Effects of carotenoids on mitochondrial dysfunction.

Oxidative stress, an imbalance between pro-oxidant and antioxidant status, favouring the pro-oxidant state is a result of increased production of reactive oxygen species (ROS) or inadequate antioxidant protection. ROS are produced through several mechanisms in cells including during mitochondrial oxidative phosphorylation. Increased mitochondrial-derived ROS are associated with mitochondrial dysfunction, an early event in age-related diseases such as Alzheimer's diseases (ADs) and in metabolic disorders including diabetes. AD post-mortem investigations of affected brain regions have shown the accumulation of oxidative damage to macromolecules, and oxidative stress has been considered an important contributor to disease pathology. An increase in oxidative stress, which leads to increased levels of superoxide, hydrogen peroxide and other ROS in a potentially vicious cycle is both causative and a consequence of mitochondrial dysfunction. Mitochondrial dysfunction may be ameliorated by molecules with antioxidant capacities that accumulate in mitochondria such as carotenoids. However, the role of carotenoids in mitigating mitochondrial dysfunction is not fully understood. A better understanding of the role of antioxidants in mitochondrial function is a promising lead towards the development of novel and effective treatment strategies for age-related diseases. This review evaluates and summarises some of the latest developments and insights into the effects of carotenoids on mitochondrial dysfunction with a focus on the antioxidant properties of carotenoids. The mitochondria-protective role of carotenoids may be key in therapeutic strategies and targeting the mitochondria ROS is emerging in drug development for age-related diseases.

Oxidative stress links periodontal inflammation and renal function.

AIMS: Patients with chronic kidney disease (CKD) are also susceptible to periodontitis. The causal link between periodontitis and CKD may be mediated via systemic inflammation/oxidative stress. Using structural equation modelling (SEM), this cross-sectional study aimed to explore the causal relationship between periodontal inflammation (PI) and renal function. MATERIALS AND METHODS: Baseline data on 770 patients with stage 3-5 (pre-dialysis) CKD from an ongoing cohort study were used. Detailed, bioclinical data on PI and renal function, as well as potential confounders and mediators of the relationship between the two, were collected. SEMs of increasing complexity were created to test the causal assumption that PI affects renal function and vice versa. RESULTS: Structural equation modelling confirmed the assumption that PI and renal function are causally linked, mediated by systemic oxidative stress. The magnitude of this effect was such that a 10% increase in PI resulted in a 3.0% decrease in renal function and a 10% decrease in renal function resulted in a 25% increase in PI. CONCLUSIONS: Periodontal inflammation represents an occult source of oxidative stress in patients with CKD. Further clinical studies are needed to confirm whether periodontal therapy, as a non-pharmacological approach to reducing systemic inflammatory/oxidative stress burden, can improve outcomes in CKD.

Hypercholesterolaemia-induced oxidative stress at the blood-brain barrier.

Blood cholesterol levels are not consistently elevated in subjects with age-related cognitive decline, although epidemiological studies suggest that Alzheimer's disease and cardiovascular diseases share common risk factors. These include the presence of an unusual genetic variant, the APOE4 (apolipoprotein E4) allele, which modulates LDL (low-density lipoproteins) metabolism, increases free radical formation and reduces plasma antioxidant concentrations. Together, these risk factors support a mechanism for increased LDL circulation time and free radical modification of LDL. Plasma oxycholesterols, hydroxylated metabolites of cholesterol, are carried by oxidized LDL, and elevated lipids in mid-life are associated with increased long-term risk of dementia. Although brain cholesterol metabolism is segregated from the systemic circulation, during oxidative stress, plasma oxycholesterols could have damaging effects on BBB (blood-brain barrier) function and consequently on neuronal cells. Cholesterol-lowering drugs such as statins may prevent the modifications to LDL in mid-life and might show beneficial effects in later life.

Micronutrients, Frailty, and Cognitive Impairment: Design and Preliminary Results from the CogLife 2.0 Study.

Background: Among preventive strategies against dementia, nutrition is considered a powerful one and the recently established "nutritional cognitive neuroscience of aging" is a highly active research field. Objective: The present study was designed to deeply characterize older adults across the continuum from cognitive integrity to mild cognitive impairment (MCI) and better elucidate the prognostic role of lipophilic micronutrients within their lipidomic signature. Methods: 123 participants older than 65 years across the continuum from cognitive integrity to MCI were included [49 with subjective cognitive impairment, 29 women, 72.5±5.4 years, 26 MCI, 9 women, 74.5±5.8 years and 50 without cognitive impairment, 21 women, 70.8±4.3 years]. All participants underwent neuropsychological and nutritional examination as well as comprehensive geriatric assessment with calculation of the Multidimensional Prognostic Index (MPI) as a proxy of frailty and biological age and blood withdrawal for the analyses of lipophilic micronutrients, metabolomics and oxylipidomics. One year after the evaluation, same tests are ongoing. Results: After adjustment for age, sex, daily fruit and vegetable intake and cholesterol, we found a significant positive correlation between lutein and the number of correct words in category fluency (p = 0.016). Conclusions: This result supports the importance of carotenoids as robust biomarkers of cognitive performance independent of the nutritional status and frailty of the participants, as the entire present study collective was robust (MPI 0-0.33). The complete analyses of the metabolome and the oxylipidome will hopefully shed light on the metabolic and prognostic signature of cognitive decline in the rapidly growing population at risk of frailty.

Cholesterol homeostasis in hair follicle keratinocytes is disrupted by impaired ABCA5 activity.

The importance of cholesterol in hair follicle biology is underscored by its links to the pathogenesis of alopecias and hair growth disorders. Reports have associated defects in ABCA5, a membrane transporter, with altered keratinocyte cholesterol distribution in individuals with a form of congenital hypertrichosis, yet the biological basis for this defect in hair growth remains unknown. This study aimed to determine the impact of altered ABCA5 activity on hair follicle keratinocyte behaviour. Primary keratinocytes isolated from the outer root sheath of plucked human hair follicles were utilised as a relevant cell model. Following exogenous cholesterol loading, an increase in ABCA5 co-localisation to intracellular organelles was seen. Knockdown of ABCA5 revealed a dysregulation in cholesterol homeostasis, with LXR agonism leading to partial restoration of the homeostatic response. Filipin staining and live BODIPY cholesterol immunofluorescence microscopy revealed a reduction in endo-lysosomal cholesterol following ABCA5 knockdown. Analysis of oxysterols showed a significant increase in the fold change of 25-hydroxycholesterol and 7-ß-hydroxycholesterol following cholesterol loading in ORS keratinocytes, after ABCA5 knockdown. These data suggest a role for ABCA5 in the intracellular compartmentalisation of free cholesterol in primary hair follicle keratinocytes. The loss of normal homeostatic response, following the delivery of excess cholesterol after ABCA5 knockdown, suggests an impact on LXR-mediated transcriptional activity. The loss of ABCA5 in the hair follicle could lead to impaired endo-lysosomal cholesterol transport, impacting pathways known to influence hair growth. This avenue warrants further investigation.

Antioxidant Micronutrients and Oxidative Stress Biomarkers.

Chronic inflammatory diseases are the major causes of mortality in humans and recent research has improved our understanding of the major impact of lifestyle factors upon inflammatory diseases and conditions. One of the most influential of these is nutrition, which may drive both pro-inflammatory as well as anti-inflammatory cascades at molecular and cellular levels. There are a variety of model systems that may be employed to investigate the impact of micronutrients and macronutrients upon inflammatory pathways, many of which operate through oxidative stress, either at the level of controlling the redox state of the cell and downstream redox-regulated gene transcription factors, and other acting as free radical generating or scavenging agents. This chapter focuses upon biological sample preparation prior to assay and details methods for analyzing certain antioxidant micronutrients and biomarkers of oxidative stress.

TNF-α-Mediated Endothelial Cell Apoptosis Is Rescued by Hydrogen Sulfide.

Endothelial dysfunction is implicated in the development and aggravation of cardiovascular complications. Among the endothelium-released vasoactive factors, hydrogen sulfide (H2S) has been investigated for its beneficial effects on the vasculature through anti-inflammatory and redox-modulating regulatory mechanisms. Reduced H2S bioavailability is reported in chronic diseases such as cardiovascular disease, diabetes, atherosclerosis and preeclampsia, suggesting the value of investigating mechanisms, by which H2S acts as a vasoprotective gasotransmitter. We explored whether the protective effects of H2S were linked to the mitochondrial health of endothelial cells and the mechanisms by which H2S rescues apoptosis. Here, we demonstrate that endothelial dysfunction induced by TNF-α increased endothelial oxidative stress and induced apoptosis via mitochondrial cytochrome c release and caspase activation over 24 h. TNF-α also affected mitochondrial morphology and altered the mitochondrial network. Post-treatment with the slow-releasing H2S donor, GYY4137, alleviated oxidising redox state, decreased pro-caspase 3 activity, and prevented endothelial apoptosis caused by TNF-α alone. In addition, exogenous GYY4137 enhanced S-sulfhydration of pro-caspase 3 and improved mitochondrial health in TNF-α exposed cells. These data provide new insights into molecular mechanisms for cytoprotective effects of H2S via the mitochondrial-driven pathway.

Tspan6 stimulates the chemoattractive potential of breast cancer cells for B cells in an EV- and LXR-dependent manner.

The immune microenvironment in breast cancer (BCa) is controlled by a complex network of communication between various cell types. Here, we find that recruitment of B lymphocytes to BCa tissues is controlled via mechanisms associated with cancer cell-derived extracellular vesicles (CCD-EVs). Gene expression profiling identifies the Liver X receptor (LXR)-dependent transcriptional network as a key pathway that controls both CCD-EVs-induced migration of B cells and accumulation of B cells in BCa tissues. The increased accumulation oxysterol ligands for LXR (i.e., 25-hydroxycholesterol and 27-hydroxycholesterol) in CCD-EVs is regulated by the tetraspanin 6 (Tspan6). Tspan6 stimulates the chemoattractive potential of BCa cells for B cells in an EV- and LXR-dependent manner. These results demonstrate that tetraspanins control intercellular trafficking of oxysterols via CCD-EVs. Furthermore, tetraspanin-dependent changes in the oxysterol composition of CCD-EVs and the LXR signaling axis play a key role in specific changes in the tumor immune microenvironment.

Oxysterols and Oxysterol Sulfates in Alzheimer's Disease Brain and Cerebrospinal Fluid.

BACKGROUND: Brain cholesterol levels are tightly regulated but increasing evidence indicates that cholesterol metabolism may drive Alzheimer's disease (AD)-associated pathological changes. Recent advances in understanding of mitochondrial dysfunction in AD brain have presented a vital role played by mitochondria in oxysterol biosynthesis and their involvement in pathophysiology. Oxysterol accumulation in brain is controlled by various enzymatic pathways including sulfation. While research into oxysterol is under the areas of active investigation, there is less evidence for oxysterol sulfate levels in human brain. OBJECTIVE: This study investigates the hypothesis that AD brain oxysterol detoxification via sulfation is impaired in later stages of disease resulting in oxysterol accumulation. METHODS: Lipids were extracted from postmortem frozen brain tissue and cerebrospinal (CSF) from late- (Braak stage III-IV) and early- (Braak stage I-II) stage AD patients. Samples were spiked with internal standards prior to lipid extraction. Oxysterols were enriched with a two-step solid phase extraction using a polymeric SPE column and further separation was achieved by LC-MS/MS. RESULTS: Oxysterols, 26-hydroxycholesterol (26-OHC), 25-hydroxycholesterol (25-OHC), and 7-oxycholesterol levels were higher in brain tissue and mitochondria extracted from late-stage AD brain tissue except for 24S-hydroxycholesterol, which was decreased in late AD. However, oxysterol sulfates are significantly lower in the AD frontal cortex. Oxysterols, 25-OHC, and 7-oxocholesterol was higher is CSF but 26-OHC and oxysterol sulfate levels were not changed. CONCLUSION: Our results show oxysterol metabolism is altered in AD brain mitochondria, favoring synthesis of 26-OHC, 25-OHC, and 7-oxocholesterol, and this may influence brain mitochondrial function and acceleration of the disease.

Paternal low protein diet perturbs inter-generational metabolic homeostasis in a tissue-specific manner in mice.

The underlying mechanisms driving paternally-programmed metabolic disease in offspring remain poorly defined. We fed male C57BL/6 mice either a control normal protein diet (NPD; 18% protein) or an isocaloric low protein diet (LPD; 9% protein) for a minimum of 8 weeks. Using artificial insemination, in combination with vasectomised male mating, we generated offspring using either NPD or LPD sperm but in the presence of NPD or LPD seminal plasma. Offspring from either LPD sperm or seminal fluid display elevated body weight and tissue dyslipidaemia from just 3 weeks of age. These changes become more pronounced in adulthood, occurring in conjunction with altered hepatic metabolic and inflammatory pathway gene expression. Second generation offspring also display differential tissue lipid abundance, with profiles similar to those of first generation adults. These findings demonstrate that offspring metabolic homeostasis is perturbed in response to a suboptimal paternal diet with the effects still evident within a second generation.

Activation of the neutrophil respiratory burst by plasma from periodontitis patients is mediated by pro-inflammatory cytokines.

AIM: To determine the effect of periodontitis patients' plasma on the neutrophil oxidative burst and the role of albumin, immunoglobulins (Igs) and cytokines. MATERIALS AND METHODS: Plasma was collected from chronic periodontitis patients (n=11) and periodontally healthy controls (n=11) and used with/without depletion of albumin and Ig or antibody neutralization of IL-8, GM-CSF or IFN-α to prime/stimulate peripheral blood neutrophils, isolated from healthy volunteers. The respiratory burst was measured by lucigenin-dependent chemiluminescence. Plasma cytokine levels were determined by ELISA. RESULTS: Plasmas from patients were significantly more effective in both directly stimulating neutrophil superoxide production and priming for subsequent formyl-met-leu-phe (fMLP)-stimulated superoxide production than plasmas from healthy controls (p<0.05). This difference was maintained after depletion of albumin and Ig. Plasma from patients contained higher mean levels of IL-8, GM-CSF and IFN-α. Individual neutralizing antibodies against IL-8, GM-CSF or IFN-α inhibited the direct stimulatory effect of patients' plasma, whereas the ability to prime for fMLP-stimulated superoxide production was only inhibited by neutralization of IFN-α. The stimulating and priming effects of control plasma were unaffected by antibody neutralization. CONCLUSIONS: This study demonstrates that plasma cytokines may have a role in inducing the hyperactive (IL-8, GM-CSF, IFN-α) and hyper-reactive (IFN-α) neutrophil phenotype seen in periodontitis patients.

Current and Future Directions for Targeting Lipoxin A4 in Alzheimer's Disease.

Neuroinflammation has been implicated in Alzheimer's disease onset and progression. Chronic neuroinflammation is initiated by amyloid-ß-activated microglial cells that secrete immuno-modulatory molecules within the brain and into the vasculature. Inflammation is normally self-limiting and actively resolves by "switching off" the generation of pro-inflammatory mediators and by non-phlogistic clearance of spent cells and their debris to restore tissue homeostasis. Deficits in these anti-inflammatory/pro-resolution pathways may predispose to the development of chronic inflammation. The synthesis of endogenous lipid mediators from arachidonic acid, lipoxins via cyclooxygenase 2 and lipoxygenases, and conversion of exogenous polyunsaturated fatty acids, namely docosahexaenoic acid and eicosapentaenoic acid, to resolvins contributes to effective, timely resolution of acute inflammation. Work by Xiuzhe et al., 2020 in the Journal of Alzheimer's Disease reported that plasma level of LXA4 is related to cognitive status in ischemic stroke patients suggesting that decreased LXA4 may be a potential risk factor for post post-stroke cognitive impairment. As evident by recent clinical trials and development of drug analogues, there is recent drive to search for lipoxin analogues as therapeutics for inflammatory diseases. Understanding how bioactive lipid signaling is involved in resolution will increase our understanding of controlling inflammation and may facilitate the discovery of new classes of therapeutic pro-resolution agents for evaluation in AD prevention studies.

Cholesterol and oxysterol sulfates: Pathophysiological roles and analytical challenges.

Cholesterol and oxysterol sulfates are important regulators of lipid metabolism, inflammation, cell apoptosis, and cell survival. Among the sulfate-based lipids, cholesterol sulfate (CS) is the most studied lipid both quantitatively and functionally. Despite the importance, very few studies have analysed and linked the actions of oxysterol sulfates to their physiological and pathophysiological roles. Overexpression of sulfotransferases confirmed the formation of a range of oxysterol sulfates and their antagonistic effects on liver X receptors (LXRs) prompting further investigations how are the changes to oxysterol/oxysterol sulfate homeostasis can contribute to LXR activity in the physiological milieu. Here, we aim to bring together for novel roles of oxysterol sulfates, the available techniques and the challenges associated with their analysis. Understanding the oxysterol/oxysterol sulfate levels and their pathophysiological mechanisms could lead to new therapeutic targets for metabolic diseases. LINKED ARTICLES: This article is part of a themed issue on Oxysterols, Lifelong Health and Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.16/issuetoc.

Microvascular function and oxidative stress in adult individuals with early onset of cardiovascular disease.

The current study aims to investigate retinal vascular function and its relationship with systemic anti-oxidative defence capacity in normal individuals versus those with early hypertensive changes according to the current ESC/ESH guidelines. Retinal microvascular function was assessed in 201 participants by means of dynamic retinal vessel analysis. Blood pressure, lipid panel, oxidized (GSH) & reduced glutathione (GSSG) were also evaluated for each participant. Individuals classed as grade 1 hypertension demonstrated higher retinal arterial baseline diameter fluctuation (p = 0.0012), maximum dilation percentage (p = 0.0007), time to maximum constriction (p = 0.0003) and lower arterial constriction slope (p = 0.0131). Individuals classed as high normal and grade 1 hypertension also demonstrated higher time to maximum dilation than individuals classed as optimal or normal. GSH levels correlated negatively with SBP, DBP and MBP values in all participants (p = 0.0010; p = 0.0350 and p = 0.0050) as well as with MBP values in high normal and grade 1 hypertension (p = 0.0290). The levels of GSSG correlated positively with SBP, DBP and MBP values in all participants (p = 0.0410; p = 0.0330 and, p = 0.0220). Our results point to the fact that microvascular alterations can be identifiable at BP values still considered within normal values and go in parallel with the changes observed in the level of oxidative stress.

Distribution of plasma oxidised phosphatidylcholines in chronic kidney disease and periodontitis as a co-morbidity.

Individuals with chronic kidney disease (CKD) and periodontitis as a co-morbidity have a higher mortality rate than individuals with CKD and no periodontitis. The inflammatory burden associated with both diseases contributes to an increased risk of cardiovascular and all-cause mortality. We previously demonstrated that periodontitis is associated with increasing circulating markers of inflammation and oxidative stress. We propose that inflammatory oxidised phosphocholines may contribute to the increased risk of cardiovascular disease in patients with CKD. However, the analysis of oxidised phospholipids has been limited by a lack of authentic standards for absolute quantification. Here, we have developed a comprehensive quantification liquid chromatography-mass spectrometry-based multiple reaction monitoring method for oxidised phospholipids (including some without available authentic species) that enables us to simultaneously measure twelve oxidised phosphatidylcholine species with high levels of sensitivity and specificity. The standard curves for commercial standards 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphatidylcholine (PGPC); 1-palmitoyl-2-(9'-oxo-nonanoyl)-sn-glycero-3-phosphatidylcholine (PONPC), 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphatidylcholine (PAzPC) and 1-palmitoyl-2-(5'-oxo-valeroyl)-sn-glycero-3-phosphatidylcholine (POVPC), were linear with a correlation coefficient greater than 0.99 for all analytes. The method is reproducible, with intra- and inter-day precision <15%, and accuracy within ±5% of nominal values for all analytes. This method has been successfully applied to investigate oxidised phosphatidylcholine in plasma from CKD patients with and without chronic periodontitis and the data that was obtained has been compared to plasma from healthy controls. Comparative analysis demonstrates altered chain fragmented phosphatidylcholine profiles in the plasma samples of patients with CKD and periodontitis as a co-morbidity compared to healthy controls.

Bioenergetic effects of hydrogen sulfide suppress soluble Flt-1 and soluble endoglin in cystathionine gamma-lyase compromised endothelial cells.

Endothelial dysfunction is a hallmark of preeclampsia, a life-threatening complication of pregnancy characterised by hypertension and elevated soluble Fms-Like Tyrosine Kinase-1 (sFlt-1). Dysregulation of hydrogen sulfide (H2S) by inhibition of cystathionine γ-lyase (CSE) increases sFlt-1 and soluble endoglin (sEng) release. We explored whether compromise in CSE/H2S pathway is linked to dysregulation of the mitochondrial bioenergetics and oxidative status. We investigated whether these effects were linked to CSE-induced sFlt-1 and sEng production in endothelial cells. Here, we demonstrate that CSE/H2S pathway sustain endothelial mitochondrial bioenergetics and loss of CSE increases the production of mitochondrial-specific superoxide. As a compensatory effect, low CSE environment enhances the reliance on glycolysis. The mitochondrial-targeted H2S donor, AP39, suppressed the antiangiogenic response and restored the mitochondrial bioenergetics in endothelial cells. AP39 revealed that upregulation of sFlt-1, but not sEng, is independent of the mitochondrial H2S metabolising enzyme, SQR. These data provide new insights into the molecular mechanisms for antiangiogenic upregulation in a mitochondrial-driven environment. Targeting H2S to the mitochondria may be of therapeutic benefit in the prevention of endothelial dysfunction associated with preeclampsia.

Inflammation, Lipid (Per)oxidation, and Redox Regulation.

Significance: Inflammation increases during the aging process. It is linked to mitochondrial dysfunction and increased reactive oxygen species (ROS) production. Mitochondrial macromolecules are critical targets of oxidative damage; they contribute to respiratory uncoupling with increased ROS production, redox stress, and a cycle of senescence, cytokine production, and impaired oxidative phosphorylation. Targeting the formation or accumulation of oxidized biomolecules, particularly oxidized lipids, in immune cells and mitochondria could be beneficial for age-related inflammation and comorbidities. Recent Advances: Inflammation is central to age-related decline in health and exhibits a complex relationship with mitochondrial redox state and metabolic function. Improvements in mass spectrometric methods have led to the identification of families of oxidized phospholipids (OxPLs), cholesterols, and fatty acids that increase during inflammation and which modulate nuclear factor erythroid 2-related factor 2 (Nrf2), peroxisome proliferator-activated receptor gamma (PPARγ), activator protein 1 (AP1), and NF-κB redox-sensitive transcription factor activity. Critical Issues: The kinetic and spatial resolution of the modified lipidome has profound and sometimes opposing effects on inflammation, promoting initiation at high concentration and resolution at low concentration of OxPLs. Future Directions: There is an emerging opportunity to prevent or delay age-related inflammation and vascular comorbidity through a resolving (oxy)lipidome that is dependent on improving mitochondrial quality control and restoring redox homeostasis.

Partial Mitigation of Oxidized Phospholipid-Mediated Mitochondrial Dysfunction in Neuronal Cells by Oxocarotenoids.

Mitochondria are important (patho)physiological sources of reactive oxygen species (ROS) that mediate mitochondrial dysfunction and phospholipid oxidation; an increase in mitochondrial content of oxidized phospholipid (OxPL) associates with cell death. Previously we showed that the circulating OxPL 1-palmitoyl-2-(5'-oxo-valeroyl)-sn-glycero-3-phosphocholine (POVPC) increases in patients with Alzheimer's disease (AD), and associates with lower plasma antioxidant oxocarotenoids, zeaxanthin, and lutein. Since oxocarotenoids are metabolized in mitochondria, we propose that during AD, lower concentrations of mitochondrial zeaxanthin and lutein may result in greater phospholipid oxidation and predispose to neurodegeneration. Here, we have investigated whether non-toxic POVPC concentrations impair mitochondrial metabolism in differentiated (d)SH-SY5Y neuronal cells and whether there is any protective role for oxocarotenoids against mitochondrial dysfunction. After 24 hours, glutathione (GSH) concentration was lower in neuronal cells exposed to POVPC (1-20 µM) compared with vehicle control without loss of viability compared to control. However, mitochondrial ROS production (determined by MitoSOX oxidation) was increased by 50% only after 20 µM POVPC. Following delivery of lutein (0.1-1 µM) and zeaxanthin (0.5-5 µM) over 24 hours in vitro, oxocarotenoid recovery from dSH-SY5Y cells was > 50%. Co-incubation with oxocarotenoids prevented loss of GSH after 1 µM but not 20 µM POVPC, whereas the increase in ROS production induced by 20 µM POVPC was prevented by lutein and zeaxanthin. Mitochondrial uncoupling increases and ATP production is inhibited by 20 µM but not 1 µM POVPC; carotenoids protected against uncoupling although did not restore ATP production. In summary, 20 µM POVPC induced loss of GSH and a mitochondrial bioenergetic deficit in neuronal cells that was not mitigated by oxocarotenoids.

Cerebrospinal Fluid 7-Ketocholesterol Level is Associated with Amyloid-ß42 and White Matter Microstructure in Cognitively Healthy Adults.

BACKGROUND: Abnormal cholesterol metabolism changes the neuronal membrane and may promote amyloidogenesis. Oxysterols in cerebrospinal fluid (CSF) are related to Alzheimer's disease (AD) biomarkers in mild cognitive impairment and dementia. Cholesterol turnover is important for axonal and white matter (WM) microstructure maintenance. OBJECTIVE: We aim to demonstrate that the association of oxysterols, AD biomarkers, and WM microstructure occurs early in asymptomatic individuals. METHODS: We studied the association of inter-individual variability of CSF 24-hydroxycholesterol (24-OHC), 27-hydroxycholesterol (27-OHC), 7-ketocholesterol (7-KC), 7ß-hydroxycholesterol (7ß-OHC), amyloid-ß42 (Aß42), total-tau (t-tau), phosphorylated-tau (p-tau), neurofilament (NfL), and WM microstructure using diffusion tensor imaging, generalized linear models and moderation/mediation analyses in 153 healthy adults. RESULTS: Higher 7-KC levels were related to lower Aß42, indicative of greater AD pathology (p = 0.041) .  Higher 7-KC levels were related to lower fractional anisotropy (FA) and higher mean (MD), axial (AxD), and radial (RD) diffusivity. 7-KC modulated the association between AxD and NfL in the corpus callosum splenium (B = 39.39, p = 0.017), genu (B = 68.64, p = 0.000), and fornix (B = 10.97, p = 0.000). Lower Aß42 levels were associated to lower FA and higher MD, AxD, and RD in the fornix, corpus callosum, inferior longitudinal fasciculus, and hippocampus. The association between AxD and Aß42 was moderated by 7K-C (p = 0.048). CONCLUSION: This study adds clinical evidence to support the role of 7K-C on axonal integrity and the involvement of cholesterol metabolism in the Aß42 generation process.

Sulfate-based lipids: Analysis of healthy human fluids and cell extracts.

Sulfate-based lipids (SL) have been proposed as players in inflammation, immunity and infection. In spite of the many biochemical processes linked to SL, analysis on this class of lipids has only focused on specific SL sub-classes in individual fluids or cells leaving a range of additional SL in other biological samples unaccounted for. This study describes the mass spectrometry screening of SL in lipid extracts of human fluids (saliva, plasma, urine, seminal fluid) and primary human cells (RBC, neutrophils, fibroblasts and skin epidermal) using targeted precursor ion scanning (PIS) approach. The PIS 97 mass spectra reveal a wide diversity of SL including steroid sulfates, sulfoglycolipids and other unidentified SL, as well as metabolites such as taurines, sulfated polyphenols and hypurate conjugates. Semi-quantification of SL revealed that plasma exhibited the highest content of SL whereas seminal fluid and epithelial cells contained the highest sulphur to phosphorous (S/P) ratio. The complexity of biofluids and cells sulfateome presented in this study highlight the importance of expanding the panel of synthetic sulfate-based lipid standards. Also, the heterogenous distribution of SL provides evidence for the interplay of sulfotransferases/sulfatases, opening new avenues for biomarker discovery in oral health, cardiovascular, fertility and dermatology research areas.