Ceramide in cerebrovascular diseases

Impact of sodium-glucose cotransporter-2 inhibitors on aging biomarkers and plasma ceramide levels in type 2 diabetes: beyond glycemic control

BACKGROUND

Aging is a complex biological process marked by the decline of physiological functions and heightened susceptibility to chronic illnesses, notably cardiometabolic disorders. Ceramides (Cer) are lipid derivatives linked to aging and metabolic diseases. Sodium-Glucose Cotransporter-2 inhibitors (SGLT2i), widely used in managing type 2 diabetes, have an unclear impact on aging biomarkers and Cer profiles.

OBJECTIVE

This study explored the association between SGLT2i use, plasma Cer levels (CerC16:0, CerC18:0, CerC22:0, CerC24:0, and CerC24:1), and aging biomarkers-Human Insulin-Like Growth Factor 1 (IGF-1), mammalian target of rapamycin (mTOR), 5-Methylcytosine (5MC), and Human H2AFX (Histone H2AX) in patients with type 2 diabetes mellitus (T2DM).

METHODS

In this retrospective study, 95 participants were divided into three groups: patients on SGLT2i (n = 34), patients on non-SGLT2i anti-diabetic treatments (n = 36), and healthy controls (n = 25). Plasma Cer and aging biomarkers were quantified using Liquid Chromatography with tandem mass spectrometry (LC-MS-MS) and ELISA, respectively. Principal component analysis (PCA) assessed group-based clustering, while ANCOVA evaluated group differences with confounder adjustment.

RESULTS

SGLT2i-treated patients showed significantly lower CerC16:0, CerC22:0, and CerC24:1 levels (p < 0.01) and decreased 5MC and H2AX (p < 0.05) compared to non-SGLT2i patients. IGF-1 was significantly elevated in the SGLT2i group (p < 0.01), suggesting a possible protective effect on metabolic health. PCA distinguished control from diabetic groups but revealed overlap between SGLT2i and non-SGLT2i groups.

CONCLUSION

Beyond glucose control, SGLT2i may improve plasma Cer and aging markers in diabetic patients, supporting their broader therapeutic potential in aging and age-related diseases. Further large-scale studies are warranted to confirm these effects and underlying mechanisms.

Tongfu Xingshen capsule alleviates stroke-associated pneumonia-induced multiple organ injuries by modulating the gut microbiota and sphingolipid metabolism

BACKGROUND

Stroke-associated pneumonia (SAP) represents a major complication and cause of death in patients suffering from intracerebral haemorrhage (ICH). It's urgent to develop more effective therapeutic strategies. Tongfu Xingshen capsule (TFXS) is a traditional Chinese medicine that has been utilised in clinical studies for the treatment of ICH and SAP, but the underlying mechanisms remain to be fully elucidated.

PURPOSE

This study aims to explore the therapeutic effects and mechanisms of TFXS on SAP using an aspiration-induced Klebsiella pneumoniae infection-complicating ICH rat model and an intratracheal injection of lipopolysaccharide (LPS)-induced acute lung injury-complicating ICH rat model.

METHODS

The chemical components of TFXS are characterised using ULPLC-Q Exactive-Orbitrap-MS. The therapeutic effects of TFXS are evaluated through neurological scoring, histopathology analysis, magnetic resonance imaging, immunofluorescence, Alcian blue-nuclear fast red staining, myeloperoxidase activity assessment, leukocyte counting, and ELISA. To investigate the underlying mechanisms, faecal microbiota transplantation, 16S rRNA sequencing, untargeted metabolomics, and Spearman correlation analyses are performed.

RESULTS

A total of 60 compounds are identified in TFXS. Pharmacological analysis reveals that TFXS significantly mitigates neurological deficits, enhances haematoma absorption, attenuates brain damage and neuroinflammation, and improves pneumonia and pulmonary injury by reducing the infiltration of leukocytes and lymphocytes, as well as suppressing the infiltration and overactivation of neutrophils. TFXS also alleviates intestinal lesions and barrier damage by increasing acidic mucins and the expression of the tight junction protein zonula occludens-1 (ZO-1). Mechanistically, TFXS ameliorates pneumonia and pulmonary injury in a gut microbiota-dependent manner. It reverses sphingolipid metabolism disorders and ceramide accumulation by modulating SAP-induced gut microbiota dysbiosis and enhancing the abundance of probiotics, including Lactobacillus, Allobaculum and Enterococcus.

CONCLUSION

TFXS exerts anti-inflammatory and protective effects on the brain, lung, and gut by alleviating gut microbiota dysbiosis and sphingolipid metabolism disorders. These findings highlight TFXS as a promising therapeutic candidate for the treatment of SAP.

Lipidomic profiling of the cerebrospinal fluid in moyamoya angiopathy patients

BACKGROUND

Moyamoya angiopathy (MA) is a rare cerebrovascular disorder which can occur in both children and young adults, characterized by progressive occlusion of the intracranial carotid arteries, leading patients to ischemic and haemorrhagic strokes. Despite decades of research, the mechanisms underlying MA remain poorly clarified and current gaps in the understanding of pathogenesis have hampered the development of suitable preventive strategies and therapeutic options. Moreover, clinically approved biomarkers for MA patients' stratification are missing. The unknown pathophysiology and the lack of reliable biomarkers prompted us to investigate cerebrospinal fluid (CSF) lipidome through state-of-the-art lipidomics.

METHODS

Intraoperative CSF from a subgroup of MA patients in comparison to age/sex matched controls (CTRL) was analysed through LC-MS/MS, by an untargeted lipidomic approach. Receiver operating characteristic (ROC) curve and simple linear regression analyses were performed for diagnostic use. We searched for simultaneously altered lipids in plasma and CSF of MA patients.

RESULTS

Overall, we observed a significant increase of sphingolipids (p < 0.05) and phospholipids (p < 0.05) in MA CSF. A partial least squares discriminant analysis clearly separated MA and CTRL by 64% on Principal Component 1. We identified lipid classes (n = 12) with a Variance Importance in Projection score ≥ 1.5, within those lipids highly correlated with MA (n = 70). A significant increase in acylcarnitines, sphingolipids (sphingomyelins and ceramides), phospholipids (lysophosphatidylcholines; phosphatidylcholines; phosphatidylethanolamines; ether-phosphatidylethanolamines; ether-phosphatidylcholines) and cholesterol esters was found by multivariate and univariate analyses. Monoacylglycerols were the only lipid class displaying a markedly significant (p < 0.001) decrease in CSF of MA patients as compared to CTRL subjects. The ROC curve and simple linear regression analysis identified 10 out of 12 lipid classes as reliable MA biomarkers, mainly dealing with phospholipids. We then compared current and previous data on plasma lipidomic profile. The discriminant analysis returned n = 175 (in plasma) and n = 70 (in CSF) simultaneously altered lipids respectively, and phosphatidylcholines (n = 10) resulted as commonly decreased in plasma and increased in CSF.

CONCLUSIONS

Our findings highlighted a strong pro-inflammatory environment in MA CSF. These preliminary hallmarks could be helpful to decipher the complex MA pathogenesis, by supplying candidate biomarkers for patient stratification.

Ceramides increase mitochondrial permeabilization to trigger mtDNA-dependent inflammation in astrocytes during brain ischemia

The brain is rich in lipids, and disorders or abnormalities in lipid metabolism can induce neurotoxicity. Ceramides are the central intermediates of sphingolipid metabolism. This study was designed to investigate the potential lipotoxicity of ceramides in brain ischemia. First, a pseudo-targeted lipidomics analysis of plasma samples from stroke patients found significantly elevated levels of long-chain ceramides. A similar observation was made in mice subjected to permanent middle cerebral artery occlusion (pMCAO) surgery. In cultured cells, it was found that the altered ceramides were mainly derived from astrocytes via de novo pathway, and SPTLC2 was a key regulator because Sptlc2 knockdown largely blocked ceramide production. Ceramides induced astrocyte activation and triggered oxidative stress to impair mitochondrial homeostasis by increasing mitochondrial permeabilization. Moreover, ceramides triggered the formation of voltage-dependent anion channel (VDAC) oligomers in the mitochondrial outer membrane, through which mtDNA was released into the cytoplasm. Similar to oxygen and glucose depletion treatment, ceramides also increased cGAS activity and STING protein expression. However, this activity was diminished in the presence of the mitochondrial ROS scavenger SKQ1, indicating the involvement of oxidative stress in ceramide action. By facilitating cGAS/STING signaling cascades, ceramides resultantly induced interferon response to aggravate inflammatory damage in the ischemic brain. To address the impact of ceramides on brain ischemic injury in vivo, ceramide generation was blocked in the brain by injection of AAV9-Sptlc2 shRNA in pMCAO mice. Sptlc2 knockdown in the brain reduced ceramide generation and attenuated brain ischemic damage with astrocyte inactivation. As expected, Sptlc2 deficiency effectively blocked cGAS/STING pathway-dependent interferon responses. Together, these findings suggest a new therapeutic strategy for pharmacological intervention to attenuate neuroinflammation.

Ceramides may Play a Central Role in the Pathogenesis of Alzheimer's Disease: a Review of Evidence and Horizons for Discovery

While several hypotheses have been proposed to explain the underlying mechanisms of Alzheimer's disease, none have been entirely satisfactory. Both genetic and non-genetic risk factors, such as infections, metabolic disorders and psychological stress, contribute to this debilitating disease. Multiple lines of evidence indicate that ceramides may be central to the pathogenesis of Alzheimer's disease. Tumor necrosis factor-α, saturated fatty acids and cortisol elevate the brain levels of ceramides, while genetic risk factors, such as mutations in APP, presenilin, TREM2 and APOE ε4, also elevate ceramide synthesis. Importantly, ceramides displace sphingomyelin and cholesterol from lipid raft-like membrane patches that connect the endoplasmic reticulum and mitochondria, disturbing mitochondrial oxidative phosphorylation and energy production. As a consequence, the flattening of lipid rafts alters the function of γ-secretase, leading to increased production of Aβ42. Moreover, ceramides inhibit the insulin-signaling cascade via at least three mechanisms, resulting in the activation of glycogen synthase kinase-3 β. Activation of this kinase has multiple consequences, as it further deteriorates insulin resistance, promotes the transcription of BACE1, causes hyperphosphorylation of tau and inhibits the transcription factor Nrf2. Functional Nrf2 prevents apoptosis, mediates anti-inflammatory activity and improves blood-brain barrier function. Thus, various seemingly unrelated Alzheimer's disease risk factors converge on ceramide production, whereas the elevated levels of ceramides give rise to the well-known pathological features of Alzheimer's disease. Understanding and targeting these mechanisms may provide a promising foundation for the development of novel preventive and therapeutic strategies.

Associations of Metabolites Related Salt Sensitivity of Blood Pressure and Essential Hypertension in Chinese Population: The EpiSS Study

BACKGROUND

Salt sensitivity of blood pressure (SSBP) is an important risk factor for essential hypertension and cardiovascular diseases, and its metabolic mechanisms remain poorly understood. This study aimed to identify SSBP-associated metabolic biomarkers and investigate their potential mediating role in the SSBP-hypertension pathophysiology.

METHODS

Based on the Systematic Epidemiological Study of Salt Sensitivity (EpiSS) conducted in 2014-2016, we performed a case-control study involving 54 matched pairs of participants classified as salt-sensitive or salt-resistant with targeted metabolomics detected. Multivariable logistic regression analyses were conducted to assess the metabolites associations with SSBP and hypertension. The diagnostic performance of the model was evaluated using the receiver operating characteristic curve (ROC) analysis yielded an area under the curve (AUC) value, sensitivity, and specificity. Furthermore, the potential mediating effects of targeted metabolites on the relationship between SSBP and essential hypertension were explored.

RESULTS

Three metabolites demonstrated significant SSBP associations: L-Glutamine (OR = 0.998; 95% CI: 0.997, 0.999), PC (16:1/14:0) (OR = 1.039; 95% CI: 1.003, 1.077), and ChE (22:4) (OR = 1.115; 95% CI: 1.002, 1.240). Among them, L-Glutamine demonstrated the highest diagnostic efficiency for SSBP (AUC = 0.766; 95% CI: 0.677, 0.855). The combined model of the three metabolites slightly improved diagnostic efficiency (AUC = 0.788; 95% CI: 0.703, 0.874). L-Glutamine and Cer (d18:0/24:1) were identified as potential protective factors against essential hypertension (p < 0.05). Mediation analyses further indicated that L-Glutamine partially mediated the relationship between SSBP and essential hypertension, demonstrating a suppressive effect.

CONCLUSIONS

This study identified L-Glutamine as both a diagnostic biomarker for SSBP and a metabolic modulator attenuating hypertension risk, providing insights for early SSBP screening and the pathways governing SSBP progression to overt hypertension.

Sphingolipid signaling in kidney diseases

Sphingolipids are a family of bioactive lipids. The key components include ceramides, ceramide-1-phosphate, sphingosine, and sphingosine-1-phosphate. Sphingolipids were originally considered to be primarily structural elements of cell membranes but were later recognized as bioactive signaling molecules that play diverse roles in cellular behaviors such as cell differentiation, migration, proliferation, and death. Studies have demonstrated changes in key components of sphingolipids in the kidneys under different conditions and their important roles in the renal function and the pathogenesis of various kidney diseases. This review summarizes the most recent advances in the role of sphingolipid signaling in kidney diseases.

Cerebral Small Vessel Disease: Current and Emerging Therapeutic Strategies

Cerebral small vessel disease (CSVD) is a common disease in older people, characterized by damage to intracranial microvessels, leading to cognitive decline, increased risk of stroke, and dementia. This review reviews the current therapeutic approaches for CSVD and the latest research advances, encompassing traditional pharmacological therapies, emerging targeted interventions grounded in pathophysiology, exploratory immune-related treatments, and advances in genetic research. In addition, the role of lifestyle modifications in disease management is discussed. The review emphasizes the importance of a holistic, personalized treatment strategy to improve outcomes. More clinical trials are needed to validate these treatments and optimize individualized treatment options for CSVD patients.

Ceramide synthase 6 induces mitochondrial dysfunction and apoptosis in hemin-treated neurons by impairing mitophagy through interacting with sequestosome 1

Intracerebral hemorrhage (ICH) is a severe subtype of stroke linked to high morbidity and mortality rates. However, the underlying mechanisms of neuronal injury post-ICH remain poorly understood. In this study, we investigated sphingolipid metabolism alterations in neurons using lipidomics and explored the regulatory mechanisms involved. Western blot and live-cell imaging were applied to detect mitochondrial quality and mitophagy level. We found a significant upregulation of ceramide synthase 6 (CERS6)-related C16 ceramide biosynthesis after hemin treatment. Knockdown of CERS6 notably ameliorated mitochondrial dysfunction and reduced neuronal apoptosis. Additionally, impaired neuronal mitophagy was observed after hemin treatment, which was restored by CERS6 knockdown. Mechanistically, CERS6 impaired mitophagy by interacting with sequestosome 1, leading to mitochondrial dysfunction and neuronal apoptosis. Our study explored the relationship between ceramide metabolism and mitophagy in neurons, revealing the pro-apoptotic role of CERS6 while providing a potential therapeutic target for patients with ICH.

Rat models of postintracerebral hemorrhage pneumonia induced by nasal inoculation with Klebsiella pneumoniae or intratracheal inoculation with LPS

Background

A stable and reproducible experimental bacterial pneumonia model postintracerebral hemorrhage (ICH) is necessary to help investigating the pathogenesis and novel treatments of Stroke-associated pneumonia (SAP).

Aim

To establish a Gram-negative bacterial pneumonia-complicating ICH rat model and an acute lung injury (ALI)-complicating ICH rat model.

Methods

We established two standardized models of post-ICH pneumonia by nasal inoculation with Klebsiella pneumoniae (Kp) or intratracheal inoculation with lipopolysaccharide (LPS). Survival and neurological scores were monitored. Magnetic resonance imaging was performed to evaluate hematoma volume. Abdominal aortic blood was collected for leukocyte counting, serum was isolated to determine concentrations of S100β and proinflammatory cytokines using ELISAs. Histopathological changes of brain, lung and gut were assessed using hematoxylin-eosin staining. Lung was isolated for immunofluorescence staining for myeloperoxidase (MPO). Bronchoalveolar lavage fluid was collected for leukocyte counting, and supernatant was prepared to measure MPO activity. Ileum was isolated for immunofluorescence staining for tight junction proteins ZO-1 and γδ TCRs/IL-17A and for Alcian blue-nuclear fast red staining of acidic mucins. Feces were collected, 16S rRNA sequencing, untargeted metabolomics and Spearman's correlation analyses were performed to explore changes of gut microbiota, metabolites and their interactions.

Results

In Kp-induced bacterial pneumonia-complicating ICH rats, we demonstrated that Kp challenge caused more severe neurological deficits, brain damage, neuroinflammation, and aggravated pneumonia and lung injury. Disruptions of the intestinal structure and gut barrier and the reductions of the protective intestinal IL-17A-producing γδT cells were also observed. Kp challenge exacerbated the gut microbiota dysbiosis and fecal metabolic profile disorders, which were characterized by abnormal sphingolipid metabolism especially elevated ceramide levels; increased levels of neurotoxic quinolinic acid and an upregulation of tryptophan (Trp)-serotonin-melatonin pathway. Spearman's correlation analyses further revealed that the reduction or depletion of some beneficial bacteria, such as Allobaculum and Faecalitalea, and the blooming of some opportunistic pathogens, such as Turicibacter, Dietzia, Corynebacterium and Clostridium_sensu_stricto_1 in Kp-induced SAP rats were associated with the disordered sphingolipid and Trp metabolism. Using an LPS-induced ALI complicating ICH model, we also characterized SAP-induced brain, lung and gut histopathology injuries; peripheral immune disorders and intense pulmonary inflammatory responses.

Conclusions

These two models may be highly useful for investigating the pathogenesis and screening and optimizing potential treatments for SAP. Moreover, the differential genera and sphingolipid or Trp metabolites identified above seem to be promising therapeutic targets.

New metabolic insights into the mechanism of ifosfamide encephalopathy

Ifosfamide causes neurotoxicity, including sometimes fatal encephalopathy, in a small number of patients. Why and how this occurs is not fully understood. It is generally believed that N-dechloroethylation of ifosfamide to 2-chloroacetaldehyde is the cause. A total of 61 patients were investigated, 49 who received ifosfamide and pazopanib and 12 treated with ifosfamide and sunitinib. Plasmas were analyzed by ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS) and by gas chromatography-mass spectrometry (GC-MS). Neurotoxicity occurred in 25/61 patients, including four with encephalopathy. UPLC-QTOFMS revealed that N-dechloroethylation was unlikely to be the cause but did divulge in plasma that 2-chloroethylamine, 3-phosphoserine, uridine 3'-diphosphate 5'-diphosphate, Cer(d16:1/17:0), Cer(d16:0/16:0), and thyroxine were associated with encephalopathy. GC-MS analysis showed that palmitic, oleic and stearic acids increased significantly in plasma only in nonencephalopathic patients, suggesting impaired long-chain fatty acid oxidation but an alternative metabolic pathway in encephalopathic patients. Glycine, alanine, serine, glutamate and 5-oxoproline all decreased significantly only in encephalopathic plasmas, signifying increased de novo GSH synthesis. Taken together, these findings indicate three new putative mechanisms of ifosfamide encephalopathy: (i) failure to convert 3-phosphoserine to serine due to inhibition of O-phosphoserine phosphohydratase; (ii) failure to incorporate ceramides into cerebrosides and (iii) oxidative injury of the cerebral cortex requiring de novo GSH synthesis.

Common lipidomic signatures across distinct acute brain injuries in patient outcome prediction

Lipidomic alterations have been associated with various neurological diseases. Examining temporal changes in serum lipidomic profiles, irrespective of injury type, reveals promising prognostic indicators. In this longitudinal prospective observational study, serum samples were collected early (46 ± 24 h) and late (142 ± 52 h) post-injury from 70 patients with ischemic stroke, aneurysmal subarachnoid hemorrhage, and traumatic brain injury that had outcomes dichotomized as favorable (modified Rankin Scores (mRS) 0-3) and unfavorable (mRS 4-6) three months post-injury. Lipidomic profiling of 1153 lipids, analyzed using statistical and machine learning methods, identified 153 lipids with late-stage significant outcome differences. Supervised machine learning pinpointed 12 key lipids, forming a combinatory prognostic equation with high discriminatory power (AUC 94.7 %, sensitivity 89 %, specificity 92 %; p < 0.0001). Enriched functions of the identified lipids were related to sphingolipid signaling, glycerophospholipid metabolism, and necroptosis (p < 0.05, FDR-corrected). The study underscores the dynamic nature of lipidomic profiles in acute brain injuries, emphasizing late-stage distinctions and proposing lipids as significant prognostic markers, transcending injury types. These findings advocate further exploration of lipidomic changes for a comprehensive understanding of pathobiological roles and enhanced prediction for recovery trajectories.

Fundamental Neurochemistry Review: Lipids across microglial states

The capacity of immune cells to alter their function based on their metabolism is the basis of the emerging field of immunometabolism. Microglia are the resident innate immune cells of the central nervous system, and it is a current focus of the field to investigate how alterations in their metabolism impact these cells. Microglia have the ability to utilize lipids, such as fatty acids, as energy sources, but also alterations in lipids can impact microglial form and function. Recent studies highlighting different microglial states and transcriptional signatures have highlighted modifications in lipid processing as defining these states. This review highlights these recent studies and uses these altered pathways to discuss the current understanding of lipid biology in microglia. The studies highlighted here review how lipids may alter microglial phagocytic functioning or alter their pro- and anti-inflammatory balance. These studies provide a foundation by which lipid supplementation or diet alterations could influence microglial states and function. Furthermore, targets modulating microglial lipid metabolism may provide new treatment avenues.

Elucidating of the metabolic impact of risperidone on brain microvascular endothelial cells using untargeted metabolomics-based LC-MS

Risperidone is useful for the treatment of schizophrenia symptoms; however, it also has side effects, and an overdose can be harmful. The metabolic effects of risperidone at high therapeutic doses and its metabolites have not been elucidated. Endogenous cellular metabolites may be comprehensively analyzed using untargeted metabolomics-based liquid chromatography-mass spectrometry (LC-MS), which can reveal changes in cell regulation and metabolic pathways. By identifying the metabolites and pathway changes using a nontargeted metabolomics-based LC-MS approach, we aimed to shed light on the potential toxicological effects of high-dose risperidone on brain microvascular endothelial cells (MVECs) associated with the human blood brain barrier. A total of 42 metabolites were selected as significant putative metabolites of the toxicological response of high-dose risperidone in MVECs. Six highly correlated pathways were identified, including those involving diacylglycerol, fatty acid, ceramide, glycerophospholipid, amino acid, and tricarboxylic acid metabolism. We demonstrated that methods focused on metabolomics are useful for identifying metabolites that may be used to clarify the mechanism of drug-induced toxicity.

MAMs and Mitochondrial Quality Control: Overview and Their Role in Alzheimer's Disease

Alzheimer's disease (AD) represents the most widespread neurodegenerative disorder, distinguished by a gradual onset and slow progression, presenting a substantial challenge to global public health. The mitochondrial-associated membrane (MAMs) functions as a crucial center for signal transduction and material transport between mitochondria and the endoplasmic reticulum, playing a pivotal role in various pathological mechanisms of AD. The dysregulation of mitochondrial quality control systems is considered a fundamental factor in the development of AD, leading to mitochondrial dysfunction and subsequent neurodegenerative events. Recent studies have emphasized the role of MAMs in regulating mitochondrial quality control. This review will delve into the molecular mechanisms underlying the imbalance in mitochondrial quality control in AD and provide a comprehensive overview of the role of MAMs in regulating mitochondrial quality control.

Lipidomics Analysis of Human HMC3 Microglial Cells in an In Vitro Model of Metabolic Syndrome

Metabolic endotoxemia (ME) is associated with bacterial lipopolysaccharide (LPS, endotoxin) and increased levels of saturated fatty acids (SFAs) in the bloodstream, causing systemic inflammation. ME usually accompanies obesity and a diet rich in fats, especially SFAs. Numerous studies confirm the effect of ME-related endotoxin on microglial activation. Our study aimed to assess lipid metabolism and immune response in microglia pre-stimulated with TNFα (Tumor Necrosis Factor α) and then with endotoxin and palmitic acid (PA). Using ELISA, we determined cytokines IL-1β, IL-10, IL-13 (interleukin-1β, -10, -13, and TGFβ (Transforming Growth Factor β) in the culture medium from microglial cells stimulated for 24 h with TNFα and then treated with LPS (10 ng/mL) and PA (200 µM) for 24 h. HMC3 (Human Microglial Cells clone 3) cells produced negligible amounts of IL-1β, IL-10, and IL-13 after stimulation but secreted moderate levels of TGFβ. Changes in lipid metabolism accompanied changes in TREM2 (Triggering Receptor Expressed on Myeloid Cells 2) expression. HMC3 stimulation with endotoxin increased TREM2 expression, while PA treatment decreased it. Endotoxin increased ceramide levels, while PA increased triglyceride levels. These results indicated that pre-stimulation of microglia with TNFα significantly affects its interactions with LPS and PA and modulates lipid metabolism, which may lead to microglial activation silencing and neurodegeneration.

Glycosphingolipids: from metabolism to chemoenzymatic total synthesis

GSLs are the major glycolipids in vertebrates and mediate many key biological processes from intercellular recognition to cis regulation of signal transduction. The fast-expanding field of glycobiology has led to a growing demand for diverse and structurally defined GSLs, and enzymatic GSL synthesis is developing rapidly in accordance. This article provides an overview of natural GSL biosynthetic pathways and surveys the bacterial enzymes applied to GSL synthesis and recent progress in synthesis strategies. By correlating these three areas, this article aims to define the gaps between GSL biosynthesis and chemoenzymatic synthesis and evaluate the opportunities for harnessing natural forces to access GSLs efficiently.

Circulating sphingolipids and subclinical brain pathology: the cardiovascular health study

Background

Sphingolipids are implicated in neurodegeneration and neuroinflammation. We assessed the potential role of circulating ceramides and sphingomyelins in subclinical brain pathology by investigating their association with brain magnetic resonance imaging (MRI) measures and circulating biomarkers of brain injury, neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) in the Cardiovascular Health Study (CHS), a large and intensively phenotyped cohort of older adults.

Methods

Brain MRI was offered twice to CHS participants with a mean of 5 years between scans, and results were available from both time points in 2,116 participants (mean age 76 years; 40% male; and 25% APOE ε4 allele carriers). We measured 8 ceramide and sphingomyelin species in plasma samples and examined the associations with several MRI, including worsening grades of white matter hyperintensities and ventricular size, number of brain infarcts, and measures of brain atrophy in a subset with quantitative measures. We also investigated the sphingolipid associations with serum NfL and GFAP.

Results

In the fully adjusted model, higher plasma levels of ceramides and sphingomyelins with a long (16-carbon) saturated fatty acid were associated with higher blood levels of NfL [β = 0.05, false-discovery rate corrected P (PFDR) = 0.004 and β = 0.06, PFDR = < 0.001, respectively]. In contrast, sphingomyelins with very long (20- and 22-carbon) saturated fatty acids tended to have an inverse association with levels of circulating NfL. In secondary analyses, we found an interaction between ceramide d18:1/20:0 and sex (P for interaction = <0.001), such that ceramide d18:1/20:0 associated with higher odds for infarcts in women [OR = 1.26 (95%CI: 1.07, 1.49), PFDR = 0.03]. We did not observe any associations with GFAP blood levels, white matter grade, ventricular grade, mean bilateral hippocampal volume, or total brain volume.

Conclusion

Overall, our comprehensive investigation supports the evidence that ceramides and sphingomyelins are associated with increased aging brain pathology and that the direction of association depends on the fatty acid attached to the sphingosine backbone.

Long-term intake of thermo-induced oxidized oil results in anxiety-like and depression-like behaviors: involvement of microglia and astrocytes

Frequent consumption of fried foods has been strongly associated with a higher risk of anxiety and depression, particularly among young individuals. The existing evidence has indicated that acrylamide produced from starchy foods at high temperatures can induce anxious behavior. However, there is limited research on the nerve damage caused by thermo-induced oxidized oil (TIOO). In this study, we conducted behavioral tests on mice and found that prolonged consumption of TIOO led to significant anxiety behavior and a tendency toward depression. TIOO primarily induced these two emotional disorders by affecting the differentiation of microglia, the level of inflammatory factors, the activation of astrocytes, and glutamate circulation in brain tissue. By promoting the over-differentiation of microglia into M1 microglia, TIOO disrupted their differentiation balance, resulting in an up-regulation of inflammatory factors (IL-1β, IL-6, TNF-α, NOS2) in M1 microglia and a down-regulation of neuroprotective factors IL-4/IL-10 in M2 microglia, leading to nerve damage. Moreover, TIOO activated astrocytes, accelerating their proliferation and causing GFAP precipitation, which damaged astrocytes. Meanwhile, TIOO stimulates the secretion of the BDNF and reduces the level of the glutamate receptor GLT-1 in astrocytes, leading to a disorder in the glutamate-glutamine cycle, further exacerbating nerve damage. In conclusion, this study suggests that long-term intake of thermo-induced oxidized oil can trigger symptoms of anxiety and depression.

The identification of novel stroke-related sphingolipid biomarkers using UPLC-MS/MS

BACKGROUND

Stroke is a prominent contributor to global mortality and morbidity, thus necessitating the establishment of dependable diagnostic indicators. The objective of this study was to ascertain metabolites linked to sphingolipid metabolism and assess their viability as diagnostic markers for stroke.

METHODS

Two cohorts, consisting of 56 S patients and 56 healthy volunteers, were incorporated into this investigation. Metabolite data was obtained through the utilization of Ultra Performance Liquid Chromatography and Tandem Mass Spectrometry (UPLC-MS/MS). The mass spectrometry data underwent targeted analysis and quantitative evaluation utilizing the multiple reaction monitoring mode of triple quadrupole mass spectrometry. Various data analysis techniques, including Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA), least absolute shrinkage and selection operator (LASSO) regression, Support Vector Machine (SVM), logistic regression, and Receiver Operating Characteristic (ROC) curves were employed.

RESULTS

A comprehensive analysis detected a total of 129 metabolites related to sphingolipid metabolism, encompassing ceramides, 1-phosphoceramides, phytoceramides, glycosphingolipids, sphingomyelins, and sphingomyelins. The implementation of OPLS-DA analysis revealed significant disparities between individuals with stroke and controls, as it successfully identified 31 metabolites that exhibited significant differential expression between the two groups. Furthermore, functional enrichment analysis indicated the participation of these metabolites in diverse biological processes. Six metabolic markers, namely CerP(d18:1/20:3), CerP(d18:1/18:1), CerP(d18:1/18:0), CerP(d18:1/16:0), SM(d18:1/26:1), and Cer(d18:0/20:0), were successfully validated as potential diagnostic markers for stroke. The utilization of ROC analysis further confirmed their diagnostic potential, while a logistic regression model incorporating these markers demonstrated robust efficacy in distinguishing stroke patients from healthy controls.

CONCLUSION

these identified metabolic markers exhibit clinical significance and hold promise as valuable tools for the diagnosis of stroke.