Moin Vera, MD, PhD
Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center
“The role of angiotensin II-mediated inflammation in MPS I vascular disease: a study of pathophysiologic mechanism and evaluation of angiotensin receptor blockade therapy”
The goal of this project is to study whether inflammation caused by angiotensin II is an important contributor to vascular disease in MPS I, and whether blocking the angiotensin II pathway will reduce the severity of vascular disease in MPS I mice. Vascular disease in MPS I consists of uncontrolled proliferation of smooth muscle cells and disruption of connective tissue in the walls of arteries causing thickening, stiffening and progressive blockage of blood flow. We have observed increased expression of angiotensin II and increased activity of the inflammatory pathway it stimulates in the aortas of MPS I canines and are now studying this process in MPS I mice. This project began on August 1, 2014. Year 1 milestones achieved include: 1) establishment of a MPS I mouse colony in our laboratory; 2) harvesting the descending aortas in groups of unaffected control mice and untreated MPS I mice for characterization of the natural history of vascular disease; 3) and initiation of treatment with the angiotensin II receptor blocker losartan, the recombinant human enzyme laronidase, and a combination of the two in three separate groups of MPS I and control mice. In year 2 we plan to complete the 16-week treatment period for these groups of mice and study and compare the descending aortas of mice in each group for markers of angiotensin II mediated inflammation. In parallel, we will begin studying the angiotensin II inflammatory pathway in cultures of vascular smooth cells produced from mice in these groups. These experiments will provide biomarkers for angiotensin II mediated inflammation that will help us detect and monitor vascular disease in MPS I patients, and they will help us assess whether treatment with losartan could be effective and useful for these patients.
R. Scott McIvor, PhD
University of Minnesota
“AAV mediated gene transfer to the CNS for MPS II”
The specific goal of this project has been to test for correction of iduronate sulfatase (IDS) deficiency and prevention of neurocognitive dysfunction in MPS II mice after CNS-directed administration of AAV serotype 9 encoding human IDS. During the first year of these studies, we found surprisingly low levels of IDS activity in the brain after intrathecal delivery of AAV9-IDS. However, intracerebroventricular (ICV) delivery of AAV9-IDS in MPS II mice resulted in wild-type levels of IDS activity in the brain, coupled with reduced levels of glycosaminoglycan storage. In the coming year we are testing expanded cohorts of MPS II mice for improved neurocognitive function after ICV delivery of AAV- IDS vector. Results from these studies will provide a model for CNS-directed IDS gene therapy for MPS II in humans.
Beverly Davidson, PhD
The Children’s Hospital of Philadelphia
“Overcoming limitations inherent in sulfamidase to improve MPS IIIA gene therapy”
The goal of this project is to use genetic methods to modify Heparan N-Sulfatase (HNS) to improve secretion to provide for greater therapeutic benefit in MPS IIIA treatment. During the first year of study, we screened five mannose 6 phosphorylation (M6P) sites and three ubiquitination sites and found one M6P site modification that resulted in elevated levels of enzyme secretion. Further studies showed this modification afforded several interesting features on this novel enzyme variant. First, it not only increased enzyme secretion, but also decreased enzyme buildup in the cells, which, if there was buildup, could impart secondary lysosomal dysfunction. Secondly, this variant is processed correctly in the cells and matures to the active form in the lysosome. Third, it appears to be more efficiently taken up from the media, using a receptor different than that used for the normal, unmodified enzyme. As a result, we propose that this modified HNS will perform better than the wild type HNS in gene therapy or enzyme replacement therapy for MPS IIIA patients. In the following year, we plan to advance this work to mouse studies, to further exam its utility in gene and enzyme replacement therapy. We also plan to clarify the unknown receptor responsible for the uptake of this modified protein. These studies will advance our therapeutic options for MPS IIIA therapy.
Calogera Simonaro, PhD
Icahn School of Medicine at Mount Sinai
New York, NY
“Pentosan Polysulfate and GAGs in MPS”
We have previously shown that the pro-inflammatory signaling caused by accumulation of glycosaminoglycans (GAGs) is a common pathologic mechanism in the mucopolysaccharidoses (MPS) that can be modulated through treatment with pentosan polysufate (PPS). In addition to reducing inflammation, MPS I dogs (manuscript in preparation) and MPS VI rats (Simonaro et al., 2013; Frohbergh et al., 2014) treated with PPS also reduced GAG accumulation both systemically and in tissues. The mechanism(s) leading to PPS-induced GAG reduction in MPS is unknown, nor is it known if the same effects could be achieved in other MPS types.
We have therefore treated four different types (I, II, IV and VI) of human MPS skin fibroblasts with PPS and performed mass spectrometry and dye-binding assays to measure GAG accumulation. The initial results have shown the GAG reducing ability of PPS in all MPS types, with a preferential reduction of over 50% in MPS VI cells. We have also studied expression of genes involved in GAG synthesis and other genes involved in lysosomal biogenesis, since activation of this pathway has been shown to result in GAG clearance. Quantitative PCR analysis was performed using PPS treated and untreated human fibroblasts from the four different MPS types. The results have shown an up-regulation of genes involved in the synthetic GAG pathway, such as HS6T1 and NDST1 in untreated MPS cells, and a normalization/trend towards normal in treated cells. Further analysis including electron microscopy of the lysosomes in the treated MPS cells is underway.
Safety and efficacy also was shown in two adult safety trials that were conducted in collaboration with the Universities of Mainz, Germany (MPS I) and Gifu, Japan (MPS II). Based on these small proof-of-concept studies, as well as the animal results, we propose that PPS could be an effective, simple and safe therapy for MPS patients that could provide substantial clinical benefit alone or in combination with ERT or other treatment modalities.