Transforming growth factor-alpha deficiency reduces pulmonary fibrosis in transgenic mice

Ovarian sex steroid and epithelial control of immune responses in the uterus and oviduct: human and animal models†

The female reproductive tract (FRT), including the uterus and oviduct (Fallopian tube), is responsible for maintaining an optimal microenvironment for reproductive processes, such as gamete activation and transportation, sperm capacitation, fertilization, and early embryonic and fetal development. The mucosal surface of the FRT may be exposed to pathogens and sexually transmitted microorganisms due to the opening of the cervix during mating. Pathogens and endotoxins may also reach the oviduct through the peritoneal fluid. To maintain an optimum reproductive environment while recognizing and killing pathogenic bacterial and viral agents, the oviduct and uterus should be equipped with an efficient and rigorously controlled immune system. Ovarian sex steroids can affect epithelial cells and underlying stromal cells, which have been shown to mediate innate and adaptive immune responses. This, in turn, protects against potential infections while maintaining an optimal milieu for reproductive events, highlighting the homeostatic involvement of ovarian sex steroids and reproductive epithelial cells. This article will discuss how ovarian sex steroids affect the immune reactions elicited by the epithelial cells of the non-pregnant uterus and oviduct in the bovine, murine, and human species. Finally, we propose that there are regional and species-specific differences in the immune responses in FRT.

TGFA expression is associated with poor prognosis and promotes the development of cervical cancer

Cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) are the second most common cancers in women aged 20-39. While HPV screening can help with early detection of cervical cancer, many patients are already in the medium to late stages when they are identified. As a result, searching for novel biomarkers to predict CESC prognosis and propose molecular treatment targets is critical. TGFA is a polypeptide growth factor with a high affinity for the epidermal growth factor receptor. Several studies have shown that TGFA can improve cancer growth and progression, but data on its impact on the occurrence and advancement of CESC is limited. In this study, we used clinical data analysis and bioinformatics techniques to explore the relationship between TGFA and CESC. The results showed that TGFA was highly expressed in cervical cancer tissues and cells. TGFA knockdown can inhibit the proliferation, migration and invasion of cervical cancer cells. In addition, after TGFA knockout, the expression of IL family and MMP family proteins in CESC cell lines was significantly reduced. In conclusion, TGFA plays an important role in the occurrence and development of cervical cancer. Therefore, TGFA may become a new target for cervical cancer treatment.

Amelioration of Pulmonary Fibrosis by Matrix Metalloproteinase-2 Overexpression

Idiopathic pulmonary fibrosis is a progressive and fatal disease with a poor prognosis. Matrix metalloproteinase-2 is involved in the pathogenesis of organ fibrosis. The role of matrix metalloproteinase-2 in lung fibrosis is unclear. This study evaluated whether overexpression of matrix metalloproteinase-2 affects the development of pulmonary fibrosis. Lung fibrosis was induced by bleomycin in wild-type mice and transgenic mice overexpressing human matrix metalloproteinase-2. Mice expressing human matrix metalloproteinase-2 showed significantly decreased infiltration of inflammatory cells and inflammatory and fibrotic cytokines in the lungs compared to wild-type mice after induction of lung injury and fibrosis with bleomycin. The computed tomography score, Ashcroft score of fibrosis, and lung collagen deposition were significantly reduced in human matrix metalloproteinase transgenic mice compared to wild-type mice. The expression of anti-apoptotic genes was significantly increased, while caspase-3 activity was significantly reduced in the lungs of matrix metalloproteinase-2 transgenic mice compared to wild-type mice. Active matrix metalloproteinase-2 significantly decreased bleomycin-induced apoptosis in alveolar epithelial cells. Matrix metalloproteinase-2 appears to protect against pulmonary fibrosis by inhibiting apoptosis of lung epithelial cells.

Epiregulin is a dendritic cell-derived EGFR ligand that maintains skin and lung fibrosis

Immune cells are fundamental regulators of extracellular matrix (ECM) production by fibroblasts and have important roles in determining extent of fibrosis in response to inflammation. Although much is known about fibroblast signaling in fibrosis, the molecular signals between immune cells and fibroblasts that drive its persistence are poorly understood. We therefore analyzed skin and lung samples of patients with diffuse cutaneous systemic sclerosis, an autoimmune disease that causes debilitating fibrosis of the skin and internal organs. Here, we define a critical role of epiregulin-EGFR signaling between dendritic cells and fibroblasts to maintain elevated ECM production and accumulation in fibrotic tissue. We found that epiregulin expression marks an inducible state of DC3 dendritic cells triggered by type I interferon and that DC3-derived epiregulin activates EGFR on fibroblasts, driving a positive feedback loop through NOTCH signaling. In mouse models of skin and lung fibrosis, epiregulin was essential for persistence of fibrosis in both tissues, which could be abrogated by epiregulin genetic deficiency or a neutralizing antibody. Therapeutic administration of epiregulin antibody reversed fibrosis in patient skin and lung explants, identifying it as a previously unexplored biologic drug target. Our findings reveal epiregulin as a crucial immune signal that maintains skin and lung fibrosis in multiple diseases and represents a promising antifibrotic target.

Modeling Kaempferol as a Potential Pharmacological Agent for COVID-19/PF Co-Occurrence Based on Bioinformatics and System Pharmacological Tools

Objective: People suffering from coronavirus disease 2019 (COVID-19) are prone to develop pulmonary fibrosis (PF), but there is currently no definitive treatment for COVID-19/PF co-occurrence. Kaempferol with promising antiviral and anti-fibrotic effects is expected to become a potential treatment for COVID-19 and PF comorbidities. Therefore, this study explored the targets and molecular mechanisms of kaempferol against COVID-19/PF co-occurrence by bioinformatics and network pharmacology.

Methods: Various open-source databases and Venn Diagram tool were applied to confirm the targets of kaempferol against COVID-19/PF co-occurrence. Protein-protein interaction (PPI), MCODE, key transcription factors, tissue-specific enrichment, molecular docking, Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to clarify the influential molecular mechanisms of kaempferol against COVID-19 and PF comorbidities.

Results: 290 targets and 203 transcription factors of kaempferol against COVID-19/PF co-occurrence were captured. Epidermal growth factor receptor (EGFR), proto-oncogene tyrosine-protein kinase SRC (SRC), mitogen-activated protein kinase 3 (MAPK3), mitogen-activated protein kinase 1 (MAPK1), mitogen-activated protein kinase 8 (MAPK8), RAC-alpha serine/threonine-protein kinase (AKT1), transcription factor p65 (RELA) and phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha isoform (PIK3CA) were identified as the most critical targets, and kaempferol showed effective binding activities with the above critical eight targets. Further, anti-COVID-19/PF co-occurrence effects of kaempferol were associated with the regulation of inflammation, oxidative stress, immunity, virus infection, cell growth process and metabolism. EGFR, interleukin 17 (IL-17), tumor necrosis factor (TNF), hypoxia inducible factor 1 (HIF-1), phosphoinositide 3-kinase/AKT serine/threonine kinase (PI3K/AKT) and Toll-like receptor signaling pathways were identified as the key anti-COVID-19/PF co-occurrence pathways.

Conclusion: Kaempferol is a candidate treatment for COVID-19/PF co-occurrence. The underlying mechanisms may be related to the regulation of critical targets (EGFR, SRC, MAPK3, MAPK1, MAPK8, AKT1, RELA, PIK3CA and so on) and EGFR, IL-17, TNF, HIF-1, PI3K/AKT and Toll-like receptor signaling pathways. This study contributes to guiding development of new drugs for COVID-19 and PF comorbidities.

EGFR Signaling in Lung Fibrosis

In this review article, we will first provide a brief overview of the ErbB receptor-ligand system and its importance in developmental and physiological processes. We will then review the literature regarding the role of ErbB receptors and their ligands in the maladaptive remodeling of lung tissue, with special emphasis on idiopathic pulmonary fibrosis (IPF). Here we will focus on the pathways and cellular processes contributing to epithelial-mesenchymal miscommunication seen in this pathology. We will also provide an overview of the in vivo studies addressing the efficacy of different ErbB signaling inhibitors in experimental models of lung injury and highlight how such studies may contribute to our understanding of ErbB biology in the lung. Finally, we will discuss what we learned from clinical applications of the ErbB1 signaling inhibitors in cancer in order to advance clinical trials in IPF.

The Transcription Factor FRA-1/AP-1 Controls Lipocalin-2 Expression and Inflammation in Sepsis Model

Sepsis is a life-threatening condition characterized by excessive inflammation in its early phase. This is followed by an aberrant resolution phase associated to a prolonged period of immune suppression that can ultimately lead to multiple organ dysfunctions. This immunosuppression can be mediated by the functional reprogramming of gene transcription in monocytes/macrophages in response to prolonged lipopolysaccharide (LPS) exposure. Surprisingly, there is no report on the role of AP-1 transcription factors in this reprogramming process. Herein, we used the endotoxin tolerance model on murine bone marrow-derived macrophages in which tolerant cells stimulated twice with LPS were compared to naïve cells stimulated once. Out of all AP-1 transcription factors tested, Fosl1 gene stood out because of its unique regulation in tolerized cells. Moreover, we could correlate FRA-1 expression to the expression of an essential anti-inflammatory molecule involved in sepsis response, Lipocalin 2 aka NGAL. Identical results were obtained in human PBMC following the endotoxin tolerance model. When using FRA-1 deficient macrophages, we could confirm that FRA-1 regulates NGAL expression during the tolerant state. Interestingly, ChIP-seq and ChIP-qPCR revealed the binding of FRA-1 on Lcn2 promoter after LPS stimulation in these cells. Finally, we used an in vivo septic model of consecutive injection of LPS, in which the second stimulation is performed before the resolution of inflammation, in wild type and FRA-1 deficient mice. NGAL secretion was elevated in lung, spleen and serum of wild type tolerant mice, whereas it was significantly lower in tolerant FRA-1 deficient mice. Moreover, an increased inflammatory state likely dependent of the low level of NGAL was observed in these FRA-1 deficient mice. This was characterized by an increase of neutrophil infiltration in lung and an increase of apoptotic follicular cells in spleen. This suggests that FRA-1 expression supports resolution of inflammation in this model. Collectively, our data indicate that FRA-1 is involved in myeloid cell tolerance responses by mediating the functional reprogramming of Lcn2 transcription in response to prolonged LPS exposure. In conclusion, FRA-1 may have a protective role in the tolerance response of sepsis through the regulation of NGAL, leading to resolution of inflammation.

Quantitative Proteomic Analysis in Alveolar Type II Cells Reveals the Different Capacities of RAS and TGF-β to Induce Epithelial-Mesenchymal Transition

Alveolar type II (ATII) epithelial cells function as stem cells, contributing to alveolar renewal, repair and cancer. Therefore, they are a highly relevant model for studying a number of lung diseases, including acute injury, fibrosis and cancer, in which signals transduced by RAS and transforming growth factor (TGF)-β play critical roles. To identify downstream molecular events following RAS and/or TGF-β activation, we performed proteomic analysis using a quantitative label-free approach (LC-HDMS^E) to provide in-depth proteome coverage and estimates of protein concentration in absolute amounts. Data are available via ProteomeXchange with identifier PXD023720. We chose ATII^ER:KRASV12 as an experimental cell line in which RAS is activated by adding 4-hydroxytamoxifen (4-OHT). Proteomic analysis of ATII cells treated with 4-OHT or TGF-β demonstrated that RAS activation induces an epithelial–mesenchymal transition (EMT) signature. In contrast, under the same conditions, activation of TGF-β signaling alone only induces a partial EMT. EMT is a dynamic and reversible biological process by which epithelial cells lose their cell polarity and down-regulate cadherin-mediated cell–cell adhesion to gain migratory properties, and is involved in embryonic development, wound healing, fibrosis and cancer metastasis. Thus, these results could help to focus research on the identification of processes that are potentially driving EMT-related human disease.

Muc5b-deficient mice develop early histological lung abnormalities

Gel-forming mucins are the main organic component responsible for physical properties of the mucus hydrogels. While numerous biological functions of these mucins are well documented, specific physiological functions of each mucin are largely unknown. To investigate in vivo functions of the gel-forming mucin Muc5b, which is one of the major secreted airway mucins, along with Muc5ac, we generated mice in which Muc5b was disrupted and maintained in the absence of environmental stress. Adult Muc5b-deficient mice displayed bronchial hyperplasia and metaplasia, interstitial thickening, alveolar collapse, immune cell infiltrates, fragmented and disorganized elastin fibers and collagen deposits that were, for approximately one-fifth of the mice, associated with altered pulmonary function leading to respiratory failure. These lung abnormalities start early in life, as demonstrated in one-quarter of 2-day-old Muc5b-deficient pups. Thus, the mouse mucin Muc5b is essential for maintaining normal lung function.

Paracrine signalling during ZEB1-mediated epithelial-mesenchymal transition augments local myofibroblast differentiation in lung fibrosis

The contribution of epithelial-mesenchymal transition (EMT) to human lung fibrogenesis is controversial. Here we provide evidence that ZEB1-mediated EMT in human alveolar epithelial type II (ATII) cells contributes to the development of lung fibrosis by paracrine signalling to underlying fibroblasts. Activation of EGFR-RAS-ERK signalling in ATII cells induced EMT via ZEB1. ATII cells had extremely low extracellular matrix gene expression even after induction of EMT, however conditioned media from ATII cells undergoing RAS-induced EMT augmented TGFβ-induced profibrogenic responses in lung fibroblasts. This epithelial-mesenchymal crosstalk was controlled by ZEB1 via the expression of tissue plasminogen activator (tPA). In human fibrotic lung tissue, nuclear ZEB1 expression was detected in alveolar epithelium adjacent to sites of extracellular matrix (ECM) deposition, suggesting that ZEB1-mediated paracrine signalling has the potential to contribute to early fibrotic changes in the lung interstitium. Targeting this novel ZEB1 regulatory axis may be a viable strategy for the treatment of pulmonary fibrosis.

The role of HIF-1α-VEGF pathway in bronchiolitis obliterans after lung transplantation

Background

Graft function may be affected if the organ is exposed to hypoxia. We hypothesized that bronchiolitis obliterans (BO) after lung transplantation is associated with hypoxia-inducible factor-1α (HIF-1α). This study compares the expression of HIF-1α and its downstream proteins in allograft and isograft to explore the relationship between this pathway and BO in rats.

Material and methods

We performed an orthotopic left pulmonary transplant model using the tri-cuff vascular anastomosis method and evaluated the histopathology, including the severity of fibrosis (SF). The expression of HIF-1α, VEGF-A, and VEGFR-2 was accessed by immunohistochemistry.

Results

The imageology and pathology showed that the allogenic model developed BO 90 days after the operation. The percentages of a high expression of HIF-1α, VEGF-A, and VEGFR-2 in the allogeneic group were 77.27, 63.64, and 68.18% higher than in the isogeneic group, respectively. The SF score was highest in the allograft and was positively correlated with the expression of the proteins.

Conclusion

This model can simulate human BO after lung transplantation. The expression of HIF-1α and its downstream proteins in post-transplantation was up-regulated, suggesting that activation of the HIF-1α-VEGF pathway might be involved in the occurrence and prognosis of BO.

Role of Epidermal Growth Factor Receptor (EGFR) and Its Ligands in Kidney Inflammation and Damage

Chronic kidney disease (CKD) is characterized by persistent inflammation and progressive fibrosis, ultimately leading to end-stage renal disease. Although many studies have investigated the factors involved in the progressive deterioration of renal function, current therapeutic strategies only delay disease progression, leaving an unmet need for effective therapeutic interventions that target the cause behind the inflammatory process and could slow down or reverse the development and progression of CKD. Epidermal growth factor receptor (EGFR) (ERBB1), a membrane tyrosine kinase receptor expressed in the kidney, is activated after renal damage, and preclinical studies have evidenced its potential as a therapeutic target in CKD therapy. To date, seven official EGFR ligands have been described, including epidermal growth factor (EGF) (canonical ligand), transforming growth factor-α, heparin-binding epidermal growth factor, amphiregulin, betacellulin, epiregulin, and epigen. Recently, the connective tissue growth factor (CTGF/CCN2) has been described as a novel EGFR ligand. The direct activation of EGFR by its ligands can exert different cellular responses, depending on the specific ligand, tissue, and pathological condition. Among all EGFR ligands, CTGF/CCN2 is of special relevance in CKD. This growth factor, by binding to EGFR and downstream signaling pathway activation, regulates renal inflammation, cell growth, and fibrosis. EGFR can also be “transactivated” by extracellular stimuli, including several key factors involved in renal disease, such as angiotensin II, transforming growth factor beta (TGFB), and other cytokines, including members of the tumor necrosis factor superfamily, showing another important mechanism involved in renal pathology. The aim of this review is to summarize the contribution of EGFR pathway activation in experimental kidney damage, with special attention to the regulation of the inflammatory response and the role of some EGFR ligands in this process. Better insights in EGFR signaling in renal disease could improve our current knowledge of renal pathology contributing to therapeutic strategies for CKD development and progression.

IL-17A Blockade Attenuates Obliterative Bronchiolitis and IFN-γ Cellular Immune Response in Lung Allografts

Obliterative bronchiolitis (OB), characterized by fibrous obliteration of the small airways, is a major impediment to long-term survival in lung allograft recipients. We found previously that IL-17A is produced primarily by CD4⁺ T cells and γδ T cells after lung transplant in a mouse model of orthotopic lung transplant. The absence of either subset of T cells was compensated for by expansion of the other subset, which suggested that systemic blockade of IL-17A was necessary. To determine the specific role of IL-17A in the development of OB, we treated lung allograft recipients with an IL-17A antagonistic antibody. After IL-17A blockade, the incidence of OB was significantly reduced in lung allografts. IL-17A blockade also significantly attenuated the severity of acute rejection and overall lung fibrosis. The decreased OB incidence was associated with reduced lymphocyte recruitment, particularly CD8⁺ T cells and other IFN-γ-producing lymphocytes, to the lung allograft. Interestingly, IL-17A blockade led to an increase in the frequency of IL-17A-producing T-helper cell type 17 cells and γδ T cells in lung allografts, suggesting that IL-17A is a negative regulator of these T cells. Our data suggest that blocking IL-17A after lung transplant reduces the overall IFN-γ-mediated lymphocyte response and decreases the development of OB.

Overactive Epidermal Growth Factor Receptor Signaling Leads to Increased Fibrosis after Severe Acute Respiratory Syndrome Coronavirus Infection

Severe acute respiratory syndrome coronavirus (SARS-CoV) is a highly pathogenic respiratory virus that causes morbidity and mortality in humans. After infection with SARS-CoV, the acute lung injury caused by the virus must be repaired to regain lung function. A dysregulation in this wound healing process leads to fibrosis. Many survivors of SARS-CoV infection develop pulmonary fibrosis (PF), with higher prevalence in older patients. Using mouse models of SARS-CoV pathogenesis, we have identified that the wound repair pathway, controlled by the epidermal growth factor receptor (EGFR), is critical to recovery from SARS-CoV-induced tissue damage. In mice with constitutively active EGFR [EGFR(DSK5) mice], we find that SARS-CoV infection causes enhanced lung disease. Importantly, we show that during infection, the EGFR ligands amphiregulin and heparin-binding EGF-like growth factor (HB-EGF) are upregulated, and exogenous addition of these ligands during infection leads to enhanced lung disease and altered wound healing dynamics. Our data demonstrate a key role of EGFR in the host response to SARS-CoV and how it may be implicated in lung disease induced by other highly pathogenic respiratory viruses.IMPORTANCE PF has many causative triggers, including severe respiratory viruses such as SARS-CoV. Currently there are no treatments to prevent the onset or limit the progression of PF, and the molecular pathways underlying the development of PF are not well understood. In this study, we identified a role for the balanced control of EGFR signaling as a key factor in progression to PF. These data demonstrate that therapeutic treatment modulating EGFR activation could protect against PF development caused by severe respiratory virus infection.

The role of epidermal growth factor receptor (EGFR) signaling in SARS coronavirus-induced pulmonary fibrosis

Many survivors of the 2003 outbreak of severe acute respiratory syndrome (SARS) developed residual pulmonary fibrosis with increased severity seen in older patients. Autopsies of patients that died from SARS also showed fibrosis to varying extents. Pulmonary fibrosis can be occasionally seen as a consequence to several respiratory viral infections but is much more common after a SARS coronavirus (SARS-CoV) infection. Given the threat of future outbreaks of severe coronavirus disease, including Middle East respiratory syndrome (MERS), it is important to understand the mechanisms responsible for pulmonary fibrosis, so as to support the development of therapeutic countermeasures and mitigate sequelae of infection. In this article, we summarize pulmonary fibrotic changes observed after a SARS-CoV infection, discuss the extent to which other respiratory viruses induce fibrosis, describe available animal models to study the development of SARS-CoV induced fibrosis and review evidence that pulmonary fibrosis is caused by a hyperactive host response to lung injury mediated by epidermal growth factor receptor (EGFR) signaling. We summarize work from our group and others indicating that inhibiting EGFR signaling may prevent an excessive fibrotic response to SARS-CoV and other respiratory viral infections and propose directions for future research.

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Patients who survived SARS coronavirus infection often developed pulmonary fibrosis.

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Mouse models of SARS-CoV infection recapitulate fibrotic lesions seen in humans.

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Epidermal growth factor receptor (EGFR) may modulate the wound healing response to SARS-CoV.

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The EGFR pathway is a prime target for therapeutic interventions to reduce fibrosis after respiratory virus infection.

Erlotinib Induced Fatal Interstitial Lung Disease in a Patient with Metastatic Non-Small Cell Lung Cancer: Case Report and Review of Literature

Erlotinib is one of the most widely used tyrosine kinase inhibitor targeting human epidermal growth factor receptor. Since its introduction, it has revolutionized the treatment of advanced non-small cell lung cancer. Skin rashes and diarrhea are the most often reported side effects of erlotinib however it is also associated with interstitial pneumonitis or interstitial lung disease, which often turns out to be fatal complication of using this medicine. Though reported scarcely in the western world, the association of interstitial lung disease with epidermal growth factor receptor has attracted a lot of attention in the recent times. Various researches working with murine models of bleomycin-induced pulmonary fibrosis have found a pro and con role of the receptor in development of the interstitial lung disease. We present the case of a patient diagnosed with stage IV adenocarcinoma of the lung with metastasis to brain. He was found to be positive for the human epidermal growth factor mutation and was hence started on erlotinib. Within a few weeks of starting the medicine the patient was admitted with diarrhea. During the course of this admission he developed acute shortness of breath diagnosed as interstitial pneumonitis. The purpose of this case report is to review the literature associated with erlotinib induced interstitial pneumonitis and make the practicing oncologists aware of this rare yet fatal complication of erlotinib. Here we will also review literature, pertaining to the role of epidermal growth factor receptor in development of interstitial lung disease.

Epidermal Growth Factor Receptor (EGF-R) in Dupuytren’s Disease

The aim of this paper was to examine participation of the epidermal growth factor receptor (EGF-R) signal pathway in the pathogenesis of Dupuytren’s disease. The study showed changes in the ratio of membrane EGF-R to its intracellular level during the different clinical stages of Dupuytren’s contracture progression. Our observations of a high ratio of surface to intracellular EGF-R in the palmar aponeurosis of patients with second degree of Dupuytren’s disease (Iselin’s classification), which was significantly higher than this ratio in control palmar fascia ( P = 0.022), would suggest that EGF-R has a role in the involutional phase of the disease.

Expression and Function of the Epidermal Growth Factor Receptor in Physiology and Disease

The epidermal growth factor receptor (EGFR) is the prototypical member of a family of membrane-associated intrinsic tyrosine kinase receptors, the ErbB family. EGFR is activated by multiple ligands, including EGF, transforming growth factor (TGF)-α, HB-EGF, betacellulin, amphiregulin, epiregulin, and epigen. EGFR is expressed in multiple organs and plays important roles in proliferation, survival, and differentiation in both development and normal physiology, as well as in pathophysiological conditions. In addition, EGFR transactivation underlies some important biologic consequences in response to many G protein-coupled receptor (GPCR) agonists. Aberrant EGFR activation is a significant factor in development and progression of multiple cancers, which has led to development of mechanism-based therapies with specific receptor antibodies and tyrosine kinase inhibitors. This review highlights the current knowledge about mechanisms and roles of EGFR in physiology and disease.

TGFα expression in myeloid malignancies

Background

Transforming growth factor α (TGFα) is a peptide growth factor known to be expressed in normal haemopoiesis. It is also expressed in a range of epithelial neoplasms but has not been assessed in haemopoietic malignancies. We have performed an immunohistochemical evaluation of TGFα in acute and chronic myeloid malignancies.

Methods

TGFα expression was semiquantitatively assessed in 69 normal bone marrow trephines and 157 cases of myeloid malignancy using an immunohistochemical approach.

Results

Blast cells of myeloid origin in acute myeloid leukaemia (AML), myelodysplasia and accelerated and blast phases of chronic myeloid leukaemia (CML) were TGFα positive. In acute promyelocytic leukaemia the neoplastic cells had significantly weaker TGFα expression than seen in other forms of AML. The blast cells in CML-accelerated and blast phases were positive with similar expression to AML.

Conclusions

TGFα is expressed in neoplastic myeloblasts and could, therefore, be used as blast cell biomarker in diagnostic haematopathology. In addition, TGFα immunohistochemistry may be of use in identifying a therapeutic target.

CD4 T Cells but Not Th17 Cells Are Required for Mouse Lung Transplant Obliterative Bronchiolitis

Lung transplant survival is limited by obliterative bronchiolitis (OB), but the mechanisms of OB development are unknown. Previous studies in a mouse model of orthotopic lung transplantation suggested a requirement for IL-17. We have used this orthotopic mouse model to investigate the source of IL-17A and the requirement for T cells producing IL-17A. The major sources of IL-17A were CD4(+) T cells and γδ T cells. Depletion of CD4(+) T cells led to a significantly decreased frequency and number of IL-17A(+) lymphocytes and was sufficient to prevent acute rejection and OB. However, mice with STAT3-deficient T cells, which are unable to differentiate into Th17 cells, rejected lung allografts and developed OB similar to control mice. The frequency of IL-17A(+) cells was not decreased in mice with STAT3-deficient T cells due mainly to the presence of IL-17A(+) γδ T cells. Deficiency of γδ T cells also did not affect the development of airway fibrosis. Our data suggest that CD4(+) T cells are required for OB development and expansion of IL-17A responses in the lung, while Th17 and γδ T cells are not absolutely required and may compensate for each other.

ADAM-family metalloproteinases in lung inflammation: potential therapeutic targets

Acute and chronic lung inflammation is driven and controlled by several endogenous mediators that undergo proteolytic conversion from surface-expressed proteins to soluble variants by a disintegrin and metalloproteinase (ADAM)-family members. TNF and epidermal growth factor receptor ligands are just some of the many substrates by which these proteases regulate inflammatory or regenerative processes in the lung. ADAM10 and ADAM17 are the most prominent members of this protease family. They are constitutively expressed in most lung cells and, as recent research has shown, are the pivotal shedding enzymes mediating acute lung inflammation in a cell-specific manner. ADAM17 promotes endothelial and epithelial permeability, transendothelial leukocyte migration, and inflammatory mediator production by smooth muscle and epithelial cells. ADAM10 is critical for leukocyte migration and alveolar leukocyte recruitment. ADAM10 also promotes allergic asthma by driving B cell responses. Additionally, ADAM10 acts as a receptor for Staphylococcus aureus (S. aureus) α-toxin and is crucial for bacterial virulence. ADAM8, ADAM9, ADAM15, and ADAM33 are upregulated during acute or chronic lung inflammation, and recent functional or genetic analyses have linked them to disease development. Pharmacological inhibitors that allow us to locally or systemically target and differentiate ADAM-family members in the lung suppress acute and asthmatic inflammatory responses and S. aureus virulence. These promising results encourage further research to develop therapeutic strategies based on selected ADAMs. These studies need also to address the role of the ADAMs in repair and regeneration in the lung to identify further therapeutic opportunities and possible side effects.

Neutrophil gelatinase-associated lipocalin (NGAL) and insulin-like growth factor (IGF)-1 association with a Mannheimia haemolytica infection in sheep

This study was aimed at mapping the tissue distribution of some inflammatory parameters associated with a Mannheimia haemolytica (M. haemolytica) infection in sheep. The M. haemolytica was isolated and characterized from the affected lungs of slaughtered animals. Cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-10, insulin-like growth factor (IGF)-1, as well as the acute-phase protein, neutrophil gelatinase-associated lipocalin (NGAL), were identified in the lung tissues, the serum, and the lymph nodes of M. haemolytica infected sheep, by enzyme-linked immunosorbent assay (ELISA). NGAL and IGF-1 pointed to an innate immune response, and epithelial cell repairing, respectively. The adaptive immune response was identified through the type of cytokines present in the affected sheep, as TNF-α represents the pro-inflammatory cytokines, and IL-10 represents the anti-inflammatory cytokines. M. haemolytica isolates were confirmed by polymerase chain reaction (PCR) and DNA sequences. There was a significant difference in the concentrations of NGAL, IGF-1, TNF-α, and IL-10, as observed in the affected sheep when compared to the healthy sheep. This study, for the first time, closely describes the distribution of some key and new inflammatory parameters in the tissue homogenate of affected lungs.

Transforming growth factor alpha is a critical mediator of radiation lung injury

Radiation fibrosis of the lung is a late toxicity of thoracic irradiation. Epidermal growth factor (EGF) signaling has previously been implicated in radiation lung injury. We hypothesized that TGF-α, an EGF receptor ligand, plays a key role in radiation-induced fibrosis in lung. Mice deficient in transforming growth factor (TGF-α(-/-)) and control C57Bl/6J (C57-WT) mice were exposed to thoracic irradiation in 5 daily fractions of 6 Gy. Cohorts of mice were followed for survival (n ≥ 5 per group) and tissue collection (n = 3 per strain and time point). Collagen accumulation in irradiated lungs was assessed by Masson's trichrome staining and analysis of hydroxyproline content. Cytokine levels in lung tissue were assessed with ELISA. The effects of TGF-α on pneumocyte and fibroblast proliferation and collagen production were analyzed in vitro. Lysyl oxidase (LOX) expression and activity were measured in vitro and in vivo. Irradiated C57-WT mice had a median survival of 24.4 weeks compared to 48.2 weeks for irradiated TGF-α(-/-) mice (P = 0.001). At 20 weeks after irradiation, hydroxyproline content was markedly increased in C57-WT mice exposed to radiation compared to TGF-α(-/-) mice exposed to radiation or unirradiated C57-WT mice (63.0, 30.5 and 37.6 μg/lung, respectively, P = 0.01). C57-WT mice exposed to radiation had dense foci of subpleural fibrosis at 20 weeks after exposure, whereas the lungs of irradiated TGF-α (-/-) mice were largely devoid of fibrotic foci. Lung tissue concentrations of IL-1β, IL-4, TNF-α, TGF-β and EGF at multiple time points after irradiation were similar in C57-WT and TGF-α(-/-) mice. TGF-α in lung tissue of C57-WT mice rose rapidly after irradiation and remained elevated through 20 weeks. TGF-α(-/-) mice had lower basal LOX expression than C57-WT mice. Both LOX expression and LOX activity were increased after irradiation in all mice but to a lesser degree in TGF-α(-/-) mice. Treatment of NIH-3T3 fibroblasts with TGF-α resulted in increases in proliferation, collagen production and LOX activity. These studies identify TGF-α as a critical mediator of radiation-induced lung injury and a novel therapeutic target in this setting. Further, these data implicate TGF-α as a mediator of collagen maturation through a TGF-β independent activation of lysyl oxidase.

Epidermal growth factor receptor (EGFR) pathway genes and interstitial lung disease: an association study

The etiology and pathogenesis of idiopathic interstitial lung disease (ILD) remain incompletely understood. Genetic susceptibility to ILD has been demonstrated in previous studies. It is well known that EGFR inhibitors can induce ILD in human lung cancer patient with ethnic differences, which prompted us to hypothesize that genetic variation in EGFR pathway genes confer susceptibility to ILD. We aimed in this study to investigate whether functional polymorphisms of EGFR and its ligands genes (EGF and TGFA) were associated with ILD. Three EGFR [-216G/T (rs712830), -191A/C (rs712829), 497R > K(A/G) (rs2227983)], one EGF [61A/G, (rs4444903)] and one TGFA (rs3821262C/T) polymorphisms previously demonstrated to alter gene functions were genotyped in 229 sporadic idiopathic ILD patients and 693 normal healthy individuals. Allelic and genotypic association tests between these polymorphisms and ILD were performed. The EGF 61A/G polymorphism was significantly associated with elevated risk of ILD, with the frequency of G allele significantly increased in the ILD patient population (OR = 1.33, 95%CI = 1.07-1.66, P = 0.0099). None of the other polymorphisms were associated with risk of ILD. Our study suggested that the EGF 61A/G polymorphism may be associated with sporadic ILD. While a false positive finding cannot be excluded, independent studies are warranted to further validate this result.

Generation and activity of a humanized monoclonal antibody that selectively neutralizes the epidermal growth factor receptor ligands transforming growth factor-α and epiregulin

At least seven distinct epidermal growth factor (EGF) ligands bind to and activate the EGF receptor (EGFR). This activation plays an important role in the embryo and in the maintenance of adult tissues. Importantly, pharmacologic EGFR inhibition also plays a critical role in the pathophysiology of diverse disease states, especially cancer. The roles of specific EGFR ligands are poorly defined in these disease states. Accumulating evidence suggests a role for transforming growth factor α (TGFα) in skin, lung, and kidney disease. To explore the role of Tgfa, we generated a monoclonal antibody (mAb41) that binds to and neutralizes human Tgfa with high affinity (KD = 36.5 pM). The antibody also binds human epiregulin (Ereg) (KD = 346.6 pM) and inhibits ligand induced myofibroblast cell proliferation (IC50 values of 0.52 and 1.12 nM for human Tgfa and Ereg, respectively). In vivo, a single administration of the antibody to pregnant mice (30 mg/kg s.c. at day 14 after plug) or weekly administration to neonate mice (20 mg/kg s.c. for 4 weeks) phenocopy Tgfa knockout mice with curly whiskers, stunted growth, and expansion of the hypertrophic zone of growth plate cartilage. Humanization of this monoclonal antibody to a human IgG4 antibody (LY3016859) enables clinical development. Importantly, administration of the humanized antibody to cynomolgus monkeys is absent of the skin toxicity observed with current EGFR inhibitors used clinically and no other pathologies were noted, indicating that neutralization of Tgfa could provide a relatively safe profile as it advances in clinical development.

Inhibition of the αvβ6 integrin leads to limited alteration of TGF-α-induced pulmonary fibrosis

A number of growth factors and signaling pathways regulate matrix deposition and fibroblast proliferation in the lung. The epidermal growth factor receptor (EGFR) family of receptors and the transforming growth factor-β (TGF-β) family are active in diverse biological processes and are central mediators in the initiation and maintenance of fibrosis in many diseases. Transforming growth factor-α (TGF-α) is a ligand for the EGFR, and doxycycline (Dox)-inducible transgenic mice conditionally expressing TGF-α specifically in the lung epithelium develop progressive fibrosis accompanied with cachexia, changes in lung mechanics, and marked pleural thickening. Although recent studies demonstrate that EGFR activation modulates the fibroproliferative effects involved in the pathogenesis of TGF-β induced pulmonary fibrosis, in converse, the direct role of EGFR induction of the TGF-β pathway in the lung is unknown. The αvβ6 integrin is an important in vivo activator of TGF-β activation in the lung. Immunohistochemical analysis of αvβ6 protein expression and bronchoalveolar analysis of TGF-β pathway signaling indicates activation of the αvβ6/TGF-β pathway only at later time points after lung fibrosis was already established in the TGF-α model. To determine the contribution of the αvβ6/TGF-β pathway on the progression of established fibrotic disease, TGF-α transgenic mice were administered Dox for 4 wk, which leads to extensive fibrosis; these mice were then treated with a function-blocking anti-αvβ6 antibody with continued administration of Dox for an additional 4 wk. Compared with TGF-α transgenic mice treated with control antibody, αvβ6 inhibition significantly attenuated pleural thickening and altered the decline in lung mechanics. To test the effects of genetic loss of the β6 integrin, TGF-α transgenic mice were mated with β6-null mice and the degree of fibrosis was compared in adult mice following 8 wk of Dox administration. Genetic ablation of the β6 integrin attenuated histological and physiological changes in the lungs of TGF-α transgenic mice although a significant degree of fibrosis still developed. In summary, inhibition of the β6 integrin led to a modest, albeit significant, effect on pleural thickening and lung function decline observed with TGF-α-induced pulmonary fibrosis. These data support activation of the αvβ6/TGF-β pathway as a secondary effect contributing to TGF-α-induced pleural fibrosis and suggest a complex contribution of multiple mediators to the maintenance of progressive fibrosis in the lung.

Targeting EGFR signalling in chronic lung disease: therapeutic challenges and opportunities

Chronic respiratory diseases, including pulmonary fibrosis, chronic obstructive pulmonary disease (COPD) and lung cancer, are the second leading cause of death among Europeans. Despite this, there have been only a few therapeutic advances in these conditions over the past 20 years. In this review we provide evidence that targeting the epidermal growth factor receptor (EGFR) signalling pathway may represent a novel therapeutic panacea for treating chronic lung disease. Using evidence from human patient samples, transgenic animal models, and cell and molecular biology studies we highlight the roles of this signalling pathway in lung development, homeostasis, repair, and disease ontogeny. We identify mechanisms underlying lung EGFR pathway regulation and suggest how targeting these mechanisms using new and existing therapies has the potential to improve future lung cancer, COPD and pulmonary fibrosis patient outcomes.

Amphiregulin, an epidermal growth factor receptor ligand, plays an essential role in the pathogenesis of transforming growth factor-β-induced pulmonary fibrosis

Dysregulated amphiregulin (AR) expression and EGR receptor (EGFR) activation have been described in animal models of pulmonary fibrosis and in patients with idiopathic pulmonary fibrosis. However, the exact role of AR in the pathogenesis of pulmonary fibrosis has not been clearly defined. Here, we show that a potent profibrogenic cytokine TGF-β1 significantly induced the expression of AR in lung fibroblasts in vitro and in murine lungs in vivo. AR stimulated NIH3T3 fibroblast cell proliferation in a dose-dependent manner. Silencing of AR expression by siRNA or chemical inhibition of EGFR signaling, utilizing AG1478 and gefitinib, significantly reduced the ability of TGF-β1 to stimulate fibroblast proliferation and expression of α-smooth muscle actin, collagen, and other extracellular matrix-associated genes. TGF-β1-stimulated activation of Akt, ERK, and Smad signaling was also significantly inhibited by these interventions. Consistent with these in vitro findings, AR expression was impressively increased in the lungs of TGF-β1 transgenic mice, and either siRNA silencing of AR or chemical inhibition of EGFR signaling significantly reduced TGF-β1-stimulated collagen accumulation in the lung. These studies showed a novel regulatory role for AR in the pathogenesis of TGF-β1-induced pulmonary fibrosis. In addition, these studies suggest that AR, or AR-activated EGFR signaling, is a potential therapeutic target for idiopathic pulmonary fibrosis associated with TGF-β1 activation.

Genetically manipulated mouse models of lung disease: potential and pitfalls

Gene targeting in mice (transgenic and knockout) has provided investigators with an unparalleled armamentarium in recent decades to dissect the cellular and molecular basis of critical pathophysiological states. Fruitful information has been derived from studies using these genetically engineered mice with significant impact on our understanding, not only of specific biological processes spanning cell proliferation to cell death, but also of critical molecular events involved in the pathogenesis of human disease. This review will focus on the use of gene-targeted mice to study various models of lung disease including airways diseases such as asthma and chronic obstructive pulmonary disease, and parenchymal lung diseases including idiopathic pulmonary fibrosis, pulmonary hypertension, pneumonia, and acute lung injury. We will attempt to review the current technological approaches of generating gene-targeted mice and the enormous dataset derived from these studies, providing a template for lung investigators.

Animal models for the study of liver fibrosis: new insights from knockout mouse models

Fibrosis arises as part of a would-healing response that maintains organ structure and integrity following tissue damage but also contributes to a variety of human pathologies such as liver fibrosis. Liver fibrosis is an abnormal response of the liver to persistent injury with the excessive accumulation of collagenous extracellular matrices. Currently there is no effective treatment, and many patients end up with a progressive form of the disease, eventually requiring a liver transplant. The clarification of mechanisms underlying pathogenesis of liver fibrosis and the development of effective therapy are of clinical importance. Experimental animal models, in particular targeted gene knockouts (loss of function) in mice, have become a powerful resource to address the molecular mechanisms or significance of the targeted gene in hepatic functions and diseases. This review will focus on the recent advances in knowledge obtained from genetically engineered mice that provide novel insights into the pathophysiology of liver fibrosis.

Mesenchymal cell survival in airway and interstitial pulmonary fibrosis

Fibrotic reactions in the airways of the lung or the pulmonary interstitium are a common pathologic outcome after exposure to a wide variety of toxic agents, including metals, particles or fibers. The survival of mesenchymal cells (fibroblasts and myofibroblasts) is a key factor in determining whether a fibroproliferative response that occurs after toxic injury to the lung will ultimately resolve or progress to a pathologic state. Several polypeptide growth factors, including members of the platelet-derived growth factor (PDGF) family and the epidermal growth factor (EGF) family, are prosurvival factors that stimulate a replicative and migratory mesenchymal cell phenotype during the early stages of lung fibrogenesis. This replicative phenotype can progress to a matrix synthetic phenotype in the presence of transforming growth factor-β1 (TGF-β1). The resolution of a fibrotic response requires growth arrest and apoptosis of mesenchymal cells, whereas progressive chronic fibrosis has been associated with mesenchymal cell resistance to apoptosis. Mesenchymal cell survival or apoptosis is further influenced by cytokines secreted during Th1 inflammation (e.g., IFN-γ) or Th2 inflammation (e.g., IL-13) that modulate the expression of growth factor activity through the STAT family of transcription factors. Understanding the mechanisms that regulate the survival or death of mesenchymal cells is central to ultimately developing therapeutic strategies for lung fibrosis.

Arylhydrocarbon receptor activation in NCI-H441 cells and C57BL/6 mice: possible mechanisms for lung dysfunction

The arylhydrocarbon receptor (AhR) is known for its ability to bind aromatic-containing compounds, which starts a molecular cascade involving the induction of cytochrome P450s and inflammatory cytokines. Our hypothesis is that many inhaled environmental toxicant components activate these inflammatory pathways via an initial binding to the AhR. To test this possibility, we treated Clara cell-derived NCI-H441 cells with the AhR agonist, 2,3,7,8-tetrachlordibenzo-p-dioxin (TCDD), and demonstrated that AhR activation increased the expression of both cytochrome P450 s and inflammatory markers. We also found increased mucin 5AC production with TCDD treatment. Similar results were observed in NCI-H441 cells treated with urban dust particles. Mucin 5AC expression was highly correlated with increased-expression cyclooxygenase-2 and IL-1beta, thus implicating these two inflammatory markers as possible conduits for AhR-mediated mucin production. We hypothesize that this increase in mucin 5AC production is a result of inflammation-induced differentiation of our epithelial cell to a mucin-producing cell. This theory is supported by morphological changes observed in the cells, as well as decreased expression of Clara cell secretory protein (CC10). In an in vivo C57BL/6 mouse model, TCDD increased expression of inflammatory cytokines, mucin 5AC, and a number of matrix metalloproteases in whole-lung samples. These changes were not seen in mice in which AhR signaling was repressed. These markers from the whole-lung samples have been correlated to onset of bronchitis, asthma, small airways disease, and fibrosis, and their increased expression further implicates AhR activation in producing the molecular environment for the development of lung injury to occur.

Rapamycin prevents transforming growth factor-alpha-induced pulmonary fibrosis

Transforming growth factor (TGF)-alpha is a ligand for the epidermal growth factor receptor (EGFR). EGFR activation is associated with fibroproliferative processes in human lung disease and animal models of pulmonary fibrosis. Overexpression of TGF-alpha in transgenic mice causes progressive and severe pulmonary fibrosis; however, the intracellular signaling pathways downstream of EGFR mediating this response are unknown. Using a doxycycline-regulatable transgenic mouse model of lung-specific TGF-alpha expression, we observed increased PCNA protein and phosphorylation of Akt and p70S6K in whole lung homogenates in association with induction of TGF-alpha. Induction in the lung of TGF-alpha caused progressive pulmonary fibrosis over a 7-week period. Daily administration of rapamycin prevented accumulation of total lung collagen, weight loss, and changes in pulmonary mechanics. Treatment of mice with rapamycin 4 weeks after the induction of TGF-alpha prevented additional weight loss, increases in total collagen, and changes in pulmonary mechanics. Rapamycin prevented further increases in established pulmonary fibrosis induced by EGFR activation. This study demonstrates that mammalian target of rapamycin (mTOR) is a major effector of EGFR-induced pulmonary fibrosis, providing support for further studies to determine the role of mTOR in the pathogenesis and treatment of pulmonary fibrosis.

Early growth response-1 suppresses epidermal growth factor receptor-mediated airway hyperresponsiveness and lung remodeling in mice

Transforming growth factor (TGF)-alpha and its receptor, the epidermal growth factor receptor, are induced after lung injury and are associated with remodeling in chronic pulmonary diseases, such as pulmonary fibrosis and asthma. Expression of TGF-alpha in the lungs of adult mice causes fibrosis, pleural thickening, and pulmonary hypertension, in addition to increased expression of a transcription factor, early growth response-1 (Egr-1). Egr-1 was increased in airway smooth muscle (ASM) and the vascular adventitia in the lungs of mice conditionally expressing TGF-alpha in airway epithelium (Clara cell secretory protein-rtTA(+/-)/[tetO](7)-TGF-alpha(+/-)). The goal of this study was to determine the role of Egr-1 in TGF-alpha-induced lung disease. To accomplish this, TGF-alpha-transgenic mice were crossed to Egr-1 knockout (Egr-1(ko/ko)) mice. The lack of Egr-1 markedly increased the severity of TGF-alpha-induced pulmonary disease, dramatically enhancing airway muscularization, increasing pulmonary fibrosis, and causing greater airway hyperresponsiveness to methacholine. Smooth muscle hyperplasia, not hypertrophy, caused the ASM thickening in the absence of Egr-1. No detectable increases in pulmonary inflammation were found. In addition to the airway remodeling disease, vascular remodeling and pulmonary hypertension were also more severe in Egr-1(ko/ko) mice. Thus, Egr-1 acts to suppress epidermal growth factor receptor-mediated airway and vascular muscularization, fibrosis, and airway hyperresponsiveness in the absence of inflammation. This provides a unique model to study the processes causing pulmonary fibrosis and ASM thickening without the complicating effects of inflammation.

Epithelial cell alpha3beta1 integrin links beta-catenin and Smad signaling to promote myofibroblast formation and pulmonary fibrosis

Pulmonary fibrosis, in particular idiopathic pulmonary fibrosis (IPF), results from aberrant wound healing and scarification. One population of fibroblasts involved in the fibrotic process is thought to originate from lung epithelial cells via epithelial-mesenchymal transition (EMT). Indeed, alveolar epithelial cells (AECs) undergo EMT in vivo during experimental fibrosis and ex vivo in response to TGF-beta1. As the ECM critically regulates AEC responses to TGF-beta1, we explored the role of the prominent epithelial integrin alpha3beta1 in experimental fibrosis by generating mice with lung epithelial cell-specific loss of alpha3 integrin expression. These mice had a normal acute response to bleomycin injury, but they exhibited markedly decreased accumulation of lung myofibroblasts and type I collagen and did not progress to fibrosis. Signaling through beta-catenin has been implicated in EMT; we found that in primary AECs, alpha3 integrin was required for beta-catenin phosphorylation at tyrosine residue 654 (Y654), formation of the pY654-beta-catenin/pSmad2 complex, and initiation of EMT, both in vitro and in vivo during the fibrotic phase following bleomycin injury. Finally, analysis of lung tissue from IPF patients revealed the presence of pY654-beta-catenin/pSmad2 complexes and showed accumulation of pY654-beta-catenin in myofibroblasts. These findings demonstrate epithelial integrin-dependent profibrotic crosstalk between beta-catenin and Smad signaling and support the hypothesis that EMT is an important contributor to pathologic fibrosis.

The epidermal growth factor receptor ligand amphiregulin participates in the development of mouse liver fibrosis

The hepatic wound-healing response to chronic noxious stimuli may lead to liver fibrosis, a condition characterized by excessive deposition of extracellular matrix. Fibrogenic cells, including hepatic stellate cells and myofibroblasts, are activated in response to a variety of cytokines, growth factors, and inflammatory mediators. The involvement of members of the epidermal growth factor family in this process has been suggested. Amphiregulin (AR) is an epidermal growth factor receptor (EGFR) ligand specifically induced upon liver injury. Here, we have addressed the in vivo role of AR in experimental liver fibrosis. To this end, liver fibrosis was induced in AR+/+ and AR-/- mice by chronic CCl(4) administration. Histological and molecular markers of hepatic fibrogenesis were measured. Additionally, the response of cultured human and mouse liver fibrogenic cells to AR was evaluated. We observed that AR was expressed in isolated Kupffer cells and liver fibrogenic cells in response to inflamatory stimuli and platelet-derived growth factor, respectively. We demonstrate that the expression of alpha-smooth muscle actin and collagen deposition were markedly reduced in AR-/- mice compared to AR+/+ animals. AR-/- mice also showed reduced expression of tissue inhibitor of metalloproteinases-1 and connective tissue growth factor, two genes that responded to AR treatment in cultured fibrogenic cells. AR also stimulated cell proliferation and exerted a potent antiapoptotic effect on isolated fibrogenic cells.

CONCLUSION

These results indicate that among the different EGFR ligands, AR plays a specific role in liver fibrosis. AR may contribute to the expression of fibrogenic mediators, as well as to the growth and survival of fibrogenic cells. Additionally, our data lend further support to the role of the EGFR system in hepatic fibrogenesis.

Identification of early molecular pathways affected by paraquat in rat lung

We have used global gene expression profiling, combined with pathway analysis tools, to identify in rats the molecular events associated with paraquat toxicity in the lung. Early (2, 8 and 18h) gene expression changes induced following intraperitoneal (i.p.) exposure to paraquat were measured in the caudal lobe of lungs using Affymetrix rat genome GeneChips (31,042 probe sets). A single high dose of paraquat dichloride (20mg/kg) was used that has been shown previously to cause in rats extensive lung fibrosis after 10 days. Hierarchical clustering of 543 paraquat-responsive genes (false discovery rate<0.05) revealed that under these conditions of exposure paraquat induces a staged transcriptional response in the rat lung that precedes the appearance of lung damage. We report here that many of the transcriptional responses to paraquat were rapid (being maximal at 2h post-dose), and that the predominant molecular functions and biological processes associated with these genes include membrane transport, oxidative stress, lung development, epithelial cell differentiation and transforming growth factor beta (TGF-beta) signalling. These data provide novel insights into the molecular pathways that lead to toxicity after exposure of the rat lung to paraquat.

Gefitinib prevents bleomycin-induced lung fibrosis in mice

RATIONALE

Transforming growth factor-alpha and epidermal growth factor (EGF), the ligands for EGF receptor (EGFR), stimulate fibroblast proliferation and play an important role in the pathogenesis of pulmonary fibrosis. Therefore, inhibition of the EGFR signal by an EGFR tyrosine kinase inhibitor (EGFR-TKI) may prevent pulmonary fibrosis. However, there is a possibility that blocking the EGFR signal may inhibit epithelial cell repair, thereby exaggerating lung fibrosis.

OBJECTIVE

To investigate the effect of EGFR-TK inhibition on lung fibrosis.

METHODS

We looked at the effects of the EGFR-TKIs gefitinib (20, 90, 200 mg/kg) and AG1478 (12 mg/kg) on a bleomycin-induced lung fibrosis model in mice.

MEASUREMENTS AND MAIN RESULTS

Gefitinib prevented lung fibrosis at all three doses. Furthermore, in those mice that did not receive bleomycin treatment, gefitinib at 200 mg/kg did not induce lung fibrosis. Immunohistochemistry revealed that phosphorylation of EGFR in lung mesenchymal cells induced by bleomycin was inhibited by gefitinib. AG1478 also attenuated the lung fibrosis. In vitro studies further demonstrated that the addition of gefitinib or AG1478 suppressed the EGFR ligand-induced proliferation of lung fibroblasts.

CONCLUSIONS

These findings suggest that, in the preclinical setting, EGFR-TKIs may have a protective effect on lung fibrosis induced by bleomycin. Because these molecular targeted drugs may have differing effects depending on species and individuals, a cautious interpretation is warranted.

In situ assessment of oxidant and nitrogenic stress in bleomycin pulmonary fibrosis

Reactive oxygen species (ROS) and nitric oxide (NO) have a role in the development of pulmonary fibrosis after bleomycin administration. The ROS production induces an antioxidant response, involving superoxide dismutases (SODs), catalase, and glutathione peroxidases. We compared in situ oxidative burden and antioxidant enzyme activity in bleomycin-injured rat lungs and normal controls. ROS expression and catalase, glucose-6-phosphate-dehydrogenase (G6PHD), and NOS/NADPH-diaphorase activity were investigated by using histochemical reactions. Nitric oxide synthase (e-NOS and i-NOS) and SOD (MnSOD, Cu/ZnSOD, ECSOD) expression was investigated immunohistochemically. After treatment ROS production was enhanced in both phagocytes and in type II alveolar epithelial cells. Mn, Cu/Zn, and ECSOD were overexpressed in parenchymal cells, whereas interstitium expressed ECSOD. Catalase and G6PHD activity was moderately increased in parenchymal and inflammatory cells. NOS/NADPH-d activity and i-NOS expression increased in alveolar and bronchiolar epithelia and in inflammatory cells. It can be suggested that the concomitant activation of antioxidant enzymes is not adequate to scavenge the oxidant burden induced by bleomycin lung damage. Inflammatory cells and also epithelial cells are responsible of ROS and NO production. This oxidative and nitrosative stress may be a substantial trigger in TGF-beta1 overexpression by activated type II pneumocytes, leading to fibrotic lesions.

Tissue inhibitor of metalloproteinase-1 deficiency amplifies acute lung injury in bleomycin-exposed mice

Bleomycin-induced lung injury triggers a profound and durable increase in tissue inhibitor of metalloproteinase (TIMP)-1 expression, suggesting a potential role for this antiproteinase in the regulation of lung inflammation and fibrosis. TIMP-1 protein induction is spatially restricted to areas of lung injury as determined by immunohistochemistry. Using TIMP-1 null mutation mice, we demonstrate that TIMP-1 deficiency amplifies acute lung injury as determined by exaggerated pulmonary neutrophilia, hemorrhage, and vascular permeability compared with wild-type littermates after bleomycin exposure. The augmented pulmonary neutrophilia observed in TIMP-1-deficient animals was not found in similarly treated TIMP-2-deficient mice. Using TIMP-1 bone marrow (BM) chimeric mice, we observed that the TIMP-1-deficient phenotype was abolished in wild-type recipients of TIMP-1-deficient BM but not in TIMP-1-deficient recipients of wild-type BM. Acute lung injury in TIMP-1-deficient mice was accompanied by exaggerated gelatinase-B activity in the alveolar compartment. TIMP-1 deficiency did not alter neutrophil chemotactic factor accumulation in the injured lung nor neutrophil migration in response to chemotactic stimuli in vivo or in vitro. Moreover, TIMP-1 deficiency did not modify collagen accumulation after bleomycin injury. Our results provide direct evidence that TIMP-1 contributes significantly to the regulation of acute lung injury, functioning to limit inflammation and lung permeability.

Transforming growth factor alpha (TGF-alpha) and other targets of tumor necrosis factor-alpha converting enzyme (TACE) in murine polycystic kidney disease

Transforming growth factor-alpha (TGF-alpha) is abnormally expressed in autosomal recessive polycystic kidney disease (ARPKD). Tumor necrosis factor-alpha converting enzyme (TACE), a metalloproteinase, mediates TGF-alpha processing. In this study, we sought to determine whether TGF-alpha was an absolute requirement for renal cystogenesis and whether its absence would modulate disease severity or related growth factors/receptors expression. Bpk heterozygotes were bred with TGF-alpha null mice to produce cystic and noncystic offspring with or without TGF-alpha. Assessments included kidney weight (KW), body weight (BW), blood urea nitrogen (BUN), and kidney and liver immunohistology. Western analysis assessed kidney expression of amphiregulin (AR), epidermal growth factor (EGF), heparin-binding EGF (HB-EGF), and their receptors, EGFR and ErbB4. A PCR-based methodology for genotyping bpk mice was also developed. No significant differences in KW, BW, KW/BW%, or BUN were seen in cystic mice with versus without TGF-alpha. Cystic kidney disease and liver disease histology were similar. AR, EGF, HB-EGF, EGFR, and ErbB4 were abnormally expressed to an equal degree in kidneys of mice with versus without TGF-alpha. Although previous data suggest a critical role of TGF-alpha in murine PKD, these data show that TGF-alpha is not required for renal cyst formation or kidney or liver disease progression. We speculate that the therapeutic effect of WTACE2 could have been due to effects on several TACE targets, including TGF-alpha, AR, and ErbB4, as well as metalloproteinases other than TACE.

Expression of mutant human epidermal receptor 3 attenuates lung fibrosis and improves survival in mice

Neuregulin-1 (NRG-1), binding to the human epidermal growth factor receptor HER2/HER3, plays a role in pulmonary epithelial cell proliferation and recovery from injury in vitro. We hypothesized that activation of HER2/HER3 by NRG-1 would also play a role in recovery from in vivo lung injury. We tested this hypothesis using bleomycin lung injury of transgenic mice incapable of signaling through HER2/HER3 due to lung-specific dominant-negative HER3 (DNHER3) expression. In animals expressing DNHER3, protein leak, cell infiltration, and NRG-1 levels in bronchoalveolar lavage fluid increased after injury, similar to that in nontransgenic littermate control animals. However, HER2/HER3 was not activated, and DNHER3 animals displayed fewer lung morphological changes at 10 and 21 days after injury (P = 0.01). In addition, they contained 51% less collagen in injured lungs (P = 0.04). Transforming growth factor-beta1 did not increase in bronchoalveolar lavage fluid from DNHER3 mice compared with nontransgenic littermate mice (P = 0.001), suggesting that a mechanism for the decreased fibrosis was lack of transforming growth factor-beta1 induction in DNHER3 mice. Severe lung injury (0.08 units bleomycin) resulted in 80% mortality of nontransgenic mice, but only 35% mortality of DNHER3 transgenic mice (P = 0.04). Thus inhibition of HER2/HER3 signaling protects against pulmonary fibrosis and improves survival.

Bronchopulmonary dysplasia in preterm infants: pathophysiology and management strategies

Bronchopulmonary dysplasia (BPD) has classically been described as including inflammation, architectural disruption, fibrosis, and disordered/delayed development of the infant lung. As infants born at progressively earlier gestations have begun to survive the neonatal period, a 'new' BPD, consisting primarily of disordered/delayed development, has emerged. BPD causes not only significant complications in the newborn period, but is associated with continuing mortality, cardiopulmonary dysfunction, re-hospitalization, growth failure, and poor neurodevelopmental outcome after hospital discharge. Four major risk factors for BPD include premature birth, respiratory failure, oxygen supplementation, and mechanical ventilation, although it is unclear whether any of these factors is absolutely necessary for development of the condition. Genetic susceptibility, infection, and patent ductus arteriosus have also been implicated in the pathogenesis of the disease. The strategies with the strongest evidence for effectiveness in preventing or lessening the severity of BPD include prevention of prematurity and closure of a clinically significant patent ductus arteriosus. Some evidence of effectiveness also exists for single-course therapy with antenatal glucocorticoids in women at risk for delivering premature infants, surfactant replacement therapy in intubated infants with respiratory distress syndrome, retinol (vitamin A) therapy, and modes of respiratory support designed to minimize 'volutrauma' and oxygen toxicity. The most effective treatments for ameliorating symptoms or preventing exacerbation in established BPD include oxygen therapy, inhaled glucocorticoid therapy, and vaccination against respiratory pathogens.Many other strategies for the prevention or treatment of BPD have been proposed, but have weaker or conflicting evidence of effectiveness. In addition, many therapies have significant side effects, including the possibility of worsening the disease despite symptom improvement. For instance, supraphysiologic systemic doses of glucocorticoids lessen the incidence of BPD in infants at risk for the disease, and promote weaning of oxygen and mechanical ventilation in infants with established BPD. However, the side effects of systemic glucocorticoid therapy, most notably the recently recognized adverse effects on neurodevelopment, preclude their routine use for the prevention or treatment of BPD. Future research in BPD will most probably focus on continued incremental improvements in outcome, which are likely to be achieved through the combined effects of many therapeutic modalities.

Murine oviduct epithelial cell cytokine responses to Chlamydia muridarum infection include interleukin-12-p70 secretion

Epithelial cells play an important role in host defense as sentinels for invading microbial pathogens. Chlamydia trachomatis is an intracellular bacterial pathogen that replicates in reproductive tract epithelium. Epithelial cells lining the reproductive tract likely play a key role in triggering inflammation and adaptive immunity during Chlamydia infections. For this report a murine oviduct epithelial cell line was derived in order to determine how epithelial cells influence innate and adaptive immune responses during Chlamydia infections. As expected, oviduct epithelial cells infected by Chlamydia muridarum produced a broad spectrum of chemokines, including CXCL16, and regulators of the acute-phase response, including interleukin-1alpha (IL-1alpha), IL-6, and tumor necrosis factor alpha. In addition, infected epithelial cells expressed cytokines that augment gamma interferon (IFN) production, including IFN-alpha/beta and IL-12-p70. To my knowledge this is the first report of a non-myeloid/lymphoid cell type making IL-12-p70 in response to an infection. Equally interesting, infected epithelial cells significantly upregulated transforming growth factor alpha precursor expression, suggesting a mechanism by which they might play a direct role in the pathological scarring seen as a consequence of Chlamydia infections. Data from these in vitro studies predict that infected oviduct epithelium contributes significantly to host innate and adaptive defenses but may also participate in the immunopathology seen with Chlamydia infections.

IL-13 and IL-1beta promote lung fibroblast growth through coordinated up-regulation of PDGF-AA and PDGF-Ralpha

Peribronchiolar fibrosis is a prominent feature of airway remodeling in asthma and involves fibroblast growth and collagen deposition. Interleukin-13 (IL-13), a T-helper 2 cytokine, is a key mediator of airway remodeling in asthma, yet the mechanism through which IL-13 promotes fibroblast growth has not been investigated. In this study, we show that IL-13 stimulates the mitogenesis of mouse, rat, and human lung fibroblasts through release of a soluble mitogen that we identified as PDGF-AA. The IL-13-induced growth of human lung fibroblasts was attenuated by an anti-PDGF-AA neutralizing antibody, and IL-13 stimulated human lung fibroblasts to secrete PDGF-AA. Fibroblasts derived from mouse embryos possessing the lethal Patch mutation, which lack the PDGF-Ralpha, showed no mitogenic response to IL-13. However, Patch cells did exhibit IL-13-induced STAT-6 phosphorylation. Stable transfection of the PDGF-Ralpha into Patch cells restored the growth response to PDGF-AA and IL-13. Through the use of lung fibroblasts from STAT-6-deficient mice, we showed that IL-13-induced PDGF-AA release is STAT-6 dependent, but PDGF-AA-induced growth is STAT-6 independent. Finally, we showed that IL-1beta enhanced IL-13-induced mitogenesis of rat lung fibroblasts through up-regulation of the PDGF-Ralpha. Our findings indicate that IL-13 acts in synergy with IL-1beta to stimulate growth by coordinately up-regulating PDGF-AA and the PDGF-Ralpha, respectively.

Conditional expression of transforming growth factor-alpha in adult mouse lung causes pulmonary fibrosis

To determine whether overexpression of transforming growth factor (TGF)-alpha in the adult lung causes remodeling independently of developmental influences, we generated conditional transgenic mice expressing TGF-alpha in the epithelium under control of the doxycycline (Dox)-regulatable Clara cell secretory protein promoter. Two transgenic lines were generated, and following 4 days of Dox-induction TGF-alpha levels in whole lung homogenate were increased 13- to 18-fold above nontransgenic levels. After TGF-alpha induction, transgenic mice developed progressive pulmonary fibrosis and body weight loss, with mice losing 15% of their weight after 6 wk of TGF-alpha induction. Fibrosis was detected within 4 days of TGF-alpha induction and developed initially in the perivascular, peribronchial, and pleural regions but later extended into the interstitium. Fibrotic regions were composed of increased collagen and cellular proliferation and were adjacent to airway and alveolar epithelial sites of TGF-alpha expression. Fibrosis progressed in the absence of inflammatory cell infiltrates as determined by histology, without changes in bronchiolar alveolar lavage total or differential cell counts and without changes in proinflammatory cytokines TNF-alpha or IL-6. Active TGF-beta in whole lung homogenate was not altered 1 and 4 days after TGF-alpha induction, and immunostaining was not increased in the peribronchial/perivascular areas at all time points. Chronic epithelial expression of TGF-alpha in adult mice caused progressive pulmonary fibrosis associated with increased collagen and extracellular matrix deposition and increased cellular proliferation. Induction of pulmonary fibrosis by TGF-alpha was independent of inflammation or early activation of TGF-beta.

Transforming growth factor-α and oral fibroma: immunohistochemical and in situ hybridization study

PURPOSE

Transforming growth factor-alpha (TGF-alpha) is usually expressed in cell lines derived from sarcomas. It is known as a mitogen for fibroblasts. The aim of this study was to determine whether there were any differences in the expression pattern of TGF-alpha between normal oral mucosa and oral fibroma.

PATIENTS AND METHODS

Fourteen pathologic specimens (6 males and 8 females; 37.2 +/- 23.2 years) and 10 normal oral mucosal specimens (5 females and 5 males; 43.8 +/- 17.7 years) were used for this study. Identification of TGF-alpha was sought by using immunohistochemistry and in situ hybridization.

RESULTS

The samples from normal oral mucosa did not express TGF-alpha. One sample from oral fibroma did not express TGF-alpha (7.1%). Five samples from oral fibroma expressed TGF-alpha sparsely (35.7%). Eight samples showed diffuse expression of TGF-alpha (57.1%). The immunopositive reaction to TGF-alpha in oral fibroma was localized in the basal layer and the fibroblasts that resided beneath the epithelium. This pattern was also shown in the in situ hybridization study as well.

CONCLUSION

TGF-alpha is expressed in oral fibromas. It suggested that TGF-alpha might play a role in fibroblast proliferation in oral fibromas.