Novel Drugs for the Treatment of BPD
Currently there are no specific or effective treatments for BPD. Vitamin A, caffeine, and steroids are being used with modest benefits. We have shown that small molecules like miRNA inhibitors and chitohexaoses can be used as potential therapies to prevent/ameliorate this disease. We are currently exploring these molecules in larger animal models in an attempt to assess the translational potential for use in humans.
Sex Differences in BPD
Sex-specific differences exist in the development and the severity of BPD. BPD affects male infants more severely than their female counterparts. This effect has been attributed to the protective effects of estradiol, known as the “estrogen paradox”. However, based on our novel findings, it would appear that sex hormones alone are insufficient to explain the marked sex bias observed in BPD, and that other unexplained and unexplored mechanisms exist. We are trying to unravel the underlying cause for these sex-biased diseases so that there is a targeted personalized therapeutic approach for males and females individually, soon after birth.
BPD-associated Pulmonary Hypertension
Infants with BPD are also predisposed to abnormal growth of pulmonary vasculature with dysregulated pulmonary vascular density and increased pulmonary vascular resistance. Chronic hyperoxia in infants with BPD leads to vascular remodeling with intimal hyperplasia in this dysregulated pulmonary vasculature, which contributes to pulmonary hypertension in infants with BPD, characterized by right ventricular hypertrophy. We use echocardiography, histology and immunostaining to show the changes in vascular re-modeling in various mouse models of BPD-associated pulmonary hypertension.
Novel Biomarkers in BPD
There is no reliable biomarker that can help diagnose BPD and monitor response to therapy in infants with BPD and BPD-associated pulmonary hypertension. Identification of a biomarker that can be used in the setting of BPD to identify the infants most at risk for developing these conditions will greatly facilitate the management of these infants. Based on the pathogenesis of BPD and data from previous animal and human studies, we have identified various molecules such as cytokines, chemokines, chloride ion channels, microRNAs etc. that have the potential for acting as a biomarker for BPD and its complications such as pulmonary hypertension.
Small RNAs as Regulatory Molecules in BPD
After it was discovered that miRNAs play an important role in the pathogenesis of BPD, we were the first to report that miR34a has a major role in the pathogenesis of BD. Since then several miRNAs have been identified to be involved in the various regulatory pathways that control the progression of this disease. Using microarrays and deep RNA sequencing we have been able to identify several short and long non-coding RNAs, circular RNAs and more novel miRNAs to be involved in this disease.
Regulatory Pathways in BPD
Inflammation, arrested alveolarization, decreased cell proliferation, increased apoptosis, dysregulated angiogenesis, mitochondrial dysfunction are some of the key hallmark processes associated with BPD and BPD-associated pulmonary hypertension. Using various null mutant (knockout) and transgenic mouse models, we try to decipher the different regulatory genes involved in these processes and manipulate these processes so as to restore the above pathways to normalcy.
Neurodevelopmental Changes in BPD
Children with BPD exhibit low average IQ, academic difficulties, delayed speech and language development, visual-motor integration impairments, and behavior problems. These children display attention problems, memory and learning deficits, and executive dysfunction. Neuropsychological studies are sparse and using neonatal mice pups, we have shown morphological changes in the cerebellum and hippocampus region of the brain after hyperoxia exposure. Glial fibrillary acidic protein (GFAP) – the most common marker for astrocytes is severely reduced in the hyperoxia-induced BPD mouse model as compared to the room air controls. Similarly, several behavioral assessments (novel object identification, water maze testing, open field testing, light and dark box movements) have revealed significant changes in the hyperoxia-induced BPD mouse model, when compared to the control group.
Post-translational Modifications (PTMs ) in BPD
PTMs (phosphorylation, ubiquitination, nitrosylation, glycosylation) regulate the activity, localization, and interaction of proteins with other cellular proteins, nucleic acids, lipids and cofactors by undergoing chemical modifications in the structure in response to stress, which is hyperoxia in the context of BPD. The characterization of PTMs, although challenging, provides invaluable insight into the cellular functions underlying etiological processes. These modifications may either be beneficial or harmful. We have identified some novel pathways in these PTMs that can be targeted to develop therapies for BPD.
Cellular Organelle Dysfunction in BPD
The pulmonary alveolar developmental impairment is strongly associated with cell organelle dysfunction including mitochondrial dysfunction and endoplasmic reticulum (ER) stress in the developing lung subjected to stress (hyperoxia exposure, mechanical ventilation, infection etc.). Our research focus in this area is to understand the crosstalk between hyperoxia-induced mitochondrial dysfunction and cell stress in the development of BPD. We are utilizing genetic, molecular, and cellular experimental approaches that include fetal lung epithelial/endothelial cell lines, mice, and human lung tissue to answers these questions.
Senescence in BPD
The BPD pulmonary phenotype is characterized by impaired lung development affecting both normal alveologenesis and the pulmonary vascularization. However, endogenous mechanisms that lead to failed lung regeneration after hyperoxia mediated injury and postnatal lung development are unknown. We reasoned that abnormal lung development may be associated with disabled cell proliferation due to the induction of senescence as a survival adaptive mechanism in a hyperoxia environment. The major objective of this project is to elucidate the mechanism by which hyperoxia impairs pulmonary alveolarization and hampers lung development. We are utilizing senescence lung type II alveolar epithelial cells (TIIAECs) specific conditional knockout (KO) p21 and p16 mice to understand the role of cellular senescence in arrested lung development and abnormal physiological functioning of lungs.