Comparative effects between electronic cigarette and tobacco cigarette smoke on oxidative markers in cultured immune cells isolated from rats

BACKGROUND

Tobacco cigarette smoke (TCS) was previously demonstrated to affect the innate and adaptive immune responses as a consequence of oxidant generation which play a pivotal role in neutrophilic airway inflammation. Aim of this paper was to investigate whether electronic cigarette smoke (ECS) generates reactive oxygen species (ROS) similarly to cigarette smoke.

METHOD

By means of a house made apparatus, ECS and TCS were collected in fetal bovine serum (FBS) which was used to grow immune cells isolated from rats. As index of oxidative products nitrite, superoxide, and thiobarbituric acid-reactive substances (TBARS) were determined in the medium before and after cell growth.

RESULTS

The results showed that: i) ECS caused a remarkable increase of nitrites and TBARS although in lesser extension than TCS; ii) the spleen and lymph node cells grown in ECS and TCS-exposed medium were able to reduce TBARS but not nitrites present in the medium; iii) PBMC in TCS-exposed medium were able to reduce nitrites and TBARS more efficiently than spleen and lymph node cells, but released more superoxide anion; iv) TCS and ECS not influence the PBMC and spleen T cell subtype populations (CD4+, CD8+).

CONCLUSIONS

As ECS nicotine-free gave the same results of unexposed medium, we can support the hypothesis that the increase of ROS in ECS exposed medium was prevalently due to nicotine.

The adenosine A2A receptor agonist T1-11 ameliorates neurovisceral symptoms and extends the lifespan of a mouse model of Niemann-Pick type C disease

Niemann-Pick C is a fatal neurovisceral disorder caused, in 95% of cases, by mutation of NPC1 gene. Therapeutic options are extremely limited and new "druggable" targets are highly warranted. We previously demonstrated that the stimulation of the adenosine A_2A receptor (A_2AR) normalized the pathological phenotype of cellular models of NPC1. Since the validation of A_2ARs as a therapeutic target for NPC1 can be obtained only conducting studies in in vivo models of the disease, in the present paper, the effects of two agonists of A_2ARs were evaluated in the mouse model Balb/c Npc1^nih, hereafter indicated as NPC1-/-. The agonists CGS21680 (2.5 and 5mg/kg/day by intraperitoneal injection) and T1-11 (50mg/kg/day in drinking water) were administered at a presymptomatic stage of the disease of NPC1-/- mice (PN28 and PN30, respectively); the experimental groups were the following: vehicle-treated WT mice (N=16 for both CGS and T1-11 treatments); vehicle-treated NPC1-/- mice (N=14 for CGS and 12 for T1-11 treatment); CGS-treated NPC1-/- mice (N=7) and T1-11-treated NPC1-/- mice (N=11). The efficacy of the treatments was evaluated by comparing vehicle-treated and CGS or T1-11-treated NPC1-/- mice for their motor deficits (analyzed by both rotarod and footprint tests), hippocampal cognitive impairment (by Novel Object Recognition (NOR) test), cerebellar neurodegeneration (Purkinje neurons counting), and cholesterol and sphingomyelin accumulation in spleen and liver. Finally, the effect of both agonists on survival was evaluated by applying a humane late endpoint (weight loss >30% of peak weight, punched posture and reduced activity in the cage). The results demonstrated that, while CGS21680 only slightly attenuated cognitive deficits, T1-11 ameliorated motor coordination, significantly improved cognitive impairments, increased the survival of Purkinje neurons and reduced sphingomyelin accumulation in the liver. More importantly, it significantly prolonged the lifespan of NPC1-/- mice. In vitro experiments conducted in a neuronal model of NPC1 demonstrated that the ability of T1-11 to normalize cell phenotype was mediated by the selective activation of A_2ARs and modulation of intracellular calcium levels. In conclusion, our results fully confirm the validity of A_2ARs as a new target for NPC1 treatment. As soon as new ligands with improved pharmacokinetic characteristics (i.e. orally active, with brain bioavailability and metabolic stability) will be obtained, A_2AR agonists could represent a breakthrough in the treatment of NPC.

An Integrated Approach to Explore Composition and Dynamics of Cholesterol-rich Membrane Microdomains in Sexual Stages of Malaria Parasite

Membrane microdomains that include lipid rafts, are involved in key physiological and pathological processes and participate in the entry of endocellular pathogens. These assemblies, enriched in cholesterol and sphingolipids, form highly dynamic, liquid-ordered phases that can be separated from the bulk membranes thanks to their resistance to solubilization by nonionic detergents. To characterize complexity and dynamics of detergent-resistant membranes of sexual stages of the rodent malaria parasite Plasmodium berghei, here we propose an integrated study of raft components based on proteomics, lipid analysis and bioinformatics. This analysis revealed unexpected heterogeneity and unexplored pathways associated with these specialized assemblies. Protein-protein relationships and protein-lipid co-occurrence were described through multi-component networks. The proposed approach can be widely applied to virtually every cell type in different contexts and perturbations, under physiological and/or pathological conditions.

Micronutrient-enriched rapeseed oils improve the brain oxidant/antioxidant system in rats fed a high-fat diet

The main proposal of this study was to evaluate in vivo whether micronutrient-enriched rapeseed oils obtained using different crushing and refining procedures and characterized by different quantities and qualities of micronutrients (optimized oils) could have any beneficial effect on the antioxidant status of the brain. Sprague-Dawley rats were fed a high-fat diet for 4 weeks. The lipid source consisted of 20% optimized rapeseed oils with different quantities and qualities of micronutrients. The control group received traditional refined rapeseed oil. The experimental optimized oils decreased lipid peroxidation and increased endogenous antioxidant status in parallel with the enhancement of micronutrients. No alteration in acetylcholinesterase activity was induced by the high-fat diet in any experimental group. These results indicate that a regular intake of optimized rapeseed oils can prevent oxidative stress, providing evidence that optimized rapeseed oils could be a functional food with potentially important neuroprotective properties.

Sexual dimorphic evolution of metabolic programming in non-genetic non-alimentary mild metabolic syndrome model in mice depends on feed-back mechanisms integrity for pro-opiomelanocortin-derived endogenous substances

Previously, we showed that our post-natal handling model induces pro-opiomelanocortin-derived (POMC) endogenous systems alterations in male mice at weaning. These alterations last up to adult age, and are at the basis of adult hormonal and metabolic conditions similar to mild metabolic syndrome/type-2 diabetes. Here, we evaluate how sex influences post-natal programming in these metabolic conditions. Subjects are adult control (non-handled) female (NHF) and male (NHM) CD-1 mice; adult post-natal handled female (HF) and male (HM) mice. Handling consists of daily maternal separation (10 min) plus sham injection, from birth to weaning (21 days). In adult handled males (90-days old) we find not only POMC-derived hormones alterations (enhanced basal plasma corticosterone (+91%) and ACTH (+109%)) but also overweight (+5.4%), fasting hyperglycemia (+40%), hypertriglyceridemia (+21%), enhanced brain mRNA expression of hydroxysteroid(11-beta)dehydrogenase type-1 (HSD11B1) (+49%), and decreased mRNA-HSD11B2 (-39%). Conversely, uric acid, creatinine, HDL(C), total cholesterol, glucose and insulin incremental area under-the-curve are not affected. In females, post-natal handling does not produce both hormonal and dysmetabolic diabetes-like changes; but handling enhances n3- and n6-poly-unsaturated, and decreases saturated fatty acids content in erythrocyte membrane composition in HF versus NHF. In conclusion, for the first time we show that female sex in mice exerts effective protection against the hypothalamus-pituitary-adrenal homeostasis disruption induced by our post-natal handling model on POMC cleavage products; endocrine disruption is in turn responsible for altered metabolic programming in male mice. The role of sex hormones is still to be elucidated.

Micronutrient-enriched rapeseed oils reduce cardiovascular disease risk factors in rats fed a high-fat diet

Many epidemiological studies have demonstrated that vegetable food consumption is associated with a reduced risk of cardiovascular diseases. The beneficial effects have been attributed to the content of bioactive molecules present in large quantities in plant food. The main proposal of this study was to evaluate in vivo whether micronutrient-enriched rapeseed oils (optimised oils) obtained using different crushing and refining procedures and characterised by different quantities and qualities of micronutrients, could have any beneficial effect on lipid profile and antioxidant status of plasma and liver. Sprague-Dawley rats were fed a high-fat diet for 4 weeks. The lipid source consisted of 20% optimised rapeseed oils with different quantities and qualities of micronutrients. The control group received traditional refined rapeseed oil. The experimental optimised oils all had a hypolipidaemic effect. In the group fed the highest levels of micronutrients, the reduction in plasma and hepatic triglycerides reached 25% and 17%, respectively, that of cholesterol 20% and 14%, respectively. In plasma, the ferric antioxidant capacity, superoxide dismutase, glutathione peroxidase and reduced glutathione significantly increased and lipid peroxidation decreased in parallel with the enhancement of micronutrients. The same trend was observed in the liver, except for glutathione peroxidase which was not affected by optimised oils. These results indicate that a regular intake of optimised rapeseed oils can help to improve lipid status and prevent oxidative stress, providing evidence that optimised oils could be a functional food with potentially important cardioprotective properties.

Effect of arachidonic, eicosapentaenoic and docosahexaenoic acids on the oxidative status of C6 glioma cells

n-3 polyunsaturated fatty acids (PUFAs) have been described to have beneficial effects on brain development and in the prevention and treatment of brain damage. C6 glioma cells were incubated with 100 microM of either C20:4n-6 (ARA), or C20:5n-3 (EPA), or C22:6n-3 (DHA) for different time periods to assess whether these acids altered the cellular oxidative state. The ARA and EPA were promptly metabolised to C22:4n-6 and C22:5n-3, respectively, whereas DHA treatment simply increased the amount of DHA in the cells. Cell viability was not affected by ARA, while a cytotoxic effect was observed 72 h after n-3 PUFAs supplementation. The levels of reactive oxygen species and thiobarbituric acid-reactive substances were significantly higher in DHA-treated cells than in EPA- and ARA-treated groups. This modification in the oxidative cellular status was also highlighted by a significant increase in catalase activity and a decrease in glutathione content in DHA-supplemented cells. Glucose-6-phosphate dehydrogenase activity, an enzyme involved in redox regulation, and O2*- release were significantly increased both in EPA and DHA groups. The effect of DHA was more severe than that of EPA. No significant changes were observed in the ARA group with respect to untreated cells. These data show that EPA and DHA induce alterations in the oxidative status that could affect the glial function.

Docosahexaenoic acid supplementation induces dose and time dependent oxidative changes in C6 glioma cells

In view of the promising use of n-3 polyunsaturated fatty acids (PUFAs) in the prevention and treatment of neurological diseases, it is necessary to ascertain the lack of detrimental oxidative effects. We evaluated short- and long-term effects of 25, 50 and 75 muM docosahexaenoic acid (DHA) supplementation on the oxidative status of C6 glial cells. DHA was incorporated into cells dose and time dependently without any cytotoxic effect. Reactive oxygen species (ROS) level was related to DHA dose and supplementation time. At the lowest dose no significant increase in ROS values was observed at hour 24. Low doses of DHA strengthened the cellular antioxidant defence system as highlighted by a raise in both GPX and catalase activity, and the decreased levels of lipid peroxidation. This effect was pronounced at 24 h of supplementation, almost disappeared at hour 48, while after 72 h an opposite effect was observed: lipid peroxidation increased concomitantly with DHA doses. Therefore, the final effect of DHA on cellular redox status is dependent on dose and time supplementation.

PMP70 knock-down generates oxidative stress and pro-inflammatory cytokine production in C6 glial cells

By using RNA interference (RNAi) in rat C6 glial cells, we previously generated the cell line abcd3kd in which the peroxisomal half-transporter PMP70 was stably knocked-down. The observations that abcd3kd cells had peroxisomal beta-oxidation impairment and an increase of hexacosenoic acid in cholesterol ester fraction, indicated an overlapping function of PMP70 with adrenoleukodystrophy protein (ALDP), the peroxisomal half-transporters involved in X-linked adrenoleukodystrophy (X-ALD). The objective of the present study was to investigate whether PMP70 could affect some oxidative and inflammatory parameters, since many findings indicate oxidative damage in the brain of ALD patients and inflammation is a hallmark of the cerebral forms of X-ALD. We thus measured parameters indicative of oxidative stress, the expression or activity of antioxidant enzymes, and the production of some pro-inflammatory cytokines. Our results show that, due to inducible nitric oxide synthase up-regulation, abcd3kd cell line produces higher levels of nitrites than native C6 cells. The enhanced production of superoxide and thiobarbituric acid-reactive substances, the increased expression of mitochondrial superoxide dismutase, and the reduction of catalase and glutathione peroxidase activities confirm the presence of an oxidative process. We then measured the concentrations of TNFalpha, IFNgamma, and IL-12 and we observed that abcd3kd cells produce higher amounts of pro-inflammatory cytokines compared to native C6 cells. By using neutralizing antibodies against IL-12, not only inflammatory parameters significantly decrease, but nitrite and superoxide production is also affected. This demonstrates that oxidative status of abcd3kd cells is not a direct PMP70 knock-down consequence, but depends on IL-12 release. The scenery induced by the knock-down of PMP70 in C6 cells recall the oxidative and inflammatory status observed in human X-ALD and thus reinforce the idea that PMP70 could affect the clinical course of the disease.

Eicosapentaenoic acid stimulates the expression of myelin proteins in rat brain

We have previously demonstrated that, in C6 glioma cells, eicosapentaenoic acid (EPA) stimulates the expression of proteolipid protein (PLP) via cAMP-mediated pathways. In this study, we investigated whether n-3 polyunsaturated fatty acids can affect myelinogenesis in vivo. A single dose of either EPA or docosahexaenoic acid (DHA) was injected intracerebroventricularly into 2-day-old rats, which were then killed after 3 days post-injection (p.i.). Total RNA was isolated from the medulla, cerebellum, and cortex, and the expression of myelin-specific mRNAs was analyzed by real-time PCR. The levels of PLP, myelin basic protein, and myelin oligodendrocyte protein mRNAs increased in nearly all brain regions of DHA- and EPA-treated animals, but the effect was more pronounced in EPA-treated rats. The enhancement in PLP transcript levels was followed by an increase in PLP translation in EPA-treated rats. A further indicator of accelerated myelination was the increase in 2'-3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) protein levels. In EPA-treated rats, the increased expression of myelin genes coincided with a decrease of cAMP-response element-binding protein (CREB)-DNA binding in the cerebellum and cortex (1 hr p.i.). After 16 hr, this effect was still present in the same cerebral regions even though the decrease in EPA-treated rats was less pronounced than in controls. The down-regulation of CREB activity was due to a decrease in the levels of CREB phosphorylation. In conclusion, our data suggest that EPA stimulates the expression of specific myelin proteins through decreased CREB phosphorylation. These results corroborate the clinical studies of the n-3 PUFA beneficial effects on several demyelinating diseases.

Effects of L-mono Methyl-arginine, N-Acetyl-cysteine and Diphenyleniodonium on Free Radical Release in C6 Glial Cells Enriched in Hexacosenoic Acid

Previously, we have shown that C6 glial cells enriched in hexacosenoic acid (HA) incubated with oxidative stressors released higher amounts of nitric oxide (NO) products and superoxide (O2(-)), compared to native C6 cells. In the present study, we examined the effects of pretreatment with some of free radical release inhibitors. The aim was to determine the origin of the enhanced generation of NO and superoxide, and to test the possibility of preventing it. Pre-treatment with L-mono-methyl-arginine and N-acetyl-cysteine in oxidized low-density lipoprotein (ox-LDL) exposed HA cells, inhibited not only nitrite but also superoxide production suggesting that O2(-) anion could partially derive from inducible NO synthase. We also observed that ox-LDL treatment of HA cells reduced the intracellular glutathione levels and activated extracellular signal-related kinases. Since this signalling is related to neurotoxic effect, our data substantiate the role of the free radicals in X-linked adrenoleukodystrophy pathogenesis, as HA cells have been used as an in vitro model for this disease.

Retracted : Identification of seven novel mutations in ABCD1 by a DHPLC‐based assay in Italian patients with X‐linked adrenoleukodystrophy

We report the molecular findings in 14 patients (12 families) with X-linked adrenoleukodystrophy (X-ALD, MIM# 300100), a well-defined peroxisomal disorder attributed to mutations in the ABCD1 gene on chromosome Xq28. With the aims of determining the spectrum of mutations and developing an efficient molecular genetic test for analysis of at-risk women whose carrier status is unknown, and to offer molecular confirmation of their status to obligate heterozygotes, regardless of their clinical status, we carried out molecular screening by setting up a denaturing high-performance liquid chromatography (DHPLC)-based protocol. We identified eleven hemizygous base changes in ABCD1, including seven new mutations (c.145underscore;146ins4, c.264C>G, c.919C>T, c.994C>T, c.1027G>A, c.1508T>C, and c.1540A>C, resulting in the p.Pro193fs, p.Cys88Trp, p.Gln307X, p.Gln332X, p.Gly343Ser, p.Leu503Pro, and p.Ser514Arg changes, respectively). Adding new variants to the repertoire of ABCD1 mutations in X-ALD, our data provide an efficient, cost-effective, and reliable DHPLC detection protocol for mutation screening of X-ALD families.

Free radical release in C6 glial cells enriched in hexacosanoic acid: implication for X-linked adrenoleukodystrophy pathogenesis

Free radicals have been implicated in the etiopathology of some neurological and demyelinating diseases. To evaluate their involvement in the cerebral form of X-linked adrenoleukodystrophy (cerALD) disorder, characterised by very long chain fatty acid (VLCFA) accumulation, we utilised an in vitro model using rat C6 glial cells, enriched in hexacosenoic acid (C26:0, HA). Modified cells were incubated in presence of oxidative stressors, such as bacterial endotoxin lipopolisaccharides (LPS) and human oxidised low-density lipoprotein (ox-LDL), and the production of proinflammatory cytokines, nitrite, nitrate and superoxide was determined in the supernatants. The results show that modified cells produce higher amounts of nitric oxide (NO) products and superoxide compared to native C6 cells, supporting the role of free radicals as important pathophysiological modulator of the neuroinflammatory response in ALD. This hypothesis suggests that the cerebral damage in ALD could be due to intracellular signalling activated by interaction of exogenous factors with the particular membrane fatty acid composition.

Stimulation of myelin proteolipid protein gene expression by eicosapentaenoic acid in C6 glioma cells

In this study, the role of exogenous fatty acids in the regulation of proteolipid protein (PLP) gene expression was investigated using the following model culture system: C6 glioma cells expressing the green-fluorescent protein (eGFP) driven by different segments of PLP promoter. Eicosapentanoic acid (EPA; 20:5 n-3), but not arachidonic acid (AA; 20:4 n-6), induced a significant increase in medium fluorescence intensity (MFI) determined by fluorescence-activated cell sorting (FACS). The induction of PLP promoter was time-dependent showing maximal activity between 24 and 48 h after EPA exposure. PLP promoter activation was dependent on fatty acid concentration, with maximum activation at 200 microM. Northern blot analysis confirmed the fluorescence data in C6 cells incubated with EPA. Furthermore, this treatment increased the adenylyl cyclase-cyclic AMP (cAMP) levels and the mitogen-activated protein kinase (MAPK) activation in C6 cells. PLP promoter activity was inhibited by pre-treatment with H89 (protein kinase A (PKA) inhibitor), but not with PD98059 (MAPK inhibitor), suggesting that EPA stimulates the expression of PLP via cAMP-mediated pathways.

Dietary prenatal lipids affect myelin gene expression in postnatal undernourished rats

The effects on myelin gene expression of prenatal diets with a different lipid content and fatty acid composition were investigated in undernourished pups. Three groups of rats were fed ad libitum during gestation diets containing either 10% of margarine or 10% of microbial lipids or a standard diet containing 3.5% of lipids. After birth, all groups were switched to a reduced intake (60%) of the standard diet. A control group received ad libitum, the standard diet during pregnancy and throughout lactation. At birth no difference in body and brain weight was observed among the groups and the only significant difference in the brain fatty acid composition was the presence of odd-chain fatty acids in the group fed microbial lipids. Milk was removed from the stomach of pups at 1, 5 and 9 days of lactation for fatty acid analysis. During undernourishment, the monoenoic fatty acid and polyenoic fatty acid percentage was always higher and lower, respectively, in the groups fed 10% than in the group fed 3.5% of lipids during pregnancy. The expression of myelin genes at 11 days of undernutrition was determined in different brain regions by Northern analysis. In the standard group, the proteolipid protein and myelin oligodendrocyte glycoprotein transcripts were well detected only in the medulla whereas in groups fed 10% of lipids the transcripts were also visible in the cerebellum. These data suggest that the high lipid content of the prenatal diet independently from its fatty acid composition affects the myelin gene expression decreasing myelin susceptibility to postnatal undernutrition.