Xanthine Dehydrogenase Is a Modulator of Dopaminergic Neurodegeneration in Response to Bacterial Metabolite Exposure in C. elegans.

Oxidative stress is a contributing factor to Parkinson's disease (PD). Considering the prevalence of sporadic PD, environmental exposures are postulated to increase reactive oxygen species and either incite or exacerbate neurodegeneration. We previously determined that exposure to the common soil bacterium, Streptomyces venezuelae (S. ven), enhanced oxidative stress and mitochondrial dysfunction in Caenorhabditis elegans, leading to dopaminergic (DA) neurodegeneration. Here, S. ven metabolite exposure in C. elegans was followed by RNA-Seq analysis. Half of the differentially identified genes (DEGs) were associated with the transcription factor DAF-16 (FOXO), which is a key node in regulating stress response. Our DEGs were enriched for Phase I (CYP) and Phase II (UGT) detoxification genes and non-CYP Phase I enzymes associated with oxidative metabolism, including the downregulated xanthine dehydrogenase gene, xdh-1. The XDH-1 enzyme exhibits reversible interconversion to xanthine oxidase (XO) in response to calcium. S. ven metabolite exposure enhanced XO activity in C. elegans. The chelation of calcium diminishes the conversion of XDH-1 to XO and results in neuroprotection from S. ven exposure, whereas CaCl2 supplementation enhanced neurodegeneration. These results suggest a defense mechanism that delimits the pool of XDH-1 available for interconversion to XO, and associated ROS production, in response to metabolite exposure.

Xanthine dehydrogenase rewires metabolism and the survival of nutrient deprived lung adenocarcinoma cells by facilitating UPR and autophagic degradation.

Xanthine dehydrogenase (XDH) is the rate-limiting enzyme in purine catabolism by converting hypoxanthine to xanthine and xanthine to uric acid. The altered expression and activity of XDH are associated with the development and prognosis of multiple types of cancer, while its role in lung adenocarcinoma (LUAD) remains unknown. Herein, we demonstrated that XDH was highly expressed in LUAD and was significantly correlated with poor prognosis. Though inhibition of XDH displayed moderate effect on the viability of LUAD cells cultured in the complete medium, it significantly attenuated the survival of starved cells. Similar results were obtained in XDH-knockout cells. Nucleosides supplementation rescued the survival of starved LUAD cells upon XDH inhibition, while inhibition of purine nucleoside phosphorylase abrogated the process, indicating that nucleoside degradation is required for the XDH-mediated survival of LUAD cells. Accordingly, metabolic flux revealed that ribose derived from nucleoside fueled key carbon metabolic pathways to sustain the survival of starved LUAD cells. Mechanistically, down-regulation of XDH suppressed unfolded protein response (UPR) and autophagic flux in starved LUAD cells. Inhibition of XDH decreased the level of amino acids produced by autophagic degradation, which was accompanied with down-regulation of mTORC1 signaling. Supplementation of amino acids including glutamine or glutamate rescued the survival of starved LUAD cells upon knockout or inhibition of XDH. Finally, XDH inhibitors potentiated the anti-cancer activity of 2-deoxy-D-glucose that induced UPR and/or autophagy in vitro and in vivo. In summary, XDH plays a crucial role in the survival of starved LUAD cells and targeting XDH may improve the efficacy of drugs that induce UPR and autophagy in the therapy of LUAD.

Arabinogalactan and hyaluronic acid in ophthalmic solution: Experimental effect on xanthine oxidoreductase complex as key player in ocular inflammation (in vitro study).

Dry eye syndrome is a common disease associated to eyes inflammation, irritation and tear film instability. The enzymatic complex of xanthine oxidoreductase (XOR) is involved in the generation of reactive oxygen species (ROS) and uric acid that, in the end, can cause reperfusion injuries, irritation and pathological conditions. Furthermore, in the eye, it has been proposed that oxygen free radicals might play a significant role in retinal ischemic damage. A new artificial drop formulation based on arabinogalactan and hyaluronic acid has been proposed in this article. The uric acid and the ROS formation have been monitored. The effect of the arabinogalactan, the hyaluronic acid and their mixture has been studied. The arabinogalactan entails a uric acid and ROS reduction of 27% and 38% respectively; no significant reduction of uric acid or ROS has been observed after the addition of hyaluronic acid alone. Notably the combination of arabinogalactan and hyaluronic acid involves the reduction of uric acid and ROS equal to 38% and 62%, namely. This study demonstrates that this artificial drop formulation can markedly reduce the uric acid and ROS formation in vitro; thus, the use of this formulation may contribute in the resolution of the dry eye syndrome.

Febuxostat, a Xanthine Oxidoreductase Inhibitor, Decreases NLRP3-dependent Inflammation in Macrophages by Activating the Purine Salvage Pathway and Restoring Cellular Bioenergetics.

The nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome mediates caspase-1 activation and IL-1ß processing and is implicated in autoinflammatory as well as other chronic inflammatory diseases. Recent studies have demonstrated that xanthine oxidoreductase (XOR) inhibition attenuated IL-1ß secretion in activated macrophages, but the detailed mechanism of inhibition remains unclear. In this study, we report that febuxostat, an inhibitor of XOR, suppressed NLRP3 inflammasome-mediated IL-1ß secretion and cell death by two mechanisms: in a mitochondrial ROS (mitoROS)-dependent and mitoROS-independent manner. MitoROS-independent effects of febuxostat were mediated by an increase of intracellular ATP and improved mitochondrial energetics via the activation of purine salvage pathway. Our findings suggest that cellular bioenergetics are important in regulating NLRP3 activation, and XOR inhibition may be clinically relevant in NLRP3-related inflammatory diseases.

Human skeletal muscle nitrate store: influence of dietary nitrate supplementation and exercise.

KEY POINTS: Nitric oxide (NO), a potent vasodilator and a regulator of many physiological processes, is produced in mammals both enzymatically and by reduction of nitrite and nitrate ions. We have previously reported that, in rodents, skeletal muscle serves as a nitrate reservoir, with nitrate levels greatly exceeding those in blood or other internal organs, and with nitrate being reduced to NO during exercise. In the current study, we show that nitrate concentration is substantially greater in skeletal muscle than in blood and is elevated further by dietary nitrate ingestion in human volunteers. We also show that high-intensity exercise results in a reduction in the skeletal muscle nitrate store following supplementation, likely as a consequence of its reduction to nitrite and NO. We also report the presence of sialin, a nitrate transporter, and xanthine oxidoreductase in human skeletal muscle, indicating that muscle has the necessary apparatus for nitrate transport, storage and metabolism. ABSTRACT: Rodent skeletal muscle contains a large store of nitrate that can be augmented by the consumption of dietary nitrate. This muscle nitrate reservoir has been found to be an important source of nitrite and nitric oxide (NO) via its reduction by tissue xanthine oxidoreductase. To explore if this pathway is also active in human skeletal muscle during exercise, and if it is sensitive to local nitrate availability, we assessed exercise-induced changes in muscle nitrate and nitrite concentrations in young healthy humans, under baseline conditions and following dietary nitrate consumption. We found that baseline nitrate and nitrite concentrations were far higher in muscle than in plasma (∼4-fold and ∼29-fold, respectively), and that the consumption of a single bolus of dietary nitrate (12.8 mmol) significantly elevated nitrate concentration in both plasma (∼19-fold) and muscle (∼5-fold). Consistent with these observations, and with previous suggestions of active muscle nitrate transport, we present western blot data to show significant expression of the active nitrate/nitrite transporter sialin in human skeletal muscle. Furthermore, we report an exercise-induced reduction in human muscle nitrate concentration (by ∼39%), but only in the presence of an increased muscle nitrate store. Our results indicate that human skeletal muscle nitrate stores are sensitive to dietary nitrate intake and may contribute to NO generation during exercise. Together, these findings suggest that skeletal muscle plays an important role in the transport, storage and metabolism of nitrate in humans.

Pulmonary toxicity following inhalation exposure to VX in anesthetized rats: Possible roles for compromised immunity and oxidative stress-induced lung injury.

The nerve agent VX is one of the most deadly threat agents available in weapons stockpiles for intentional release. While mostly considered a percutaneous toxicant, it can be fatal when aerosolized. The objective of this study was to investigate toxic responses in the lung up to two weeks following a single 10-minute exposure to inhaled VX. Anesthetized rats were exposed singly and only once to VX. The nebulization rate in this system was 0.2-0.3 ml per minute with the delivery of a consistent particle size of 2.1 µm. Following exposure, all rats were removed from the ventilator and allowed to recover in the glovebox for 10-15 minutes. Results showed that inhaled VX altered several respiratory parameters and caused increased lung resistance up to 6 h post-exposure (PE). There was a trending increase in SOD and xanthine oxidoreductase (XOR) activities, both of which are indicative of oxidative stress. Based on increased lung tissue p38 signaling, MAP kinase expression was activated after VX exposure. IL-6 expression was also increased at 6 h post-inhalation for the 31.6 mg/m3 exposed group. Innate survival response mechanisms in rats may be present due to increased lung tissue mRNA AChE expression 6 h after exposure. Immunohistochemistry showed reduced staining for surfactant D and increased expression of iNOS, indicating that the activation of •NO precursor pathways. Bronchoalveloar lavage fluid (BALF) results from 1 h to 2 weeks PE show that inflammatory cells are highly active as evidenced by the increased production of cytokines and chemokines. This is the first study linking VX-induced lung injury to a possible innate survival amplification of AChE and possibly compromised immune function. These results could supplement medical treatment strategies with regard to therapeutic approaches against VX inhalational challenge.

Old drug, new indication: Olsalazine sodium reduced serum uric acid levels in mice via inhibiting xanthine oxidoreductase activity.

Hyperuricemia, a long-term purine metabolic disorder, is a well-known risk factor for gout, hypertension and diabetes. In maintaining normal whole-body purine levels, xanthine oxidase (XOD) is a key enzyme in the purine metabolic pathway, as it catalyzes the oxidation of hypoxanthine to xanthine and finally to uric acid. Here we used the protein-ligand docking software idock to virtually screen potential XOD inhibitors from 3167 approved small compounds/drugs. The inhibitory activities of the ten compounds with the highest scores were tested on XOD in vitro. Interestingly, all the ten compounds inhibited the activity of XOD at certain degrees. Particularly, the anti-ulcerative-colitis drug olsalazine sodium demonstrated a great inhibitory activity for XOD (IC50 = 3.4 mg/L). Enzymatic kinetic studies revealed that the drug was a hybrid-type inhibitor of xanthine oxidase. Furthermore, the drug strikingly decreased serum urate levels, serum/hepatic activities of XOD at a dose-dependent manner in vivo. Thus, we demonstrated a successful hunting process of compounds/drugs for hyperuricemia through virtual screening, supporting a potential usage of olsalazine sodium in the treatment of hyperuricemia.

SkQ1 Regulates Expression of Nrf2, ARE-Controlled Genes Encoding Antioxidant Enzymes, and Their Activity in Cerebral Cortex under Oxidative Stress.

The administration of SkQ1 to rats at the dose of 50 nmol/kg for five days significantly increased the mRNA levels of transcription factor Nrf2 and of Nrf2-controlled genes encoding antioxidant enzymes SOD1, SOD2, CAT, and GPx4, whereas changes in the level of mRNA of SOD3 in the cerebral cortex of the rat brain were not significant. This was accompanied by activation of antioxidant enzymes (SOD, CAT, GPx, and GST) and increase in reduced glutathione concentration. Under oxidative stress induced by hyperoxia (0.5 MPa for 90 min), the mRNA level of transcription factor Nrf2 decreased, whereas changes in the transcriptional activity of Nrf2-induced genes (SOD1-3, CAT, GPx4) encoding antioxidant enzymes in the cortex of the rat brain hemispheres were insignificant. Under conditions of hyperoxia, lipid peroxidation intensity was increased, CAT was inhibited, and GST activity was moderately increased, whereas SOD and GPx activities in the rat brain cerebral cortex remained at the stationary level. Pretreatment with SkQ1 before the exposure to hyperbaric oxygenation led to an increase in mRNA level of transcription factor Nrf2 and of Nrf2-induced genes (SOD1-2, CAT, and GPx4) encoding antioxidant enzymes, whereas SOD3 expression in the cerebral cortex of the rat brain under oxidative stress was not changed. Concurrently, we observed an increase in activities of these antioxidant enzymes (SOD, CAT, GPx, and GST) and in level of reduced glutathione. We hypothesize that the protective effect of SkQ1 under hyperoxia-induced oxidative stress could be realized via direct antioxidant activity and through stimulation of the signaling defense system Keap1/Nrf2/ARE.

Gypenosides Inhibits Xanthine Oxidoreductase and Ameliorates Urate Excretion in Hyperuricemic Rats Induced by High Cholesterol and High Fat Food (Lipid Emulsion).

BACKGROUND The aim of this study was to study the effects of gypenosides (GPS) on lowering uric acid (UA) levels in hyperuricemic rats induced by lipid emulsion (LE) and the related mechanisms. GPS are natural saponins extracted from Gynostemma pentaphyllum. MATERIAL AND METHODS Forty-eight male SD rats were randomly divided into six groups: normal, model, two positive controls, and two GPS treated groups (two different doses of GPS). The normal group rats were fed a basic diet, and the other rats were orally pretreated with LE. Urine and blood were collected at regular intervals. Full automatic biochemical analyzer was used to detect the concentration levels of serum UA (SUA), serum creatinine (SCr), BUN, and urine UA (UUA), and urine creatinine (UCr) and fractional excretion of UA (FEUA). ELISA kits were used to detect enzymes activities: xanthine oxidase (XOD), adenosime deaminase (ADA), guanine deaminase (GDA), and xanthine dehydrogenase (XDH). Immunohistochemistry was used to observe kidney changes and protein (URAT1, GLUT9, and OAT1) expression levels. RT-PCR was used to detect the relevant mRNA expression levels. RESULTS Treatment with GPS significantly reduced the SUA, prevented abnormal weight loss caused by LE, and improved kidney pathomorphology. Treatment with GPS also decreased the levels of XOD, ADA, and XDH expression, increased the kidney index and FEUA, downregulated URAT1 and GLUT9 expression and upregulated OAT1 expression in the kidney. CONCLUSIONS GPS may be an effective treatment for hyperuricemia via a decrease in xanthine oxidoreductase through the XOD/XDH system; and via an increase in urate excretion through regulating URAT1, GLUT9, and OAT1 transporters.

Is Chronic Curcumin Supplementation Neuroprotective Against Ischemia for Antioxidant Activity, Neurological Deficit, or Neuronal Apoptosis in an Experimental Stroke Model?

AIM: To investigate the neuroprotective effect of chronic curcumin supplementation on the rat forebrain prior to ischemia and reperfusion. MATERIAL AND METHODS: Forebrain ischemia was induced by bilateral common carotid artery occlusion for 1/2 hour, followed by reperfusion for 72 hours. Older rats were divided into five groups: Group I received 300 mg/kg oral curcumin for 21 days before ischemia and 300 mg/kg intraperitoneal curcumin after ischemia; Group II received 300 mg/kg intraperitoneal curcumin after ischemia; Group III received 300 mg/kg oral curcumin for 21 days before ischemia; Group IV had only ischemia; Group V was the sham-operated group. The forebrain was rapidly dissected for biochemical parameter assessment and histopathological examination. RESULTS: In forebrain tissue, enzyme activities of superoxide dismutase, glutathione peroxidase, and catalase were significantly higher in Group I than Groups II or III (p < 0.05) while xanthine dehydrogenase and malondialdehyde enzyme activities and concentrations of interleukin-6 and TNF-alpha were significantly lower in Group I when compared to Groups II and III (p < 0.05). A significant reduction in neurological score was observed after 24 and 72 hours in the curcumin-treated groups compared with the ischemic group. We also found a marked reduction in apoptotic index after 72 hours in the groups receiving curcumin. Significantly more TUNEL-positive cells were observed in the ischemic group compared to those treated with curcumin. CONCLUSION: We demonstrated the neuroprotective effect of chronic curcumin supplement on biochemical parameters, neurological scores and apoptosis following ischemia and reperfusion injury in rats.

Nitrite-mediated reduction of macrophage NADPH oxidase activity is dependent on xanthine oxidoreductase-derived nitric oxide but independent of S-nitrosation.

BACKGROUND: Inorganic nitrite has shown beneficial effects in cardiovascular and metabolic diseases partly via attenuation of NADPH-oxidase (NOX)-mediated oxidative stress. However, the exact mechanisms are still unclear. Here we investigated the role of S-nitrosation or altered expression of NOX subunits, and the role of xanthine oxidoreductase (XOR) in nitrite-derived nitric oxide (NO) production. METHODS: Mouse macrophages were activated with LPS in the presence or absence of nitrite. NOX activity was measured by lucigenin-dependent chemiluminescence. Gene and protein expression of NOX2 subunits and XOR were investigated using qPCR and Western Blot. S-nitrosation of Nox2 and p22phox was studied with a Biotin Switch assay. Uric acid levels in cell culture medium were analyzed as a measure of XOR activity, and NO production was assessed by DAF-FM fluorescence. RESULTS: NOX activity in activated macrophages was significantly reduced by nitrite. Reduced NOX activity was not attributed to decreased NOX gene expression. However, protein levels of p47phox and p67phox subunits were reduced by nitrite in activated macrophages. Protein expression of Nox2 and p22phox was not influenced by this treatment and neither was their S-nitrosation status. Increased uric acid levels after nitrite and diminished NO production during XOR-inhibition with febuxostat suggest that XOR is more active during nitrite-treatment of activated macrophages and plays an important role in the bioactivation of nitrite. CONCLUSIONS: Our findings contribute to the mechanistic understanding about the therapeutic effects associated with nitrite supplementation in many diseases. We show that nitrite-mediated inhibition of NOX activity cannot be explained by S-nitrosation of the NOX enzyme, but that changes in NOX2 expression and XOR function may contribute.

Enhanced XOR activity in eNOS-deficient mice: Effects on the nitrate-nitrite-NO pathway and ROS homeostasis.

Xanthine oxidoreductase (XOR) is generally known as the final enzyme in purine metabolism and as a source of reactive oxygen species (ROS). In addition, this enzyme has been suggested to mediate nitric oxide (NO) formation via reduction of inorganic nitrate and nitrite. This NO synthase (NOS)-independent pathway for NO generation is of particular importance during certain conditions when NO bioavailability is diminished due to reduced activity of endothelial NOS (eNOS) or increased oxidative stress, including aging and cardiovascular disease. The exact interplay between NOS- and XOR-derived NO generation is not fully elucidated yet. The aim of the present study was to investigate if eNOS deficiency is associated with changes in XOR expression and activity and the possible impact on nitrite, NO and ROS homeostasis. Plasma levels of nitrate and nitrite were similar between eNOS deficient (eNOS-/-) and wildtype (wt) mice. XOR activity was upregulated in eNOS-/- compared with wt, but not in nNOS-/-, iNOS-/- or wt mice treated with the non-selective NOS inhibitor L-NAME. Following an acute dose of nitrate, plasma nitrite increased more in eNOS-/- compared with wt, and this augmented response was abolished by the selective XOR inhibitor febuxostat. Livers from eNOS-/- displayed higher nitrite reducing capacity compared with wt, and this effect was attenuated by febuxostat. Dietary supplementation with nitrate increased XOR expression and activity, but concomitantly reduced superoxide generation. The latter effect was also seen in vitro after nitrite administration. Treatment with febuxostat elevated blood pressure in eNOS-/-, but not in wt mice. A high dose of dietary nitrate reduced blood pressure in naïve eNOS-/- mice, and again this effect was abolished by febuxostat. In conclusion, eNOS deficiency is associated with an upregulation of XOR facilitating the nitrate-nitrite-NO pathway and decreasing the generation of ROS. This interplay between XOR and eNOS is proposed to play a significant role in NO homeostasis and blood pressure regulation.

Xanthine dehydrogenase: An old enzyme with new knowledge and prospects.

Xanthine dehydrogenase (EC 1.17.1.4, XDH) is a typical and complex molybdenum-containing flavoprotein which has been extensively studied for over 110 years. This enzyme catalyzes the oxidation of purines, pterin and aldehydes with NAD+ or NADP+ as electron acceptor, and sometimes can be transformed to xanthine oxidase (EC 1.17.3.2, XOD) capable of utilizing oxygen as the electron acceptor. XDHs are widely distributed in all eukarya, bacteria and archaea domains, and are proposed to play significant roles in various cellular processes, including purine catabolism and production of reactive oxygen species (ROS) and nitric oxide (NO) in both physiological and pathological contexts. The recent applications of XDHs include clinical detections of xanthine and hypoxanthine content in body fluidics, and other diagnostic biomarkers like inorganic phosphorus, 5'-nucleotidase and adenosine deaminase. XDHs can also find applications in environmental degradation of pollutants like aldehydes and industrial application in nucleoside drugs like ribavirin. In this commentary, we would outline the latest knowledge on occurrence, structure, biosynthesis, and recent advances of production and applications of XDH, and highlighted the need to develop XDHs with improved performances by gene prospecting and protein engineering, and protocols for efficient production of active XDHs in response to the increasing demands.

Set-up and application of an analytical approach for the quality control of purified colostrum as food supplement.

A validated analytical procedure is here described for the quality control of the protein fraction of purified bovine colostrum used in food supplements. The proposed procedure starts with 1D and 2D-gel electrophoresis. The sample is then separated into two fractions by protein G affinity chromatography: the IgG enriched and the IgG depleted fraction (IgG-d). A size exclusion chromatography coupled to UV is then applied to the IgG and IgG-d fractions for the quantitative analysis of IgG and IgM, respectively. The IgG-d fraction is then analysed by HPLC-MS analysis for the quantitative analysis of ß-lactoglobulins and α-lactoalbumin. The next step is to quantitatively measure a set of bioactive proteins selected from the bovine colostrum data bank on the basis of their claimed health benefits. The enzymatic activities of lactoperoxidase and xanthine dehydrogenase/oxidase are then tested as an index of protein functionality.

Xanthine Oxidoreductase Function Contributes to Normal Wound Healing.

Chronic, nonhealing wounds result in patient morbidity and disability. Reactive oxygen species (ROS) and nitric oxide (NO) are both required for normal wound repair, and derangements of these result in impaired healing. Xanthine oxidoreductase (XOR) has the unique capacity to produce both ROS and NO. We hypothesize that XOR contributes to normal wound healing. Cutaneous wounds were created in C57Bl6 mice. XOR was inhibited with dietary tungsten or allopurinol. Topical hydrogen peroxide (H2O2, 0.15%) or allopurinol (30 µg) was applied to wounds every other day. Wounds were monitored until closure or collected at d 5 to assess XOR expression and activity, cell proliferation and histology. The effects of XOR, nitrite, H2O2 and allopurinol on keratinocyte cell (KC) and endothelial cell (EC) behavior were assessed. We identified XOR expression and activity in the skin and wound edges as well as granulation tissue. Cultured human KCs also expressed XOR. Tungsten significantly inhibited XOR activity and impaired healing with reduced ROS production with reduced angiogenesis and KC proliferation. The expression and activity of other tungsten-sensitive enzymes were minimal in the wound tissues. Oral allopurinol did not reduce XOR activity or alter wound healing but topical allopurinol significantly reduced XOR activity and delayed healing. Topical H2O2 restored wound healing in tungsten-fed mice. In vitro, nitrite and H2O2 both stimulated KC and EC proliferation and EC migration. These studies demonstrate for the first time that XOR is abundant in wounds and participates in normal wound healing through effects on ROS production.

Mammary inflammation around parturition appeared to be attenuated by consumption of fish oil rich in n-3 polyunsaturated fatty acids.

BACKGROUND: Mastitis endangers the health of domestic animals and humans, and may cause problems concerning food safety. It is documented that n-3 polyunsaturated fatty acids (PUFA) play significant roles in attenuating saturated fatty acids (SFA)-induced inflammation. This study was therefore conducted to determine whether mammary inflammation could be affected by consumption of diets rich in n-3 PUFA. METHODS: Forty-eight rats after mating began to receive diets supplemented with 5% fish oil (FO) or 7% soybean oil (SO). Blood and mammary tissue samples (n = 6) at day 0 and 14 of gestation and day 3 postpartum were collected 9 hours after intramammary infusion of saline or lipopolysaccharide (LPS) to determine free fatty acids (FFA) concentration and FA composition in plasma and inflammation mediators in mammary tissues. RESULTS: At day 14 of gestation and day 3 postpartum, the FO-fed rats had lower plasma concentrations of C18:2n6, C20:4n6, total n-6 PUFA and SFA, and higher plasma concentrations of C20:5n3 and total n-3 PUFA than the SO-fed rats. Plasma C22:6n3 concentration was also higher in the FO-fed than in the SO-fed rats at day 3 postpartum. Compared with the SO-fed rats, the FO-fed rats had lower mammary mRNA abundance of xanthine oxidoreductase (XOR) and protein level of tumor necrosis factor (TNF)-α, but had higher mammary mRNA abundances of interleukin (IL)-10 and peroxisome proliferator-activated receptor (PPAR)-γ at day 14 of gestation. Following LPS infusion at day 3 postpartum, the SO-fed rats had increased plasma concentrations of FFA, C18:1n9, C18:3n3, C18:2n6 and total n-6 PUFA, higher mammary mRNA abundances of IL-1ß, TNF-α and XOR but lower mammary mRNA abundance of IL-10 than the FO-fed rats. CONCLUSIONS: Mammary inflammation around parturition appeared to be attenuated by consumption of a diet rich in n-3 PUFA, which was associated with up-regulated expression of IL-10 and PPAR-γ.

Reducing effect of mangiferin on serum uric acid levels in mice.

CONTEXT: Mangiferin, a natural bioactive xanthone C-glycoside, is widely present in medicinal plants like the leaf of Mangifera indica L. (Anacardiaceae). It has been reported that mangiferin possesses a variety of biological activities, including antidiabetic, hepatoprotective, anti-inflammatory, antioxidant, and anticarcinogenic. OBJECTIVE: The hypouricemic effect and xanthine oxidoreductase (XOR) inhibitory activity of mangiferin were investigated here for the first time. MATERIALS AND METHODS: The hypouricemic effect of mangiferin was investigated in normal and hyperuricemic mice induced by potassium oxonate. Mangiferin at a dose of 0.75-100.0 mg/kg was given intragastrically to mice. The serum urate levels were determined using the phosphotungstic acid method. The hepatic activities of xanthine dehydrogenase (XDH) and xanthine oxidase (XOD) in hyperuricemic mice were assayed using commercially available kits. RESULTS: The results showed that mangiferin at a dose of 1.5, 3.0, and 6.0 mg/kg significantly reduced the serum urate levels (148.7 ± 37.8, 142.2 ± 44.5, 121.7 ± 21.7 µmmol/L) in hyperuricemic mice, compared with untreated hyperuricemic mice (201.8 ± 71.2 µmmol/L). However, mangiferin did not decrease the serum urate levels in normal mice until mangiferin was up to 100 mg/kg. In addition, the hepatic activities of XDH in hyperuricemic mice were significantly decreased by mangiferin, while no changes of XOD were observed. Acute toxicity study in mice showed that mangiferin was very safe at a dose of up to 25 g/kg. DISCUSSION AND CONCLUSION: These findings demonstrate that mangiferin has the potential to be developed as a new therapeutic agent for the treatment of hyperuricemia and gout.

Dietary phosphatidylcholine supplementation attenuates inflammatory mucosal damage in a rat model of experimental colitis.

This study was designed to follow the time course of inflammatory activation in a rodent model of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis. We hypothesized that oral phosphatidylcholine (PC) pretreatment regimens may influence leukocyte-mediated microcirculatory reactions in this condition. In series I, Wistar rats were monitored 1 day after colitis induction (n = 24), and in series II (n = 24) on day 6 following a TNBS enema. The PC-pretreated animals received a 2% PC-enriched diet for 6 days before the TNBS enema (series I), or for 3 days before and 3 days after TNBS treatment (series II). The macrohemodynamics, serosal microcirculation (visualized by intravital videomicroscopy), colonic xanthine oxidoreductase, myeloperoxidase and nitric oxide end products, and changes in proinflammatory cytokine levels in plasma were measured. The mucosal structural injury was monitored in vivo by means of confocal laser scanning endomicroscopy. The TNBS enema induced a systemic hyperdynamic circulatory reaction with increased serosal capillary blood flow and significantly elevated colonic inflammatory enzyme activities, levels of nitric oxide production, and cytokine concentrations. Acute colitis caused disruption of the capillary network, whereas the morphologic damage was less severe in series II. The PC pretreatment protocols led to significant decreases in the serosal hyperemic reaction, the cytokine levels, and the inflammatory enzyme activities. The objective signs of tissue damage were reduced in both series, and the number of mucus-producing goblet cells in the resolving phase of colitis was increased. Dietary PC efficiently decreases the cytokine-mediated progression of inflammatory events and preserves the microvascular structure in the large intestine.

Nitric oxide and nitrite-based therapeutic opportunities in intimal hyperplasia.

Vascular intimal hyperplasia (IH) limits the long term efficacy of current surgical and percutaneous therapies for atherosclerotic disease. There are extensive changes in gene expression and cell signaling in response to vascular therapies, including changes in nitric oxide (NO) signaling. NO is well recognized for its vasoregulatory properties and has been investigated as a therapeutic treatment for its vasoprotective abilities. The circulating molecules nitrite (NO(2)(-)) and nitrate (NO(3)(-)), once thought to be stable products of NO metabolism, are now recognized as important circulating reservoirs of NO and represent a complementary source of NO in contrast to the classic L-arginine-NO-synthase pathway. Here we review the background of IH, its relationship with the NO and nitrite/nitrate pathways, and current and future therapeutic opportunities for these molecules.

Protective effects of a phosphatidylcholine-enriched diet in lipopolysaccharide-induced experimental neuroinflammation in the rat.

Our goal was to characterize the neuroprotective properties of orally administered phosphatidylcholine (PC) in a rodent model of systemic inflammation. Sprague-Dawley rats were killed at 3 h, 1 day, 3 days, or 7 days after i.p. administration of lipopolysaccharide (LPS) to determine the plasma levels of tumor necrosis factor α (TNF-α) and interleukin 6 cytokines. The control group and one group of LPS-treated animals were nourished with standard laboratory chow, whereas another LPS-treated group received a special diet enriched with 1% PC for 5 days before the administration of LPS and thereafter during the 7-day observation period. Immunohistochemistry was performed to visualize the bromodeoxyuridine and doublecortin-positive neuroprogenitor cells and Iba1-positive microglia in the hippocampus, whereas the degree of mucosal damage was evaluated on ileal and colon biopsy samples after hematoxylin-eosin staining. The activities of proinflammatory myeloperoxidase and xanthine-oxidoreductase and the tissue nitrite/nitrate (NOx) level were additionally determined, and the cognitive functions were monitored via Morris water maze testing. The inflammatory challenge transiently increased the hippocampal NOx level and led to microglia accumulation and decreased neurogenesis. The intestinal damage, mucosal myeloperoxidase, xanthine-oxidoreductase, and NOx changes were less pronounced, and long-lasting behavioral alterations were not observed. Phosphatidylcholine pretreatment reduced the plasma TNF-α and hippocampal NOx changes and prevented the decreased neurogenesis. These data demonstrated the relative susceptibility of the brain to the consequences of transient peripheral inflammatory stimuli. Phosphatidylcholine supplementation did not reduce the overall extent of peripheral inflammatory activation, but efficiently counteracted the disturbed hippocampal neurogenesis by lowering circulating TNF-α concentrations.