sar131675 and Disease-Models--Animal

Topics: Animals; Biopsy; Cell Line, Tumor; Cell Proliferation; Disease Models, Animal; Gene Expression Profiling; Human Umbilical Vein Endothelial Cells; Humans; Indoles; Lymph Nodes; Lymphoma; Lymphotoxin beta Receptor; Lymphotoxin-alpha; Mice; Mice, Transgenic; Naphthalenes; Naphthyridines; Neovascularization, Pathologic; Signal Transduction; Tumor Microenvironment; Vascular Endothelial Growth Factor C; Vascular Endothelial Growth Factor Receptor-3; Xenograft Model Antitumor Assays

Chronic inflammation induces lymphangiogenesis and blood vessel remodelling. Since aged pneumonia patients often have repeated episodes of aspiration pneumonia, the pathogenesis may involve chronic inflammation. For lymphangiogenesis, VEGFR-3 and its ligand VEGF-C are key factors. No previous studies have examined chronic inflammation or vascular changes in aspiration pneumonia or its mouse models. In lung inflammation, little is known about the effect of blocking VEGFR-3 on lung lymphangiogenesis and, moreover, its effect on the disease condition. This study aimed to establish a mouse model of aspiration pneumonia, examine the presence of chronic inflammation and vascular changes in the model and in patients, and evaluate the effect of inhibiting VEGFR-3 on the lymphangiogenesis and disease condition in this model. To induce aspiration pneumonia, we repeated inoculation of pepsin at low pH and LPS into mice for 21-28 days, durations in which bronchioalveolar lavage and plasma leakage in the lung suggested the presence of exaggerated inflammation. Conventional and immunohistochemical analysis of tracheal whole mounts suggested the presence of chronic inflammation, lymphangiogenesis, and blood vessel remodelling in the model. Quantitative RT-PCR of the trachea and lung suggested the involvement of lymphangiogenic factor VEGF-C, VEGFR-3, and pro-inflammatory cytokines. In the lung, the aspiration model showed the presence of chronic inflammation and exaggerated lymphangiogenesis. Treatment with the VEGFR inhibitor axitinib or the VEGFR-3 specific inhibitor SAR131675 impaired lymphangiogenesis in the lung and improved oxygen saturation in the aspiration model. Since the lung is the main site of aspiration pneumonia, the changes were intensive in the lung and mild in the trachea. Human lung samples also showed the presence of chronic inflammation and exaggerated lymphangiogenesis, suggesting the relevance of the model to the disease. These results suggest lymphatics in the lung as a new target of analysis and therapy in aspiration pneumonia.

Topics: Animals; Autopsy; Axitinib; Chronic Disease; Cytokines; Disease Models, Animal; Humans; Imidazoles; Indazoles; Inflammation Mediators; Lung; Lymphangiogenesis; Lymphatic Vessels; Male; Mice, Inbred C57BL; Naphthyridines; Pneumonia, Aspiration; Protein Kinase Inhibitors; Time Factors; Vascular Endothelial Growth Factor C; Vascular Endothelial Growth Factor Receptor-3

The functions of vascular endothelial growth factor C (VEGF-C) and the VEGF receptor 3 (VEGFR-3) in the nervous system are not well known. In this study, we examined the role of VEGF-C and VEGFR-3 in ischemic preconditioning (IPC)-induced tolerance in the mouse hippocampus. Adult male C57BL/6 mice were subjected to either severe ischemia (SI) induced by 40 min of bilateral common carotid artery occlusion (BCCAO) with or without IPC (5-min BCCAO) or IPC only. Cerebral blood flow was measured during ischemic periods using laser Doppler flowmetry. Neuronal damage was assessed histologically, and VEGF-C and VEGFR-3 expression levels were assessed through immunostaining. Fluoro-Jade B-labeled cells were abundant in the CA1 area 7 days after SI without IPC (sham+SI group), whereas cells were rarely labeled in mice subjected to IPC followed by SI (IPC+SI group). Similarly, the number of neuronal nuclei (NeuN)-positive cells in the CA1 area was significantly lower in the sham+SI group than in the IPC+SI group. Interestingly, we found that sublethal IPC treatment induced prominent VEGF-C expression in the CA1 pyramidal neurons and VEGFR-3 expression in the stratum radiatum and stratum lacunosum moleculare after 3 days of reperfusion that were sustained for 7 days. Moreover, VEGF-C immunoreactivity was also markedly increased, whereas VEGFR-3 expression was sustained in tolerance-acquired CA1 neurons after SI. Application of a VEGFR-3 inhibitor, SAR131675, abolished the IPC-induced neuroprotection in a dose-dependent manner in the mouse hippocampus. These results suggest that VEGF-C/VEGFR-3 signaling is associated with IPC-induced hippocampal tolerance to lethal ischemia.

Topics: Animals; Brain Ischemia; CA1 Region, Hippocampal; Carotid Artery Diseases; Cell Count; Central Nervous System Agents; Disease Models, Animal; DNA-Binding Proteins; Dose-Response Relationship, Drug; Fluoresceins; Fluorescent Antibody Technique; Ischemic Preconditioning; Male; Mice, Inbred C57BL; Naphthyridines; Nerve Tissue Proteins; Neurons; Nuclear Proteins; Vascular Endothelial Growth Factor C; Vascular Endothelial Growth Factor Receptor-3