5-Lipoxygenase Inhibition Protects Retinal Pigment Epithelium from Sodium Iodate-Induced Ferroptosis and Prevents Retinal Degeneration.

Excessive reactive oxygen species (ROS) contribute to damage of retinal cells and the development of retinal diseases including age-related macular degeneration (AMD). ROS result in increased metabolites of lipoxygenases (LOXs), which react with ROS to induce lipid peroxidation and may lead to ferroptosis. In this study, the effect of 5-LOX inhibition on alleviating ROS-induced cell death was evaluated using sodium iodate (NaIO3) in the retinal pigment epithelium (RPE) cell line ARPE-19 and a mouse model investigating oxidative stress in AMD. We demonstrated that NaIO3 induced cell death in the RPE cells through mechanisms including ferroptosis. Inhibition of 5-LOX with specific inhibitor, Zileuton, or siRNA knockdown of ALXO5 mitigated NaIO3-induced lipid peroxidation, mitochondrial damage, DNA impairment, and cell death in ARPE-19 cells. Additionally, in the mouse model, pretreatment with Zileuton reduced the NaIO3-induced lipid peroxidation of RPE cells, cell death in the photoreceptor layer of the retina, inflammatory responses, and degeneration of both the neuroretina and RPE monolayer cells. Our results suggest that 5-LOX plays a crucial role in ROS-induced cell death in the RPE and that regulating 5-LOX activity could be a useful approach to control ROS and ferroptosis-induced damage, which promote degeneration in retinal diseases.

Exploration of Long-Chain Vitamin E Metabolites for the Discovery of a Highly Potent, Orally Effective, and Metabolically Stable 5-LOX Inhibitor that Limits Inflammation.

Endogenous long-chain metabolites of vitamin E (LCMs) mediate immune functions by targeting 5-lipoxygenase (5-LOX) and increasing the systemic concentrations of resolvin E3, a specialized proresolving lipid mediator. SAR studies on semisynthesized analogues highlight α-amplexichromanol (27a), which allosterically inhibits 5-LOX, being considerably more potent than endogenous LCMs in human primary immune cells and blood. Other enzymes within lipid mediator biosynthesis were not substantially inhibited, except for microsomal prostaglandin E2 synthase-1. Compound 27a is metabolized by sulfation and ß-oxidation in human liver-on-chips and exhibits superior metabolic stability in mice over LCMs. Pharmacokinetic studies show distribution of 27a from plasma to the inflamed peritoneal cavity and lung. In parallel, 5-LOX-derived leukotriene levels decrease, and the inflammatory reaction is suppressed in reconstructed human epidermis, murine peritonitis, and experimental asthma in mice. Our study highlights 27a as an orally active, LCM-inspired drug candidate that limits inflammation with superior potency and metabolic stability to the endogenous lead.

5-Lipoxygenase inhibition reduces inflammation and neuronal apoptosis via AKT signaling after subarachnoid hemorrhage in rats.

Early brain injury (EBI) is a major contributor to the high mortality and morbidity after subarachnoid hemorrhage (SAH). Inflammatory responses and neuronal apoptosis are important causes of EBI. Because 5- lipoxygenase (5-LOX) is known to be involved various central nervous system diseases, we investigated the effects of 5-LOX inhibition during EBI after SAH. Zileuton and LY294002 were used to inhibit expression of 5-LOX and Akt, respectively. We found that 5-LOX expression was significantly increased in the cytoplasm of cortical neurons after SAH and was accompanied by upregulated expression of the inflammatory factors LTB4, TNF-α, IL-1ß and IL-6; upregulation of the pro-apoptotic factor Bax; downregulation of the anti-apoptotic factor Bcl-2; and an increased apoptosis rate. Gastric Zileuton administration significantly suppressed all of those effects and improved neurological function. Zileuton also upregulated activated (phosphorylated) AKT levels, and these beneficial effects of Zileuton were abolished by intracerebroventricular infusion of the PI3K inhibitor LY294002. Taken together, these findings indicate that 5-LOX mediates pro-inflammatory and pro-apoptotic effects that contribute to EBI after SAH and that those effects are suppressed by activation of PI3K/Akt signaling. This suggests targeting 5-LOX may be an effective approach to treating EBI after SAH.

Curcumin and LOXblock-1 ameliorate ischemia-reperfusion induced inflammation and acute kidney injury by suppressing the semaphorin-plexin pathway.

AIMS: Ischemia/reperfusion (I/R) is one of the most important causes of acute kidney injury (AKI), a clinical syndrome with kidney dysfunction and high mortality rates. New diagnostic biomarkers need to be defined to better illuminate the pathophysiology of AKI. For the first time, we aim to investigate the protective effects of Curcumin which is known for its antioxidant and anti-inflammatory properties and 12/15 lipoxygenase inhibitor LOXblock-1 on I/R induced AKI by modulating inflammatory processes, oxidative stress, apoptosis and semaphorin-plexin pathway. MAIN METHODS: The rats were divided into five groups, with eight animals per group: Sham, I/R, I/R + DMSO (1%, i.p.), I/R + Curcumin (100 mg/kg, i.p.), I/R + LOXblock-1 (2 µg/kg, i.p.). KEY FINDINGS: The renal function biomarkers (BUN, CREA and UA) in serum were significantly increased in the I/R group. The inflammatory (TNF-α, IL-6 and MCP-1), apoptotic (CYCS and CASP3) and oxidative stress parameters (MDA, MPO, TAS and TOS) measured by ELISA were significantly increased in the I/R group. In histopathological analysis, it was observed that I/R caused serious damage to kidney tissue. SEMA3A was found to increase both serum level and mRNA expression in I/R group. It was observed that curcumin and LOXblock-1 reduce inflammatory processes, oxidative stress and apoptosis via the semaphorin-plexin pathway by both measurements and histopathological analysis. Curcumin was proved more effective than LOXblock-1 with its antioxidant feature in I/R injury. SIGNIFICANCE: The current study reveals the protective effects of Curcumin and LOXblock-1 on acute kidney injury by suppressing SEMA3A as a new biomarker.

Development of a highly sensitive liquid chromatography-mass spectrometry method to quantify plasma leukotriene E4 and demonstrate pharmacological suppression of endogenous 5-LO pathway activity in man.

Low basal endogenous concentrations (<20 pg/mL) of the 5-lipoxygenase (5-LO) pathway biomarker leukotriene E4 (LTE4) in human plasma present a significant analytical challenge. Analytical methods including liquid chromatography-mass spectrometry and enzyme linked immunosorbent assays have been used to quantify plasma LTE4 in the past but have not provided consistent data in the lower pg/mL-range. With our new method, a detection limit (<1 pg/mL plasma) significantly below basal levels of LTE4 was achieved by combining large volume sample purification and enrichment by anion-exchange mixed mode solid phase extraction (SPE) with large volume injection followed by chromatographic separation by ultra performance liquid chromatography (UPLC) and quantification by highly sensitive negative-ion electrospray tandem mass spectrometry (MS/MS). The method was reproducible, accurate and linear between 1 and 120 pg/mL plasma LTE4. The method was used to perform an analysis of plasma samples collected from healthy volunteers in a Phase 1 study with the FLAP (5-lipoxygenase activating protein) inhibitor AZD5718. Basal endogenous LTE4 levels of 5.1 ± 2.7 pg/mL were observed in healthy volunteers (n = 34). In subjects that had been administered a single oral dose of AZD5718, significant suppression (>80%) of plasma LTE4 level was observed, providing pharmacological evidence that endogenous 5-LO pathway activity could be assessed.

Conjugation of 4-aminosalicylate with thiazolinones afforded non-cytotoxic potent in vitro and in vivo anti-inflammatory hybrids.

Eicosanoids like leukotrienes and prostaglandins that produced within the arachidonic acid cascade are involved in the pathogenesis of pain, acute and chronic inflammatory diseases. A promising approach for an effective anti-inflammatory therapy is the development of inhibitors targeting more than one enzyme of this cascade. Aiming to develop balanced COX/LOX inhibitors; 4-aminosalicylate based thiazolinones having different substituents at the 5th position of the 4-thiazolinone ring (2-22) were designed, synthesized, characterized and evaluated in vitro and in vivo for their anti-inflammatory activity. Most of the investigated compounds showed high COX-2 inhibitory potencies (IC50 39-200 nM) with selectivity indexes (30-84). Two compounds, 19 and 21, (IC50 = 41 and 44 nM), are equipotent to celecoxib (IC50 = 49 nM), while compound 22 (IC50 = 39 nM) was the most potent. For 15-LOX, compounds 5, 11, 19, 21 and 22 revealed higher potency (IC50 1.5-2.2 µM) than zileuton (IC50 15 µM). Thus, compounds 5, 11, 19, 21 and 22 are potent dual inhibitors of COX-2 and 15-LOX. In vivo anti-inflammatory testing of these compounds revealed that, compounds 5 and 21 had an anti-inflammatory activity similar to indomethacin and celecoxib (% inhibition of oedema = 60 ±â€¯9) and higher than diclofenac potassium (% inhibition = 52 ±â€¯29), while compound 22 (% inhibition = 63 ±â€¯5) was more active than the reference drugs. The results showed that the activity is controlled by the bulkiness and lipophilicity of the substituent at the 5th position. The cytotoxicity results revealed that all compounds are not cytotoxic, additionally, in an experimental model of ulcerogenic effect, the most active compounds 21 and 22 showed better safety profile than indomethacin. Further, at the active sites of the COX-1, COX-2 and 15-LOX co-crystal, 19, 21, and 22 showed high binding forces in free binding energy study, which is consistent with in vitro and in vivo results. In conclusion, these compounds are good candidates for further biological investigation as potential anti-inflammatory drugs with dual balanced inhibition of COX and 15-LOX and good safety profile.

Zafirlukast in combination with pseudohypericin attenuates spinal cord injury and motor function in experimental mice.

BACKGROUND: Biosynthesis of leukotriene (LT) by arachidonic acid involves 5-lipoxygenase (5-LO) as an important precursor. Here, we evaluated the role of pseudohypericin (PHP) for its postulated 5-LO inhibitory activity along with a Cys-LT receptor antagonist zafirlukast (ZFL) against inflammatory response and tissue injury in mice. MATERIALS AND METHODS: The spinal injury was induced by two-level laminectomy of T6 and T7 vertebrae. The inflammation was assessed by histology, inflammatory mediators by enzyme-linked immunosorbent assay, apoptosis by Annexin-V, FAS staining, terminal deoxynucleoti-dyltransferase-mediated UTP end labeling (TUNEL) assay and expression of Bax and Bcl-2 by Western blot. Effect on motor recovery of hind limbs was evaluated for 10 days postinjury. RESULTS: The spinal injury resulted in tissue damage, apoptosis, edema, infiltration of neutrophils with increased expression of tumor necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2). The spinal tissue showed elevated levels of prostaglandin E2 (PGE2), and LTB4 and increased phosphorylation of injured extracellular signal-regulated kinase-1/2 (ERK1/2). The PHP, ZFL and combination decreased inflammation, tissue injury and infiltration of neutrophils. Treatment also decreased the levels of PGE2, phosphorylation of extracellular signal-regulated kinase-1/2 (pERK 1/2), LT, TNF-α and COX-2 with a marked reduction in apoptosis and improved the motor function. CONCLUSION: The present study confirmed 5-LO antagonist activity of PHP and established its neuroprotective role along with ZFL.

First Selective 12-LOX Inhibitor, ML355, Impairs Thrombus Formation and Vessel Occlusion In Vivo With Minimal Effects on Hemostasis.

OBJECTIVE: Adequate platelet reactivity is required for maintaining hemostasis. However, excessive platelet reactivity can also lead to the formation of occlusive thrombi. Platelet 12(S)-lipoxygenase (12-LOX), an oxygenase highly expressed in the platelet, has been demonstrated to regulate platelet function and thrombosis ex vivo, supporting a key role for 12-LOX in the regulation of in vivo thrombosis. However, the ability to pharmacologically target 12-LOX in vivo has not been established to date. Here, we studied the effect of the first highly selective 12-LOX inhibitor, ML355, on in vivo thrombosis and hemostasis. APPROACH AND RESULTS: ML355 dose-dependently inhibited human platelet aggregation and 12-LOX oxylipin production, as confirmed by mass spectrometry. Interestingly, the antiplatelet effects of ML355 were reversed after exposure to high concentrations of thrombin in vitro. Ex vivo flow chamber assays confirmed that human platelet adhesion and thrombus formation at arterial shear over collagen were attenuated in whole blood treated with ML355 comparable to aspirin. Oral administration of ML355 in mice showed reasonable plasma drug levels by pharmacokinetic assessment. ML355 treatment impaired thrombus growth and vessel occlusion in FeCl3-induced mesenteric and laser-induced cremaster arteriole thrombosis models in mice. Importantly, hemostatic plug formation and bleeding after treatment with ML355 was minimal in mice in response to laser ablation on the saphenous vein or in a cremaster microvasculature laser-induced rupture model. CONCLUSIONS: Our data strongly support 12-LOX as a key determinant of platelet reactivity in vivo, and inhibition of platelet 12-LOX with ML355 may represent a new class of antiplatelet therapy.

Inhibition of 12/15 LOX ameliorates cognitive and cholinergic dysfunction in mouse model of hypobaric hypoxia via. attenuation of oxidative/nitrosative stress.

12/15 Lipoxygenase has recently been described as potent propagator of oxidative stress and is closely associated with cognitive decline in neurodegenerative diseases. The mechanism/s behind 12/15 LOX involvement in cognitive deficits remain obscure. The current study has been designed to investigate the underlying role of 12/15LOX and effect of 12/15 LOX inhibition on hypobaric hypoxia-induced memory impairment and cholinergic deficits. Male Balb/c mice subjected to simulated hypobaric hypoxia/reoxygenation condition for 3days showed marked working memory impairment concomitant with hippocampal neuronal damage and malondialdehyde production which were significantly attenuated by baicalein, a specific inhibitor of 12/15LOX. Hypobaric hypoxia-exposed mice had consistently increased expression of 12/15LOX and elevated 12(S) HETE levels in the hippocampus as well as plasma which were significantly mitigated following baicalein treatment. 12/15LOX inhibition also reduced hypobaric hypoxia-mediated upregulation of hippocampal HIF-1α protein expression along with reduction in expression of inflammatory genes. The inhibition of 12/15 LOX resulted in a significant decrease in NO levels in the hippocampal homogenate associated with downregulated iNOS, nNOS transcription but not eNOS speculating that 12/15 LOX is critically involved in HIF-1α, mediated by nitric oxide-induced neurotoxicity. We also observed a similar effect of 12/15 LOX inhibition on hippocampal COX2 expression. 12/15LOX inhibition could effectively modulate central cholinergic indices during hypobaric hypoxia by restoring mAChR-1, α7NAChR expression and AChE, ChAT activity in the hippocampus comparable to normal mice. We report here the mechanistic involvement of 12/15LOX in orchestrating hypoxia-associated neuronal damage and HIF-1α-dependent neuroinflammation resulting in cognitive decline.

Naja sputatrix Venom Preconditioning Attenuates Neuroinflammation in a Rat Model of Surgical Brain Injury via PLA2/5-LOX/LTB4 Cascade Activation.

Inflammatory preconditioning is a mechanism in which exposure to small doses of inflammatory stimuli prepares the body against future massive insult by activating endogenous protective responses. Phospholipase A2/5-lipoxygenase/leukotriene-B4 (PLA2/5-LOX/LTB4) axis is an important inflammatory signaling pathway. Naja sputatrix (Malayan spitting cobra) venom contains 15% secretory PLA2 of its dry weight. We investigated if Naja sputatrix venom preconditioning (VPC) reduces surgical brain injury (SBI)-induced neuroinflammation via activating PLA2/5-LOX/LTB4 cascade using a partial frontal lobe resection SBI rat model. Naja sputatrix venom sublethal dose was injected subcutaneously for 3 consecutive days prior to SBI. We observed that VPC reduced brain edema and improved neurological function 24 h and 72 h after SBI. The expression of pro-inflammatory mediators in peri-resection brain tissue was reduced with VPC. Administration of Manoalide, a PLA2 inhibitor or Zileuton, a 5-LOX inhibitor with VPC reversed the protective effects of VPC against neuroinflammation. The current VPC regime induced local skin inflammatory reaction limited to subcutaneous injection site and elicited no other toxic effects. Our findings suggest that VPC reduces neuroinflammation and improves outcomes after SBI by activating PLA2/5-LOX/LTB4 cascade. VPC may be beneficial to reduce post-operative neuroinflammatory complications after brain surgeries.

5-LO inhibition ameliorates palmitic acid-induced ER stress, oxidative stress and insulin resistance via AMPK activation in murine myotubes.

Leukotriene B4 (LTB4) production via the 5-lipoxygenase (5-LO) pathway contributes to the development of insulin resistance in adipose and hepatic tissues, but the role of LTB4 in skeletal muscle is relatively unknown. Here, the authors investigated the role of LTB4 in C2C12 myotubes in palmitic acid (PA)-induced ER stress, inflammation and insulin resistance. PA (750 µM) evoked lipotoxicity (ER stress, oxidative stress, inflammation and insulin resistance) in association with LTB4 production. 5-LO inhibition reduced all the lipotoxic effects induced by PA. On the other hand, PA did not induce cysteinyl leukotrienes (CysLTs), which themselves had no effect on ER stress and inflammation. The beneficial effects of 5-LO suppression from PA-induced lipotoxicity were related with AMPK activation. In ob/ob mice, once daily oral administration of zileuton (50, 100 mg/kg) for 5 weeks improved insulin resistance, increased AMPK phosphorylation, and reduced LTB4 and ER stress marker expression in skeletal muscle. These results show that 5-LO inhibition by either zileuton or 5-LO siRNA protects C2C12 myotubes from PA-induced lipotoxicity, at least partly via AMPK activation, and suggest that the in vivo insulin-sensitizing effects of zileuton are in part attributable to its direct action on skeletal muscle via LTB4 downregulation followed by AMPK activation.

Anti-inflammatory and analgesic activity of carnosol and carnosic acid in vivo and in vitro and in silico analysis of their target interactions.

BACKGROUND AND PURPOSE: The diterpenoids carnosol (CS) and carnosic acid (CA) from Salvia spp. exert prominent anti-inflammatory activities but their molecular mechanisms remained unclear. Here we investigated the effectiveness of CS and CA in inflammatory pain and the cellular interference with their putative molecular targets. EXPERIMENTAL APPROACH: The effects of CS and CA in different models of inflammatory pain were investigated. The inhibition of key enzymes in eicosanoid biosynthesis, namely microsomal prostaglandin E2 synthase-1 (mPGES-1) and 5-lipoxygenase (5-LO) was confirmed by CS and CA, and we determined the consequence on the eicosanoid network in activated human primary monocytes and neutrophils. Molecular interactions and binding modes of CS and CA to target enzymes were analyzed by docking studies. KEY RESULTS: CS and CA displayed significant and dose-dependent anti-inflammatory and anti-nociceptive effects in carrageenan-induced mouse hyperalgesia 4 h post injection of the stimuli, and also inhibited the analgesic response in the late phase of the formalin test. Moreover, both compounds potently inhibited cell-free mPGES-1 and 5-LO activity and preferentially suppressed the formation of mPGES-1 and 5-LO-derived products in cellular studies. Our in silico analysis for mPGES-1 and 5-LO supports that CS and CA are dual 5-LO/mPGES-1 inhibitors. CONCLUSION AND IMPLICATIONS: In summary, we propose that the combined inhibition of mPGES-1 and 5-LO by CS and CA essentially contributes to the bioactivity of these diterpenoids. Our findings pave the way for a rational use of Salvia spp., traditionally used as anti-inflammatory remedy, in the continuous expanding context of nutraceuticals. LINKED ARTICLES: This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Effect of treatment with 5-lipoxygenase inhibitor VIA-2291 (atreleuton) on coronary plaque progression: a serial CT angiography study.

BACKGROUND: Inflammation has a key role in the process of atherosclerosis. Production of leukotrienes by 5-lipoxygenase has been linked to atherosclerotic plaques and cardiovascular events. HYPOTHESIS: In this study, a selective 5-LO inhibitor will slow plaque progression using serial cardiac computed tomographic angiography (CCTA). METHODS: Patients with recent acute coronary syndrome (ACS) were prospectively assigned to one of 3 VIA-2291 doses (25 mg, 50 mg, 100 mg) or placebo by oral administration. All groups underwent CCTA at baseline and at 6 months' follow-up. Plaque types such as low-attenuation plaque (LAP), fibro-fatty tissue (FF), fibro-calcified plaque (FC), and dense calcium plaque (DC) were measured based upon predefined density threshold, and changes from baseline CCTA were analyzed. RESULTS: The final analysis included 54 patients (age, 56 ± 9 years; 85.1% male) with CCTA at baseline and 24 weeks. Evaluating on treatment VIA-2291 (all 3 doses, n = 37) demonstrated significant reductions in plaque progression compared with placebo (n = 17). VIA-2291 significantly reduced LAP (5.9 ± 20.7 mm3 vs -9.7 ± 33.3 mm3 ), FF (11.1 mm3 ± 13.3 mm3 vs -0.9 ± 2.7 mm3 ), and FC (-0.1 ± 6.22 mm3 vs -14.3 ± 6.2 mm3 ; all P < 0.05) and retarded the progression of DC (3.9 ± 3.2 mm3 vs 0.2 ± 0.4 mm3 ) compared with placebo. CONCLUSIONS: VIA-2291 resulted in slowed plaque progression compared with placebo across different plaque subtypes in patients with recent ACS (http://ClinicalTrials.gov NCT00358826).

The 5-lipoxygenase inhibitor RF-22c potently suppresses leukotriene biosynthesis in cellulo and blocks bronchoconstriction and inflammation in vivo.

5-Lipoxygenase (5-LO) catalyzes the first two steps in leukotriene (LT) biosynthesis. Because LTs play pivotal roles in allergy and inflammation, 5-LO represents a valuable target for anti-inflammatory drugs. Here, we investigated the molecular mechanism, the pharmacological profile, and the in vivo effectiveness of the novel 1,2-benzoquinone-featured 5-LO inhibitor RF-22c. Compound RF-22c potently inhibited 5-LO product synthesis in neutrophils and monocytes (IC50⩾22nM) and in cell-free assays (IC50⩾140nM) without affecting 12/15-LOs, cyclooxygenase (COX)-1/2, or arachidonic acid release, in a specific and reversible manner, supported by molecular docking data. Antioxidant or iron-chelating properties were not evident for RF-22c and 5-LO-regulatory cofactors like Ca(2+) mobilization, ERK-1/2 activation, and 5-LO nuclear membrane translocation and interaction with 5-LO-activating protein (FLAP) were unaffected. RF-22c (0.1mg/kg; i.p.) impaired (I) bronchoconstriction in ovalbumin-sensitized mice challenged with acetylcholine, (II) exudate formation in carrageenan-induced paw edema, and (III) zymosan-induced leukocyte infiltration in air pouches. Taken together, RF-22c is a highly selective and potent 5-LO inhibitor in intact human leukocytes with pronounced effectiveness in different models of inflammation that warrants further preclinical analysis of this agent as anti-inflammatory drug.

Co-administration of 3-Acetyl-11-Keto-Beta-Boswellic Acid Potentiates the Protective Effect of Celecoxib in Lipopolysaccharide-Induced Cognitive Impairment in Mice: Possible Implication of Anti-inflammatory and Antiglutamatergic Pathways.

Neuro-inflammation is known to initiate the underlying pathogenesis of several neurodegenerative disorders which may progress to cognitive, behavioral, and functional impairment. Boswellia serrata is a well-known powerful anti-inflammatory agent used to treat several inflammatory diseases. The aim of the current study is to investigate the effect of the combination therapy of 3-acetyl-11-keto-ß-boswellic acid (AKBA), a 5-lipoxygenase (5-LOX) inhibitor and celecoxib, and a selective cyclooxygenase-2 (COX-2) inhibitor as dual enzyme inhibitors compared to monotherapies with celecoxib and AKBA. Cognitive dysfunction is induced by intraperational injection of lipopolysaccharide (LPS) in mice. Radial maze, Y maze, and novel object recognition (NOR) were performed to evaluate the possible behavioral changes. Moreover, estimation of glutamate and tumor necrosis factor-alpha (TNF-α), as well as an immunohistochemical investigation of amyloid beta peptide (Aß) was performed to evaluate the molecular changes that followed the LPS or drug treatment. The results showed that the combination therapy of AKBA and celecoxib reversed the behavioral and molecular changes caused by LPS cognitive dysfunction model that predispose cognitive dysfunction in mice. This study showed the effectiveness of the dual therapy with AKBA and celecoxib as anti-inflammatory, antiglutamatergic, and anti-amyloidogenic agents in the management of cognitive dysfunction.

Gastrointestinal Motility Variation and Implications for Plasma Level Variation: Oral Drug Products.

The oral route of administration is still by far the most ubiquitous method of drug delivery. Development in this area still faces many challenges due to the complexity and inhomogeneity of the gastrointestinal environment. In particular, dosing unpredictably relative to motility phase means the gastrointestinal environment is a random variable within a defined range. Here, we present a mass balance analysis that captures this variation and highlights the effects of gastrointestinal motility, exploring what impacts it ultimately has on plasma levels and the relationship to bioequivalence for high solubility products with both high and low permeability (BCS I and III). Motility-dependent compartmental absorption and transit (MDCAT) mechanistic analysis is developed to describe the underlying fasted state cyclical motility and how the contents of the gastrointestinal tract are propelled.

Combined Inhibition of Histamine H1 Receptors and Leukotrienes Reduces Compound 48/80-Induced Contraction of the Human Bronchus in vitro.

BACKGROUND/AIMS: Bronchial asthma continues to be a big challenge to therapy. Mast cells play an important role in allergic asthma. Histamine and leukotrienes are established mast cell mediators, but antihistamines currently play no role in asthma therapy. METHODS: Human bronchial strips were exposed to the mast cell activator compound 48/80 (200 µg/ml) in isolated organ experiments. RESULTS: The contractile response was not inhibited by the H1 receptor antagonist antihistamine chloropyramine (0.3 µmol/l), the leukotriene cys-LT1 receptor antagonist MK 571 (3 µmol/l), the 5-lipoxygenase inhibitor MK 886 (5 µmol/l), the cyclo-oxygenase inhibitor indomethacin (5 µmol/l), tetrodotoxin, or atropine. Chloropyramine, combined with either MK 571 or MK 886 significantly reduced the response. CONCLUSION: A supra-additive effect is proposed for the antihistamine and the anti-leukotrienes, which might have relevance to human asthma therapy as well; such a combination deserves a large-scale clinical study. These data also indicate that substances like compound 48/80 should be denoted as mast cell activators rather than 'histamine liberators'.

Recurrent stuck mitral valve: eosinophilia an unusual pathology.

Eosinophilia is a very unusual and rare cause of thrombosis of prosthetic mitral valve. We report a 10-year-old male child of recurrent stuck prosthetic mitral valve. The child underwent mitral valve replacement for severe mitral regurgitation secondary to Rheumatic heart disease. He had recurrent prosthetic mitral valve thrombosis, despite desired INR levels. There was associated eosinophilia. The child was treated on the lines of tropical eosinophilia with oral prednisolone and diethylcarbamazine, the eosinophil count dropped significantly with no subsequent episode of stuck mitral valve. We discuss the management of recurrent stuck mitral valve and also eosinophilia as a causative factor for the same.

Inhibition of 5-lipoxygenase pathway attenuates acute liver failure by inhibiting macrophage activation.

This study aimed to investigate the role of 5-lipoxygenase (5-LO) in acute liver failure (ALF) and changes in macrophage activation by blocking it. ALF was induced in rats by administration of D-galactosamine (D-GalN)/lipopolysaccharide (LPS). Rats were injected intraperitoneally with AA-861 (a specific 5-LO inhibitor), 24 hr before D-GalN/LPS administration. After D-GalN/LPS injection, the liver tissue was collected for assessment of histology, macrophage microstructure, macrophage counts, 5-LO mRNA formation, protein expression, and concentration of leukotrienes. Serum was collected for detecting alanine aminotransferase (ALT), aspartate transaminase (AST), total bilirubin (Tbil), and tumor necrosis factor- (TNF-) α . Twenty-four hours after injection, compared with controls, ALF rats were characterized by widespread hepatocyte necrosis and elevated ALT, AST, and Tbil, and 5-LO protein expression reached a peak. Liver leukotriene B4 was also significantly elevated. However, 5-LO mRNA reached a peak 8 hr after D-GalN/LPS injection. Simultaneously, the microstructure of macrophages was changed most significantly and macrophages counts were increased significantly. Moreover, serum TNF- α was also elevated. By contrast, AA-861 pretreatment significantly decreased liver necrosis as well as all of the parameters compared with the rats without pretreatment. Macrophages, via the 5-LO pathway, play a critical role in ALF, and 5-LO inhibitor significantly alleviates ALF, possibly related to macrophage inhibition.