Search Results (110)

Cytochrome P450, family 7, subfamily b, polypeptide 1 (CYP7B1) is a widely expressed enzyme involved in the hydroxylation of sterols. Generated by transposon technology in zygotes, male rats lacking Cyp7b1 expression in homozygosis showed an absence of Cyp7b1 mRNA expression in the liver, small intestine, adipose tissue, and muscle. Elevated levels of 25-hydroxycholesterol were found in the liver of mutant rats. After overnight fasting, plasma triglyceride (TG) levels were increased in the homozygous rats. In agreement with this, increased hepatic secretion of very-low-density lipoprotein-TG (VLDL) in fasting rats treated with tyloxapol and decreased low-density receptor protein (LDLr) on the hepatocyte plasma membranes were observed. The decrease in LDLr was not due to decreased mRNA expression but to increased expressions of its proteases (Psck9 and Mylip). RNA sequencing identified Fasn, Igfbp2, and Pcsk9 as targets of the Cyp7b1 absence. However, the hepatic protein contents of IGFBP2 were increased in Cyp7b1-deficient rats, accompanied by a normal glucose tolerance test. HepG2 cells lacking CYP7B1 showed increased expressions of FASN and IGFBP2. These results suggest a role of CYP7B1 in the control of hepatic IGFBP2 and VLDL-TG secretion as a prediabetes sign exerted through 25-hydroxycholesterol and transcriptional or translational mechanisms depending on the species. Full article

Long-term effects of concussions, particularly in contact sport athletes, have been linked to changes in neuronal health. Lipid dysregulation has emerged as a potential contributor to neuronal injury and may serve as a measurable biomarker of brain pathology. This study investigated cognitive scores and serum lipid biomarkers in retired rugby players with a history of concussion to assess their association with concussion exposure. Serum levels of 24-hydroxycholesterol (24-HC), 25-HC, 27-HC, total triglycerides, and ceramide were compared between retired rugby players with a history of repeated concussions (n = 26) and non-contact sport controls (n = 19). ELISA-based quantification and statistical analyses identified significant group differences. Concussed athletes exhibited significantly lower serum 24-HC and significantly higher levels of 27-HC, triglycerides, and ceramide compared to controls, while no significant difference was observed for 25-HC. These findings indicate that repeated concussion is associated with reductions in cognitive performance and persistent alterations in serum lipid profiles. The observed lipid changes, particularly in 24-HC, 27-HC, ceramide, and triglycerides, may serve as measurable biomarkers of concussion-related biochemical alterations, providing a foundation for future studies aimed at monitoring neurological health in at-risk populations. Full article

Lipid debris generated after ischemic stroke overwhelms myeloid cells, leading to foam cell-like dysfunction and chronic neuroinflammation. 2-hydroxypropyl-β-cyclodextrin (HPβCD), a cholesterol-mobilizing agent, has been shown to improve recovery and reduce chronic inflammation after stroke by enhancing lipid processing and cholesterol efflux in infarcts. To identify plasma biomarkers of HPβCD activity and gain mechanistic insight into lipid pathway modulation, aged (21-month-old) male mice underwent the distal middle cerebral artery occlusion + hypoxia (DH) model of stroke and received 2 g/kg HPβCD twice daily beginning 1 d after stroke. Plasma metabolomic and lipidomic profiling was performed 4 d after stroke using untargeted (Global Discovery) and targeted (Complex Lipid, Oxysterols, and Lipid Mediators of Inflammation) panels. Acute neuroprotection was assessed by magnetic resonance imaging (MRI) quantification of infarct, ventricle, and hippocampus volumes 2 d after stroke and by plasma neurofilament light (NfL) levels 4 d after stroke. HPβCD treatment did not provide acute neuroprotection; however, HPβCD did induce distinct plasma metabolomic and lipidomic signatures, including decreases in sphingolipids, cholesterol, long-chain fatty acids, 4β-hydroxycholesterol, 7-dehydrocholesterol, and 8-dehydrocholesterol and increases in 27-hydroxycholesterol and 7α-hydroxy-3-oxo-4-cholestenoic acid (7-HOCA), consistent with enhanced cholesterol efflux and metabolism. Pro-inflammatory oxylipins were also suppressed by HPβCD treatment. These results support the role of HPβCD in promoting lipid debris clearance and suppressing inflammatory lipid pathways after stroke and, together with prior studies demonstrating improved long-term recovery, highlight HPβCD as a biomarker-supported therapeutic candidate for stroke recovery. Full article

27-Hydroxycholesterol (27OHChol), a cholesterol metabolite, induces inflammatory responses in monocytic cells and promotes their differentiation into mature dendritic cells. Here, we examined whether inhibition of heat shock protein 90 (HSP90) modulates these responses. Treatment with ganetespib, a selective HSP90 inhibitor, significantly reduced chemokine CCL2 expression, lowering monocytic cell migration. It also suppressed matrix metalloproteinase-9 (MMP-9) expression and attenuated the lipopolysaccharide (LPS) response otherwise amplified by 27OHChol. Furthermore, ganetespib decreased mature dendritic cell markers (CD80, CD83, CD88) and restored endocytic activity, indicating a less activated state. These changes suggest that HSP90 regulates 27OHChol-induced pro-inflammatory activation via its client proteins. To explore this mechanism, we examined the phosphorylation status of signaling proteins. 27OHChol enhanced phosphorylation of Akt and its downstream targets, S6 and 4E-BP1 within the Akt/mTORC1 pathway. Ganetespib reduced total and phosphorylated Akt and 4E-BP1, and selectively inhibited S6 phosphorylation without altering total protein level. Collectively, these findings demonstrate that HSP90 inhibition by ganetespib mitigates 27OHChol-driven monocytic cell activation through suppression of the HSP90-Akt/mTORC1 axis. Targeting this pathway may provide a promising therapeutic strategy for metabolic inflammation associated with oxysterols. Full article

Ivermectin (IVM), a broad-spectrum anthelmintic agent, has anti-inflammatory properties, and affects cellular and humoral immune responses. We recently showed that multiple pro-inflammatory cytokines (e.g., FGF2, CCL5, CD40L) bind to the allosteric site (site 2) of integrins and activate them. 25-Hydroxycholesterol, a pro-inflammatory lipid mediator, is known to bind to site 2 and induce integrin activation and inflammatory signals (e.g., IL-6 and TNF secretion), suggesting that site 2 is critically involved in inflammation. We showed that two anti-inflammatory cytokines (FGF1 and NRG1) bind to site 2 and inhibit integrin activation by inflammatory cytokines. We hypothesized that ivermectin binds to site 2 and inhibits inflammatory signaling by pro-inflammatory cytokines. A docking simulation predicts that ivermectin binds to site 2. Ivermectin inhibits the integrin activation induced by inflammatory cytokines, suggesting that ivermectin is a site 2 antagonist. We showed that TNF, a major pro-inflammatory cytokine, binds to integrin site 2 and induces allosteric integrin activation like other pro-inflammatory cytokines, suggesting that site 2 binding and integrin activation is a potential mechanism of the pro-inflammatory action of these cytokines. Ivermectin suppressed the activation of soluble β3 integrins by TNF and other pro-inflammatory cytokines in a dose-dependent manner in cell-free conditions. Binding to site 2 and the inhibition of binding of inflammatory cytokines may be a potential mechanism of anti-inflammatory action of ivermectin. Full article

An oxysterol, 25-Hydroxycholesterol (25OHChol), is produced through cholesterol oxidation and is involved in various cellular processes, including apoptosis. However, the precise mechanisms underlying 25OHChol-induced apoptosis in neuroblastoma cells remain unclear. The aim of this study was to elucidate the detailed molecular mechanisms by which 25OHChol induces apoptosis in human neuroblastoma cells. This study explores the apoptotic effects of 25OHChol and the associated signaling pathways in BE(2)-C cells, a widely used human neuroblastoma cell model for neuronal differentiation and cancer research. To evaluate the cytotoxicity of 25OHChol, cell viability was assessed using the CCK-8 assay, which demonstrated a concentration-dependent decline, indicating a potential induction of cell death. Morphological changes characteristic of apoptosis, such as nuclear condensation and fragmentation, were confirmed via DAPI staining. Additionally, Annexin V/PI flow cytometry analysis revealed an increase in late apoptotic cell populations, further corroborating apoptosis induction. To investigate the molecular mechanisms, we analyzed the expression of Bcl-2 family proteins via Western blotting. The results showed an elevated Bax/Bcl-2 ratio, suggesting activation of the intrinsic mitochondrial apoptotic pathway. This was further supported by a reduction in mitochondrial membrane potential (MMP), as measured by flow cytometry. Increased caspase-9 and caspase-3/7 activity provided additional evidence for caspase-mediated apoptosis. Moreover, treatment with the pan-caspase inhibitor Z-VAD-FMK led to a dose-dependent increase in cell viability, confirming the essential role of caspases in 25OHChol-induced apoptosis. In conclusion, this study demonstrates that 25OHChol triggers apoptosis in BE(2)-C neuroblastoma cells through activation of the intrinsic mitochondrial apoptotic pathway. These findings provide new insights into the cytotoxic effects of 25OHChol and its potential role in neuroblastoma cell death. Full article

Background/Objectives: Rest–activity rhythm (RAR) disturbances can contribute to aging and dementia via metabolic dysregulation. Hydroxycholesterol (OH) is thought to mediate the link between hypercholesterolemia and neurodegeneration. This study compared sleep and RAR parameters between amnestic mild cognitive impairment (aMCI) patients and normal controls (NCs), and examined their associations with plasma 27-OH levels, reflecting peripheral cholesterol metabolism. Methods In total, 18 aMCI patients (76.6 ± 6.1 years) and 21 NCs (70.4 ± 6.7 years) underwent five-day actigraphy and dim light melatonin onset assessment. Plasma 27-OH levels were measured via high-performance liquid chromatography-mass spectrometry. Generalized linear models (GLMs) were used to analyze the relationships between sleep, RAR, and 27-OH levels. Results: The aMCI group had significantly lower 27-OH levels and 27-OH/total cholesterol ratios (p < 0.05). GLM revealed that longer sleep onset latency (SOL) was associated with higher 27-OH levels in aMCI, distinguishing them from NCs. Additionally, in aMCI, longer SOL, lower sleep efficiency (SE), and higher fragmentation index (FI) were associated with an increased 27-OH/total cholesterol ratio (p < 0.05). Higher relative amplitude of RAR was linked to lower 27-OH levels across groups (p < 0.01), but RAR parameters showed no significant association with the 27-OH/total cholesterol ratio. Sleep disturbances, including prolonged SOL, reduced SE, and increased FI, were associated with altered peripheral cholesterol oxygenation in aMCI. Conclusions: Greater RAR amplitude correlated with lower 27-OH levels, regardless of cognitive status. These findings suggest that peripheral cholesterol oxygenation in aMCI is related to both sleep disturbances and circadian rhythm dysregulation, highlighting their role in cholesterol metabolism and neurodegeneration. Full article

Oxysterols can be derived from the diet, physiologically produced via specific enzymes, or are generated by autoxidation. These molecules have physiological properties and can also adversely affect vital organs. Indeed, some of them have pro-oxidant and pro-inflammatory activities and can lead to major pathologies. The present review focuses on oxysterols (7-ketocholesterol, 7β-hydroxycholesterol, 25-hydroxycholesterol, 27-hydroxycholesterol, 5,6α-epoxycholesterol, 5,6β-epoxycholesterol, and cholestane-3β, 5α, 6β-triol) involved either in cholesterol metabolism, age-related diseases (such as cardiovascular, neurodegenerative, and eye diseases, e.g., sarcopenia), and inflammatory diseases (especially Behcet’s disease and bowel and lung diseases (e.g., sarcoidosis, COVID-19)). Metabolic pathways associated with oxysterol-induced inflammation are discussed considering the cytokinic TLR4 pathway, non-cytokinic pathways, and the contribution of Ca²⁺ and K⁺ channels. Therapeutic approaches targeting oxysterol-induced inflammation either by natural or synthetic molecules are also presented. Full article

The tissue renin–angiotensin system (RAS) is a regulator of oxidative and inflammatory homeostasis by balancing its pro-oxidative/pro-inflammatory axis (angiotensin II, AngII, and AngII type-1 receptor, AT1) and its anti-oxidative/anti-inflammatory axis (AngII/AT2 and ACE2/Ang1-7/Mas receptors). An RAS dysregulation contributes to diseases, including Parkinson’s disease (PD). Immune mechanisms are involved in PD. An increase in levels of pro-oxidative/pro-inflammatory autoantibodies for AT1 (AT1-AAs) and ACE2 (ACE2-AAs) has been recently observed in PD. However, it is not known whether dysregulation of autoantibodies for AT2, MasR, and the correlations among different RAS-AAs occurs in PD. In 106 controls and 117 PD patients, we used enzyme-linked immunosorbent assays to determine correlations among serum RAS-AAs, and among RAS-AAs and pro-inflammatory cytokines and 27-hydroxycholesterol. PD patients showed an increase in MasR-AAs, and a more interconnected cluster of correlations among RAS-AAs (AT1-AA, AT2-AA, MasR-AA, ACE2-AA), changes in RAS-AA networks with sex and age, and differences in networks between RAS-AAs and major PD-related pro-inflammatory cytokines and 27-hydroxycholesterol. The association between AT1-AAs and PD remained significant even after adjustment for age and other variables. This study reveals a disease-specific network of RAS autoantibodies in PD that links immune and oxidative pathways and identifies new biomarker patterns and potential therapeutic targets. Full article

We showed that multiple inflammatory cytokines (e.g., CCL5, CXCL12, CX3CL1, CD40L, and FGF2) bind to the allosteric site (site 2) of integrins, distinct from the classical RGD-binding site (site 1), and allosterically activate integrins. A major inflammatory lipid mediator 25-hydroxycholesterol is known to bind to site 2 and allosterically activates integrins and induces inflammatory signals (e.g., IL-6 and TNF secretion). Thus, site 2 is involved in inflammatory signaling. Neuregulin-1 (NRG1) is known to suppresses the progression of inflammatory diseases, fibrosis, and insulin resistance. But, the mechanism of anti-inflammatory action of NRG1 is unclear. We previously showed that NRG1 binds to the classical RGD-binding site (site 1). Mutating the 3 Lys residues that are involved in site 1 binding (NRG1 3KE mutant) is defective in binding to site 1 and in ErbB3-mediated mitogenic signals. Docking simulation predicted that NRG1 binds to site 2. We hypothesized that NRG1 acts as an antagonist of site 2 and blocks allosteric activation by multiple cytokines. Here, we describe that NRG1 binds to site 2 but does not activate soluble αvβ3 or αIIbβ3 in 1 mM Ca²⁺, unlike inflammatory cytokines. Instead, NRG1 suppressed integrin activation by several inflammatory cytokines, suggesting that NRG1 acts as a competitive inhibitor of site 2. Wild-type NRG1 is not suitable for long-term treatment due to its mitogenicity. We showed that the non-mitogenic NRG1 3KE mutant still bound to site 2 and inhibited allosteric activation of soluble and cell-surface integrins, suggesting that NRG1 3KE may have potential as a therapeutic. Full article

Background/Objectives: Alterations of oxysterols and gut microbiota have been recognized as indicators affecting mild cognitive impairment (MCI) and sarcopenia, respectively, whereas their association with co-dysfunction has not been investigated. Methods: In this study, a total of 1035 individuals were divided into Control (n = 264), MCI (n = 435), and MCI with possible sarcopenia (MPS, n = 336) groups. Cognition and muscle indexes, serum oxysterols, and gut microbiota were measured. Spearman’s rank coefficients were calculated to determine their correlations. Results: Performances of global and multidimensional cognitive tests was successively worse in the Control, MCI, and MPS groups. Longer duration of five-time chair stand test, lower 6-meter walk speed, and handgrip strength were observed in the MPS group, along with increased 27-hydroxycholesterol (27-OHC) and 5α,6α-epoxycholesterol and decreased 5α-Cholest-8(14)-ene-3β,15α-diol (15-HC). Higher concentrations of amyloid precursor protein (APP), neurofilament, and C-terminal agrin fragment (CAF) were discovered in the MCI and MPS groups. The α-diversity of gut microbiota in the MCI and MPS group was remarkably decreased, followed by a shifted abundance of microbial taxa, such as Alistipes and Rikenellaceae. Multiple significant correlations were found between cognition and muscle indexes and with oxysterols. Conclusions: Our study indicates that oxysterols and gut microbiota are prominently involved in the co-dysfunction of cognition and muscle. Full article

Cholesterol is an essential element for the development and normal function of the central nervous system. While peripheral cholesterol is influenced by liver metabolism and diet, brain cholesterol metabolism takes place in an isolated system due to the impermeability of the blood–brain barrier (BBB). However, cross-talk occurs between the brain and periphery, specifically through metabolites such as oxysterols that play key roles in regulating cholesterol balance. Several neurodegenerative conditions such as Alzheimer’s disease or Parkinson’s disease are considered to be affected by the loss of this balance. Also, the treatment of hypercholesterolemia needs to consider these discrete interferences between brain and peripheral cholesterol and the possible implications of each therapeutic approach. This is particularly important because of 27-hydroxycholesterol and 24-hydroxycholesterol, which can cross the BBB and are involved in cholesterol metabolism. This paper examines the metabolic pathways of cholesterol metabolism in the brain and periphery and focuses on the complex cross-talk between these metabolisms. Also, we emphasize the regulatory role of the BBB and the need for an integrated approach to cholesterol management. Full article

Oxysterols, as metabolites of cholesterol, play a key role in cholesterol homeostasis, autophagosome formation, and regulation of immune responses. Disorders in oxysterol metabolism are closely related to the pathogenesis of neurodegenerative diseases. To systematically investigate the profound molecular regulatory mechanisms of neurodegenerative diseases, it is necessary to quantify oxysterols and their metabolites in central and peripheral biospecimens simultaneously and accurately. However, there are a lot of unsolved problems with the existing methods, such as the hindrance of applying a single method to different biological specimens or the challenge of simultaneous quantification due to differential groups on the ends of the oxysterol side chains. Herein, according to the physicochemical properties and structure of oxysterols, an optimized liquid chromatography-tandem mass spectrometry method for the quantification of oxysterols was established by optimizing the sample preparation process, chromatographic conditions, mobile phase pH, and solvent selection. Seven oxysterols were detected by this method, including 27-hydroxycholesterol, 7α-hydroxycholesterol, 7α,27-dihydroxycholesterol, 7-dehydrocholesterol, 7α-hydroxy-3-oxo-4-cholestenoic acid, 3-hydroxy-5-cholestenoic acid, and 24(S)-hydroxycholesterol. Non-derivatization extraction with methyl tert-butyl ether was used for different biospecimens, followed by simultaneous chromatographic separation of oxysterols on a phenyl hexyl column. By repeated validation, this method exhibited satisfactory linearity, precision, recovery, sensitivity, repeatability, and stability, and it was successfully applied to the detection of oxysterols in the plasma, cerebral cortex, and liver of mouse. In summary, our optimized method enables concurrent analysis and quantification of oxysterols and their metabolites in various biospecimens, presenting a broad range of applicability. Full article

Microglia play a crucial role as immune cells responsible for the brain’s defense mechanisms. Similar to the actions of macrophages in the body, microglial cells elicit an inflammatory immune response in the brain. Recent papers highlight activated microglial cells as pivotal contributors to inflammatory responses in the brain, leading to damage to nerve tissue and the onset of Alzheimer’s disease (AD). In the brains of AD patients, elevated levels of inflammatory cytokines such as interleukin-6 (IL-6) and oxidized cholesterol metabolites (oxysterols) are observed. These factors are closely associated with inflammatory diseases in the brain. 4′-O-Methylalpinum isoflavone (mAI), derived from Cudrania tricuspidata fruit, possesses antioxidant, neuroprotective, and anti-inflammatory properties. Consequently, this study examined the effect of mAI on the expression of IL-6, a major inflammatory cytokine. The HMC3 microglial cell line was treated with oxysterols to assess the effectiveness of mAI in mitigating this inflammatory response. The results indicated that mAI inhibited the gene expression and protein secretion of IL-6 induced by 25-hydroxycholesterol (25OHChol) and 27-hydroxycholesterol (27OHChol). Furthermore, the expression of MHC class II, a marker for microglial activation, was reduced to baseline levels. These findings suggest that mAI may serve as a viable option for suppressing and treating brain inflammatory diseases induced by cholesterol oxidation products. This is achieved by curtailing the expression of the inflammatory cytokine resulting from the activation of microglial cells by immuno-oxysterol. Full article