Mast cell chymase: an indispensable instrument in the pathological symphony of idiopathic pulmonary fibrosis?

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and fatal lung disease with no known etiology and treatment options. The hallmarks of the histopathology, which is characteristic of usual interstitial pneumonia (UIP) pattern, include interstitial fibrosis, honeycomb changes and fibroblast foci that develop owing to fibroblast proliferation and excessive matrix deposition. Although the complete pathomechanism is not yet understood, several molecular culprits, including transforming growth factor (TGF)-ß, Angiotensin (Ang) II, endothelin (ET)-1, matrix metalloproteinases (MMPs) and cytokines have been identified. IPF is increasingly believed to be an epithelial-driven disease; however, the literature does support an implication of altered immune response and inflammatory processes in the onset or progression of the disease. Mast cells (MCs) are multifunctional tissue resident cells involved in the inflammatory and immune response. An increasing body of evidence suggests a role of MCs and their mediator chymase in the pathology of IPF. With regard to the underlying mechanisms, it is conceivable that MC chymase may function via activation or processing of factors such as proteases, cytokines and growth factors. In this review, we will discuss how MC chymase is linked to and can potentially contribute to the development of IPF. Moreover, the findings from animal model studies will be discussed to highlight the chymase inhibitors as a promising strategy for the treatment of pulmonary fibrosis.

Endotoxin induces proliferation of NSCLC in vitro and in vivo: role of COX-2 and EGFR activation.

Lung cancer is frequently complicated by pulmonary infections which may impair prognosis of this disease. Therefore, we investigated the effect of bacterial lipopolysaccharides (LPS) on tumor proliferation in vitro in the non-small cell lung cancer (NSCLC) cell line A549, ex vivo in a tissue culture model using human NSCLC specimens and in vivo in the A549 adenocarcinoma mouse model. LPS induced a time- and dose-dependent increase in proliferation of A549 cells as quantified by MTS activity and cell counting. In parallel, an increased expression of the proliferation marker Ki-67 and cyclooxygenase (COX)-2 was detected both in A549 cells and in ex vivo human NSCLC tissue. Large amounts of COX-2-derived prostaglandin (PG)E(2) were secreted from LPS-stimulated A549 cells. Pharmacological interventions revealed that the proliferative effect of LPS was dependent on CD14 and Toll-like receptor (TLR)4. Moreover, blocking of the epidermal growth factor receptor (EGFR) also decreased LPS-induced proliferation of A549 cells. Inhibition of COX-2 activity in A549 cells severely attenuated both PGE(2) release and proliferation in response to LPS. Synthesis of PGE(2) was also reduced by inhibiting CD14, TLR4 and EGFR in A549 cells. The proliferative effect of LPS on A549 cells could be reproduced in the A549 adenocarcinoma mouse model with enhancement of tumor growth and Ki-67 expression in implanted tumors. In summary, LPS induces proliferation of NSCLC cells in vitro, ex vivo in human NSCLC specimen and in vivo in a mouse model of NSCLC. Pulmonary infection may thus directly induce tumor progression in NSCLC.

Tyrosine kinase inhibitors with antiangiogenic properties for the treatment of non-small cell lung cancer.

IMPORTANCE OF THE FIELD: The 5-year survival rate in NSCLC remains < 15% in spite of new chemotherapeutic regimens and targeted therapies. Tyrosine kinase inhibitors (TKIs) with antiangiogenic properties show promise as a new therapeutic approach for NSCLC in recent studies. AREAS COVERED IN THIS REVIEW: This article reviews significant preclinical and clinical studies related to TKI therapy. Many drugs that target tyrosine kinases involved in tumor angiogenesis have recently been developed. Results of preclinical experiments and clinical trials for NSCLC are quite promising. However, response rates are low and the duration of therapeutic response is short. Mechanisms of resistance may reduce the efficacy of TKI therapy, and biomarkers of response are needed to select patients who are more likely to benefit from the therapy. Studies in mice have shown that antiangiogenic TKIs may increase metastasis, although no clear clinical evidence supports these results. WHAT THE READER WILL GAIN: An understanding of the mechanisms of action, clinical trial results, biomarkers of response, adverse effects and possible mechanisms of resistance associated with novel TKI therapy in NSCLC. TAKE HOME MESSAGE: More preclinical and clinical research on the efficacy of TKIs in treating NSCLC is needed, but present results offer great hope for patients.

Role of epidermal growth factor inhibition in experimental pulmonary hypertension.

RATIONALE: Epidermal growth factor (EGF) and its receptors play a role in cell proliferation and survival and are implicated in the pathobiology of pulmonary arterial hypertension (PAH). OBJECTIVES: To study the role of EGF inhibition on experimental pulmonary hypertension. METHODS: We investigated (1) the effects of three clinically approved EGF receptor (EGFR) antagonists in vitro on rat pulmonary arterial smooth muscle cell proliferation and in vivo on experimental pulmonary hypertension (PH) induced by monocrotaline injection in rats and by chronic hypoxia in mice, and (2) the expression of EGFR in the lung tissues from experimental and clinical PH. MEASUREMENTS AND MAIN RESULTS: The EGFR inhibitors gefitinib, erlotinib, and lapatinib inhibited the EGF-induced proliferation of pulmonary arterial smooth muscle cells. In rats with established PH, gefitinib and erlotinib significantly reduced right ventricular systolic pressure and right ventricular hypertrophy. In addition, the medial wall thickness and muscularization of pulmonary arteries were improved. In contrast, lapatinib did not provide therapeutic benefit. These EGFR antagonists at their highest tolerable dose did not yield significant improvement in right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary vascular remodeling in mice with chronic hypoxic PH. Moreover, no significant alteration in the EGFR expression was detected in the lung tissues from patients with idiopathic PAH. CONCLUSIONS: The partial therapeutic efficacy of the EGFR antagonists in animal models of pulmonary hypertension and the absence of significant alteration in EGFR expression in the lungs from patients with idiopathic PAH suggest that EGFRs do not represent a promising target for the treatment of pulmonary hypertension.

Targeting cancer with phosphodiesterase inhibitors.

IMPORTANCE OF THE FIELD: For many cancers, there has been a shift from management with traditional, nonspecific cytotoxic chemotherapies to treatment with molecule-specific targeted therapies that are used either alone or in combination with traditional chemotherapy and radiation therapy. Accumulating data suggest that multi-targeted agents may produce greater benefits than those observed with single-targeted therapies, may have acceptable tolerability profiles, and may be active against a broader range of tumour types. Thus, regulation of cyclic nucleotide signalling is properly regarded as a composite of multiple component pathways involved in diverse aspects of tumour cell function. The impairment of cAMP and/or cGMP generation by overexpression of PDE isoforms that has been described in various cancer pathologies, and the effects of PDE inhibitors in tumour models in vitro and in vivo, may offer promising insight into future cancer treatments because of the numerous advantages of PDE inhibitors. AREAS COVERED IN THIS REVIEW: In this review, we focus on the expression and regulation of cyclic nucleotide phosphodiesterases (PDEs) in tumour progression and provide evidence that PDE inhibitors may be effective agents for treating cancer; the review covers literature from the past several years. WHAT THE READER WILL GAIN: PDEs have been studied in a variety of tumours; data have suggested that the levels of PDE activity are elevated and, therefore, the ratio of cGMP to cAMP is affected. In addition, PDE inhibitors may be potential targets for tumour cell growth inhibition and induction of apoptosis. This review explores the prospects of targeting PDEs with therapeutic agents for cancer, as well as the shortcomings of this approach such as dose-limiting side effects, toxicity/efficacy ratio and selectivity towards tumour tissue. In addition, it includes opinions and suggestion for developing PDE inhibition for cancer treatment from initial concept to potential therapeutic application and final relevance in clinical use. TAKE HOME MESSAGE: Impaired cAMP and/or cGMP generation upon overexpression of PDE isoforms has been described in various cancer pathologies. Inhibition of selective PDE isoforms, which raises the levels of intracellular cAMP and/or cGMP, induces apoptosis and cell cycle arrest in a broad spectrum of tumour cells and regulates the tumour microenvironment. Therefore, the development and clinical application of inhibitors specific for individual PDE isoenzymes may selectively restore normal intracellular signalling, providing antitumour therapy with reduced adverse effects.

Expression and activity of phosphodiesterase isoforms during epithelial mesenchymal transition: the role of phosphodiesterase 4.

Epithelial-mesenchymal transition (EMT) has emerged as a critical event in the pathogenesis of organ fibrosis and cancer and is typically induced by the multifunctional cytokine transforming growth factor (TGF)-beta1. The present study was undertaken to evaluate the potential role of phosphodiesterases (PDEs) in TGF-beta1-induced EMT in the human alveolar epithelial type II cell line A549. Stimulation of A549 with TGF-beta1 induced EMT by morphological alterations and by expression changes of the epithelial phenotype markers E-cadherin, cytokeratin-18, zona occludens-1, and the mesenchymal phenotype markers, collagen I, fibronectin, and alpha-smooth muscle actin. Interestingly, TGF-beta1 stimulation caused twofold increase in total cAMP-PDE activity, contributed mostly by PDE4. Furthermore, mRNA and protein expression demonstrated up-regulation of PDE4A and PDE4D isoforms in TGF-beta1-stimulated cells. Most importantly, treatment of TGF-beta1 stimulated epithelial cells with the PDE4-selective inhibitor rolipram or PDE4 small interfering RNA potently inhibited EMT changes in a Smad-independent manner by decreasing reactive oxygen species, p38, and extracellular signal-regulated kinase phosphorylation. In contrast, the ectopic overexpression of PDE4A and/or PDE4D resulted in a significant loss of epithelial marker E-cadherin but did not result in changes of mesenchymal markers. In addition, Rho kinase signaling activated by TGF-beta1 during EMT demonstrated to be a positive regulator of PDE4. Collectively, the findings presented herein suggest that TGF-beta1 mediated up-regulation of PDE4 promotes EMT in alveolar epithelial cells. Thus, targeting PDE4 isoforms may be a novel approach to attenuate EMT-associated lung diseases such as pulmonary fibrosis and lung cancer.

Evaluation of angiogenesis using micro-computed tomography in a xenograft mouse model of lung cancer.

Quantitative evaluation of lung tumor angiogenesis using immunohistochemical techniques has been limited by difficulties in generating reproducible data. To analyze intrapulmonary tumor angiogenesis, we used high-resolution micro-computed tomography (micro-CT) of lung tumors of mice inoculated with mouse Lewis lung carcinoma (LLC1) or human adenocarcinoma (A549) cell lines. The lung vasculature was filled with the radiopaque silicone rubber, Microfil, through the jugular vein (in vivo application) or pulmonary artery (ex vivo application). In addition, human adenocarcinoma lung tumor-bearing mice treated site-specifically with humanized monoclonal antibody (bevacizumab) against vascular endothelial growth factor. Quantitative analysis of lung tumor microvessels imaged with micro-CT showed that more vessels (mainly small, <0.02 mm(2)) were filled using the in vivo (5.4%) compared with the ex vivo (2.1%) method. Furthermore, bevacizumab-treated lung tumor-bearing mice showed significantly reduced lung tumor volume and lung tumor angiogenesis compared with untreated mice as assessed by micro-CT. Interestingly, microvascularization of mainly the smaller vessels (<0.02 mm(2)) was reduced after bevacizumab treatment. This observation with micro-CT was nicely correlated with immunohistochemical measurement of microvessels. Therefore, micro-CT is a novel method for investigating lung tumor angiogenesis, and this might be considered as an additional complementary tool for precise quantification of angiogenesis.

Role of the prostanoid EP4 receptor in iloprost-mediated vasodilatation in pulmonary hypertension.

RATIONALE: Iloprost is effective for the treatment of pulmonary hypertension. It acts through elevation of cAMP by binding to the prostacyclin receptor (IP receptor). However, there is evidence that patients with severe pulmonary hypertension have decreased expression of the IP receptor in the remodeled pulmonary arterial smooth muscle. OBJECTIVES: We hypothesized that prostanoid receptors other than the IP receptor are involved in signal transduction by iloprost. METHODS: Immunoblotting was used to detect the IP and prostanoid EP4 receptor in lung tissue from patients with idiopathic pulmonary arterial hypertension, and immunohistochemistry was used to detect these receptors in lung sections from rats treated with monocrotaline (MCT28d). Protein and mRNA were isolated from pulmonary arterial smooth muscle cells (PASMCs) from control and MCT28d rats treated with AH6809 (an EP2 receptor antagonist) and AH23848 (an EP4 receptor antagonist) in combination with iloprost. Intracellular cAMP was also assessed in these tissues. MEASUREMENTS AND MAIN RESULTS: IP receptor expression was reduced in idiopathic pulmonary arterial hypertension patient lung samples and MCT28d rat lungs compared with the controls. Reverse transcriptase-polymerase chain reaction and immunoblotting of MCT28d rat PASMC extracts revealed scant expression of the IP receptor but stable expression of EP4 receptor, compared with controls. Iloprost-induced elevation in intracellular cAMP in PASMCs was dose-dependently reduced by AH23848, but not by AH6809. CONCLUSIONS: Iloprost mediates vasodilatory functions via the EP4 receptor in the case of low IP receptor expression associated with pulmonary arterial hypertension. This is a previously unrecognized mechanism for iloprost, and illustrates that the EP4 receptor may be a novel therapeutic approach for the treatment of pulmonary arterial hypertension.

A combination hybrid-based vaccination/adoptive cellular therapy to prevent tumor growth by involvement of T cells.

Cancer immunotherapy with dendritic cell-tumor cell fusion hybrids induces polyclonal stimulation against a variety of tumor antigens, including unknown antigens. Hybrid cells can prime CTLs, which subsequently develop antitumor responses. The aim of this study was to enhance the known antitumor effect of hybrid vaccination (HC-Vacc) and hybrid-primed adoptive T-cell therapy (HC-ACT) using the poorly immunogenic Lewis lung carcinoma (LLC1) model. The strategy used was a combination of a double HC-Vacc alternating with HC-ACT (HC-Vacc/ACT). Using flat-panel volumetric computer tomography and immunohistochemistry, we showed a significant retardation of tumor growth (85%). In addition, a significant delay in tumor development, a reduction in the number of pulmonary metastases, and increased survival times were observed. Furthermore, the tumors displayed significant morphologic changes and increased apoptosis, as shown by up-regulation of gene expression of the proapoptotic markers Fas, caspase-8, and caspase-3. The residual tumor masses seen in the HC-Vacc/ACT-treated mice were infiltrated with CD4+ and CD8+ lymphocytes and showed elevated IFNgamma expression. Moreover, splenic enlargement observed in HC-Vacc/ACT-treated mice reflected the increased functionality of T cells, as also indicated by increased expression of markers for CTL activation, differentiation, and proliferation (Cd28, Icosl, Tnfrsf13, and Tnfsf14). Our findings indicate that the combination therapy of dendritic cell-tumor cell HC-Vacc/ACT is a very effective and a promising immunotherapeutic regimen against poorly immunogenic carcinomas.

Pegfilgrastim as hematopoietic support for dose-dense chemoimmunotherapy with R-CHOP-14 as first-line therapy in elderly patients with diffuse large B cell lymphoma.

GOALS OF WORK: Recently, 6 cycles of R-CHOP-14 have been recommended as the reference standard regimen for the treatment of elderly patients with diffuse large B-cell lymphoma (DLBCL). Pegfilgrastim has been shown to facilitate dose-dense chemotherapy schedules with a single administration per chemotherapy cycle. The aims of this study were to evaluate the use of pegfilgrastim in combination with the R-CHOP-14 regimen in a homogenous group of previously untreated elderly patients with DLBCL and to assess the pharmacokinetics of pegfilgrastim within this patient population. MATERIALS AND METHODS: Ten patients with DLBCL between 60 and 80 years of age received a single subcutaneous injection of 6 mg pegfilgrastim 24 h after administration of R-CHOP chemoimmunotherapy, which was repeated for 6 to 8 cycles in two-weekly intervals. A total of 348 blood samples were collected. Pegfilgrastim plasma levels and absolute neutrophil counts were measured every other day during the first treatment cycle and twice weekly during all consecutive cycles. MAIN RESULTS: Sixty-three of 72 cycles (87.5%) could be delivered on time and at the planned dose. Median absolute neutrophil nadir was 0.32 g/l on day 9. Grade 3/4 granulocytopenia occurred in all patients. Febrile neutropenia occurred in two patients. Plasma levels of pegfilgrastim remained elevated during the neutropenic phase. At the start of hematologic recovery, plasma concentrations of pegfilgrastim decreased rapidly to baseline levels. Median pegfilgrastim trough plasma level was 0.43 ng/ml on the day preceding the next application. CONCLUSIONS: A single fixed dose of 6 mg of pegfilgrastim given once per cycle of R-CHOP-14 is effective in supporting neutrophil recovery to allow two-weekly drug administration in previously untreated elderly patients with DLBCL. However, close monitoring for infectious complications is mandatory in this patient population.

Hybrid-primed lymphocytes and hybrid vaccination prevent tumor growth of lewis lung carcinoma in mice.

Dendritic cell (DC)-tumor cell hybrids are currently being evaluated as a novel antitumor vaccination strategy. We have explored in an animal model whether administration of DCs fused with poorly immunogenic carcinoma cells could elicit an antitumor response. Fusion of C57/BL6 mice bone marrow-derived DCs with Lewis lung carcinoma (LLC1) cells resulted in approximately 50% fusion efficiency. Hybrid cells (HCs) were used to explore 3 potential tumor therapy strategies: protective immunization, vaccination, and adoptive cellular therapy. Immunization with HCs induced activation of proliferating cytotoxic T cells, upregulation of distinct cytokines genes, and a significant retardation of tumor growth. Similar results were observed by vaccination with HCs in the tumor-bearing host. Finally, when T cells from HC-vaccinated mice were transferred into naive tumor-bearing mice, tumor growth was strongly retarded and an efficient proliferative and cytotoxic T-cell response was observed. Tumor growth was reduced by more than 50%, and tumor development was significantly delayed. Taken together, we demonstrate that HCs offer effective immunotherapy of poorly immunogenic carcinomas. This is independent of whether the HCs are taken for adoptive transfer or as a vaccine.