Induction of nitric oxide synthase in macrophages: inhibition by fructose-1,6-diphosphate

Yinhuang buccal tablet alters airway microbiota composition and metabolite profile in healthy humans

ETHNOPHARMACOLOGICAL RELEVANCE

Perturbations in airway microbiota composition and disruption of microbe-metabolite interactions have been observed in respiratory infectious diseases (RIDs). The Yinhuang (YH) buccal tablet, as an ancient Chinese medicinal formula, has been traditionally employed for the management of upper RIDs. However, there is a lack of evidence for the effects of YH buccal tablets on upper respiratory tract microbiota and circulating metabolites.

AIM OF THE STUDY

The aim of this study was to analyze the changes in respiratory microbiota composition and circulating metabolite profile after YH buccal tablets administration.

MATERIALS AND METHODS

Throat swab samples and serum samples were collected from 60 healthy subjects for high-throughput 16S ribosomal RNA gene (16S rRNA) sequencing and non-targeted Ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis.

RESULTS

Airway microbial composition changed significantly after YH administration. The abundance of Actinomyces and Prevotella_7 increased, while the abundance of potentially pathogenic Pseudomonas and Corynebacterium decreased. A total of 168 significant HMDB taxonomic metabolites were identified in serum samples, of which lipid metabolites accounted for the largest proportion. Correlation analysis showed that circulatory metabolites were significantly correlated with changes in airway microbiota composition.

CONCLUSIONS

YH buccal tablets can inhibit opportunistic pathogens, increase beneficial microorganisms in the upper respiratory tract, and regulate the body's metabolic pathways. These findings provide insights into the mechanism of action of YH buccal tablets in the treatment and prevention of respiratory diseases.

Comparison of lactoferrin activity in fresh and stored human milk

OBJECTIVE

Lactoferrin (Lf), the dominant protein in human milk (HM), has been shown to have anti-inflammatory and anti-microbial activity in the neonatal gut. Previous studies indicate that freezing significantly decreases the concentration of Lf in HM. The objective of our study was to compare the activity of Lf in fresh and frozen HM over time.

STUDY DESIGN

HM samples were examined fresh and after storage at -20 °C for 3 and 6 months. Lf concentration was determined by enzyme-linked immunoassay, and the activity was measured by examination of nitric oxide (NO) production and tumor necrosis factor-α secretion from rat macrophages exposed to HM samples.

RESULT

After 3 and 6 months at -20 °C, the average decrease in Lf concentrations was 55% and 65%, respectively. The bioactivity of Lf also decreased significantly over 6 months.

CONCLUSION

Freezing HM for 3 or more months significantly decreases Lf levels and activity. Periodically providing fresh HM may benefit vulnerable preterm neonates.

Glycolysis, tumor metabolism, cancer growth and dissemination. A new pH-based etiopathogenic perspective and therapeutic approach to an old cancer question

Cancer cells acquire an unusual glycolytic behavior relative, to a large extent, to their intracellular alkaline pH (pHi). This effect is part of the metabolic alterations found in most, if not all, cancer cells to deal with unfavorable conditions, mainly hypoxia and low nutrient supply, in order to preserve its evolutionary trajectory with the production of lactate after ten steps of glycolysis. Thus, cancer cells reprogram their cellular metabolism in a way that gives them their evolutionary and thermodynamic advantage. Tumors exist within a highly heterogeneous microenvironment and cancer cells survive within any of the different habitats that lie within tumors thanks to the overexpression of different membrane-bound proton transporters. This creates a highly abnormal and selective proton reversal in cancer cells and tissues that is involved in local cancer growth and in the metastatic process. Because of this environmental heterogeneity, cancer cells within one part of the tumor may have a different genotype and phenotype than within another part. This phenomenon has frustrated the potential of single-target therapy of this type of reductionist therapeutic approach over the last decades. Here, we present a detailed biochemical framework on every step of tumor glycolysis and then proposea new paradigm and therapeutic strategy based upon the dynamics of the hydrogen ion in cancer cells and tissues in order to overcome the old paradigm of one enzyme-one target approach to cancer treatment. Finally, a new and integral explanation of the Warburg effect is advanced.

Fructose-1,6-bisphosphate ameliorates lipopolysaccharide-induced dysfunction of blood-brain barrier

Fructose-1,6-bisphosphate (FBP), a glycolytic intermediate, has neuroprotective effects in various brain injury models. However, its effects on blood-brain barrier (BBB) are largely unknown. In this study, we investigated the effects of FBP on lipopolysaccharide (LPS)-induced BBB dysfunction in in vitro BBB model comprising co-culture of mouse brain endothelial cell line, bEnd.3 and mouse primary astrocyte and explored its action mechanism therein involved. LPS induced the impairment of endothelial permeability and transendothelial electrical resistance (TEER). The functional changes were confirmed by alterations in immunostaining for junctional proteins occludin, ZO-1 and VE-cadherin, such as the loss of cortical staining pattern and appearance of intercellular gaps in endothelial cells. Co-administration of FBP alleviated the deleterious effects of LPS on BBB permeability and TEER in a dose dependent manner. And also FBP inhibited the LPS-induced changes in the distribution of endothelial junctional proteins, resulting in the better preservation of monolayer integrity. FBP suppressed the production of reactive oxygen species (ROS) but did not affect cyclooxygenase-2 expression and prostaglandin E₂ production in endothelial cells stimulated with LPS. Taken together, these data suggest that FBP could ameliorate LPS-induced BBB dysfunction through the maintenance of junctional integrity, which might be mediated by downregulation of ROS production.

Nitric oxide as a mediator of fructose 1,6-bisphosphate protection in galactosamine-induced hepatotoxicity in rats

Fructose 1,6-bisphosphate (F1,6BP) has been widely used as a therapeutic agent for different harmful conditions in a variety of tissues. The hypothesis of the present work was that the increase in nitric oxide production and the prevention of oxidative stress induced by exogenous F1,6BP mediate its protective effect against the hepatotoxic action of GalN. Experimental groups used were sham, F1,6BP (2g/kg bw i.p.), GalN (0.4g/kg bw i.p), l-NAME (10mg/kg bw i.v.), F1,6BP+GalN, l-NAME+GalN and l-NAME+F1,6BP+GalN. Animals were killed after 24h of bolus administration. F1,6BP induced an increase in NO and the redox ratio (GSH/GSSG) in liver. Western blot assays pointed to overexpression of liver eNOS in F1,6BP-treated rats. The hepatic injury induced by GalN increased transaminases in plasma and decreased the reduced/oxidized glutathione ratio in liver. The concomitant administration of F1,6BP reversed this damage, while the addition of l-NAME worsened the liver injury. We provided evidence that this F1,6BP-induced protection may be related to the increase in NO production through the positive modulation of eNOS, and the increase in intracellular reduced glutathione, thus providing a higher reducing capacity.

Fructose-1,6-bisphosphate attenuates induction of nitric oxide synthase in microglia stimulated with lipopolysaccharide

AIMS

Fructose-1,6-bisphosphate (FBP) is a glycolytic intermediate with neuroprotective action in various brain injury models. However, the mechanism underlying the neuroprotection of FBP has not been fully defined. In this study, we investigated whether FBP inhibits endotoxin-induced nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression in microglial cells and explored the possible mechanisms of the effects of FBP.

MAIN METHODS

Murine microglial cell line BV2 and primary cultured murine microglial cells were used. NO production and iNOS expression were determined by Griess reaction, RT-PCR and Western blot. Luciferase assay using iNOS promoter-luciferase (iNOS-Luc) construct was adopted for measuring transcriptional activity.

KEY FINDINGS

FBP dose-dependently suppressed lipopolysaccharide (LPS)-induced NO production, along with reducing the expression of iNOS at both the protein and mRNA level in primary cultured murine microglia and BV2 cells. FBP significantly inhibited iNOS promoter activity but stabilized iNOS mRNA. Among transcription factors known to be related to iNOS expression, activator protein (AP-1) activation was significantly blocked by FBP. FBP suppressed LPS-induced phosphorylation of three MAPK subtypes-p38 MAPK, JNK and ERK. FBP inhibited LPS-induced production of reactive oxygen species (ROS) and decreased intracellular GSSG/GSH ratio.

SIGNIFICANCE

Our findings suggest that FBP attenuates the LPS-induced iNOS expression through inhibition of JNK and p38 MAPK, which might be related to ROS downregulation.

Fructose-1,6-bisphosphate inhibits in vitro and ex vivo platelet aggregation induced by ADP and ameliorates coagulation alterations in experimental sepsis in rats

Sepsis is a systemic response to an infection that leads to a generalized inflammatory reaction. There is an intimate relationship between procoagulant and proinflammatory activities, and coagulation abnormalities are common in septic patients. Pharmaceutical studies have focused to the development of substances that act on coagulation abnormalities and on the link between coagulation and inflammation. Fructose-1,6-bisphosphate (FBP) is a high-energy glycolitic metabolite that in the past two decades has been shown therapeutic effects in great number of pathological situations, including sepsis. The aims of this study were to assess the effects of FBP on platelet aggregation in vitro and ex vivo in healthy and septic rats and evaluate the use of FBP as a treatment for thrombocytopenia and coagulation abnormalities in abdominal sepsis in rat. FBP inhibited platelet aggregation (P < 0.001) in vitro in healthy rats from the smallest dose tested, 2.5 mM, in a dose-dependent manner. The mean effective dose calculated was 10.6 mM. The highest dose tested, 40 mM, completely inhibited platelet aggregation (P < 0.001) induced by ADP. Platelet aggregation in plasma from septic rats was inhibited only with higher doses of FBP, starting from 20 mM (P < 0.001). The calculated mean effective dose was 19.3 mM. Ex vivo platelet aggregation in septic rats was significantly lower (P < 0.05) than healthy rats and the treatment with FBP, at the dose of 2 g/kg, diminished the platelet aggregation at the extension of 27% (P < 0.001), suggesting that FBP is a potent platelet aggregation inhibitor in vivo. Moreover, treatment with FBP 2 g/kg prevented thrombocytopenia (P < 0.001), prolongation of prothrombin and partial thromboplastin time (P < 0.001), but not fibrinogen, in septic rats. The most important findings in this study are that FBP is a potent platelet aggregation inhibitor, in vitro and ex vivo. It presents protective effects on coagulation abnormalities, which can represent a treatment against DIC. The mechanisms for these effects remain under investigation.

Fructose 1,6-Diphosphate Alleviates UV-Induced Oxidative Skin Damage in Hairless Mice

Reactive oxygen species (ROS) are involved in the deleterious effects of UV light on skin. The antioxidant defense system is considered to be crucial for protecting skin from ROS. Recently, we showed that fructose 1,6-diphosphate (FDP), a glycolytic metabolite, reduced oxidative stress in UVB-irradiated keratinocytes. This study set out to determine whether topically applied FDP could exert protective effects against UV-induced skin damage in hairless mice. An in vitro skin permeation study using Franz-type diffusion cells showed that the amount of [14C]-FDP that diffused through the skin increased in a time-dependent manner, and about 3.5% of the applied FDP penetrated the skin after 24 h. Topical application of FDP (1%) preserved the endogenous antioxidant capacity of skin such as catalase and glutathione, which were significantly reduced after UVB irradiation without FDP. FDP also reversed the loss of catalase protein and prevented the accumulation of carbonylated proteins induced by UVB irradiation. These results provide evidence that topically administered FDP could penetrate into the skin and attenuate UVB-induced oxidative skin damage in hairless mice.

Effect of normothermic perfusion using fructose-1,6-bisphosphate for maintenance of liver function during in situ extended hepatectomy by the total hepatic vascular exclusion technique

BACKGROUND

Recently, hepatic surgery has made remarkable progress, and it is important to use appropriate liver perfusion. We evaluated the effect of normothermic liver perfusion with the addition of fructose-1, 6-bisphosphate (FBP) and oxygenation to maintain liver parenchymal, non-parenchymal, and Kupffer cell function.

MATERIALS AND METHODS

The rats were divided into five groups according to the perfusate and continuous perfusion was performed: Control group = 4 degrees C lactate Ringer with 10% glucose (LRG) solution; normothermic group = 25 degrees C LRG solution; normothermic oxygenated group = 25 degrees C oxygenated LRG solution; normothermic FBP group = 25 degrees C LRG solution with addition of 10 mmol/L FBP; normothermic oxygenated FBP group = 25 degrees C oxygenated LRG solution with addition of 10 mmol/L FBP. Parameters under evaluation were oxygen consumption, liver energy level (adenosine triphosphate, total adenine nucleotide), glutathione, lipid peroxide, hyaluronic acid uptake ratio, apoptosis, and histomorphology. Moreover, we studied the effect of FBP and normothermia on Kupffer cells activation in vitro.

RESULTS

Liver energy level was lower in the normothermic group than the control group. But, it was improved by oxidation or addition of FBP, and it was satisfactorily maintained up to 120 min in the group with normothermic oxygenated FBP. Hyaluronic acid uptake was maintained highly at all times as measured in normothermic oxygenated FBP group. The uptake of lipopolysaccharide was significantly higher as a result of adding FBP, compared with that in the control group and the normothermic group. Moreover, the apoptotic index in the liver was decreased in normothermic FBP group compared to control group.

CONCLUSIONS

The normothermic liver perfusion under additional FBP and oxygenation protects both parenchymal and non-parenchymal cells from reperfusion injury.

Neuroprotection by fructose-1,6-bisphosphate involves ROS alterations via p38 MAPK/ERK

Fructose-1,6-bisphosphate (FBP) is a glucose metabolism intermediate that shows a neuroprotective action in animal models of ischemia and other injuries. The intracellular mechanism of FBP on neuroprotection has not been previously defined. Here, we examined whether FBP has a neuroprotective effect against excitotoxicity, and whether it affects the production of reactive oxygen species (ROS), which are involved in the MAPK pathway in cortical neurons. FBP prevented neuronal death in a dose-dependent manner following 24 h of treatment with the excitotoxin, NMDA. After 8 h of NMDA treatment, we observed FBP-induced inhibition of the production of intracellular ROS, and at the earlier time FBP suppressed NMDA-induced p-p38 and p-ERK expression. In addition, MAPK inhibitors reduced NMDA-induced excitotoxicity and also ROS production. Taken together, our results suggest that the neuroprotective effects of FBP could be explained by down-regulation of free radical production through the p38MAPK/ERK pathway.

Fructose-1,6-diphosphate attenuates prostaglandin E2 production and cyclo-oxygenase-2 expression in UVB-irradiated HaCaT keratinocytes

1. Fructose-1,6-diphosphate (FDP), a glycolytic metabolite, is reported to ameliorate inflammation and inhibit the nitric oxide production in murine macrophages stimulated with endotoxin. It is also reported that FDP has cytoprotective effects against hypoxia or ischaemia/reperfusion injury in brain and heart. However, underlying mechanisms of its various biological activities are not completely understood. 2. In this study, we examined the effects of FDP on UVB-induced prostaglandin production in HaCaT keratinocytes. 3. Ultraviolet B (UVB, 280-320 nm) irradiation (30 mJ cm(-2)) increased prostaglandin E(2)(PGE(2)) production, which was significantly decreased by FDP in a concentration dependent manner. NS-398, a cyclo-oxygenase-2 (COX-2) selective inhibitor completely inhibited UVB-induced PGE(2) production showing that COX-2 activity is responsible for the increase in PGE(2) production under our experimental conditions. 4. UVB irradiation increased total COX activity and COX-2 mRNA in HaCaT keratinocytes, which were significantly blocked by FDP in a concentration dependent manner. 5. N-acetylcysteine (NAC) significantly attenuated UVB-induced PGE(2) production, COX activity and COX-2 mRNA expression indicating oxidative components might contribute to these events. 6. FDP reduced UVB-induced increase in cellular reactive oxygen species (ROS) level although it did not show direct radical scavenging effect in the experiment using 1,1-diphenyl-2picrylhydrazil (DPPH). FDP preserved the cellular antioxidant capacity including catalase activity and GSH content after irradiation. 7. Our data obtained hitherto suggest that FDP may have a protective role in UVB-injured keratinocyte by attenuating PGE(2) production and COX-2 expression, which are possibly through blocking intracellular ROS accumulation.

Storage solution containing fructose-1,6-bisphosphate inhibits the excess activation of Kupffer cells in cold liver preservation

BACKGROUND

In liver transplantation, the activation of Kupffer cells at the time of cold preservation and reperfusion is considered to play an important role. In the present study, the usefulness of cold storage solution containing fructose-1,6-bisphosphate (FBP) was compared with University of Wisconsin (UW) solution in the function of Kupffer cells.

METHODS

Kupffer cells were separated from rat liver stored at 4 degrees C in each storage solution. Four kinds of storage solutions were used: UW, simplified UW without FBP (0-FBP), and solutions with 10 or 20 mM FBP (10-FBP, 20-FBP). Lipopolysaccharide (LPS) labeled by fluorescein was loaded after 12 or 24 hr of cold preservation in each solution. The rates of cells uptaking LPS as phagocytic ability were measured using flow cytometry. Tumor necrosis factor-alpha, cytokine-induced neutrophil chemoattractant, and nitric oxide (NO) were measured in the supernatant.

RESULTS

Tumor necrosis factor-alpha values in the 20-FBP group were significantly lower than those in the UW group. Cytokine-induced neutrophil chemoattractant values at 60 min after loading LPS were significantly lower in the 20-FBP group than in the UW group. NO values at 24 hr after loading LPS were significantly lower in the 20-FBP group compared with the UW group. The 20-FBP group was highest in the rates of cells uptaking LPS after 24-hr cold preservation.

CONCLUSIONS

The storage solution containing FBP controlled the secretion of cytokines and NO from Kupffer cells and maintained phagocytic ability. This solution was considered to be more useful than UW solution for Kupffer cell protection.

Physiopathological studies in septic rats and the use of fructose 1,6-bisphosphate as cellular protection

OBJECTIVE

The aim of this research project was to test the ability of fructose 1,6-bisphosphate (FBP), which has anti-inflammatory effects and maintains cellular energy levels, to inhibit the septic process in an experimental model in rats.

DESIGN

Prospective, controlled animal trial.

SETTING

Research laboratory.

SUBJECTS

Fed male Wistar rats.

INTERVENTIONS

Three experimental groups were formed for the test: control group, untreated septic group, and septic group treated with FBP (500 mg/kg).

MEASUREMENTS AND MAIN RESULTS

In the control group, there were no deaths; in the untreated septic group, the mortality rate was 100% within 15 hrs; in the septic group treated with FBP, the mortality rate reached 20% within 15 hrs. The blood cell tests revealed that concentrations of hematocrit, leukocytes, monocytes, and immature cells increased significantly in the untreated septic group compared with both the FBP-treated septic group and the control group. The histologic lesions verified in the heart, lungs, liver, and kidneys of septic animals were smaller and even absent in those treated with FBP.

CONCLUSION

FBP reduced the mortality rate provoked by experimental sepsis and ameliorated hematologic and histologic alterations.

Lactoferrin protects neonatal rats from gut-related systemic infection

Lactoferrin is a milk protein that reportedly protects infants from gut-related, systemic infection. Proof for this concept is limited and was addressed during in vivo and in vitro studies. Neonatal rats pretreated orally with recombinant human lactoferrin (rh-LF) had less bacteremia and lower disease severity scores (P < 0.001) after intestinal infection with Escherichia coli. Control animals had 1,000-fold more colony-forming units of E. coli per milliliter of blood than treated animals (P < 0.001). Liver cultures from control animals had a twofold increase in bacterial counts compared with cultures from rh-LF-treated pups (P < 0.02). Oral therapy with rh-LF + FeSO(4) did not alter the protective effect. In vitro studies confirmed that rh-LF interacted with the infecting bacterium and rat macrophages. An in vitro assay showed that rh-LF did not kill E. coli, but a combination of rh-LF + lysozyme was microbicidal. In vitro studies showed that rat macrophages released escalating amounts of nitric oxide and tumor necrosis factor-alpha when stimulated with increasing concentrations of rh-LF. The in vitro studies suggest that rh-LF may act with other "natural peptide antibiotics" or may prime macrophages to kill E. coli in vivo.

Effect of fructose-1, 6-diphosphate versus diphenhydramine on mortality in compound 48/80-induced shock

Fructose-1,6-diphosphate (FDP) has a salutary effect on hemorrhagic, traumatic and endotoxic shock. The role of FDP on compound 48/80-induced shock was therefore investigated. Sprague Dawley aged male rats (448+/-7.4 gm body weight) were randomly assigned into three groups and treated intraperitoneally with diphenhydramine (DPHM) 15 mg/kg (n=11), 12.5 ml of 10% FDP (n=10) and 12.5 ml saline (n=10). The rats were injected with compound 48/80 (5 mg/kg) 30 min later, and monitored every 10 min for 60 min. Arterial pressure was higher in FDP rats than in DPHM (P<0.01) or saline (P<0.005) groups. Plasma potassium (K(+)) was lower in the FDP group (P<0.01). Arterial pO2 and pCO2 were within physiological range in all groups. A profound decrease in arterial pH and bicarbonate (HCO3(-)) was also observed in all groups. Mortality at 48 h in the saline group was 100%, in the DPHM group 91%, and in the FDP group 20% (P<0.001 and P<0.005, respectively). FDP improved survival significantly in this study.