Third-Hand Exposure to E-Cigarette Vapour Induces Pulmonary Effects in Mice.

In the last decade, e-cigarette usage has increased, with an estimated 82 million e-cigarette users globally. This is, in part, due to the common opinion that they are "healthier" than tobacco cigarettes or simply "water vapour". Third-hand e-vapour exposure is the chemical residue left behind from e-cigarette aerosols, which is of concern due to its invisible nature, especially among young children. However, there is limited information surrounding third-hand e-vapour exposure. This study aimed to investigate the pulmonary effects of sub-chronic third-hand e-vapour exposure in a murine model. BALB/c mice (4 weeks of age) were exposed to a towel containing nicotine free (0 mg) e-vapour, nicotine (18 mg) e-vapour, or no e-vapour (sham) and replaced daily for 4 weeks. At the endpoint, lung function was assessed, and bronchoalveolar lavage fluid and lungs were collected to measure inflammation and fibrosis. Mice exposed to third-hand e-vapour without nicotine had alveolar enlargement compared to sham exposed controls. Mice exposed to third-hand e-vapour with nicotine had reduced bronchial responsiveness to provocation, increased epithelial thickening in large airways, increased epithelial layers in small airways, alveolar enlargement, and increased small airway collagen deposition, compared to sham exposed controls. In conclusion, our study shows that third-hand e-vapour exposure, particularly in the presence of nicotine, negatively affects the lung health of mice and highlights the need for greater public awareness surrounding the dangers of third-hand exposure to e-cigarette vapour.

Sex-Dependent Responses to Maternal Exposure to PM2.5 in the Offspring.

Objective: Particulate matter (PM) with a diameter of 2.5 µm or less (PM2.5) can cross the blood-placental barrier causing adverse foetal outcomes. However, the impact of maternal exposure to low-levels of PM2.5 on liver health and the metabolic profile is unclear. This study aimed to investigate hepatic responses to long-term gestational low-dose PM2.5 exposure, and whether the removal of PM after conception can prevent such effects. Method: Female Balb/c mice (8 weeks) were exposed to PM2.5 (5 µg/day) for 6 weeks prior to mating, during gestation and lactation to model living in a polluted environment (PM group). In a sub-group, PM2.5 exposure was stopped post-conception to model mothers moving to areas with clean air (pre-gestation, Pre) group. Livers were studied in 13-week old offspring. Results: Female offspring in both PM and Pre groups had increased liver triglyceride and glycogen levels, glucose intolerance, but reduced serum insulin and insulin resistance. Male offspring from only the Pre group had increased liver and serum triglycerides, increased liver glycogen, glucose intolerance and higher fasting glucose level. Markers of oxidative stress and inflammation were increased in females from PM and Pre groups. There was also a significant sex difference in the hepatic response to PM2.5 with differential changes in several metabolic markers identified by proteomic analysis. Conclusions: Maternal PM exposure exerted sex-dependent effects on liver health with more severe impacts on females. The removal of PM2.5 during gestation provided limited protection in the offspring's metabolism regardless of sex.

A comparison of attitudes toward remote learning during the COVID-19 pandemic between students attending a Chinese and an Australian campus.

The COVID-19 pandemic has been a strong driver for moving more teaching and learning activities online. Border restrictions have had a severe impact on international students either hoping to enroll in courses offered in Australia or continue with such courses if they are already enrolled. The online learning experience is likely different between students onshore and offshore. This study took a unique opportunity to investigate any such differences in students' attitudes toward remote learning, necessitated by the pandemic, by comparing two cohorts of students, Australia versus China based. An anonymous survey using the Likert Scale and open-ended questions was available for student feedback on subject delivery. The students based in Australia expressed a preference for remote learning due to the convenience of attendance and availability of the video recordings. However, students in China had a strong preference for face-to-face sessions, with the lack of prior experience in an English-speaking learning environment and hesitance to speak with the lecturers and engage in the learning activities possible reasons for this. In quizzes, students in Australia performed better than those in China regardless of local or international student status. This difference may be due to the Australian-based students' prior experience of English-speaking environments and open-book quizzes. In conclusion, remote learning in a familiar language and learning environment is accepted by students, whereas if the teaching is delivered in a second language using unfamiliar teaching methods, remote learning will require additional scaffolding to enhance their learning experience.

Extracellular Matrix Oxidised by the Granulocyte Oxidants Hypochlorous and Hypobromous Acid Reduces Lung Fibroblast Adhesion and Proliferation In Vitro.

Chronic airway inflammation and oxidative stress play crucial roles in the pathogenesis of chronic inflammatory lung diseases, with airway inflammation being a key driving mechanism of oxidative stress in the lungs. Inflammatory responses in the lungs activate neutrophils and/or eosinophils, leading to the generation of hypohalous acids (HOX). These HOX oxidants can damage the extracellular matrix (ECM) structure and may influence cell-ECM interactions. The ECM of the lung provides structural, mechanical, and biochemical support for cells and determines the airway structure. One of the critical cells in chronic respiratory disease is the fibroblast. Thus, we hypothesised that primary human lung fibroblasts (PHLF) exposed to an oxidised cell-derived ECM will result in functional changes to the PHLF. Here, we show that PHLF adhesion, proliferation, and inflammatory cytokine secretion is affected by exposure to HOX-induced oxidisation of the cell-derived ECM. Furthermore, we investigated the impact on fibroblast function from the presence of haloamines in the ECM. Haloamines are chemical by-products of HOX and, like the HOX, haloamines can also modify the ECM. In conclusion, this study revealed that oxidising the cell-derived ECM might contribute to functional changes in PHLF, a key mechanism behind the pathogenesis of inflammatory lung diseases.

Modulation of neural regulators of energy homeostasis, and of inflammation, in the pups of mice exposed to e-cigarettes.

BACKGROUND: Maternal smoking can lead to perturbations in central metabolic regulators such as neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) signalling components in offspring. With the growing interest in e-cigarettes as a tobacco replacement, this short report assessed central metabolic regulation in offspring of mouse dams exposed to e-cigarettes. We examined the impact of continuous use of e-cigarettes, and e-cigarette replacement of tobacco cigarettes during pregnancy. Supplementation of an antioxidant l-carnitine was also co-used with tobacco cigarette in the mother to determine whether the impact of maternal tobacco smoking was oxidative stress driven. METHODS: Balb/c mice were exposed to either nicotine-containing (E-cig18) or nicotine-free (E-cig0) e-cigarette aerosols or tobacco smoke (SE) prior to mating and until their pups were weaned. After mating, two SE sub-groups were changed to E-cig18 exposure (Replacement), or supplementation l-carnitine while SE was continued. Male offspring were studied at weaning age. RESULTS: The offspring of E-cig0 dams were the heaviest with the most body fat. Replacing SE with E-cig18 during pregnancy resulted in offspring with significantly less body fat. E-cig0 offspring had significantly increased mRNA expression of brain NPY and iNOS. Maternal SE upregulated mRNA expression of NPY, NPY Y1 receptor, POMC downstream components, and iNOS expression, which were normalised in Replacement offspring, but only partially normalised with maternal L-carnitine supplementation during gestation and lactation. CONCLUSIONS: Maternal exposure to either tobacco and nicotine-free e-cigarettes lead to disturbances in the level of central homeostatic control markers in offspring, suggesting that maternal exposure to e-cigarettes is not without risks.

A pivotal role for NF-κB in the macrophage inflammatory response to the myeloperoxidase oxidant hypothiocyanous acid.

Atherosclerosis is characterised by the infiltration of macrophages at sites of inflammation within the vessel wall and the release of myeloperoxidase (MPO), which forms hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN). HOCl is a damaging oxidant implicated in the development of atherosclerosis. Preferential formation of HOSCN occurs under conditions where thiocyanate ions are elevated, as is the case in smokers. HOSCN reacts selectively with thiols, which can result in more enzyme inactivation and damage than HOCl at susceptible sites, which may contribute to atherosclerosis in smokers. In this study, we show that exposure of macrophages to HOSCN results in a time- and dose-dependent increase in the mRNA expression and release of pro-inflammatory cytokines and chemokines, including monocyte chemotactic protein 1, tumour necrosis factor alpha, and interleukins 6, 8 and 1ß. At high oxidant concentrations (>200 µM), a significant loss of cellular thiols and increased cell death is observed. HOSCN-induced cytokine/chemokine expression and cell death were decreased on pharmacological inhibition of nuclear factor kappa B. These data highlight a pathway by which HOSCN could promote inflammation and the development of atherosclerosis, in the presence of supra-physiological levels of the precursor thiocyanate, which are achievable by cigarette smoking.

Evidence of Biomass Smoke Exposure as a Causative Factor for the Development of COPD.

Chronic obstructive pulmonary disease (COPD) is a progressive disease of the lungs characterised by chronic inflammation, obstruction of airways, and destruction of the parenchyma (emphysema). These changes gradually impair lung function and prevent normal breathing. In 2002, COPD was the fifth leading cause of death, and is estimated by the World Health Organisation (WHO) to become the third by 2020. Cigarette smokers are thought to be the most at risk of developing COPD. However, recent studies have shown that people with life-long exposure to biomass smoke are also at high risk of developing COPD. Most common in developing countries, biomass fuels such as wood and coal are used for cooking and heating indoors on a daily basis. Women and children have the highest amounts of exposures and are therefore more likely to develop the disease. Despite epidemiological studies providing evidence of the causative relationship between biomass smoke and COPD, there are still limited mechanistic studies on how biomass smoke causes, and contributes to the progression of COPD. This review will focus upon why biomass fuels are used, and their relationship to COPD. It will also suggest methodological approaches to model biomass exposure in vitro and in vivo.

Low-density lipoprotein modified by myeloperoxidase oxidants induces endothelial dysfunction.

Low-density lipoprotein (LDL) modified by hypochlorous acid (HOCl) produced by myeloperoxidase (MPO) is present in atherosclerotic lesions, where it is implicated in the propagation of inflammation and acceleration of lesion development by multiple pathways, including the induction of endothelial dysfunction. Thiocyanate (SCN-) ions are utilised by MPO to produce the oxidant hypothiocyanous acid (HOSCN), which reacts with LDL in a different manner to HOCl. Whilst the reactivity of HOCl-modified LDL has been previously studied, the role of HOSCN in the modification of LDL in vivo is poorly defined, although emerging evidence suggests that these particles have distinct biological properties. This is important because elevated plasma SCN- is linked with both the propagation and prevention of atherosclerosis. In this study, we demonstrate that both HOSCN- and HOCl-modified LDL inhibit endothelium-mediated vasorelaxation ex vivo in rat aortic ring segments. In vitro experiments with human coronary artery endothelial cells show that HOSCN-modified LDL decreases in the production of nitric oxide (NO•) and induces the loss of endothelial nitric oxide synthase (eNOS) activity. This occurs to a similar extent to that seen with HOCl-modified LDL. In each case, these effects are related to eNOS uncoupling, rather than altered expression, phosphorylation or cellular localisation. Together, these data provide new insights into role of MPO and LDL modification in the induction of endothelial dysfunction, which has implications for both the therapeutic use of SCN- within the setting of atherosclerosis and for smokers, who have elevated plasma levels of SCN-, and are more at risk of developing cardiovascular disease.

The use of simulation as a novel experiential learning module in undergraduate science pathophysiology education.

Teaching of pathophysiology concepts is a core feature in health professional programs, but it can be challenging in undergraduate medical/biomedical science education, which is often highly theoretical when delivered by lectures and pen-and-paper tutorials. Authentic case studies allow students to apply their theoretical knowledge but still require good imagination on the part of the students. Lecture content can be reinforced through practical learning experiences in clinical environments. In this study, we report a new approach using clinical simulation within a Human Pathophysiology course to enable undergraduate science students to see "pathophysiology in action" in a clinical setting. Students role played health professionals, and, in these roles, they were able to interact with each other and the manikin "patient," take a medical history, perform a physical examination and consider relevant treatments. Evaluation of students' experiences suggests that using clinical simulation to deliver case studies is more effective than traditional paper-based case studies by encouraging active learning and improving the understanding of physiological concepts.

The nitroxide radical TEMPOL prevents obesity, hyperlipidaemia, elevation of inflammatory cytokines, and modulates atherosclerotic plaque composition in apoE-/- mice.

OBJECTIVE: The nitroxide compound TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl radical) has been shown to prevent obesity-induced changes in adipokines in cell and animal systems. In this study we investigated whether supplementation with TEMPOL inhibits inflammation and atherosclerosis in apoE-/- mice fed a high fat diet (HFD). METHODS: ApoE-/- mice were fed for 12 weeks on standard chow diet or a high-fat diet. Half the mice were supplemented with 10 mg/g TEMPOL in their food. Plasma samples were analysed for triglycerides, cholesterol, low- and high-density lipoprotein cholesterol, inflammatory cytokines and markers (interleukin-6, IL-6; monocyte-chemotactic protein, MCP-1; myeloperoxidase, MPO; serum amyloid A, SAA; adiponectin; leptin). Plaques in the aortic sinus were analysed for area, and content of collagen, lipid, macrophages and smooth muscle cells. RESULTS: High fat feeding resulted in marked increases in body mass and plasma lipid levels. Dietary TEMPOL decreased both parameters. In the high-fat-fed mice significant elevations in plasma lipid levels and the inflammatory markers IL-6, MCP-1, MPO, SAA were detected, along with an increase in leptin and a decrease in adiponectin. TEMPOL supplementation reversed these effects. When compared to HFD-fed mice, TEMPOL supplementation increased plaque collagen content, decreased lipid content and increased macrophage numbers. CONCLUSIONS: These data indicate that in a well-established model of obesity-associated hyperlipidaemia and atherosclerosis, TEMPOL had a significant impact on body mass, atherosclerosis, hyperlipidaemia and inflammation. TEMPOL may therefore be of value in suppressing obesity, metabolic disorders and increasing atherosclerotic plaque stability.

Comparative reactivity of the myeloperoxidase-derived oxidants HOCl and HOSCN with low-density lipoprotein (LDL): Implications for foam cell formation in atherosclerosis.

Atherosclerosis is characterised by the accumulation of lipids within macrophages in the artery wall. Low-density lipoprotein (LDL) is the source of this lipid, owing to the uptake of oxidised LDL by scavenger receptors. Myeloperoxidase (MPO) released by leukocytes during inflammation produces oxidants that are implicated in atherosclerosis. Modification of LDL by the MPO oxidant hypochlorous acid (HOCl), results in extensive lipid accumulation by macrophages. However, the reactivity of the other major MPO oxidant, hypothiocyanous acid (HOSCN) with LDL is poorly characterised, which is significant given that thiocyanate is the favoured substrate for MPO. In this study, we comprehensively compare the reactivity of HOCl and HOSCN with LDL, and show key differences in the profile of oxidative damage observed. HOSCN selectively modifies Cys residues on apolipoprotein B100, and oxidises cholesteryl esters resulting in formation of lipid hydroperoxides, 9-hydroxy-10,12-octadecadienoic acid (9-HODE) and F2-isoprostanes. The modification of LDL by HOSCN results macrophage lipid accumulation, though generally to a lesser extent than HOCl-modified LDL. This suggests that a change in the ratio of HOSCN:HOCl formation by MPO from variations in plasma thiocyanate levels, will influence the nature of LDL oxidation in vivo, and has implications for the progression of atherosclerosis.

Supplementation with carnosine decreases plasma triglycerides and modulates atherosclerotic plaque composition in diabetic apo E(-/-) mice.

OBJECTIVE: Carnosine has been shown to modulate triglyceride and glycation levels in cell and animal systems. In this study we investigated whether prolonged supplementation with carnosine inhibits atherosclerosis and markers of lesion stability in hyperglycaemic and hyperlipidaemic mice. METHODS: Streptozotocin-induced diabetic apo E(-/-) mice were maintained for 20 weeks, post-induction of diabetes. Half of the animals received carnosine (2g/L) in their drinking water. Diabetes was confirmed by significant increases in blood glucose and glycated haemoglobin, plasma triglyceride and total cholesterol levels, brachiocephalic artery and aortic sinus plaque area; and lower body mass. RESULTS: Prolonged carnosine supplementation resulted in a significant (∼20-fold) increase in plasma carnosine levels, and a significant (∼23%) lowering of triglyceride levels in the carnosine-supplemented groups regardless of glycaemic status. Supplementation did not affect glycaemic status, blood cholesterol levels or loss of body mass. In the diabetic mice, carnosine supplementation did not diminish measured plaque area, but reduced the area of plaque occupied by extracellular lipid (∼60%) and increased both macrophage numbers (∼70%) and plaque collagen content (∼50%). The area occupied by α-actin-positive smooth muscle cells was not significantly increased. CONCLUSIONS: These data indicate that in a well-established model of diabetes-associated atherosclerosis, prolonged carnosine supplementation enhances plasma levels, and has novel and significant effects on atherosclerotic lesion lipid, collagen and macrophage levels. These data are consistent with greater lesion stability, a key goal in treatment of existing cardiovascular disease. Carnosine supplementation may therefore be of benefit in lowering triglyceride levels and suppressing plaque instability in diabetes-associated atherosclerosis.

Inhibition of lysosomal function in macrophages incubated with elevated glucose concentrations: a potential contributory factor in diabetes-associated atherosclerosis.

OBJECTIVE: People with diabetes have an elevated risk of atherosclerosis. The accumulation of lipid within macrophage cells in the artery wall is believed to arise via the uptake and subsequent processing of modified low-density lipoproteins (LDL) via the endo-lysosomal system. In this study the effects of prolonged exposure to elevated glucose upon macrophage lysosomal function was examined to determine whether this contributes to modulated protein catabolism. METHODS: Human monocytes were isolated from white-cell concentrates and differentiated, in vitro, into monocyte-derived macrophages over 11 days in medium containing 5-30 mmol/L glucose. Murine macrophage-like J774A.1 cells were incubated similarly. Lysosomal cathepsin (B, D, L and S) and acid lipase activities were assessed using fluorogenic substrates; cathepsin protein levels were examined by Western blotting. Lysosomal numbers were examined using the lysomotropic fluorescent dye LysoTracker DND-99, measurement of aryl sulfatase activity, and quantification of lysosome-associated membrane glycoprotein-1 (LAMP-1) by Western blotting. RESULTS: Exposure to elevated glucose, but not mannitol, resulted in a concentration-dependent decrease in the activity, and to a lesser extent protein levels, of four lysosomal cathepsins. Acid lipase activity was also significantly reduced. Arysulfatase activity, LAMP-1 levels and lysosomal numbers were also decreased at the highest glucose concentrations, though to a lesser extent. CONCLUSION: Long term exposure of human and murine macrophage cells to elevated glucose levels result in a depression of lysosomal proteolytic and lipase activities. This may result in decreased clearance and cellular accumulation of (lipo)proteins and contribute to the accumulation of modified proteins and lipids in diabetes-associated atherosclerosis.

Effect of exposure of human monocyte-derived macrophages to high, versus normal, glucose on subsequent lipid accumulation from glycated and acetylated low-density lipoproteins.

During atherosclerosis monocyte-derived macrophages accumulate cholesteryl esters from low-density lipoproteins (LDLs) via lectin-like oxidised LDL receptor-1 (LOX-1) and class AI and AII (SR-AI, SR-AII) and class B (SR-BI, CD36) scavenger receptors. Here we examined the hypothesis that hyperglycaemia may modulate receptor expression and hence lipid accumulation in macrophages. Human monocytes were matured into macrophages in 30 versus 5 mM glucose and receptor expression and lipid accumulation quantified. High glucose elevated LOX1 mRNA, but decreased SR-AI, SR-BI, LDLR, and CD36 mRNA. SR-BI and CD36 protein levels were decreased. Normo- and hyperglycaemic cells accumulated cholesteryl esters from modified LDL to a greater extent than control LDL, but total and individual cholesteryl ester accumulation was not affected by glucose levels. It is concluded that, whilst macrophage scavenger receptor mRNA and protein levels can be modulated by high glucose, these are not key factors in lipid accumulation by human macrophages under the conditions examined.

Deleterious effects of reactive aldehydes and glycated proteins on macrophage proteasomal function: possible links between diabetes and atherosclerosis.

People with diabetes experience chronic hyperglycemia and are at a high risk of developing atherosclerosis and microvascular disease. Reactions of glucose, or aldehydes derived from glucose (e.g. methylglyoxal, glyoxal, or glycolaldehyde), with proteins result in glycation that ultimately yield advanced glycation end products (AGE). AGE are present at elevated levels in plasma and atherosclerotic lesions from people with diabetes, and previous in vitro studies have postulated that the presence of these materials is deleterious to cell function. This accumulation of AGE and glycated proteins within cells may arise from either increased formation and/or ineffective removal by cellular proteolytic systems, such as the proteasomes, the major multi-enzyme complex that removes proteins within cells. In this study it is shown that whilst high glucose concentrations fail to modify proteasome enzyme activities in J774A.1 macrophage-like cell extracts, reactive aldehydes enhanced proteasomal enzyme activities. In contrast BSA, pre-treated with high glucose for 8 weeks, inhibited both the chymotrypsin-like and caspase-like activities. BSA glycated using methylglyoxal or glycolaldehyde, also inhibited proteasomal activity though to differing extents. This suppression of proteasome activity by glycated proteins may result in further intracellular accumulation of glycated proteins with subsequent deleterious effects on cellular function.

Hypothiocyanous acid is a more potent inducer of apoptosis and protein thiol depletion in murine macrophage cells than hypochlorous acid or hypobromous acid.

Hypohalous acids are generated by activated leucocytes, via the formation of H(2)O(2) and the release of peroxidase enzymes (myeloperoxidase and eosinophil peroxidase). These species are important bactericidal agents, but HOCl (hypochlorous acid) and HOBr (hypobromous acid) have also been implicated in tissue damage in a number of inflammatory diseases. HOSCN (hypothiocyanous acid; cyanosulfenic acid) is a milder, more thiol-specific, oxidant than HOCl or HOBr and as such may be a more potent inducer of cellular dysfunction due to selective targeting of critical thiol residues on proteins. In the present study, HOCl and HOBr are shown to react rapidly with macrophage (J774A.1) cells, resulting in a greater extent of cell lysis compared with HOSCN. However, HOSCN induces apoptosis and necrosis with greater efficacy, and at lower concentrations, than HOCl or HOBr. Apoptosis occurs in conjunction with an increased release of cytochrome c into the cytosol, but no associated increase in caspase activity. Similarly, apoptosis is observed on treating the cells in the presence of a caspase inhibitor, suggesting that it is mediated by a caspase-independent pathway. HOSCN oxidized protein thiols more efficiently than either HOCl or HOBr. The greater efficacy of HOSCN in inducing apoptosis is attributed to selective damage to critical mitochondrial membrane protein thiol groups, resulting in increased permeability and subsequent leakage of cytochrome c into the cytosol. This induction of damage by HOSCN may be of critical importance in people with elevated levels of SCN(-) (thiocyanate ions) arising from cigarette smoking, and plays a role in the pathologies associated with this biological insult.

Glycation of low-density lipoprotein results in the time-dependent accumulation of cholesteryl esters and apolipoprotein B-100 protein in primary human monocyte-derived macrophages.

Nonenzymatic covalent binding (glycation) of reactive aldehydes (from glucose or metabolic processes) to low-density lipoproteins has been previously shown to result in lipid accumulation in a murine macrophage cell line. The formation of such lipid-laden cells is a hallmark of atherosclerosis. In this study, we characterize lipid accumulation in primary human monocyte-derived macrophages, which are cells of immediate relevance to human atherosclerosis, on exposure to low-density lipoprotein glycated using methylglyoxal or glycolaldehyde. The time course of cellular uptake of low-density lipoprotein-derived lipids and protein has been characterized, together with the subsequent turnover of the modified apolipoprotein B-100 (apoB) protein. Cholesterol and cholesteryl ester accumulation occurs within 24 h of exposure to glycated low-density lipoprotein, and increases in a time-dependent manner. Higher cellular cholesteryl ester levels were detected with glycolaldehyde-modified low-density lipoprotein than with methylglyoxal-modified low-density lipoprotein. Uptake was significantly decreased by fucoidin (an inhibitor of scavenger receptor SR-A) and a mAb to CD36. Human monocyte-derived macrophages endocytosed and degraded significantly more (125)I-labeled apoB from glycolaldehyde-modified than from methylglyoxal-modified, or control, low-density lipoprotein. Differences in the endocytic and degradation rates resulted in net intracellular accumulation of modified apoB from glycolaldehyde-modified low-density lipoprotein. Accumulation of lipid therefore parallels increased endocytosis and, to a lesser extent, degradation of apoB in human macrophages exposed to glycolaldehyde-modified low-density lipoprotein. This accumulation of cholesteryl esters and modified protein from glycated low-density lipoprotein may contribute to cellular dysfunction and the increased atherosclerosis observed in people with diabetes, and other pathologies linked to exposure to reactive carbonyls.

Carnosine and its constituents inhibit glycation of low-density lipoproteins that promotes foam cell formation in vitro.

Glycation of low-density lipoprotein (LDL) by reactive aldehydes, such as glycolaldehyde, can result in the cellular accumulation of cholesterol in macrophages. In this study, it is shown that carnosine, or its constituent amino acids beta-alanine and l-histidine, can inhibit the modification of LDL by glycolaldehyde when present at equimolar concentrations to the modifying agent. This protective effect was accompanied by inhibition of cholesterol and cholesteryl ester accumulation in human monocyte-derived macrophages incubated with the glycated LDL. Thus, carnosine and its constituent amino acids may have therapeutic potential in preventing diabetes-induced atherosclerosis.

Oxysterols in biological systems: sources, metabolism and pathophysiological relevance.

Oxysterols are the 27-carbon products of cholesterol oxidation by both enzymic and non-enzymic mechanisms. Their roles in cholesterol homeostasis, as well as in diseases in which oxidative damage and lipid peroxidation are implicated (e.g. atherosclerosis), have been investigated extensively. However, there are a number of important considerations regarding the physiological/pathophysiological functions and activities of the different oxysterols. First, in both normal and diseased tissues, the levels of oxysterols are very low when compared to the native sterol. Also, when assessing studies that have measured the levels of oxysterols in biological samples, there must be careful consideration as to the method of sample isolation, storage and sampling. This is because of the potential generation or loss of oxysterols during these procedures. Additionally, the relevance of in vitro studies which examine the effects of oxysterols upon cell function should be judged as to cellular oxysterol content (both in terms of the levels of oxysterol and the degree of esterification) resulting from the oxysterol treatment. We present evidence that the means by which oxysterol is delivered in vitro determines whether the oxysterol content reflects what has been found in vivo. Studies identifying the specific cellular targets of oxysterol indicate that several oxysterols may be regulators of cellular lipid metabolism via control of gene transcription.