A study to estimate and correlate cigarette smoke exposure in smokers in Germany as determined by filter analysis and biomarkers of exposure

A clinical study, conducted in Germany, compared two methods of estimating exposure to cigarette smoke. Estimates of mouth level exposure (MLE) to nicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), pyrene and acrolein were obtained by chemical analysis of spent cigarette filters for nicotine content. Estimates of smoke constituent uptake were achieved by analysis of corresponding urinary biomarkers: for nicotine; total nicotine equivalents (nicotine, cotinine, trans-3'-hydroxycotinine plus their glucuronide conjugates), for NNK; (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) plus glucuronide, for pyrene; 1-hydroxy pyrene (1-OHP) plus glucuronide and for acrolein; 3-hydroxylpropyl-mercapturic acid (3-HPMA) plus the nicotine metabolite cotinine in plasma and saliva. Two hundred healthy volunteer subjects were recruited; 50 smokers of each of 1-2 mg, 4-6 mg and 9-10 mg ISO tar yield cigarettes and 50 non-smokers (NS). Smokers underwent two periods of home smoking, each followed by residence in a clinic. Smoking was permitted ad libitum, and spent cigarette filters, cigarette consumption data, 24h urine, as well as plasma and saliva samples were collected. Significant correlations (p<0.001) were found between MLE and the relevant biomarker for each smoke constituent. The Pearson correlation coefficients (r) were 0.83 (nicotine), 0.76 (NNK), 0.82 (acrolein) and 0.63 (pyrene). Mean MLE estimates for nicotine, NNK and pyrene showed a dose response in line with ISO tar yield smoked, with 10 mg > 4 mg >1 mg, and for acrolein 10 mg> 4 mg > *1mg (where * indicates not significant at 95% confidence level). The mean exposure estimates from biomarkers for nicotine, NNK and acrolein also showed a dose response in line with ISO tar yield with 10 mg > 4 mg > 1 mg > NS, and for pyrene 10 mg > *4 mg> 1 mg> NS. This study shows that estimates of exposure obtained by filter analysis and biomarkers of exposure correlate significantly over a wide range of smoke exposures and that filter analysis may provide a simple and effective alternative to biomarkers for estimating smokers' exposure.

Tissue distribution of lipid peroxidation product acrolein in human colon carcinogenesis

Lipid peroxidation product acrolein, well-known pollutant in tobacco and automotive smoke, accumulates in vivo bound to proteins. It suppresses p53 synthesis acting as potent carcinogenic factor for oral, respiratory and bladder carcinomas, while its possible association with colon carcinogenesis was not studied so far. We used genuine monoclonal antibody to evaluate immunohistochemical distribution of acrolein-protein adducts in 113 human colon tumours. The presence of acrolein-protein adducts was increasing with respect to colon carcinogenesis, from moderate appearance in tubular and villotubular low-grade adenomas to abundant and diffuse distribution in high-grade villotubular adenomas and Dukes A carcinomas. However, in advanced Dukes B and C carcinomas acrolein was hardly noticed, although, its protein adducts were found abundant in non-malignant colon epithelium of these patients. There was no relationship between p53 and acrolein distribution. According to these findings, acrolein seems to be lipid peroxidation product associated with transition from benign into malignant colon tumours.

Acrolein, a ubiquitous pollutant and lipid hydroperoxide product, inhibits antiviral activity of interferon-alpha: relevance to hepatitis C

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease and can lead to hepatocellular carcinoma and end-stage liver disease. The current FDA-approved treatment for HCV (pegylated interferon-alpha (IFNalpha) with ribavirin) is effective in only about 50% of patients. Epidemiological evidence suggests that obesity, alcohol, smoking, and environmental pollutants may contribute to resistance to IFNalpha therapy in HCV. Acrolein, a ubiquitous environmental pollutant and major component of cigarette smoke, is also generated endogenously by cellular metabolism and lipid peroxidation. This study examines the effects of acrolein on (i) IFNalpha-mediated signaling and antiviral gene expression in cultured and primary human hepatocytes and (ii) HCV replication in an HCV-replicon system. Our data demonstrate that nontoxic concentrations of acrolein significantly inhibited IFNalpha-induced tyrosine phosphorylation of both cytoplasmic and nuclear STAT1 and STAT2, without altering the total levels. Also, acrolein down-regulated IFNalpha-stimulated gene transcription, resulting in reduced expression of antiviral genes. Importantly, acrolein abolished the IFNalpha-mediated down-regulation of HCV viral expression in the HCV-replicon system. This study defines mechanisms involved in resistance to IFNalpha and identifies the pathogenic role of acrolein, and potentially other environmental pollutants, in suppressing IFNalpha antiviral activity and establishes their adverse impact on HCV therapy.

Glutathione-S-transferase P protects against endothelial dysfunction induced by exposure to tobacco smoke

Exposure to tobacco smoke impairs endothelium-dependent arterial dilation. Reactive constituents of cigarette smoke are metabolized and detoxified by glutathione-S-transferases (GSTs). Although polymorphisms in GST genes are associated with the risk of cancer in smokers, the role of these enzymes in regulating the cardiovascular effects of smoking has not been studied. The P isoform of GST (GSTP), which catalyzes the conjugation of electrophilic molecules in cigarette smoke such as acrolein, was expressed in high abundance in the mouse lung and aorta. Exposure to tobacco smoke for 3 days (5 h/day) decreased total plasma protein. These changes were exaggerated in GSTP(-/-) mice. Aortic rings isolated from tobacco smoke-exposed GSTP(-/-) mice showed greater attenuation of ACh-evoked relaxation than those from GSTP(+/+) mice. The lung, plasma, and aorta of mice exposed to tobacco smoke or acrolein (for 5 h) accumulated more acrolein-adducted proteins than those tissues of mice exposed to air, indicating that exposure to tobacco smoke results in the systemic delivery of acrolein. Relative to GSTP(+/+) mice, modification of some proteins by acrolein was increased in the aorta of GSTP(-/-) mice. Aortic rings prepared from GSTP(-/-) mice that inhaled acrolein (1 ppm, 5 h/day for 3 days) or those exposed to acrolein in an organ bath showed diminished ACh-induced arterial relaxation more strongly than GSTP(+/+) mice. Acrolein-induced endothelial dysfunction was prevented by pretreatment of the aorta with N-acetylcysteine. These results indicate that GSTP protects against the endothelial dysfunction induced by tobacco smoke exposure and that this protection may be related to the detoxification of acrolein or other related cigarette smoke constituents.

Antioxidants and phase 2 enzymes in macrophages: regulation by Nrf2 signaling and protection against oxidative and electrophilic stress

Macrophages play important roles in immunity and other physiological processes. They are also target cells of various toxic agents, including oxidants and electrophiles. However, little is known regarding the molecular regulation and chemical inducibility of a spectrum of endogenous antioxidants and phase 2 enzymes in normal macrophages. Understanding the molecular pathway(s) controlling the coordinated expression of various macrophage antioxidants and phase 2 defenses is of importance for developing strategies to protect against macrophage injury induced by oxidants and electrophiles. Accordingly, this study was undertaken to determine the role of the nuclear factor E2-related factor 2 (Nrf2) in regulating both constitutive and chemoprotectant-inducible expression of various antioxidants and phase 2 enzymes in mouse macrophages. The constitutive expression of a series of antioxidants and phase 2 enzymes was significantly lower in macrophages derived from Nrf2-null (Nrf2(-/-)) mice than those from wild-type (Nrf2(+/+)) littermates. Incubation of wild-type macrophages with 3H-1,2-dithiole-3-thione (D3T) led to significant induction of various antioxidants and phase 2 enzymes, including catalase, glutathione, glutathione peroxidase (GPx), glutathione reductase, glutathione S-transferase, and NAD(P)H:quinone oxidoreductase 1. The inducibility of the above cellular defenses except for GPx by D3T was completely abolished in Nrf2(-/-) macrophages. As compared with wild-type cells, Nrf2(- /-) macrophages were much more susceptible to cell injury induced by reactive oxygen/nitrogen species, as well as two known macrophage toxins, acrolein and cadmium. Up-regulation of the antioxidants and phase 2 enzymes by D3T in wild-type macrophages resulted in increased resistance to the above oxidant-and electrophile-induced cell injury, whereas D3T treatment of Nrf2(- /-) macrophages provided only marginal or no cytoprotec-tion. This study demonstrates that Nrf2 is an indispensable factor in controlling both constitutive and inducible expression of a wide spectrum of antioxidants and phase 2 enzymes in macrophages as well as the susceptibility of these cells to oxidative and electrophilic stress.

Oxidative stress as a biomarker of respiratory disturbance in patients with severe motor and intellectual disabilities

Oxidative stress plays an important role in aging and various diseases such as cancer, cardiovascular diseases, diabetes mellitus and bronchial asthma. However, little is known about a potential role of oxidative stress in the pathogenesis of severe motor and intellectual disabilities (SMID) in terms of respiratory disturbance, which is the most common complication. In the present study, we examined the urinary levels of oxidative stress markers, 8-hydroxy-2'-deoxyguanosine (8-OHdG), hexanoyl-lysine adduct (HEL) and acrolein-lysine adduct (ACR) in patients with SMID. The mean level of urinary 8-OHdG in SMID patients was significantly higher than that in normal controls (18.8 +/- 9.0 ng/mg Cre and 10.5 +/- 2.9 ng/mg Cre, respectively) (p < 0.01). There was no significant difference of the mean level of urinary HEL between patients with SMID and normal controls (81.9 +/- 40.3 pmol/mg Cre and 69.2 + /-37.7 pmol/mg Cre, respectively), while the mean level of ACR in patients with SMID was higher than that of normal controls (220.5 +/- 118.6 nmol/mg Cre and 144.9 +/- 62.0 nmol/mg Cre, respectively) (p < 0.05). In addition, the level of 8-OHdG was strongly correlated with the severity of respiratory disturbance evaluated as the respiratory disturbance score (RDS) (Spearman r = 0.73, n = 14, p < 0.01). In contrast, there was no correlation between the levels of these oxidative stress markers and age or medication of antiepileptic drugs. These results suggest that urinary 8-OHdG is a potentially useful biomarker for evaluating the severity of respiratory failure in patients with SMID.

Acrolein: sources, metabolism, and biomolecular interactions relevant to human health and disease

Acrolein (2-propenal) is ubiquitously present in (cooked) foods and in the environment. It is formed from carbohydrates, vegetable oils and animal fats, amino acids during heating of foods, and by combustion of petroleum fuels and biodiesel. Chemical reactions responsible for release of acrolein include heat-induced dehydration of glycerol, retro-aldol cleavage of dehydrated carbohydrates, lipid peroxidation of polyunsaturated fatty acids, and Strecker degradation of methionine and threonine. Smoking of tobacco products equals or exceeds the total human exposure to acrolein from all other sources. The main endogenous sources of acrolein are myeloperoxidase-mediated degradation of threonine and amine oxidase-mediated degradation of spermine and spermidine, which may constitute a significant source of acrolein in situations of oxidative stress and inflammation. Acrolein is metabolized by conjugation with glutathione and excreted in the urine as mercapturic acid metabolites. Acrolein forms Michael adducts with ascorbic acid in vitro, but the biological relevance of this reaction is not clear. The biological effects of acrolein are a consequence of its reactivity towards biological nucleophiles such as guanine in DNA and cysteine, lysine, histidine, and arginine residues in critical regions of nuclear factors, proteases, and other proteins. Acrolein adduction disrupts the function of these biomacromolecules which may result in mutations, altered gene transcription, and modulation of apoptosis.

Intermolecular protein cross-linking during acrolein toxicity: efficacy of carbonyl scavengers as inhibitors of heat shock protein-90 cross-linking in A549 cells

The smoke-borne electrophile acrolein reacts extensively with proteins, forming carbonyl-retaining Michael adducts that may be attacked by adjacent protein nucleophiles to form cross-links. Because little information is available concerning the extent of intermolecular protein cross-linking during acrolein toxicity in cells, we used an antibody against a known target for toxic carbonyls, the chaperone protein Hsp90, to detect the formation of high-mass protein complexes in acrolein-exposed A549 cells. A 3 h exposure to acrolein (0 to 200 microM) resulted in concentration-dependent formation of a single high-mass band (approx. 180 kDa). This species was detected in cells exposed to just 50 microM acrolein, a concentration that did not elicit acute cell death as assessed by measurements of cell ATP levels. The formation of cross-linked Hsp90 coincided with a rapid loss of carbonyl adducts within cells that had been subjected to a brief "pulse" exposure to a subtoxic concentration of acrolein, suggesting Michael adducts are short-lived within cells due in part to consumption during reactions with protein nucleophiles. Cross-linked Hsp90 persisted following an overnight recovery incubation, suggesting the cellular ability to repair or degrade these species is limited. Two known carbonyl scavengers, hydralazine and bisulfite, strongly protected against the ATP depletion accompanying acrolein exposure, but only the latter suppressed protein adduction and Hsp90 cross-linking. As previously shown for hydralazine, mass spectrometry studies using a model peptide indicated that bisulfite traps carbonyl groups possessed by Michael addition adducts, and such adduct-trapping reactivity appeared to contribute to the blockade of Hsp90 cross-linking in acrolein-preloaded cells. Collectively, these findings establish that formation of stable intermolecular protein cross-links accompanies exposure to acrolein. Future clarification of the chemistry underlying this damage may provide novel biomarkers of acrolein exposure.

An Experimental Test of the Immunocompetence Handicap Hypothesis in a Teleost Fish: 11‐Ketotestosterone Suppresses Innate Immunity in Three‐Spined Sticklebacks

The immunocompetence handicap hypothesis (ICHH) provides a functional explanation for how sexual ornaments can provide honest signals of male quality. A key aspect of this hypothesis is that testosterone (T) has a bimodal effect: a higher T level enhances the expression of ornaments (increasing mating success and, ultimately, fitness); however, at the same time, it suppresses immune function. Tests of the latter assumption, which have focused mainly on aspects of adaptive immunity in birds, led to equivocal results. We performed a hormone-implant experiment in male three-spined sticklebacks (Gasterosteus aculeatus) to test the key assumptions of the ICHH in a fish, where the dominant circulating androgen is 11-ketotestosterone (11kT) rather than T. Males were implanted with 11-ketoandrostenedione, which is a natural precursor of 11kT. Each individual's circulating 11kT level, ornamentation, and immunocompetence were measured 2 weeks later. In addition, we quantified oxidative tissue damage because the ICHH has been hypothesized to work via oxidative stress. We found that the males' 11kT levels correlated positively with ornamentation but negatively with immunocompetence, in particular, measures of innate immunity. Moreover, there was a trend for fish with high 11kT levels to suffer more from oxidative stress. Thus, our data provide support for the ICHH.

Oxidative damage in age-related macular degeneration

Epidemiologic studies have suggested that elderly patients who consumed diets rich in antioxidants throughout their lives are less likely to be afflicted with age-related macular degeneration (AMD). This led to the Age-Related Eye Disease Study, which showed that supplements containing antioxidant vitamins and zinc reduce the risk of progression to severe stages of AMD. Despite these data that indirectly implicate oxidative damage in the pathogenesis of AMD, there has not been any direct demonstration of increased oxidative damage in the retinas of patients with AMD. In this study, we used biomarkers of oxidative damage in postmortem eyes from patients with AMD and comparably aged patients without AMD to directly assess for oxidative damage. Sections from 4 eyes with no pathologic features of AMD showed no immunofluorescent staining for markers of oxidative damage, while sections from 8 of 12 eyes with advanced geographic atrophy showed evidence of widespread oxidative damage in both posterior and anterior retina. Only 2 of 8 eyes with choroidal neovascularization and 2 of 16 eyes with diffuse drusen and no other signs of AMD showed evidence of oxidative damage. These data suggest that widespread oxidative damage occurs in the retina of some patients with AMD and is more likely to be seen in patients with advanced geographic atrophy. This does not rule out oxidative damage as a pathogenic mechanism in patients with CNV, but suggests that a subpopulation of patients with geographic atrophy may have a major deficiency in the oxidative defense system that puts the majority of cells in the retina at risk for oxidative damage.

Formation of an adduct between insulin and the toxic lipoperoxidation product acrolein decreases both the hypoglycemic effect of the hormone in rat and glucose uptake in 3T3 adipocytes

Lipid peroxidation induced by reactive oxygen species might modify circulating biomolecules because of the formation of alpha,beta-unsaturated or dicarbonylic aldehydes. In order to investigate the interaction between a lipoperoxidation product, acrolein, and a circulating protein, insulin, the acrolein-insulin adduct was obtained. To characterize the adduct, gel filtration chromatography, sodium dodecylsulfate-polyacrylamide gel electrophoresis and carbonyl determination were performed. Induction of hypoglycemia in the rat and stimulation of glucose uptake by 3T3 adipocytes were used to evaluate the biological efficiency of the adduct compared with that of native insulin (Mackness, B., Quarck, R., Verte, W., Mackness, M., and Holvoet, P. (2006) Arterioscler., Thromb. Vasc. Biol. 26, 1545-1550). Formation of the acrolein-insulin complex in vitro increased the carbonyl group concentration from 2.5 to 22.5 nmol/mg of protein, and it formed without intermolecular aggregates (Halliwell, B., and Whiteman, M. (2004) Br. J. Pharmacol. 142, 231-255. The hypoglycaemic effect 18 min after administration to the rat is decreased by 25% (Robertson, R. P. (2004) J. Biol. Chem. 279, 42351-42354. An adduct concentration of 94 nM, compared to 10 nM for native insulin, was required to obtain the A 50% (concentration needed to obtain 50% of maximum transport of glucose uptake by 3T3 adipocytes). In conclusion, formation of the acrolein-insulin adduct modifies the structure of insulin and decreases its hypoglycemic effect in rat and glucose uptake by 3T3 adipocytes. These results help explain how a toxic aldehyde prone to be produced in vivo can structurally modify insulin and change its biological action.

In parkinsonian substantia nigra, α-synuclein is modified by acrolein, a lipid-peroxidation product, and accumulates in the dopamine neurons with inhibition of proteasome activity

alpha-Synuclein (alphaSYN) plays a central role in the neural degeneration of Parkinson's disease (PD) through its conformational change. In PD, alphaSYN, released from the membrane, accumulates in the cytoplasm and forms Lewy body. However, the mechanism behind the translocation and conformational change of alphaSYN leading to the cell death has not been well elucidated. This paper reports that in the dopamine neurons of the substantia nigra containing neuromelanin from PD patients, alphaSYN was modified with acrolein (ACR), an aldehyde product of lipid peroxidation. Histopathological observation confirmed the co-localization of protein immunoreactive to anti-alphaSYN and ACR antibody. By Western blot analyses of samples precipitated with either anti-alphaSYN or anti-ACR antibody, increase in ACR-modified alphaSYN was confirmed in PD brain. Modification of recombinant alphaSYN by ACR enhanced its oligomerization, and at higher ACR concentrations alphaSYN was fragmented and polymerized forming a smear pattern in SDS-PAGE. ACR reduced 20S proteasome activity through the direct modification of the proteasome proteins and the production of polymerized ACR-modified proteins, which inhibited proteasome activity in vitro. These results suggest that ACR may initiate vicious cycle of modification and aggregation of proteins, including alphaSYN, and impaired proteolysis system, to cause neuronal death in PD.

Pollinator and herbivore attraction to cucurbita floral volatiles

Mutualists and antagonists may place conflicting selection pressures on plant traits. For example, the evolution of floral traits is typically studied in the context of attracting pollinators, but traits may incur fitness costs if they are also attractive to antagonists. Striped cucumber beetles (Acalymma vittatum) feed on cucurbits and are attracted to several volatiles emitted by Cucurbita blossoms. However, the effect of these volatiles on pollinator attraction is unknown. Our goal was to determine whether pollinators were attracted to the same or different floral volatiles as herbivorous cucumber beetles. We tested three volatiles previously found to attract cucumber beetles in a factorial design to determine attraction of squash bees (Peponapis pruinosa), the specialist pollinators of cucurbita species, as well as the specialist herbivore A. vittatum. We found that 1,2,4-trimethoxybenzene was attractive to both the pollinator and the herbivore, indole was attractive only to the herbivore, and (E)-cinnamaldehyde was attractive only to the pollinator. There were no interactions among volatiles on attraction of squash bees or cucumber beetles. Our results suggest that reduced indole emission could benefit plants by reducing herbivore attraction without loss of pollination, and that 1,2,4-trimethoxybenzene might be under conflicting selection pressure from mutualists and antagonists. By examining the attraction of both mutualists and antagonists to Cucurbita floral volatiles, we have demonstrated the potential for some compounds to influence only one type of interaction, while others may affect both interactions and possibly result in tradeoffs. These results shed light on the potential evolution of fragrance in native Cucurbita, and may have consequences for yield in agricultural settings.

Characterization of acrolein-glycerophosphoethanolamine lipid adducts using electrospray mass spectrometry

Acrolein is a toxic, highly reactive alpha,beta-unsaturated aldehyde. In the current study, the products of acrolein after reaction with glycerophosphoethanolamine (GPEtn) lipids have been characterized using electrospray tandem mass spectrometry. The major product formed involves the addition of two acrolein molecules to the primary amine of GPEtn lipids and subsequent aldol condensation to form 1,2-diradyl- sn-glycero-3-phosphoethanol-(3-formyl-4-hydroxy)piperidine (FHP) lipids. Upon sodium borohydride reduction, 1,2-diradyl- sn-glycero-3-phosphoethanol-(3-hydroxymethyl-4-hydroxy)piperidine (HMHP) lipids and 1,2-diradyl- sn-glycero-3-phosphoethanol-(3-hydroxymethyl-3,4-dehydro)piperidine (HMDP) lipids were selectively detected using electrospray tandem mass spectrometry by employing precursors of m/ z 256.1 and 238.1 scans, respectively. HMHP lipid and HMDP lipid molecular species were detected upon treatment of HL-60 cells with concentrations of acrolein as low as 10 microM. While the biological implications of these acrolein GPEtn adducts have yet to be established, these structural characterization studies reported herein reveal the facile formation of acrolein GPEtn lipid adducts in vitro, which could influence subsequent biochemical events within the cell.

Quantitation of acrolein-derived (3-hydroxypropyl)mercapturic acid in human urine by liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry: effects of cigarette smoking

Recently published data suggest that acrolein (1), a toxic but weakly carcinogenic constituent of cigarette smoke, may be involved as a causative factor for the mutations frequently observed in the p53 tumor suppressor gene in lung cancer in smokers. Biomarkers are needed to further assess the possible relationship between acrolein uptake and cancer. In this study, we analyzed (3-hydroxypropyl)mercapturic acid (3-HPMA, 2) in human urine. 3-HPMA is a major metabolite of acrolein in laboratory animals. The method employs [13C3]3-HPMA as an internal standard, with analysis and quantitation by LC-APCI-MS/MS-SRM. Clean, readily quantifiable chromatograms were obtained. The method was accurate and precise and required only 0.1 mL of urine. Median levels of 3-HPMA were significantly higher (2900 pmol/mg of creatinine, N=35) in smokers than in nonsmokers (683 pmol/mg of creatinine, N=21) (P=0.0002). The effect of smoking was further assessed by determining the levels of 3-HPMA before and after a 4 week smoking cessation period. There was a significant 78% decrease in median levels of urinary 3-HPMA after cessation (P<0.0001). The relationship between the levels of urinary 3-HPMA and those of acrolein-derived 1,N2-propanodeoxyguanosine (PdG) adducts in lung was investigated in 14 smokers. There was a significant inverse relationship between urinary 3-HPMA and alpha-hydroxy-PdG (3) but not gamma-hydroxy-PdG (4) or total adduct levels. The results of this study clearly demonstrate that acrolein uptake in smokers is significantly higher than in nonsmokers and underline the need for further investigation of the possible relationship of acrolein uptake to lung cancer.

Alpha,beta-unsaturated aldehydes adducts to actin and albumin as potential biomarkers of carbonylation damage

Reactive carbonyl species (RCS) generated by lipid peroxidation, leading to protein carbonylation, are involved in several human diseases. Protein carbonylation constitutes one of the best characterised biomarker of oxidative damage to proteins. Albumin and actin have been identified, through different proteomic approaches, as the main protein targets for RCS in plasma and tissues, respectively. By a combined LC-MS/MS and computational approach, we have demonstrated their high reactivity towards alpha,beta-unsaturated aldehydes, and established the stoichiometry of reaction with HNE and acrolein, as well as the amino acid residues more susceptible to carbonyl attack. A new mass spectrometric approach, based on LC-MS/MS analysis of tag HNE/ACR-modified peptides of carbonylated albumin and actin is proposed, and the advantages over the conventional methods for RCS and RCS-adducted protein analyses discussed.

The concept of "aldehyde load" in neurodegenerative mechanisms: cytotoxicity of the polyamine degradation products hydrogen peroxide, acrolein, 3-aminopropanal, 3-acetamidopropanal and 4-aminobutanal in a retinal ganglion cell line

In neurodegenerative diseases augmented polyamine metabolism results in the generation of hydrogen peroxide and a number of reactive aldehydes that participate in the death of compromised tissue. The major aldehydes produced by polyamine oxidase and amine oxidases include the 2-alkenal acrolein, the acetoamidoaldehyde 3-acetamidopropanal (3-AAP) and the aminoaldehydes 3-aminopropanal (3-AP) and 4-aminobutanal (4-AB). Using retinal ganglion cell (E1A-NR.3) cultures, we confirmed the cytotoxicity of acrolein and 3-AP. For the first time we also demonstrated the cytotoxicity of 4-AB and the lack of toxicity of 3-AAP. Our data with 3-AAP, a product of N-acetylspermine and N-acetylspermidine metabolism, indicate that the aldehyde function of aminoaldehydes is insufficient to express toxicity since the free amino group of aminoaldehydes is also required to gain access to lysosomes where their cytotoxic actions are expressed via leakage of cathepsins that compromise mitochondrial integrity. Metabolism of 3-AP to beta-alanine by aldehyde dehydrogenase was also evaluated in retinal ganglion cell cultures and found to proceed at a linear rate of 24.3+/-1 nmol/mg protein/h. These are the first data demonstrating the dynamic cellular detoxification of 3-AP by neural cells and support the concept that decrements in aldehyde elimination leading to an increase in "aldehyde load" may play pivotal roles in the development and progression of neurodegenerative diseases such as Alzheimer's disease, multiple sclerosis and Parkinson's disease.

Activation of the death receptor pathway of apoptosis by the aldehyde acrolein

Reactive alpha,beta-unsaturated aldehydes such as acrolein are major components of common environmental pollutants. As a toxic by-product of lipid peroxidation, acrolein has been implicated as a possible mediator of oxidative damage to cells and tissues in a wide variety of disease states, including atherosclerosis and neurodegenerative and pulmonary diseases. Although acrolein can induce apoptotic cell death in various cell types, the biochemical mechanisms are not understood. This study investigates the implication of the death receptor pathway in acrolein-induced apoptosis. Exposure of Chinese hamster ovary cells to acrolein caused translocation of adaptor protein Fas associated with death domain to the cytoplasmic membrane and caspase-8 activation. Kp7-6, an antagonist of Fas receptor activation, blocked apoptotic events downstream of caspase-8, such as caspase-7 activation and nuclear chromatin condensation. Acrolein activated the cross-talk pathway between the death receptor and mitochondrial pathways. Bid was cleaved to truncated-Bid, which was translocated to mitochondria. Activation of the mitochondrial pathway by acrolein was confirmed by caspase-9 activation. Inhibition of activation of either the Fas receptor or caspase-8 partially decreased acrolein-induced caspase-9 activation. These findings indicate that acrolein activates the Fas receptor pathway, which occurs upstream of the mitochondrial pathway. Caspase-9 activation still occurred despite inhibition of the Fas receptor pathway, suggesting that acrolein could also trigger the mitochondrial pathway independent of the receptor pathway. These findings improve our understanding of mechanisms of toxicity of the reactive aldehyde acrolein, which has widespread implications in multiple disease states which seem to be mediated by oxidative stress and lipid peroxidation.

Acrolein induces cyclooxygenase-2 and prostaglandin production in human umbilical vein endothelial cells: roles of p38 MAP kinase

OBJECTIVE

Acrolein, a known toxin in tobacco smoke, might be involved in atherogenesis. This study examined the effect of acrolein on expression of cyclooxygenase-2 (COX-2) and prostaglandin (PG) production in endothelial cells.

METHODS AND RESULTS

Cyclooxygenase (COX)-2 induction by acrolein and signal pathways were measured using Western blots, Northern blots, immunofluorescence, ELISA, gene silencing, and promoter assay. Colocalization of COX2 and acrolein-adduct was determined by immunohistochemistry. Here we report that the levels of COX-2 mRNA and protein are increased in human umbilical vein endothelial cells (HUVECs) after acrolein exposure. COX-2 was found to colocalize with acrolein-lysine adducts in human atherosclerotic lesions. Inhibition of p38 MAPK activity abolished the induction of COX-2 protein and PGE2 accumulation by acrolein, while suppression of extracellular signal-regulated kinase (ERK) and JNK activity had no effect on the induction of COX-2 expression in experiments using inhibitors and siRNA. Furthermore, rottlerin, an inhibitor of protein kinase Cdelta (PKCdelta), abrogated the upregulation of COX-2 at both protein and mRNA levels.

CONCLUSION

These results provide that acrolein may play a role in progression of atherosclerosis and new information on the signaling pathways involved in COX-2 upregulation in response to acrolein and provide evidence that PKCdelta and p38 MAPK are required for transcriptional activation of COX-2.

Noxious compounds activate TRPA1 ion channels through covalent modification of cysteines

The nervous system senses peripheral damage through nociceptive neurons that transmit a pain signal. TRPA1 is a member of the Transient Receptor Potential (TRP) family of ion channels and is expressed in nociceptive neurons. TRPA1 is activated by a variety of noxious stimuli, including cold temperatures, pungent natural compounds, and environmental irritants. How such diverse stimuli activate TRPA1 is not known. We observed that most compounds known to activate TRPA1 are able to covalently bind cysteine residues. Here we use click chemistry to show that derivatives of two such compounds, mustard oil and cinnamaldehyde, covalently bind mouse TRPA1. Structurally unrelated cysteine-modifying agents such as iodoacetamide (IA) and (2-aminoethyl)methanethiosulphonate (MTSEA) also bind and activate TRPA1. We identified by mass spectrometry fourteen cytosolic TRPA1 cysteines labelled by IA, three of which are required for normal channel function. In excised patches, reactive compounds activated TRPA1 currents that were maintained at least 10 min after washout of the compound in calcium-free solutions. Finally, activation of TRPA1 by disulphide-bond-forming MTSEA is blocked by the reducing agent dithiothreitol (DTT). Collectively, our data indicate that covalent modification of reactive cysteines within TRPA1 can cause channel activation, rapidly signalling potential tissue damage through the pain pathway.

[Chemistry and toxicology of cigarette smoke in the lungs]

Cigarettes appearance in the middle of 19th century turns tobacco into a general consumption product with ill-fated consequences. Technological process and the means by which tobacco dependence appears were hidden from medical world for a long time by the tobacco companies. Cigarette smoke represents a mixture of 4000 toxic substances including carcinogens, organic compounds, solvents, gas substances (CO). We can add another 600 additives which are used in the technological process. Tobacco dependence is defined by the daily cigarette consumption, difficult quitting and probability for withdraw symptoms. Among the smoke effects on respiratory system, we can identify two main mechanisms: inducing inflammation and mutagen if - carcinogenic effect. Inflammation consists of ciliary toxicity, increased mucus secretion and accumulation of activated inflammatory cells in the respiratory tract. The risk for lung cancer is directly related to the presence of CYPlA1 alleles and reduced glutathione S-reductase activity.

Acrolein is a major cigarette-related lung cancer agent: Preferential binding at p53 mutational hotspots and inhibition of DNA repair

The tumor suppressor gene p53 is frequently mutated in cigarette smoke (CS)-related lung cancer. The p53 binding pattern of carcinogenic polycyclic aromatic hydrocarbons (PAHs) found in CS coincides with the p53 mutational pattern found in lung cancer, and PAHs have thus been considered to be major culprits for lung cancer. However, compared with other carcinogenic compounds, such as aldehydes, the amount of PAHs in CS is minute. Acrolein (Acr) is abundant in CS, and it can directly adduct DNA. Acr-DNA adducts, similar to PAH-DNA adducts, induce predominantly G-to-T transversions in human cells. These findings raise the question of whether Acr-DNA adducts are responsible for p53 mutations in CS-related lung cancer. To determine the role of Acr-DNA adducts in p53 mutagenesis in CS-related lung cancer we mapped the distribution of Acr-DNA adducts at the sequence level in the p53 gene of lung cells using the UvrABC incision method in combination with ligation-mediated PCR. We found that the Acr-DNA binding pattern is similar to the p53 mutational pattern in human lung cancer. Acr preferentially binds at CpG sites, and this enhancement of binding is due to cytosine methylation at these sequences. Furthermore, we found that Acr can greatly reduce the DNA repair capacity for damage induced by benzo[a]pyrene diol epoxide. Together these results suggest that Acr is a major etiological agent for CS-related lung cancer and that it contributes to lung carcinogenesis through two detrimental effects: DNA damage and inhibition of DNA repair.

Aldehyde load in ischemia-reperfusion brain injury: neuroprotection by neutralization of reactive aldehydes with phenelzine

In ongoing studies of the neuroprotective properties of monoamine oxidase inhibitors, we found that phenelzine provided robust neuroprotection in the gerbil model of transient forebrain ischemia, with drug administration delayed up to 3 h post reperfusion. Since ischemia-reperfusion brain injury is associated with large increases in the concentrations of reactive aldehydes in the penumbra area, we investigated if the hydrazine function of phenelzine was capable of sequestering reactive aldehydes. Both aminoaldehydes and acrolein are generated from the metabolism of polyamines to putrescine by polyamine oxidase. These toxic aldehydes in turn compromise mitochondrial and lysosomal integrity and initiate apoptosis and necrosis. Previous studies have demonstrated that pharmacological neutralization of reactive aldehydes via the formation of thioacetal derivatives results in significant neuroprotection in ischemia-reperfusion injury, in both focal and global ischemia models. In our studies of acrolein and 3-aminopropanal toxicity, using an immortalized retinal cell line, we found that aldehyde sequestration with phenelzine was neuroprotective. The neuroprotection observed with phenelzine is in agreement with previous studies of aldehyde sequestering agents in the treatment of ischemia-reperfusion brain injury and supports the concept that "aldehyde load" is a major factor in the delayed cell losses of the ischemic penumbra.

Raman imaging to investigate ultrastructure and composition of plant cell walls: distribution of lignin and cellulose in black spruce wood (Picea mariana)

A detailed understanding of the structural organization of the cell wall of vascular plants is important from both the perspectives of plant biology and chemistry and of commercial utilization. A state-of-the-art 633-nm laser-based confocal Raman microscope was used to determine the distribution of cell wall components in the cross section of black spruce wood in situ. Chemical information from morphologically distinct cell wall regions was obtained and Raman images of lignin and cellulose spatial distribution were generated. While cell corner (CC) lignin concentration was the highest on average, lignin concentration in compound middle lamella (CmL) was not significantly different from that in secondary wall (S2 and S2-S3). Images generated using the 1,650 cm(-1) band showed that coniferaldehyde and coniferyl alcohol distribution followed that of lignin and no particular cell wall layer/region was therefore enriched in the ethylenic residue. In contrast, cellulose distribution showed the opposite pattern-low concentration in CC and CmL and high in S2 regions. Nevertheless, cellulose concentration varied significantly in some areas, and concentrations of both lignin and cellulose were high in other areas. Though intensity maps of lignin and cellulose distributions are currently interpreted solely in terms of concentration differences, the effect of orientation needs to be carefully considered to reveal the organization of the wood cell wall.

Acrolein generation stimulates hypercontraction in isolated human blood vessels

Increased risk of vasospasm, a spontaneous hyperconstriction, is associated with atherosclerosis, cigarette smoking, and hypertension-all conditions involving oxidative stress, lipid peroxidation, and inflammation. To test the role of the lipid peroxidation- and inflammation-derived aldehyde, acrolein, in human vasospasm, we developed an ex vivo model using human coronary artery bypass graft (CABG) blood vessels and a demonstrated acrolein precursor, allylamine. Allylamine induces hypercontraction in isolated rat coronary artery in a semicarbazide-sensitive amine oxidase activity (SSAO) dependent manner. Isolated human CABG blood vessels (internal mammary artery, radial artery, saphenous vein) were used to determine: (1) vessel responses and sensitivity to acrolein, allylamine, and H(2)O(2) exposure (1 microM-1 mM), (2) SSAO dependence of allylamine-induced effects using SSAO inhibitors (semicarbazide, 1 mM; MDL 72274-E, active isomer; MDL 72274-Z, inactive isomer; 100 microM), (3) the vasoactive effects of two other SSAO amine substrates, benzylamine and methylamine, and (4) the contribution of extracellular Ca(2+) to hypercontraction. Acrolein or allylamine but not H(2)O(2), benzylamine, or methylamine stimulated spontaneous and pharmacologically intractable hypercontraction in CABG blood vessels that was similar to clinical vasospasm. Allylamine-induced hypercontraction and blood vessel SSAO activity were abolished by pretreatment with semicarbazide or MDL 72274-E but not by MDL 72274-Z. Allylamine-induced hypercontraction also was significantly attenuated in Ca(2+)-free buffer. In isolated aorta of spontaneously hypertensive rat, allylamine-induced an SSAO-dependent contraction and enhanced norepinephrine sensitivity but not in Sprague-Dawley rat aorta. We conclude that acrolein generation in the blood vessel wall increases human susceptibility to vasospasm, an event that is enhanced in hypertension.