline in emphysematous features and an improvement in lung functions in NECM group. NECM treatment increased the ratio of HOPX+/SpC+ cells with an active proliferation in SpC+ cells shown by colocalization of SpC+/Ki67+ and SpC+/Brdu+ cells. Moreover, NECM treatment activated the Neureguline-1/Erbb2 signaling and fostered a regenerative environment by upregulating the expression of regenerative genes including FGF, WNTs and AXIN-2 as compared to AECM treatment. Our findings suggested the potential utilization of NECM as novel therapeutics in regenerative medicine, deviating from the conventional application of adult-derived ECM treatments in pre-clinical and clinical research.

Bufei Yishen formula protects the airway epithelial barrier and ameliorates COPD by enhancing autophagy through the Sirt1/AMPK/Foxo3 signaling pathway

OBJECT

Bufei Yishen formula (BYF), a traditional Chinese medicine alleviates COPD symptoms and suppresses airway epithelial inflammation. In this study, we determined whether BYF protects the airway epithelial barrier from destruction in COPD rats.

METHODS

The protective effects of BYF on the airway epithelial barrier were examined in a rat COPD model. BEAS-2B epithelial cells were exposed to cigarette smoke extract (CSE) to determine the effect of BYF on epithelial barrier function. Transcriptomic and network analyses were conducted to identify the protective mechanisms.

RESULTS

Oral BYF reduced the severity of COPD in rats by suppressing the decline in lung function, pathological changes, inflammation, and protected airway epithelial barrier function by upregulating apical junction proteins, including occludin (OCLN), zonula occludens (ZO)-1, and E-cadherin (E-cad). BYF treatment reduced epithelial permeability, and increased TEER as well as the apical junction proteins, OCLN, ZO-1, and E-cad in BEAS-2B cells exposed to CSE. Furthermore, 58 compounds identified in BYF were used to predict 421 potential targets. In addition, the expression of 572 differentially expressed genes (DEGs) was identified in CSE-exposed BEAS-2B cells. A network analysis of the 421 targets and 572 DEGs revealed that BYF regulates multiple pathways, of which the Sirt1, AMPK, Foxo3, and autophagy pathways may be the most important with respect to protective mechanisms. Moreover, in vitro experiments confirmed that nobiletin, one of the active compounds in BYF, increased apical junction protein levels, including OCLN, ZO-1, and E-cad. It also increased LC3B and phosphorylated AMPK levels and decreased the phosphorylation of FoxO3a.

CONCLUSIONS

BYF protects the airway epithelial barrier in COPD by enhancing autophagy through regulation of the SIRT1/AMPK/FOXO3 signaling pathway.

Maintenance of airway epithelial barrier integrity via the inhibition of AHR/EGFR activation ameliorates chronic obstructive pulmonary disease using effective-component combination

BACKGROUND

Airway epithelial barrier dysfunction is highly related to the pathogenesis of chronic obstructive pulmonary disease (COPD). Effective-component combination (ECC) derived from Bufei Yishen formula (BYF) is an effective treatment regimen for patients with COPD and has previously been found to attenuate COPD and airway epithelial inflammation in rats.

PURPOSE

To determine the mechanism underlying the protective effects of ECC-BYF against the disruption of the airway epithelial barrier in COPD.

METHODS

The protective effects of ECC-BYF on the airway epithelial barrier were investigated in a rat COPD model. BEAS-2B epithelial cells were stimulated with cigarette smoke extract (CSE) to determine the direct effects of ECC-BYF on epithelial barrier function and aryl hydrocarbon receptor (AHR)/ epidermal growth factor receptor (EGFR) signaling.

RESULTS

The results revealed that ECC-BYF attenuated COPD in rats and maintained the airway epithelial barrier by upregulating the expression of apical junction proteins, including occludin (OCC), zonula occludens (ZO)-1, and E-cadherin (E-cad). In BEAS-2B cells, ECC-BYF decreased permeability, increased transepithelial electrical resistance, and prevented the decrease in OCC, ZO-1, and E-cad expression induced by CSE exposure. In addition, transcriptomics and network analysis revealed that the protective effects of ECC-BYF may be related to multiple signaling pathways, including ErbB, AHR, and PI3K-Akt-mTOR pathways. ECC-BYF treatment suppressed the protein levels of p-EGFR and p-ERK1/2 and mRNA levels of CYP1A1 in CSE-exposed BEAS-2B cells as well as the protein levels of p-EGFR, p-ERK1/2, and CYP1A1 in the lungs of rats with COPD. In BEAS-2B cells, the AHR agonist FICZ weakened the protective effect of ECC-BYF on the epithelial barrier by suppressing the increase in ZO-1 and OCC expression induced by ECC-BYF and preventing the inhibitory effects of ECC-BYF on EGFR phosphorylation.

CONCLUSIONS

This is the first study to demonstrate the protective effect of ECC-BYF on airway epithelial barrier function. The underlying mechanism may be associated with the suppression of the AHR/EGFR pathway to promote apical junction protein adhesion.

Anticancer pan-ErbB inhibitors reduce inflammation and tissue injury and exert broad-spectrum antiviral effects

Targeting host factors exploited by multiple viruses could offer broad-spectrum solutions for pandemic preparedness. Seventeen candidates targeting diverse functions emerged in a screen of 4,413 compounds for SARS-CoV-2 inhibitors. We demonstrated that lapatinib and other approved inhibitors of the ErbB family receptor tyrosine kinases suppress replication of SARS-CoV-2, Venezuelan equine encephalitis virus (VEEV), and other emerging viruses with a high barrier to resistance. Lapatinib suppressed SARS-CoV-2 entry and later stages of the viral life cycle and showed synergistic effect with the direct-acting antiviral nirmatrelvir. We discovered that ErbB1, 2 and 4 bind SARS-CoV-2 S1 protein and regulate viral and ACE2 internalization, and they are required for VEEV infection. In human lung organoids, lapatinib protected from SARS-CoV-2-induced activation of ErbB-regulated pathways implicated in non-infectious lung injury, pro-inflammatory cytokine production, and epithelial barrier injury. Lapatinib suppressed VEEV replication, cytokine production and disruption of the blood-brain barrier integrity in microfluidic-based human neurovascular units, and reduced mortality in a lethal infection murine model. We validated lapatinib-mediated inhibition of ErbB activity as an important mechanism of antiviral action. These findings reveal regulation of viral replication, inflammation, and tissue injury via ErbBs and establish a proof-of-principle for a repurposed, ErbB-targeted approach to combat emerging viruses.

Role of air pollutants in airway epithelial barrier dysfunction in asthma and COPD

Chronic exposure to environmental pollutants is a major contributor to the development and progression of obstructive airway diseases, including asthma and COPD. Understanding the mechanisms underlying the development of obstructive lung diseases upon exposure to inhaled pollutants will lead to novel insights into the pathogenesis, prevention and treatment of these diseases. The respiratory epithelial lining forms a robust physicochemical barrier protecting the body from inhaled toxic particles and pathogens. Inhalation of airborne particles and gases may impair airway epithelial barrier function and subsequently lead to exaggerated inflammatory responses and airway remodelling, which are key features of asthma and COPD. In addition, air pollutant-induced airway epithelial barrier dysfunction may increase susceptibility to respiratory infections, thereby increasing the risk of exacerbations and thus triggering further inflammation. In this review, we discuss the molecular and immunological mechanisms involved in physical barrier disruption induced by major airborne pollutants and outline their implications in the pathogenesis of asthma and COPD. We further discuss the link between these pollutants and changes in the lung microbiome as a potential factor for aggravating airway diseases. Understanding these mechanisms may lead to identification of novel targets for therapeutic intervention to restore airway epithelial integrity in asthma and COPD.

Exposure to air pollution induces airway epithelial barrier dysfunction through several mechanisms including increased oxidative stress, exaggerated cytokine responses and impaired host defence, which contributes to development of asthma and COPD. https://bit.ly/3DHL1CA

Nuclear translocation of β-catenin induced by E-cadherin endocytosis causes recurrent erosion of diabetic cornea

Recurrent epithelial erosion and refractory corneal ulcer are the clinical features of diabetic keratopathy (DK), which eventually lead to corneal scar and visual disturbance. In this study, we sought to determine the abnormalities of cell junction in diabetic corneal epithelial cells and the effect of high glucose on the β-catenin/E-cadherin complex. Corneal histology showed that corneal epithelial cells of high glucose mice were loosely arranged, and the immunohistochemistry showed that the expression of E-cadherin decreased, the levels of β-catenin increased in nuclear. High glucose-induced degradation and endocytosis of E-cadherin of corneal epithelial cells reduce the formation of β-catenin/E-cadherin complex and promote the nuclear translocation of β-catenin. Moreover, high glucose also activated the transcription and expression of matrix metallopeptidase and snail, which interfered with the adhesion of corneal epithelial cells to the basement membrane. These findings reveal that DK is associated with the dissociation of cell junctions. The maintenance of the stability of the β-catenin/E-cadherin complex may be a potential therapeutic target of refractory corneal ulcers in patients with diabetes.

Role of mTOR As an Essential Kinase in SCLC

OBJECTIVES

SCLC represents 15% of all lung cancer diagnoses in the United States and has a particularly poor prognosis. We hypothesized that kinases regulating SCLC survival pathways represent therapeutically targetable vulnerabilities whose inhibition may improve SCLC outcome.

METHODS

A short-hairpin RNA (shRNA) library targeting all human kinases was introduced in seven chemonaive patient-derived xenografts (PDX) and the cells were cultured in vitro and in vivo. On harvest, lost or depleted shRNAs were considered as regulating-cell survival pathways and deemed essential kinases.

RESULTS

Unsupervised hierarchical cluster analysis of recovered shRNAs separated the PDXs into two clusters, suggesting kinase-based heterogeneity among the SCLC PDXs. A total of 23 kinases were identified as essential in two or more PDXs, with mechanistic Target of Rapamycin (mTOR) a candidate essential kinase in four. mTOR phosphorylation status correlated with PDX sensitivity to mTOR kinase inhibition, and mTOR inhibition sensitized the PDX to cisplatin and etoposide. In the PDX in which mTOR was defined as essential, mTOR inhibition caused a 43% decrease in tumor volume at 21 days (p < 0.01). Combining mTOR inhibition with cisplatin and etoposide decreased PDX tumor volume 96% compared with cisplatin and etoposide alone at 70 days (p < 0.002). Chemoresistance did not develop with the combination of mTOR inhibition and cisplatin and etoposide in mTOR-essential PDX over 105 days. The prevalence of phospho-mTOR-Ser-2448 in a tissue microarray of chemonaive SCLC was 27%, thus, identifying an important SCLC subtype that might benefit from the addition of mTOR inhibition to standard chemotherapy.

CONCLUSIONS

These studies reveal that kinases can define SCLC subgroups, can identify therapeutic vulnerabilities, and can potentially be used to optimize therapeutic approaches. Significance We used functional genomics to identify kinases regulating SCLC survival. mTOR was identified as essential in a subset of PDXs. mTOR inhibition decreased PDX growth, sensitized PDX to cisplatin and etoposide, and prevented chemoresistance.

The IL1β-HER2-CLDN18/CLDN4 axis mediates lung barrier damage in ARDS

Objective: The high mortality rate associated with acute respiratory distress syndrome (ARDS) is a major challenge for intensive care units. In the present study, we applied bioinformatics and animal models to identify core genes and potential corresponding pathways in ARDS.

Results: Using bioinformatics analysis, IL-1β was identified as the core gene of ARDS. Cell experiments showed that up-regulation of IL-1β downregulates claudin18 to promote lung barrier function damage by regulating the IL-1β-HER2/HER3 axis, further promoting the development of ARDS. This was validated in the animal models.

Conclusion: IL-1β promotes the development of ARDS by regulating the IL-1β-HER2/HER3 axis. These findings deepen the understanding of the pathological mechanisms of ARDS.

Methods: Transcription data sets related to ARDS were subjected to differential expression gene analysis, functional enrichment analysis, and receiver operating characteristic curve analysis and, so as to identify core genes in ARDS. Cell experiments were used to further explore the effects of core genes on lung barrier function damage. Animal models were applied to validate the effects of core gene in mediating biological signal pathways in ARDS.

Macrophages as an Emerging Source of Wnt Ligands: Relevance in Mucosal Integrity

The Wnt signaling pathway is a conserved pathway involved in important cellular processes such as the control of embryonic development, cellular polarity, cellular migration, and cell proliferation. In addition to playing a central role during embryogenesis, this pathway is also an essential part of adult homeostasis. Indeed, it controls the proliferation of epithelial cells in different organs such as intestine, lung, and kidney, and guarantees the maintenance of the mucosa in physiological conditions. The origin of this molecular pathway is the binding between Wnt ligands (belonging to a family of 19 different homologous secreted glycoproteins) and their specific membrane receptors, from the Frizzled receptor family. This specific interaction triggers the activation of the signaling cascade, which in turn activates or suppresses the expression of different genes in order to change the behavior of the cell. On the other hand, alterations of this pathway have been described in pathological conditions such as inflammation, fibrosis, and cancer. In recent years, macrophages-among other cell types-have emerged as a potential source of Wnt ligands. Due to their high plasticity, macrophages, which are central to the innate immune response, are capable of adopting different phenotypes depending on their microenvironment. In the past, two different phenotypes were described: a proinflammatory phenotype-M1 macrophages-and an anti-inflammatory phenotype-M2 macrophages-and a selective expression of Wnt ligands has been associated with said phenotypes. However, nowadays it is assumed that macrophages in vivo move through a continual spectrum of functional phenotypes. In both physiological and pathological (inflammation, fibrosis and cancer) conditions, the accumulation and polarization of macrophages conditions the future of the tissue, facilitating various scenarios, such as resolution of inflammation, activation of fibrosis, and cancer development due to the modulation of the Wnt signaling pathway, in autocrine and paracrine manner. In this work, we provide an overview of studies that have explored the role of macrophages and how they act as a source of Wnt ligands and as mediators of mucosal integrity.

Interleukin-6 is required for Neuregulin-1 induced HER2 signaling in lung epithelium

A clear understanding of the mechanisms that regulate the alveolar epithelium's barrier is critical to develop new therapeutic strategies to mitigate lung injury. The HER2/HER3 receptor tyrosine kinase complex plays a central role in maintaining the alveolar-capillary barrier. This receptor complex is activated by its ligand, neuregulin-1 (NRG-1). Interleukin-6 (IL-6) is also known to induce HER2 signaling through HER2 transphosphorylation by the IL-6 receptor (IL-6R) complex (1). Due to this interaction, we hypothesized that NRG-1 and IL-6 cooperatively interacted to activate the HER2/HER3 complex. Studies were performed in cultured pulmonary epithelial cells measuring the HER2/IL-6/IL-6R/GP130 interaction and receptor activation by western blotting and confocal microscopy, IL-6 production by ELISA, and IL-6 inhibition using specific antibodies, small molecule inhibitors and shRNA. We found that IL-6 was required for NRG-1 induced activation of HER2 in pulmonary epithelial cells. IL-6 inhibition led to a decrease in NRG-1 induced HER2 activation. The IL-6R and GP130, a subunit of the IL-6R complex, were physically associated with HER2 and were required for NRG-1 induced HER2 activation. Inhibition of GP130, the β-subunit of the IL-6 receptor decreased NRG-1 induced HER2 activation lower than control by 38% Finally, HER2 activation increased IL-6 secretion more than two-fold over resting cells (526 ± 131 vs 231 ± 39.7 pg/ml), and inhibition of HER2 gene expression decreased basal IL-6 secretion over 80% (89 + 4.6 vs 1.3 + 0.8 pg/ml). These findings identify a requirement for IL-6 and the IL-6R complex to allow NRG-1 mediated HER2 activation, and a HER2 driven IL-6 production feedback loop.

Penfluridol overcomes paclitaxel resistance in metastatic breast cancer

Paclitaxel is a first line chemotherapeutic agent for the patients with metastatic breast cancer. But inherited or acquired resistance to paclitaxel leads to poor response rates in a majority of these patients. To identify mechanisms of paclitaxel resistance, we developed paclitaxel resistant breast cancer cell lines, MCF-7 and 4T1 by continuous exposure to paclitaxel for several months. Western blot analysis showed increased expression of HER2 and β-catenin pathway in resistant cell lines as compared to parent cells. Hence, we hypothesized that HER2/β-catenin mediates paclitaxel resistance in breast cancer and suppression of HER2/β-catenin signaling could overcome paclitaxel resistance. Our data showed that penfluridol (PFL) treatment significantly reduced the survival of paclitaxel-resistant cells. Western blot analysis revealed that PFL treatment suppressed HER2, as well as, β-catenin pathway. In vivo data confirmed that PFL significantly potentiated tumor growth suppressive effects of paclitaxel in an orthotropic breast cancer model. In addition, tumors from paclitaxel and PFL-treated mice showed reduced HER2 and β-catenin expression, along with increased apoptosis. Taken together our results demonstrate a novel role of HER2/β-catenin in paclitaxel resistance and open up new avenues for application of PFL as a therapeutic option for overcoming paclitaxel resistance.

HER2 Signaling Implicated in Regulating Alveolar Epithelial Permeability with Cyclic Stretch

Mechanical ventilation can be damaging, and can cause or exacerbate ventilator-induced lung injury (VILI). The human epidermal growth factor receptor (HER) ligand neuregulin-1 (NRG1) activates HER2 heterodimerization with HER3, and has been implicated in inflammatory injuries. We hypothesized that HER2 activation contributes to VILI. We analyzed a database of differentially expressed genes between cyclically stretched and unstretched rat alveolar epithelial cells (RAEC) for HER ligands and validated the differential expression. The effect of the ligand and HER2 inhibition on RAEC permeability was tested, and in vivo relevance was assessed in a rat model of VILI. Analysis of our expression array revealed the upregulation of NRG1 and amphiregulin (AREG) with stretch. NRG1 protein, but not AREG, increased after stretch in culture media. Treatment with an NRG1-cleavage inhibitor (TAPI2) or an inhibitor of NRG1-binding (anti-HER3 antibody) reduced HER2 phosphorylation and partially mitigated stretch-induced permeability, with the upregulation of claudin-7. The results were reproduced by treatment with a direct inhibitor of HER2 phosphorylation (AG825). The transfection of microRNA miR-15b, predicted to negatively regulate NRG1, also attenuated stretch-induced permeability, and was associated with lower NRG1 mRNA levels. In rats ventilated at damaging tidal volumes, AG825 partly attenuated VILI. We concluded that cyclic stretch activates HER2 via the HER3 ligand NRG1, leading to increased permeability. Outcomes were mitigated by the downregulation of NRG1, prevention of NRG1 binding, and most strongly by the direct inhibition of HER2. In vivo HER2 inhibition also attenuated VILI. Ligand-dependent HER2 activation is a potential target for reducing VILI.

Recognition of HER2 expression in hepatocellular carcinoma and its significance in postoperative tumor recurrence

Background

The ERBB2 oncogene hypothesis is challenged in hepatocellular carcinoma (HCC) with the conflicting evidences of human epidermal growth factor receptor 2 (HER2) overexpression. HER2 could be a new target as a treatment option for HCC as well as tumor recurrence after surgery. HER2 in HCC biology needs further explorations.

Methods

Clinical and mRNA data of HCC patients were obtained from TCGA HCC cohort, GSE89377 and GSE115018. Western Blotting and immunohistochemistry were employed to test expression of HER2, E‐cadherin, and Vimentin. In HepG2, JM1, HER2‐transfected McA cells, and TGF‐β cocultured JM1 cells, HCC biology, including cell survival, proliferation, and epithelial‐to‐mesenchymal transition (EMT) phenotypes were evaluated.

Results

ERBB2 mRNA amplification was found in HCC datasets, and its expression was downregulated in high grade HCC with a worse overall survival. HER2 overexpression was identified in H4IIE, HepG2, JM1 cells, and 82% (14/17) HCC samples, and tumor stage was correlated with expression of HER2, E‐cadherin, and Vimentin (P < 0.05). Trastuzumab with the high concentrations suppressed proliferation of HER2‐positive hepatoma cells (P < 0.05); in the coculture model to induce EMT of JM1 cells, HER2 expression increased with downregulated E‐cadherin and upregulated Vimentin. Trastuzumab intravenous injection inhibited in vivo tumor size and metastases (P < 0.05). Signal analysis revealed that HER2 functioned through upregulation of β‐catenin and inhibition of SMAD3.

Conclusion

HER2 expression pattern is linked with tumor stage and overall survival; the transforming function of HER2 is found more relevant through β‐catenin and SMAD3. HER2‐targeted treatment is recommended to suppress the HER2‐mediated tumor growth during postoperative liver regeneration.

Wnt/β-catenin signaling links embryonic lung development and asthmatic airway remodeling

Embryonic lung development requires reciprocal endodermal-mesodermal interactions; mediated by various signaling proteins. Wnt/β-catenin is a signaling protein that exhibits the pivotal role in lung development, injury and repair while aberrant expression of Wnt/β-catenin signaling leads to asthmatic airway remodeling: characterized by hyperplasia and hypertrophy of airway smooth muscle cells, alveolar and vascular damage goblet cells metaplasia, and deposition of extracellular matrix; resulting in decreased lung compliance and increased airway resistance. The substantial evidence suggests that Wnt/β-catenin signaling links embryonic lung development and asthmatic airway remodeling. Here, we summarized the recent advances related to the mechanistic role of Wnt/β-catenin signaling in lung development, consequences of aberrant expression or deletion of Wnt/β-catenin signaling in expansion and progression of asthmatic airway remodeling, and linking early-impaired pulmonary development and airway remodeling later in life. Finally, we emphasized all possible recent potential therapeutic significance and future prospectives, that are adaptable for therapeutic intervention to treat asthmatic airway remodeling.

Cigarette Smoke Induces Human Epidermal Receptor 2-Dependent Changes in Epithelial Permeability

The airway epithelium constitutes a protective barrier against inhaled insults, such as viruses, bacteria, and toxic fumes, including cigarette smoke (CS). Maintenance of bronchial epithelial integrity is central for airway health, and defective epithelial barrier function contributes to the pathogenesis of CS-mediated diseases, such as chronic obstructive pulmonary disease. Although CS has been shown to increase epithelial permeability, current understanding of the mechanisms involved in CS-induced epithelial barrier disruption remains incomplete. We have previously identified that the receptor tyrosine kinase human epidermal receptor (HER) 2 growth factor is activated by the ligand neuregulin-1 and increases epithelial permeability in models of inflammatory acute lung injury. We hypothesized that CS activates HER2 and that CS-mediated changes in barrier function would be HER2 dependent in airway epithelial cells. We determined that HER2 was activated in whole lung, as well as isolated epithelial cells, from smokers, and that acute CS exposure resulted in HER2 activation in cultured bronchial epithelial cells. Mechanistic studies determined that CS-mediated HER2 activation is independent of neuregulin-1 but required upstream activation of the epidermal growth factor receptor. HER2 was required for CS-induced epithelial permeability as knockdown of HER2 blocked increases in permeability after CS. CS caused an increase in IL-6 production by epithelial cells that was dependent on HER2-mediated extracellular signal-regulated kinases (Erk) activation. Finally, blockade of IL-6 attenuated CS-induced epithelial permeability. Our data indicate that CS activates pulmonary epithelial HER2 and that HER2 is a central mediator of CS-induced epithelial barrier dysfunction.