Xanthine oxidoreductase is central to the evolution and function of the innate immune system

Invited review: Mastitis Escherichia coli strains-Mastitis-associated or mammo-pathogenic?

Bovine mastitis remains a major concern for dairy farmers, mainly because of its effect on the economy of their activity and on animal welfare. Because Escherichia coli is considered a major mastitis pathogen, the diversity of E. coli strains isolated from mastitis cases has been studied for decades, with the aim to discover new ways to fight this infection. With the recent advances in whole-genome sequencing, a detailed view of the peculiarities of mastitis E. coli strains has emerged. This review aims to bring together the knowledge garnered over the years with the more recent results of whole-genome analyses. Whereas the concept of a mammary pathogenic E. coli has been proposed, because a common set of virulence genes cannot be identified among mastitis E. coli strains, we prefer the use of mastitis-associated E. coli (MAEC), with MAEC being more an "ecotype" rather than a "pathotype." Indeed, data available so far suggest that a common feature of MAEC would rather be an enrichment in fitness capabilities that makes them well-suited for survival and rapid adaptation to changing biotopes in the mammary gland, which we qualify as intramammary ecotopes.

Quantitative Proteomics Analysis Reveals XDH Related with Ovarian Oxidative Stress Involved in Broodiness of Geese

Studies have demonstrated significant alterations in ovarian oxidative stress levels, ovarian degeneration, and follicular atresia during the broody period in geese. The results of this study showed that during the broody period, geese exhibited degraded ovarian tissues, disrupted follicular development, a thinner granulosa cell layer, and lower levels of ovarian hormones E2, P4, and AMH. Antioxidant activity (GSH, CAT, SOD, T-AOC, and the content of H2O2) and the mRNA expression levels of antioxidant genes (GPX, SOD-1, SOD-2, CAT, COX-2, and Hsp70) were significantly higher in pre-broody geese compared to laying geese, while the expression of apoptosis-related genes (p53, Caspase-3, and Caspase-9) increased and the anti-apoptotic gene Bcl-2 decreased. Additionally, proteomic analysis identified 703 differentially expressed proteins (DEPs), primarily concentrated in the GO categories of the biological process (biological regulation, response to stimulus, etc.) and enriched in the KEGG pathways (PI3K-Akt signaling pathway, etc.). Among them, XDH was central to the regulatory network. Furthermore, Western blotting revealed higher expression of XDH in the ovaries of pre-broody geese than those of laying geese. Pearson correlation analysis indicated a significant correlation between XDH expression and oxidative stress markers in the ovaries of geese (r > 0.75). Overall, these results demonstrated that geese experience ovarian atrophy and remarkably increased oxidative stress during the broody period, suggesting that XDH may be a key driver of broodiness in geese.

Heterocyclic compounds as xanthine oxidase inhibitors for the management of hyperuricemia: synthetic strategies, structure-activity relationship and molecular docking studies (2018-2024)

Hyperuricemia is characterized by higher-than-normal levels of uric acid in the bloodstream. This condition can increase the likelihood of developing gout, a form of arthritis triggered by the deposition of urate crystals in the joints, leading to inflammation and pain. An essential part of purine metabolism is played by the enzyme xanthine oxidase (XO), which transforms xanthine and hypoxanthine into uric acid. Despite its vital role, diseases such as gout have been associated with elevated uric acid levels, which are linked to increased XO activity. To manage hyperuricemia, this study focuses on potential nitrogen based heterocyclic compounds that may serve as XO inhibitors which may lower uric acid levels and prevent hyperuricemia. Xanthine oxidase inhibitors are a class of medications used to treat conditions like gout by reducing the production of uric acid. The present study demonstrates numerous compounds, particularly nitrogen containing heterocyclic compounds including their synthesis, structure-activity relationship, and molecular docking studies. This paper also contains drugs undergoing clinical studies and the xanthine oxidase inhibitors that have been approved by the FDA.

Eupatilin inhibits xanthine oxidase in vitro and attenuates hyperuricemia and renal injury in vivo

Uric acid (UA) is the final metabolite of purines in the liver that can cause hyperuricemia at high levels. The kidneys are the main excretory organs for UA. The excessive accumulation of UA in the kidneys causes the development of hyperuricemia that often leads to renal injury. Eupatilin (Eup) is a flavonoid natural product that possesses various pharmacological properties such as antioxidant, anti-cancer, and anti-inflammatory. We were interested in exploring the potential role of Eup in lowering UA and nephroprotective. We initially investigated the effects of Eup on xanthin oxidase (XOD) activity in vitro, followed by investigating its ability to lower UA levels, anti-inflammatory effects, nephroprotective effects, and the underlying mechanisms using hyperuricemia rats sustained at high UA level. The results showed that Eup had an inhibitory effect on XOD activity in vitro and significantly reduced serum UA, creatinine, BUN, IL-1β and IL-6 levels in hyperuricemic rats, ameliorating inflammation, renal oxidative stress and pathological injury. Furthermore, Eup inhibited ADA and XOD enzyme activities in the liver and serum and modulated GLUT9, URAT1 and ABCG2 protein expression in the kidneys and ileum. Our findings provide a scientific basis for suggesting Eup as an option for a potential treatment for hyperuricemia.

Bovine colostrum and its potential contributions for treatment and prevention of COVID-19

Bovine colostrum (BC) is the initial milk an animal produces after giving birth, particularly in the first few days. Numerous bioactive substances found in BC, including proteins, enzymes, growth factors, immunoglobulins, etc., are beneficial to human health. BC has a significant role to play as part of a healthy diet, with well-documented health and nutritional advantages for people. Therefore, the use of BC and its crucial derivatives in the development of functional food and pharmaceuticals for the prevention of several diseases such as gastrointestinal and respiratory system disorders is becoming increasingly popular around the world. A novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified as the cause of a cluster of pneumonia cases that is called Coronavirus Disease 2019 (COVID-19) in China. After the first SARS-CoV-2 virus-related fatality was announced, the illness quickly spread throughout China and to other continents, causing a pandemic. Since then, numerous studies have been initiated to develop safe and efficient treatments. To prevent viral infection and potential lingering effects, it is important to investigate alternative treatments for COVID-19. Due to its effective bioactive profile and its immunomodulatory roles in biological processes, BC might be considered a promising approach to assist in combating people affected by the SARS-CoV-2 or prevention from the virus. BC has immunomodulatory effects because to its high concentration of bioactive components such as immunoglobulins, lactoferrin, cytokines, and growth factors, etc., which might help control immunological responses, potentially fostering a balanced immune response. Furthermore, its bioactive components have a potential cross-reactivity against SARS-CoV-2, aiding in virus neutralization and its comprehensive food profile also supplies important vitamins, minerals, and amino acids, fostering a healthy immune system. Hence, the possible contributions of BC to the management of COVID-19 were reviewed in this article based on the most recent research on the subject. Additionally, the key BC components that influence immune system modulation were evaluated. These components may serve as potential mediators or therapeutic advantages in COVID-19.

Effects of 2-Year Nutritional and Lifestyle Intervention on Oxidative and Inflammatory Statuses in Individuals of 55 Years of Age and over at High Cardiovascular Risk

Obesity and overweight are disorders with high impact on the morbidity and mortality of chronic diseases, such as type 2 diabetes mellitus (T2DM) and cardiovascular diseases (CVD). We aim to assess the effects of 2-year nutritional and lifestyle intervention on oxidative and inflammatory status in individuals of 55 years of age and over at high CVD risk. Participants (n = 100 individuals of 55 years of age and over living in the Balearic Islands, Spain) were randomized into control and intervention group. Anthropometric and haematological parameters, blood pressure and physical activity were measured before and after the intervention. Oxidative and inflammatory biomarkers in plasma, urine, peripheral blood mononuclear cells (PBMCs) and neutrophils were determined. A higher reduction in abdominal obesity, blood pressure and triglycerides levels was observed after a 2-year intervention. An improvement of oxidative stress and proinflammatory status was demonstrated with a significant reduction in myeloperoxidase, xanthine oxidase, malondialdehyde and monocyte chemoattractant protein-1 (MCP1) levels, and an increase in polyphenols in plasma was observed. A decrease in reactive oxygen species production in PBMCs and neutrophils levels after zymosan and lipopolysaccharide activation was found in the intervention group with respect to the control group. The intervention with hypocaloric Mediterranean Diet and customized physical activity improves oxidative stress and proinflammatory status and could contribute to decreasing the CVD risk.

Xanthine oxidoreductase activity in platelet-poor and rich plasma as a oxidative stress indicator in patients required renal replacement therapy

Background

Xanthine oxidoreductase (XOR) is a hydroxylase enzyme involved in the metabolism of purines. XOR activity can vary: the homodimer protein can be converted into two different isoforms XD (antioxidant) and XO (prooxidant). Oxidative stress and inflammation that accompanying chronic kidney disease (CKD), dialysis, and kidney transplantation, resulted in platelet activation. Present study aimed to determine the influence of applied renal replacement therapy on xanthine oxidoreductase and its isoforms activity.

Materials and Methods

The study group consisted of 117 patients, divided into 4 groups: hemodialysis - 30 patients, peritoneal dialysis - 30 patients, kidney transplant patients - 27 and conservative treatment - 30 patients. The control group consisted of 30 healthy volunteers.

Results

Significant differences were found in XOR activity in platelet-poor plasma (PPP) within the groups studied (p = 0.001). There was a relationship between the type of renal replacement therapy of all oxidoreductase isoforms in PPP (p < 0.001 all isoforms) and XD (p = 0.008), XO (p < 0.001) in platelet rich-plasma (PRP). A relationship was observed between the activity of all oxidoreductase isoforms in PPP and PRP, and the type of renal replacement therapy and the duration of dialysis and the age of patients. The cause of chronic kidney disease was also reflected differences in XD and XO activity in PPP.

Conclusions

The type of renal replacement therapy used in CKD patients, age of patients, duration of dialysis, CKD causes, and stage of progression significantly affect the activity of XOR and its isoforms.

Oxidative Stress in Autism Spectrum Disorder-Current Progress of Mechanisms and Biomarkers

Autism spectrum disorder (ASD) is a type of neurodevelopmental disorder that has been diagnosed in an increasing number of children around the world. Existing data suggest that early diagnosis and intervention can improve ASD outcomes. However, the causes of ASD remain complex and unclear, and there are currently no clinical biomarkers for autism spectrum disorder. More mechanisms and biomarkers of autism have been found with the development of advanced technology such as mass spectrometry. Many recent studies have found a link between ASD and elevated oxidative stress, which may play a role in its development. ASD is caused by oxidative stress in several ways, including protein post-translational changes (e.g., carbonylation), abnormal metabolism (e.g., lipid peroxidation), and toxic buildup [e.g., reactive oxygen species (ROS)]. To detect elevated oxidative stress in ASD, various biomarkers have been developed and employed. This article summarizes recent studies about the mechanisms and biomarkers of oxidative stress. Potential biomarkers identified in this study could be used for early diagnosis and evaluation of ASD intervention, as well as to inform and target ASD pharmacological or nutritional treatment interventions.

The butyrophilin 1a1 knockout mouse revisited: Ablation of Btn1a1 leads to concurrent cell death and renewal in the mammary epithelium during lactation

Butyrophilin 1A1 (BTN1A1) is implicated in the secretion of lipid droplets from mammary epithelial cells as a membrane receptor, which forms a secretion complex with the redox enzyme, xanthine oxidoreductase (XDH). The first evidence that BTN1A1 functions in this process was the generation of Btn1a1 -/- mouse lines, in which lipid secretion was disrupted and large unstable droplets were released into alveolar spaces with fragmented surface membranes. We have revisited one of these mutant mouse lines using RNAseq and proteomic analysis to assess the consequences of ablating the Btn1a1 gene on the expression of other genes and proteins. Disruption of intact Btn1a1 protein expression led to a large build-up of Xdh in the cytoplasm, induction of acute phase response genes and Lif-activation of Stat3 phosphorylation. At peak lactation, approx. 10% of the cells were dying, as assessed by TUNEL-analysis of nuclear DNA. Possible cell death pathways included expression of caspase 8 and activated caspase 3, autophagy, Slc5a8-mediated inactivation of survivin (Birc5), and pStat3-mediated lysosomal lysis, the latter of which is the principal death route in involuting wild type cells. Milk secretion was prolonged by renewal of the secretory epithelium, as evidenced by the upregulation of Ki67 in approx. 10% of cell nuclei and expression of cyclins and Fos/Jun. These data highlight the plasticity of the mammary epithelium and the importance of functional BTN1A1 expression for maintenance of terminally differentiated secretory cells and optimal milk production throughout lactation.

Hyperuricemia Among Egyptian Rheumatoid Arthritis Patients. Is It an Association or an Inflammatory Marker? A Cross-Sectional Observational Study

OBJECTIVE

To detect the prevalence of hyperuricemia in Egyptian rheumatoid arthritis (RA) patients as well as to assess its association with the severity of joint inflammation and disease-modifying antirheumatic drugs (DMARDs) in those patients.

METHODS

A total of 150 RA patients were recruited; all patients were subjected to (1) clinical and functional assessment by disease activity score in 28 joints (DAS28) and modified health assessment questionnaire (MHAQ). (2) Laboratory investigations: serum uric acid (SUA) level, complete blood count (CBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP), tumor necrosis factor α (TNF-α), interleukin 1 (IL1), and interleukin 6 (IL6) levels. (3) Radiological evaluation: (A) plain X-ray of both hands and feet; (B) musculoskeletal ultrasound (MSUS) of both wrists, hands, shoulder, ankle, and knee joints.

RESULTS

SUA was significantly correlated with disease activity by DAS28. Acute-phase reactants and inflammatory markers (IL1β, IL6, and TNF-α) were also significantly elevated in RA patients with low and high hyperuricemia compared to those with normal SUA. A total of 90% of RA patients with low hyperuricemia had synovial proliferation with power Doppler (1+ and 2+), and 30 patients had mild effusion (1+), while nearly all patients with high hyperuricemia had hypoechoic synovial proliferation (2+ and 3+), and 20 patients had moderate effusion. However, 70% RA patients with normal serum uric acid showed mild synovitis and effusion (1+). No significant association was found between the administered DMARDs and levels of SUA as well as inflammatory markers; however, high-dose steroid treatment was associated with high SUA level.

CONCLUSION

Elevation of serum uric acid levels in Egyptian RA patients was prevalent and might be an inflammatory marker for severity of joint inflammation. Moreover, higher doses of steroids could be considered a cause of hyperuricemia.

The Effect of Iron Deficiency Anemia and Different Treatment Methods on DNA Damage: 8-hydroxy-2-deoxyguanosine Level

Ionic iron causes damages at the cellular level by forming free radicals. Reactive oxygen species lead to the formation of oxidative base damages in DNA. Among these forms the most common one and the one which has the best known mutagenity is 8-hydroxy-2′-deoxyguanosine (8-OHdG). We aimed to determine iron deficiency anemia (IDA) and its different forms of treatments; probable oxidative damage on DNA by looking at the level of 8-OHdG. The patients were divided into 4 subgroups: Oral treatment (p.o.) group; Intramuscular treatment (i.m.) group; Intravenous treatment (i.v.) group; Healthy control group. Blood and urine samples were taken from all patients totally 4 times. 8-OHdG levels detected in blood and urine samples were compared with the control group. IDA and the treatment of it affect the level of 8-OHdG. p.o. therapy should be the top priority on children.

The Effect of Chalcones on the Main Sources of Reactive Species Production: Possible Therapeutic Implications in Diabetes Mellitus

Diabetes mellitus (DM) is characterized by hyperglycaemia, resulting from defects in insulin secretion, insulin action or both. There are several factors such as hyperlipidemia and oxidative stress (OS), namely the production of reactive oxygen/nitrogen species (ROS/RNS), that actively contribute to the development and worsening of DM. Chalcones, also termed as benzalacetophenone or benzylidene acetophenone, present a 1,3-diaryl-2-propen-1-one scaffold that has been shown to be highly promising in the development of new antioxidant compounds. Considering the potential interest of antioxidant therapy, the present review scrutinizes the role of the main sources of ROS/RNS production during DM. The modulatory effect of chalcones against nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, xanthine oxidase, mitochondrial respiratory chain and nitric oxide synthase, is also thoroughly discussed, establishing, whenever possible, a structure-activity relationship (SAR). From the SAR analysis, it can be stated that the presence of catechol groups, hydroxyl and methoxyl substituents in the chalcones scaffold improves their modulatory activity against the main sources of ROS/RNS production in DM.

Anti-Hyperuricemic and Nephroprotective Effects of Dihydroberberine in Potassium Oxonate- and Hypoxanthine-Induced Hyperuricemic Mice

Phellodendri Chinese Cortex has long been used to treat hyperuricemia and gout. Berberine (BBR), its characteristic ingredient, has also been shown to be effective in alleviating monosodium urate crystals-triggered gout inflammation in vitro and in vivo. Dihydroberberine (DHB) is a hydrogenated derivative of BBR that showed improved in vivo efficacy on many metabolic disorders. However, its anti-hyperuricemia effect remains underexplored. In the present work, the hypouricemic and renoprotective effects of DHB on hyperuricemic mice were investigated. The hyperuricemic mice model was induced by intraperitoneal injection of potassium oxonate (PO, 300 mg/kg) combined with intragastric administration of hypoxanthine (HX, 300 mg/kg) for 7 days. Different dosages of DHB (25, 50 mg/kg), BBR (50 mg/kg) or febuxostat (Feb, 5 mg/kg) were orally given to mice 1 h after modeling. The molecular docking results showed that DHB effectively inhibited xanthine oxidase (XOD) by binding with its active site. In vitro, DHB exhibited significant XOD inhibitory activity (IC₅₀ value, 34.37 μM). The in vivo results showed that DHB had obvious hypouricemic and renoprotective effects in hyperuricemic mice. It could not only lower the uric acid and XOD levels in serum, but also suppress the activities of XOD and adenosine deaminase (ADA) in the liver. Furthermore, DHB noticeably down-regulated the renal mRNA and protein expression of XOD. Besides, DHB remarkably and dose-dependently ameliorated renal damage, as evidenced by considerably reducing serum creatinine and blood urea nitrogen (BUN) levels, inflammatory cytokine (TNF-α, IL-1β, IL-6 and IL-18) levels and restoring kidney histological deteriorations. Further mechanistic investigation showed that DHB distinctly down-regulated renal mRNA and protein levels of URAT1, GLUT9, NOD-like receptor 3 (NLRP3), apoptosis-associated speck-like (ASC), caspase-1 and IL-1β. Our study revealed that DHB had outstanding hypouricemic and renoprotective effects via suppressing XOD, URAT1, GLUT9 and NLRP3 inflammasome activation in the kidney.

Purification and characterization of an FeII- and α-ketoglutarate-dependent xanthine hydroxylase from Aspergillus oryzae

XanA is an Fe^II- and α-ketoglutarate-dependent enzyme responsible for the conversion of xanthine to uric acid. It is unique to fungi and it was first described in Aspergillus nidulans. In this work, we present the preliminary characterization of the XanA enzyme from Aspergillus oryzae, a relevant fungus in food production in Japan. The XanA protein (GenBank BAE56701.1) was expressed as a recombinant protein in Escherichia coli BL21 (DE3) Arctic cells. Initial purification assays showed low protein solubility; therefore, the buffer composition was optimized using a fluorescence-based thermal shift assay. The protein was stabilized in solution in the presence of either 600 μM xanthine, 1 M NaCl, 600 μM α-ketoglutarate or 20% glycerol, which increases the melting temperature (T_m) by 2, 4, 5 and 6 °C respectively. The XanA protein was purified by following a three-step purification protocol. The nickel affinity purified protein was subjected to ion-exchange chromatography once the N-terminal 6XHis-tag had been successfully removed, followed by size-exclusion purification. Dynamic light scattering experiments showed that the purified protein was monodisperse and behaved as a monomer in solution. Preliminary activity assays in the presence of xanthine, α-ketoglutarate, and iron suggest that the enzyme is an iron- and α-ketoglutarate-dependent xanthine dioxygenase. Furthermore, the enzyme's optimum activity conditions were determined to be 25 °C, pH of 7.2, HEPES buffer, and 1% of glycerol. In conclusion, we established the conditions to purify the XanA enzyme from A. oryzae in its active form from E. coli bacteria and determined the optimal activity conditions.

A feasibility study of metabolic phenotyping of dried blood spot specimens in rural Chinese women exposed to household air pollution

BACKGROUND

Exposure-response studies and policy evaluations of household air pollution (HAP) are limited by current methods of exposure assessment which are expensive and burdensome to participants.

METHODS

We collected 152 dried blood spot (DBS) specimens during the heating and non-heating seasons from 53 women who regularly used biomass-burning stoves for cooking and heating. Participants were enrolled in a longitudinal study in China. Untargeted metabolic phenotyping of DBS were generated using ultra-high performance liquid chromatography coupled with mass spectrometry to exemplify measurement precision and assessment for feasibility to detect exposure to HAP, evaluated by season (high pollution vs. low pollution) and measured personal exposure to fine particulate matter <2.5 μm diameters (PM2.5) and black carbon (BC) in the 48-h prior to collecting the DBS specimen.

RESULTS

Metabolites e.g., amino acids, acyl-carnitines, lyso-phosphorylcholines, sphinganine, and choline were detected in the DBS specimens. Our approach is capable of detecting the differences in personal exposure to HAP whilst showing high analytical reproducibility, coefficient of variance (CV) <15%, meeting the U.S. Food and Drug Administration criteria.

CONCLUSIONS

Our results provide a proof of principle that high-resolution metabolic phenotypic data can be generated using a simple DBS extraction method thus suitable for exposure studies in remote, low-resource settings where the collection of serum and plasma is logistically challenging or infeasible. The analytical run time (19 min/specimen) is similar to most global phenotyping methods and therefore suitable for large-scale application.

Reactive oxygen and nitrogen species and innate immune response

The innate immune system is the first line of defense against pathogens and is characterized by its fast but nonspecific response. One important mechanism of this system is the production of the biocidal reactive oxygen and nitrogen species, which are widely distributed within biological systems, including phagocytes and secretions. Reactive oxygen and nitrogen species are short-lived intermediates that are biochemically synthesized by various enzymatic reactions in aerobic organisms and are regulated by antioxidants. The physiological levels of reactive species play important roles in cellular signaling and proliferation. However, higher concentrations and prolonged exposure can fight infections by damaging important microbial biomolecules. One feature of the reactive species generation system is the interaction between its components to produce more biocidal agents. For example, the phagocytic NADPH oxidase complex generates superoxide, which functions as a precursor for antimicrobial hydrogen peroxide synthesis. Peroxide is then used by myeloperoxidase in the same cells to generate hypochlorous acid, a highly microbicidal agent. Studies on animal models and microorganisms have shown that deficiency of these antimicrobial agents is associated with severe recurrent infections and immunocompromised diseases, such as chronic granulomatous disease. There is accumulating evidence that reactive species have important positive aspects on human health and immunity; however, some important promising features of this system remain obscure.

Xanthine oxidase-lactoperoxidase system and innate immunity: Biochemical actions and physiological roles

The innate immune system in mammals is the first-line defense that plays an important protective role against a wide spectrum of pathogens, especially during early life before the adaptive immune system develops. The enzymes xanthine oxidase (XO) and lactoperoxidase (LPO) are widely distributed in mammalian tissues and secretions, and have a variety of biological functions including in innate immunity, provoking much interest for both in vitro and in vivo applications. The enzymes are characterized by their generation of reactive oxygen and nitrogen species, including hydrogen peroxide, hypothiocyanite, nitric oxide, and peroxynitrite. XO is a major generator of hydrogen peroxide and superoxide that subsequently trigger a cascade of oxidative radical pathways, including those produced by LPO, which have bactericidal and bacteriostatic effects against pathogens including opportunistic bacteria. In addition to their role in host microbial defense, reactive oxygen and nitrogen species play important physiological roles as second messenger cell signaling molecules, including cellular proliferation, differentiation and gene expression. There are several indications that the reactive species generated by peroxide have positive effects on human health, particularly in neonates; however, some important in vivo aspects of this system remain obscure. The primary dependence of the system on hydrogen peroxide has led us to propose it is particularly relevant to neonate mammals during milk feeding.

A proteomic study of resistance to Brown Ring disease in the Manila clam, Ruditapes philippinarum

Marine mollusk aquaculture has more than doubled over the past twenty years, accounting for over 15% of total aquaculture production in 2016. Infectious disease is one of the main limiting factors to the development of mollusk aquaculture, and the difficulties inherent to combating pathogens through antibiotic therapies or disinfection have led to extensive research on host defense mechanisms and host-pathogen relationships. It has become increasingly clear that characterizing the functional profiles of response to a disease is an essential step in understanding resistance mechanisms and moving towards more effective disease control. The Manila clam, Ruditapes philippinarum, is a main cultured bivalve species of economic importance which is affected by Brown Ring disease (BRD), an infection induced by the bacterium Vibrio tapetis. In this study, juvenile Manila clams were subjected to a 28-day controlled challenge with Vibrio tapetis, and visual and molecular diagnoses were carried out to distinguish two extreme phenotypes within the experimental clams: uninfected ("RES", resistant) and infected ("DIS", diseased) post-challenge. Total protein extractions were carried out for resistant and diseased clams, and proteins were identified using LC-MS/MS. Protein sequences were matched against a reference transcriptome of the Manila clam, and protein intensities based on label-free quantification were compared to reveal 49 significantly accumulated proteins in resistant and diseased clams. Proteins with known roles in pathogen recognition, lysosome trafficking, and various aspects of the energy metabolism were more abundant in diseased clams, whereas those with roles in redox homeostasis and protein recycling were more abundant in resistant clams. Overall, the comparison of the proteomic profiles of resistant and diseased clams after a month-long controlled challenge to induce the onset of Brown Ring disease suggests that redox homeostasis and maintenance of protein structure by chaperone proteins may play important and interrelated roles in resistance to infection by Vibrio tapetis in the Manila clam.

Uric acid increases IL-1β secretion and Caspase-1 activation in PBMCs of Behçet's disease patients: The in vitro immunomodulatory effect of xanthine oxidase inhibitor Allopurinol

Behçet's disease (BD) is a multisystem disease, which shares some features with other diseases belonging to the autoinflammatory disorders panel. Recent studies have postulated that IL-1β/Caspase-1 may play a cardinal role in autoinflammatory diseases. In this study, we aimed to (i) elucidate the mechanism underlying the involvement of xanthine oxidase (XO) and Uric Acid (UA) in BD (ii) study the direct effects of UA and XO inhibitor "Allopurinol" on nitric oxide (NO) and caspase-1-mediated IL-1β release in peripheral blood mononuclear cells (PBMCs) of BD patients. In this context, plasma of BD patients and healthy controls (HC) were used to measure XO activity, UA, advanced oxidized proteins products (AOPP) and NO levels. In Addition, PBMCs of BD patients and HC were treated or not with either UA or Allopurinol. Then we quantified NO and IL-1β levels, and Caspase-1 Activity in the supernatants and lysates of PBMCs, respectively. We showed that plasma levels of XO activity, UA, AOPP and NO are significantly increased in BD patients compared to those of HC. Interestingly, a significant positive correlation between XO and UA was observed in BD patients. Additionally, while UA has markedly increased NO, IL-1β, and Caspase-1 activity levels in PBMCs of BD patients, Allopurinol has exerted an immunomodulatory effect resulting in reduced NO, IL-1β and Caspase-1 levels in PBMCs of BD patients particularly during the active stages. Collectively, our results indicate a potential clinical use of XO as a tool for assessing BD activity, and suggest that the in-vitro immunomodulatory effect of Allopurinol may have a promising therapeutic value in BD management.

Primary Metabolite Responses to Oxidative Stress in Early-Senescing and Paraquat Resistant Arabidopsis thaliana rcd1 (Radical-Induced Cell Death1)

Rcd1 (radical-induced cell death1) is an Arabidopsis thaliana mutant, which exhibits high tolerance to paraquat [methyl viologen (MV)], herbicide that interrupts photosynthetic electron transport chain causing the formation of superoxide and inhibiting NADPH production in the chloroplast. To understand the biochemical mechanisms of MV-resistance and the role of RCD1 in oxidative stress responses, we performed metabolite profiling of wild type (Col-0) and rcd1 plants in light, after MV exposure and after prolonged darkness. The function of RCD1 has been extensively studied at transcriptomic and biochemical level, but comprehensive metabolite profiling of rcd1 mutant has not been conducted until now. The mutant plants exhibited very different metabolic features from the wild type under light conditions implying enhanced glycolytic activity, altered nitrogen and nucleotide metabolism. In light conditions, superoxide production was elevated in rcd1, but no metabolic markers of oxidative stress were detected. Elevated senescence-associated metabolite marker levels in rcd1 at early developmental stage were in line with its early-senescing phenotype and possible mitochondrial dysfunction. After MV exposure, a marked decline in the levels of glycolytic and TCA cycle intermediates in Col-0 suggested severe plastidic oxidative stress and inhibition of photosynthesis and respiration, whereas in rcd1 the results indicated sustained photosynthesis and respiration and induction of energy salvaging pathways. The accumulation of oxidative stress markers in both plant lines indicated that MV-resistance in rcd1 derived from the altered regulation of cellular metabolism and not from the restricted delivery of MV into the cells or chloroplasts. Considering the evidence from metabolomic, transcriptomic and biochemical studies, we propose that RCD1 has a negative effect on reductive metabolism and rerouting of the energy production pathways. Thus, the altered, highly active reductive metabolism, energy salvaging pathways and redox transfer between cellular compartments in rcd1 could be sufficient to avoid the negative effects of MV-induced toxicity.

Formation and degradation of lipid droplets in human adipocytes and the expression of aldehyde oxidase (AOX)

Lipid droplet (LD) binding proteins in mammary glands and in adipocytes were previously compared and striking similar sets of these specific proteins demonstrated. Xanthine oxidoreductase (XOR) together with perilipins and the lactating mammary gland protein butyrophilin play an important role in the secretion process of LDs into milk ducts. In contrast, in adipose tissue and in adipocytes, mainly perilipins have been described. Moreover, XOR was reported in mouse adipose tissue and adipocyte culture cells as “novel regulator of adipogenesis”. This obvious coincidence of protein sets prompted us to revisit the formation of LDs in human-cultured adipocytes in more detail with special emphasis on the possibility of a LD association of XOR. We demonstrate by electron and immunoelectron microscopy new structural details on LD formation in adipocytes. Surprisingly, by immunological and proteomic analysis, we identify in contrast to previous data showing the enzyme XOR, predominantly the expression of aldehyde oxidase (AOX). AOX could be detected tightly linked to LDs when adipocytes were treated with starvation medium. In addition, the majority of cells show an enormous interconnected, tubulated mitochondria network. Here, we discuss that (1) XOR is involved—together with perilipins—in the secretion of LDs in alveolar epithelial cells of the lactating mammary gland and is important in the transcytosis pathway of capillary endothelial cells. (2) In cells, where LDs are not secreted, XOR cannot be detected at the protein level, whereas in contrast in these cases, AOX is often present. We detect AOX in adipocytes together with perilipins and find evidence that these proteins might direct LDs to mitochondria. Finally, we here report for the first time the exclusive and complementary localization of XOR and AOX in diverse cell types.

The antimicrobial activity of bovine milk xanthine oxidase

Mammalian milk is a source of antimicrobial compounds such as xanthine oxidase (XO). The interplay of infant saliva, which contains the substrates for XO activity, and human milk containing XO has been recently shown to inhibit the growth of pathogenic bacteria. Based on the complex and protective mechanism observed in human milk, we hypothesized that bovine milk XO operates similarly, thus representing an opportunity to investigate its functionality in broader health implications. We demonstrated that bovine milk-hypoxanthine mixture (0 to 400 μM) inhibited several Gram-negative and -positive bacterial pathogens in a dose-dependent manner. Kinetic experiments revealed that XO catalyzed hypoxanthine reduction (K_m, 58.0 μM; V_max, 5.1 μmol^-1 min^-1 mg) resulted in the production of antimicrobial hydrogen peroxide. These results demonstrate that the antimicrobial properties of bovine milk XO are similar to those of human milk XO with significant implications for the development of novel products targeting infant health.

Effects of industrial heat treatments on the kinetics of inactivation of antimicrobial bovine milk xanthine oxidase

Milk is a source of antimicrobial systems such as xanthine oxidoreductase, which has been proposed to modulate the oral and gut microbiota of infants. Heat treatments are applied to milk to ensure its microbial safety, however, the effects of heat on this antimicrobial enzyme are not known. The effects of batch pasteurization (BP), high-temperature short time (HTST), and ultra high temperature (UHT) on kinetics of inactivation of xanthine oxidase and its antimicrobial properties were determined. Xanthine oxidase activity was preserved by HTST (100%). Partial (8%) and nearly complete (95%) enzyme inactivation were observed for BP and UHT milks, respectively. K_m values of 100 μM and V_max values of 6.85, 5.12, 6.31, and 0.40 μmol/min/mg were determined for xanthine oxidase in raw, BP, HTST, and UHT milks, respectively. These results demonstrate that xanthine oxidase maintains apparent affinity and activity for its substrate when milk is treated by BP and HTST and yet the enzyme is inactivated with UHT. To investigate heat treatment-induced alterations in the biological activity of xanthine oxidase, heat treated milks were compared to raw milk for their ability to inhibit the growth of S. aureus. Raw, BP, and HTST milk xanthine oxidase efficiently inhibited S. aureus growth. However, these antibacterial properties were lost when milk was subjected to UHT. These results demonstrate that HTST and BP preserves bovine milk xanthine oxidase activity compared with UHT and that, the judicious selection of thermal treatments could be exploited to preserve the antimicrobial properties of bovine milk.

Symposium review: Intravital imaging of the lactating mammary gland in live mice reveals novel aspects of milk-lipid secretion

Milk fat comprises membrane-coated droplets of neutral lipid, which constitute the predominant source of lipids for survival of the suckling neonate. From the perspective of the dairy industry, they are the basis for the manufacture of butter and essential ingredients in the production of cheese, yogurt, and specialty dairy produce. To provide mechanistic insight into the assembly and secretion of lipid droplets during lactation, we developed novel intravital imaging techniques using transgenic mice, which express fluorescently tagged marker proteins. The number 4 mammary glands were surgically prepared under a deep plane of anesthesia and the exposed glands positioned as a skin flap with intact vascular supply on the stage of a laser-scanning confocal microscope. Lipid droplets were stained by prior exposure of the glands to hydrophobic fluorescent BODIPY (boron-dipyrromethene) dyes and their formation and secretion monitored by time-lapse subcellular microscopy over periods of 1 to 2 h. Droplets were transported to the cell apex by directed (superdiffusive) motion at relatively slow and intermittent rates (0-2 µm/min). Regardless of size, droplets grew by numerous fusion events during transport and as they were budding from the cell enveloped by apical membranes. Surprisingly, droplet secretion was not constitutive but required an injection of oxytocin to induce contraction of the myoepithelium with subsequent release of droplets into luminal spaces. These novel results are discussed in the context of the current paradigm for milk fat synthesis and secretion and as a template for future innovations in the dairy industry.

Correlations between related-purine derivatives and renal disorders in patients with psoriasis vulgaris

Recent data suggest that severe psoriasis is an independent risk factor for chronic renal disease. In the present study, we investigated the role of related-purine derivatives as predictors of renal dysfunctions in patients with psoriasis. A prospective study was conducted on a group of 45 patients with psoriasis vulgaris and 45 control cases, monitored over a 5-year period. Alterations of renal function, albumin/creatinine ratio (ACR, mg/g) and UA/creatinine ratio (UACR, mg/mg) were determined in spontaneous urine samples. The status of related-purine derivatives was evaluated by quantification of uric acid (UA, mg/dl), adenosine deaminase (ADA, UI/mg protein), xanthine oxidase (XO, UI/mg protein) and 8-hydroxy-deoxy-guanosine levels (8-OHdG, ng/ml) in serum samples. Compared to the controls, in patients with psoriasis there was an increase in related-purine derivatives levels, which was demonstrated by the elevated serum levels of UA (5.1±0.4 vs. 5.4±1.0, P=0.066), ADA (0.14±0.08 vs. 0.29±0.12, P=0.052), XO (0.22±0.11 vs. 0.42±0.21, P=0.011) and 8-OHdG (3.1±0.05 vs. 8.3±4.7, P=0.002). The serum levels of related-purine derivatives were associated with the severity of psoriasis. In addition, there was a link between the serum levels of related-purine derivatives and markers of renal impairment. There were positive correlations between 8-OHdG and ACR (r=0.452, P=0.028) and between ADA, XO, UA, 8-OHdG and UACR (r=0.297 and P=0.032, r=0.301 and P=0.002, r=0.431 and P=0.027, r=0.508 and P=0.002) and negative correlations between UA, 8-OHdG and the estimated glomerular filtration rate (r=-0.301 and P=0.036, r=-0.384 and P=0.002). Thus, severe psoriasis is a risk factor for the development of renal disease.

Analysis of the Effect of Intestinal Ischemia and Reperfusion on the Rat Neutrophils Proteome

Intestinal ischemia and reperfusion injury is a model system of possible consequences of severe trauma and surgery, which might result into tissue dysfunction and organ failure. Neutrophils contribute to the injuries preceded by ischemia and reperfusion. However, the mechanisms by which intestinal ischemia and reperfusion stimulate and activate circulating neutrophils is still not clear. In this work, we used proteomics approach to explore the underlying regulated mechanisms in Wistar rat neutrophils after ischemia and reperfusion. We isolated neutrophils from three different biological groups; control, sham laparotomy, and intestinal ischemia/reperfusion. In the workflow, we included iTRAQ-labeling quantification and peptide fractionation using HILIC prior to LC-MS/MS analysis. From proteomic analysis, we identified 2,045 proteins in total that were grouped into five different clusters based on their regulation trend between the experimental groups. A total of 417 proteins were found as significantly regulated in at least one of the analyzed conditions. Interestingly, the enzyme prediction analysis revealed that ischemia/reperfusion significantly reduced the relative abundance of most of the antioxidant and pro-survival molecules to cause more tissue damage and ROS production whereas some of the significantly up regulated enzymes were involved in cytoskeletal rearrangement, adhesion and migration. Clusters based KEGG pathways analysis revealed high motility, phagocytosis, directional migration, and activation of the cytoskeletal machinery in neutrophils after ischemia and reperfusion. Increased ROS production and decreased phagocytosis were experimentally validated by microscopy assays. Taken together, our findings provide a characterization of the rat neutrophil response to intestinal ischemia and reperfusion and the possible mechanisms involved in the tissue injury by neutrophils after intestinal ischemia and reperfusion.

An effort toward molecular neuroeconomics of food deprivation induced food hoarding in mice: focus on xanthine oxidoreductase gene expression and xanthine oxidase activity

The crucial role of xanthine oxidoreductase (XOR) gene and its active isoform, xanthine oxidase (XO), in purine metabolism and cellular oxidative status led us to investigative their fluctuations in food deprivation induced food hoarding in mice. After, 10 h food deprivation, mice that hoarded lesser than 5 g were considered as 'low-hoarders' while mice that hoarded higher than 20 g were considered as 'high-hoarders'. Mice who hoarded between 5 to 20 g of food were excluded from study. An increase (1.133-fold) in encephalic XOR expression has been found in high-hoarders compared with low-hoarders without sex consideration. An increase (~ 50-fold) in encephalic XOR in female high-hoarders vs. female low-hoarders while a decrease (0.026-fold) in encephalic XOR in male high-hoarders vs. male low-hoarders demonstrated that food deprivation is associated with sex-dependent alteration in XOR expression. The encephalic and hepatic XO activities were not different in male high-hoarders vs. male low-hoarders while encephalic XO activity has been also increased significantly in female high-hoarders (~ 4 times) compared to female low-hoarders. The plasma and hepatic XO activities tended to be increased in female high-hoarders as compared to female low-hoarders, however the uric acid levels in plasma, liver and brain tissues were not altered in female high-hoarders as compared to female low-hoarders. In sum, this study generally proposed that different gene expression space is behind of hoarding behavior in a food-deprived mouse model. Specifically, this is the first study that examined the levels of encephalic XO activity and XOR expression in hoarding behavior, although additional studies are requested.

Rapid changes in Atlantic grey seal milk from birth to weaning - immune factors and indicators of metabolic strain

True seals have the shortest lactation periods of any group of placental mammal. Most are capital breeders that undergo short, intense lactations, during which they fast while transferring substantial proportions of their body reserves to their pups, which they then abruptly wean. Milk was collected from Atlantic grey seals (Halichoerus grypus) periodically from birth until near weaning. Milk protein profiles matured within 24 hours or less, indicating the most rapid transition from colostrum to mature phase lactation yet observed. There was an unexpected persistence of immunoglobulin G almost until weaning, potentially indicating prolonged trans-intestinal transfer of IgG. Among components of innate immune protection were found fucosyllactose and siallylactose that are thought to impede colonisation by pathogens and encourage an appropriate milk-digestive and protective gut microbiome. These oligosaccharides decreased from early lactation to almost undetectable levels by weaning. Taurine levels were initially high, then fell, possibly indicative of taurine dependency in seals, and progressive depletion of maternal reserves. Metabolites that signal changes in the mother’s metabolism of fats, such as nicotinamide and derivatives, rose from virtual absence, and acetylcarnitines fell. It is therefore possible that indicators of maternal metabolic strain exist that signal the imminence of weaning.

Targeting the NO/superoxide ratio in adipose tissue: relevance to obesity and diabetes management

Insulin sensitivity and metabolic homeostasis depend on the capacity of adipose tissue to take up and utilize excess glucose and fatty acids. The key aspects that determine the fuel-buffering capacity of adipose tissue depend on the physiological levels of the small redox molecule, nitric oxide (NO). In addition to impairment of NO synthesis, excessive formation of the superoxide anion (О2•- ) in adipose tissue may be an important interfering factor diverting the signalling of NO and other reactive oxygen and nitrogen species in obesity, resulting in metabolic dysfunction of adipose tissue over time. Besides its role in relief from superoxide burst, enhanced NO signalling may be responsible for the therapeutic benefits of different superoxide dismutase mimetics, in obesity and experimental diabetes models. This review summarizes the role of NO in adipose tissue and highlights the effects of NO/О2•- ratio 'teetering' as a promising pharmacological target in the metabolic syndrome.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

Fructose Intake, Serum Uric Acid, and Cardiometabolic Disorders: A Critical Review

There is a direct relationship between fructose intake and serum levels of uric acid (UA), which is the final product of purine metabolism. Recent preclinical and clinical evidence suggests that chronic hyperuricemia is an independent risk factor for hypertension, metabolic syndrome, and cardiovascular disease. It is probably also an independent risk factor for chronic kidney disease, Type 2 diabetes, and cognitive decline. These relationships have been observed for high serum UA levels (>5.5 mg/dL in women and >6 mg/dL in men), but also for normal to high serum UA levels (5-6 mg/dL). In this regard, blood UA levels are much higher in industrialized countries than in the rest of the world. Xanthine-oxidase inhibitors can reduce UA and seem to minimize its negative effects on vascular health. Other dietary and pathophysiological factors are also related to UA production. However, the role of fructose-derived UA in the pathogenesis of cardiometabolic disorders has not yet been fully clarified. Here, we critically review recent research on the biochemistry of UA production, the relationship between fructose intake and UA production, and how this relationship is linked to cardiometabolic disorders.

Role of macrophages in age-related oxidative stress and lipofuscin accumulation in mice

The age-related changes in the immune functions (immunosenescence) may be mediated by an increase of oxidative stress and damage affecting leukocytes. Although the “oxidation-inflammation” theory of aging proposes that phagocytes are the main immune cells contributing to “oxi-inflamm-aging”, this idea has not been corroborated. The aim of this work was to characterize the age-related changes in several parameters of oxidative stress and immune function, as well as in lipofuscin accumulation (“a hallmark of aging”), in both total peritoneal leukocyte population and isolated peritoneal macrophages. Adult, mature, old and long-lived mice (7, 13, 18 and 30 months of age, respectively) were used. The xanthine oxidase (XO) activity-expression, basal levels of superoxide anion and ROS, catalase activity, oxidized (GSSG) and reduced (GSH) glutathione content and lipofuscin levels, as well as both phagocytosis and digestion capacity were evaluated. The results showed an age-related increase of oxidative stress and lipofuscin accumulation in murine peritoneal leukocytes, but especially in macrophages. Macrophages from old mice showed lower antioxidant defenses (catalase activity and GSH levels), higher oxidizing compounds (XO activity/expression and superoxide, ROS and GSSG levels) and lipofuscin levels, together with an impaired macrophage functions, in comparison to adults. In contrast, long-lived mice showed in their peritoneal leukocytes, and especially in macrophages, a well-preserved redox state and maintenance of their immune functions, all which could account for their high longevity. Interestingly, macrophages showed higher XO activity and lipofuscin accumulation than lymphocytes in all the ages analyzed. Our results support that macrophages play a central role in the chronic oxidative stress associated with aging, and the fact that phagocytes are key cells contributing to immunosenescence and “oxi-inflamm-aging”. Moreover, the determination of oxidative stress and immune function parameters, together with the lipofuscin quantification, in macrophages, can be used as useful markers of the rate of aging and longevity.

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Peritoneal macrophages from old mice have higher oxidant levels than lymphocytes.

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Long-lived mice have a well-preserved redox state in both macrophages and lymphocytes.

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Peritoneal macrophages have higher lipofuscin levels than lymphocytes along aging.

Role of Uric Acid Metabolism-Related Inflammation in the Pathogenesis of Metabolic Syndrome Components Such as Atherosclerosis and Nonalcoholic Steatohepatitis

Uric acid (UA) is the end product of purine metabolism and can reportedly act as an antioxidant. However, recently, numerous clinical and basic research approaches have revealed close associations of hyperuricemia with several disorders, particularly those comprising the metabolic syndrome. In this review, we first outline the two molecular mechanisms underlying inflammation occurrence in relation to UA metabolism; one is inflammasome activation by UA crystallization and the other involves superoxide free radicals generated by xanthine oxidase (XO). Importantly, recent studies have demonstrated the therapeutic or preventive effects of XO inhibitors against atherosclerosis and nonalcoholic steatohepatitis, which were not previously considered to be related, at least not directly, to hyperuricemia. Such beneficial effects of XO inhibitors have been reported for other organs including the kidneys and the heart. Thus, a major portion of this review focuses on the relationships between UA metabolism and the development of atherosclerosis, nonalcoholic steatohepatitis, and related disorders. Although further studies are necessary, XO inhibitors are a potentially novel strategy for reducing the risk of many forms of organ failure characteristic of the metabolic syndrome.

Similar developmental fluctuations of hepato-renal xanthine oxidoreductase gene expression and xanthine oxidase activity in layer and broiler chicken embryos

1. Xanthine oxidase (XO) has many physiological functions associated with the synthesis of both antioxidant (uric acid: UA) and numerous oxidants (e.g. H₂O₂), which makes it an important regulator of the cellular redox potential involving organogenesis. The ontogenetic study of hepatic and renal XO makes a better understanding of the putative role of this enzyme in the development of these tissues. 2. Developmental changes of gene expression of xanthine oxidoreductase (XOR), XO activity and UA content of liver and kidney tissues in both broiler and layer chicken embryos were examined during incubation d 14-21. 3. In both strains, hepatic XOR gene expression peaked on d 21 while renal XOR gene expression did not change. 4. The XO activity was higher in kidney than liver in both strains. Hepatic XO activity of both strains peaked on d 18 and thereafter was decreased on d 21. Renal XO activity peaked on d 18 and from then on did not show any significant changes until d 21 in both strains. 5. The UA content was higher in kidney vs. liver in both strains. The hepatic and renal UA values of the both strains increased significantly from d 14 to d 21. 6. The present results showed dissimilar behaviour of XOR gene expression, XO activity and UA content of liver and kidney tissues in both broiler and layer chicken embryos.

Weight gain by gut microbiota manipulation in productive animals

Antibiotics, prebiotics and probiotics are widely used as growth promoters in agriculture. In the 1940s, use of Streptomyces aureofaciens probiotics resulted in weight gain in animals, which led to the discovery of chlortetracycline. Tetracyclines, macrolides, avoparcin and penicillins have been commonly used in livestock agriculture to promote growth through increased food intake, weight gain, and improved herd health. Prebiotic supplements including oligosaccharides, fructooligosaccharides, and galactosyl-lactose improve the growth performance of animals. Probiotics used in animal feed are mainly bacterial strains of Gram-positive bacteria and have been effectively used for weight gain in chickens, pigs, ruminants and in aquaculture. Antibiotics, prebiotics and probiotics all modify the gut microbiota and the effect of a probiotic species on the digestive flora is probably determined by bacteriocin production. Regulations governing the introduction of novel probiotics and prebiotics vary by geographical region and bias is very common in industry-funded studies. Probiotic and prebiotic foods have been consumed for centuries, either as natural components of food, or as fermented foods and it is possible to cause the same weight gain effects in humans as in animals. This review presents the use of growth promoters in food-producing animals to influence food intake and weight gain.

Mediterranean diets supplemented with virgin olive oil and nuts enhance plasmatic antioxidant capabilities and decrease xanthine oxidase activity in people with metabolic syndrome: The PREDIMED study

SCOPE

This study assessed plasmatic antioxidant capabilities and xanthine oxidase (XOX) activity in metabolic syndrome patients after 5 years intervention with Mediterranean diet (MeDiet) supplemented with extra-virgin olive oil or with nuts or with low-fat diet (the PREDIMED [PREvención con Dieta MEDiterránea] study).

METHODS AND RESULTS

Seventy-five participants were randomly selected. Daily energy and nutrient intake were assessed with a validated 137-item food frequency questionnaire, and adherence to the MeDiet was assessed using a 14-item questionnaire. Catalase, superoxide dismutase (SOD), myeloperoxidase, XOX activities and protein levels, and protein carbonyl derivatives, nitrotyrosine, nitrite and nitrate levels were determined in overnight fasting venous blood samples. The plasma activity and protein levels of SOD and catalase were significantly higher and XOX activity was lower in MeDiet supplemented with extra-virgin olive oil and MeDiet supplemented with nuts than in the control group. Participants in both MeDiet groups showed higher plasma nitrate levels than in the control group. Adherence to the MeDiet showed a positive correlation with SOD and catalase plasma antioxidant activities.

CONCLUSION

A MeDiet enriched with either virgin olive oil or nuts enhances the plasma antioxidant capabilities and decreases XOX activity in patients with the metabolic syndrome but we did not observe changes in myeloperoxidase or markers of oxidative damage.

Elevated level of renal xanthine oxidase mRNA transcription after nephropathogenic infectious bronchitis virus infection in growing layers

To assess relationships between xanthine oxidase (XOD) and nephropathogenic infectious bronchitis virus (NIBV) infection, 240 growing layers (35 days old) were randomly divided into two groups (infected and control) of 120 chickens each. Each chicken in the control and infected group was intranasally inoculated with 0.2 mL sterile physiological saline and virus, respectively, after which serum antioxidant parameters and renal XOD mRNA expression in growing layers were evaluated at 8, 15 and 22 days post-inoculation (dpi). The results showed that serum glutathione peroxidase and superoxide dismutase activities in the infected group were significantly lower than in the control group at 8 and 15 dpi (p < 0.01), while serum malondialdehyde concentrations were significantly higher (p < 0.01). The serum uric acid was significantly higher than that of the control group at 15 dpi (p < 0.01). In addition, the kidney mRNA transcript level and serum activity of XOD in the infected group was significantly higher than that of the control group at 8, 15 and 22 dpi (p < 0.05). The results indicated that NIBV infection could cause the increases of renal XOD gene transcription and serum XOD activity, leading to hyperuricemia and reduction of antioxidants in the body.

Reproductive stage associated changes in plasma fatty acid profile and proinflammatory cytokine expression in rat mammary glands

Mastitis is a common disease for mammals all around the world. Figuring out why mastitis mainly occurs around parturition may be helpful for dealing with the disease. Lipolytic activity and oxidative stress take place around parturition, which may leads to alteration in fatty acids profile and proinflammatory cytokine expression. Thus, the aim of the present study was to further our understanding about the high incidence of mastitis around parturition by comparison of plasma fatty acid profile and mammary inflammation indicators at different reproductive stages. A total of 47 female rats were included in the present study. After mating, all the pregnant and non-pregnant rats began to receive the same experimental diet. Blood samples were collected at day 1 and 14 of gestation as well as day 3 postpartum. Mammary samples were collected at day 14 of gestation and day 3 postpartum from pregnant and non-pregnant rats. The results showed that rats at d 3 postpartum had greater (P < 0.05) plasma concentrations of non-esterified fatty acids (NEFA), arachidonic acid (ARA) and docosahexaenoic acid (DHA) as well as ARA: eicosapentaenoic acid (EPA) ratio than those at d 14 of gestation. The mRNA abundances of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), IL-8 and xanthine oxidoreductase (XOR) in mammary of the pregnant rats were greater (P < 0.05) than those in age-matched non-pregnant rats. Rats at d 3 postpartum had higher (P < 0.05) protein expression levels of IL-1β and TNF-α as well as meloperoxidase (MPO) activity and polymorphonuclear neutrophils (PMN) prevalence than those at d 1 of gestation. The rats at d 3 postpartum also had greater (P < 0.05) IL-1β and MPO activity than those at d 14 of gestation. The results indicated that elevated mammary expression of proinflammatory cytokines and XOR as well as altered fatty acid profile around parturition might facilitate the recruitment of neutrophils into mammary glands.

Mucosal production of uric acid by airway epithelial cells contributes to particulate matter-induced allergic sensitization

Exposure to particulate matter (PM), a major component of air pollution, contributes to increased morbidity and mortality worldwide. PM induces innate immune responses and contributes to allergic sensitization, although the mechanisms governing this process remain unclear. Lung mucosal uric acid has also been linked to allergic sensitization. The links among PM exposure, uric acid, and allergic sensitization remain unexplored. We therefore investigated the mechanisms behind PM-induced allergic sensitization in the context of lung mucosal uric acid. PM10 and house dust mite exposure selectively induced lung mucosal uric acid production and secretion in vivo, which did not occur with other challenges (lipopolysaccharide, virus, bacteria, or inflammatory/fibrotic stimuli). PM10-induced uric acid mediates allergic sensitization and augments antigen-specific T-cell proliferation, which is inhibited by uricase. We then demonstrate that human airway epithelial cells secrete uric acid basally and after stimulation through a previously unidentified mucosal secretion system. Our work discovers a previously unknown mechanism of air pollution-induced, uric acid-mediated, allergic sensitization that may be important in the pathogenesis of asthma.

Insight into the Salivary Gland Transcriptome of Lygus lineolaris (Palisot de Beauvois)

The tarnished plant bug (TPB), Lygus lineolaris (Palisot de Beauvois) is a polyphagous, phytophagous insect that has emerged as a major pest of cotton, alfalfa, fruits, and vegetable crops in the eastern United States and Canada. Using its piercing-sucking mouthparts, TPB employs a “lacerate and flush” feeding strategy in which saliva injected into plant tissue degrades cell wall components and lyses cells whose contents are subsequently imbibed by the TPB. It is known that a major component of TPB saliva is the polygalacturonase enzymes that degrade the pectin in the cell walls. However, not much is known about the other components of the saliva of this important pest. In this study, we explored the salivary gland transcriptome of TPB using Illumina sequencing. After in silico conversion of RNA sequences into corresponding polypeptides, 25,767 putative proteins were discovered. Of these, 19,540 (78.83%) showed significant similarity to known proteins in the either the NCBI nr or Uniprot databases. Gene ontology (GO) terms were assigned to 7,512 proteins, and 791 proteins in the sialotranscriptome of TPB were found to collectively map to 107 Kyoto Encyclopedia of Genes and Genomes (KEGG) database pathways. A total of 3,653 Pfam domains were identified in 10,421 sialotranscriptome predicted proteins resulting in 12,814 Pfam annotations; some proteins had more than one Pfam domain. Functional annotation revealed a number of salivary gland proteins that potentially facilitate degradation of host plant tissues and mitigation of the host plant defense response. These transcripts/proteins and their potential roles in TPB establishment are described.

Flavonoids and phenylethanoid glycosides from Lippia nodiflora as promising antihyperuricemic agents and elucidation of their mechanism of action

ETHNOPHARMACOLOGICAL RELEVANCE

Lippia nodiflora has been traditionally used in the Ayurvedic, Unani, and Sidha systems, as well as Traditional Chinese Medicine (TCM) for the treatment of knee joint pain, lithiasis, diuresis, urinary disorder and swelling.

AIM OF THE STUDY

The present study aims to investigate the antihyperuricemic effect of the L. nodiflora methanol extract, fractions, and chemical constituents and their mechanism of action in the rat model.

MATERIALS AND METHODS

The mechanisms were investigated by performing xanthine oxidase inhibitory, uricosuric, and liver xanthine oxidase/xanthine dehydrogenase (XOD/XDH) inhibitory studies in potassium oxonate- and hypoxanthine-induced hyperuricemic rats. The plant safety profile was determined using acute toxicity study. The molecular docking of the active compound to the xanthine oxidase was simulated using computer aided molecular modeling analysis.

RESULTS

Oral administration of methanol extract showed a dose-dependent reduction effect on the serum uric acid level of hyperuricemic rats. F3 was the most potent fraction in lowering the serum uric acid level of hyperuricemic rats. Bioactivity-guided purification of F3 afforded two phenylethanoid glycosides, arenarioside (1) and verbascoside (2) and three flavonoids, 6-hydroxyluteolin (3), 6-hydroxyluteolin-7-O-glycoside (4), and nodifloretin (5). The highest serum uric acid reduction effect was exhibited by 3 (66.94%) in hyperuricemic rats, followed by 5 (55.97%), 4 (49.16%), 2 (29.03%), and 1 (22.08%) at 0.2 mmol/kg. Dose-response investigation on 3 at doses of 0.05, 0.1, and 0.3 mmol/kg produced a significant dose-dependent reduction on the serum uric acid level of hyperuricemic rats. Repeated administration of F3 or 3 to the hyperuricemic rats for 10 continuous days resulted in a significant and progressive serum uric acid lowering effect in hyperuricemic rats. In contrast, methanol extract and F3 did not reduce serum uric acid level of normoruricemic rats. In addition, F4 significantly increased the uric acid excretion of hyperuricemic rats at 200mg/kg. No toxic effect was observed in rats administered with 5000 mg/kg of methanol extract or F3.

CONCLUSION

The potential application of L. nodiflora against hyperuricemia in the animal in accordance with its traditional uses has been demonstrated in the present study for the first time. The antihyperuricemic effect possessed by L. nodiflora was contributed mainly by liver XOD/XDH inhibitory activities and partially by uricosuric effect. Flavonoids mainly accountable for the uric acid lowering effect of L. nodiflora through the inhibition of XOD/XDH activities.

Xanthine oxidase injurious response in acute joint injury

BACKGROUND

While acute trauma is a major cause of osteoarthritis, its etiology is poorly understood. We sought to determine whether xanthine oxidase (XO), a major producer of reactive oxygen species, plays a role in the early events of acute joint injury.

METHODS

We analyzed synovial fluid from 23 subjects with recent severe acute knee injury. As a control we evaluated SF from 23 individuals with no or minimal knee osteoarthritis. We measured XO activity, reactive oxygen+reactive nitrogen species (ROS+RNS), protein oxidative damage (carbonyl), the type II collagen synthesis marker procollagen II c-propeptide (CPII) and the type II collagen degradation marker collagen type II telopeptide (CTx-II). We also measured the proinflammatory cytokine IL-6.

RESULTS

XO and ROS+RNS were higher (p=0.02 and p=0.001 respectively) in acute injury than control and were strongly positively associated (r=0.62, p=0.004). Carbonyl was higher in acute injury than control (p=0.0002) and was positively correlated with XO (r=0.68, p=0.0007) as well as with ROS+RNS (r=0.71, p=0.004). CPII was higher in acute injury than control (p<0.0001) and was negatively correlated with XO (r=-0.49, p=0.017). While CTxII was not significantly higher in acute injury than control, it was positively correlated with CPII (r=0.71, p=0.0002). IL-6 was higher in acute injury than control (p<0.0001).

CONCLUSIONS

These results are consistent with a potentially injurious effect of XO activity in acute joint injury characterized by excess free radical production and oxidative damage. These effects are associated with an inhibition of type II collagen production that may impede the ability of the injured joint to repair.

Breastmilk-Saliva Interactions Boost Innate Immunity by Regulating the Oral Microbiome in Early Infancy

INTRODUCTION

Xanthine oxidase (XO) is distributed in mammals largely in the liver and small intestine, but also is highly active in milk where it generates hydrogen peroxide (H2O2). Adult human saliva is low in hypoxanthine and xanthine, the substrates of XO, and high in the lactoperoxidase substrate thiocyanate, but saliva of neonates has not been examined.

RESULTS

Median concentrations of hypoxanthine and xanthine in neonatal saliva (27 and 19 μM respectively) were ten-fold higher than in adult saliva (2.1 and 1.7 μM). Fresh breastmilk contained 27.3 ± 12.2 μM H2O2 but mixing baby saliva with breastmilk additionally generated >40 μM H2O2, sufficient to inhibit growth of the opportunistic pathogens Staphylococcus aureus and Salmonella spp. Oral peroxidase activity in neonatal saliva was variable but low (median 7 U/L, range 2-449) compared to adults (620 U/L, 48-1348), while peroxidase substrate thiocyanate in neonatal saliva was surprisingly high. Baby but not adult saliva also contained nucleosides and nucleobases that encouraged growth of the commensal bacteria Lactobacillus, but inhibited opportunistic pathogens; these nucleosides/bases may also promote growth of immature gut cells. Transition from neonatal to adult saliva pattern occurred during the weaning period. A survey of saliva from domesticated mammals revealed wide variation in nucleoside/base patterns.

DISCUSSION AND CONCLUSION

During breast-feeding, baby saliva reacts with breastmilk to produce reactive oxygen species, while simultaneously providing growth-promoting nucleotide precursors. Milk thus plays more than a simply nutritional role in mammals, interacting with infant saliva to produce a potent combination of stimulatory and inhibitory metabolites that regulate early oral-and hence gut-microbiota. Consequently, milk-saliva mixing appears to represent unique biochemical synergism which boosts early innate immunity.

The effect of allopurinol administration on mitochondrial respiration and gene expression of xanthine oxidoreductase, inducible nitric oxide synthase, and inflammatory cytokines in selected tissues of broiler chickens

Birds have a remarkable longevity for their body size despite an increased body temperature, higher metabolic rate, and increased blood glucose concentrations compared to most mammals. As the end-product of purine degradation, uric acid (UA) is generated in the xanthine/hypoxanthine reactions catalyzed by xanthine oxidoreductase (XOR). In the first study, Cobb × Cobb broilers (n = 12; 4 weeks old) were separated into 2 treatments (n = 6); control (CON) and allopurinol (AL) 35 mg/kg BW (ALLO). The purpose of this study was to assess mitochondrial function in broiler chickens in response to potential oxidative stress generated from the administration of AL for 1 wk. There was a significant reduction in state 3 respiration (P = 0.01) and state 4 respiration (P = 0.007) in AL-treated birds compared to the controls. The purpose of the second study was to assess the effect of AL on gene expression of inflammatory cytokines interferon-γ (IFN)-γ, IL-1β, IL-6, and IL-12p35, as well as inducible nitric oxide synthase and XOR in liver tissue. Cobb × Cobb broilers were separated into two groups at 4 wk age (n = 10); CON and ALLO. After 1 wk AL treatment, half of the birds in each group (CON 1 and ALLO 1) were euthanized while the remaining birds continued on AL treatment for an additional week (CON 2 and ALLO 2). A significant increase in gene expression of XOR, IFN-γ, IL-1β, and IL-12p35 in ALLO 2 birds as compared to birds in CON 2 was detected. Liver UA content was significantly decreased in both ALLO 1(P = 0.003) and ALLO 2 (P = 0.012) birds when compared to CON 1 and CON 2, respectively. The AL reduced liver UA concentrations and increased expression of inflammatory cytokines. Additional studies are needed to determine if AL causes a direct effect on mitochondria or if mitochondrial dysfunction observed in liver mitochondria was due indirectly through increased oxidative stress or increased inflammation.

The C-terminal peptide plays a role in the formation of an intermediate form during the transition between xanthine dehydrogenase and xanthine oxidase

Mammalian xanthine oxidoreductase can exist in both dehydrogenase and oxidase forms. Conversion between the two is implicated in such diverse processes as lactation, anti-bacterial activity, reperfusion injury and a growing number of diseases. We have constructed a variant of the rat liver enzyme that lacks the carboxy-terminal amino acids 1316-1331; it appears to assume an intermediate form, exhibiting a mixture of dehydrogenase and oxidase activities. The purified variant protein retained ~ 50-70% of oxidase activity even after prolonged dithiothreitol treatment, supporting a previous prediction that the C-terminal region plays a role in the dehydrogenase to oxidase conversion. In the crystal structure of the protein variant, most of the enzyme stays in an oxidase conformation. After 15 min of incubation with a high concentration of NADH, however, the corresponding X-ray structures showed a dehydrogenase-type conformation. On the other hand, disulfide formation between Cys535 and Cys992, which can clearly be seen in the electron density map of the crystal structure of the variant after removal of dithiothreitol, goes in parallel with the complete conversion to oxidase, resulting in structural changes identical to those observed upon proteolytic cleavage of the linker peptide. These results indicate that the dehydrogenase-oxidase transformation occurs rather readily and the insertion of the C-terminal peptide into the active site cavity of its subunit stabilizes the dehydrogenase form. We propose that the intermediate form can be generated (e.g. in endothelial cells) upon interaction of the C-terminal peptide portion of the enzyme with other proteins or the cell membrane.

DATABASE

Coordinate sets and structure factors for the four crystal structures reported in the present study have been deposited in the Protein Data Bank under the identification numbers 4YRW, 4YTZ, 4YSW, and 4YTY.