Pulmonary vascular disease (PVD) and lung hypoplasia (LH) are the two main causes of mortality and morbidity in patients with congenital diaphragmatic hernia (CDH). Previous studies have shown that remodeling of the extracellular matrix (ECM) by elastase and matrix metalloproteinase (MMP) enzymes, concomitant with smooth muscle cell (SMC) proliferation and deposition of ECM proteins and growth factors, leads to primary pulmonary hypertension (PH) and that blockade of this pathway results in disease reversal. The aim of our study is to determine whether a similar pathway is induced in the PVD associated with CDH and to verify whether its inhibition will lead to reversal of PVD. Firstly, we confirmed various aspects of PVD in the nitrofen induced CDH rat model. These included: left lung hypoplasia, right ventricular hypertrophy, and increased arterial smooth muscle wall thickness alongside decreases in arterial lumen area and total number of distal pulmonary vessels. We also showed increases in elastase and matrix metalloproteinase (MMP) enzyme activities within distal pulmonary arteries (PAs), which, we were able to inhibit using serine elastase (sivelestat, elafin, and serpina1) and MMP (GM6001) inhibitors. Furthermore, we confirmed increased SMC proliferation and deposition of osteopontin (OPN) and epidermal growth factor (EGF) within the diseased vasculatures. We are now working on using sivelestat and GM6001 pharmaceuticals as well as endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) modified to express elafin and serpina1 to determine their abilities to reverse the PVD associated with CDH. This project is part of our translational research program with the ultimate goal of developing a novel strategy of targeting PVD in infants with CDH to improve patient survival and long-term outcome.

Norfloxacin For Hepatopulmonary Syndrome: A Pilot Study of a Rare Disease Samir Gupta, Masters of Science, 2008 Graduate Department of Health Policy, Management and Evaluation University of Toronto Introduction: Hepatopulmonary Syndrome is a rare disease characterized by abnormal gas-exchange and a poor prognosis, with no known effective medical therapy. A rat model and preliminary human data suggest that this disease may be caused by intestinal bacterial overgrowth, systemic endotoxemia and increased nitric oxide. Methods: We conducted a pilot crossover randomized controlled trial of norfloxacin versus placebo over four weeks, in seven subjects with HPS or a milder condition called pre-HPS, with a primary outcome of alveolar-arterial oxygen gradient (AaDO2). Results: There was no trend toward improved AaDO2, this outcome and other intermediate outcomes were highly variable, and results suggested that a longer treatment course might be necessary. We identified multiple obstacles to recruitment. Conclusion: We believe that a full-scale study of norfloxacin therapy for HPS will require 1) a six-month therapeutic period, 2) more specific HPS diagnostic criteria for clinical and study populations, and 3) creative recruitment maneuvers.

Norfloxacin For Hepatopulmonary Syndrome: A Pilot Study of a Rare Disease Samir Gupta, Masters of Science, 2008 Graduate Department of Health Policy, Management and Evaluation University of Toronto Introduction: Hepatopulmonary Syndrome is a rare disease characterized by abnormal gas-exchange and a poor prognosis, with no known effective medical therapy. A rat model and preliminary human data suggest that this disease may be caused by intestinal bacterial overgrowth, systemic endotoxemia and increased nitric oxide. Methods: We conducted a pilot crossover randomized controlled trial of norfloxacin versus placebo over four weeks, in seven subjects with HPS or a milder condition called pre-HPS, with a primary outcome of alveolar-arterial oxygen gradient (AaDO2). Results: There was no trend toward improved AaDO2, this outcome and other intermediate outcomes were highly variable, and results suggested that a longer treatment course might be necessary. We identified multiple obstacles to recruitment. Conclusion: We believe that a full-scale study of norfloxacin therapy for HPS will require 1) a six-month therapeutic period, 2) more specific HPS diagnostic criteria for clinical and study populations, and 3) creative recruitment maneuvers.