Cholesterol Oxidation Products Research Articles

Mycobacterium tuberculosis Suppresses Inflammatory Responses in Host through Its Cholesterol Metabolites.

Cholesterol is a key carbon source for Mycobacterium tuberculosis (Mtb) survival and persistence within macrophages. However, little is known about the role of cholesterol metabolism by Mtb in host-Mtb interplay. Here, we report the immune suppression mediated by Mtb's cholesterol metabolites. Conducting the cholesterol metabolic profiling and loss-of-function experiments, we show that the cholesterol oxidation products catalyzed by a thiolase FadA5 from Mtb H37Ra, 4-androstenedione (AD), and its derivant 1,4-androstenedione (ADD) inhibit the expression of pro-inflammatory cytokines and thus promote bacterial survival in bone marrow-derived macrophages (BMDMs). Our time-resolved fluorescence resonance energy transfer (TR-FRET)-based screening further identifies the nuclear receptor LXRα as the target of ADD. Activation of LXRα via ADD impedes the nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPK) signaling and reduces cholesterol accumulation in lipid rafts upon TLR4 simulation, thereby compromising the inflammatory responses. Our findings provide the evidence that Mtb could suppress the host immunity through its cholesterol metabolic enzyme and products, which are potential targets for screening novel anti-tuberculosis (TB) agents.

Immune Implications of Cholesterol-Containing Lipid Nanoparticles.

The majority of clinically approved nanoparticle-mediated therapeutics are lipid nanoparticles (LNPs), and most of these LNPs are liposomes containing cholesterol. LNP formulations significantly alter the drug pharmacokinetics (PK) due to the propensity of nanoparticles for uptake by macrophages. In addition to readily engulfing LNPs, the high expression of cholesterol hydroxylases and reactive oxygen species (ROS) in macrophages suggests that they will readily produce oxysterols from LNP-associated cholesterol. Oxysterols are a heterogeneous group of cholesterol oxidation products that have potent immune modulatory effects. Oxysterols are implicated in the pathogenesis of atherosclerosis and certain malignancies; they have also been found in commercial liposome preparations. Yet, the in vivo metabolic fate of LNP-associated cholesterol remains unclear. We review herein the mechanisms of cellular uptake, trafficking, metabolism, and immune modulation of endogenous nanometer-sized cholesterol particles (i.e., lipoproteins) that are also relevant for cholesterol-containing nanoparticles. We believe that it would be imperative to better understand the in vivo metabolic fate of LNP-associated cholesterol and the immune implications for LNP-therapeutics. We highlight critical knowledge gaps that we believe need to be addressed in order to develop safer and more efficacious lipid nanoparticle delivery systems.

Quantitative Analysis of Sterols and Oxysterols in Foods by Gas Chromatography Coupled with Mass Spectrometry

The study aimed to determine the content of sterol oxidation products (oxysterols) in selected processed food products with the use of GC-MS. It is known that an excessively high consumption of cholesterol in foods can lead to atherosclerosis and coronary heart disease and may also promote the appearance of gallstones. Cholesterol oxidation products have mutagenic, angiotoxic and cytotoxic properties and can lead to the development of atherosclerosis and promote the occurrence of some cancers. The cholesterol content in the tested products ranged from 8.72 to 2007.11 mg/100 g fat, and plant sterols were determined in 5 out of 12 tested products and their content ranged from 5.88 to 380.8 mg/100 g fat. The studies showed the presence of sterol oxidation products in each analyzed product. The total oxysterol content ranged from 0.16 to 3.95 μg/g fat in pastry products and from 0.06 to 9.72 μg/g fat in meat products. Due to the presence of sterol oxidation products in all analyzed products, their content in food products should be monitored. The presented analytical method is a proper tool for the determination of sterol oxidation products in different food matrices.

Lipidomic profiling in patients with familial hypercholesterolemia: Abnormalities in glycerolipids and oxysterols

Objectives and aimThis study aimed to identify precise biomarkers and develop targeted therapeutic strategies for preventing premature atherosclerotic cardiovascular disease in patients with familial hypercholesterolemia (FH) by investigating the quantitative and qualitative abnormalities in the metabolic network of lipids in these patients using an advanced lipidomics platform. Design & MethodsThe study population comprised 18 homozygous (HoFH), 18 heterozygous (HeFH) FH patients, and 20 healthy controls. Cholesterol oxidation products (oxysterol, COPs) and main lipid classes were determined using gas chromatography–mass spectrometry. Results were expressed as percentages of total fat matter for lipid classes and percentages of total COPs for oxysterols. The principal component analysis (PCA) was also carried out, to highlight the correlation between studied parameters and groups investigated. ResultsPatients (both HoFH and HeFH) showed lower content of free fatty acids (FFAs) and greater values of triacylglycerols (TAGs) in comparison to controls. HoFH showed lower monoacylglycerols (P<0.01) and higher free cholesterol (FC) (P<0.05) when compared to HeFH and controls. The total content of COPs ranged from 1.96 to 4.25 mg/dL, from 2.27 to 4.05 mg/dL, and from 0.79 to 4.12 mg/dL in healthy controls, HoFH and HeFH groups, respectively, with no significant differences between patients and controls. In general, the 7α-hydroxycholesterol (7α-HC) was greater than other COPs. However, no significant differences were found between the three studied groups. Moreover, an opposite trend was observed between 7α-HC and 7-ketocholesterol (7-KC). Additionally, when PCA was carried out, the first two PCs explained 92.13 % of the total variance, of which the PC1 describes 53.94 % of variance mainly correlated to TAGs, diacylglycerols (DAGs), and 7-KC. On the other hand, the PC2 was correlated primarily for FFAs, FC and esterified sterols (E-STE). ConclusionsIn conclusion, abnormal levels of TAGs, DAGs and 7-KC were associated with HeFH while HoFH was associated with the abnormal amount of E-STE.

Effect of pullulan active packaging, incorporated with silver nanoparticles, on cholesterol oxidation product concentrations in boiler meat during storage

Effect of pullulan active packaging, incorporated with silver nanoparticles, on cholesterol oxidation product concentrations in boiler meat during storage

7-Ketocholesterol promotes cholesterol uptake and inflammation in macrophage: Potential mechanisms of dietary COP in atherosclerosis promotion

This study investigated the effects and mechanisms of 7-ketocholesterol in promoting macrophage foaming and inflammation. Single-cell RNA sequencing showed that dietary cholesterol oxidation products increased the inflammatory macrophage and Trem2high macrophage numbers in the atherosclerotic aorta of ApoE−/− mice. Enrichment analysis demonstrated activation of inflammation-related pathways (NF-κB pathway and NLRP3 inflammasome) in inflammatory macrophages and cholesterol metabolism-related pathways (LDLR and ABCG1) in Trem2high macrophages. An oxidized-LDL-treated macrophage model was employed to verify the effects and mechanisms of 7-KC on macrophage inflammation and foam cell formation. 7-KC promoted the inflammation and M1 polarization of macrophage in association with the activations of the NF-κB pathway and NLRP3 inflammasome. Furthermore, 7-KC-mediated excessive cholesterol accumulation was attributed to enhanced cholesterol uptake rather than inhibition of cholesterol efflux. Consequently, LDLR expression was up-regulated by 7-KC, while no significant effect on ABCG1 expression was observed.

Influence of salt types and honey addition on physicochemical properties, cholesterol oxidation products, microbial profile and sensory attributes of sun-dried beef jerky

Influence of salt types and honey addition on physicochemical properties, cholesterol oxidation products, microbial profile and sensory attributes of sun-dried beef jerky

Effects of Phenols from Olive Vegetation Water on Mutagenicity and Genotoxicity of Stored-Cooked Beef Patties.

This explorative study aimed to assess the mutagenicity and genotoxicity of stored-cooked beef patties formulated with and without phenols (7.00 mg of phenols/80-g patty) extracted from olive vegetation water (OVW), as related to the formation of cholesterol oxidation products (COPs) and heterocyclic amines (HCAs). The patties were packaged in a modified atmosphere, sampled during cold storage (4 °C) for 9 days, and grilled at 200 °C. The genotoxicity was evaluated by the Comet assay. The patty extract was found to be genotoxic on primary peripheral blood mononuclear cells (PBMCs), while no mutagenicity was detected. The addition of OVW phenols significantly decreased the genotoxicity of the patty extract and reduced the total COPs content in stored-cooked patties (4.59 times lower than control); however, it did not affect the content of total HCAs (31.51-36.31 ng/patty) and the revertants' number. Therefore, these results demonstrate that the OVW phenols were able to counteract the formation of genotoxic compounds in stored-cooked beef patties.

Cholesterol and Its Oxidation Derivatives Content in Market Dairy Products.

Cholesterol oxidation products (COPs) are contaminants of food of animal origin. Increased levels of these compounds in the human body are associated with an increased risk of many non-communicable diseases. Dairy products are mentioned among the main sources of these compounds in the diet. The objective of this study was to evaluate the contents of cholesterol and its oxidized derivatives in eleven groups of dairy products, willingly consumed in European countries. The levels of COPs were determined by applying the GC-TOF/MS method. In the tested products, cholesterol and its oxidation derivatives, such as 7-ketocholesterol, 7α-hydroxycholesterol, 7β-hydroxycholesterol, 5,6β-epoxycholesterol and 5,6α-epoxycholesterol, were determined. The studied dairy products differed in their contents and profiles of oxysterols. The highest contents of COPs were found in cheese with internal mold (13.8 ± 2.5 mg kg-1) and Cheddar (11.7 ± 3.5 mg kg-1), while the lowest levels were detected in yoghurt (0.94 ± 0.30 mg kg-1) and kefir (0.57 ± 0.11 mg kg-1). 7-ketocholesterol and 5,6β-epoxycholesterol were the dominant oxysterols. The ratio of oxidized derivatives to total cholesterol was on average 1.7%. Our results confirmed that dairy products are an important dietary source of COPs. Their levels should be monitored in dairy products to provide the best health quality.

Egg vs. Oil in the Cookbook of Plasters: Differentiation of Lipid Binders in Wall Paintings Using Gas Chromatography-Mass Spectrometry and Principal Component Analysis.

Wall paintings are integral to cultural heritage and offer rich insights into historical and religious beliefs. There exist various wall painting techniques that pose challenges in binder and pigment identification, especially in the case of egg/oil-based binders. GC-MS identification of lipidic binders relies routinely on parameters like the ratios of fatty acids within the plaster. However, the reliability of these ratios for binder identification is severely limited, as demonstrated in this manuscript. Therefore, a more reliable tool for effective differentiation between egg and oil binders based on a combination of diagnostic values, specific markers (cholesterol oxidation products), and PCA is presented in this study. Reference samples of wall paintings with egg and linseed oil binders with six different pigments were subjected to modern artificial ageing methods and subsequently analysed using two GC-MS instruments. A statistically significant difference (at a 95% confidence level) between the egg and oil binders and between the results from two GC-MS instruments was observed. These discrepancies between the results from the two GC-MS instruments are likely attributed to the heterogeneity of the samples with egg and oil binders. This study highlights the complexities in identifying wall painting binders and the need for innovative and revised analytical methods in conservation efforts.

The influence of the food matrix on the content of cholesterol and oxysterols during simulated process of digestion

AbstractThe purpose of the study was to evaluate the influence of the simulated digestion process on the content of the standard cholesterol and this sterol found in fats. Additionally, the content of cholesterol oxides formed after the thermal processing of fats and standard of cholesterol was investigated in samples after performing in vitro digestion procedure. The next step was to evaluate changes in the concentration of cholesterol and cholesterol oxidation products in all analyzed samples. On that basis, the bioaccessibility of cholesterol and cholesterol oxidation products in analyzed samples was established. Cholesterol bioaccessibility ranged from 1.05% to 28.38% in thermally processed samples, while cholesterol standard samples accounted for 7.16% and 5.00%. The bioaccessibility of cholesterol oxides found in analyzed fats and fats with 0.2% addition of cholesterol standard ranged from 5.44% to 19.20%, and only in butter heated at 180°C per 1 h, it reached 47.61%. Studies show that cholesterol present in the food matrix is better protected from degradation, and oxidation during thermal treatment than the standard of cholesterol (processed without food matrix). The results of this study confirm that the bioavailability of cholesterol and its oxides are influenced by the food matrix.Practical applications: The results of our experiment can be used for further scientific analyzes related to the process of estimating the bioavailability of cholesterol and cholesterol oxidation products, which can be found in food products.

Effects of Complete and Partial Loss of the 24S-Hydroxycholesterol-Generating Enzyme Cyp46a1 on Behavior and Hippocampal Transcription in Mouse.

Brain cholesterol metabolic products include neurosteroids and oxysterols, which play important roles in cellular physiology. In neurons, the cholesterol oxidation product, 24S-hydroxycholesterol (24S-HC), is a regulator of signaling and transcription. Here, we examined the behavioral effects of 24S-HC loss, using global and cell-selective genetic deletion of the synthetic enzyme CYP46A1. Mice that are globally deficient in CYP46A1 exhibited hypoactivity at young ages and unexpected increases in conditioned fear memory. Despite strong reductions in hippocampal 24S-HC in mice with selective loss of CYP46A1 in VGLUT1-positive cells, behavioral effects were not recapitulated in these conditional knockout mice. Global knockout produced strong, developmentally dependent transcriptional effects on select cholesterol metabolism genes. These included paradoxical changes in Liver X Receptor targets. Again, conditional knockout was insufficient to recapitulate most changes. Overall, our results highlight the complex effects of 24S-HC in an in vivo setting that are not fully predicted by known mechanisms. The results also demonstrate that the complete inhibition of enzymatic activity may be needed for a detectable, therapeutically relevant impact on gene expression and behavior.

Dietary supplementation with natural antioxidants: assessment of growth performance and meat quality in broiler chickens

Exposure to air and light lowers the meat quality of chickens, which is mainly determined by the color alteration and accumulation of detrimental products from lipid oxidation. This study tests the effects of two supplements rich in polyphenols, Oxilem (OX) and OxiGem (OG), on broiler Ross 308 performance and meat quality in comparison to a control group (C). A total of 105 one-day-old Ross 308 male chicks were allocated to 21 pens and randomly assigned to one of the three treatments. The trial lasted 42 days. Individual live weight and feed intake per pen were recorded. Proximate analysis, color, cholesterol content and cholesterol oxidation products (COPs), fatty acids (FAs), volatile aldehydes profile, and secondary oxidation products of meat FAs were determined, with analyses for detecting oxidative alterations conducted on breast burgers preserved for seven days at 4°C. Birds fed OG grew 7 g/day more than those receiving OX, reaching a higher final weight. After slaughtering, meat from the OX group had a higher yellow index compared to C. After seven days of air and light exposure, the influence on the color parameters of the OG and OX burgers was significantly less pronounced than that of C. Secondary oxidation products of the FAs of the burgers were not significantly affected by the diet regimens. In addition, OX and OG burgers exhibited lower amounts of volatile aldehydes, triol and COPs. These results confirm the effectiveness of OX and OG supplementation against lipid oxidation at the inclusion level used in this trial.

Cholesterol is more readily oxidized than phospholipid linoleates in cell membranes to produce cholesterol hydroperoxides

Cholesterol is an essential component of cell membranes and serves as an important precursor of steroidal hormones and bile acids, but elevated levels of cholesterol and its oxidation products have been accepted as a risk factor for maintenance of health. The free and ester forms of cholesterol and fatty acids are the two major biological lipids. The aim of this hypothesis paper is to address the long-standing dogma that cholesterol is less susceptible to free radical peroxidation than polyunsaturated fatty acids (PUFAs). It has been observed that cholesterol is peroxidized much slower than PUFAs in plasma but that, contrary to expectations from chemical reactivity toward peroxyl radicals, cholesterol appears to be more readily autoxidized than linoleates in cell membranes. The levels of oxidation products of cholesterol and linoleates observed in humans support this notion. It is speculated that this discrepancy is ascribed to the fact that cholesterol and phospholipids bearing PUFAs are localized apart in raft and non-raft domains of cell membranes respectively and that the antioxidant vitamin E distributed predominantly in the non-raft domains cannot suppress the oxidation of cholesterol lying in raft domains which are relatively deficient in antioxidant.

Effect of plasma-activated water (PAW) soaking on the lipid oxidation of sardine (Sardina pilchardus) fillets

The efficacy of plasma-activated water (PAW) as a chemical-free and environmentally friendly preservative has been documented for a variety of foods, but the onset of lipid oxidation induced by plasma-reactive species has been less extensively studied. In this work, global indices (peroxide value, UV specific absorbance) and direct analytical determinations of volatile and non-volatile oxidation products were performed on sardine lipids extracted from fish fillets immersed in PAW (treatments) and distilled water (controls) for 10–30 min. Evidence of PAW-induced lipid oxidation was provided by higher UV specific absorbances and higher levels of C5-C9 secondary volatile oxidation products in the treated samples. However, the degree of fatty acid oxidation was not sufficient to cause a significant reduction in nutritionally valuable eicosapentaenoic acid and docosahexaenoic acid. Twelve cholesterol oxidation products (COPs) were identified in the sardine lipids, but no significant differences in total COPs content were found between PAW processed and control samples.

Impact of Oxysterols in Age-Related Disorders and Strategies to Alleviate Adverse Effects.

Oxysterols or cholesterol oxidation products are a class of molecules with the sterol moiety, derived from oxidative reaction of cholesterol through enzymatic and non-enzymatic processes. They are widely reported in animal-origin foods and prove significant involvement in the regulation of cholesterol homeostasis, lipid transport, cellular signaling, and other physiological processes. Reports of oxysterol-mediated cytotoxicity are in abundance and thus consequently implicated in several age-related and lifestyle disorders such as cardiovascular diseases, bone disorders, pancreatic disorders, age-related macular degeneration, cataract, neurodegenerative disorders such as Alzheimer's and Parkinson's disease, and some types of cancers. In this chapter, we attempt to review a selection of physiologically relevant oxysterols, with a focus on their formation, properties, and roles in health and disease, while also delving into thepotential of natural and synthetic molecules along with bacterial enzymes for mitigating oxysterol-mediated cell damage.

Cholesterol Oxidation Products: Potential Adverse Effect and Prevention of Their Production in Foods.

Cholesterol oxidation products (COPs) are a group of substances formed during food processing. COPs in diet is a health concern because they may affect human health in association with the risk of various diseases including atherosclerosis, Alzheimer's disease, age-related macular degeneration, diabetes, and chronic gastrointestinal inflammatory colitis. Production of COPs in foods can be affected by many factors such as temperature, pH, light, oxygen, water, carbohydrates, fatty acids, proteins, and metal cations. The key issue is preventing its generation in foods. Some COPs can also be produced in vivo by both nonenzymatic and enzymatic-catalyzed oxidation reactions. Currently, a number of natural antioxidants such as catechins, flavonoids, and other polyphenols have been proven to inhibit the generation of COPs. In addition, measures taken during food processing can also minimize the production of COPs, such as the Maillard reaction and marinating food with plant polyphenol-rich seasonings. In conclusion, a comprehensive approach encompassing the suppression on COPs generation and implementation of processing measures is imperative to safeguard human health against the production of COPs in the food chain.

Determination of cholesterol oxidation products in cheese under photo-oxidative stress using QuEChERS and LC–MS

Determination of cholesterol oxidation products in cheese under photo-oxidative stress using QuEChERS and LC–MS

Water thermodynamics and lipid oxidation in stored whey butter

Whey butter is the result of the rational use of the whey component, which is cream whey. It is an alternative to milk cream butter. The aim of the presented study was to analyze the effect of storage conditions on water thermodynamics and cholesterol oxidation products as reliable markers of quality and safety. After 4 mo of storage, the water loss (at 3°C and 13°C) and water activity in whey butter (only at 13°C) were reduced. Three-factorial ANOVA showed that the value of water activity was independent of the type of butter in interaction with the storage temperature. The duration of the translational movement of water molecules from the inside of whey butter was definitely longer than in butter and shortened with storage time. This was in contrast to butter. For whey butter stored at 13°C, the kinetics of the movement of water molecules was at the highest speed. In the case of whey butter and butter, the higher storage temperature almost doubled the gloss. Increasing the temperature to 13°C resulted in different yellowness index, chroma, and browning index between whey butter and butter. There were no statistically significant differences in the percentage of fatty acids and triacylglycerols in whey butter and milk cream butter during storage. In whey butter, compared with butter, the cholesterol content was higher, but the amount of cholesterol oxidation products was smaller. However, in whey butter, these amounts increased significantly. The presence of epoxides and their transformation products (i.e., triol cholesterol) was found in storage whey butter.

OR09-06 The Cholesterol Oxidation Product 7-Ketosterol Reduces Progesterone Production By Human Cytotrophoblast Cells In A Sex Dimorphic Manner

Abstract Disclosure: E. Ticiani: None. N. Pascuali: None. P. Danos: None. C. Murga-Zamalloa: None. I. Buhimschi: None. A. Veiga-Lopez: None. Many pregnancy complications including recurrent miscarriage and preterm birth are strongly associated with placental dysfunction and heightened inflammation. Diet-derived cholesterol, especially via consumption of fast foods that have undergone thermal processing or long-term storage, is highly susceptible to oxidation which results in cholesterol oxidation products, known as oxysterols. Oxysterols are known drivers of inflammation and have been implicated in chronic diseases, including atherosclerosis and neurodegeneration. We hypothesized that the prototype oxysterol 7-ketosterol (7-KT) induces reduced steroid synthesis and/or secretion in human placental cells associated with a pro-inflammatory response. To test this hypothesis, we isolated human primary cytotrophoblast cells (hCTB) from healthy term pregnancies with singleton female fetuses (n=4) and exposed them to 7-KT (2.5 µg/ml) or vehicle control (C; 0.1% DMSO) for 96h. Cells were subjected to RNA sequencing using Illumina TruSeq (p&amp;lt;0.05, FDR &amp;lt;0.05 and log2 fold change &amp;gt;1). Pathway analysis discovered that 10 of the most down-regulated genes (CYP51A1, MSMO1, IDI1, HMGCS1, HMGCR, ACAT2, DDX31, DHCR7, SREBF2, NLRP7) were associated with lipid metabolism. Among them, sterol regulatory element binding transcription factor 2 (SREBF2), is a known activator of cholesterol synthesis. Using female (n=4) and male hCTB (n=4), we further evaluated sex specific effects of 7-KT after 96h of exposure using RT-qPCR. We confirmed that 7-KT reduced the expression of SREBF2 in female and in male hCTB, as well as of genes responsible for cholesterol influx (LDLR) and synthesis (HMGCR and MVK), but not of the cholesterol efflux gene ABCA1. Similar gene expression patterns were observed in JEG-3 cells exposed to 7-KT, a choriocarcinoma cell line that retains the ability to synthetize progesterone. This was coupled with a ∼50% reduction in intracellular cholesterol in JEG-3 cells exposed to 7-KT. Considering that cholesterol is the precursor for progesterone, we assessed progesterone secretion in JEG-3 and in male and female-derived hCTBs cells by ELISA. 7-KT reduced progesterone secretion by JEG-3 and female hCTB by ∼40% while male hCTB were not affected. Additionally, a short exposure (24h) to 7-KT increased the expression of pro-inflammatory genes (IL1α, IL6 and TNFα) in female, but not male hCTB. Altogether, our results demonstrate that the oxysterol 7-KT induces early pro-inflammatory gene expression, followed by a reduction in cholesterol metabolism, lower intracellular cholesterol, and progesterone secretion. Future studies should further investigate the mechanism by which 7-KT drives sex-specific changes in placental cells, and the impact of excess oxysterols on pregnancy outcomes. Presentation: Friday, June 16, 2023