GASTRIC HISTOPATHOLOGY CORE A SUMMARY The primary mission of the Gastric Histopathology Core is to provide all Projects with high-quality histopathologic characterization and quality assurance of tissues from rodent models of gastric inflammation and neoplasia, immunohistochemistry (IHC) services with expert interpretation by experienced gastrointestinal pathologists, access to human gastric tissues and tissue microarray services, quantitative analysis of histologic, immunohistochemical and immunofluorescence staining of tissue sections and tissue microarrays, and large- scale digital archiving through collaboration with Dr. M. Blanca Piazuelo and Dr. Kay Washington. The following services are proposed: 1. To provide expert evaluation of histopathology of rodent models of H. pylori-induced gastric neoplasia and correlation with human disease. 2. To provide priority access to custom high-quality, cost-effective research histology services, including immunohistochemistry, multiplex immunostaining, and digital histomorphology. 3. To provide custom tissue microarray services and access to human gastric tissue samples with pathologic annotation and clinical outcome. The three component Projects and Core B (Proteomics and Metabolomics Core) of this Program Project Grant all rely heavily upon morphologic analysis of gastric tissues isolated from rodent models of Helicobacter pylori-induced gastritis and gastric neoplasia. Dr. Piazuelo’s and Dr. Washington’s high level of expertise in interpretation of histopathologic changes in rodent models and in human tissues, as well as in interpretation of immunohistochemical studies, will be critical to this work, and these collaborative activities are currently not funded through existing resources. By utilizing the resources of a GI research-related immunohistochemistry facility, it will be possible to achieve high standards for all histologic studies proposed in this grant. This centralization of histologic services under the supervision of experienced pathologists with a dedicated interest in gastrointestinal pathology will also allow careful attention to quality assurance. In addition, the access to human gastric tissues allows each Project the ability to quickly translate findings in H. pylori-infected rodent models of gastric inflammation and cancer to human disease along the cascade from non-atrophic gastritis to intestinal metaplasia, and cancer. Core A will continue to collaborate with Core B by coordinating tissue annotation for imaging mass spectrometry. Core A will also work synergistically with Core B by using IHC to localize protein targets and validate expression changes identified by proteomics analysis and enzymes implicated by metabolomics studies.