Impact of 5-Lipoxygenase Deficiency on Dopamine-Mediated Behavioral Responses.

The 5-lipoxygenase/leukotriene system has been implicated in both physiological and pathological states within the central nervous system. Understanding how this system interacts with the dopaminergic system could provide valuable insights into dopamine-related pathologies. This study focused on examining both motor and non-motor dopamine-related responses in 5-lipoxygenase/leukotriene-deficient mice. We used pharmacological agents such as amphetamine, apomorphine, and reserpine to challenge the dopaminergic system, evaluating their effects on prepulse inhibition reaction (PPI), general motor activity, and oral involuntary movements. Additionally, we analyzed striatal glial marker expression (GFAP and Iba-1) in reserpine-treated mice. The 5-lipoxygenase/leukotriene-deficient mice exhibited increased spontaneous locomotor activity, including both horizontal and vertical exploration, along with stereotyped behavior compared to wild-type mice. This hyperactivity was reduced by acute apomorphine treatment. Although basal PPI responses were unchanged, 5-lipoxygenase/leukotriene-deficient mice displayed a significant reduction in susceptibility to amphetamine-induced PPI disruption. Conversely, these mice were more vulnerable to reserpine-induced involuntary movements. There were no significant differences in the basal expression of striatal GFAP and Iba-1 positive cells between 5-lipoxygenase/leukotriene-deficient and wild-type mice. However, reserpine treatment significantly increased GFAP immunoreactivity in wild-type mice, an effect not observed in 5-lipoxygenase-deficient mice. Additionally, the percentage of activated microglia was significantly higher in reserpine-treated wild-type mice, an effect absents in 5-lipoxygenase/leukotriene-deficient mice. Our findings suggest that 5-lipoxygenase/leukotriene deficiency leads to a distinctive dopaminergic phenotype, indicating that leukotrienes may influence the modulation of dopamine-mediated responses.

Nordihydroguaiaretic Acid Affects Undifferentiated and Differentiated Neuroblastoma Cells Differently through Mechanisms that Impact on Cell Viability.

AIM: We aimed to investigate the mechanisms involved in the neurotoxic effects of NDGA on differentiated and undifferentiated human neuroblastoma cells (MSN), assessing cell viability, changes in the actin cytoskeleton, cell migration and the expression of the 5-LOX enzyme and the inhibitor of cell cycle progression p21WAF1/CIP1. BACKGROUND: High expression and activity of the lipoxygenase enzyme (LOX) have been detected in several tumors, including neuroblastoma samples, suggesting the use of LOX inhibitors as potential therapy molecules. Among these, the natural compound nordihydroguaiaretic acid (NDGA) has been extensively tested as an antiproliferative drug against diverse types of cancer cells. OBJECTIVE: In this study, we analyzed the toxic effect of NDGA on neuroblastoma cells at a dose that did not affect cell survival when they differentiated to a neuron-like phenotype and the potential mechanisms involved in the anticancer properties. METHODS: We exposed human neuroblastoma cells (MSN) to different concentrations of NDGA before and after a differentiation protocol with retinoic acid and nerve growth factor and analyzed cell viability, cell migration, actin cytoskeleton morphology and the levels of the cell cycle inhibitor p21WAF1/CIP1 and 5-LOX. RESULTS: We found that differentiated human neuroblastoma cells are more resistant to NDGA than undifferentiated cells. The toxic effects of NDGA were accompanied by reduced cell migration, changes in actin cytoskeleton morphology, induction of p21WAF1/CIP1 and decreased levels of the 5-LOX enzyme. CONCLUSION: This study provides new evidence regarding the potential use of NDGA to induce cell death in human neuroblastoma.

Evaluating the inhibitory activity of ferrocenyl Schiff bases derivatives on 5-lipoxygenase: Computational and biological studies.

In the search for new 5-LOX inhibitors, two ferrocenyl Schiff base complexes functionalized with catechol ((ƞ5-(E)-C5H4-NCH-3,4-benzodiol)Fe(ƞ5-C5H5) (3a)) and vanillin ((ƞ5-(E)-C5H4-NCH-3-methoxy-4-phenol)Fe(ƞ5-C5H5) (3b)) were obtained. Complexes 3a and 3b were biologically evaluated as 5-LOX inhibitors showed potent inhibition compared to their organic analogs (2a and 2b) and known commercial inhibitors, with IC50 = 0.17 ± 0.05 µM for (3a) and 0.73 ± 0.06 µM for (3b) demonstrated a highly inhibitory and potent effect against 5-LOX due to the incorporation of the ferrocenyl fragment. Molecular dynamic studies showed a preferential orientation of the ferrocenyl fragment toward the non-heme iron of 5-LOX, which, together with electrochemical and in-vitro studies, allowed us to propose a competitive redox deactivation mechanism mediated by water, where Fe(III)-enzyme can be reduced by the ferrocenyl fragment. An Epa/IC50 relationship was observed, and the stability of the Schiff bases was evaluated by SWV in the biological medium, observing that the hydrolysis does not affect the high potency of the complexes, making them interesting alternatives for pharmacological applications.

Effects of inhibition of 5-lipoxygenase and 12-lipoxygenase pathways on skeletal muscle fiber regeneration.

We investigated the effect of inhibition of 5-lipoxigenase (LOX) and 12-LOX pathways on the regeneration of skeletal muscle fibers after injury induced by a myotoxin (MTX) phospholipase A2 from snake venom in an in vivo experimental model. Gastrocnemius muscles of mice injected with MTX presented an increase in 5-LOX protein expression, while 12-LOX was found to be a constitutive protein of skeletal muscle. Animals that received oral treatments with 5-LOX inhibitor MK886 or 12-LOX inhibitor baicalein 30 min and 48 h after MTX-induced muscle injury showed a reduction in the inflammatory process characterized by a significant decrease of cell influx and injured fibers in the degenerative phase (6 and 24 h after injury). In the beginning of the regeneration process (3 days), mice that received MK886 showed fewer new basophilic fibers, suggesting fewer proliferative events and myogenic cell fusion. Furthermore, in the progression of tissue regeneration (14-21 days), the mice treated with 5-LOX inhibitor presented a lower quantity of central nucleus fibers and small-caliber fibers, culminating in a muscle that is more resistant to the stimulus of fatigue during muscle regeneration with a predominance of slow fibers. In contrast, animals early treated with the 12-LOX inhibitor presented functional fibers with higher diameters, less resistant to fatigue and predominance of fast heavy-chain myosin fibers as observed in control animals. These effects were accompanied by an earlier expression of myogenic factor MyoD. Our results suggest that both 5-LOX and 12-LOX pathways represent potential therapeutic targets for muscle regeneration. It appears that inhibition of the 5-LOX pathway represses only the degenerative process by reducing tissue inflammation levels. Meanwhile, inhibition of the 12-LOX pathway also favors the anticipation of maturation and earlier recovery of muscle fiber activity function after injury.

Systemic inhibition of 5-lipoxygenase by MK-886 exacerbates apical periodontitis bone loss in a mouse model.

BACKGROUND: To investigate if 5-LO selective inhibitor (MK-886) could be used for systemic treatment of experimentally induced apical periodontitis in a mouse model. METHODS: Twenty-four C57BL/6 mice were used. After coronal opening, a solution containing Escherichia coli LPS (1.0 µg/µL) was inoculated into the root canals of the lower and upper right first molars (n = 72 teeth). After 30 days apical periodontitis was established, and the animals were treated with MK-886 (5 mg/kg), a 5-LO inhibitor, for 7 and 14 days. The tissues were removed for histopathological and histometric analyses, evaluation of osteoclast number and gene expression for receptor activator of nuclear factor kappa-B (Tnfrsf11a), receptor activator of nuclear factor kappa-B ligand (Tnfsf11), osteoprotegerin (Tnfrsf11b), tartrate-resistant acid phosphatase (Acp5), matrix metalloproteinase-9 (Mmp9), cathepsin K (Ctsk) and calcitonin receptor (Calcr). Statistical data analysis was performed using Kruskal Wallis followed by Dunn's tests (α = 0.05). RESULTS: Administration of MK-886 for 7 days exerted no effect on apical periodontitis progression compared to LPS inoculation without treatment (p = 0.3549), while treatment for 14 days exacerbated bone loss (p < 0.0001). Administration of MK-886 enhanced osteoclastogenesis signaling and osteoclast formation within 7 days (p = 0.0005), but exerted no effect at 14 days (p > 0.9999). After 7 days of treatment, MK-886 induced mRNA expression for Acp5 (p = 0.0001), Calcr (p = 0.0003), Mmp9 (p = 0.0005) and Ctsk (p = 0.0008), however no effect in those gene expression was observed after 14 days (p > 0.05). CONCLUSION: Systemic treatment with MK-886 exacerbated LPS-induced apical periodontitis in a mouse model.

Biological screening of herbal extracts and essential oil from Plectranthus species: α-amylase and 5-lipoxygenase inhibition and antioxidant and anti-Candida potentials

Abstract The phenolic compound content, the antioxidant and α-amylase inhibition potentials of different extracts of the Plectranthus amboinicus, P. barbatus and P. ornatus were evaluated. We also evaluated the influence of plant growth and harvest time on the chemical composition of the essential oil (EO) of P. amboinicus, its antioxidant and anti-Candida activities and the α-amylase and lipoxygenase inhibitions. The turbo-extract of P. barbatus showed the greatest phenolic compound content and antioxidant activity. No α-amylase inhibition activity was observed in the analyzed extracts, but the turbo-extraction and refluxing extracts possessed high antioxidant activities. Protected cultivation and morning harvest conditions gave the best antioxidant activities, which was associated to the highest carvacrol content. P. amboinicus EO antioxidant activity could contribute to the reduction of oxidative stress in diabetes. Causal Candida strains of diabetic foot ulcers showed sensitivity to P. amboinicus EO. C. albicans and C. dubliniensis were the most sensitive of the selected Candida strains. Turbo-extracts or refluxing of the three species extracts and the EO of P. amboinicus should be considered as a potential candidate for the management the complications of type 2 diabetes.

Age-linked suppression of lipoxin A4 associates with cognitive deficits in mice and humans.

Age increases the risk for cognitive impairment and is the single major risk factor for Alzheimer's disease (AD), the most prevalent form of dementia in the elderly. The pathophysiological processes triggered by aging that render the brain vulnerable to dementia involve, at least in part, changes in inflammatory mediators. Here we show that lipoxin A4 (LXA4), a lipid mediator of inflammation resolution known to stimulate endocannabinoid signaling in the brain, is reduced in the aging central nervous system. We demonstrate that genetic suppression of 5-lipoxygenase (5-LOX), the enzyme mediating LXA4 synthesis, promotes learning impairment in mice. Conversely, administration of exogenous LXA4 attenuated cytokine production and memory loss induced by inflammation in mice. We further show that cerebrospinal fluid LXA4 is reduced in patients with dementia and positively associated with cognitive performance, brain-derived neurotrophic factor (BDNF), and AD-linked amyloid-ß. Our findings suggest that reduced LXA4 levels may lead to vulnerability to age-related cognitive disorders and that promoting LXA4 signaling may comprise an effective strategy to prevent early cognitive decline in AD.

Leukotriene B4 Loaded in Microspheres Inhibits Osteoclast Differentiation and Activation.

To investigate osteoclast formation in vivo and if leukotriene B4 (LTB4) loaded in microspheres (MS) could be used as a therapeutical strategy to promote a sustained delivery of the mediator and prevent osteoclast differentiation. Methods: In vivo, apical periodontitis was induced in mice to investigate osteoclast differentiation and signaling in absence of 5-lipoxygenase (5-LO). In vitro, LTB4-MS were prepared using an oil-in-water emulsion solvent extraction-evaporation process. Characterization and efficiency of LTB4 encapsulation were investigated. J774A.1 macrophages were cultured in the presence of monocyte colony-stimulating factor (M-CSF) and ligand for receptor activator of nuclear factor kappa B (RANKL) and then stimulated with LTB4-MS. Cytotoxicity, in vitro MS-LTB4 uptake, osteoclast formation and gene expression were measured. Results: We found that 5-LO negatively regulates osteoclastic formation in vivo during apical periodontitis development. In vitro, LTB4-MS were up-taken by macrophages and were not cytotoxic to the cells. LTB4-MS inhibited osteoclast formation and the synthesis of osteoclastogenic genes Acp5, Mmp9, Calcr and Ctsk. LTB4-MS inhibited differentiation of macrophages into an osteoclastic phenotype and cell activation under M-CSF and RANKL stimulus.

New insights into the antiviral activity of nordihydroguaiaretic acid: Inhibition of dengue virus serotype 1 replication.

BACKGROUND: Dengue virus (DENV) is considered one of the most important pathogens in the world causing 390 million infections each year. Currently, the development of vaccines against DENV presents some shortcomings and there is no antiviral therapy available for its infection. An important challenge is that both treatments and vaccines must be effective against all four DENV serotypes. Nordihydroguaiaretic acid (NDGA), isolated from Larrea divaricata Cav. (Zygophyllaceae) has shown a significant inhibitory effect on a broad spectrum of viruses, including DENV serotypes 2 and 4. PURPOSE: We evaluated the in vitro virucidal and antiviral activity of NDGA on DENV serotype 1 (DENV1), including the study of its mechanism of action, to provide more evidence on its antiviral activity. METHODS: The viability of viral particles was quantified by the plaque-forming unit reduction method. NDGA effects on DENV1 genome and viral proteins were evaluated by qPCR and immunofluorescence, respectively. Lysosomotropic activity was assayed using acridine orange and neutral red dyes. RESULTS: NDGA showed in vitro virucidal and antiviral activity against DENV1. The antiviral effect would be effective within the first 2 h after viral internalization, when the uncoating process takes place. In addition, we determined by qPCR that NDGA decreases the amount of intracellular RNA of DENV1 and, by immunofluorescence, the number of cells infected. These results indicate that the antiviral effect of NDGA would have an intracellular mechanism of action, which is consistent with its ability to be incorporated into host cells. Considering the inhibitory activity of NDGA on the cellular lipid metabolism, we compared the antiviral effect of two inhibitors acting on two different pathways of this type of metabolism: 1) resveratrol that inhibits the sterol regulatory element of binding proteins, and 2) caffeic acid that inhibits the 5-lipoxygenase (5-LOX) enzyme. Only caffeic acid produced an inhibitory effect on DENV1 infection. We studied the lysosomotropic activity of NDGA on host cells and found, for the first time, that this compound inhibited the acidification of cell vesicles which would prevent DENV1 uncoating process. CONCLUSION: The present work contributes to the knowledge of NDGA activity on DENV. We describe its activity on DENV1, a serotype different to those that have been already reported. Moreover, we provide evidence on which stage/s of the viral replication cycle NDGA exerts its effects. We suggest that the mechanism of action of NDGA on DENV1 is related to its lysosomotropic effect, which inhibits the viral uncoating process.

Cecropia pachystachya Trécul: identification, isolation of secondary metabolites, in silico study of toxicological evaluation and interaction with the enzymes 5-LOX and α-1-antitrypsin.

Cecropia pachystachya Tréc., popularly known as embaúba, belongs to the Cecropiaceae family and is used by the native population in the treatment of bronchitis, asthma, high blood pressure, fever, and as a diuretic. The pharmacological actions including anti-inflammatory, antioxidant, cardiotonic and sedative were previously reported. The objective of this study was to (1) isolate and identify bioactive compounds extracted from the ethanolic extract of C. pachystachya roots (ERCP), as well as (2) verify the affinity of these metabolites with the enzymes 5-lipoxygenase (5-LOX) and α-1-antitrypsin through in silico tests. Isolation and/or identification were performed using GC-MS, HPLC, Infrared (IR), and nuclear magnetic resonance (NMR) techniques. After isolation and identification of the active compounds, these substances were subjected to the in silico investigation that proceeded by performing PreADMET simulations and molecular docking calculations. The bioactive compounds identified were 1-(+)-ascorbic acid 2,6-dihexadecanoate, ethyl hexadecanoate, ethyl (9E,12E)-octadec-9,12-dienoate, ethyl (Z)-octadec-9-enoate and ethyl octadecanoate by GC-MS; chlorogenic acid, catechin, epicatechin, syringaldehyde by HPLC; ß-sitosterol, sitostenone, beccaridiol, tormentic acid, lupeol, α- and ß-amyrin by classical chromatography, IR, 1H and 13C NMR techniques. The ADMET (absorption, distribution, metabolism, excretion, and toxicity) properties were determined for each bioactive compound. Tormentic acid demonstrated a greater affinity for 5-LOX enzyme while sitostenone demonstrated a higher affinity for the α-1-antitrypsin enzyme. Our findings demonstrated a diverse range of secondary metabolites isolated from C. pachystachya that showed relevant interactions with the enzymes 5-LOX and α-1-antitrypsin. Thus, "embaúba" may be employed in in vivo experimental studies as a form of alternative treatment for chronic lung diseases.Abbreviations: ADT: Autodock Tools; BBB: Blood-brain barrier; CaCo2: Human colonic adenocarcinoma cells; CC: Classic/open Column; TLC: Thin Layer Chromatography; CD40: Differentiation Cluster 40; CENAUREMN: Centro Nordestino de Aplicação e Uso da Ressonância Magnética Nuclear; GC-MS: Gas Chromatography coupled to mass spectrometry; HPLC: High-Perfomance Liquid Chromatography; CYP2C9, CYP2C19, CYP2D6 and CYP3A4: Cytochrome P450 isoenzymes; COPD: Chronic Obstructive Pulmonary Disease; DRX-500: X-Ray Diffraction - 500; ERCP: Ethanolic extract of the roots of C. pachystachya; FAPEPI: Fundação de Amparo à Pesquisa do Piauí; HIA: Human Intestinal Absorption; IR: Infrared; Ki: Inhibition constant; 5-LOX: 5-Lipoxygenase; mM: miliMolar; nM: nanoMolar; OECD423: acute toxic class method; PDB: Protein Data Bank; P-gP: P-glycoprotein; PM2,5: Small inhalable particles 2,5; PPB: Plasm Protein Binding; PreADMET: Prediction Absorption, Distribution, Metabolization, Excretion and Toxicity; NMR: Nuclear Magnetic Resonance; +S9: with metabolic activation; -S9: no metabolic activation; SisGen: Sistema Nacional de Gestão de Patrimônio Genético e do Conhecimento Tradicional Associado; RT: Retention time; TA100: Ames test with TA100 cells line; TA1535: Ames test with cells of the TA1535 cell line; UESPI: State University of Piauí; V79: lung fibroblast cells; ΔG: Gibbs free energy (Kcal/mol); µM: microMolar.

Active Compounds in Zingiber officinale as Possible Redox Inhibitors of 5-Lipoxygenase Using an In Silico Approach.

5-Lipoxygenase (5-LOX) converts arachidonic acid to lipidic inflammatory mediators such as leukotrienes (LTs). In diseases such as asthma, LTs contribute to a physiopathology that could be reverted by blocking 5-LOX. Natural products with anti-inflammatory potential such as ginger have been used as nutraceuticals since ancient times. 6-Gingerol and 6-shogaol are the most abundant compounds in the ginger rhizome; they possess anti-inflammatory, antioxidant, and chemopreventive properties. In the present study, 6-gingerol and 6-shogaol structures were analyzed and compared with two commercial 5-LOX inhibitors (zileuton and atreleuton) and with other inhibitor candidates (3f, NDGA, CP 209, caffeic acid, and caffeic acid phenethyl ester (CAPE)). The pharmacokinetics and toxicological properties of 6-gingerol, 6-shogaol, and the other compounds were evaluated. Targeted molecular coupling was performed to identify the optimal catalytic pocket for 5-LOX inhibition. The results showed that 6-gingerol and 6-shogaol follow all of the recommended pharmacokinetic parameters. These compounds could be inhibitors of 5-LOX because they present specific interactions with the residues involved in molecular inhibition. The current study demonstrated the potential of 6-gingerol and 6-shogaol as anti-inflammatory agents that inhibit 5-LOX, as they present a high level of performance in the toxicological analysis and could be catabolized by the cytochrome p450 enzymatic complex; however, 6-gingerol was superior in safety compared to 6-shogaol.

Toxoplasma gondii Infection Decreases Intestinal 5-Lipoxygenase Expression, while Exogenous LTB4 Controls Parasite Growth.

5-Lipoxygenase (5-LO) is an enzyme required for the production of leukotrienes and lipoxins and interferes with parasitic infections. In vitro, Toxoplasma gondii inhibits leukotriene B4 (LTB4) production, and mice deficient in 5-LO are highly susceptible to infection. The aim of this study was to investigate the effects of the pharmacological inhibition of the 5-LO pathway and exogenous LTB4 supplementation during experimental toxoplasmosis. For this purpose, susceptible C57BL/6 mice were orally infected with T. gondii and treated with LTB4 or MK886 (a selective leukotriene inhibitor through inhibition of 5-LO-activating protein [FLAP]). The parasitism, histology, and immunological parameters were analyzed. The infection decreased 5-LO expression in the small intestine, and treatment with MK886 reinforced this reduction during infection; in addition, MK886-treated infected mice presented higher intestinal parasitism, which was associated with lower local interleukin-6 (IL-6), interferon gamma (IFN-γ), and tumor necrosis factor (TNF) production. In contrast, treatment with LTB4 controlled parasite replication in the small intestine, liver, and lung and decreased pulmonary pathology. Interestingly, treatment with LTB4 also preserved the number of Paneth cells and increased α-defensins expression and IgA levels in the small intestine of infected mice. Altogether, these data demonstrated that T. gondii infection is associated with a decrease in 5-LO expression, and on the other hand, treatment with the 5-LO pathway product LTB4 resulted in better control of parasite growth in the organs, adding to the knowledge about the pathogenesis of T. gondii infection.

Processo de reparo alveolar frente à administração de bifosfonato nitrogenado: avaliação comparativa em camundongos 129/Sv-WT e 129/Sv 5-LOKO / Alveolar bone repair of mice under administration of bisphosphonate containing nitrogen: comparative investigation between 129/Sv-WT and 129/Sv 5- LOKO

A instalação das osteonecroses dos maxilares(OM) tem sido relacionada ao uso crônico de medicamentos antirreabsortivos indicados para doenças e distúrbios do metabolismo ósseo, como os bifosfonatos nitrogenados (nBF), especialmente quando associados a intervenções cirúrgicas-odontológicas. Deste modo, especulase que a instalação desta doença não ocorre somente devido à condição do tecido ósseo e sua capacidade reacional, mas principalmente pela sua condição de defesa imunológica. O presente estudo tem como objetivo analisar o padrão de reparo ósseo de alvéolos dentários de incisivos superiores recém-extraídos de camundongos 129/Sv geneticamente modificados (knockouts ­ KO) para a enzima 5-lipoxigenase (5-LO), os quais apresentam fenótipo esqueletal osteopetrótico, comparando-os com tipo selvagem (Wild Type ­ WT), com e sem administração de nBF. Para tanto foram utilizados 80 camundongos machos com idades variando entre 8 e 10 semanas, sendo 46 animais 129/Sv WT e 46 animais 129/Sv 5-LOKO, os quais foram submetidos à exodontia do dente incisivo superior direito e divididos em quatro grupos de acordo com o tratamento: Grupo WT ­ 0,1 ml de soro fisiológico 0,9%, Grupo WT-ZL ­ 0,5 mg/Kg de ácido zoledrônico (ZL), Grupo 5- LOKO - 0,1 ml de soro fisiológico 0,9%, Grupo 5-LOKO-ZL ­ 0,5 mg/Kg de ZL, sendo ambas soluções administradas intraperitonealmente (IP) 1x por semana até o final do experimento. Após os períodos de 7, 14 e 30 dias, cinco animais de cada grupo foram submetidos à eutanásia para remoção das maxilas direitas contendo os alvéolos para as análises histopatológica, histomorfométrica e imuno-histoquímica para COX-2, OPG, RANKL e TRAP. Os resultados não mostraram diferença significativa para a quantidade de matriz óssea entre os grupos WT, KO e WT-ZL. Contudo, foi observado que o grupo KO-ZL apresentou significativamente menos matriz óssea em todos os períodos quando comparado com WT-ZL, além de maior quantidade de células inflamatórias no 14 e 30 dias. Observou-se aumento significativo de células COX-2+ no grupo WT aos 14 dias em comparação com os demais. Detectou-se aumento de OPG ao final do reparo em todos os grupos. Aumento significativo de RANKL foi observado no grupo KO aos 7 dias, em comparação com 5-LOKO, sendo que ao final do reparo WT-ZL mostrou células RANKL+ significativamente elevadas em comparação com WT e KO-ZL. No entanto, somente aos 14 dias observou-se aumento significativo de células TRAP+ nos grupos WT e WT-ZL em comparação com KO e KO-ZL. A partir destes resultados, pode-se concluir que os animais 5-LOKO apresentaram formação óssea precoce em alvéolos dentários pós-exodontia comparados com os animais WT. No entanto, os efeitos do ZL foram mais deletérios nos camundongos 5-LOKO, possivelmente pela influência da droga e efeitos da inibição desta enzima nos eventos inflamatórios no curso do reparo(AU)

Osteonecrosis of the jaws has been related to the chronic use of antiresorptive drugs indicated for diseases and disorders of bone metabolism, such as nitrogenous bisphosphonates (nBP), especially when associated with surgical-dental interventions. Thus, it is speculated that the onset of this disease does not occur only due to the condition of the bone tissue and its reactive capacity, but mainly due to its immunological defense condition. The present study aimed to analyze the bone repair pattern of dental alveoli of maxillary incisors recently extracted from 129/Sv 5- LOKO mice, which had an osteopetrotic skeletal phenotype, comparing them with wild type, 129/Sv WT, with and without administration of nBP. For that, 80 male mice were used with ages varying between 8 and 10 weeks, being 46 animals 129/Sv WT and 40 animals 129/Sv 5-LOKO, which were submitted to the extraction of the upper right incisor tooth and divided into four groups of according to treatment: WT Group - 0.1 ml of 0.9% saline solution, WT-ZL Group - 0.5 mg/Kg of zoledronic acid, Group 5- LOko - 0.1 ml of 0.9 saline solution %, Group 5-LOko-ZL ­ 0.5 mg/Kg of zoledronic acid, both solutions being administered intraperitoneally (IP) 1x a week until the end of the experiment. After periods of 7, 14 and 30 days, five animals from each group were euthanized to remove the right jaws containing the alveoli. They were immediately fixed in order to be prepared for the following methodological procedures: histotechnical processing for making histological slides stained with hematoxylin and eosin and immunohistochemical No significant difference was found for the amount of bone matrix between the WT, KO and WT-ZL groups. However, it was observed that the KO-ZL group presented significantly less bone matrix in all periods when compared to WT-ZL, in addition to a greater amount of inflammatory cells at 14 and 30 days. There was a significant increase in COX-2+ cells in the WT group at 14 days compared to the others. An increase in OPG was detected at the end of the repair in all groups. Significant increase in RANKL was observed in the KO group at 7 days, compared to 5-LOKO, and at the end of repair WT-ZL showed significantly elevated RANKL+ cells compared to WT and KO-ZL. However, only at 14 days there was a significant increase in TRAP+ cells in the WT and WT-ZL groups compared to KO and KO-ZL. From these results, it can be concluded that 5-LOKO animals showed early bone formation in post-extraction tooth sockets compared to WT animals. However, the effects of ZL were more deleterious in 5-LOKO mice, possibly due to the influence of the drug and the effects of inhibition of this enzyme on inflammatory events in the course of repair(AU)

Alveolar socket healing in 5-lipoxygenase knockout aged female mice treated or not with high dose of zoledronic acid.

This study investigated the role 5-lypoxigenase (5-LO) on alveolar socket healing in aged female mice treated with zoledronic acid (ZL). Forty 129/Sv female mice (64-68 weeks old), 20 wild type (WT) and 20 5-LO knockout (5LOKO) were equally distributed according to ZL treatment: WT Control, WT ZL, 5LOKO Control, and 5LOKO ZL. ZL groups were treated with an intraperitoneal injection of 250 µg/Kg of ZL, while controls were treated with saline. Treatments were administered once a week, starting four weeks before surgery for tooth extraction and until 7 and 21 days post-surgery. Mice were euthanized for a comprehensive microscopic analysis (microCT, histomorphometry and immunohistochemistry). WT ZL mice presented intense inflammatory infiltrate (7 days), delayed bone formation (21 days), reduced collagenous matrix quality, and a deficiency in Runx-2 + , TRAP + , and macrophages as compared to controls. 5LOKO ZL animals presented decreased number of Runx-2 + cells in comparison to 5LOKO Control at 7 days, but no major changes in bone healing as compared to WT or 5LOKO mice at 21 days. The knockout of 5LO favored intramembranous bone healing in aged female mice, with a direct impact on inflammatory response and bone metabolism on the development of ONJ-like lesions.

Lack of 5-lipoxygenase in intramembranous and endochondral 129Sv mice skeleton and intramembranous healing.

OBJECTIVE: To analyze the lack of 5-lipoxygenase (5LO) on dental socket healing and post-natal phenotype of intramembranous and endochondral bones. DESIGN: Wild type (WT) 129/SvEv (n = 20) and 5LO knockout (5LOKO) (n = 20) male mice underwent tooth extraction of the upper right incisor and were euthanized after 7, 14, and 30 day time points for the evaluation of dental socket healing and histological phenotyping of intramembranous (IM) and endochondral (EC) bones. Microscopic analysis of alveolar sockets included histopathological description, histomorphometry, and immunohistochemistry for 5LO, cyclooxygenase 2 (COX2), and tartrate resistant acid phosphatase (TRAP). RESULTS: Histological phenotyping revealed thicker cortical bone in EC bones (femur and vertebra) of 5LOKO mice compared to WTs, with no differences in collagenous content. Although dental socket healing was similarly observed in both groups, WT mice revealed increased numbers of COX-2+ and 5LO+ cells during bone maturing stage, with a decrease of TRAP+ cells at day 30. On the other hand, an increased quantity of fibroblasts was observed at day 7 in 5LOKO group, as well as increased inflammatory infiltrate and significantly decreased TRAP+ cells at final stages of alveolar socket healing in comparison to WTs. CONCLUSIONS: The lack of 5LO in 5LOKO mice resulted in thicker cortical of EC, but not of IM post natal bones. Furthermore, genetic deletion of 5LO in the 5LOKO mice directly affected the inflammatory response during socket healing, influencing initial and late phases of bone repair in a model of post-tooth extraction in 129Sv WT and 5LOKO mice.

LTB4-Driven Inflammation and Increased Expression of ALOX5/ACE2 During Severe COVID-19 in Individuals With Diabetes.

Diabetes is a known risk factor for severe coronavirus disease 2019 (COVID-19), the disease caused by the new coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, there is a lack of knowledge about the mechanisms involved in the evolution of COVID-19 in individuals with diabetes. We aimed to evaluate whether the chronic low-grade inflammation of diabetes could play a role in the development of severe COVID-19. We collected clinical data and blood samples of patients with and without diabetes hospitalized for COVID-19. Plasma samples were used to measure inflammatory mediators and peripheral blood mononuclear cells, for gene expression analysis of the SARS-CoV-2 main receptor system (ACE2/TMPRSS2), and for the main molecule of the leukotriene B4 (LTB4) pathway (ALOX5). We found that diabetes activates the LTB4 pathway and that during COVID-19 it increases ACE2/TMPRSS2 as well as ALOX5 expression. Diabetes was also associated with COVID-19-related disorders, such as reduced oxygen saturation as measured by pulse oximetry/fraction of inspired oxygen (FiO2) and arterial partial pressure of oxygen/FiO2 levels, and increased disease duration. In addition, the expressions of ACE2 and ALOX5 are positively correlated, with increased expression in patients with diabetes and COVID-19 requiring intensive care assistance. We confirmed these molecular results at the protein level, where plasma LTB4 is significantly increased in individuals with diabetes. In addition, IL-6 serum levels are increased only in individuals with diabetes requiring intensive care assistance. Together, these results indicate that LTB4 and IL-6 systemic levels, as well as ACE2/ALOX5 blood expression, could be early markers of severe COVID-19 in individuals with diabetes.

The role of 5-lipoxygenase in the pathophysiology of COVID-19 and its therapeutic implications.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, known as coronavirus disease 2019 (COVID-19) causes cytokine release syndrome (CRS), leading to acute respiratory distress syndrome (ARDS), acute kidney and cardiac injury, liver dysfunction, and multiorgan failure. Although several studies have discussed the role of 5-lipoxygenase (5-LOX) in viral infections, such as influenzae and SARS, it remains unexplored in the pathophysiology of COVID-19. 5-LOX acts on free arachidonic acid (AA) to form proinflammatory leukotrienes (LTs). Of note, numerous cells involved with COVID-19 (e.g., inflammatory and smooth muscle cells, platelets, and vascular endothelium) widely express leukotriene receptors. Moreover, 5-LOX metabolites induce the release of cytokines (e.g., tumour necrosis factor-α [TNF-α], interleukin-1α [IL-1α], and interleukin-1ß [IL-1ß]) and express tissue factor on cell membranes and activate plasmin. Since macrophages, monocytes, neutrophils, and eosinophils can express lipoxygenases, activation of 5-LOX and the subsequent release of LTs may contribute to the severity of COVID-19. This review sheds light on the potential implications of 5-LOX in SARS-CoV-2-mediated infection and the anticipated therapeutic role of 5-LOX inhibitors.

5-lipoxygenase- and Glucocorticoid-dependent eosinophilia in a novel surgical model in mice.

BACKGROUND: Subcutaneous implants of heat-coagulated egg white (egg white implants, EWI) induce intense local eosinophilia and prime for hyperreactivity following airway ovalbumin challenge. The roles of allergen sensitization, surgical trauma-induced glucocorticoids, and the 5-lipoxygenase (5-LO) pathway were hitherto unexplored in this model, in which quantitative recovery and large-scale purification of the eosinophils from the inflammatory site for functional and immunopharmacological studies are difficult to achieve. METHODS: We overcame this limitation by shifting the implantation site to the peritoneal cavity (EWIp), thereby enabling quantitative leukocyte retrieval. RESULTS: By day 7 post-surgery, eosinophil counts reached ~ 30% of all leukocytes recovered. Eosinophilia was prevented by: a) induction of allergen-specific oral tolerance to ovalbumin, the main allergen in egg white; b) inactivation of the 5-lipoxygenase pathway; c) blockade of endogenous glucocorticoid signaling by pretreatment with metirapone plus mifepristone before surgery. Highly purified eosinophils (~99% pure) could be obtained from the peritoneal exudate of EWIp-carrier mice in 2 simple, antibody-free steps. Preparative-scale yields, suitable for most biochemical, pharmacological, and molecular applications, were routinely obtained, and could be further enhanced through addition of pre-or post-surgery immunization steps (active or adoptive). The recovered eosinophils were fully functional in vivo, as demonstrated by the transfer of purified eosinophils into eosinophil-deficient Δdbl-GATA-1-KO mice, which upon subsequent challenge with eotaxin-1 present secondary accumulation of neutrophils, but not of mononuclear phagocytes. CONCLUSION: These findings document glucocorticoid-, allergen- and 5-lipoxygenase-dependent eosinophilia, which makes EWIp carriers an abundant source of pure, nontransgenic eosinophils for immunopharmacological studies.

First report of antiviral activity of nordihydroguaiaretic acid against Fort Sherman virus (Orthobunyavirus).

The genus Orthobunyavirus are a group of viruses within arbovirus, with a zoonotic cycle, some of which could lead to human infection. A characteristic of these viruses is their lack of antiviral treatment or vaccine for its prevention. The objective of this work was to study the in vitro antiviral activity of nordihydroguaiaretic acid (NDGA), the most important active compound of Larrea divaricata Cav. (Zigophyllaceae), against Fort Sherman virus (FSV) as a model of Orthobunyavirus genus. At the same time, the effect of NDGA as a lipolytic agent on the cell cycle of this viral model was assessed. The method of reducing plaque forming units on LLC-MK2 cells was used to detect the action of NDGA on CbaAr426 and SFCrEq231 isolates of FSV. NDGA did not show virucidal effect, but it had antiviral activity with a similar inhibition in both isolates, which was dose dependent. It was established that the NDGA has a better inhibition 1-h post-internalization (p.i.), showing a different behavior in each isolate, which was dependent upon the time p.i. Since virus multiplication is dependent on host cell lipid metabolism, the antiviral effect of NDGA has been previously related to its ability to disturb the lipid metabolism, probably by interfering with the 5-lipoxigenase (5-LOX) and the sterol regulatory element-binding proteins (SREBP) pathway. We determined by using caffeic acid, a 5-LOX inhibitor, that the inhibition of this enzyme negatively affected the FSV replication; and by means of resveratrol, a SREBP1 inhibitor, it was showed that the negative regulation of this pathway only had action on the SFCrEq231 reduction. In addition, it was proved that the NDGA acts intracellularly, since it showed the ability to incorporate into LLC-MK2 cells. The information provided in this work converts the NDGA into a compound with antiviral activity in vitro against FSV (Orthobunyavirus), which can be subjected to structural modifications in the future to improve the activity.

Tagitinin F has anti-inflammatory, anti-nociceptive and anti-matrix metalloproteinase properties: An in silico, in vitro and in vivo study.

Sesquiterpene lactones (SL) are natural bioactive molecules indicated as potential scaffolds for anti-inflammatory and analgesic drug design. However, their anti-inflammatory applicability remains underestimated since the impact of SL on inflammatory nociception and tissue repair are overlooked. Thus, we used an integrated in silico, in vitro and in vivo framework to investigate the impact of tagitinin F (TAG-F) on lipopolysaccharide (LPS)-challenged macrophages, excisional skin wounds, and carrageenan-induced paw edema and mechanical hyperalgesia in mice. RAW 264.7 macrophages in culture were challenged with LPS and treated with TAG-F (5, 10, 50 and 100 µM). The paw of BALB/c mice was injected with carrageenan and treated with 0.5% and 1% TAG-F. Excisional wounds were also produced in BALB/c mice and treated with 0.5% and 1% TAG-F. Our results indicated a consistent concentration-dependent downregulation in 5-lipoxygenase, cyclooxygenase 1 and 2 (COX-1 and COX-2), matrix metalloproteinase 1 and 2 (MMP-1 and MMP-2) activities; as well as attenuation in prostaglandin E2 (PGE2), leukotriene B4 (LTB4) and tumor necrosis factor-α (TNF-α) production in both in vitro and in vivo models. In vivo, TAG-F also attenuated carrageenan-induced paw edema and mechanical hyperalgesia in mice. From the excisional skin wound, TAG-F was still effective in reducing neutrophils and macrophages infiltration and stimulating collagen deposition in the scar tissue, accelerating tissue maturation. Together, our findings indicate that the anti-inflammatory effect of TAG-F is more comprehensive than previously suggested, exerting a significant impact on the control of edema, inflammatory pain and modulating central metabolic processes linked to skin wound healing.