The Role of CSF Transthyretin in Human Alzheimer's Disease: Offense, Defense, or not so Innocent Bystander.

Transthyretin (TTR) is secreted by hepatocytes, retinal pigment epithelial cells, pancreatic α and ß cells, choroid plexus epithelium, and neurons under stress. The choroid plexus product is the main transporter of the thyroid hormone thyroxine (T4) to the brain during early development. TTR is one of three relatively abundant cerebrospinal fluid (CSF) proteins (Apolipoprotein J [ApoJ] (also known as clusterin), Apolipoprotein E [ApoE], and TTR) that interact with Aß peptides in vitro, in some instances inhibiting their aggregation and toxicity. It is now clear that clusterin functions as an extracellular, and perhaps intracellular, chaperone for many misfolded proteins and that variation in its gene (Clu) is associated with susceptibility to sporadic Alzheimer's disease (AD). The function of ApoE in AD is not yet completely understood, although the ApoE4 allele has the strongest genetic association with the development of sporadic late onset AD. Despite in vitro and in vivo evidence of the interaction between TTR and Aß, genomewide association studies including large numbers of sporadic Alzheimer's disease patients have failed to show significant association between variation in the TTR gene and disease prevalence. Early clinical studies suggested an inverse relationship between CSF TTR levels and AD and the possibility of using the reduced CSF TTR concentration as a biomarker. Later, more extensive analyses indicated that CSF TTR concentrations may be increased in some patients with AD. While the observed changes in TTR may be pathogenetically or biologically interesting because of the inconsistency and lack of specificity, they offered no benefit diagnostically or prognostically either independently or when added to currently employed CSF biomarkers, i.e., decreased Aß1-42 and increased Tau and phospho-Tau. While some clinical data suggest that increases in CSF TTR may occur early in the disease with a significant decrease late in the course, without additional, more granular data, CSF TTR changes are neither consistent nor specific enough to warrant their use as a specific AD biomarker.

The Role of Transthyretin in Oligodendrocyte Development.

Transthyretin (TTR) is a protein that binds and distributes thyroid hormones (THs) in blood and cerebrospinal fluid. Previously, two reports identified TTR null mice as hypothyroid in the central nervous system (CNS). This prompted our investigations into developmentally regulated TH-dependent processes in brains of wildtype and TTR null mice. Despite logical expectations of a hypomyelinating phenotype in the CNS of TTR null mice, we observed a hypermyelination phenotype, synchronous with an increase in the density of oligodendrocytes in the corpus callosum and anterior commissure of TTR null mice during postnatal development. Furthermore, absence of TTR enhanced proliferation and migration of OPCs with decreased apoptosis. Neural stem cells (NSCs) isolated from the subventricular zone of TTR null mice at P21 revealed that the absence of TTR promoted NSC differentiation toward a glial lineage. Importantly, we identified TTR synthesis in OPCs, suggestive of an alternate biological function in these cells that may extend beyond an extracellular TH-distributor protein. The hypermyelination mechanism may involve increased pAKT (involved in oligodendrocyte maturation) in TTR null mice. Elucidating the regulatory role of TTR in NSC and OPC biology could lead to potential therapeutic strategies for the treatment of acquired demyelinating diseases.

Transthyretin expression in the postischemic brain.

The unknown role of the carrier protein transthyretin (TTR) in mechanisms of functional recovery in the postischemic brain prompted us to study its expression following experimental stroke. Male C57/B6 mice (age 9 to 10 weeks) were subjected to permanent focal ischemia induced by photothrombosis (PT) and brain tissues were analyzed for ttr expression and TTR levels at 24 hours, 48 hours, 7 days and 14 days following the insult by RT-PCR, Western blot and immunohistochemistry. Fourteen days after PT, non-specific TTR-like immunoreactive globules were found in the ischemic core and surrounding peri-infarct region by immunohistochemistry that could not be allocated to DAPI positive cells. No TTR immunoreactivity was found when stainings were performed with markers for neurons (Neuronal Nuclei, NeuN), reactive astrocytes (glial fibrillary acidic protein, GFAP) or microglia (cluster of differentiation 68, CD68). In addition, we could not find TTR by immunoblotting in protein extracts obtained from the ischemic territory nor ttr expression by RT-PCR at all time points following PT. In all experiments, ttr expression in the choroid plexus and TTR in the mouse serum served as positive controls and recombinant legumain peptide as negative control. Together, our results indicate that TTR is not synthesized in brain resident cells in the ischemic infarct core and adjacent peri-infarct area. Thus, it seems unlikely that in situ synthesized TTR is involved in mechanisms of tissue reorganization during the first 14 days following PT.

Single-centre experience on transthyretin familial amyloid polyneuropathy: case series and literature review.

Familial amyloid polyneuropathy (FAP) is a most often length-dependent axonal neuropathy, often part of a multisystem disorder also affecting other organs, such as cardiac, gastrointestinal, genitourinary, renal, meningeal and eye tissue. It is most frequently the result of a mutation in the TTR gene, most commonly a p.Val50Met mutation. TTR-FAP is a rare autosomal dominant heritable disabling, heterogeneous disease in which early diagnosis is of pivotal importance when attempting treatment. This paper discusses the course of four Belgian FAP patients with different TTR mutations (p.Val48Met; p.Val52Ala; p.Ala59Val; p.Val50Met). We also review the diagnosis and differential diagnosis of TTR-FAP, diagnostic studies, follow-up, its current treatment and those in development, prognosis and the importance of genetic counseling. At first, TTR-FAP is often misdiagnosed as a chronic inflammatory demyelinating polyneuropathy or chronic idiopathic axonal polyneuropathy. Genetic testing is obligatory to confirm the diagnosis of TTR-FAP, except in familial cases. Biopsy samples are an asset in diagnosing TTR-FAP but can be falsely negative. At the moment, tafamidis meglumine is considered as first-line treatment in stage I neurological disease. Patients eligible for liver transplantation should be carefully selected when first-line therapy fails.

Directional thyroid hormone distribution via the blood stream to target sites.

Thyroid hormones are bound to three major serum transport proteins, thyroxin-binding globulin (TBG), transthyretin (TTR) and human serum albumin (HSA). TBG has the strongest affinity for thyroid hormones, TTR is also found in the cerebrospinal fluid and HSA is the most abundant protein in plasma. Combination defects of either a high affinity TTR or HSA variant do not compensate TBG deficiency, underscoring the dominant role of TBG among the thyroid hormone transport proteins. On the other hand, coexistence of raised affinity TTR and HSA variants causes an augmented hyperthyroxinemia. Variations in thyroid hormone transport proteins may alter thyroid function tests to mimic hypo- or hyperthyroidism. As affected individuals are clinically euthyroid and do not require treatment, identification of thyroid hormone transport protein defects is important to avoid unnecessary diagnostic and therapeutic interventions. Mammals share the multilayered system of thyroid hormone binding proteins with humans. Some of them, especially carnivores, do not express TBG. In dogs, this defect has been shown to be caused by a defective hepatocyte nuclear factor-1 binding site in the TBG promoter, preventing TBG synthesis in the liver. The major endogenous thyroid hormone metabolite 3-iodothyronamine (3-T1AM) exerts marked cryogenic, metabolic, cardiac and central nervous system actions. It is bound to apolipoproteinB-100 (ApoB100), possibly facilitating its cellular uptake via interaction with the low density lipoprotein-receptor. This review summarizes the handling of hydrophobic charged thyroid hormone signaling molecules and their metabolite 3-T1AM in aqueous body fluids and the advantages and limits of their serum distributor proteins.

Label-free quantitative comparison of cerebrospinal fluid glycoproteins and endogenous peptides in subjects with Alzheimer's disease, mild cognitive impairment, and healthy individuals.

PURPOSE: The goal of this study is to investigate putative molecular dynamic changes in cerebrospinal fluids (CSFs) collected from individuals with mild cognitive impairment (MCI) and Alzheimer's disease (AD) as compared to healthy controls. EXPERIMENTAL DESIGN: The CSF samples from 12 subjects comprised of four cognitively normal individuals and eight patients with MCI and AD, respectively. Two aliquots of each CSF samples (total 1 mL) of each participant are used for this study. Endogenous peptide separations are performed using 10 000 molecular weight cut-off filters followed by LC-MS/MS identification and quantitation while lectin-enrichment chromatography is used to enrich glycoproteins in CSF followed by trypsin digestion and subsequent LC-MS/MS for shotgun identification and label-free quantitation. RESULTS: Using an optimized submicrogram peptide separation with molecular weight cut-off filtration and an in house-constructed database, 645 peptides are identified. Glycoproteins are enriched by lectin affinity chromatography, resulting in 795 identified proteins. The discovery and alterations of proSAAS-derived peptides and transthyretin are described and their roles in AD are discussed. CONCLUSIONS AND CLINICAL RELEVANCE: Comprehensive identification of endogenous CSF peptidome is achieved. Fifteen proteins are found to be differentially expressed among the three groups. The dynamic changes of transthyretin are reported for the first time.

CNS involvement in V30M transthyretin amyloidosis: clinical, neuropathological and biochemical findings.

OBJECTIVES: Since liver transplant (LT) was introduced to treat patients with familial amyloid polyneuropathy carrying the V30M mutation (ATTR-V30M), ocular and cardiac complications have developed. Long-term central nervous system (CNS) involvement was not investigated. Our goals were to: (1) identify and characterise focal neurological episodes (FNEs) due to CNS dysfunction in ATTR-V30M patients; (2) characterise neuropathological features and temporal profile of CNS transthyretin amyloidosis. METHODS: We monitored the presence and type of FNEs in 87 consecutive ATTR-V30M and 35 non-ATTR LT patients. FNEs were investigated with CT scan, EEG and extensive neurovascular workup. MRI studies were not performed because all patients had cardiac pacemakers as part of the LT protocol. We characterised transthyretin amyloid deposition in the brains of seven ATTR-V30M patients, dead 3-13 years after polyneuropathy onset. RESULTS: FNEs occurred in 31% (27/87) of ATTR-V30M and in 5.7% (2/35) of the non-ATTR transplanted patients (OR=7.0, 95% CI 1.5 to 33.5). FNEs occurred on average 14.6 years after disease onset (95% CI 13.3 to 16.0) in ATTR-V30M patients, which is beyond the life expectancy of non-transplanted ATTR-V30M patients (10.9, 95% CI 10.5 to 11.3). ATTR-V30M patients with FNEs had longer disease duration (OR=1.24; 95% CI 1.07 to 1.43), renal dysfunction (OR=4.65; 95% CI 1.20 to 18.05) and were men (OR=3.57; 95% CI 1.02 to 12.30). CNS transthyretin amyloidosis was already present 3 years after polyneuropathy onset and progressed from the meninges and its vessels towards meningocortical vessels and the superficial brain parenchyma, as disease duration increased. CONCLUSIONS: Our findings indicate that CNS clinical involvement occurs in ATTR-V30M patients regardless of LT. Longer disease duration after LT can provide the necessary time for transthyretin amyloidosis to progress until it becomes clinically relevant. Highly sensitive imaging methods are needed to identify and monitor brain ATTR. Disease modifying therapies should consider brain TTR as a target.

Assessing experimental visceral pain in dairy cattle: A pilot, prospective, blinded, randomized, and controlled study focusing on spinal pain proteomics.

Few studies have verified the validity of behavioral and physiological methods of pain assessment in cattle. This prospective, blinded, randomized controlled experimental study aimed to validate different methods of pain assessment during acute and chronic (up to 21 d postintervention) conditions in dairy cattle, in response to 3 analgesic treatments for traumatic reticuloperitonitis. Cerebrospinal fluid (CSF) biomarkers and mechanical sensitization were measured as indicators of centralized pain. Proteomics in the CSF were examined to detect specific (to pain intensity) and sensitive (responsive to analgesia) markers. Recordings of spontaneous behavior with video analysis, telemetered motor activity, pain scales, electrodermal activity, and plasma cortisol concentration were quantified at regular intervals. Cows were assigned to group 1 (n=4, standard control receiving aspirin), group 2 (n=5, test group receiving preemptive tolfenamic acid), or group 3 (n=3, positive control receiving preemptive multimodal analgesia composed of epidural morphine, plus tolfenamic acid and butorphanol). Rescue analgesia was administered as needed. Generalized estimating equations tested group differences and the influence of rescue analgesia on the measurements. All 3 groups demonstrated a long-term decrease in a CSF protein identified as transthyretin. The decrease in transthyretin expression inversely correlated with the expected level of analgesia (group 1<2<3). Moreover, in group 1, CSF noradrenaline decreased long term, cows were hypersensitive to mechanical stimulation, and they demonstrated signs of discomfort with higher motor activity and "agitation while lying" recorded from video analysis. Decreased "feeding behavior," observer-reported pain scales, electrodermal activity, and plasma cortisol concentration were inconsistent to differentiate pain intensity between groups. In summary, changes in CSF biomarkers and mechanical sensitization reflected modulation of central pain in dairy cows. The spontaneous behavior "agitation while lying" was the only behavioral outcome validated for assessing acute and chronic pain in this visceral pain model.

Role of the subcommissural organ in the pathogenesis of congenital hydrocephalus in the HTx rat.

The present investigation was designed to clarify the role of the subcommissural organ (SCO) in the pathogenesis of hydrocephalus occurring in the HTx rat. The brains of non-affected and hydrocephalic HTx rats from embryonic day 15 (E15) to postnatal day 10 (PN10) were processed for electron microscopy, lectin binding and immunocytochemistry by using a series of antibodies. Cerebrospinal fluid (CSF) samples of non-affected and hydrocephalic HTx rats were collected at PN1, PN7 and PN30 and analysed by one- and two-dimensional electrophoresis, immunoblotting and nanoLC-ESI-MS/MS. A distinct malformation of the SCO is present as early as E15. Since stenosis of the Sylvius aqueduct (SA) occurs at E18 and dilation of the lateral ventricles starts at E19, the malformation of the SCO clearly precedes the onset of hydrocephalus. In the affected rats, the cephalic and caudal thirds of the SCO showed high secretory activity with all methods used, whereas the middle third showed no signs of secretion. At E18, the middle non-secretory third of the SCO progressively fused with the ventral wall of SA, resulting in marked aqueduct stenosis and severe hydrocephalus. The abnormal development of the SCO resulted in the permanent absence of Reissner's fibre (RF) and led to changes in the protein composition of the CSF. Since the SCO is the source of a large mass of sialilated glycoproteins that form the RF and of those that remain CSF-soluble, we hypothesize that the absence of this large mass of negatively charged molecules from the SA domain results in SA stenosis and impairs the bulk flow of CSF through the aqueduct.

Effects on transthyretin in plasma and cerebrospinal fluid by DHA-rich n - 3 fatty acid supplementation in patients with Alzheimer's disease: the OmegAD study.

Transthyretin (TTR) binds amyloid-ß (Aß) and may reduce brain Aß, a pathological feature in Alzheimer's disease (AD). N - 3 fatty acids (FA), docosahexaenoic (DHA), and eicosapentaenoic acid (EPA) may increase TTR transcription in rat hippocampus. We studied effects of n - 3 FA supplementation on TTR-levels in patients with AD. Outpatients were randomized to receive 1.7 g DHA and 0.6 g EPA (n - 3/n - 3 group) or placebo (placebo/n - 3 group) during 6 months. After 6 months, all patients received n - 3 FA for another 6 months. TTR and FA were measured in plasma in all subjects, whereas TTR in cerebrospinal fluid (CSF) was measured in a subgroup. The study was completed by 89 patients in the n - 3/n - 3 group (75 y, 57% w) and 85 in the placebo/n - 3 group (75 y, 46% w). Baseline plasma-TTR was within normal range in both groups. After 6 months, plasma-TTR decreased in the placebo/n - 3 group (p < 0.001 within and p < 0.015 between the groups). No changes were observed in CSF TTR. From 6 to 12 months when both groups were supplemented, plasma-TTR increased significantly in both groups. Repeated measures ANOVA indicated an increase in TTR over time (p = 0.04) in those receiving n - 3 FA for 12 months. By linear regression analyses, n - 3 FA treatment was independently associated with increased plasma-TTR at 6 months (ß = -0.172, p = 0.028). Thus, n - 3 FA treatment appeared to increase plasma-TTR in patients with AD. Since TTR may influence Aß deposition in the brain, the results warrant further exploration.

Presence of N-glycosylated transthyretin in plasma of V30M carriers in familial amyloidotic polyneuropathy: an escape from ERAD.

Familial amyloid polyneuropathy (FAP) is an autosomal dominant disease characterized by deposition of amyloid related to the presence of mutations in the transthyretin (TTR) gene. TTR is mainly synthesized in liver, choroid plexuses of brain and pancreas and secreted to plasma and cerebrospinal fluid (CSF). Although it possesses a sequon for N-glycosylation N-D-S at position 98, it is not secreted as a glycoprotein. The most common FAP-associated mutation is TTR V30M. In a screening for monoclonal antibodies developed against an amyloidogenic TTR form, we detected a distinct TTR with slower electrophoretic mobility in Western of plasma from carriers of the V30M mutation, not present in normal plasma. Mass spectrometry analyses of this slower migrating TTR (SMT) identified both wild-type and mutant V30M; SMT was undetectable upon N-glycosidase F treatment. Furthermore, SMT readily disappeared in the plasma of V30M - FAP patients after liver transplantation and appeared in plasma of transplanted domino individuals that received a V30M liver. SMT was also detected in plasma, but not in CSF of transgenic mice for the human V30M mutation. A hepatoma cell line transduced to express human V30M did not present the SMT modification in secretion media. Glycosylated TTR was absent in fibrils extracted from human kidney V30M autopsy tissue or in TTR aggregates extracted from the intestine of human TTR transgenic mice. Studies on the metabolism of this novel, glycosylated TTR secreted from FAP liver are warranted to provide new mechanisms in protein quality control and etiopathogenesis of the disease.

Oxidative modifications of cerebral transthyretin are associated with multiple sclerosis.

Transthyretin (TTR) is a homotetrameric protein of the CNS that plays a role of as the major thyroxine (T4) carrier from blood to cerebrospinal fluid (CSF). T4 physiologically helps oligodendrocyte precursor cells to turn into myelinating oligodendrocytes, enhancing remyelination after myelin sheet damage. We investigated post-translational oxidative modifications of serum and CSF TTR in multiple sclerosis subjects, highlighting high levels of S-sulfhydration and S-sulfonation of cysteine in position ten only in the cerebral TTR, which correlate with an anomalous TTR protein folding as well as with disease duration. Moreover, we found low levels of free T4 in CSF of multiple sclerosis patients, suggestive of a potential role of these modifications in T4 transport into the brain.

Serum and cerebrospinal fluid levels of transthyretin in Lewy body disorders with and without dementia.

Parkinson's disease (PD) without (non-demented, PDND) and with dementia (PDD), and dementia with Lewy bodies (DLB) are subsumed under the umbrella term Lewy body disorders (LBD). The main component of the underlying pathologic substrate, i.e. Lewy bodies and Lewy neurites, is misfolded alpha-synuclein (Asyn), and--in particular in demented LBD patients--co-occurring misfolded amyloid-beta (Abeta). Lowered blood and cerebrospinal fluid (CSF) levels of transthyretin (TTR)--a clearance protein mainly produced in the liver and, autonomously, in the choroid plexus--are associated with Abeta accumulation in Alzheimer's disease. In addition, a recent study suggests that TTR is involved in Asyn clearance. We measured TTR protein levels in serum and cerebrospinal fluid of 131 LBD patients (77 PDND, 26 PDD, and 28 DLB) and 72 controls, and compared TTR levels with demographic and clinical data as well as neurodegenerative markers in the CSF. Five single nucleotide polymorphisms of the TTR gene which are considered to influence the ability of the protein to carry its ligands were also analyzed. CSF TTR levels were significantly higher in LBD patients compared to controls. Post-hoc analysis demonstrated that this effect was driven by PDND patients. In addition, CSF TTR levels correlated negatively with CSF Abeta(1-42), total tau and phospho-tau levels. Serum TTR levels did not significantly differ among the studied groups. There were no relevant associations between TTR levels and genetic, demographic and clinical data, respectively. These results suggest an involvement of the clearance protein TTR in LBD pathophysiology, and should motivate to elucidate TTR-related mechanisms in LBD in more detail.

Cerebrospinal fluid biomarkers of neuropathologically diagnosed Parkinson's disease subjects.

OBJECTIVES: Parkinson's disease (PD) afflicts approximately 1-2% of the population over 50 years of age. No cures or effective modifying treatments exist and clinical diagnosis is currently confounded by a lack of definitive biomarkers. We sought to discover potential biomarkers in the cerebrospinal fluid (CSF) of neuropathologically confirmed PD cases. METHODS: We compared postmortem ventricular CSF (V-CSF) from PD and normal control (NC) subjects using two-dimensional difference gel electrophoresis (2D-DIGE). Spots exhibiting a 1·5-fold or greater difference in volume between PD patients and controls were excised from the two-dimensional gels, subjected to tryptic digestion and identification of peptides assigned using mass spectrometric/data bank correlation methods. RESULTS: Employing this strategy six molecules: fibrinogen, transthyretin, apolipoprotein E, clusterin, apolipoprotein A-1, and glutathione-S-transferase-Pi, were found to be different between PD and NC populations. DISCUSSION: These molecules have been implicated in PD pathogenesis. Combining biomarker data from multiple laboratories may create a consensus panel of proteins that may serve as a diagnostic tool for this neurodegenerative disorder.

Characterization and stability of transthyretin isoforms in cerebrospinal fluid examined by immunoprecipitation and high-resolution mass spectrometry of intact protein.

Post-translational modifications (PTMs) contribute significantly to the complexity of proteins. PTMs may vary in certain patterns according to diseases and microenviroments making them potential markers for pathological processes. Human transthyretin (TTR) is a transporter of thyroxine and retinol in blood and cerebrospinal fluid (CSF). A single free cysteine thiol group in TTR possesses the ability to form mixed disulfides potentially related to diseases such as TTR amyloidosis and Alzheimer's disease (AD). Additionally, TTR-Cys10 S-thiolations might mirror the oxidative stress and redox balance of CSF. Here we describe a quick and gentle method for immunoprecipitating (IP) TTR from CSF with minimal introduction of sample-handling artifacts. A high-resolution mass spectrometer (LTQ-Orbitrap XL) was used in a simple setup with direct infusion that generates data suitable for confident assignment of TTR isoforms and validation of the protocol. Moreover, we demonstrate how simple storage of CSF at 4°C induces major oxidative modifications of TTR. Using the optimized method, we show data from a limited number of mild cognitive impairment (MCI) and AD patients. The protocol controls and minimizes the introduction of sample-handling artifacts during purification of TTR isoforms for high-resolution MS analysis.

Genetic analysis of genes involved in amyloid-ß degradation and clearance in Alzheimer's disease.

Accumulation of amyloid ß-peptide (Aß) in the brain of Alzheimer's disease (AD) patients has been postulated to reflect defects in Aß degradation or clearance. Here, we selected 12 genes (MMEL1, ECE1, ECE2, AGER, PLG, PLAT, NR1H3, MMP3, LRP1, TTR, NR1H2, and MMP9) involved in Aß catabolism on the basis of PubMed-based literature search and elucidated their genetic role in AD among Finnish case-control cohort consisting of total ∼1,300 AD patients and control subjects. Thirty one single nucleotide polymorphisms (SNPs) were selected for genotyping. In a smaller subset of AD patients, cerebrospinal fluid (CSF) levels of Aß42 (n = 124), total-tau (n = 59), and phospho-tau (n = 54) analyses were performed with respect to SNPs. Moreover, age of onset analyses with respect to the studied SNPs were conducted among the AD patient cohort (n = 642). Association analysis of the liver X receptor α (NR1H3) gene SNPs showed a protective effect for C allele carriers of rs7120118 (OR = 0.70, 95% CI 0.53-0.93), while the total-tau and phospho-tau levels in CSF were decreased in AD patients carrying the C allele. Also, a decrease in the age of onset was observed in AD patients carrying the A allele of rs723744 and the C allele of rs3794884 in transthyretin (TTR) gene. However, after adjusting the p-values for multiple comparisons, these results were not statistically significant, suggesting that genetic variations in MMEL1, ECE1, ECE2, AGER, PLG, PLAT, NR1H3, MMP3, LRP1, TTR, NR1H2, and MMP9 genes do not play major role among the Finnish AD patient cohort.

Altered cerebrospinal fluid index of prealbumin, fibrinogen, and haptoglobin in patients with Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy.

OBJECTIVES: Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP) are autoimmune diseases of the peripheral nervous system. A clinical hallmark of GBS and CIDP is the albumino-cytologic dissociation in the cerebrospinal fluid (CSF). Changes in the CSF levels of proteins other than albumin in patients with GBS and CIDP are not as well studied. If altered, aberrant levels of CSF proteins may render it possible to establish useful biomarkers for GBS and CIDP. MATERIALS AND METHODS: Enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of prealbumin, fibrinogen, haptoglobin, apolipoprotein E, apolipoprotein A4 in both CSF and plasma samples from 19 patients with GBS and eight with CIDP, 24 controls with multiple sclerosis (MS) as well as 20 patients with other non-inflammatory neurological disorders (OND). RESULTS: The levels of prealbumin in both the plasma and the CSF were elevated in patients with GBS and MS compared with the controls. The higher levels of fibrinogen were seen in the CSF of patients with GBS and CIDP, but not in the plasma. The levels of CSF prealbumin and fibrinogen, measured by the CSF index of these proteins, were lower in patients with GBS and that of fibrinogen in patients with CIDP compared with controls with OND. Haptoglobin levels in the CSF rather than in the plasma were higher in patients with GBS and CIDP than in controls. The CSF haptoglobin index was higher in patients with CIDP and MS, but not in those with GBS. No correlation was found between levels of CSF proteins and clinical parameters in patients with GBS and CIDP. CONCLUSIONS: Our data provide preliminary evidence that GBS is associated with low CSF index levels of prealbumin and fibrinogen, but normal levels of haptoglobin, whereas CIDP is associated with normal CSF index levels of prealbumin, low fibrinogen, and high levels of haptoglobin. Further studies are needed to identify the underlying mechanisms behind these CSF protein alterations and to clarify whether prealbumin, fibrinogen, and haptoglobin can serve as useful biomarkers for GBS and CIDP.

CSF transthyretin neuroprotection in a mouse model of brain ischemia.

Brain injury caused by ischemia is a major cause of human mortality and physical/cognitive disability worldwide. Experimentally, brain ischemia can be induced surgically by permanent middle cerebral artery occlusion. Using this model, we studied the influence of transthyretin in ischemic stroke. Transthyretin (TTR) is normally responsible for the transport of thyroid hormones and retinol in the blood and CSF. We found that TTR null mice (TTR(-/-) ) did not show significant differences in cortical infarction 24 h after permanent middle cerebral artery occlusion compared with TTR(+/+) control littermates. However, TTR null mice, heterozygous for the heat-shock transcription factor 1 (TTR(-/-) HSF1(+/-) mice), which compromised the stress response, showed a significant increase in cortical infarction, cerebral edema and the microglial-leukocyte response compared with TTR(+/+) HSF1(+/-) mice. Unexpectedly, we observed novel TTR distribution throughout the infarct, localized to disintegrated ß-tubulin III(+) neurons and cell debris. Specific elimination of TTR synthesis in the liver by RNAi had no effect on TTR distribution in the infarct, indicating that the observed TTR infiltration derived from CSF and not from the serum. This finding is corroborated by results from 'in situ' hybridization and real time PCR that excluded the presence of transthyretin mRNA in the infarct and peri-infarct areas. Our data suggest that in conditions of a compromised heat-shock response, CSF TTR contributes to control neuronal cell death, edema and inflammation, thereby influencing the survival of endangered neurons in cerebral ischemia.