Prenatal Maternal Lipopolysaccharide and Mild Newborn Hyperoxia Increase Intrapulmonary Airway but Not Vessel Reactivity in a Mouse Model

Oxygen and mechanical stretch in the developing lung: risk factors for neonatal and pediatric lung disease

Chronic airway diseases, such as wheezing and asthma, remain significant sources of morbidity and mortality in the pediatric population. This is especially true for preterm infants who are impacted both by immature pulmonary development as well as disproportionate exposure to perinatal insults that may increase the risk of developing airway disease. Chronic pediatric airway disease is characterized by alterations in airway structure (remodeling) and function (increased airway hyperresponsiveness), similar to adult asthma. One of the most common perinatal risk factors for development of airway disease is respiratory support in the form of supplemental oxygen, mechanical ventilation, and/or CPAP. While clinical practice currently seeks to minimize oxygen exposure to decrease the risk of bronchopulmonary dysplasia (BPD), there is mounting evidence that lower levels of oxygen may carry risk for development of chronic airway, rather than alveolar disease. In addition, stretch exposure due to mechanical ventilation or CPAP may also play a role in development of chronic airway disease. Here, we summarize the current knowledge of the impact of perinatal oxygen and mechanical respiratory support on the development of chronic pediatric lung disease, with particular focus on pediatric airway disease. We further highlight mechanisms that could be explored as potential targets for novel therapies in the pediatric population.

Insights into the Black Box of Intra-Amniotic Infection and Its Impact on the Premature Lung: From Clinical and Preclinical Perspectives

Intra-amniotic infection (IAI) is one major driver for preterm birth and has been demonstrated by clinical studies to exert both beneficial and injurious effects on the premature lung, possibly due to heterogeneity in the microbial type, timing, and severity of IAI. Due to the inaccessibility of the intra-amniotic cavity during pregnancies, preclinical animal models investigating pulmonary consequences of IAI are indispensable to elucidate the pathogenesis of bronchopulmonary dysplasia (BPD). It is postulated that on one hand imbalanced inflammation, orchestrated by lung immune cells such as macrophages, may impact on airway epithelium, vascular endothelium, and interstitial mesenchyme, resulting in abnormal lung development. On the other hand, excessive suppression of inflammation may as well cause pulmonary injury and a certain degree of inflammation is beneficial. So far, effective strategies to prevent and treat BPD are scarce. Therapeutic options targeting single mediators in signaling cascades and mesenchymal stromal cells (MSCs)-based therapies with global regulatory capacities have demonstrated efficacy in preclinical animal models and warrant further validation in patient populations. Ante-, peri- and postnatal exposome analysis and therapeutic investigations using multiple omics will fundamentally dissect the black box of IAI and its effect on the premature lung, contributing to precisely tailored and individualized therapies.

Rho-kinase inhibitors protect against neonatal hyperoxia-induced airway hyperreactivity in a rat pup model: Role of prostaglandin F2α

BACKGROUND

Oxygen therapy in preterm neonates is associated with airway hyperreactivity. The role of Rho/Rho-kinase smooth muscle signaling in hyperoxia-induced airway hyperreactivity remains understudied. We hypothesized that inhibition of Rho-kinase will attenuate airway hyperreactivity induced by neonatal hyperoxia.

METHODS

Newborn rats were raised in hyperoxia (>95% O₂ ) or ambient air (AA) for 7 days. Subgroups were injected with a Rho-kinase inhibitor: Y-27632 (10 mg·kg^-1 ·day^-1 ) or fasudil (10 mg·kg^-1 ·day^-1 ), or a FP receptor antagonist - AS604872 (30 mg·kg^-1 ·day^-1 ). After exposures, tracheal cylinders were prepared for in vitro wire myography. Contraction to methacholine or PGF_2α was measured in the presence or absence of tissue-bath Y-27632, fasudil, or AS604872. Lung PGF_2α levels, Rho-kinase protein level and Rho-kinase 1 activity were measured by ELISA.

RESULTS

Tracheal smooth muscle contraction was significantly greater in hyperoxic compared to AA groups. Both, Y-27632 and fasudil significantly decreased contractility to MCh or PGF_2α in hyperoxic groups versus hyperoxic controls (p < 0.001), but did not alter AA group responses. Inhibition of FP receptors attenuated responses to PGF_2α . Hyperoxia significantly increased lung PGF_2α compared to AA (p < 0.01), but Rho-kinase inhibition did not influence PGF_2α level. Rho-kinase protein level (p < 0.001) and activity (p < 0.01), were increased by hyperoxia, but blockade of FP receptor reduced the Rho-kinase 1 activity (p < 0.05) under hyperoxic condition.

CONCLUSIONS

This study demonstrates an active role of Rho/Rho-kinase signaling on hyperoxia-induced airway hyperreactivity. These findings suggest that Rho-kinase inhibitors might serve as an effective therapy for hyperoxia-induced airway hyperreactivity.