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Background: Hyperuricemia drives the development of nonalcoholic fatty liver disease (NAFLD). Pharmacological inhibition of xanthine oxidase (XO), a rate-limiting enzyme for uric acid (UA) production, has been demonstrated to improve hepatic steatosis in diet-induced obese mice. However, it remains unclear whether inhibition of XO could improve nonalcoholic steatohepatitis (NASH), a more advanced form of NAFLD, in terms of both liver inflammation and fibrosis. Methods: To investigate the effects of febuxostat and allopurinol, XO inhibitors clinically used for gout, on diet-induced NASH, C57BL/6J mice were fed a high-fat, high-cholesterol, and cholate diet (CL diet) with or without either 0.001% febuxostat or 0.003% allopurinol for 18 weeks. Systemic glucose tolerance and insulin sensitivity, liver histology, inflammation, and oxidative stress were tested. Furthermore, we conducted a single-arm, open-label intervention study with febuxostat for NAFLD patients with hyperuricemia. Findings: Despite a similar hypouricemic effect of the XO inhibitors on blood UA level, febuxostat, but not allopurinol, significantly decreased hepatic UA levels in CL diet-fed mice. This reduction in hepatic UA levels was accompanied by alleviated insulin resistance, lipid peroxidation, and classically activated M1-like macrophage accumulation in the liver. Furthermore, in NAFLD patients with hyperuricemia, treatment with febuxostat for 24 weeks decreased the serum UA level, accompanied by a reduction in serum levels of liver enzymes, alanine aminotransferase and aspartate aminotransferase. Interpretation: XO may represent a promising therapeutic target in NAFLD/NASH, especially in patients with hyperuricemia. Trial Registration: The study has been registered with UMIN-CTR (#UMIN000008686). Funding Statement: This work was supported by Grants-in-aid for Scientific Research (B) (25282017) and Challenging Exploratory Research (15K12698) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan and the Japan Diabetes Foundation (to T.O.). This study was also supported by Teijin Pharma Limited. Declaration of Interests: The authors declare no conflict of interest associated with this manuscript. Ethics Approval Statement: The study was approved by the Ethics Committee of Kanazawa University Hospital. All animal procedures were performed in accordance with the Guidelines for the Care and Use of Laboratory Animals of Kanazawa University, Japan.

Glycemic control is important for diabetic retinopathy (DR), but not sufficient for the inhibition after proliferative DR (PDR). Uric acid in the vitreous is reportedly increased in patients with DR, especially in the PDR. Here, the involvement of xanthine oxidoreductase (XO), responsible for uric acid production, in worsening DR was examined in both mouse model and co-cultured angiogenesis model. First, retinal pericytes were abolished by anti-PDGFRβ antibody injection to C57/Bl6 neonatal mouse at P1. Pericyte dropout from endothelial cells is reportedly early histological change in DR, and induces bleeding, abnormal angiogenesis, inflammation, and retinal detachment with rapid progression at P9-11. The expression of XO level in retina was increasing after pericyte breakdown, and was proportional to VEGF, and preceding the increase of TNFalpha. When 3.6mg/kg Febuxostat (Fbx), an XO inhibitor was injected at P7, widespread edema and retinal detachment/funnel-like deformation were dramatically improved by Fbx treatment at P11. ICAM-1+ cells surrounding edema and CD11b+ cells were reduced. Next, we performed a 3D culture sprouting assay using HUVEC spheroids in collagen gel co-cultured with human lung fibroblast (hLF) in fibrin gel. By Fbx treatment within the physiological concentration, the branch sprouting, cellular migration to the distal side and mitosis in branch stems were inhibited. ICAM-1 increase in HUVEC was observed with hLF co-culture but was suppressed by Fbx treatment. Finally, these effects of Fbx were not shown on HUVEC in planar culture. On the other hand, dissolution of fibrin by hLF was delayed directly due to Fbx. VEGF and PAI-1 expression from hLF and MMP-9 activity in medium were decreased by Fbx treatment. In summary, XO inhibition improved retinal inflammation and injury after pericyte loss. These results suggest the role of humoral inflammatory factors from mesenchymal cells surrounding retinal vessels in the hyperpermeable state such as DR. Disclosure A. Kushiyama: Research Support; Self; Teijin Pharma Limited, Sanwa Kagaku Kenkyusho Co., Ltd., Kowa Pharmaceutical Co., Ltd, StaGen. Consultant; Self; RIZAP. T. Kikuchi: None. H. Yamazaki: None. T. Yamamotoya: None. H. Sakoda: None. M. Fujishiro: Research Support; Self; Johnson & Johnson Services, Inc.. Y. Nakatsu: None. A. Uemura: Research Support; Self; Daiichi Sankyo Company, Limited, Boehringer Ingelheim GmbH, KAN Research Institute, Inc. T. Shirakura: Employee; Self; Teijin Pharma Limited. T. Asano: Research Support; Self; Teijin Pharma Limited, Sanwa Kagaku Kenkyusho Co., Ltd., Sanofi K.K. Y. Iwamoto: Board Member; Self; Japan Diabetes Foundation.

Oxidative stress and mitochondrial dysfunction are important determinants of neurodegeneration in secondary progressive multiple sclerosis (SPMS). We previously showed that febuxostat, a xanthine oxidase inhibitor, ameliorated both relapsing-remitting and secondary progressive experimental autoimmune encephalomyelitis (EAE) by preventing neurodegeneration in mice. In this study, we investigated how febuxostat protects neuron in secondary progressive EAE. A DNA microarray analysis revealed that febuxostat treatment increased the CNS expression of several mitochondria-related genes in EAE mice, most notably including GOT2, which encodes glutamate oxaloacetate transaminase 2 (GOT2). GOT2 is a mitochondrial enzyme that oxidizes glutamate to produce α-ketoglutarate for the Krebs cycle, eventually leading to the production of adenosine triphosphate (ATP). Whereas GOT2 expression was decreased in the spinal cord during the chronic progressive phase of EAE, febuxostat-treated EAE mice showed increased GOT2 expression. Moreover, febuxostat treatment of Neuro2a cells in vitro ameliorated ATP exhaustion induced by rotenone application. The ability of febuxostat to preserve ATP production in the presence of rotenone was significantly reduced by GOT2 siRNA. GOT2-mediated ATP synthesis may be a pivotal mechanism underlying the protective effect of febuxostat against neurodegeneration in EAE. Accordingly, febuxostat may also have clinical utility as a disease-modifying drug in SPMS.

Several lines of epidemiological evidence have suggested that non-alcoholic steatohepatitis (NASH) is closely associated with obesity in humans. However, the precise mechanisms of the progression of NASH and its key metabolic abnormalities remain to be elucidated. We found that long-term high-fat diet (HFD) exposure induces NASH, with excess body weight, hyperinsulinemia and hypercholesteremia in mice. Longitudinal analysis of the model showed that steatohepatitis was induced after onset of metabolic abnormalities. In addition, we found that expression of MCP-1 mRNA was induced in the liver before induction of TNFalpha and type I collagen alpha1 mRNAs, and prior to onset of steatohepatitis. We confirmed that hepatic MCP-1 contents were increased in mice fed HFD for 50 weeks, although the precise role of MCP-1 in the development of NASH remains to be addressed. The mouse model was also characterized by moderate reductions in catalase activity and glutathione content, as well as by overexpression of fatty acid synthase, acetyl-CoA carboxylase 1 and FAT/CD36 mRNAs in the liver. The murine NASH model apparently mimics clinical aspects of the condition and provides insight into NASH.

Objective: Atherosclerosis is a chronic inflammatory disease of the vascular wall. Multiple mechanisms are implicated in the inflammatory process, including oxidative stress. Xanthine oxidase (XO), which is converted from xanthine dehydrogenase (XDH), is a major enzymatic source of reactive oxygen species (ROS) and has been reported to be involved in atherosclerosis, but the underlying mechanisms remain unclear. We have examined whether XO contributes to atherosclerosis in mice and whether XO mediates cholesterol crystal (CC)-induced inflammation. Approach and Results: ApoE -/- mice fed a high cholesterol diet for 12 weeks (ApoE -/- ) developed atherosclerotic plaques, increased ROS generation, increased tissue activities of XO/XDH, and endothelial dysfunction. Immunohistochemical analysis revealed that XO/XDH were increased in macrophages in atherosclerotic plaques and in aortic endothelial cells. Febuxostat, a highly potent XO/XDH inhibitor, significantly attenuated plaque formation, decreased ROS generation, and improved endothelial dysfunction in ApoE -/- mice without affecting plasma cholesterol levels. Additionally, in aorta from febuxostat-treated group, MCP-1 mRNA was significantly decreased whereas eNOS mRNA was increased. Furthermore, we examined the effects of febuxostat on CC-induced inflammation in macrophages. Febuxostat significantly inhibited CC-induced ROS formation as well as MCP-1, IL-1α, IL-1β and IL-6 production and its effects could be recapitulated by ROS scavengers. Conclusions: These results demonstrated that increased XO leads to ROS formation and contributes to the progression of atherosclerosis via endothelial dysfunction and macrophage inflammation, and that febuxostat may be a potential therapeutic agent to target inflammation in atherosclerosis.

Atherosclerosis is a chronic inflammatory disease due to lipid deposition in the arterial wall. Multiple mechanisms participate in the inflammatory process, including oxidative stress. Xanthine oxidase (XO) is a major source of reactive oxygen species (ROS) and has been linked to the pathogenesis of atherosclerosis, but the underlying mechanisms remain unclear. Here, we show enhanced XO expression in macrophages in the atherosclerotic plaque and in aortic endothelial cells in ApoE−/− mice and that febuxostat, a highly potent XO inhibitor, suppressed plaque formation, reduced arterial ROS levels and improved endothelial dysfunction in ApoE−/− mice without affecting plasma cholesterol levels. In vitro, febuxostat inhibited cholesterol crystal-induced ROS formation and inflammatory cytokine release in murine macrophages. These results demonstrate that in the atherosclerotic plaque, XO-mediated ROS formation is pro-inflammatory and XO-inhibition by febuxostat is a potential therapy for atherosclerosis.

Obesity is often accompanied by hyperuricemia. However, purine metabolism in various tissues, especially regarding uric acid production, has not been fully elucidated. Here we report, using mouse models, that adipose tissue could produce and secrete uric acid through xanthine oxidoreductase (XOR) and that the production was enhanced in obesity. Plasma uric acid was elevated in obese mice and attenuated by administration of the XOR inhibitor febuxostat. Adipose tissue was one of major organs that had abundant expression and activities of XOR, and adipose tissues in obese mice had higher XOR activities than those in control mice. 3T3-L1 and mouse primary mature adipocytes produced and secreted uric acid into culture medium. The secretion was inhibited by febuxostat in a dose-dependent manner or by gene knockdown of XOR. Surgical ischemia in adipose tissue increased local uric acid production and secretion via XOR, with a subsequent increase in circulating uric acid levels. Uric acid secretion from whole adipose tissue was increased in obese mice, and uric acid secretion from 3T3-L1 adipocytes was increased under hypoxia. Our results suggest that purine catabolism in adipose tissue could be enhanced in obesity. Background: Purine metabolism in adipose tissue is largely unknown. Results: Adipose tissue has abundant xanthine oxidoreductase activity. Uric acid is secreted from adipose tissues and cells, and the secretion is augmented in obese mice. Conclusion: Adipose tissue can secrete uric acid in mice. Significance: Dysfunction of obese adipose tissue could be related to overproduction of uric acid.

Objectives Oxidative stress plays an important role in the pathogenesis of multiple sclerosis (MS). Though reactive oxygen species (ROS) are produced by various mechanisms, xanthine oxidase (XO) is a major enzyme generating ROS in the context of inflammation. The objectives of this study were to investigate the involvement of XO in the pathogenesis of MS and to develop a potent new therapy for MS based on the inhibition of ROS. Methods XO were assessed in a model of MS: experimental autoimmune encephalomyelitis (EAE). The contribution of XO-generated ROS to the pathogenesis of EAE was assessed by treating EAE mice with a novel XO inhibitor, febuxostat. The efficacy of febuxostat was also examined in in vitro studies. Results We showed for the first time that the expression and the activity of XO were increased dramatically within the central nervous system of EAE mice as compared to naive mice. Furthermore, prophylactic administration of febuxostat, a XO inhibitor, markedly reduced the clinical signs of EAE. Both in vivo and in vitro studies showed infiltrating macrophages and microglia as the major sources of excess XO production, and febuxostat significantly suppressed ROS generation from these cells. Inflammatory cellular infiltration and glial activation in the spinal cord of EAE mice were inhibited by the treatment with febuxostat. Importantly, therapeutic efficacy was observed not only in mice with relapsing-remitting EAE but also in mice with secondary progressive EAE by preventing axonal loss and demyelination. Conclusion These results highlight the implication of XO in EAE pathogenesis and suggest XO as a target for MS treatment and febuxostat as a promising therapeutic option for MS neuropathology.

Glucose ingestion stimulates the secretion of the incretin hormones, glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1). Despite the critical role of incretins in glucose homeostasis, the mechanism of glucose-induced incretin secretion has not been established. We investigated the underlying mechanism of glucose-induced incretin secretion in vivo in mice. Injection of glucose at 1 g/kg in the upper intestine significantly increased plasma GIP and GLP-1 levels, whereas injection of glucose in the colon did not increase GIP or GLP-1 levels. This finding indicates that the glucose sensor for glucose-induced incretin secretion is in the upper intestine. Coadministration of a sodium-glucose cotransporter-1 (SGLT1) inhibitor, phloridzin, with glucose in the upper intestine blocked glucose absorption and glucose-induced incretin secretion. α-methyl-d-glucopyranoside (MDG), an SGLT1 substrate that is a nonmetabolizable sugar, significantly increased plasma GIP and GLP-1 levels, whereas phloridzin blocked these increases, indicating that concomitant transport of sodium ions and glucose (substrate) via SGLT1 itself triggers incretin secretion without the need for subsequent glucose metabolism. Interestingly, oral administration of MDG significantly increased plasma GIP, GLP-1, and insulin levels and reduced blood glucose levels during an intraperitoneal glucose tolerance test. Furthermore, chronic MDG treatment in drinking water (3%) for 13 days reduced blood glucose levels after a 2-h fast and in an oral glucose tolerance test in diabetic db/db mice. Our findings indicate that SGLT1 serves as the intestinal glucose sensor for glucose-induced incretin secretion and that a noncalorigenic SGLT1 substrate ameliorates hyperglycemia by stimulating incretin secretion.

Peptide YY (PYY)(3-36), a neuropeptide Y (NPY) Y2 receptor agonist, is a powerful inhibitor of intestinal secretion. Based on this anti-secretory effect, NPY Y2 receptor agonists may be useful as novel anti-diarrheal agents, but anti-diarrheal efficacy has yet to be determined. We therefore examined the anti-diarrheal efficacy of PYY(3-36) and a selective Y2 receptor agonist, N-acetyl-[Leu28, Leu31]-NPY(24-36), in experimental mouse models of diarrhea. Intraperitoneal administration of PYY(3-36) (0.01-1mg/kg) and N-acetyl-[Leu28, Leu31]-NPY(24-36) (10mg/kg) significantly inhibited diarrhea (increase in wet fecal weight and diarrhea score) induced by dimethyl-prostaglandin E2, 5-hydroxytryptamine, and castor oil. Anti-diarrheal activities of PYY(3-36) and N-acetyl-[Leu28, Leu31]-NPY(24-36) were comparable to the effects of loperamide (1mg/kg), a widely used anti-diarrheal drug. To clarify the anti-diarrheal mechanisms of NPY Y2 receptor agonists, we investigated the effects of PYY(3-36) and N-acetyl-[Leu28, Leu31]-NPY(24-36) on intestinal fluid secretion and colonic transit. PYY(3-36) (1mg/kg) and N-acetyl-[Leu28, Leu31]-NPY(24-36) (10mg/kg) significantly reduced dimethyl-prostaglandin E2-induced intestinal fluid accumulation in conscious mice, suggesting that NPY Y2 receptor agonists inhibit diarrhea, at least in part, by reducing intestinal secretion. In addition, PYY(3-36) (0.01-1mg/kg) and N-acetyl-[Leu28, Leu31]-NPY(24-36) (10mg/kg) potently inhibited normal fecal output, suggesting that NPY Y2 receptor activation inhibits colonic motor function and NPY Y2 receptor agonists inhibit diarrhea partly by slowing colonic transit. These results indicate that NPY Y2 receptor agonists inhibit diarrhea in mice by not only reducing intestinal fluid secretion, but also slowing colonic transit, and illustrate the therapeutic potential of NPY Y2 receptor agonists as effective treatments for diarrhea.

Pancreatic polypeptide is released mainly from the pancreas, and is thought to be one of the major endogenous agonists of the neuropeptide Y Y4 receptor. Pancreatic polypeptide has been shown to stimulate colonic muscle contraction, but whether pancreatic polypeptide has in vivo functional activity with respect to colonic transit is unclear. The present report investigated the effects of pancreatic polypeptide on fecal output as an index of colonic transit as well as intestinal motor activity, using wild-type (WT) and neuropeptide Y Y4 receptor-deficient (KO) mice. Peripheral administration of pancreatic polypeptide increased fecal weight and caused diarrhea in WT mice in a dose-dependent manner (0.01–3 mg/kg s.c.). Pancreatic polypeptide-induced increases in fecal weight and diarrhea completely disappeared in KO mice, while basal fecal weights did not differ between WT and KO mice. In longitudinal and circular muscles of mouse isolated colon, pancreatic polypeptide (0.01–1 μM) increased basal tone and frequency of spontaneous contraction in WT mice, but not in KO mice. Atropine did not affect pancreatic polypeptide-induced fecal output or increase in colonic muscle tone, indicating that the actions of pancreatic polypeptide are not mediated through cholinergic mechanisms. The present findings demonstrate that pancreatic polypeptide enhances colonic contractile activity and fecal output through neuropeptide Y Y4 receptor, and a neuropeptide Y Y4 receptor agonist might offer a novel therapeutic approach to ameliorate constipation.

Microsphere embolism (ME)-induced ischemia model in rat resembles to multiple brain embolism in human with several clinical features. We here tested whether nitric oxide (NO) production contributes to the neuronal injury in the ME model. A novel calmodulin antagonist, DY-9760e, having a potent inhibitory effect on neuronal nitric oxide synthase (nNOS), reduced brain infarct size in the ME-induced brain ischemia. Consistent with our previous observation with gerbil ischemia/reperfusion model, DY-9760e completely inhibited NO production immediately after and 24 or 48 h after ME. Unlike the gerbil ischemia/reperfusion model, protein tyrosine nitration markedly increased 6-48 h after ME. DY-9760e treatment completely inhibited the marked increase in the protein tyrosine nitration at 24 h after ME. These results suggest that the inhibition of NO production and protein tyrosine nitration by DY-9760e contribute to its neuroprotective action in the ME-induced brain damage.

devastating consequences, and others with little or no overt pathology. Adoptive immunotherapy is an approach that involves administration of anti-viral T cells and has shown promise in clinical studies for the treatment of cytomegalovirus, Epstein–Barr virus, and adenovirus infections. We model adoptive immunotherapy by transferring antiviral memory T cells into mice persistently infected from birth with lymphocytic choriomeningitis virus. Here, we demonstrate thatmemory T cells can completely purge the brain of persistently infected mice without causing blood brain barrier breakdown or tissue damage. This is accomplished by a tailored release of chemoattractants that recruit antiviral T cells, but few pathogenic innate immune cells such as neutrophils and inflammatorymonocytes. Interestingly, T cells enlist the support of nearly all brain resident myeloid cells (microglia) by converting them into CD11c-expressing antigen-presenting cells (APCs)— a cell population also found in the brain of a patient infected with human immunodeficiency virus. Two-photon imaging studies revealed that anti-viral CD8 T cells are more likely to decelerate and form stable interactions with brain-resident APCs than CD4 T cells. Importantly, CD11c microglia are resistant to apoptosis and do not undergo cell death following T cell engagement.We propose that non-cytopathic CNS viral clearance can be achieved by therapeutic memory T cells reliant on tailored chemoattractant production and interactions with resident myeloid cells.

Xanthine oxidase (XO) is an enzyme responsible for the production of uric acid. XO produces considerable amount of oxidative stress throughout the body. To date, however, its pathophysiologic role in hypertension and endothelial dysfunction still remains controversial. To explore the possible involvement of XO-derived oxidative stress in the pathophysiology of vascular dysfunction, by use of a selective XO inhibitor, febuxostat, we investigated the impact of pharmacological inhibition of XO on hypertension and vascular endothelial dysfunction in spontaneously hypertensive rats (SHRs). Sixteen-week-old SHR and normotensive Wistar-Kyoto (WKY) rats were treated with tap water (control) or water containing febuxostat (3 mg/kg/day) for 6 weeks. Systolic blood pressure (SBP) in febuxostat-treated SHR (220 ± 3 mmHg) was significantly (P