Connective Tissue Growth Factor Antibody Therapy Attenuates Hyperoxia-Induced Lung Injury in Neonatal Rats

Abstract

Despite recent advances in neonatal intensive care and surfactant therapy, bronchopulmonary dysplasia (BPD) continues to be one of the most common long-term pulmonary complications associated with preterm birth. Clinical efforts to prevent and treat BPD have been largely unsuccessful due to its multifactorial nature and poorly understood disease process. Connective tissue growth factor (CTGF) is a matricellular protein that plays an important role in tissue development and remodeling. Previous studies have demonstrated that hyperoxia exposure up-regulates CTGF expression in neonatal rat lungs. Whether CTGF overexpression plays a role in the pathogenesis of BPD, and whether CTGF antagonism has a therapeutic potential for BPD, are unknown. In the present study, we examined CTGF expression in lung autopsy specimens from patients with BPD and control subjects with no BPD. We assessed the effect of a CTGF-neutralizing monoclonal antibody (CTGF Ab) on preventing hyperoxia-induced lung injury in neonatal rats. Our study demonstrates that CTGF expression is increased in BPD lungs. In newborn rats, exposure to 90% oxygen for 14 days resulted in activation of β-catenin signaling, decreased alveolarization and vascular development, and physiological and histological evidence of pulmonary hypertension (PH). However, treatment with CTGF Ab prevented β-catenin signaling activation, improved alveolarization and vascular development, and attenuated PH during hyperoxia. These data indicate that CTGF-β-catenin signaling plays a critical role in the pathogenesis of experimental BPD. CTGF antagonism may offer a novel therapeutic strategy to alleviate BPD and PH in neonates.

Inhibition of β-catenin signaling protects against CTGF-induced alveolar and vascular pathology in neonatal mouse lung

“…We showed here that the increased pulmonary vascularization and decreased vascular remodeling by β-catenin inhibition leads to decreased RVSP and RVH, suggesting decreased PH. These data are consistent with our previous studies in hyperoxia-induced neonatal lung injury model that treatment with CTGF-neutralizing antibodies and ICG001decreased PH (6,18). PH is often associated with severe BPD.…”

“…Activation of ILK and LRP5/6 can lead to nuclear translocation of β-catenin and subsequent activation of target gene transcription. We and others have previously demonstrated that β-catenin signaling is increased in the lungs of hyperoxia-exposed neonatal rats, a widely used experimental model of BPD (6,24). A recent study demonstrated that increased β-catenin is present in the mesenchymal stromal cells isolated from infants developing BPD and in α-SMA-positive myofibroblasts in the lungs of infants dying of BPD (25).…”

“…Recent studies have highlighted the potential role of CTGF in BPD development and progression. The clinical association of CTGF with BPD is best established by studies demonstrating increased CTGF concentrations in bronchoalveolar lavage fluid from preterm infants developing BPD (5) and increased CTGF expression in lung tissues of infants who died of BPD (6). Multiple studies have examined the potential role of CTGF in experimental BPD and demonstrated that increased CTGF expression is associated with chronic hyperoxia as well as mechanical ventilationinduced lung injury in neonatal rodents (6)(7)(8)(9)(10).…”

Pentoxifylline and prevention of hyperoxia-induced lung ­injury in neonatal rats

“…Furthermore, anti-CTGF therapy attenuates hyperoxia-induced alveolar damage and vascular remodeling (31). Multiple studies in kidney and liver have demonstrated that PTX downregulates the expression of CTGF (32,33); therefore, we expected that PTX would decrease CTGF expression and lung fibrosis during hyperoxia.…”

“…Pups were delivered naturally at term gestation, pooled, and randomly assigned to three groups to receive RA plus placebo, NS (RA + NS); hyperoxia (>95% O 2 ) plus NS (O 2 + NS); or hyperoxia plus PTX (O 2 + PTX; Aventis Pharma, Mexico City, Mexico). Hyperoxia was achieved in a sealed Plexiglas chamber as previously described (31). PTX (75 mg/kg equivalent to 3.75 ml/kg) based on the efficacy and safety data previously reported by ter Horst et al (21) or NS (same volume) was given via subcutaneous injection before O 2 exposure and then twice a day during continuous exposure to RA or O 2 for 4-9 d. Dams were rotated daily between RA and O 2 to avoid oxygen toxicity.…”