Despite superb efforts of patient advocacy groups, our insight into the etiology, diagnosis and treatment for interstitial cystitis (IC) is still inadequate. Since the luminal glycosaminoglycan (GAG) layer protects the bladder urothelium from noxious substances in urine, alterations in urothelial GAGs may be associated with IC pathophysiology. Urinary levels of total (i.e., non-sulfated and sulfated) GAGs and hyaluronic acid (HA) are elevated in IC patients with severe disease, as judged by the validated O'Leary-Sant questionnaire and clinical index. These patients' urine also contain one or more unique GAG species and a high molecular mass HA species. Urinary total GAG levels and GAG profile appear to be accurate markers for monitoring disease severity, regardless of the type of treatment the patients are undergoing. IC urothelial cultures secrete higher levels of matrix metalloproteinases (MMPs)-2 and -9, when compared with normal urothelial cells, suggesting an association between MMPs and this disease. This proposal is designed to investigate the involvement of IC specific GAGs, high molecular mass HA and MMPs in the pathophysiology of IC and how GAG-like substances may bring about symptom relief. Furthermore, to evaluate in a multi-center trial the usefulness of total urinary GAG and HA levels, GAG and HA profiles and urinary MMP levels in the follow-up of IC patients. To identify IC-specific GAGs and their cellular source, these GAGs will be purified from IC patients' urine and primary urothelial culture conditioned media (CM), by sequential liquid chromatographies, digestion with GAG-degrading enzymes and HPLC (Aim 1). The cellular basis of qualitative and quantitative alterations in GAGs, will be evaluated by performing a pair-wise comparison of GAG levels and GAG profile in urine, tissue extracts and urothelial CM from IC patients with varying degrees of disease severity. The involvement of IC-specific GAGs in IC pathophysiology and of GAG-like substances in causing symptom relief, will be evaluated by cDNA microarray analysis of changes in gene expression in normal and IC urothelial cells treated with IC-specific GAGs and pentosan polysulfate, respectively (Aim 2). To understand their association with IC, HA levels; HA profile and MMP levels will be analyzed in urine, tissue extracts and urothelial CM from IC patients with varying degrees of disease severity. Changes in normal urothelial gene expression following treatment with high molecular mass HA will be evaluated by cDNA microarray analysis, and compared with gene expression in IC urothelial cells, to reveal the involvement of HA in IC pathophysiology (Aim 3). In a multi-center trial, the usefulness of total GAG levels, GAG and HA profile and MMP levels in IC patient follow-up and their use for monitoring treatment response will be evaluated (Aim 4). The proposed study will reveal the function and diagnostic potential of urothelial GAGs (including HA) and MMPs in 1C pathophysiology. Furthermore, it might yield a test or a combination of tests that can be used in the follow-up of IC patients and for monitoring 9 treatment responses.