Determination of urinary levels of leukotriene B(4) using ad highly specific and sensitive methodology based on automatic MEPS combined with UHPLC-PDA analysis.

Leukotriene B4 (LTB4) is a potent mediator of inflammation and plays a key function in the pathophysiology of chronic asthma. Detectable urinary levels of LTB4, arises from the activation of leukotriene pathways. In this study an ultra-fast, selective and sensitive analytical method based on semi-automatic microextraction by packed sorbents (MEPS) technique, using a new digitally controlled syringe (eVol®) combined with ultra-high pressure liquid chromatography (UHPLC), is proposed for the measurement of urinary LTB4 (U-LTB4) levels in a group of asthmatic patients (APs) and healthy controls (CTRL). Important parameters affecting MEPS performance, namely sorbent type, number of extraction cycles (extract-discard) and elution volume, were evaluated. The optimal experimental conditions among those investigated for the quantification of U-LTB4 in urine samples were as follows: porous graphitic carbon sorbent (PGC), 10 extractions cycle (10×250 µL of sample) and LTB4 elution with 100 µL of acetonitrile. The UHPLC optimum conditions resulted in a mobile phase consisting of 95% (v/v) of acid aqueous solution (v/v), and acetonitrile 5% (v/v); flow rate of 500 µL/min, and a column temperature of 37±0.1 °C. Under optimized conditions the proposed method exhibit good selectivity and sensitivity LOD (0.37 ng/mL) and LOQ (1.22 ng/mL). The recovery ranging from 86.4 to 101.1% for LTB4, with relative standard deviations (% RSD) no larger than 5%. In addition, the method also afforded good results in terms of linearity (r(2)>0.995) within the established concentration range, with a residual deviation for each calibration point below 6%, and intra- and inter-day repeatability in urine samples with RSD values lower than 4 and 5%, respectively. The application of the method to urine samples revealed a tendency towards the increased urinary LTB4 levels in APs (5.42±0.17 ng/mL) when compared to those of CTRL group (from ND to 1.9 ng/mL). Urinary measurement of LTB4 may be an interesting and non-invasive option to assess control of asthma.

The 5-lipoxygenase-activating protein inhibitor, GSK2190915, attenuates the early and late responses to inhaled allergen in mild asthma.

BACKGROUND: GSK2190915, a potent 5-lipoxygenase-activating protein inhibitor, prevents the synthesis of leukotrienes and 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE). OBJECTIVE: To assess the effect of GSK2190915 on the allergen-induced asthmatic responses. METHODS: Nineteen eligible male subjects with mild asthma were enrolled in and completed this four-centre, double-blind, two-way crossover study (ClinicalTrials.gov NCT00748306). Subjects took GSK2190915 100 mg and placebo orally once daily for 5 days in randomized order. On Day 1 and 4 they had a methacholine challenge, on Day 3 they had an inhaled allergen challenge, and on Days 4 and 6 they had sputum induction. RESULTS: GSK2190915 attenuated the early (0-2 h) and late (4-10 h) asthmatic responses to inhaled allergen compared with placebo. There was a statistically significant attenuation of the early asthmatic response (EAR) by GSK2190915; treatment difference of GSK2190915 vs. placebo for the minimum FEV(1) EAR was 0.408 L (0.205, 0.611). There was a statistically significant attenuation of the late asthmatic response (LAR) by GSK2190915; the treatment difference of GSK2190915 vs. placebo for the minimum FEV(1) LAR was 0.229 L (0.041, 0.417). There was a statistically significant attenuation of allergen-induced sputum eosinophil count on Day 4 following GSK2190915: mean treatment difference (95% CI) between GSK2190915 and placebo was -9.95% (-18.15%, -1.77%). Compared with placebo, GSK2190915 100 mg reduced median sputum LTB(4) by > 90% on Days 4 and 6. There was no effect on methacholine PC(20) post allergen. GSK2190915 was generally well tolerated. CONCLUSION AND CLINICAL RELEVANCE: GSK2190915 shows potential as a treatment for patients with asthma.

Lipoxygenase products in the urine correlate with renal function and body temperature but not with acute transplant rejection.

Acute transplant rejection is the leading cause of graft loss in the first months after kidney transplantation. Lipoxygenase products mediate pro- and anti-inflammatory actions and thus we aimed to correlate the histological reports of renal transplant biopsies with urinary lipoxygenase products concentrations to evaluate their role as a diagnostic marker. This study included a total of 34 kidney transplant recipients: 17 with an acute transplant rejection and 17 controls. LTE4, LTB4, 12-HETE and 15-HETE concentrations were measured by enzyme immunoassay. Urinary lipoxygenase product concentrations were not significantly changed during an acute allograft rejection. Nevertheless, LTB4 concentrations correlated significantly with the body temperature (P ≤ 0.05) 3 months after transplantation, and 12- and 15-HETE concentrations correlated significantly with renal function (P ≤ 0.05) 2 weeks after transplantation. In conclusion, our data show a correlation for LTB4 with the body temperature 3 months after transplantation and urinary 12- and 15-HETE concentrations correlate positively with elevated serum creatinine concentrations but do not predict acute allograft rejection.

Pharmacodynamics, pharmacokinetics and safety of GSK2190915, a novel oral anti-inflammatory 5-lipoxygenase-activating protein inhibitor.

AIM: To assess the pharmacokinetics, pharmacodynamics, safety and tolerability of the 5-lipoxygenase-activating protein inhibitor, GSK2190915, after oral dosing in two independent phase I studies, one in Western European and one in Japanese subjects, utilizing different formulations. METHOD: Western European subjects received single (50-1000 mg) or multiple (10-450 mg) oral doses of GSK2190915 or placebo in a dose-escalating manner. Japanese subjects received three of four GSK2190915 doses (10-200 mg) plus placebo once in a four period crossover design. Blood samples were collected for GSK2190915 concentrations and blood and urine were collected to measure leukotriene B4 and leukotriene E4, respectively, as pharmacodynamic markers of drug activity. RESULTS: There was no clear difference in adverse events between placebo and active drug-treated subjects in either study. Maximum plasma concentrations of GSK2190915 and area under the curve increased in a dose-related manner and mean half-life values ranged from 16-34 h. Dose-dependent inhibition of blood leukotriene B4 production was observed and near complete inhibition of urinary leukotriene E4 excretion was shown at all doses except the lowest dose. The EC50 values for inhibition of LTB4 were 85 nM and 89 nM in the Western European and Japanese studies, respectively. CONCLUSION: GSK2190915 is well-tolerated with pharmacokinetics and pharmacodynamics in Western European and Japanese subjects that support once daily dosing for 24 h inhibition of leukotrienes. Doses of ≥50 mg show near complete inhibition of urinary leukotriene E4 at 24 h post-dose, whereas doses of ≥150 mg are required for 24 h inhibition of blood LTB4.

Leukotrienes B4, C4, D4 and E4 in the exhaled breath condensate (EBC), blood and urine in patients with pneumoconiosis.

Leukotrienes (LTs) are involved in the pathogenesis of lung fibrosis and were increased in exhaled breath condensate (EBC) of the patients with pneumoconiosis. However the possible influence of extra-pulmonary disorders on the EBC markers is not known. Therefore in parallel with EBC, LTs' levels in the plasma and urine were measured in patients with pneumoconiosis (45 × asbestos exposure, 37 × silica exposure) and in 27 controls. Individual LTs B4, C4, D4 and E4 were measured by liquid chromatography - electrospray ionization - tandem mass spectrometry (LC-ESI-MS/MS). In EBC, LT D4 and LT E4 were increased in both groups of patients (p<0.001 and p<0.05), comparing with the controls. Both LT B4 and cysteinyl LTs were elevated in asbestos-exposed subjects (p<0.05). Asbestosis with more severe radiological signs (s1/s2-t3/u2) and lung functions impairment has shown higher cysteinyl LTs and LT C4 in the EBC (p<0.05) than mild asbestosis (s1/s0-s1/s1). In addition, in the subjects with asbestosis, cysteinyl LTs in EBC correlated with TLC (-0.313, p<0.05) and TLCO/Hb (-0.307, p<0.05), and LT C4 with TLC (-0.358, p<0.05). In pneumoconioses, EBC appears the most useful from the 3 fluids studied.

The measurement of leukotrienes in urine as diagnostic option in systemic mastocytosis.

Clinical symptoms of patients with mastocytosis may include skin reactions, but also gastrointestinal symptoms with hyperacidity and dysmotility (e.g. ulcer, diarrhea, pain). They are mostly caused by mediators derived from activated mast cells. In order to investigate the impact of leukotrienes on the clinical symptoms excretion of leukotriene B4 (LTB4) and leukotrienes C4-D4-E4 (cysteinyl-leukotrienes) into urine was studied in 9 patients with indolent systemic mastocytosis divided into a group with high and low intensity of symptoms and in 11 healthy volunteers. Leukotriene excretion was determined by ELISA and correlated with methylhistamine excretion. Patients with systemic mastocytosis with high and low intense symptoms showed significantly higher urinary excretion of cysteinyl-leukotrienes than controls. There was a positive correlation of cysteinyl-leukotriene excretion and urinary methylhistamine excretion. LTB4 excretion was also significantly increased in patients with systemic mastocytosis compared to healthy volunteers. No correlation of urinary LTB4 excretion with urinary methylhistamine was observed. The present study demonstrates that urinary excretion of LTB4 and cysteinyl-leukotrienes LTC4-D4-E4 is clearly enhanced in indolent systemic mastocytosis Hence, determination of leukotriene excretion into urine can be used as a tool in the diagnostic and in the therapeutic monitoring of systemic mastocytosis.

Changes in cysteinyl leukotrienes during and after cardiac surgery with cardiopulmonary bypass in patients with and without chronic obstructive pulmonary disease.

OBJECTIVE: Pulmonary function frequently deteriorates after cardiopulmonary bypass (CPB). Chronic obstructive pulmonary disease (COPD) increases risk of respiratory complications after CPB. Cysteinyl leukotrienes are important mediators of respiratory dysfunction. Their role during cardiac surgery and its lung complications is incompletely understood. We studied whether production of cysteinyl leukotrienes changes during and after cardiac surgery with CPB and differs between patients with and without COPD. METHODS: Patients with (n = 9) and without (n = 10) moderate-to-severe COPD undergoing cardiac surgery with CPB were prospectively included. Plasma and urinary cysteinyl leukotriene and leukotriene B(4) concentrations were measured by enzyme-linked immunosorbent assay after anesthesia induction, at end of CPB, after CPB, and 2 hours after intensive care unit admission. Gas exchange and respiratory mechanics were also assessed. RESULTS: Patients with COPD had larger airway resistances after CPB and chest closure (P < .001), lower ratio of arterial Po(2) to inspired oxygen fraction at intensive care unit admission (215 ± 37 vs 328 ± 30 mm Hg, P < .05), and longer postoperative mechanical ventilation (13.7 ± 5.8 vs 6.8 ± 3.4 hours, P < .01). Urinary cysteinyl leukotriene concentrations increased with time in both groups (P < .01), but more in patients with than without COPD (P < .05). Plasma cysteinyl leukotriene concentrations increased significantly between baseline and intensive care unit admission in patients with but not without COPD (P < .01). Concentrations of leukotriene B(4) in plasma and urine did not increase significantly with time and were not different between groups. CONCLUSIONS: Release of cysteinyl leukotrienes increases during cardiac surgery with CPB and is larger in patients with than without COPD. This may be related to higher lung and airway production of cysteinyl leukotrienes and neutrophil activation in patients with COPD.

Role of leukotriene B4 in accelerated hyperlipidaemic renal injury.

AIM: Glomerular infiltration of macrophages is a characteristic alteration of renal pathology in hyperlipidaemic renal injury. Leukotriene B4 (LTB4) is a bioactive eicosanoid and macrophage and has two key enzymes for LTB4 synthesis, 5-lipoxygenase and leukotriene A4 (LTA4) hydrolase. The purpose of this study was to evaluate the role of LTB4 in accelerated hyperlipidaemic renal injury. METHODS: To induce accelerated hyperlipidaemic renal injury, 8 week old male spontaneously hypercholesterolaemic (SHC) rats were fed with a high cholesterol diet for 6 weeks. LTA4 hydrolase activities in the kidney and urine LTB4 levels were examined. The effects of LTB4 antagonist (ONO-4057) were also evaluated. RESULTS: Urinary protein and LTB4 excretion was increased by a high cholesterol diet for 6 weeks. The scores of glomerular foam cell accumulation and sclerosis, numbers of infiltrated macrophages in glomeruli and interstitial area, LTA4 hydrolase activity in renal cortex were higher in the high cholesterol diet group than the normal diet group. LTB4 antagonist treatment reduced urinary protein and LTA4 activity and attenuated renal pathological changes. CONCLUSION: These results suggest that LTB4 directly contributes to accelerated hyperlipidaemic renal injury and the therapeutic potential of LTB4 antagonist for renal damage induced by hyperlipidaemia.

Inverse temporal changes of lipoxin A4 and leukotrienes in children with Henoch-Schönlein purpura.

The pathogenesis of Henoch-Schönlein purpura (HSP) is not clearly understood. It remains unclear how changes of lipoxin A(4) (LXA(4)) that acts as a "braking signal" in inflammatory process occur in patients with HSP. In this study, we determined the temporal changes of blood and urinary LXA(4), Leukotriene (LT)B(4) and urinary LTE(4) in 49 children with HSP. Inverse temporal changes between gradually increased blood and urinary LXA(4) and gradually decreased blood and urinary LTB(4) and urinary LTE(4) were found in patients with HSP. Furthermore, both 15-S-hydroxyeicosatetraenoic acid and LXA(4) inhibited the LTB(4)-induced chemotaxis of leukocytes and release of LTB(4) from leukocytes obtained from the patients in the active phase of HSP. In 22 children with HSP nephritis, concordant with the gradually increased severity of mesangial proliferation and proteinuria, the glomerular expressions of 15-lipoxygenase and the levels of urinary LXA(4) gradually decreased and the glomerular expressions of LTC(4) synthase and the urinary LTE(4) and LTB(4) gradually increased. The levels of blood and urinary LXA(4) in patients with HSP nephritis were lower than those in patients with purpura alone in early resolution of HSP. The levels of blood and urinary LTB(4) and urinary LTE(4) in the patients with HSP nephritis were higher than those in patients with purpura alone in early resolution of HSP. There was positive correlation between blood LTB(4) and serum C-reactive protein in 49 children with HSP. These data suggest that LTs may play a proinflammatory and profibrotic role in the pathogenesis of HSP, and insufficiency of LXA(4) may be responsible for the patients with HSP whose illness become more serious.

A novel polymorphism, E254K, in the 5-lipoxygenase gene associated with bronchial asthma.

Cysteinyl-leukotrienes are important pro-inflammatory mediators in bronchial asthma (BA) and are derived from arachidonic acid by the action of 5-lipoxygenase. We identified a novel polymorphism, c.760 G>A (E254K), in exon 6 of the 5-lipoxygenase gene (5-LO). This substitution was detected in 11 out of 180 patients with BA, but not in any of the 150 non-allergic subjects. The frequency of c.760 G>A showed a significant difference between BA and non-allergic subjects (P=0.0007). The c.760 G>A polymorphism existed at the surface edge of the C-terminal catalytic domain, and the E-to-K substitution changed the charge of the side chain from negative to positive. Thus, our results suggest that E254K in the 5-LO might be associated with BA.

Quantification of leukotriene B4 glucuronide in human urine.

We have developed a method for measuring leukotriene B4 glucuronide, a marker of systemic leukotriene B4 biosynthesis, in human urine. This method involves the separation of two positional isomers of leukotriene B4 glucuronide by high-performance liquid chromatography, followed by hydrolysis with beta-glucuronidase and then leukotriene B4 quantification by enzyme immunoassay after purification by high-performance liquid chromatography. One of two positional isomers of leukotriene B4 glucuronide was predominantly present in urine. The concentration of the isomer increased in urine from aspirin-intolerant asthma patients after aspirin challenge. Urinary leukotriene E4 and leukotriene B4 glucuronide concentrations in 13 normal healthy adults were 94.6 pg/mg-creatinine (median) and 22.3 pg/mg-creatinine, respectively. Urinary LTE4 concentration increased during the first 3h after allergen inhalation in atopic patients. However, allergen-induced bronchoconstriction was not associated with an increased concentration of LTB4 glucuronide in urine. The method enabled us to precisely determine urinary leukotriene B4 glucuronide concentration.

Urine leukotriene B4 in familial Mediterranean fever and other forms of right lower abdominal pain.

BACKGROUND: Acute right lower abdominal pain may present a diagnostic dilemma. Leukotrienes have been found to be elevated in familial Mediterranean fever (FMF), a disease manifesting with recurrent episodes of "acute abdomen." OBJECTIVES: To determine whether urine leukotriene B4 (LTB4) may differentiate between an FMF attack and some other forms of acute right lower abdominal pain. METHODS: The LTB4 level was determined, using a commercial enzyme-linked immunosorbent assay (ELISA), in urine samples obtained from 36 patients with acute (< 24 hours) right lower abdominal pain presenting to the emergency department, and from 18 healthy volunteers. RESULTS: Compared with the healthy control subjects, LTB4 was significantly higher in those who had FMF (12 patients, p < 0.03). In other forms of acute right lower abdominal pain, including appendicitis (eight patients), urologic disorders (eight patients), and nonspecific abdominal pain (eight patients), intermediate levels of LTB4 were observed, not significantly different from those of either FMF patients or healthy control subjects. CONCLUSIONS: In the samples tested, urine LTB4 levels were not instrumental in differentiating FMF from other acute right lower abdominal pain.

Urine leukotriene B4 in familial Mediterranean fever.

OBJECTIVE: To determine urinary leukotriene B4 (LTB4) levels and their role in FMF: METHODS: Urinary LTB4 levels were studied using a commercial ELISA kit in 12 FMF patients during abdominal attacks, and 20 FMF patients during remission. RESULTS: Urinary LTB4 levels in FMF patients during attacks were comparable to those during remission, but higher than normal levels (p = 0.03). CONCLUSIONS: These findings suggest a persistent activation of the leukotriene pathway in FMF. Whether elevated LTB4 levels are the cause or the effect of inflammation is yet to be determined.

Increase in urinary leukotriene B4 glucuronide concentration in patients with aspirin-intolerant asthma after intravenous aspirin challenge.

BACKGROUND: Aspirin challenge of aspirin-intolerant asthma (AIA) patients causes a significant increase in leukotriene E4 (LTE4) concentration in urine. However, knowledge on leukotriene B4 (LTB4) generation in patients with AIA is insufficient. Recent research has demonstrated that exogenously administered LTB4 is excreted as glucuronide into the urine in human healthy subjects. OBJECTIVE: The purpose of this study is to estimate urinary LTB4 glucuronide (LTBG) concentration in the clinically stable condition in healthy subjects and asthmatic patients and to investigate changes in urinary LTBG concentration in patients with AIA after aspirin challenge. METHODS: A provocation test was performed by intravenous aspirin challenge. After urine was hydrolysed by beta-glucuronidase, the fraction containing LTB4 was purified by high-performance liquid chromatography and LTB4 concentration was quantified by enzyme immunoassay. Urinary LTBG concentration was calculated as the difference between the concentration obtained with hydrolysis and that without hydrolysis. RESULTS: (1) After hydrolysis, the presence of urinary LTB4 was verified by gas chromatography-mass spectrometry-selected ion monitoring. (2) The urinary LTBG concentration was significantly higher in the asthmatic patients than in the healthy subjects (median, 5.37 pg/mg creatinine [range 1.2-13] vs. 3.32 pg/mg creatinine [range, 0.14-10.5], P = 0.0159). (3) The patients with AIA (n = 7), but not those with aspirin-tolerant asthma (n = 6), showed significant increases in LTBG and LTE4 excretions after aspirin challenge. (4) When the concentrations after aspirin challenge were analysed simultaneously, a significant linear correlation was observed between urinary LTBG concentration and urinary LTE4 concentration in patients with AIA (Spearman's rank correlation test, r = 0.817, P = 0.0003). CONCLUSION: LTBG is present in human urine, albeit at a concentration lower than urinary LTE4. In addition to a marked increase in cysteinyl-leukotriene production, aspirin challenge induced LTB4 production in AIA patients.

Urinary metabolites of leukotriene B4 in the human subject.

Leukotriene B4 (LTB4) is a potent chemoattractant for neutrophils and is thought to play a role in a variety of inflammatory responses in humans. The metabolism of LTB4 in vitro is complex with several competing pathways of biotransformation, but metabolism in vivo, especially for normal human subjects, is poorly understood. As part of a Phase I Clinical Trial of human tolerance to LTB4, four human subjects were injected with 150 nmol/kg LTB4 with one additional subject as placebo control. The urine of the subjects was collected in two separate pools (0-6 and 7-24 h), and aliquots from these urine collections were analyzed using high performance liquid chromatography, UV spectroscopy, and negative ion electrospray ionization tandem mass spectrometry for metabolites of LTB4. In the current investigation, 11 different metabolites of LTB4 were identified in the urine from those subjects injected with LTB4, and none were present in the urine from the placebo-injected subject. The unconjugated LTB4 metabolites found in urine were structurally characterized as 18-carboxy-LTB4, 10,11-dihydro-18-carboxy-LTB4, 20-carboxy-LTB4, and 10,11-dihydro-20-carboxy-LTB4. Several glucuronide-conjugated metabolites of LTB4 were characterized including 17-, 18-, 19-, and 20-hydroxy-LTB4, 10-hydroxy-4,6,12-octadecatrienoic acid, LTB4, and 10,11-dihydro-LTB4. The amount of LTB4 glucuronide (16.7-29.4 pmol/ml) and 20-carboxy-LTB4 (18.9-30.6 pmol/ml) present in the urine of subjects injected with LTB4 was determined using an isotope dilution mass spectrometric assay before and after treatment of the urine samples with beta-glucuronidase. The urinary metabolites of LTB4 identified in this investigation were excreted in low amounts, yet it is possible that one or more of these metabolites could be used to assess LTB4 biosynthesis following activation of the 5-lipoxygenase pathway in vivo.

Eicosanoids in sickle cell disease: potential relevance of neutrophil leukotriene B4 to disease pathophysiology.

Neutrophil activation with the release of intracellular granule contents has been observed in sickle cell disease (SCD). Because leukotriene B(4) (LTB(4)), a 5-lipoxygenase metabolite of arachidonic acid in neutrophils, is a chemoattractant and enhances neutrophil adhesion to endothelium, we assessed plasma levels of this metabolite in controls (n = 9) and individuals with SCD, SS genotype, both in basal "steady state" (n = 37) and during episodes of vaso-occlusion (n = 10) and acute chest syndrome (n = 5). Thirteen patients with SCD, SC genotype, in steady state were also studied. Although no significant differences were noted between the control (136 +/- 32 fmol/mL) and SC genotype (177 +/- 83 fmol/mL, P >.15), LTB(4) levels were markedly increased in patients with SS genotype in basal steady state (207 +/- 64 fmol/mL, P <.003) compared with those in controls. Values were further increased during vaso-occlusion (264 +/- 94 fmol/mL) and acute chest syndrome (363 +/- 124 fmol/mL). These levels were significantly different from measurements taken during steady state (P <.04 and P <.0001, respectively). No correlation was noted between LTB(4) level and total white cell or neutrophil count. Additionally, the significant correlation noted in SCD between increased levels of plasma LTB(4) and soluble L-selectin (P <.03) reflects neutrophil activation. We also observed an effect of LTB(4) on red cell-endothelial adhesion at concentrations that appear clinically relevant (1-10 pmol/mL) with concomitant up-regulation of mRNA for the endothelial vitronectin receptor. These properties of LTB(4) are relevant to disease pathophysiology, providing further evidence of the contribution of the neutrophil to the proinflammatory and proadhesive phenotype in SCD.

Clinical, biochemical and molecular genetic characteristics of 19 patients with the Sjögren-Larsson syndrome.

Sjögren-Larsson syndrome (SLS) is an autosomal recessively inherited neurocutaneous disorder caused by a deficiency of the microsomal enzyme fatty aldehyde dehydrogenase (FALDH). We report the clinical characteristics and the results of molecular studies in 19 SLS patients. Patients 1-17 show the classical triad of severe clinical abnormalities including ichthyosis, mental retardation and spasticity. Most patients were born preterm, and all patients exhibit ocular abnormalities and pruritus. Electro-encephalography shows a slow background activity, without other abnormalities. MRI of the brain shows an arrest of myelination, periventricular signal abnormalities of white matter and mild ventricular enlargement. Cerebral (1)H-MR spectroscopy reveals a characteristic, abnormal lipid peak. The degree of white matter abnormality in the MRIs and the height of the lipid peak in (1)H-MR spectra do not correlate with the severity of the neurological signs. The clinical presentation and the clinical course is strikingly similar in these patients. Patient 18 shows a mild phenotype that essentially contains the same, but less severe, clinical features. Patient 19 exhibits the typical, but very mild, dermatological and ocular abnormalities, without any clinical neurological involvement. The diagnosis of SLS was confirmed by demonstration of the enzyme defect in cultured skin fibroblasts. Furthermore, as might be predicted from the essential role of FALDH in leucotriene B(4) (LTB(4)) metabolism, elevated urinary concentrations of LTB(4) and 20-OH-LTB(4) were found in all patients studied. Molecular studies of the FALDH gene revealed eight different mutations, including three new ones: a large 26-base pair deletion (21-46del), a missense mutation (80C-->T) and an insertion mutation (487-488insA). The vast majority of SLS patients seem to be severely affected independent of their genotype.

Enhanced urinary excretion of cysteinyl leukotrienes in patients with acute alcohol intoxication.

BACKGROUND & AIMS: Leukotrienes are proinflammatory mediators. Ethanol inhibits the catabolism of both cysteinyl leukotrienes (leukotriene E(4) [LTE(4)] and N-acetyl-LTE(4)) and leukotriene B(4) (LTB(4)) in hepatocytes. We examined the metabolic derangement of leukotriene inactivation by ethanol in humans in vivo. METHODS: LTE(4), N-acetyl-LTE(4), LTB(4), and 20-hydroxy-LTB(4) were quantified in urine samples from 16 patients with acute alcohol intoxication (mean blood ethanol, 75 mmol/L). In 9 healthy volunteers, urinary LTE(4) was determined before and after ethanol consumption (mean blood ethanol, 14 mmol/L). RESULTS: The excretion of LTE(4) during alcohol intoxication was 286 compared with 36 nmol/mol creatinine in healthy subjects (P < 0.01); the corresponding values for N-acetyl-LTE(4) were 101 and 11 nmol/mol creatinine, respectively (P < 0.001). This excretion of cysteinyl leukotrienes decreased when the blood ethanol concentration returned to normal. LTB(4) and 20-hydroxy-LTB(4) were detectable only in patients with excessive blood ethanol concentrations (mean, 95 mmol/L). In healthy volunteers, LTE(4) excretion increased 3-5 hours after ethanol consumption (mean peak concentration of 1.5 nmol/L compared with 0.5 nmol/L for basal values; P < 0.005). CONCLUSIONS: Ethanol at high concentration induces increased leukotriene excretion into urine. These changes are consistent with inhibition of leukotriene catabolism and inactivation induced by ethanol, as well as with a higher leukotriene formation caused by ethanol-induced endotoxemia.

5-Lipoxygenase inhibition: a new treatment strategy for Sjögren-Larsson syndrome.

The Sjögren-Larsson syndrome (SLS) is a severe neurocutaneous disorder due to fatty aldehyde dehydrogenase (FALDH) deficiency. The recent discovery of the role of FALDH in the degradation of leukotriene B4 (LTB4) opened the way to the development of a new therapeutic strategy for SLS, i.e. 5-lipoxygenase inhibition. We treated one SLS patient with zileuton during five weeks. During the treatment period we found decreased values of LTB4 and omega-OH-LTB4. The severity of the pruritus diminished, and favorable changes in the child's behavior were observed. The height of the prominent "lipid peak" of cerebral white matter (that is characteristically found on proton magnetic resonance spectroscopy in SLS patients) decreased during treatment, and increased again when treatment was stopped. In conclusion, the beneficial effects of 5-lipoxygenase inhibition in SLS are very promising and encourage further research.