In Vivo Characterization of a Novel γ-Secretase Inhibitor SCH 697466 in Rodents and Investigation of Strategies for Managing Notch-Related Side Effects.

Substantial evidence implicates ß-amyloid (Aß) peptides in the etiology of Alzheimer's disease (AD). Aß is produced by the proteolytic cleavage of the amyloid precursor protein by ß- and γ-secretase suggesting that γ-secretase inhibition may provide therapeutic benefit for AD. Although many γ-secretase inhibitors have been shown to be potent at lowering Aß, some have also been shown to have side effects following repeated administration. All of these side effects can be attributed to altered Notch signaling, another γ-secretase substrate. Here we describe the in vivo characterization of the novel γ-secretase inhibitor SCH 697466 in rodents. Although SCH 697466 was effective at lowering Aß, Notch-related side effects in the intestine and thymus were observed following subchronic administration at doses that provided sustained and complete lowering of Aß. However, additional studies revealed that both partial but sustained lowering of Aßand complete but less sustained lowering of Aß were successful approaches for managing Notch-related side effects. Further, changes in several Notch-related biomarkers paralleled the side effect observations. Taken together, these studies demonstrated that, by carefully varying the extent and duration of Aß lowering by γ-secretase inhibitors, it is possible to obtain robust and sustained lowering of Aß without evidence of Notch-related side effects.

Small conformationally restricted piperidine N-arylsulfonamides as orally active gamma-secretase inhibitors.

The design and development of a new class of small 2,6-disubstituted piperidine N-arylsulfonamide gamma-secretase inhibitors is reported. Lowering molecular weight including the use of conformational constraint led to compounds with less CYP 3A4 liability compared to early leads. Compounds active orally in lowering Abeta levels in Tg CRND8 mice were identified as potential treatments for Alzheimer's disease.

Advancing translational research with the Semantic Web.

BACKGROUND: A fundamental goal of the U.S. National Institute of Health (NIH) "Roadmap" is to strengthen Translational Research, defined as the movement of discoveries in basic research to application at the clinical level. A significant barrier to translational research is the lack of uniformly structured data across related biomedical domains. The Semantic Web is an extension of the current Web that enables navigation and meaningful use of digital resources by automatic processes. It is based on common formats that support aggregation and integration of data drawn from diverse sources. A variety of technologies have been built on this foundation that, together, support identifying, representing, and reasoning across a wide range of biomedical data. The Semantic Web Health Care and Life Sciences Interest Group (HCLSIG), set up within the framework of the World Wide Web Consortium, was launched to explore the application of these technologies in a variety of areas. Subgroups focus on making biomedical data available in RDF, working with biomedical ontologies, prototyping clinical decision support systems, working on drug safety and efficacy communication, and supporting disease researchers navigating and annotating the large amount of potentially relevant literature. RESULTS: We present a scenario that shows the value of the information environment the Semantic Web can support for aiding neuroscience researchers. We then report on several projects by members of the HCLSIG, in the process illustrating the range of Semantic Web technologies that have applications in areas of biomedicine. CONCLUSION: Semantic Web technologies present both promise and challenges. Current tools and standards are already adequate to implement components of the bench-to-bedside vision. On the other hand, these technologies are young. Gaps in standards and implementations still exist and adoption is limited by typical problems with early technology, such as the need for a critical mass of practitioners and installed base, and growing pains as the technology is scaled up. Still, the potential of interoperable knowledge sources for biomedicine, at the scale of the World Wide Web, merits continued work.

AlzPharm: integration of neurodegeneration data using RDF.

BACKGROUND: Neuroscientists often need to access a wide range of data sets distributed over the Internet. These data sets, however, are typically neither integrated nor interoperable, resulting in a barrier to answering complex neuroscience research questions. Domain ontologies can enable the querying heterogeneous data sets, but they are not sufficient for neuroscience since the data of interest commonly span multiple research domains. To this end, e-Neuroscience seeks to provide an integrated platform for neuroscientists to discover new knowledge through seamless integration of the very diverse types of neuroscience data. Here we present a Semantic Web approach to building this e-Neuroscience framework by using the Resource Description Framework (RDF) and its vocabulary description language, RDF Schema (RDFS), as a standard data model to facilitate both representation and integration of the data. RESULTS: We have constructed a pilot ontology for BrainPharm (a subset of SenseLab) using RDFS and then converted a subset of the BrainPharm data into RDF according to the ontological structure. We have also integrated the converted BrainPharm data with existing RDF hypothesis and publication data from a pilot version of SWAN (Semantic Web Applications in Neuromedicine). Our implementation uses the RDF Data Model in Oracle Database 10g release 2 for data integration, query, and inference, while our Web interface allows users to query the data and retrieve the results in a convenient fashion. CONCLUSION: Accessing and integrating biomedical data which cuts across multiple disciplines will be increasingly indispensable and beneficial to neuroscience researchers. The Semantic Web approach we undertook has demonstrated a promising way to semantically integrate data sets created independently. It also shows how advanced queries and inferences can be performed over the integrated data, which are hard to achieve using traditional data integration approaches. Our pilot results suggest that our Semantic Web approach is suitable for realizing e-Neuroscience and generic enough to be applied in other biomedical fields.

Discovery of gamma-secretase inhibitors efficacious in a transgenic animal model of Alzheimer's disease.

Attachment of the cyclopropylcarbamate group to the piperidine core of gamma-secretase inhibitors leads to a dramatic increase of their in vitro potency. Strategies for subsequent improvement of the in vivo pharmacokinetic profile of the series are discussed. Resulting compounds significantly reduce Abeta levels in TgCRND8 mice after a single PO dosing at 30 mpk.

Age-progressing cognitive impairments and neuropathology in transgenic CRND8 mice.

Patients with Alzheimer's disease suffer from progressive cognitive impairments and show distinct post-mortem neuropathology, including beta-amyloid plaques. Transgenic (Tg) CRND8 mice carry a mutated human amyloid precursor protein gene and show age-related increases in beta-amyloid production and plaque deposition. It was previously reported that during the early stages of plaque deposition, Tg CRND8 mice demonstrated Morris maze impairments. However, it is unknown if Tg mice would be impaired at an earlier age prior to plaque deposition or more impaired at a later age with more extensive plaque deposition. In the current study, we describe Tg CRND8 age-progressing beta-amyloid neuropathology and cognitive abilities in greater detail. At all ages, Tg mice showed normal short-term memory in the Y-maze. Pre-plaque Tg and age-matched Non-Tg mice did not differ in learning the spatial Morris water maze. However, both early and late plaque Tg mice showed impairments during acquisition. In addition, although early plaque Tg mice performed well in the probe trial, late plaque Tg mice demonstrated impaired probe trial performance. Therefore compared to their Non-Tg littermates, Tg CRND8 mice demonstrate cognitive impairments that progressed with age and seemed to coincide with the onset of beta-amyloid plaque deposition.

Abnormality of G-protein-coupled receptor kinases at prodromal and early stages of Alzheimer's disease: an association with early beta-amyloid accumulation.

Overwhelming evidence indicates that the effects of beta-amyloid (Abeta) are dose dependent both in vitro and in vivo, which implies that Abeta is not directly detrimental to brain cells until it reaches a threshold concentration. In an effort to understand early Alzheimer's disease (AD) pathogenesis, this study focused on the effects of subthreshold soluble Abeta and the underlying molecular mechanisms in murine microglial cells and an AD transgenic mouse model. We found that there were two phases of dose-dependent Abeta effects on microglial cells: at the threshold of 5 microm and above, Abeta directly induced tumor necrosis factor-alpha (TNF-alpha) release, and at subthreshold doses, Abeta indirectly potentiated TNF-alpha release induced by certain G-protein-coupled receptor (GPCR) activators. Mechanistic studies revealed that subthreshold Abeta pretreatment in vitro reduced membrane GPCR kinase-2/5 (GRK2/5), which led to retarded GPCR desensitization, prolonged GPCR signaling, and cellular hyperactivity to GPCR agonists. Temporal analysis in an early-onset AD transgenic model, CRND8 mice, revealed that the membrane (functional) GRK2/5 in brain cortices were significantly reduced. More importantly, such a GRK abnormality took place before cognitive decline and changed in a manner corresponding with the mild to moderate soluble Abeta accumulation in these transgenic mice. Together, this study not only discovered a novel link between subthreshold Abeta and GRK dysfunction, it also demonstrated that the GRK abnormality in vivo occurs at prodromal and early stages of AD.

Chronic treatment with the gamma-secretase inhibitor LY-411,575 inhibits beta-amyloid peptide production and alters lymphopoiesis and intestinal cell differentiation.

Inhibition of gamma-secretase, one of the enzymes responsible for the cleavage of the amyloid precursor protein (APP) to produce the pathogenic beta-amyloid (Abeta) peptides, is an attractive approach to the treatment of Alzheimer disease. In addition to APP, however, several other gamma-secretase substrates have been identified (e.g. Notch), and altered processing of these substrates by gamma-secretase inhibitors could lead to unintended biological consequences. To study the in vivo consequences of gamma-secretase inhibition, the gamma-secretase inhibitor LY-411,575 was administered to C57BL/6 and TgCRND8 APP transgenic mice for 15 days. Although most tissues were unaffected, doses of LY-411,575 that inhibited Abeta production had marked effects on lymphocyte development and on the intestine. LY-411,575 decreased overall thymic cellularity and impaired intrathymic differentiation at the CD4(-)CD8(-)CD44(+)CD25(+) precursor stage. No effects on peripheral T cell populations were noted following LY-411,575 treatment, but evidence for the altered maturation of peripheral B cells was observed. In the intestine, LY-411,575 treatment increased goblet cell number and drastically altered tissue morphology. These effects of LY-411,575 were not seen in mice that were administered LY-D, a diastereoisomer of LY-411,575, which is a very weak gamma-secretase inhibitor. These studies show that inhibition of gamma-secretase has the expected benefit of reducing Abeta in a murine model of Alzheimer disease but has potentially undesirable biological effects as well, most likely because of the inhibition of Notch processing.