Proteomic analysis of cerebrospinal fluid of amyotrophic lateral sclerosis patients in the presence of autologous bone marrow derived mesenchymal stem cells.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a fatal and rapidly progressive motoneuron degenerative disorder. There are still no drugs capable of slowing disease evolution or improving life quality of ALS patients. Thus, autologous stem cell therapy has emerged as an alternative treatment regime to be investigated in clinical ALS. METHOD: Using Proteomics and Protein-Protein Interaction Network analyses combined with bioinformatics, the possible cellular mechanisms and molecular targets related to mesenchymal stem cells (MSCs, 1 × 106 cells/kg, intrathecally in the lumbar region of the spine) were investigated in cerebrospinal fluid (CSF) of ALS patients who received intrathecal infusions of autologous bone marrow-derived MSCs thirty days after cell therapy. Data are available via ProteomeXchange with identifier PXD053129. RESULTS: Proteomics revealed 220 deregulated proteins in CSF of ALS subjects treated with MSCs compared to CSF collected from the same patients prior to MSCs infusion. Bioinformatics enriched analyses highlighted events of Extracellular matrix and Cell adhesion molecules as well as related key targets APOA1, APOE, APP, C4A, C5, FGA, FGB, FGG and PLG in the CSF of cell treated ALS subjects. CONCLUSIONS: Extracellular matrix and cell adhesion molecules as well as their related highlighted components have emerged as key targets of autologous MSCs in CSF of ALS patients. TRIAL REGISTRATION: Clinicaltrial.gov identifier NCT0291768. Registered 28 September 2016.

The LXR agonist GW3965 increases apoA-I protein levels in the central nervous system independent of ABCA1.

Lipoprotein metabolism in the central nervous system (CNS) is based on high-density lipoprotein-like particles that use apoE as their predominant apolipoprotein rather than apoA-I. Although apoA-I is not expressed in astrocytes and microglia, which produce CNS apoE, apoA-I is reported to be expressed in porcine brain capillary endothelial cells and also crosses the blood-brain barrier (BBB). These mechanisms allow apoA-I to reach concentrations in cerebrospinal fluid (CSF) that are approximately 0.5% of its plasma levels. Recently, apoA-I has been shown to enhance cognitive function and reduce cerebrovascular amyloid deposition in Alzheimer's Disease (AD) mice, raising questions about the regulation and function of apoA-I in the CNS. Peripheral apoA-I metabolism is highly influenced by ABCA1, but less is known about how ABCA1 regulates CNS apoA-I. We report that ABCA1 deficiency leads to greater retention of apoA-I in the CNS than in the periphery. Additionally, treatment of symptomatic AD mice with GW3965, an LXR agonist that stimulates ABCA1 expression, increases apoA-I more dramatically in the CNS compared to the periphery. Furthermore, GW3965-mediated up-regulation of CNS apoA-I is independent of ABCA1. Our results suggest that apoA-I may be regulated by distinct mechanisms on either side of the BBB and that apoA-I may serve to integrate peripheral and CNS lipid metabolism. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).

Apolipoprotein A-I in mouse cerebrospinal fluid derives from the liver and intestine via plasma high-density lipoproteins assembled by ABCA1 and LCAT.

Apolipoprotein (apo) A-I, the major structural protein of high-density lipoprotein (HDL), is present in human and mouse cerebrospinal fluid (CSF) despite its lack of expression in brain cells. To identify the origin of apoA-I in CSF, we generated intestine-specific and liver-specific Apoa1 knockout mice (Apoa1ΔInt and Apoa1Δliv mice, respectively). Lipoprotein profiles of Apoa1ΔInt and Apoa1ΔLiv mice resembled those of control littermates, whereas knockout of Apoa1 in both intestine and liver (Apoa1ΔIntΔLiv ) resulted in a 60-percent decrease in HDL-cholesterol levels, thus strongly mimicking the Apoa1-/- mice. Immunoassays revealed that mouse apoA-I was not present in the CSF of the Apoa1ΔIntΔLiv mice. Furthermore, apoA-I levels in CSF were highly correlated with plasma spherical HDL levels, which were regulated by ABCA1 and LCAT. Collectively, these results suggest that apoA-I protein in CSF originates in liver and small intestine and is taken up from the plasma.

Tetranectin and apolipoprotein A-I in cerebrospinal fluid as potential biomarkers for Parkinson's disease.

OBJECTIVE: The application of biomarkers may potentially improve the efficiency of the diagnosis for Parkinson's disease (PD). However, no reliable biomarker has been identified to date. This study is aimed to identify proteins that might serve as potential biomarkers for PD diagnosis or pathogenesis. MATERIALS AND METHODS: Two-dimensional difference gel electrophoresis (2D DIGE) technique, in combination with matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS), was used to determine the differentially expressed cerebrospinal fluid (CSF) proteins in PD patients (n = 3) compared with normal controls (n = 3). Selected proteins were further confirmed by Western blotting analysis in the CSF of PD patients (n = 8), Alzheimer's disease (AD) patients (n = 6) and normal control subjects (n = 7). RESULTS: Eight proteins were identified after MS and protein database interrogation. In the CSF of PD patients, the expression levels of one isoform of apolipoprotein A-I (apoA-I), tetranectin, myosin phosphatase target subunit 1 (MYPT1), and two unknown proteins were down-regulated, whereas the expression levels of another apoA-I isoform, proapolipoprotein, and lipoprotein were up-regulated. Western blotting indicates that the expression of tetranectin was reduced in the CSF from PD patients and elevated in AD, while the expression of apoA-I was changed only in the CSF from PD patients. CONCLUSION: Our preliminary results suggest that tetranectin and apoA-I may serve as potential biomarkers for PD, though further validation is needed.

Proteomics-derived cerebrospinal fluid markers of autopsy-confirmed Alzheimer's disease.

The diagnostic performance of several candidate cerebrospinal fluid (CSF) protein biomarkers in neuropathologically confirmed Alzheimer's disease (AD), non-demented (ND) elderly controls and non-AD dementias (NADD) was assessed. Candidate markers were selected on the basis of initial two-dimensional gel electrophoresis studies or by literature review. Markers selected by the former method included apolipoprotein A-1 (ApoA1), haemopexin (HPX), transthyretin (TTR) and pigment epithelium-derived factor (PEDF), while markers identified from the literature included Abeta1-40, Abeta1-42, total tau, phosphorylated tau, alpha-1 acid glycoprotein (A1GP), haptoglobin, zinc alpha-2 glycoprotein (Z2GP) and apolipoprotein E (ApoE). Ventricular CSF concentrations of the markers were measured by enzyme-linked immunosorbent assay (ELISA). The concentrations of Abeta1-42, ApoA1, A1GP, ApoE, HPX and Z2GP differed significantly among AD, ND and NADD subjects. Logistic regression analysis for the diagnostic discrimination of AD from ND found that Abeta1-42, ApoA1 and HPX each had significant and independent associations with diagnosis. The CSF concentrations of these three markers distinguished AD from ND subjects with 84% sensitivity and 72% specificity, with 78% of subjects correctly classified. By comparison, using Abeta1-42 alone gave 79% sensitivity and 61% specificity, with 68% of subjects correctly classified. For the diagnostic discrimination of AD from NADD, only the concentration of Abeta1-42 was significantly related to diagnosis, with a sensitivity of 58%, specificity of 86% and 86% correctly classified. The results indicate that for the discrimination of AD from ND control subjects, measurement of a set of markers including Abeta1-42, ApoA1 and HPX improved diagnostic performance over that obtained by measurement of Abeta1-42 alone. For the discrimination of AD from NADD subjects, measurement of Abeta1-42 alone was superior.

ApoE and clusterin CSF levels influence associations between APOE genotype and changes in CSF tau, but not CSF Aß42, levels in non-demented elderly.

Apolipoprotein E (APOE) ε4 genotype is associated with increased cerebral amyloid beta (Aß) deposition in nondemented elderly and suggested to influence ApoE as well as ApoJ (clusterin [Clu]) and ApoA1 expression. We aimed to assess whether APOE affects early Alzheimer's disease pathophysiology via these apolipoproteins. Cerebrospinal fluid (CSF) ApoE, Clu, ApoA1, and CSF amyloid beta1-42 (Aß42) and tau levels were assessed in 403 individuals with subjective cognitive decline and mild cognitive impairment using enzyme-linked immunosorbent assay. Whether CSF apolipoprotein levels mediated APOEε4 allele frequency effects on CSF Aß42 and tau in nondemented elderly was investigated using mediation analysis, with age- and gender-adjusted linear regression analyses. CSF ApoE mediated 48% of the association between APOEε4 and CSF tau, whereas Clu and ApoA1 did not. In addition, CSF Clu partially mediated the relation between CSF ApoE and tau (12%). CSF apolipoproteins did not mediate the inverse relation between APOEε4 and CSF Aß42, despite a strong association between the latter 2 biomarkers. In summary, our findings suggest that ApoE and Clu are involved in Aß-independent pathways as part of the cascade leading to Alzheimer pathology.

CSF proteome analysis in multiple sclerosis patients by two-dimensional electrophoresis.

BACKGROUND AND PURPOSE: In recent years, different approaches have been used to investigate changes of cerebrospinal fluid (CSF) proteome in patients affected by multiple sclerosis (MS) with the aim to identify protein markers with potential diagnostic or prognostic value. Because of the lack of standardization of current proteomic techniques, contrasting results were achieved until now in different laboratories. In this study, we compare CSF proteome of 10 relapsing-remitting MS (RR-MS) patients, 11 patients with clinically isolated syndrome (CIS), and 10 control subjects without neurological or systemic diseases. METHODS: The differential expression of CSF proteins amongst these cohorts of patients was investigated by using two-dimensional electrophoresis and mass spectrometry. RESULTS AND CONCLUSIONS: We found an overexpression of IgG free kappa light chain protein in both CIS and RR-MS patients, compared with control subjects and an increased expression of an apolipoprotein E isoform in RR-MS patients, compared with CIS and control groups. Our results confirm the presence of CSF proteome changes in MS patients. Future research should be aimed to investigate the role of these candidate CSF markers in larger cohorts of CIS and MS patients.

Reduced Cerebrospinal Fluid Concentration of Apolipoprotein A-I in Patients with Alzheimer's Disease.

BACKGROUND: Apolipoprotein E (ApoE) has been extensively studied in Alzheimer's disease (AD), but little is known of apolipoprotein A-I (ApoA-I) in cerebrospinal fluid (CSF). OBJECTIVE: Plasma lipids as well as ApoA-I and ApoE in plasma and CSF were determined and related to Mini-Mental State Examination (MMSE) score, APOE genotype, and CSF AD biomarkers. METHODS: Consecutive patients with AD (n = 29), stable mild cognitive impairment (n = 13), other dementias (n = 14), and healthy controls (n = 18) were included at a single center. RESULTS: AD patients had higher plasma triglycerides and lower CSF ApoA-I concentration than controls (both p < 0.05). CSF ApoE concentration was reduced in other dementias (p < 0.01). In AD as well as other dementias, the ratios between CSF and plasma concentrations of both ApoA-I and ApoE were lower than those in the controls. ApoA-I and ApoE in plasma and CSF were not influenced by APOEɛ4 allele distribution. In the total study population (n = 74), CSF ApoA-I correlated positively with MMSE score (r = 0.26, p < 0.05) and negatively with CSF P-tau (r = -0.25, p < 0.05). CSF ApoE correlated positively with CSF concentrations of T-tau and P-tau in the total study population and in AD patients. CONCLUSION: CSF ApoA-I was reduced in AD patients and associated with measures of cognitive function and AD disease status. The mechanisms underlying the decreased CSF:plasma ratios of ApoA-I and ApoE in AD and other dementias need to be explored in further studies.

Apolipoprotein A1 in Cerebrospinal Fluid and Plasma and Progression to Alzheimer's Disease in Non-Demented Elderly.

BACKGROUND: HDL-cholesterol transporter Apolipoprotein A1 (ApoA1) holds neuroprotective properties, such as inhibition of amyloid-ß aggregation. Low plasma ApoA1 concentrations are associated with Alzheimer's disease (AD). Little is known about ApoA1 levels in the pre-dementia stages of AD. OBJECTIVE: To investigate associations between cerebrospinal fluid (CSF) and plasma ApoA1 levels and clinical progression toward AD in non-demented elderly. METHODS: From the Amsterdam Dementia Cohort, we included 429 non-demented elderly with subjective cognitive decline (SCD; n = 206, 61±9 years, Mini-Mental State Exam (MMSE) 28±2) and mild cognitive impairment (MCI; n = 223, 67±8 years, MMSE 27±2), with a mean follow-up of 2.5±1.6 years. We used Cox proportional hazard models to investigate relations between CSF and plasma ApoA1 concentrations and clinical progression, defined as progression to MCI or AD for SCD, and progression to AD for MCI. Analyses were adjusted for age, gender, MMSE, and plasma cholesterol levels. Analyses were stratified for diagnosis and APOEɛ4 carriership. RESULTS: 117 patients (27%) showed clinical progression. One standard deviation increase of CSF ApoA1 was associated with a 30% increased risk of clinical progression (hazard ratio (HR) (95% CI)  = 1.3(1.0-1.6)). The effect appeared to be attributable to the APOEɛ4 carriers with SCD (HR 3.3(1.0-10.9)). Lower plasma ApoA1 levels were associated with an increased risk of clinical progression in APOEɛ4 carriers with SCD (HR 5.0(1.3-18.9)). CONCLUSION: Higher CSF and lower plasma ApoA1 levels were associated with an increased risk of clinical progression in APOEɛ4 carriers with SCD; suggesting that ApoA1 may be involved in the earliest stages of AD.

Protein signature in cerebrospinal fluid and serum of Alzheimer's disease patients: The case of apolipoprotein A-1 proteoforms.

In the diagnosis of Alzheimer's disease (AD) total tau (T-tau), tau phosphorylated at threonine 181 (P-tau181), and the 42 amino acid isoform of alpha ß-amyloid (Aß) are well established surrogate CSF markers. However, there is a constant need for new diagnostic markers to identify the disease at a very early stage. The identification of new molecules for AD diagnosis and monitoring in CSF is hampered by several "confounding" factors including intra- and inter-individual, pre-analytical and analytical variabilities. In an attempt to partially overcome patient's variability and to determine new molecules significantly dysregulated in CSF, we assessed the proteome profile of low molecular weight protein species in CSF and serum of the same patients. CSFs and sera from 36 ADs, 32 iNPHs (idiopathic normal pressure hydrocephalus) and 12 controls were compared by MALDI profiling (non-parametric statistics, CV<20%, AUC>0.750). After protein identification by mass spectrometry, the proteoform composition was assessed by 2-D DIGE/MS. Results indicated that CSF of iNPH can be used as control. Serum and CSF of AD patients shows a specific protein profile compared to iNPH samples. A variation (p<0.01) of Apo A-1 levels in AD, together with a specific dysregulation of Apo A-1 proteoforms was observed. The profiling of CSF and serum of the same patients, suggests that the decrement of total Apo A-1 occurs specifically in CSF. Serum and CSF of AD shows a characteristic Apo A-1 proteoform pattern suggesting it as potential marker which can support the clinical workflow adopted for AD diagnosis and progression.

Comparative proteomics of cerebrospinal fluid in neuropathologically-confirmed Alzheimer's disease and non-demented elderly subjects.

OBJECTIVES: Diagnostic tests able to reveal Alzheimer's disease (AD) in living patients before cognitive ability is destroyed are urgently needed. Such tests must distinguish AD from other dementia causes, as well as differentiate subtle changes associated with normal aging from true pathology emergence. A single biomarker offering such diagnostic and prognostic capacities has eluded identification. Therefore, a valuable test for AD is likely to be based on a specific pattern of change in a set of proteins, rather than a single protein. METHODS: We examined pooled cerebrospinal fluid (CSF) samples obtained from neuropathologically-confirmed AD (n=43) and non-demented control subjects (n=43) using 2-dimensional gel electrophoresis (2DE) proteomic methodology to detect differentially expressed proteins. Proteins exhibiting expression level differences between the pools were recovered and identified using matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry. RESULTS: Five differentially-expressed proteins with potential roles in amyloid-beta metabolism and vascular and brain physiology [apolipoprotein A-1 (Apo A-1), cathepsin D (CatD), hemopexin (HPX), transthyretin (TTR), and two pigment epithelium-derived factor (PEDF) isoforms] were identified. Apo A-1, CatD and TTR were significantly reduced in the AD pool sample, while HPX and the PEDF isoforms were increased in AD CSF. DISCUSSION: These results suggest that multi-factor proteomic pattern analysis of the CSF may provide a means to diagnose and assess AD.

Remodelling of cerebrospinal fluid lipoproteins after subarachnoid hemorrhage.

Lipoprotein particles (Lps) in normal human cerebrospinal fluid (CSF) are distinct from those found in plasma and include unique apolipoprotein E (apoE indicates protein; APOE, gene) containing lipoproteins rarely seen in human plasma. Less favourable neurological recovery after subarachnoid hemorrhage (SAH) has been observed in patients who possess the APOE epsilon4 allele raising the possibility that apoE influences neuronal survival after brain injury. We analysed Lps from control and SAH CSF testing the hypotheses that following brain injury CSF Lps undergo remodelling and apoE containing Lps are selectively depleted from brain injury CSF. Lipoproteins were fractionated using CSF from six control pools and six patients with SAH on a sepharose 6HR 10/30 size exclusion column. Fractions were assayed for total cholesterol (TC), free cholesterol (FC), phospholipid, triglyceride (TG), apoE, apolipoprotein B (apoB), and apolipoprotein AI (apoAI). Compared to control CSF there were significant (P<0.05) increases in TC, FC, TG, and apoAI in SAH CSF. Plasma sized apoB-containing lipoproteins and a very small apoAI-containing Lps were identified in the SAH CSF, which were not present in controls. However, despite the release of plasma lipoproteins into the subarachnoid space, there was no significant increase in CSF apoE. These data provide novel indirect evidence suggesting that after SAH CSF Lps undergo remodelling and apoE containing Lps are selectively reduced in brain injury CSF. The remodelling of CSF Lps and selective reduction of apoE containing lipoproteins may reflect an important response of the human brain to injury.

Remodeling of cerebrospinal fluid lipoprotein particles after human traumatic brain injury.

The association between possession of the APOE epsilon4 allele and unfavourable outcome after traumatic brain injury (TBI) suggests that the apolipoprotein E protein (apoE) plays a key role in the response of the human brain to injury. ApoE is known to regulate cholesterol metabolism in the periphery through its action as a ligand for receptor mediated uptake of lipoprotein particles (Lps). Greater understanding of cholesterol metabolism in the human central nervous system may identify novel treatment strategies applicable to acute brain injury. We report findings from the analysis of lipoproteins in the cerebrospinal fluid (CSF) of patients with TBI and non-injured controls, testing the hypothesis that remodeling of CSF lipoproteins reflects the response of the brain to TBI. CSF Lps were isolated from the CSF of controls and patients with severe TBI by size exclusion chromatography, and the lipoprotein fractions analysed for cholesterol, phospholipid, apoAI, and apoE. There was a marked decrease in apoE containing Lps in the TBI CSF compared to controls (p=0.002). After TBI there was no significant decrease in apoAI containing CSF Lps (CSF LpAI), but the apoAI resided on smaller sized particles than in control CSF. There was a population of very small sized Lps in TBI CSF, which were associated with the increased cholesterol (p=0.0001) and phospholipid (p=0.040) seen after TBI. The dramatic loss of apoE containing Lps from the CSF, and the substantial increase in CSF cholesterol, support the concept that apoE and cholesterol metabolism are intimately linked in the context of acute brain injury. Treatment strategies targeting CNS lipid transport, required for neuronal sprouting and synaptogenesis, may be applicable to traumatic brain injury.

Cerebrospinal fluid apo E and apo A-I concentrations in early- and late-onset Alzheimer's disease.

We compared cerebrospinal fluid (CSF) apolipoprotein (apo) A-I and apo E concentrations in early- and late-onset Alzheimer's disease (EOAD (n = 11), LOAD (n = 15), respectively) with those in control subjects (n = 23). CSF apo A-I levels in both EOAD and LOAD were consistent with control subjects. However, CSF apo E levels were significantly lower in EOAD group (mean +/- SD; 2.65 +/- 1.69 mg/l, P < 0.05) and higher in LOAD group (5.90 +/- 1.94 mg/l, P < 0.01) than those in control group (4.16 +/- 1.69 mg/l). In addition, the epsilon4 allele frequency was not different between EOAD and LOAD groups. Although the reason for the difference in CSF apo E concentrations between two groups is unknown, CSF apo E concentration seems to be associated with the pathogenesis of EOAD and LOAD. The rate of apo E production and/or catabolism in the brain may be different between them.

Apo A-I and apo E concentrations in cerebrospinal fluids of patients with acute meningitis.

It has been demonstrated that apolipoproteins found in cerebrospinal fluid (CSF) play an important role in lipid metabolism in the central nervous system (CNS). Previously we reported that CSF apo A-I levels increased with the severity of neurological damage in poliovirus-infected macaques. In the present study, apo A-I was quantitatively analysed in CSF from patients with or without neurological diseases. In controls, CSF apo A-I level was significantly higher in males; 3.83 (0.40) mg/L, mean (SEM) (n = 19) compared with females, 2.42 (0.26) mg/L (n = 23, P < 0.05). CSF apo A-I concentrations in patients with acute meningitis increased at the active stage, 7.74 (1.78) mg/L (n = 10), but returned to basal concentrations at the convalescent stage 2.72 (0.38) mg/L (n = 10), while the CSF apo A-I level in patients with other neurological diseases remained in the same range as in controls. By contrast, CSF apo E was consistently elevated at either stage of acute meningitis. Furthermore, it was found that the levels of CSF apo A-I, but not of apo E, correlated positively with CSF albumin concentrations. These findings suggest that the CSF apo A-I and apo E have different origins and may play different roles in the lipoprotein metabolism in CNS.

Microsequencing of bovine cerebrospinal fluid apolipoproteins: identification of bovine apolipoprotein E.

In studies of bovine plasma lipoproteins, apolipoprotein E (apoE) was not found associated with alpha-lipoproteins isolated over a broad range of densities. However, studies of cerebrospinal fluid (CSF) lipoproteins from other mammals have shown that apoE is a major apolipoprotein associated with high density lipoprotein, a fact that prompted us to determine if this were also the case in bovine CSF. CSF samples were obtained from animals with a surgically implanted catheter. Most analyzed samples were obtained from cows at various stages of the postpartum period; however, a few samples also were obtained at term or during pregnancy. Analyses of isolated ultracentrifugal fractions by polyacrylamide gel electrophoresis revealed the presence of two apo, with the expected molecular weights for apoE and apoA-I. By using both matrix-assisted laser desorption mass spectrometry and microsequencing techniques, we demonstrated that these apo are indeed apoE and apoA-I.

Predominant apolipoprotein J exists as lipid-poor mixtures in cerebrospinal fluid.

Apolipoprotein (apo) J, abundant in cerebrospinal fluid (CSF), is known to play a role in the pathogenesis of Alzheimer's disease (AD); however, the mechanism remains obscure. To characterize the apoJ-containing lipoproteins in CSF, we compared the distribution of apoJ in CSF lipoprotein partides with those of apoE and apoAI. CSF lipoproteins (fractionated by ultracentrifugation, gel-filtration chromatography, and agarose-gel electrophoresis) were characterized by immunoblot analysis using anti-apoJ, anti-apoE, and anti-apoAI antibodies. Immunoprecipitation and immunoabsorption were used to clarify the combinations in which these apolipoproteins exist. All of the apoJ in CSF was in the fraction with density of > or = 1.250 g/ml after ultracentrifugation; relatively little apoE and apoAI was in that fraction. In gel-filtration chromatography, the main peak of apoJ-containing lipoprotein particles was clearly distinguishable from those of apoE- and apoAI-containing lipoproteins. Immunoabsorption and agarose-gel electrophoresis indicated that the dominant apoJ-containing lipoprotein partides did not contain apoE. These findings indicate that a significant fraction of the apoJ present in CSF does not co-exist with apoE or apoAI within the same particles. Immunoprecipitation revealed two types of particles: one that contains no apoAl but apoE and another that contains no apoE but apoAI. These results show that several subfractions of lipoprotein particles exist in CSF, differing from each other in their combinations of apoE, apoJ, and apoAI. We concluded that there are at least 9 forms or combinations (including free apolipoproteins) of apoJ, apoE, and apoAl in the CSF.

Characterization of lipoproteins in cerebrospinal fluid of mares during pregnancy and lactation.

OBJECTIVE: To measure apolipoproteins in cerebrospinal fluid (CSF) from healthy mares and to determine whether CSF concentrations of apolipoproteins change during pregnancy and lactation. ANIMALS: 5 healthy pregnant mares. PROCEDURE: 2 sets of CSF samples were obtained; initial samples were obtained 10 to 30 days before parturition (mean, 18 days; median, 17 days), and second samples were obtained 19 to 26 days after parturition (mean, 23 days; median, 23 days). Cerebrospinal fluid was collected from the lumbosacral subarachnoid space of standing horses by use of routine collection techniques. Cerebrospinal fluid cholesterol concentrations were measured by use of a sensitive enzymatic assay. Ultracentrifugal fractions of CSF lipoproteins were characterized by determining the distribution of apolipoproteins, using polyacrylamide gel electrophoresis. RESULTS: Analyses of isolated ultracentrifugal fractions by polyacrylamide gel electrophoresis revealed 2 apolipoproteins, with the expected molecular weights for apolipoprotein E and apolipoprotein A-I. No significant differences were observed between pre- and postpartum values in mares. The concentration of cholesterol in CSF fluid of mares was comparable to values reported in other mammals. CONCLUSIONS AND CLINICAL RELEVANCE: Apolipoprotein E in CSF of horses is a major apolipoprotein associated with high-density lipoproteins, which is similar to findings in other mammals. Additional characterization of the role of apolipoproteins in mammalian CSF may provide critical insight into various degenerative neurologic disease processes.

Levels of apolipoprotein A-II in cerebrospinal fluid in patients with neuroborreliosis are associated with lipophagocytosis.

Levels of most of the examined proteins in cerebrospinal fluid (CSF) of 107 patients with neuroborreliosis were associated with cytological findings, the status of hematoencephalic barrier as evaluated by Qalb (cerebrospinal fluid to serum quotient) and the intrathecal synthesis of immunoglobulins. Cytological findings consisted of normal cytology, or both oligocytosis and pleocytosis of monocytes or lymphocytes. The lipophagic elements were present in 20% of samples. Concentrations of apolipoproteins A-I and A-II in the CSF were correlated with the concentration of albumin without regard to the CSF cytology. The levels of apolipoprotein B were increased only in samples with lymphocytic pleocytosis and Qalb > 7.4. The presence of lipophages in the CSF was significantly associated with the CSF concentration of apolipoprotein A-II.

Intravenously injected human apolipoprotein A-I rapidly enters the central nervous system via the choroid plexus.

BACKGROUND: Brain lipoprotein metabolism is dependent on lipoprotein particles that resemble plasma high-density lipoproteins but that contain apolipoprotein (apo) E rather than apoA-I as their primary protein component. Astrocytes and microglia secrete apoE but not apoA-I; however, apoA-I is detectable in both cerebrospinal fluid and brain tissue lysates. The route by which plasma apoA-I enters the central nervous system is unknown. METHODS AND RESULTS: Steady-state levels of murine apoA-I in cerebrospinal fluid and interstitial fluid are 0.664 and 0.120 µg/mL, respectively, whereas brain tissue apoA-I is ≈10% to 15% of its levels in liver. Recombinant, fluorescently tagged human apoA-I injected intravenously into mice localizes to the choroid plexus within 30 minutes and accumulates in a saturable, dose-dependent manner in the brain. Recombinant, fluorescently tagged human apoA-I accumulates in the brain for 2 hours, after which it is eliminated with a half-life of 10.3 hours. In vitro, human apoA-I is specifically bound, internalized, and transported across confluent monolayers of primary human choroid plexus epithelial cells and brain microvascular endothelial cells. CONCLUSIONS: Following intravenous injection, recombinant human apoA-I rapidly localizes predominantly to the choroid plexus. Because apoA-I mRNA is undetectable in murine brain, our results suggest that plasma apoA-I, which is secreted from the liver and intestine, gains access to the central nervous system primarily by crossing the blood-cerebrospinal fluid barrier via specific cellular mediated transport, although transport across the blood-brain barrier may also contribute to a lesser extent.