Levels Of 7-dehydrocholesterol Research Articles

Impact of Daily High Ergosterol Intake for 14 Weeks in Ovariectomized Rats on Cholesterol and Vitamin D3 Biosynthesis Pathways

Postmenopausal women are at a higher risk of developing dyslipidemia and osteoporosis due to estrogen deficiency, necessitating regular vitamin D supplementation and the use of cholesterol inhibitors, respectively, to prevent these conditions. Despite current treatments, alternatives are needed to address both conditions simultaneously. Ergosterol, a precursor of vitamin D2, is a fungal sterol converted to brassicasterol by 7-dehydrocholesterol reductase, a cholesterol biosynthesis enzyme that converts 7-dehydrocholesterol (a precursor of vitamin D3) into cholesterol. Our previous research demonstrated that ergosterol decreases cholesterol levels and increases 7-dehydrocholesterol levels in human HepG2 hepatoma cells. Furthermore, we reported that ergosterol increases vitamin D2 levels, inhibits the cholesterol biosynthetic pathway, and potentially promotes vitamin D3 biosynthesis in male rats fed a high-fat and high-sucrose diet. In this study, we investigated the effects of daily high ergosterol intake on cholesterol, vitamin D2, and D3 biosynthetic pathways in ovariectomized (OVX) rats using GC-MS and LC with tandem mass spectrometry. OVX rats treated with ergosterol for 14 weeks exhibited significantly decreased plasma cholesterol levels and markers of cholesterol absorption, such as the plant sterol sitosterol. Furthermore, 7-dehydrocholesterol levels increased in these rats compared to untreated OVX rats. We observed that 1α, 25-dihydroxyvitamin D3 levels slightly increased in OVX rats treated with ergosterol. Additionally, ergosterol improved bone strength and increased OVX-induced bone resorption. These results indicate that daily ergosterol intake may aid in the simultaneous prevention of dyslipidemia and osteoporosis in postmenopausal women.

Ginsenosides From Panax ginseng Improves Hepatic Lipid Metabolism Disorders in HFD-Fed Rats by Regulating Gut Microbiota and Cholesterol Metabolism Signaling Pathways.

A high-fat diet (HFD) is often associated with hepatic lipid metabolism disorders, leading to dysfunction in multiple body systems. Ginsenosides derived from Panax ginseng have been reported to possess potential effects in ameliorating lipid metabolism disorders; however, their underlying mechanisms remain insufficiently explored. This study aims to investigate the bioactivities of ginsenosides in combating lipid metabolism disorders and obesity, with a focus on their mechanisms involving the cholesterol metabolism signaling pathway and gut microbiota. Our results demonstrated that ginsenoside treatment significantly reduced overall body weight, body weight changes, liver weight, and eWAT weight, as well as alleviated hepatic steatosis and dyslipidemia in HFD-fed rats, without affecting food intake. These effects were dose-dependent. Furthermore, 16S rRNA sequencing revealed that ginsenosides significantly increased the relative abundance of Akkermansia muciniphila, Blautia, Eisenbergiella, Clostridium clusters XI, XVIII, and III, while decreasing the relative abundance of Clostridium subcluster XIVa and Dorea. In addition, ginsenoside treatment significantly regulated the expression of hepatic genes and proteins involved in the cholesterol metabolism signaling pathway (FXR, CYP7A1, CYP7B1, CYP27A1, ABCG5, ABCG8, Insig2, and Dhcr7), potentially inhibiting hepatic cholesterol biosynthesis while promoting cholesterol transport to HDL and its excretion via bile and feces. Notably, levels of 7-dehydrocholesterol (7-DHC) and 27-hydroxycholesterol (27-OHC) were reduced, while 5β,6β-epoxycholesterol (5,6β-epoxy) levels were elevated following ginsenoside treatment, indicating significant modulation of oxysterols by ginsenosides. Moreover, bile acid enterohepatic circulation was regulated through the enhancement of hepatic FXR-CYP7A1 signaling and intestinal FXR-FGF15 signaling in HFD-fed rats treated with ginsenosides, which was closely linked to gut microbiota composition. Collectively, our findings suggest that ginsenosides alleviate hepatic lipid metabolism disorders by modulating gut microbiota and the cholesterol metabolism signaling pathway in HFD-fed rats.

Inhibition of post-lanosterol biosynthesis by fentanyl: potential implications for Fetal Fentanyl Syndrome (FFS).

A recent study discovered a novel, complex developmental disability syndrome, most likely caused by maternal fentanyl use disorder. This Fetal Fentanyl Syndrome (FFS) is biochemically characterized by elevated 7-dehydrocholesterol (7-DHC) levels in neonates, raising the question if fentanyl inhibition of the dehydrocholesterol reductase 7 (DHCR7) enzyme is causal for the emergence of the pathophysiology and phenotypic features of FFS. To test this hypothesis, we undertook a series of experiments on Neuro2a cells, primary mouse neuronal and astrocytic cultures, and human dermal fibroblasts (HDFs) with DHCR7+/+ and DHCR7+/- genotype. Our results revealed that in vitro exposure to fentanyl disrupted sterol biosynthesis across all four in vitro models. The sterol biosynthesis disruption by fentanyl was complex, and encompassed the majority of post-lanosterol intermediates, including elevated 7-DHC and decreased desmosterol (DES) levels across all investigated models. The overall findings suggested that maternal fentanyl use in the context of an opioid use disorder leads to FFS in the developing fetus through a strong disruption of the whole post-lanosterol pathway that is more complex than a simple DHCR7 inhibition. In follow-up experiments we found that heterozygous DHCR7+/- HDFs were significantly more susceptible to the sterol biosynthesis inhibitory effects of fentanyl than wild-type DHCR7+/+ fibroblasts. These data suggest that DHCR7+/- heterozygosity of mother and/or developing child (and potentially other sterol biosynthesis genes), when combined with maternal fentanyl use disorder, might be a significant contributory factor to the emergence of FFS in the exposed offspring. In a broader context, we believe that evaluation of new and existing medications for their effects on sterol biosynthesis should be an essential consideration during drug safety determinations, especially in pregnancy.

Associations between lifestyle, health, and clinical characteristics and circulating oxysterols and cholesterol precursors in women diagnosed with breast cancer: a cross-sectional study

Despite increasing evidence that cholesterol precursors and oxysterols, oxidized cholesterol metabolites, play a role in numerous pathological processes and diseases including breast cancer, little is known about correlates of these sterols in women with breast cancer. In this study, 2282 women with breast cancer and blood draw post diagnosis were included and cross-sectional associations between circulating levels of 15 sterols/oxysterols and (a) lifestyle, anthropometric, reproductive characteristics, (b) comorbidities and medication use, and (c) breast cancer tumor and treatment characteristics were calculated using generalized linear models. Obesity was strongly associated with circulating levels of 7-dehydrocholesterol (DC) (body mass index ≥ 30 vs. 18.5–24.9 kg/m2: 51.7% difference) and 7-ketocholesterol (KC) (40.0% difference). After adjustment for BMI, comorbidities such as cardiovascular disease were associated with higher levels of 7-DC (26.1% difference) and lower levels of desmosterol (− 16.4% difference). Breast cancer tumor characteristics including hormone receptor status, tumor stage, and endocrine therapy were associated with lanosterol, 24-DHLan, 7b-HC, and THC (e.g., THC; tumor stage IIIa vs. I: 36.9% difference). Weaker associations were observed for lifestyle characteristics and for any of the other oxysterols. The findings of this study suggest that cholesterol precursors are strongly associated with metabolic factors, while oxysterols are associated with breast cancer tumor characteristics, warranting further investigation into the role of cholesterol precursors and oxysterols in women with breast cancer and other populations.

7-Dehydrocholesterol dictates ferroptosis sensitivity.

Ferroptosis, a form of regulated cell death that is driven by iron-dependent phospholipid peroxidation, has been implicated in multiple diseases, including cancer1-3, degenerative disorders4 and organ ischaemia-reperfusion injury (IRI)5,6. Here, using genome-wide CRISPR-Cas9 screening, we identified that the enzymes involved in distal cholesterol biosynthesis have pivotal yet opposing roles in regulating ferroptosis through dictating the level of 7-dehydrocholesterol (7-DHC)-an intermediate metabolite of distal cholesterol biosynthesis that is synthesized by sterol C5-desaturase (SC5D) and metabolized by 7-DHC reductase (DHCR7) for cholesterol synthesis. We found that the pathway components, including MSMO1, CYP51A1, EBP and SC5D, function as potential suppressors of ferroptosis, whereas DHCR7 functions as a pro-ferroptotic gene. Mechanistically, 7-DHC dictates ferroptosis surveillance by using the conjugated diene to exert its anti-phospholipid autoxidation function and shields plasma and mitochondria membranes from phospholipid autoxidation. Importantly, blocking the biosynthesis of endogenous 7-DHC by pharmacological targeting of EBP induces ferroptosis and inhibits tumour growth, whereas increasing the 7-DHC level by inhibiting DHCR7 effectively promotes cancer metastasis and attenuates the progression of kidney IRI, supporting a critical function of this axis in vivo. In conclusion, our data reveal a role of 7-DHC as a natural anti-ferroptotic metabolite and suggest that pharmacological manipulation of 7-DHC levels is a promising therapeutic strategy for cancer and IRI.

Effects of Long-Term High-Ergosterol Intake on the Cholesterol and Vitamin D Biosynthetic Pathways of Rats Fed a High-Fat and High-Sucrose Diet

Dyslipidemia is a lifestyle-related (physical inactivity or obesity) disease; therefore, dietary foods that can easily be consumed in daily life is important to prevent dyslipidemia. Ergosterol, a precursor of vitamin D2, is a fungal sterol present in the membranes of edible mushrooms and other fungi. Ergosterol is converted to brassicasterol by 7-dehydrocholesterol reductase (DHCR7), a cholesterol biosynthesis enzyme that converts 7-dehydrocholesterol (a precursor of vitamin D3) into cholesterol. Previously, we reported that ergosterol increases 7-dehydrocholesterol, decreases cholesterol levels by competitive effect of DHCR7, and reduces DHCR7 mRNA and protein levels in human HepG2 hepatoma cells. Here, we investigated the effects of long-term high ergosterol intake on the cholesterol, vitamin D2, and D3 biosynthetic pathways of rats fed a high-fat and high-sucrose (HFHS) diet using GC-MS and LC with tandem mass spectrometry. In HFHS rats, oral ergosterol administration for 14 weeks significantly decreased plasma low-density lipoprotein cholesterol, total bile acid, and cholesterol precursor (squalene and desmosterol) levels and increased 7-dehydrocholesterol levels compared to HFHS rats without ergosterol. Ergosterol, brassicasterol, and vitamin D2 were detected, cholesterol levels were slightly decreased, and levels of vitamin D3 and its metabolites were slightly increased in rats fed HFHS with ergosterol. These results showed that ergosterol increased vitamin D2 levels, inhibited the cholesterol biosynthetic pathway, and possibly promoted vitamin D3 biosynthesis in vivo. Therefore, daily ergosterol intake may aid in the prevention of dyslipidemia.

Dose-Response Effects of 7-Dehydrocholesterol Reductase Inhibitors on Sterol Profiles and Vesicular Stomatitis Virus Replication.

Cholesterol is ubiquitous in cells; it plays a critical role in membrane structure and transport as well as in intracellular trafficking processes. There are suggestions that cholesterol metabolism is linked to innate immunity with inhibitors of DHCR7, the last enzyme in the cholesterol pathway, suggested to have potential as viral therapeutics nearly a decade ago. In fact, there are a number of highly prescribed pharmaceuticals that are off-target inhibitors of DHCR7, causing increased cellular levels of 7-dehydrodesmosterol (7-DHD) and 7-dehydrocholesterol (7-DHC). We report here dose-response studies of six such inhibitors on late-stage cholesterol biosynthesis in Neuro2a cells as well as their effect on infection of vesicular stomatitis virus (VSV). Four of the test compounds are FDA-approved drugs (cariprazine, trazodone, metoprolol, and tamoxifen), one (ifenprodil) has been the object of a recent Phase 2b COVID trial, and one (AY9944) is an experimental compound that has seen extensive use as a DHCR7 inhibitor. The three FDA-approved drugs inhibit replication of a GFP-tagged VSV with efficacies that mirror their effect on DHCR7. Ifenprodil and AY9944 have complex inhibitory profiles, acting on both DHCR7 and DHCR14, while tamoxifen does not inhibit DHCR7 and is toxic to Neuro2a at concentrations where it inhibits the Δ7-Δ8 isomerase of the cholesterol pathway. VSV itself affects the sterol profile in Neuro2a cells, showing a dose-response increase of dehydrolathosterol and lathosterol, the substrates for DHCR7, with a corresponding decrease in desmosterol and cholesterol. 7-DHD and 7-DHC are orders of magnitude more vulnerable to free radical chain oxidation than other sterols as well as polyunsaturated fatty esters, and the effect of these sterols on viral infection is likely a reflection of this fact of Nature.

Effects of Psychotropic Medication on Somatic Sterol Biosynthesis of Adult Mice.

Polypharmacy is commonly used to treat psychiatric disorders. These combinations often include drugs with sterol biosynthesis inhibiting side effects, including the antipsychotic aripiprazole (ARI), and antidepressant trazodone (TRZ). As the effects of psychotropic medications are poorly understood across the various tissue types to date, we investigated the effects of ARI, TRZ, and ARI + TRZ polypharmacy on the post-lanosterol biosynthesis in three cell lines (Neuro2a, HepG2, and human dermal fibroblasts) and seven peripheral tissues of an adult mouse model. We found that both ARI and TRZ strongly interfere with the function of 7-dehydrocholesterol reductase enzyme (DHCR7) and lead to robust elevation in 7-dehydrocholesterol levels (7-DHC) and reduction in desmosterol (DES) across all cell lines and somatic tissues. ARI + TRZ co-administration resulted in summative or synergistic effects across the utilized in vitro and in vivo models. These findings suggest that at least some of the side effects of ARI and TRZ are not receptor mediated but arise from inhibiting DHCR7 enzyme activity. We propose that interference with sterol biosynthesis, particularly in the case of simultaneous utilization of medications with such side effects, can potentially interfere with functioning or development of multiple organ systems, warranting further investigation.

Isolated autism is not an indication for Smith-Lemli-Opitz syndrome biochemical testing.

To determine if there is any correlation with a clinical indication of ASD and a biochemical diagnosis of SLOS, based on historical test request and assay data. Six years (2008-2013) of clinical test requests for 7-dehydrocholesterol (7-DHC) level were classified and summarised according to indication and final test result. From the audit period, 988 valid test results from post-natal samples were identified. In plasma/serum, mean 7-DHC level was 264.7μmol/L (normal range < 2.0) for confirmed SLOS cases. No tests performed due to an isolated clinical indication of ASD or where no clinical information was supplied were associated with 7-DHC levels diagnostic for SLOS. Historical test data analysis supports the recommendation that autism/ASD as a single clinical feature is not an appropriate indication for SLOS (7-DHC) biochemical testing.

UVB exposure stimulates production of vitamin D3 in selected microalgae

There has been a rise in awareness about the low dietary intake of vitamin D worldwide. Besides being provided through the diet, vitamin D3 can be synthesized in skin when exposed to UVB light. UVB light triggers the conversion of naturally present 7-dehydrocholesterol (provitamin D3) to vitamin D3 in skin. In this study four microalgal species, Tetraselmis suecica, Dunaliella salina, Nannochloropsis oceanica and Nannochloropsis limnetica were cultivated and exposed to UVB (15 kJ/m2/day for 3 days) in order to investigate their ability to produce vitamin D3 by conversion of 7-dehydrocholesterol. In addition, N. oceanica was exposed to UVB as a wet paste and dried biomass in order to investigate vitamin D3 production at different processing steps. Other fat-soluble vitamins and provitamin D3, lipids, fatty acids, proteins and amino acids were determined to evaluate the effect of UVB exposure in N. oceanica and D. salina. Most of the cultures were capable of producing vitamin D3 when UVB exposed (D. salina (145 ± 11 ng/g DM), N. oceanica (285 ± 5 ng/g DM), and N. limnetica (2700 ± 198 ng/g DM)), whereas T. suecica was not able to produce vitamin D3. UVB exposed wet paste and dry biomass of N. oceanica was shown to contain lower levels of 7-dehydrocholesterol and vitamin D3, 13 ± 0.4 ng/g DM and 2 ± 0.2 ng/g DM, respectively, which suggest that the production of 7-dehydrocholesterol is increasing during UVB exposure of the growing diluted cultures. UVB stimulated accumulation of α-tocopherol and β-carotene in D. salina and α-tocopherol in N. oceanica. On the contrary, UVB had an adverse effect on the protein content in D. salina and β-carotene content in N. oceanica. These findings suggest that UVB exposed microalgae has a potential as a new, vegan, natural and sustainable source of vitamin D3.

Biochemical and Clinical Effects of Vitamin E Supplementation in Hungarian Smith-Lemli-Opitz Syndrome Patients.

Smith-Lemli-Opitz syndrome (SLOS) is a severe monogenic disorder resulting in low cholesterol and high 7-dehydrocholesterol (7-DHC) levels. 7-DHC-derived oxysterols likely contribute to disease pathophysiology, and thus antioxidant treatment might be beneficial because of high oxidative stress. In a three-year prospective study, we investigated the effects of vitamin E supplementation in six SLOS patients already receiving dietary cholesterol treatment. Plasma vitamin A and E concentrations were determined by the high-performance liquid chromatography (HPLC) method. At baseline, plasma 7-DHC, 8-dehydrocholesterol (8-DHC) and cholesterol levels were determined by liquid chromatography–tandem mass spectrometry (LC-MS/MS) method. The clinical effect of the supplementation was assessed by performing structured parental interviews. At baseline, patients were characterized by low or low–normal plasma vitamin E concentrations (7.19–15.68 μmol/L), while vitamin A concentrations were found to be normal or high (1.26–2.68 μmol/L). Vitamin E supplementation resulted in correction or significant elevation of plasma vitamin E concentration in all patients. We observed reduced aggression, self-injury, irritability, hyperactivity, attention deficit, repetitive behavior, sleep disturbance, skin photosensitivity and/or eczema in 3/6 patients, with notable individual variability. Clinical response to therapy was associated with a low baseline 7-DHC + 8-DHC/cholesterol ratio (0.2–0.4). We suggest that determination of vitamin E status is important in SLOS patients. Supplementation of vitamin E should be considered and might be beneficial.

Voltammetry of 7-dehydrocholesterol as a new and useful tool for Smith-Lemli-Opitz syndrome diagnosis

7-Dehydrocholesterol is an essential biomarker of Smith-Lemli-Opitz syndrome, a congenital autosomal recessive disorder. This study shows for the first time that electrochemical oxidation of 7-dehydrocholesterol can be used for its voltammetric determination. Two classes of supporting electrolytes in acetonitrile and a mixture of acetonitrile-water were used: inorganic acids known to promote structural changes of steroids and indifferent electrolytes. Oxidation of 7-dehydrocholesterol at ca +0.8 V (vs. Ag/AgNO3 in acetonitrile) in 0.1 mol L−1 NaClO4 in acetonitrile is useful for its voltammetric detection using common bare electrode materials. Detection limits for 7-dehydrocholesterol lie in the low micromolar range for all the working electrodes, including boron-doped diamond (0.4 μmol L−1) and disposable thin-film platinum electrodes (0.5 μmol L−1), which are advantageous because of the low volumes of studied solutions. After Bligh-Dyer extraction, quantification of 7-dehydrocholesterol concentration (boron-doped diamond) or concentration range (thin-film platinum) is easily attainable in artificial serum. The mere knowledge of the concentration range provides clinically valuable information, as 7-dehydrocholesterol levels are employed for SLOS diagnosis as a binary criterion (elevated, tens to hundreds μmol L−1 in symptomatic/non-elevated, typically bellow 1 μmol L−1 in healthy individuals in plasma). Moreover, it is shown that 7-dehydrocholesterol (provitamin D3) and cholecalciferol (vitamin D3) can be oxidized in 0.1 mol L−1 HClO4 in acetonitrile. Under these conditions, their voltammetric response changes dramatically, and their oxidation potential difference transiently increases from 0.08 V to 0.25 V, which should facilitate their simultaneous voltammetric determination. This work constitutes a foundation for a reliable and straightforward method for Smith-Lemli-Opitz syndrome diagnosis and monitoring 7-dehydrocholesterol’s biotransformation to cholecalciferol.

Effect of dietary macronutrients on intestinal cholesterol absorption and endogenous cholesterol synthesis: a randomized crossover trial

Background and aimsExtensive research showed a diurnal rhythm of endogenous cholesterol synthesis, whereas recent research reported no diurnal rhythm of intestinal cholesterol absorption in males who consumed low-fat meals. Little is known about the acute effect of macronutrient consumption on cholesterol metabolism, and hence if meal composition may explain this absence of rhythmicity in cholesterol absorption. Therefore, we examined the effect of a high-fat, high-carbohydrate, and high-protein meal on postprandial intestinal cholesterol absorption and endogenous cholesterol synthesis in apparently healthy overweight and slightly obese males. Methods and resultsEighteen males consumed in random order an isoenergetic high-fat, high-carbohydrate, and high-protein meal on three occasions. Serum total cholesterol concentrations, cholesterol absorption markers (campesterol, cholestanol, and sitosterol), and cholesterol synthesis intermediates (7-dehydrocholesterol, 7-dehydrodesmosterol, desmosterol, dihydrolanosterol, lanosterol, lathosterol, zymostenol, and zymosterol) were measured at baseline (T0) and 240 min postprandially (T240). Meal consumption did not significantly change total cholesterol concentrations and cholesterol absorption marker levels (all p > 0.05). Serum levels of 7-dehydrocholesterol, lanosterol, lathosterol, zymostenol, and zymosterol decreased significantly between T0 and T240 (all p < 0.05). These decreases were not significantly different between the three meals (all p > 0.05), except for a larger decrease in dihydrolanosterol levels after the high-fat versus the high-carbohydrate meal (p = 0.009). ConclusionThe high-fat, high-carbohydrate, and high-protein meal did not significantly influence postprandial intestinal cholesterol absorption. Several cholesterol synthesis intermediates decreased postprandially, but the individual macronutrients did not differentially affect these intermediates, except for a possible effect on dihydrolanosterol. Trial registrationClinicalTrials.gov, NCT03139890.

Generation and validation of a conditional knockout mouse model for the study of the Smith-Lemli-Opitz syndrome

Smith-Lemli-Opitz Syndrome (SLOS) is a developmental disorder (OMIM #270400) caused by autosomal recessive mutations in the Dhcr7 gene, which encodes the enzyme 3β-hydroxysterol-Δ7 reductase. SLOS patients present clinically with dysmorphology and neurological, behavioral, and cognitive defects, with characteristically elevated levels of 7-dehydrocholesterol (7-DHC) in all bodily tissues and fluids. Previous mouse models of SLOS have been hampered by postnatal lethality when Dhcr7 is knocked out globally, while a hypomorphic mouse model showed improvement in the biochemical phenotype with aging and did not manifest most other characteristic features of SLOS. We report the generation of a conditional knockout of Dhcr7 (Dhcr7flx/flx), validated by generating a mouse with a liver-specific deletion (Dhcr7L-KO). Phenotypic characterization of liver-specific knockout mice revealed no significant changes in viability, fertility, growth curves, liver architecture, hepatic triglyceride secretion, or parameters of systemic glucose homeostasis. Furthermore, qPCR and RNA-Seq analyses of livers revealed no perturbations in pathways responsible for cholesterol synthesis, either in male or in female Dhcr7L-KO mice, suggesting that hepatic disruption of postsqualene cholesterol synthesis leads to minimal impact on sterol metabolism in the liver. This validated conditional Dhcr7 knockout model may now allow us to systematically explore the pathophysiology of SLOS, by allowing for temporal, cell and tissue-specific loss of DHCR7.

Bile acid biosynthesis in Smith-Lemli-Opitz syndrome bypassing cholesterol: Potential importance of pathway intermediates

Bile acids are the end products of cholesterol metabolism secreted into bile. They are essential for the absorption of lipids and lipid soluble compounds from the intestine. Here we have identified a series of unusual Δ5-unsaturated bile acids in plasma and urine of patients with Smith-Lemli-Opitz syndrome (SLOS), a defect in cholesterol biosynthesis resulting in elevated levels of 7-dehydrocholesterol (7-DHC), an immediate precursor of cholesterol. Using liquid chromatography – mass spectrometry (LC–MS) we have uncovered a pathway of bile acid biosynthesis in SLOS avoiding cholesterol starting with 7-DHC and proceeding through 7-oxo and 7β-hydroxy intermediates. This pathway also occurs to a minor extent in healthy humans, but elevated levels of pathway intermediates could be responsible for some of the features SLOS. The pathway is also active in SLOS affected pregnancies as revealed by analysis of amniotic fluid. Importantly, intermediates in the pathway, 25-hydroxy-7-oxocholesterol, (25R)26-hydroxy-7-oxocholesterol, 3β-hydroxy-7-oxocholest-5-en-(25R)26-oic acid and the analogous 7β-hydroxysterols are modulators of the activity of Smoothened (Smo), an oncoprotein that mediates Hedgehog (Hh) signalling across membranes during embryogenesis and in the regeneration of postembryonic tissue. Computational docking of the 7-oxo and 7β-hydroxy compounds to the extracellular cysteine rich domain of Smo reveals that they bind in the same groove as both 20S-hydroxycholesterol and cholesterol, known activators of the Hh pathway.

Síndrome de Smith-Lemli-Opitz: Revisión de la literatura a propósito de un caso

Skin reactions induced by drugs in pediatrics are rare entities; However, these are associated Smith-Lemli-Opitz syndrome is an autosomal recessive disorder characterized by multiple congenital malformation, intellectual disability and behavioral problems. It is due to mutations of DHCR7 with a deficiency of 7-dehydrocholesterol reductase. This enzyme catalyzes the reduction of 7-dehydrocholesterol to cholesterol. Therefore, it results inincreased 7-dehydrocholesterol levels and other cholesterol precursors, and decreased cholesterol levels in blood and biological tissues. Its phenotypic spectrum varies broadly with characteristic physical malformations such as microcephaly, characteristic face, genital abnormalities in male patients, intellectual disability and syndactyly of the second and third toes. The clinical diagnosis is confirmed by finding elevated 7-dehydrocholesterol and mutations in DHCR7, and prenatal diagnosis is also possible. The treatment is a symptomatic treatment and dietary cholesterol supplementation is beneficial. On the other hand, other therapies are being studied such as simvastatin treatment and antioxidant supplementation.

Identification and characterization of prescription drugs that change levels of 7-dehydrocholesterol and desmosterol

Regulating blood cholesterol (Chol) levels by pharmacotherapy has successfully improved cardiovascular health. There is growing interest in the role of Chol precursors in the treatment of diseases. One sterol precursor, desmosterol (Des), is a potential pharmacological target for inflammatory and neurodegenerative disorders. However, elevating levels of the precursor 7-dehydrocholesterol (7-DHC) by inhibiting the enzyme 7-dehydrocholesterol reductase is linked to teratogenic outcomes. Thus, altering the sterol profile may either increase risk toward an adverse outcome or confer therapeutic benefit depending on the metabolite affected by the pharmacophore. In order to characterize any unknown activity of drugs on Chol biosynthesis, a chemical library of Food and Drug Administration-approved drugs was screened for the potential to modulate 7-DHC or Des levels in a neural cell line. Over 20% of the collection was shown to impact Chol biosynthesis, including 75 compounds that alter 7-DHC levels and 49 that modulate Des levels. Evidence is provided that three tyrosine kinase inhibitors, imatinib, ponatinib, and masitinib, elevate Des levels as well as other substrates of 24-dehydrocholesterol reductase, the enzyme responsible for converting Des to Chol. Additionally, the mechanism of action for ponatinib and masitinib was explored, demonstrating that protein levels are decreased as a result of treatment with these drugs.

Compromised phagosome maturation underlies RPE pathology in cell culture and whole animal models of Smith-Lemli-Opitz Syndrome

ABSTRACTTreatment of rats with the cholesterol pathway inhibitor AY9944 produces an animal model of Smith-Lemli-Opitz syndrome (SLOS), an autosomal recessive disease caused by defective cholesterol synthesis. This SLOS rat model undergoes progressive and irreversible degeneration of the neural retina, with associated pathological features of the retinal pigmented epithelium (RPE). Here, we provide further insights into the mechanism involved in the RPE pathology. In the SLOS rat model, markedly increased RPE apical autofluorescence is observed, compared to untreated animals, which correlates with increased levels of A2E and other bisretinoids. Utilizing cultured human induced pluripotent stem cell (iPSC)- derived SLOS RPE cells, we found significantly elevated steady-state levels of 7-dehydrocholesterol (7DHC) and decreased cholesterol levels (key biochemical hallmarks of SLOS). Western blot analysis revealed altered levels of the macroautophagy/autophagy markers MAP1LC3B-II and SQSTM1/p62, and build-up of ubiquitinated proteins. Accumulation of immature autophagosomes was accompanied by inefficient degradation of phagocytized, exogenously supplied retinal rod outer segments (as evidenced by persistence of the C-terminal 1D4 epitope of RHO [rhodopsin]) in SLOS RPE compared to iPSC-derived normal human control. SLOS RPE cells exhibited lysosomal pH levels and CTSD activity within normal physiological limits, thus discounting the involvement of perturbed lysosomal function. Furthermore, 1D4-positive phagosomes that accumulated in the RPE in both pharmacological and genetic rodent models of SLOS failed to fuse with lysosomes. Taken together, these observations suggest that defective phagosome maturation underlies the observed RPE pathology. The potential relevance of these findings to SLOS and the requirement of cholesterol for phagosome maturation are discussed.

Recovery of lipid metabolic alterations in hepatitis C patients after viral clearance: Incomplete restoration with accelerated ω-oxidation

How hepatitis C virus (HCV)-associated lipid metabolic alterations recover after sustained virological response (SVR) remains elusive. The aforementioned recovery pattern was investigated. In a prospective cohort study of 438 chronic hepatitis C (CHC) patients with SVR after anti-HCV therapy, 164 sex- and age-matched genotype I (G1) and G2 patients underwent paired-serum liquid chromatography-tandem mass spectrometry analyses before and 24 weeks after therapy. Subjects without CHC served as controls (n=100). CHC patients had lower baseline lipid levels than controls. Among CHC patients, pre-therapy total cholesterol levels were positively associated with HCV RNA levels; G1 patients had higher pre-therapy HCV RNA levels than G2 patients. Repeated measures analysis of variance of CHC patients showed that lathosterol, lanosterol, total hydroxysphingomyelin, and total phosphatidylcholines levels, and total dicarboxyacylcarnitine/total acylcarnitine (indicators of ω-oxidation) and pre-β-lipoprotein ratios elevated 24 weeks after therapy compared with the levels before therapy. Levels of total lysophosphatidylcholines and α- and β-lipoprotein ratios decreased. Subgroup analyses showed elevated 7-dehydrocholesterol and lanosterol levels, particularly in G2 and male patients, who had broader spectra of altered phosphatidylcholines and acylcarnitines than G1 and female patients, respectively. Compared with controls, CHC patients had higher post-therapy levels of total lysophosphatidylcholines and hydroxysphingomyelins and ratios of total dicarboxyacylcarnitines/total acylcarnitines but lower cholesterol levels. At 24weeks after therapy, accelerated cholesterol biosynthesis, hepatic lipid export, ω-oxidation, and decreased systemic inflammation were noted in CHC patients with SVR, with greater efficiency in G2 and male patients. Regardless, HCV-associated lipid metabolic alterations required >24weeks for restoration or were incompletely reversible after SVR.

Effects of HIV on metabolic and biological pathways of CD4+ T lymphocytes.

The effects of human immunodeficiency virus (HIV) on the metabolic and biological pathways of cluster of differentiation (CD)4+ T lymphocytes were investigated. A total of 150 patients with acquired immune deficiency syndrome (AIDS) and 50 healthy individuals who were admitted to hospital for physical examination during the period of June 2016 to January 2017, were selected as subjects in the present study. According to the virus load, 150 AIDS patients were divided into three groups: i) Viral load >106 copies/ml (group A, n=39), ii) 104 copies/ml < viral load <105 copies/ml (group B, n=76), and iii) viral load <104 copies/ml (group C, n=35). The relationship between viral loads in the three groups and CD4+ T lymphocyte counts was assessed. Active lymphocytes were isolated from T lymphocytes in the subjects, and the ratio of Th1 to Th2 was measured by flow cytometry. Effects of HIV on human T-lymphocyte differentiation were observed. Differences in T-lymphocyte metabolites were detected by proton nuclear magnetic resonance and their biological pathways analyzed. The results showed that CD4+ T-cell counts were decreased with the increase of the viral loads of patients. The viral loads of AIDS patients differentiated T lymphocytes. In other words, high viral loads accelerated the differentiation of T lymphocytes into Th1 cells. In the high HIV viral load group, the levels of glycerol phosphodiesterase, 7-dehydrocholesterol, p-hydroxyphenylacetic acid, cholesterol and deoxyuridine were increased, but the levels of 3-methoxytyramine, cytidine deaminase, deoxycorticosterone and 3-hydroxybutyric acid were decreased. The viral loads of AIDS patients are associated with CD4+ T-cell counts and the ratio of CD4+ T to CD8+ T cells. At the same time, HIV viral loads can affect the lipid biosynthesis of T-lymphocyte membranes, thus affecting the differentiation and proliferation of T lymphocytes and finally intervening its mediated immune responses.