Basic Science Studies
Funder – American Lung Association
Title – Role of PDLIM5 in the Pathogenesis of Pulmonary Hypertension
PDZ and LIM domain 5 (PDLIM5), also known as enigma homolog (ENH), is a ~64kDa cytoplasmic protein consisting of an N-terminal PDZ and three consecutive C-terminal LIM domains. It is one member of the PDZ-LIM protein family that is comprised of evolutionarily conserved proteins containing a PDZ domain and at least one LIM domain. The PDZ domain interacts with actin-binding proteins such as α-actinin and localizes the PDZ-LIM proteins and other complexed proteins to filamentous actin, while the LIM domains bind to diverse partners like signaling molecule PKC or transcriptional factor Id2 etc. Thus, the PDZ-LIM proteins function by sequestering nuclear factors in the cytoplasm. Combining two functional domains in one protein, it is not surprising that PDZ-LIM proteins have diverse functions and play important roles in development and maintaining physiological homeostasis. However, the role of PDZ-LIM proteins in the pathogenesis of pulmonary hypertension (PH) is unknown.
We found that PDLIM5 expression was upregulated in pulmonary arterial smooth muscle cells (PASMC) isolated from associated pulmonary arterial hypertension (APAH) patients, as well as that of mice or rats with established PH. Overexpression of PDLIM5 inhibited hypoxia-induced PH in mice in vivo, while smooth muscle cell (SMC)-specific knockout of PDLIM5 in mice enhanced hypoxia-induced pulmonary arterial remodeling. Based on these findings, we hypothesize that PDLIM5 expression in PASMC is induced as an adaptive response to the development of PH, so that it can function as an internal brake to inhibit the further progression of disease.
To test our hypothesis, we will investigate the downstream mechanisms by which PDLIM5 inhibits the progression of PH, as well as how it is regulated during the disease development. The findings will provide novel insights into PH, which may result in the design of novel therapeutic strategies for the treatment of the disease.
Funder – Gilead
Title – A protective role of miR-212-5p in pulmonary hypertension
Pulmonary hypertension (PH) is a devastating disease that results in a progressive increase in pulmonary vascular resistance, right ventricular failure, and ultimately death of patients. The endothelial and smooth muscle cells (EC and SMC) are two key cell types in the pulmonary vasculature. Crosstalk, like paracrine effects, between these two cell types plays an important role in maintaining the normal conditions of the vasculature and the pathogenesis of PH. However, the role of extracellular vesicle transfer between the two cell types and the exact mechanisms involved in the pathogenesis of PH are not well understood.
We found that under hypoxia, pulmonary artery EC (PAEC) release extracellular vesicles, specifically microvesicles (MV), that induce PASMC proliferation in vitro and PH in vivo, compared to that of normoxic PAEC. As we found that hypoxia exposure did not alter the number of PAECreleased MV, we reason that hypoxia exposure alters the cargo in PAEC-released MV and thereby their function to regulate PASMC proliferation and pathogenesis of PH. MicroRNAs (miRNAs, miRs) are small single-stranded non-coding RNAs and many of them have been identified to play important roles in disease development, including PH. Using miRNA deep sequencing analysis we found that, hypoxia exposure altered the miRNA cargo in PAEC-released MV: miR-210-3p level was increased, a miRNA that is known to stimulate SMC proliferation and induce PH. Meanwhile, hypoxia also induced a number of other miRNAs that inhibited SMC proliferation, principal among them being a novel miRNA, miR-212-5p, that had the highest inhibitory effect on SMC proliferation. Our data also showed that the endothelium and/or ECderived MV are critical for the induction of miR-212-5p in SMC in hypoxia as there was no induction of miRNA-212-5p in isolated SMC in hypoxia. Taking together, we hypothesize that EC-derived MV promote development of PH and vascular remodeling during hypoxia due to the presence of miRNA-210-3p but they may also provide a break against continued progression of the disease via anti-proliferative miRNAs, specifically miRNA-212-5p.
Funder – American Heart Association
Title – Role of endothelium-derived microvesicles in pulmonary hypertension
In the pulmonary vasculature, the pulmonary vascular endothelial cells (PVEC) and pulmonary artery smooth muscle cells (PASMC) are two key cell types that play a major role in the pathobiology of pulmonary hypertension (PH). As the “signal initiator” in the pulmonary vasculature, PVEC affect the function of PASMC by secreting bioactive agents, myoendothelial injunctions (MEJ) and/or releasing extracellular vesicles (EV) that contain various cargo components including proteins and RNAs etc., under both normal and pathological conditions. So far, our knowledge about the role of endothelial-derived EV and its cargo in the PASMC function and pathogenesis of PH is very limited. In this proposal, we will investigate the role of PVEC-derived microvesicles (MV), especially that of the miRNA cargo in these MV, in the pathogenesis of pulmonary vascular remodeling and PH. In preliminary studies we found that in hypoxia, MV released by mouse PVEC in culture (H-MV) induced mouse PASMC proliferation in vitro and pulmonary vascular remodeling and PH in mice in room air (vs MV released by mouse PVEC in normoxia, H-MV vs N-MV). Using miRNA deep sequencing, we identified 9 miRNAs that were significantly induced in H-MV (v.s. N-MV), including miR-210, a miRNA that is known to induce SMC proliferation and PH. Interestingly, all the other identified miRNAs either suppressed or did not alter SMC proliferation in vitro, including a novel miRNA, miR-212-5p, that had the strongest inhibitory effect on SMC proliferation. We also found that miR-212-5p played a protective role in the pathogenesis of hypoxia-induced PH in mice. Based on these findings, we hypothesize that the endothelium, via MV, promotes vascular remodeling during hypoxia but also provides a break against continued progression of the disease via releasing anti-proliferative miRNAs, such as miR-212, packaged in the MV.
Funder – Chancellor’s Proof of Concept Grant
Title – Sphingolipid signaling in Bronchopulmonary dysplasia
Bronchopulmonary dysplasia is a serious lung condition affecting the extreme preterm. There is no therapy yet for BPD and its sequela- wheezing.
We have shown that the drug, PF543 (a Sphingosine kinase 1 inhibitor) prevents BPD in animal models primarily by inhibiting formation of harmful oxygen free radicals within cells, thus helping the lungs regenerate to normalcy. This drug is also useful in preventing airway changes that causes severe wheezing. We intend develop PF543 as a new drug with the potential to treat not only BPD but also wheezing.
Funder – AHA
Title – Role of Sphingosine1 phosphate and S1P receptor1 mediated signaling in Bronchopulmonary Dysplasia
Bronchopulmonary Dysplasia (BPD) is a chronic lung disease of infancy that follows oxygen therapy and mechanical ventilation administered to premature newborns for respiratory insufficiency at birth. BPD leads on to pulmonary hypertension in infancy and reduced lung function as adults. Causation of BPD is primarily attributed to the premature exposure to high concentration of oxygen that impair angiogenesis in developing lungs affecting alveolarization. There is no therapy for this condition. We found that inhibiting Sphingosine Kinase 1 catalyzing formation of S1P protects from hyperoxia induced lung injury in the newborn. It has been recently noted that increased expression of S1P receptor 1 is associated with inhibition of angiogenesis. We have further noted that inhibition of S1P receptor 1 inhibits formation of reactive oxygen species. Genetically modified mice with reduced S1P receptor 1 (heterozygous) mice shows protection from oxygen induced lung injury. We are experimenting with chemicals inhibiting the receptor while looking into novel mechanisms of inhibition of angiogenesis. This project is likely serve as a platform for development of new drugs to prevent/treat BPD and hyperoxic lung injury in general.
Funder – NIH(Natl Institutes of Health)
Title – Role of novel SphK1 inhibitor, PF543 in therapy of Bronchopulmonary dysplasia and Airway remodeling
Preterm birth affects nearly 500,000 babies every year in North America and its incidence has risen by 36% over the last 25 years; extreme prematurity is more common among underserved communities, contributing to health disparity. Bronchopulmonary dysplasia (and its sequela – wheezing) is a serious lung condition for which there is no therapy yet, affecting the extreme preterm. In this proposal, we intend to develop PF543, a drug that has been shown to prevent BPD in animal models primarily by inhibiting formation of harmful oxygen free radicals within cells, thus helping the lungs regenerate to normalcy, and prevent airway changes that causes severe wheezing, as a new drug with the potential to treat not only BPD but also wheezing
Funder – NIH: NHLBI
Title – Role of MicroRNA-17-92 and PDLIM5 Signaling in Pulmonary Arterial Hypertension
This project aims to elucidate the molecular mechanisms underlying the microRNA-17~92/PDLIM5 signaling-mediated pulmonary artery smooth muscle cell phenotype change and its functional impact in the genesis of pulmonary hypertension. We are continuing to investigate the role of PDLIM5 in the metabolic shift and to carry out a PDLIM5-targeted drug development process for the treatment of pulmonary hypertension.
Funder – NIH: NHLBI
Title – Role of Nrf2 in Alveolar Epithelial Cell Regeneration During Lung Repair
Alveolar epithelial cell (AEC) regeneration following acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) is essential for homeostasis. In case of impaired repair, the inflammatory response is unchecked and lung inflammation and tissue repair do not normally resolve. Hyperoxia is widely used in the treatment of critical ill (COPD and ARDS) patients but the effects of this pro- oxidant exposure on alveolar epithelium in these patients are not clearly understood. Likewise, abnormal lung AEC repair caused by bacterial infection is a major health concern. The proposed studies will define the mechanisms of AEC-specific Nrf2 signaling in regulating the lung’s pro-resolution response and repair, and whether GSH/AKT imbalance is a causative factor in aberrant repair of alveolar epithelium after injury. We test the postulate that activating pro-resolution Nrf2 pathway will accelerates the resolution of lung injury using hyperoxia- and bacterial infection-induced models of lung injury. alveolar epithelium
Funder – NIH/NIGMS
Title – Fra-1 – A20 Signaling and Resolution of Pneumonia-Induced Sepsis
The counter balancing of pro- and anti-inflammatory gene transcription is crucial for normal homeostasis after septic tissue injury. Aberrant regulation of this transcriptional balance culminates in an unchecked systemic inflammation, leading to lung tissue damage and edema, respiratory failure and ultimately death. However, the exact mechanisms underlying pathological inflammation in sepsis are poorly understood, and thus the strategies to accelerate the resolution of sepsis are very limited. Studies in the proposal will test the novel hypothesis that pathogenic signaling caused by sepsis is the result of a macrophage-specific Fra-1/AP-1 restricted expression of anti- inflammatory A20, a crucial ubiquitin-editing enzyme that terminates uncontrolled activation of NF- κB and MAP kinase signaling. The proposed studies will offer novel insights and targets for therapies to accelerate lung injury repair in patients with pseudomonas pneumonia and sepsis.
Funder – Acetylon Pharmaceuticals Inc
Title – Effective HUDEP Inhibitors on HbF
Funder – NIH: NHLBI
Title – Mitophagy as Potential Target in Sickle Cell Disease
Funder – M.R. Bauer Foundation
Title – Sickle Cell Transition Program
Individuals with sickle cell disease suffer from chronic hemolytic anemia, vaso-occlusive pain crises, multisystem organ damage, and a shortened lifespan. The disease is caused by a mutation of the β-globin gene; this mutation allows for the polymerization of the sickle hemoglobin (HbS) when deoxygenated. Many patients are lost to healthcare follow-up during the transition from pediatric to adult care. The peer patient advocate is an individual with Sickle Cell Disease who serves as a community health worker. The peer patient advocate builds relationships and connections with patients, families, and the sickle cell community. The peer patient advocate will be closely connected to patients and families and will participate in the following areas of care: 1) group care sessions as facilitator 2) Sickle cell transition fair coordination 3) Visiting pediatric patients in hospital and clinic. The advocate will assist with the transition of the medical, social, and professional lives of adolescents living with Sickle Cell disease from pediatric to adult care.