Oleic acid exhibits an expressive anti-inflammatory effect in croton oil-induced irritant contact dermatitis without the occurrence of toxicological effects in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Cutaneous inflammatory diseases, such as irritant contact dermatitis, are usually treated with topical corticosteroids, which cause systemic and local adverse effects limiting their use. Thus, the discovery of new therapeutic alternatives able to effectively treat skin inflammatory disorders, without causing adverse effects, is urgently needed. AIM OF THE STUDY: To investigate the topical anti-inflammatory effect of oleic acid (OA), a monounsaturated fatty acid, into Pemulen® TR2-based semisolid dosage forms, employing a croton oil-induced irritant contact dermatitis model in mice. MATERIALS AND METHODS: Male Swiss mice were submitted to skin inflammation protocols by acute and repeated applications of croton oil. The anti-inflammatory activity of Pemulen® TR2 hydrogels containing OA was evaluated by assessing oedema, inflammatory cell infiltration, and pro-inflammatory cytokine IL-1ß levels. The mechanisms of action of OA were evaluated using cytokine IL-1ß application or pretreatment with the glucocorticoid antagonist mifepristone. Possible toxic effects of OA were also assessed. RESULTS: Pemulen® TR2 3% OA inhibited the acute ear oedema [maximal inhibition (Imax) = 76.41 ± 5.69%], similarly to dexamethasone (Imax = 84.94 ± 2.16%), and also inhibited ear oedema after repeated croton oil application with Imax = 85.75 ± 3.08%, similar to dexamethasone (Imax = 81.03 ± 4.66%) on the day 7 of the experiment. Croton oil increased myeloperoxidase activity, which was inhibited by Pemulen® TR2 3% OA (Imax = 71.37 ± 10.97%) and by 0.5% dexamethasone (Imax = 96.31 ± 3.73%). Pemulen® TR2 3% OA also prevented the increase in pro-inflammatory cytokine IL-1ß levels induced by croton oil (Imax = 94.18 ± 12.03%), similar to 0.5% dexamethasone (Imax = 87.21 ± 10.58%). Besides, both Pemulen® TR2 3% OA and 0.5% dexamethasone inhibited IL-1ß-induced ear oedema with an Imax of 80.58 ± 2.45% and 77.46 ± 1.92%, respectively. OA and dexamethasone anti-inflammatory effects were prevented by 100% and 91.43 ± 5.43%, respectively, after pretreatment with mifepristone. No adverse effects were related to Pemulen® TR2 3% OA administration. CONCLUSIONS: OA demonstrated anti-inflammatory efficacy similar to dexamethasone, clinically used to treat skin inflammatory conditions, without presenting adverse effects.

Natural Extracts Abolished Lipid Accumulation in Cells Harbouring non-favourable PNPLA3 genotype.

Background & aims. G-allele of PNPLA3 (rs738409) favours triglycerides accumulation and steatosis. In this study, we examined the effect of quercetin and natural extracts from mushroom and artichoke on reducing lipid accumulation in hepatic cells. MATERIAL AND METHODS: Huh7.5 cells were exposed to oleic acid (OA) and treated with quercetin and extracts to observe the lipid accumulation, the intracellular-TG concentration and the LD size. Sterol regulatory element binding proteins-1 (SREBP-1), peroxisome proliferator-activated receptor (PPARα-γ) and cholesterol acyltransferase (ACAT) gene expression levels were analysed. RESULTS: Quercetin decreased the intracellular lipids, LD size and the levels of intracellular-TG through the down-regulation of SREBP-1c, PPARγ and ACAT1 increasing PPARα. The natural-extracts suppressed OA-induced lipid accumulation and the intracellular-TG. They down-regulate the hepatic lipogenesis through SREBP-1c, besides the activation of lipolysis through the increasing of PPARα expression. CONCLUSIONS: Quercetin and the aqueous extracts decrease intracellular lipid accumulation by down-regulation of lipogenesis and up-regulation of lipolysis.

Acute Respiratory Distress Syndrome: Role of Oleic Acid-Triggered Lung Injury and Inflammation.

Lung injury especially acute respiratory distress syndrome (ARDS) can be triggered by diverse stimuli, including fatty acids and microbes. ARDS affects thousands of people worldwide each year, presenting high mortality rate and having an economic impact. One of the hallmarks of lung injury is edema formation with alveoli flooding. Animal models are used to study lung injury. Oleic acid-induced lung injury is a widely used model resembling the human disease. The oleic acid has been linked to metabolic and inflammatory diseases; here we focus on lung injury. Firstly, we briefly discuss ARDS and secondly we address the mechanisms by which oleic acid triggers lung injury and inflammation.

Acute lung injury induced by the intravenous administration of cigarette smoke extract.

OBJECTIVE: To investigate the acute effects of intravenous administration of cigarette smoke extract (CSE) on histological, inflammatory, and respiratory function parameters in rats, as well as to compare this potential acute lung injury (ALI) model with that with the use of oleic acid (OA). METHODS: We studied 72 Wistar rats, divided into four groups: control (those injected intravenously with saline); CSE (those injected intravenously with CSE and saline); OA (those injected intravenously with saline and OA); and CSE/OA (those injected intravenously with CSE and OA). RESULTS: Mean lung compliance was significantly lower in the OA and CSE/OA groups (2.12 ± 1.13 mL/cmH2O and 1.82 ± 0.77 mL/cmH2O, respectively) than in the control group (3.67 ± 1.38 mL/cmH2O). In bronchoalveolar lavage fluid, the proportion of neutrophils was significantly higher in the OA and CSE/OA groups than in the control group, as was the activity of metalloproteinases 2 and 9. Pulmonary involvement, as assessed by morphometry, was significantly more severe in the OA and CSE/OA groups (72.9 ± 13.8% and 77.6 ± 18.0%, respectively) than in the control and CSE groups (8.7 ± 4.1% and 32.7 ± 13.1%, respectively), and that involvement was significantly more severe in the CSE group than in the control group. CONCLUSIONS: The intravenous administration of CSE, at the doses and timing employed in this study, was associated with minimal ALI. The use of CSE did not potentiate OA-induced ALI. Additional studies are needed in order to clarify the potential role of this model as a method for studying the mechanisms of smoking-induced lung injury.

Lesão pulmonar aguda induzida pela administração endovenosa de extrato da fumaça do cigarro / Acute lung injury induced by the intravenous administration of cigarette smoke extract

OBJETIVO: Investigar os efeitos agudos da administração endovenosa de extrato da fumaça do cigarro (EFC) em parâmetros funcionais respiratórios, inflamatórios e histológicos em ratos e comparar esse potencial modelo de lesão pulmonar aguda (LPA) com aquele com o uso de ácido oleico (AO). MÉTODOS: Foram estudados 72 ratos Wistar machos divididos em quatro grupos: tratados somente com soro fisiológico (SF; grupo controle); tratados com EFC e SF (grupo EFC); tratados com SF e AO (grupo AO); e tratados com EFC e AO (grupo EFC/AO). RESULTADOS: As médias de complacência foram significantemente menores nos grupos AO e EFC/AO (2,12 ± 1,13 mL/cmH2O e 1,82 ± 0,77 mL/cmH2O, respectivamente) do que no controle (3,67 ± 1,38 mL/cmH2O). A proporção de neutrófilos e a atividade das metaloproteinases 2 e 9 em lavado broncoalveolar foram significantemente maiores nos grupos AO e EFC/AO que no controle. O acometimento pulmonar avaliado por morfometria foi significantemente maior nos grupos AO e EFC/AO (72,9 ± 13,8% e 77,6 ± 18,0%, respectivamente) do que nos grupos controle e EFC (8,7 ± 4,1% e 32,7 ± 13,1%, respectivamente), e esse acometimento foi significantemente maior no grupo EFC que no grupo controle. CONCLUSÕES: A administração endovenosa de EFC, nas doses e tempos deste estudo, associou-se à LPA mínima. O EFC não potencializou a LPA induzida por AO. Estudos adicionais são necessários para esclarecer o papel potencial desse modelo como método de estudo dos mecanismos de agressão pulmonar pelo tabaco.

OBJECTIVE: To investigate the acute effects of intravenous administration of cigarette smoke extract (CSE) on histological, inflammatory, and respiratory function parameters in rats, as well as to compare this potential acute lung injury (ALI) model with that with the use of oleic acid (OA). METHODS: We studied 72 Wistar rats, divided into four groups: control (those injected intravenously with saline); CSE (those injected intravenously with CSE and saline); OA (those injected intravenously with saline and OA); and CSE/OA (those injected intravenously with CSE and OA). RESULTS: Mean lung compliance was significantly lower in the OA and CSE/OA groups (2.12 ± 1.13 mL/cmH2O and 1.82 ± 0.77 mL/cmH2O, respectively) than in the control group (3.67 ± 1.38 mL/cmH2O). In bronchoalveolar lavage fluid, the proportion of neutrophils was significantly higher in the OA and CSE/OA groups than in the control group, as was the activity of metalloproteinases 2 and 9. Pulmonary involvement, as assessed by morphometry, was significantly more severe in the OA and CSE/OA groups (72.9 ± 13.8% and 77.6 ± 18.0%, respectively) than in the control and CSE groups (8.7 ± 4.1% and 32.7 ± 13.1%, respectively), and that involvement was significantly more severe in the CSE group than in the control group. CONCLUSIONS: The intravenous administration of CSE, at the doses and timing employed in this study, was associated with minimal ALI. The use of CSE did not potentiate OA-induced ALI. Additional studies are needed in order to clarify the potential role of this model as a method for studying the mechanisms of smoking-induced lung injury.

Oleic acid induces lung injury in mice through activation of the ERK pathway.

Oleic acid (OA) can induce acute lung injury in experimental models. In the present work, we used intratracheal OA injection to show augmented oedema formation, cell migration and activation, lipid mediator, and cytokine productions in the bronchoalveolar fluids of Swiss Webster mice. We also demonstrated that OA-induced pulmonary injury is dependent on ERK1/2 activation, since U0126, an inhibitor of ERK1/2 phosphorylation, blocked neutrophil migration, oedema, and lipid body formation as well as IL-6, but not IL-1ß production. Using a mice strain carrying a null mutation for the TLR4 receptor, we proved that increased inflammatory parameters after OA challenges were not due to the activation of the TLR4 receptor. With OA being a Na/K-ATPase inhibitor, we suggest the possible involvement of this enzyme as an OA target triggering lung inflammation.

Mechanisms involved in Jurkat cell death induced by oleic and linoleic acids.

BACKGROUND & AIMS: Previous study from our laboratory showed the toxicity of oleic (OA) and linoleic acids (LA) on Jurkat and Raji cells and human lymphocytes in vitro. The mechanisms involved in the toxicity induced by OA and LA on Jurkat cells were determined in vitro. METHODS: Jurkat cells were treated in the presence of OA and LA (25, 50, 100 and 200muM). The parameters investigated were: triglycerides and cholesterol ester concentrations determined by enzymatic assay, activation of peroxisome proliferator activated receptor (PPAR) by electrophoretic mobility shift assay, caspase 3, 6 and 8 activities by spectrofluorometric assay, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma production by enzyme linked absorbent assay (ELISA), expression of pro- (Bax) and anti- (Bcl-2) apoptotic genes by real time polymerase chain reaction and expression of pleiotropic genes by macroarray technique RESULTS: Evidence is presented herein that the increase in triglycerides concentrations induced by OA is more pronounced than that caused by LA in Jurkat cells. Importantly, triglycerides accumulation may be a mechanism to protect lymphocytes against the toxicity induced by fatty acids. Both fatty acids raised PPAR activation, caspase 3 and 6 activities and TNF-alpha production. LA in toxic concentrations modulated the expression of genes related to cell cycle, apoptosis, proliferation, oxidative stress, and cytokine receptors. CONCLUSION: The findings reported herein support the cell death induced by OA and LA involved triglycerides accumulation, PPAR activation, caspase 3 and 6 activities and TNF-alpha production.

Fatty acid-induced toxicity and neutral lipid accumulation in insulin-producing RINm5F cells.

Fatty acids have been shown to cause death of rat and human primary pancreatic beta cells and of insulin-producing cell lines. These studies focused mainly on saturated and monounsaturated FA such as palmitic, stearic and oleic acids. In this study, we have performed a comparison of the toxicity of a wider range of FA. The toxicity of different FA to insulin-producing RINm5F cells was assessed by flow cytometry measuring loss of plasma membrane integrity and increase in DNA fragmentation. Additionally, the FA induced neutral lipid accumulation and the FA composition were determined. Palmitic, linoleic, gamma-linolenic, oleic, stearic, and eicosapentaenoic acid caused DNA fragmentation of insulin-producing RINm5F cells. Loss of membrane integrity was mainly caused by linoleic and gamma-linolenic acid. There was no correlation between cytotoxicity and the abundance of the FA in the cells as determined by HPLC analysis. Taken as whole, the toxic effect of the FA on insulin-producing RINm5F cells varied irrespective of the chain length and the degree of unsaturation. In these cells PA and LA exhibited the highest toxicity, whereas AA was not toxic. In addition, the toxicity of most tested FA was inversely related to low NLA, except for AA and EPA. The results of this study contribute to the understanding of the role of FA in the impairment of pancreatic beta cell function that occurs in type 2 diabetes and obesity.

Comparative toxicity of oleic and linoleic acid on human lymphocytes.

Commercially available lipid emulsions for parenteral nutrition are mainly composed by long chain triacylglycerol containing a high proportion of linoleic acid (LA) or oleic acid (OA). The immunological impact of such therapy is particularly important because parenteral diets are often administered to critically ill patients as a mechanism to supply adequate nutrition during catabolic stress conditions. The comparative toxicity of OA and LA on human lymphocytes and the type of cell death induced by these fatty acids were determined in vitro. Parameters of cell death were investigated by flow cytometry-cell viability, DNA fragmentation, phosphatidylserine externalization, mitochondrial depolarization, neutral lipid accumulation and production of reactive oxygen species-and by fluorescence microscopy-chromatin condensation. Additionally a spectrofluorometric assay was employed to determine the activities of caspase--3, 6 and 8. Evidence is presented herein that OA is less toxic to human lymphocytes than LA. However, both fatty acids promoted apoptosis and necrosis of these cells. The mechanism of cell death induced by OA involved activation of caspase 3 while the mechanism of death induced by LA involved mitochondrial depolarization and ROS production. Importantly, neutral lipid accumulation may be a mechanism to protect lymphocytes against the toxicity induced by OA. OA may offer an immunological less problematic alternative to LA with respect to fatty acid composition of parenteral nutritional emulsions.

Comparative toxicity of oleic acid and linoleic acid on Raji cells.

OBJECTIVE: Parenteral diets are often administered to critically ill patients. To study one of the effects of commercially available parenteral lipid diets, rich in triacylglycerol esters of omega-6 polyunsaturated fatty acids or omega-9 monounsaturated fatty acids, on the immune system of such patients, we evaluated the cytotoxicity of oleic and linoleic acids on Raji cells that had been derived from human B-lymphocytes. METHODS: Cell death intensity and type were investigated by flow cytometry by quantitation of cell volume, granularity, DNA fragmentation, mitochondrial depolarization, and lipid accumulation. Fluorescence microscopy was used to determine chromatin condensation and type of cell death (acridine orange/ethidium bromide assay). Gene expression of BCL-XL, BCL-XS, C-MYC, and P53 was studied by reverse transcriptase polymerase chain reaction. RESULTS: Oleic acid was less toxic than linoleic acid to Raji cells. Both fatty acids promote apoptosis and necrosis of these cells. The mechanism of cell death induced by these fatty acids seemed to involve mitochondrial depolarization, lipid accumulation, and overexpression of C-MYC and P53. CONCLUSION: Oleic acid may offer a less harmful alternative to linoleic acid in parenteral diets with respect to patient B-lymphocyte-mediated immunologic activity.

Comparative toxicity of oleic acid and linoleic acid on Jurkat cells.

BACKGROUND: Lipid emulsions for parenteral nutrition commercially available are mainly composed of long-chain triacylglycerol containing a high proportion of alpha-6 polyunsaturated fatty acids or alpha-9 monounsaturated fatty acids. The immunological impact of such therapy is particularly important because parenteral and enteral diets are often administered to critical ill patients. The comparative toxicity of oleic acid and linoleic acid on Jurkat cells, a human T lymphocyte cell line, and the type of cell death induced by these fatty acids were determined. METHODS: Cell death was investigated by cytometry: decrease in cell volume, increase of granularity, DNA fragmentation, phosphatidylserine externalization, mitochondrial depolarization, lipid accumulation; by fluorescence microscopy: chromatin condensation and acridine orange/ethidium bromide assay; and by RT-PCR: mRNA expression of apoptotic genes. RESULTS: Evidence is presented herein that oleic acid is much less toxic to Jurkat cells than linoleic acid. Both fatty acids promote apoptosis and necrosis of these cells. The mechanism of cell death induced by these fatty acids seem to involve with mitochondrial depolarization, lipid accumulation and the levels of C-MYC and P53 mRNA expression. CONCLUSION: Therefore, oleic acid may offer an immunological less harmful alternative to linoleic acid for parenteral and enteral diets preparation.

Effect of arachidonic acid on proliferation, cytokines production and pleiotropic genes expression in Jurkat cells--a comparison with oleic acid.

The effects of arachidonic (AA) and oleic acids (OA) on proliferation, cytokine production and pleiotropic genes expression in Jurkat T cells were investigated. The following parameters were evaluated: cytotoxicity assessed by loss of membrane integrity and DNA fragmentation, cell proliferation as measured by [14C]-thymidine incorporation, production of IL-2, IL-4, IL-10, and INF-gamma, and expression of pleiotropic genes as determined by macroarray technique (83 genes in total). AA was more toxic for Jurkat cells than OA. However, the inhibiting effect of OA on Jurkat cells proliferation was more pronounced than that of AA. The reduction in the production of IL-2 and INF-gamma was more intense by OA (50 microM) than by AA (5 microM). The percentage of genes changed by the fatty acids was: 20.5% (17 genes) for AA (5 microM) and only 2.4% (2 genes) for OA (50 microM). AA markedly affected the expression of genes clustered as: signal transduction pathways, transcription factors and related genes, cell cycle, defense and repair, apoptosis, DNA synthesis, cell adhesion, cytoskeleton and related genes. In particular, AA induced marked changes in cell cycle, signal transduction, and anti-apoptosis genes expression. Therefore, the effect of AA on T-lymphocyte function does involve regulation of expression of important genes, whereas oleic acid did not markedly affect gene expression of Jurkat cells.

Effects of mannitol on the acute lung injury induced by oleic acid in rats.

Our purpose was to evaluate the pulmonary effects of mannitol infusion in a rat model of acute lung injury induced by oleic acid (OA) to compare the effects of mannitol to those of another diuretic, furosemide (FUR), and to assess if mannitol effects remained after correction of the volume depletion induced by this agent. Acute lung injury was induced in Wistar rats by intravenous administration of 100 mg/kg of OA. Mannitol (1 mL of a 20% solution) was infused either 15 min before or 2 h after OA infusion. FUR was infused intravenously in a dose (1 mg/kg) that induced a similar amount of diuresis compared to mannitol. We also studied rats that received NaCl 0.9% infusion to correct for volume losses induced by mannitol. The severity of the acute lung injury was evaluated by morphometric studies of the lungs 4 h after OA infusion. The amount of intraalveolar fluid accumulation and the intensity of alveolar distention and collapse were evaluated. Mannitol infusion either 15 min before or 2 h after OA administration resulted in a significant decrease in the amount of intraalveolar edema and alveolar distention and collapse (P < 0.001). FUR administration before OA infusion had an effect similar to mannitol. We did not observe any significant effect of mannitol when the rats received saline infusion to correct for diuresis induced by mannitol. We conclude that mannitol decreases the severity of pulmonary injury induced by OA in rats. This effect is mainly due to its diuretic properties.