Granulomas are dynamic, focal, tissue-destructive inflammatory reactions. They can lead to extensive organ damage as seen in Crohn's disease, schistosomiasis and sarcoidosis. Intricate immunoregulatory events occur within a granulomatous response. Murine schistosomiasis is an excellent model in which to study granuloma regulation. In murine schistosomiasis, it is probable that inflammatory cells within the liver granulomas secrete neuropeptides (see appendix). Studies of liver granulomas have failed to demonstrate nerves within these lesions supporting the conclusion that the origins of liver granuloma neuropeptides are the inflammatory cells. The premise of this proposal is that neuropeptides are produced by and released from granuloma inflammatory cells. Once released, they serve s immunoregulatory molecules in granulomatous responses of the liver and intestines through interaction with specific hormone receptors on subsets of other inflammatory cells, perturbing their function. This study will focus on vasoactive intestinal polypeptide (VIP), substance P (SP) and somatostatin, since data suggest that these neuropeptides may function in immunoregulation and each has been detected within these granulomas by our laboratory. The following are the specific objectives. 1. The authenticity of granuloma immunoreactive VIP, SP and somatostatin will be validated and their sites of storage/gene expression localized within intact granulomas and inflammatory cells isolated from granulomas employing radioimmunoassay, HPLC elution, amino acid analysis, Northern blot analysis, immunohistochemistry, and oligonucleotide and/or cDNA hybridization. 2. Additional experiments will determine whether granuloma inflammatory cells synthesize/release neuropeptides and characterize mechanisms by which these activities are modulated utilizing cell culture techniques, the reverse hemolytic plaque assay and other techniques listed above. 3. In order to determine the cells targeted for neuropeptide action, receptors for these neuropeptides will be characterized on subsets of granuloma inflammatory cells utilizing radio-, fluorescent- and in situ- binding assays. 4. Mechanisms will then be identified by which these neuropeptides alter inflammatory cell function within the granuloma. Understanding the processes involved in the immunoregulation of granulomatous responses may permit the development of improved therapeutic modalities.
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