Immune and Inflammatory Cell Composition of Human Lung Cancer Stroma.

Recent studies indicate that the abnormal microenvironment of tumors may play a critical role in carcinogenesis, including lung cancer. We comprehensively assessed the number of stromal cells, especially immune/inflammatory cells, in lung cancer and evaluated their infiltration in cancers of different stages, types and metastatic characteristics potential. Immunohistochemical analysis of lung cancer tissue arrays containing normal and lung cancer sections was performed. This analysis was combined with cyto-/histomorphological assessment and quantification of cells to classify/subclassify tumors accurately and to perform a high throughput analysis of stromal cell composition in different types of lung cancer. In human lung cancer sections we observed a significant elevation/infiltration of total-T lymphocytes (CD3+), cytotoxic-T cells (CD8+), T-helper cells (CD4+), B cells (CD20+), macrophages (CD68+), mast cells (CD117+), mononuclear cells (CD11c+), plasma cells, activated-T cells (MUM1+), B cells, myeloid cells (PD1+) and neutrophilic granulocytes (myeloperoxidase+) compared with healthy donor specimens. We observed all of these immune cell markers in different types of lung cancers including squamous cell carcinoma, adenocarcinoma, adenosquamous cell carcinoma, small cell carcinoma, papillary adenocarcinoma, metastatic adenocarcinoma, and bronchioloalveolar carcinoma. The numbers of all tumor-associated immune cells (except MUM1+ cells) in stage III cancer specimens was significantly greater than those in stage I samples. We observed substantial stage-dependent immune cell infiltration in human lung tumors suggesting that the tumor microenvironment plays a critical role during lung carcinogenesis. Strategies for therapeutic interference with lung cancer microenvironment should consider the complexity of its immune cell composition.

5-HT2B receptor antagonists inhibit fibrosis and protect from RV heart failure.

OBJECTIVE: The serotonin (5-HT) pathway was shown to play a role in pulmonary hypertension (PH), but its functions in right ventricular failure (RVF) remain poorly understood. The aim of the current study was to investigate the effects of Terguride (5-HT2A and 2B receptor antagonist) or SB204741 (5-HT2B receptor antagonist) on right heart function and structure upon pulmonary artery banding (PAB) in mice. METHODS: Seven days after PAB, mice were treated for 14 days with Terguride (0.2 mg/kg bid) or SB204741 (5 mg/kg day). Right heart function and remodeling were assessed by right heart catheterization, magnetic resonance imaging (MRI), and histomorphometric methods. Total secreted collagen content was determined in mouse cardiac fibroblasts isolated from RV tissues. RESULTS: Chronic treatment with Terguride or SB204741 reduced right ventricular fibrosis and showed improved heart function in mice after PAB. Moreover, 5-HT2B receptor antagonists diminished TGF-beta1 induced collagen synthesis of RV cardiac fibroblasts in vitro. CONCLUSION: 5-HT2B receptor antagonists reduce collagen deposition, thereby inhibiting right ventricular fibrosis. Chronic treatment prevented the development and progression of pressure overload-induced RVF in mice. Thus, 5-HT2B receptor antagonists represent a valuable novel therapeutic approach for RVF.

Role of Src tyrosine kinases in experimental pulmonary hypertension.

OBJECTIVE: Pulmonary arterial hypertension is a progressive pulmonary vascular disorder with high morbidity and mortality. Compelling evidence suggests that receptor tyrosine kinases, such as platelet-derived growth factor (PDGF) are closely involved in the pathogenesis of pulmonary arterial hypertension. We investigated the effects of 2 novel PDGF inhibitors, nilotinib/AMN107 (Abl kinases/PDGF receptor inhibitor) and dasatinib/BMS-354825 (Abl kinases/PDGF receptor/Src inhibitor), on the proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs) and on the hemodynamics and pulmonary vascular remodeling in experimental pulmonary hypertension, and determined the expression and regulation of Src family kinases. METHODS AND RESULTS: Human PASMCs were stimulated by PDGF alone or multiple growth factors to induce proliferation and migration in vitro. Dasatinib (0.03 µmol/L), nilotinib (0.3 µmol/L), and imatinib (1 µmol/L) potently inhibited PDGF-induced signal transducer and activator of transcription 3 and Akt phosphorylation. All 3 inhibitors decreased PDGF-induced proliferation, cell cycle gene regulation, and migration. In contrast, only dasatinib inhibited multiple growth factor-induced PASMC proliferation, and this was associated with the inhibition of Src phosphorylation. Combination of specific Src inhibitors (phosphoprotein phosphatase 1, phosphoprotein phosphatase 2) with either imatinib or nilotinib reduced multiple growth factor-induced proliferation to a similar extent as dasatinib. Importantly, Src phosphorylation increased in pulmonary arterial hypertension PASMCs compared with control PASMCs. Finally, in vivo dasatinib (15 mg/kg per body weight) treatment caused a complete reversal of pulmonary vascular remodeling and achieved similar effectiveness as imatinib (100 mg/kg per body weight) in both monocrotaline- and hypoxia-induced pulmonary hypertension models. CONCLUSIONS: We suggest that dual inhibition of PDGF receptor and Src kinases potently inhibits mitogenic and motogenic responses to growth factors in PASMCs and pulmonary vascular remodeling in vivo so that dual inhibition may represent an alternative therapeutic approach for pulmonary arterial hypertension.

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.