The effect of lipopolysaccharide on the disposition of xanthines in rats

Effect of You-Gui-Wan on House Dust Mite-Induced Mouse Allergic Asthma via Regulating Amino Acid Metabolic Disorder and Gut Dysbiosis

Chinese herbal remedies have long been used for enhancing immunity and treating asthma. However, the evidence-based efficacy remains to be supported. This study aimed to explore the potential bio-signatures in allergic asthma and the effect of You-Gui-Wan (YGW), a traditional Chinese herbal prescription, on dust mite-induced mouse allergic asthma. Extract of Dermatophagoides pteronyssinus (Der p), a dust mite, was intratracheally administered to induce allergic asthma in mice. Serum metabolomic and 16S rRNA-based microbiome profiling were used to analyze untargeted metabolites with levels significantly changed and gut microbiota composition, respectively. Results indicated that 10 metabolites (acetylcarnitine, carnitine, hypoxanthine, tryptophan, phenylalanine, norleucine, isoleucine, betaine, methionine, and valine), mainly associated with branched-chain amino acid (BCAA) metabolism, aromatic amino acid (AAA) biosynthesis, and phenylalanine metabolism were markedly elevated after Der p treatment. YGW administration reversed the levels for 7 of the 10 identified metabolites, chiefly affecting BCAA metabolism. On 16S DNA sequencing, disordered Der p-induced gut microbiota was significantly alleviated by YGW. Multiple correlation analysis showed a good correlation between gut microbiota composition and levels of selected metabolites. Our study showed YGW administration effectively alleviated BCAA metabolic disorder and improved gut dysbiosis. This study provides support for YGW administration with benefits for allergic asthma.

Lack of effect of aciclovir on metabolism of theophylline and expression of hepatic cytochrome P450 1A2 in rats

There is an interesting clinical report indicating that aciclovir, which is mainly excreted into urine, decreases the systemic clearance of theophylline by inhibiting cytochrome P450 (CYP) 1A2-mediated metabolism. In this study, we investigated the effect of aciclovir on the metabolism of theophylline, and on the activity and expression of hepatic CYP1A2 in rats. Theophylline (10 mg/kg) was injected intravenously into rats treated with two different dosages of aciclovir. When theophylline was simultaneously administered with aciclovir (50 mg/kg), the systemic clearance of theophylline and metabolic clearance of its major metabolites, 1-methyluric acid and 1,3-dimethyluric acid, were unchanged. In place of theophylline, when 1-methyl-3-propylxanthine (2.5 mg/kg), which is almost metabolized by CYP1A2 in rats, was coadministered intravenously with aciclovir (50 mg/kg), the pharmacokinetics of 1-methyl-3-propylxanthine was also unchanged. When theophylline was administered to rats pretreated with repeated intraperitoneal injections of aciclovir (25 mg/kg twice daily for 3 d), no significant differences in the systemic clearance of theophylline and its metabolic clearance to 1-methyluric acid and 1,3-dimethyluric acid were observed between the control and aciclovir-treated rats. This dosage of aciclovir did not change the activity of 7-ethoxyresorufin O-dealkylation, which is represented as CYP1A2 activity. In Western blot analysis, no significant change in the protein levels of hepatic CYP1A2 was observed between the control and aciclovir-treated rats. The present study suggests that aciclovir has no effect on the pharmacokinetics and metabolism of theophylline and on the activity and expression of hepatic CYP1A2 in rats.

Effects of bacterial lipopolysaccharide on the pharmacokinetics of DA-7867, a new oxazolidinone, in rats

Pharmacokinetic parameters of DA-7867 were compared after intravenous and oral administration at a dose of 10 mg/kg to control rats and rats pretreated with Klebsiella pneumoniae lipopolysaccharide (KPLPS). After intravenous administration of DA-7867 at a dose of 10 mg/kg to 10 rats, metabolism of DA-7867 was minimal; however, the urinary and gastrointestinal excretion of DA-7867 were approximately 85% of intravenous dose when collected for up to 14 days. After intravenous administration to rats pretreated with KPLPS, the AUC was significantly greater (14,100 versus 9810 microg x min/mL), and this could be due to significantly slower total body clearance (CL, 0.709 versus 1.02 mL/min/kg). The slower CL in the rats could be due to significantly smaller fecal excretion of DA-7867 for up to 14 days (41.1 versus 58.8% of intravenous dose of DA-7867) because urinary excretion of DA-7867 was not significantly different between two groups of rats. After oral administration, the AUC values were not significantly different between two groups of rats and this was mainly due to decrease in absorption from the gastrointestinal tract in rats pretreated with the KPLPS (approximately 82 and 95% of oral dose were absorbed for rats with KPLPS and control rats, respectively).

Systemic Inflammation-Associated Glucocorticoid Resistance and Outcome of ARDS

Dysregulated systemic inflammation with excess activation of pro-inflammatory transcription factor nuclear factor-kappaB (NF-kappaB)-activated by inflammatory signals-compared to the anti-inflammatory transcription factor glucocorticoid receptor-alpha (GRalpha)-activated by endogenous or exogenous glucocorticoids (GCs)-is an important pathogenetic mechanism for pulmonary and extrapulmonary organ dysfunction in patients with acute respiratory distress syndrome (ARDS). Activation of one transcription factor in excess of the binding (inhibitory) capacity of the other shifts cellular responses toward increased (dysregulated) or decreased (regulated) transcription of inflammatory mediators over time. Recent data indicate that failure to improve in ARDS (unresolving ARDS) is frequently associated with failure of the activated GRs to downregulate the transcription of inflammatory cytokines despite elevated levels of circulating cortisol, a condition defined as systemic inflammation-associated acquired GC resistance; it is potentially reversible with prolonged GC supplementation. In the first part of this paper, after a brief description of inflammation in ARDS and our model of translational research, we review the two cellular signaling pathways that are central to the regulation of inflammation-the stimulatory NF-alphaB and the inhibitory GRalpha. In the second part, we review findings of recent studies indicating that excessive inflammatory activity in patients with unresolving ARDS may induce noncompensated GC resistance in target organs. In the third part, we review factors affecting cellular response to GC and potential mechanisms involved in inflammation-associated GC resistance.

Effect of endotoxin on doxorubicin transport across blood-brain barrier and P-glycoprotein function in mice

The aim of this study was to investigate whether Klebsiella pneumoniae endotoxin modifies transport of doxorubicin, a P-glycoprotein substrate, across the blood-brain barrier and P-glycoprotein function in mice. Doxorubicin (30 mg/kg) was administered into the tail vein or fluorescein isothiocyanate-labeled dextran (FD-4) was infused (20 microg/min) into the right jugular vein of mice intravenously injected with endotoxin (10 mg/kg) 6 or 24 h earlier. Blood and brain samples were collected 4 h after injection of doxorubicin or 1 h after infusion of FD-4. We examined using Western blotting the influence of endotoxin on the expression of P-glycoprotein in brains obtained 6, 12 and 24 h after injection. Endotoxin did not change the plasma and brain concentrations and brain-to-plasma concentration ratio (K(p) value) of FD-4. No histopathological changes in brain capillaries were observed. These results suggest that endotoxin does not cause damage to brain capillaries. Plasma and brain concentrations of doxorubicin in mice treated 6 h earlier with endotoxin were significantly higher than those in control and mice treated 24 h earlier. However, endotoxin did not significantly change the K(p) value of doxorubicin. The protein level of P-glycoprotein was significantly, but slightly down-regulated 6 h after endotoxin treatment. However, the levels remained almost unchanged after 12 and 24 h. The present results suggest that Klebsiella pneumoniae endotoxin has no effect on the brain capillary integrity and doxorubicin transport across the blood-brain barrier in mice. It is likely that P-glycoprotein function might be sufficient to transport doxorubicin in spite of decreased levels of P-glycoprotein in the brain.

Shiga-like toxin II derived from Escherichia coli O157:H7 modifies renal handling of levofloxacin in rats

The effect of Shiga-like toxin II (SLT-II) (2 microg/animal), which was derived from Escherichia coli O157:H7, on renal handling of levofloxacin (LVX), a model drug for quinolone antimicrobial agents, was investigated in rats 24 h after intravenous injection. In histopathological examination, acute tubular injury was observed in SLT-II-treated rats, but the glomeruli were not injured. SLT-II significantly increased the steady-state concentration of LVX in plasma to 1.5-fold that of control rats. SLT-II induced significant decreases in the glomerular filtration rate (GFR) and renal clearance (CL(R)) of LVX. SLT-II slightly, but significantly, increased the unbound fraction and decreased renal plasma flow with no change in the extraction ratio of p-aminohippurate. SLT-II significantly increased concentrations of tumor necrosis factor alpha (TNF-alpha) and nitrite and nitrate (NOx) in plasma. The TNF-alpha inhibitor pentoxifylline partly, but significantly, inhibited SLT-II-induced decreases in the GFR and CL(R) of LVX; in contrast, S-methylisothiourea, a selective inhibitor of inducible nitric oxide synthase, did not. Western blotting analysis revealed that SLT-II did not alter the levels of multidrug resistance-associated protein 2 (Mrp2) and P-glycoprotein in kidneys 24 h after injection, assuming the lack of involvement of Mrp2 and P-glycoprotein in SLT-II-induced acute renal tubular injury and renal handling of LVX observed 24 h after SLT-II injection. The present study suggests that SLT-II impairs the renal handling of LVX by decreasing GFR and causing decreased renal plasma flow.

Time-variant increase in methylprednisolone clearance in patients with acute respiratory distress syndrome: a population pharmacokinetic study

Methylprednisolone (MP) disposition was evaluated in 20 individuals who participated in an ongoing randomized, double-blind, placebo-controlled study designed to evaluate the efficacy of MP in the treatment of acute respiratory distress syndrome (ARDS). MP (1 mg/kg) was given as a loading infusion over 30 minutes followed by a 1 mg/kg/day continuous i.v. infusion. Patients were switched to oral MP upon restoration of oral intake. MP plasma concentrations (n = 110) were determined using a specific HPLC method. Population pharmacokinetic analysis was performed using nonlinear mixed-effects models, implemented in NONMEM, version V. MP plasma concentration data were described by a one-compartment open model with a time-dependent, non-linear increase in the clearance (CL) of MP during the course of therapy. Initial clearance of MP (CLo) in ARDS patients at the start of therapy increased to a maximal value (CLmax) after approximately 7 days. The estimate of CLmax was similar to the CL of MP in healthy individuals reported previously. Population mean estimates (+/- SE) of parameters in the model were as follows: CLo = 13.2 +/- 2.4 L/h, CLmax = 25.0 +/- 3.6 L/h, time of half-maximal increase in CL (T50) = 41.1 +/- 8.2 h, gamma (Hill coefficient) = 3.8 +/- 0.6, and volume of distribution (Vd) = 137 +/- 30.2 L. Disease progression indices and patient demographics were evaluated as covariates, and no significant correlation was found. Means (+/- SD) of plasma protein binding differed between healthy individuals (72% +/- 4%) and ARDS patients (46% +/- 11%) (p < 0.001). The pharmacokinetics of MP in ARDS patients has not been described previously.

IgG-mediated anaphylaxis via Fc gamma receptor in CD40-deficient mice

Anaphylaxis denotes an immediate hypersensitivity reaction to allergen, exclusively mediated by IgE antibodies. However, IgE antibodies do not explain all the syndromes that are encountered. We investigated potent IgG-mediated anaphylaxis in CD40-deficient mice that lack the immunoglobulin class switching for T cell-dependent antigens. Immunization with ovalbumin did not induce either humoral responses of IgG, IgA, and IgE, or systemic anaphylaxis in CD40-deficient mice. Although systemic anaphylaxis by active immunization was not observed in CD40-deficient mice, both passive cutaneous anaphylaxis (PCA) and passive systemic anaphylaxis assessed by mouse blood pressure monitoring with cervical artery catheterization did take place when antigen-specific IgG was transferred and then antigen challenge given. Further, to investigate the inflammatory pathway of IgG-mediated immediate hypersensitivity reactions, we focused on the Fc gamma receptor (Fc gammaR) function. Pretreatment of the mice with the anti-Fc gammaRII/Fc gammaRIII MoAb clearly blocked the response of PCA and passive systemic anaphylaxis, suggesting that they were initiated through Fc gammaR. In conclusion, we directly demonstrate the IgG-mediated anaphylaxis and its triggering mechanism through Fc gammaR in in vivo conditions. In addition to IgE-mediated anaphylaxis, IgG-mediated anaphylaxis should be considered and the blocking of Fc gammaR would provide one of the therapeutic targets for the control of IgG-mediated hypersensitivity diseases.

Time-dependent effects of Klebsiella pneumoniae endotoxin on hepatic drug-metabolizing enzyme activity in rats

The time-dependent effects of Klebsiella pneumoniae endotoxin on hepatic cytochrome P450-dependent drug-metabolizing capacity (cytochrome P450 and b5 content, activity of aminopyrine N-demethylase, p-nitroanisole O-demethylase, aniline hydroxylase and benzphetamine N-demethylase) and on the pharmacokinetics of antipyrine have been determined in rats. Measurement of enzyme activity and antipyrine (after intravenous injection of 20 mg kg(-1)) were performed 2, 24 and 96 h after a single intraperitoneal injection of endotoxin (1 mg kg(-1)) and after repeated doses (once daily for 4 days). The contribution of tumour necrosis factor alpha (TNFalpha) to the endotoxin-induced changes was also examined in rats pretreated with granulocyte colony-stimulating factor (G-CSF). The systemic clearance of antipyrine and the activity of hepatic cytochrome P450-dependent drug-metabolizing enzymes were dramatically reduced 24 h after a single injection of endotoxin, but had returned to control levels by 96h. The magnitudes of these decreases in these measurements after repeated doses of endotoxin were similar to those seen 24h after the single dose. The systemic clearance of antipyrine correlated significantly with cytochrome P450 content and aminopyrine N-demethylase activity. In histopathological experiments, moderate hypertrophy of Kupffer cells was observed, with no evidence of severe liver-tissue damage. G-CSF pretreatment suppressed the increased plasma concentrations of TNFalpha produced 2 h after single endotoxin injection, but did not eliminate the endotoxin-induced decrease in the systemic clearance of antipyrine, suggesting that TNFalpha is not the sole component responsible for the reduction of cytochrome P450-mediated drug-metabolizing enzyme activity. These results provide evidence that a single intraperitoneal injection of 1.0 mgkg(-1)K. pneumoniae endotoxin in rats reduces hepatic P450 and b5 levels, and reduces the activity of various cytochrome P450-mediated drug-metabolizing enzymes without causing severe liver-tissue damage. This suggests that the effect of endotoxin on hepatic cytochrome P450-mediated drug-metabolizing isozymes is non-selective.

Clinical application of the Biotrack 516 system for determination of theophylline by a turbidimetric latex agglutination inhibition reaction

Several automated analytical systems for therapeutic drug monitoring (TDM) have been developed. In the present study, theophylline concentration in plasma was measured by the Biotrack 516 system for theophylline, a newly developed automated system based on the turbidimetric latex agglutination inhibition reaction, using whole blood samples obtained from 35 asthmatic patients receiving chronic theophylline therapy. The data were compared with those obtained by high-performance liquid chromatography (HPLC) and fluorescence polarization immunoassay (FPIA). Within-day and between-day precisions for the Biotrack system using blood samples obtained from nine patients ranged from 4.1 to 5.8% and from 2.0 to 6.2%, respectively. Comparison of this system with HPLC and FPIA methods indicated good correlation coefficients of > 0.960, while the respective slope and intercept did not differ from unity and zero. No cross-reactivity of this system with the main metabolites of theophylline and caffeine was observed, thus indicating that the antibodies possess specificity for theophylline. These findings suggest that the Biotrack-516 system is a method that enjoys both accuracy and precision to the same degree as established methods and hence will prove useful in the routine monitoring of plasma theophylline concentrations.

Effect of a bacterial lipopolysaccharide on biliary excretion of a beta-lactam antibiotic, cefoperazone, in rats

Klebsiella pneumoniae O3 lipopolysaccharide (LPS) has been found to dramatically modify the pharmacokinetics of the beta-lactam antibiotic cefazolin in rats. This study investigated the effect of LPS on the biliary excretion of the beta-lactam antibiotic cefoperazone (CPZ) in rats. CPZ is known to be actively secreted into the bile by a carrier-mediated transport system. LPS (250 micrograms/kg of body weight) was infused for 20 to 30 min 2 h before an intravenous administration of CPZ (20 mg/kg). The pharmacokinetic parameters of CPZ were estimated by a noncompartment model. LPS induced a significant decrease in the systemic clearance (by approximately 50%) and an increase in the mean residence time of CPZ. Significant decreases were also seen in the bile flow rate and in the biliary recovery of unchanged CPZ in the LPS-treated rats. LPS tended to increase the proportion of urinary excretion of CPZ. LPS significantly decreased the biliary clearance (by approximately 55%) and renal clearance (by approximately 35%) of CPZ. However, no changes in the volume of distribution at steady state for CPZ were observed between the treatment groups. Our findings suggest that LPS induces changes in the pharmacokinetics of CPZ as a result of changes occurring in the biliary secretory system.

Metabolism of caffeine and theophylline in rats with malaria and endotoxin-induced fever

1. The effects of malaria infection due to Plasmodium berghei and Escherichia coli endotoxin-induced fever on the metabolism of orally-administered caffeine (CA: 10 mg/kg) to its primary metabolites (theobromine (TB), paraxanthine (PX) and theophylline (TH)) were studied in 5-week-old male Wistar rats (n = 5 for each treatment). In separate experiments, the effects of malaria and endotoxin-induced fever on the clearance of i.v.-administered theophylline (TH; 15 mg/kg) were studied in another group of rats. 2. The ratios of CA to the three primary metabolites (TB/CA, PX/CA, PH/CA) determined in a single plasma sample obtained 3 h after CA administration were significantly reduced (p < 0.05) both by malaria and fever compared with control (saline) treatment. The clearance of TH determined from the concentration of TH in a single plasma sample obtained 6 h after TH administration was significantly reduced (p < 0.05) by fever but not malaria (4.0 +/- 0.7 ml/min/kg in controls; 4.2 +/- 0.5 in malaria; 2.4 +/- 0.4 in fever). 3. These results suggest that malaria and fever have different effects on CA and TH metabolism in vivo, probably as a result of different effects on the hepatic isozymes involved.

Influence of a bacterial lipopolysaccharide on the pharmacokinetics of tobramycin in rats

The effects of Klebsiella pneumoniae O3 lipopolysaccharide on the renal handling and distribution characteristics of the aminoglycoside tobramycin were investigated in rats. Tobramycin (2 mg kg-1) and inulin (100 mg kg-1) were administered intravenously 2 h after administration of 50, 250 or 500 micrograms kg-1 lipopolysaccharide. Lipopolysaccharide delayed the disappearance of tobramycin from plasma in a dose-dependent manner. A dose-dependent decrease in systemic clearance of tobramycin was observed, although the elimination rate constant and fraction of urinary recovery of unchanged drug were not significantly different in any group. Lipopolysaccharide significantly decreased the central compartment volume of distribution of tobramycin, but did not influence the steady-state volume of distribution. A dose-related increase in the ratio of the rate constant of transfer to the peripheral compartment to the rate constant of transfer from peripheral compartment to central compartment was observed. The glomerular filtration rate was significantly decreased by pretreatment with 250 micrograms kg-1 lipopolysaccharide and the clearance ratio was decreased by 20%, indicating that lipopolysaccharide increases the tubular reabsorption of tobramycin. Our findings suggest that K. pneumoniae O3 lipopolysaccharide modifies the glomerular filtration rate and tubular reabsorption without change in the terminal half-life and that drug distribution characteristics from the rapidly-distributing compartment to the peripheral compartment were altered without expansion of the extracellular fluid volume.

Alterations in pharmacokinetics and protein binding behavior of cefazolin in endotoxemic rats

The possible alterations in the pharmacokinetics and protein binding behavior of the beta-lactam antibiotic cefazolin (CEZ) were investigated in endotoxemic rats induced by Klebsiella pneumoniae O3 lipopolysaccharide (LPS). LPS (250 micrograms/kg of body weight) was infused for 20 to 30 min 2 h before an intravenous administration of CEZ (20 mg/kg). Significant decreases in systemic clearance and renal clearance of CEZ were observed in LPS-treated rats without any changes in fraction of urinary excretion in unchanged CEZ (> 0.8). The volume of distribution at steady state showed a tendency to increase. The protein binding parameters of CEZ, the binding capacity, and number of binding sites on the albumin molecule were decreased by LPS, whereas the dissociation constant did not change. Significant decreases in systemic and renal clearances for unbound CEZ were observed in LPS-treated rats. The glomerular filtration rate estimated as inulin clearance was also decreased by LPS. The ratio of renal clearance of unbound CEZ to glomerular filtration rate (clearance ratio) dropped to 70% of that in control rats, and the net tubular secretion of CEZ was also dramatically reduced. The present study suggests that LPS has an effect on the pharmacokinetics of CEZ by changes which occur in renal handling and protein binding.