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Abstract Chronic visceral pain disorders, such as interstitial cystitis/bladder pain syndrome (IC/BPS), are difficult to treat, and therapies are limited in number and efficacy. Emerging evidence suggests that alterations in the enzyme purine nucleoside phosphorylase (PNPase) may participate in oxidative injury and cellular damage. PNPase is important for the metabolism of ‘tissue-protective’ purine metabolites to ‘tissue-damaging’ purines that generate free radicals. The aim of this study is to test whether patients living with IC/BPS without or with Hunner lesions and irrespective of any therapies exhibit purine dysregulation with higher levels of tissue-damaging purine metabolites as measured by liquid chromatography-tandem mass spectrometry. Our results demonstrate that levels of urotoxic purine metabolites (hypoxanthine and xanthine) in IC/BPS patients with and without Hunner lesions are elevated compared to healthy controls. These findings suggest there may be pathophysiologic commonalities between patient subtypes. Furthermore, the accumulation of uroprotective purines and depletion of urodamaging purines by PNPase inhibition may be therapeutically effective in both groups of patients.

Abstract Interstitial cystitis/bladder pain syndrome (IC/BPS) is a disorder characterized by bladder pain upon filling which severely affects quality of life. Clinical presentation can vary. Local inflammatory events typify the clinical presentation of IC/BPS patients with Hunner lesions (IC/BPS-HL). It has previously been proposed that B cells are more prevalent in HL, but understanding their exact role in this environment requires a more complete immunological profile of HL. We characterized immunological dysfunction specifically in HL using immunohistochemistry. We detected significantly more plasma cells (50× increase, p

Neuromyelitis optica spectrum disorders (NMOSD) are rare, debilitating autoimmune diseases of the central nervous system. Many NMOSD patients have antibodies to Aquaporin-4 (AQP4). Prior studies show associations of NMOSD with individual Human Leukocyte Antigen (HLA) alleles and with mutations in the complement pathway and potassium channels. HLA allele associations with NMOSD are inconsistent between populations, suggesting complex relationships between the identified alleles and risk of disease. We used a retrospective case-control approach to identify contributing genetic variants in patients who met the diagnostic criteria for NMOSD and their unaffected family members. Potentially deleterious variants identified in NMOSD patients were compared to members of their families who do not have the disease and to existing databases of human genetic variation. HLA sequences from patients from Belgrade, Serbia, were compared to the frequency of HLA haplotypes in the general population in Belgrade. We analyzed exome sequencing on 40 NMOSD patients and identified rare inherited variants in the complement pathway and potassium channel genes. Haplotype analysis further detected two haplotypes, HLA-A*01, B*08, DRB1*03 and HLA-A*01, B*08, C*07, DRB1*03, DQB1*02, which were more prevalent in NMOSD patients than in unaffected individuals. In silico modeling indicates that HLA molecules within these haplotypes are predicted to bind AQP4 at several sites, potentially contributing to the development of autoimmunity. Our results point to possible autoimmune and neurodegenerative mechanisms that cause NMOSD, and can be used to investigate potential NMOSD drug targets.