pyrimidinones and Bronchopulmonary-Dysplasia

Bronchopulmonary dysplasia (BPD) is the most common and serious chronic lung disease of premature infants. Connective tissue growth factor (CTGF) plays an important role in tissue development and remodeling. We have previously shown that targeted overexpression of CTGF in alveolar type II epithelial cells results in BPD-like pathology and activates β-catenin in neonatal mice.. Utilizing this transgenic mouse model and ICG001, a specific pharmacological inhibitor of β-catenin, we tested the hypothesis that β-catenin signaling mediates the effects of CTGF in the neonatal lung. Newborn CTGF mice and control littermates received ICG001 (10 mg/kg/dose) or placebo (dimethyl sulfoxide, equal volume) by daily i.p. injection from postnatal day 5 to 15. Alveolarization, vascular development, and pulmonary hypertension (PH) were analyzed.. Administration of ICG001 significantly downregulated expression of cyclin D1, collagen 1a1, and fibronectin, which are the known target genes of β-catenin signaling in CTGF lungs. Inhibition of β-catenin signaling improved alveolar and vascular development and decreased pulmonary vascular remodeling. More importantly, the improved vascular development and vascular remodeling led to a decrease in PH.. β-Catenin signaling mediates the autocrine and paracrine effects of CTGF in the neonatal lung. Inhibition of CTGF-β-catenin signaling may provide a novel therapy for BPD.

Topics: Animals; Animals, Newborn; beta Catenin; Bridged Bicyclo Compounds, Heterocyclic; Bronchoalveolar Lavage; Bronchopulmonary Dysplasia; Collagen Type I; Collagen Type I, alpha 1 Chain; Connective Tissue Growth Factor; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Fibronectins; Hyperoxia; Hypertension, Pulmonary; Intracellular Signaling Peptides and Proteins; Lung; Mice; Mice, Transgenic; Pulmonary Alveoli; Pyrimidinones; Signal Transduction

Bronchopulmonary dysplasia (BPD) is the most common and serious chronic lung disease of preterm infants. The development of pulmonary hypertension (PH) significantly increases the mortality and morbidity of this disease. β-Catenin signaling plays an important role in tissue development and remodeling. Aberrant β-catenin signaling is associated with clinical and experiment models of BPD. To test the hypothesis that inhibition of β-catenin signaling is beneficial in promoting alveolar and vascular development and preventing PH in experimental BPD, we examined the effects of ICG001, a newly developed pharmacological inhibitor of β-catenin, in preventing hyperoxia-induced BPD in neonatal rats. Newborn rat pups were randomized at postnatal day (P)2 to room air (RA) + DMSO (placebo), RA + ICG001, 90% FiO2 (O2) + DMSO, or O2 + ICG001. ICG001 (10 mg/kg) or DMSO was given by daily intraperitoneal injection for 14 days during continuous exposure to RA or hyperoxia. Primary human pulmonary arterial smooth muscle cells (PASMCs) were cultured in RA or hyperoxia (95% O2) in the presence of DMSO or ICG001 for 24 to 72 hours. Treatment with ICG001 significantly increased alveolarization and reduced pulmonary vascular remodeling and PH during hyperoxia. Furthermore, administering ICG001 decreased PASMC proliferation and expression of extracellular matrix remodeling molecules in vitro under hyperoxia. Finally, these structural, cellular, and molecular effects of ICG001 were associated with down-regulation of multiple β-catenin target genes. These data indicate that β-catenin signaling mediates hyperoxia-induced alveolar impairment and PH in neonatal animals. Targeting β-catenin may provide a novel strategy to alleviate BPD in preterm infants.

Topics: Animals; Animals, Newborn; Apoptosis; beta Catenin; Blotting, Western; Bridged Bicyclo Compounds, Heterocyclic; Bronchopulmonary Dysplasia; Cell Proliferation; Disease Models, Animal; Extracellular Matrix; Fluorescent Antibody Technique; Humans; Hyperoxia; Hypertension, Pulmonary; Immunoenzyme Techniques; Myocytes, Smooth Muscle; Pulmonary Alveoli; Pyrimidinones; Rats; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger