Novel Insight in Idiopathic Normal Pressure Hydrocephalus (iNPH) Biomarker Discovery in CSF.

Idiopathic normal pressure hydrocephalus (iNPH) is a potentially reversible neurological disease, causing motor and cognitive dysfunction and dementia. iNPH and Alzheimer's disease (AD) share similar molecular characteristics, including amyloid deposition, t-tau and p-tau dysregulation; however, the disease is under-diagnosed and under-treated. The aim was to identify a panel of sphingolipids and proteins in CSF to diagnose iNPH at onset compared to aged subjects with cognitive integrity (C) and AD patients by adopting multiple reaction monitoring mass spectrometry (MRM-MS) for sphingolipid quantitative assessment and advanced high-resolution liquid chromatography-tandem mass spectrometry (LC-MS/MS) for proteomic analysis. The results indicated that iNPH are characterized by an increase in very long chains Cer C22:0, Cer C24:0 and Cer C24:1 and of acute-phase proteins, immunoglobulins and complement component fragments. Proteins involved in synaptic signaling, axogenesis, including BACE1, APP, SEZ6L and SEZ6L2; secretory proteins (CHGA, SCG3 and VGF); glycosylation proteins (POMGNT1 and DAG1); and proteins involved in lipid metabolism (APOH and LCAT) were statistically lower in iNPH. In conclusion, at the disease onset, several factors contribute to maintaining cell homeostasis, and the protective role of very long chains sphingolipids counteract overexpression of amyloidogenic and neurotoxic proteins. Monitoring specific very long chain Cers will improve the early diagnosis and can promote patient follow-up.

Establishment of a Measurement System for Sphingolipids in the Cerebrospinal Fluid Based on Liquid Chromatography-Tandem Mass Spectrometry, and Its Application in the Diagnosis of Carcinomatous Meningitis.

OBJECTIVES: Sphingolipids have been demonstrated to be involved in many human diseases. However, measurement of sphingolipids, especially of sphingosine 1-phosphate (S1P) and dihydro-sphingosine 1-phosphate (dhS1P), in blood samples requires strict sampling, since blood cells easily secrete these substances during sampling and storage, making it difficult to introduce measurement of sphingolipids in clinical laboratory medicine. On the other hand, cerebrospinal fluid (CSF) contains few blood cells. Therefore, we attempted to establish a system based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the measurement of sphingolipids in the CSF, and applied it for the diagnosis of carcinomatous meningitis. METHODS: We developed and validated a LC-MS/MS-based measurement system for S1P and dhS1P and for ceramides and sphingosines, used this system to measure the levels of these sphingolipids in the CSF collected from the subjects with cancerous meningitis, and compared the levels with those in normal routine CSF samples. RESULTS: Both the measurement systems for S1P/dhS1P and for ceramides/sphingosines provided precision with the coefficient of variation below 20% for sphingolipids in the CSF samples. We also confirmed that the levels of S1P, as well as ceramides/sphingosines, in the CSF samples did not increase after the sampling. In the CSF samples collected from patients with cancerous meningitis, we observed that the ratio of S1P to ceramides/sphingosine and that of dhS1P to dihydro-sphingosine were higher than those in control samples. CONCLUSIONS: We established and validated a measurement system for sphingolipids in the CSF. The system offers promise for being introduced into clinical laboratory testing.

Biomarkers for Antidepressant Efficacy of Electroconvulsive Therapy: An Exploratory Cerebrospinal Fluid Study.

BACKGROUND: No candidate biomarkers based on cerebrospinal fluid (CSF) have been identified as prognostic factors in patients with major depression treated with electroconvulsive therapy (ECT), yet. METHOD: Following different underlying hypotheses, we analysed baseline CSF levels of markers of neurodegeneration (tau proteins, ß-amyloids and neurogranin), elements of the innate immune system (interleukin [IL]-6, neopterin, soluble CD14, soluble CD163, migration inhibitory factor and monocyte chemotactic protein 1), endocannabinoids, sphingolipids and Klotho before ECT in patients with depression (n = 12) to identify possible correlations with the clinical antidepressant response to ECT. RESULTS: Correlation with the reduction of the depressive symptoms could be observed especially for markers of neurodegeneration and elements of the innate immune system. Differences for CSF levels of several markers were found between the groups of responders and non-responders at the trend level. LIMITATIONS: The sample size is small and the -distribution of responders and non-responders is uneven. CONCLUSIONS: It is this first study on CSF biomarkers for antidepressant efficacy of ECT warrants further research regarding the mechanism of ECT and personalized antidepressant therapy.

A lipid storage-like disorder contributes to cognitive decline in HIV-infected subjects.

OBJECTIVE: In this multicenter cohort study, we sought to identify prognostic and associative metabolic indicators for HIV-associated neurocognitive disorders (HAND). METHODS: A quantitative lipidomic analysis was conducted on 524 longitudinal CSF samples collected from 7 different performance sites across the mainland United States, Hawaii, and Puerto Rico. Subjects included HIV-infected individuals with longitudinal clinical and cognitive testing data and cognitively normal HIV-negative healthy controls. RESULTS: At baseline, HIV+ subjects could be differentiated from HIV- controls by reductions in a single ceramide species and increases in multiple forms of cholesterol. Perturbations in cholesterol metabolism and ceramide were influenced by combined antiretroviral therapy (cART) use. There were no cross-sectional baseline differences in any lipid metabolite when HIV+ subjects were grouped according to cognitive status. However, a single sphingolipid metabolite and reduced levels of esterified cholesterols were prognostic indicators of incident cognitive decline. Longitudinal patterns of these disturbances in sphingolipid and sterol metabolism suggest that a progressive disorder of lipid metabolism that is similar to disorders of lipid storage may contribute to the pathogenesis of HAND. CONCLUSIONS: These findings suggest that HIV infection and cART are independently associated with a CNS metabolic disturbance, identify surrogate markers that are prognostic for cognitive decline, and implicate a lipid storage-like disorder in the progression of HAND.

Identification of Niemann-Pick C1 disease biomarkers through sphingolipid profiling.

Niemann-Pick type C (NPC)1 is a rare neurodegenerative disease for which treatment options are limited. A major barrier to development of effective treatments has been the lack of validated biomarkers to monitor disease progression or serve as outcome measures in clinical trials. Using targeted metabolomics to exploit the complex lipid storage phenotype that is the hallmark of NPC1 disease, we broadly surveyed Npc1(-/-) mouse tissues and identified elevated species across multiple sphingolipid classes that increased with disease progression. There was a striking accumulation of sphingoid bases, monohexosylceramides (MCs), and GM2 gangliosides in liver, and sphingoid bases and GM2 and GM3 gangliosides in brain. These lipids were modestly decreased following miglustat treatment, but markedly decreased in response to treatment with 2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD), two drugs that have shown efficacy in NPC1 animal models. Extending these studies to human subjects led to identification of sphingolipid classes that were significantly altered in the plasma of NPC1 patients. Plasma MCs and ceramides were elevated, whereas sphingoid bases were reduced in NPC1 subjects. Intervention with miglustat in NPC1 patients was accompanied by striking alterations in plasma (reductions in GM1 and GM3 gangliosides) and cerebrospinal fluid (CSF) (increased MCs) sphingolipids. Similar alterations were observed in the CSF from the NPC1 feline model following HP-ß-CD treatment. Our findings suggest that these lipid biomarkers may prove useful as outcome measures for monitoring efficacy of therapy in clinical trials.

Sphingosine lysolipids in the CNS: endogenous cannabinoid antagonists or a parallel pain modulatory system?

A significant number of patients experience chronic pain and the intractable side effects of currently prescribed pain medications. Recent evidence indicates important pain-modulatory roles for two classes of G-protein-coupled receptors that are activated by endogenous lipid ligands, the endocannabinoid (eCB) and sphingosine-1-phosphate (S1P) receptors, which are widely expressed in both the immune and nervous systems. In the central nervous system (CNS), CB1 cannabinoid and S1P1 receptors are most abundantly expressed and exhibit overlapping anatomical distributions and similar signaling mechanisms. The eCB system has emerged as a potential target for treatment of chronic pain, but comparatively little is known about the roles of S1P in pain regulation. Both eCB and S1P systems modulate pain perception via the central and peripheral nervous systems. In most paradigms studied, the eCB system mainly inhibits pain perception. In contrast, S1P acting peripherally at S1P1 and S1P3 receptors can enhance sensitivity to various pain stimuli or elicit spontaneous pain. However, S1P acting at S1P1 receptors and possibly other targets in the CNS can attenuate sensitivity to various pain stimuli. Interestingly, other endogenous sphingolipid derivatives might play a role in central pain sensitization. Moreover, these sphingolipids can also act as CB1 cannabinoid receptor antagonists, but the physiological relevance of this interaction is unknown. Overall, both eCB and sphingolipid systems offer promising targets for the treatment of chronic pain. This review compares and contrasts the eCB and S1P systems with a focus on their roles in pain modulation, and considers possible points of interaction between these systems.

Changes in the cerebrospinal fluid ceramide profile after subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: The purpose of this study was to investigate changes in the cerebrospinal fluid sphingolipid profile in patients with subarachnoid hemorrhage in relation to the occurrence of symptomatic vasospasm and outcome at hospital discharge. METHODS: The ceramide profile in the cerebrospinal fluid was determined by mass spectrometry in control subjects and patients with Fisher 3 grade subarachnoid hemorrhage within 48 hours of the bleed. Patients were prospectively followed and subcategorized based on the occurrence of symptomatic vasospasm and modified Rankin Scale at discharge. RESULTS: Compared to control subjects, patients with subarachnoid hemorrhage had higher cerebrospinal fluid levels of total ceramide (12.4±8.8 versus 54.6±49.3 pmol/mL; P<0.001). In the subgroup analysis, total ceramide levels in individuals with symptomatic vasospasm (104.2±57.0 pmol/mL) were higher than in those with asymptomatic vasospasm (32.4±25.7 pmol/mL; P=0.006) and no vasospasm (30.9±15.7 pmol/mL; P=0.003). In addition, compared to patients with a good outcome (modified Rankin Scale ≤3), individuals with poor outcome (modified Rankin Scale ≥4) had higher cerebrospinal fluid levels of total ceramide (79±25 versus 23±6 pmol/mL; P=0.008). When the relative contributions of the different ceramide species were calculated, a higher relative concentration of C(18:0) ceramide was observed in individuals with symptomatic vasospasm (P=0.018) and poor outcome (P=0.028). CONCLUSIONS: Ceramide profile changes occur in subarachnoid hemorrhage. In this small case-based series elevation of levels of this sphingolipid, particularly C(18:0), was associated with the occurrence of symptomatic vasospasm and poor neurological outcome after subarachnoid hemorrhage.

Disturbance in cerebral spinal fluid sphingolipid content is associated with memory impairment in subjects infected with the human immunodeficiency virus.

Despite widespread use of antiretroviral therapies to control replication of the human immunodeficiency virus (HIV), dysfunctions of cognition that are collectively termed HIV-associated neurocognitive disorders (HAND) still occur in approximately 50% of those infected by the virus. Currently there is not a biomarker that can identify HIV-infected people who are at risk for the development of HAND. Previous studies have identified particular sphingolipid species that are dysregulated in HAND, but the neurocognitive correlates of these biochemical findings are not currently understood. To address this question, we compared cerebrospinal fluid (CSF) levels of sphingomyelin, ceramide, and sterol species with performance on standard neurological tests designed to assess the function of multiple cognitive and motor domains in HIV-infected subjects. We found that sphingomyelin:ceramide ratios for acyl chain lengths of C16:0, C18:0, C22:0, and C24:0 were associated with worse performance on several indices of memory. The most striking finding was for the acyl chain of C18:0 that consistently associated with performance on multiple tests of memory. These findings suggest that the sphingomyelin:ceramide ratio for C18:0 may be a reasonable surrogate marker for memory dysfunction in HIV-infected subjects.

Associative and predictive biomarkers of dementia in HIV-1-infected patients.

BACKGROUND: Infection with HIV can result in a debilitating CNS disorder known as HIV dementia (HIV-D). Since the advent of highly active antiretroviral therapy (HAART), the incidence of HIV-D has declined, but the prevalence continues to increase. In this new era of HIV-D, traditional biomarkers such as CSF viral load and monocyte chemotactic protein 1 levels are less likely to be associated with dementia in patients on HAART and biomarkers that can predict HIV-D have not yet been identified. OBJECTIVE: To identify biomarkers that are associated with and can predict HIV-D. METHODS: We grouped patients with HIV based on changes in cognitive status over a 1-year period and analyzed sphingolipid, sterol, triglyceride, antioxidant, and lipid peroxidation levels in CSF. RESULTS: We found that increased levels of the vitamin E and triglyceride C52 predicted the onset or worsening of dementia. Elevated levels of sphingomyelin were associated with inactive dementia. Elevated levels of ceramide and the accumulation of 4-hydroxynonenals were associated with active dementia. CONCLUSIONS: We interpret these findings to indicate that early in the pathogenesis of HIV dementia, there is an up-regulation of endogenous antioxidant defenses in brain. The failure of this attempted neuroprotective mechanism leads to the accumulation of sphingomyelin and moderate cognitive dysfunction. The breakdown of this enlarged pool of sphingomyelin to ceramide and the accumulation of highly reactive aldehydes are associated with declining cognitive function. Thus, elevations in endogenous protective mechanisms may identify patients who are at increased risk of the development of HIV dementia.

Cerebrospinal fluid lipids in demyelinating disease. I. Sphingolipids.

The lipid composition of CSF, serum and lymphocytes from patients without demyelinating disease (controls) as well as from patients with acute and chronic MS is analyzed. Individual lipid fractions are isolated by TLC and their fatty acid composition determined. Lipid and fatty acid composition of normal CSF resembles the results found in lymphocytes and it is deduced that CSF lipids are derived mainly from lymphocytes rather than white matter (myelin) or serum. There is an increase of CSF sphingomyelin in patients with acute MS (showing pleocytosis) which is apparently derived from disintegrated lymphocytes; there is also an increase of linoleic acid concentration which could come from serum because of dysfunction of the blood-brain barrier. The role of the CNS in contributing to CSF lipids is considered negligible both in controls and in patients with demyelination.