Publications by authors named "Yannick Tholance"

24 Publications

  • Page 1 of 1

CIDP Antibodies Target Junction Proteins and Identify Patient Subgroups: An Autoantigenomic Approach.

Authors:
Christian P Moritz Yannick Tholance Oda Stoevesandt Karine Ferraud Jean-Philippe Camdessanché Jean-Christophe Antoine

Neurol Neuroimmunol Neuroinflamm 2021 03 6;8(2). Epub 2021 Jan 6.

From the Department of Neurology (C.P.M., K.F., J.-P.C., J.-C.A.), and Department of Biochemistry (Y.T.), University Hospital of Saint-Etienne; Synaptopathies and Autoantibodies (C.P.M., Y.T., J.-P.C., J.-C.A.), Institut NeuroMyoGène, INSERM U1217/CNRS UMR 5310, University of Lyon, University Jean-Monnet, Saint-Étienne, France; and Cambridge Protein Arrays Ltd. (O.S.), Babraham Research Campus, United Kingdom.

Objective: To discover systemic characteristics in the repertoires of targeted autoantigens in chronic inflammatory demyelinating polyneuropathy (CIDP), we detected the entire autoantigen repertoire of patients and controls and analyzed them systematically.

Methods: We screened 43 human serum samples, of which 22 were from patients with CIDP, 12 from patients with other neuropathies, and 9 from healthy controls via HuProt Human Proteome microarrays testing about 16,000 distinct human bait proteins. Autoantigen repertoires were analyzed via bioinformatical autoantigenomic approaches: principal component analysis, analysis of the repertoire sizes in disease groups and clinical subgroups, and overrepresentation analyses using Gene Ontology and PantherDB.

Results: The autoantigen repertoires enabled the identification of a subgroup of 10/22 patients with CIDP with a younger age at onset and a higher frequency of mixed motor and sensory CIDP. IV immunoglobulin therapy responders targeted 3 times more autoantigens than nonresponders. No CIDP-specific autoantibody is present in all patients; however, anchoring junction components were significantly targeted by 86.4% of patients with CIDP. There are potential novel CIDP-specific autoantigens such as the myelination- or axo-glial structure-related proteins actin-related protein 2/3 complex subunit 1B, band 4.1-like protein 2, cadherin-15, cytohesin-1, epidermal growth factor receptor, ezrin, and radixin.

Conclusions: The repertoire of targeted autoantigens of patients with CIDP differs in a systematic degree from those of controls. Systematic autoantigenomic approaches can help to understand the disease and to discover novel bioinformatical tools and novel autoantigen panels to improve diagnosis, treatment, prognosis, or patient stratification.
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http://dx.doi.org/10.1212/NXI.0000000000000944DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7862091PMC
March 2021

Proper definition of the set of autoantibody-targeted antigens relies on appropriate reference group selection.

Authors:
Christian P Moritz Oda Stoevesandt Yannick Tholance Jean-Philippe Camdessanché Jean-Christophe Antoine

N Biotechnol 2021 Jan 9;60:168-172. Epub 2020 Oct 9.

Synaptopathies and Autoantibodies, Institut NeuroMyoGene INSERM U1217/CNRS UMR, Faculty of Medicine Jacques Lisfranc, University Jean Monnet, University of Lyon, Saint-Étienne, France; Department of Neurology, Centre Hospitalier Universitaire de Saint-Étienne, Saint-Étienne, France.

Autoimmune diseases are frequently associated with autoantibodies. Recently, large sets of autoantibody-targeted antigens ("autoantigen-omes") of patient and control sera have been revealed, enabling autoantigen-omic approaches. However, statistical standards for defining such autoantigen-omes are lacking. The z-score indicates how many standard deviations an antigen reactivity of a given sample is from the mean reactivity of the corresponding antigen in a reference group. Hence, it is a common measure to define significantly positive reactivity in autoantigen profiling approaches. Here, we address the risk of biased analyses resulting from unbalanced selection of the reference group. Three study groups were selected. Patients-of-interest were chronic inflammatory demyelinating polyneuropathy (CIDP); controls were other neuropathies (ONP); and healthy controls (HC). Each serum was screened for significant autoantigen reactivity using HuProt™ protein arrays. We compared three possible selections of reference groups for statistical z-score calculations: method#1, the control groups (ONP + HC); method #2, all groups together; method #3, the respective other groups (e.g., CIDP + HC for the ONP autoantigen-ome). The method selection seriously affected the size of the autoantigen-omes. Method #1 introduced a bias favoring significantly more antigens per patient in the CIDP group (for z >4: 19 ± 3 antigens) than in the control groups (ONP: 2 ± 1; HC: 0 ± 0). The more balanced methods #2 and #3 did not result in significant differences. This contribution may help to avoid interpretation biases and to develop guidelines for population studies revealing autoantigen-omes via high throughput studies such as protein microarrays, immunoprecipitation with mass spectrometry, or phage display assays.
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http://dx.doi.org/10.1016/j.nbt.2020.08.007DOI Listing
January 2021

COVID-19 and Guillain-Barré syndrome: Response.

Authors:
Jean-Philippe Camdessanché Jérôme Morel Bruno Pozzetto Stéphane Paul Yannick Tholance Elisabeth Botelho-Nevers

Rev Neurol (Paris) 2020 09 15;176(7):636-637. Epub 2020 May 15.

University Hospital of Saint-Etienne, 42055 Saint-Etienne cedex 02, France.

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http://dx.doi.org/10.1016/j.neurol.2020.05.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7225720PMC
September 2020

Delaying Centrifugation and Freezing by Adding a Dihydropyrimidine Dehydrogenase Inhibitor Such as Gimeracil to Blood Sample Is Not a Valid Option to Simplify the Preanalytic Step for the Screening of Dihydropyrimidine Dehydrogenase Deficiency Using Uracilemia.

Authors:
Manon Launay Yara Nasser Yannick Tholance Sandrine Dellinger Philippe Gonzalo Xavier Delavenne

Ther Drug Monit 2020 04;42(2):344-345

Department of Pharmacology, Toxicology and Blood Gases, University Hospital of Saint-Etienne, Saint-Etienne, France.

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http://dx.doi.org/10.1097/FTD.0000000000000716DOI Listing
April 2020

Autoantigenomics: Holistic characterization of autoantigen repertoires for a better understanding of autoimmune diseases.

Authors:
Christian P Moritz Stéphane Paul Oda Stoevesandt Yannick Tholance Jean-Philippe Camdessanché Jean-Christophe Antoine

Autoimmun Rev 2020 Feb 12;19(2):102450. Epub 2019 Dec 12.

Synaptopathies and Autoantibodies, Institut NeuroMyoGene INSERM U1217/CNRS UMR, Faculty of Medicine Jacques Lisfranc, University Jean Monnet, University of Lyon, Saint-Étienne, France; Department of Neurology, Centre Hospitalier Universitaire de Saint-Étienne, Saint-Étienne, France.

Autoimmune diseases are mostly characterized by autoantibodies in the patients' serum or cerebrospinal fluid, representing diagnostic or prognostic biomarkers. For decades, research has focused on single autoantigens or panels of single autoantigens. In this article, we advocate to broaden the focus by addressing the entire autoantigen repertoire in a systemic "omics-like" way. This approach aims to capture the enormous biodiversity in the sets of targeted antigens and pave the way toward a more holistic understanding of the concerted character of antibody-related humoral immune responses. Ongoing technological progress permits high-throughput screenings of thousands of autoantigens in parallel, e.g., via protein microarrays, phage display, or immunoprecipitation with mass spectrometry. We argue that the time is right for combining omics and autoantibody screening approaches into "autoantigenomics" as a novel omics subcategory. In this article, we introduce the concept of autoantigenomics, describe its roots and application options, and demarcate the method from related holistic approaches such as systems serology or immune-related transcriptomics and proteomics. We suggest the following extendable method set to be applied to autoantigen repertoires: (1) principal component analysis, (2) hierarchical cluster analysis, (3) partial least-square discriminant analysis or orthogonal projections to latent structures discriminant analysis, (4) analysis of the repertoire sizes in disease groups and clinical subgroups, (5) overrepresentation analyses using databases like those of Gene Ontology, Reactome Pathway, or DisGeNET, (6) analysis of pathways that are significantly targeted by specific repertoires, and (7) machine learning approaches. In an unsupervised way, these methods can identify clusters of autoantigens sharing certain functional or spatial properties, or clusters of patients comprising clinical subgroups potentially useful for patient stratification. In a supervised way, these methods can lead to prediction models that may eventually assist diagnosis and prognosis. The untargeted autoantigenomics approach allows for the systematic survey of antibody-related humoral immune responses. This may enhance our understanding of autoimmune diseases in a more comprehensive way compared to current single or panel autoantibodies approaches.
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http://dx.doi.org/10.1016/j.autrev.2019.102450DOI Listing
February 2020

Clinical characterisation of sensory neuropathy with anti-FGFR3 autoantibodies.

Authors:
Yannick Tholance Christian Peter Moritz Carole Rosier Karine Ferraud François Lassablière Evelyne Reynaud-Federspiel Marcondes C França Alberto R M Martinez Jean-Philippe Camdessanché Jean-Christophe Antoine

J Neurol Neurosurg Psychiatry 2020 01 5;91(1):49-57. Epub 2019 Nov 5.

Synaptopathies et autoanticorps (synatac), Institut Neuromyogène, Saint-Priest-en-Jarez, France.

Objective: Sensory neuropathies (SNs) are often classified as idiopathic even if immunological mechanisms can be suspected. Antibodies against the intracellular domain of the fibroblast growth factor receptor 3 (FGFR3) possibly identify a subgroup of SN affecting mostly the dorsal root ganglion (DRG). The aim of this study was to identify the frequency of anti-FGFR3 antibodies and the associated clinical pattern in a large cohort of patients with SN.

Methods: A prospective, multicentric, European and Brazilian study included adults with pure SN. Serum anti-FGRF3 antibodies were analysed by ELISA. Detailed clinical and paraclinical data were collected for each anti-FGFR3-positive patient and as control for anti-FGFR3-negative patients from the same centres ('center-matched').

Results: Sixty-five patients out of 426 (15%) had anti-FGFR3 antibodies, which were the only identified autoimmune markers in 43 patients (66%). The neuropathy was non-length dependent in 89% and classified as sensory neuronopathy in 64%, non-length-dependent small fibre neuropathy in 17% and other neuropathy in 19%. Specific clinical features occurred after 5-6 years of evolution including frequent paresthesia, predominant clinical and electrophysiological involvement of the lower limbs, and a less frequent mixed large and small fibre involvement. Brazilians had a higher frequency of anti-FGFR3 antibodies than Europeans (36% vs 13%, p<0.001), and a more frequent asymmetrical distribution of symptoms (OR 169, 95% CI 3.4 to 8424).

Conclusions: Anti-FGFR3 antibodies occur in a subgroup of SN probably predominantly affecting the DRG. Differences between Europeans and Brazilians could suggest involvement of genetic or environmental factors.
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http://dx.doi.org/10.1136/jnnp-2019-321849DOI Listing
January 2020

Metabolic alterations of uterine grafts after extended cold ischemic storage: experimental study in ewes.

Authors:
Yannick Tholance Jeremy Tricard Thierry Chianea Pierre Marquet Sébastien Ponsonnard Franck Sturtz Alessandro Piccardo Tristan Gauthier

Mol Hum Reprod 2019 10;25(10):647-659

Individual Profiling and Prevention of Risks with Immunosuppressive Therapies and Transplantation, UMR 1248 INSERM, School of Medicine, University of Limoges, F-87000 Limoges, France.

Uterine transplantation from a deceased donor could become an available option for widely treating uterine infertility. However, this procedure requires more precise knowledge about the graft's tolerance to extended cold ischemia. Here, we sought to assess the uterine metabolic alterations after extended cold ischemic storage in a model of auto-transplantation in ewe. A total of 14 uterine auto-transplantations were performed, divided into 2 groups: 7 after 3 h of cold ischemia time (CIT) and 7 after 24 h. Venous uterine blood was collected before uterus retrieval and during reperfusion (30, 60 and 90 min); thereafter, blood gases, lactate, glucose and amino acids (AAs) were analyzed. Apoptosis analyses were performed before uterus retrieval and following reperfusion in uterus biopsies. A total of 12 uterine auto-transplantations were successfully performed and 7 ewes were alive ≥8 days after transplantation. After reperfusion, a decrease in pH, a rise of lactate and lactate/glucose ratio and a delayed decrease of pO2 were found in the 3 h CIT group. No significant variation of these parameters was observed in the 24 h CIT group. Significant decreases of AAs were observed during reperfusion and these decreases were more pronounced and concerned a larger number of compounds in the 24 h CIT group than in the 3 h CIT group. There was no significant uterine apoptotic signal in either group. Overall, these results suggest that extended CIT storage delayed restoration of aerobic glycolysis and induced an increase in AA requirements of the uterus after reperfusion. However, this biochemical alteration did not reduce success rate for uterine transplantation.
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http://dx.doi.org/10.1093/molehr/gaz041DOI Listing
October 2019

Completing the Immunological Fingerprint by Refractory Proteins: Autoantibody Screening via an Improved Immunoblotting Technique.

Authors:
Christian P Moritz Yannick Tholance Carole Rosier Evelyne Reynaud-Federspiel Juliette Svahn Jean-Philippe Camdessanché Jean-Christophe Antoine

Proteomics Clin Appl 2019 07 4;13(4):e1800157. Epub 2019 Mar 4.

Synaptopathies and Autoantibodies, Faculty of Medicine Jacques Lisfranc, University Jean Monnet, University of Lyon, 42270, Saint-Priest en Jarez, France.

Purpose: Identifying autoantigens of serological autoantibodies requires expensive methods, such as protein microarrays or IP+MS. Thus, sera are commonly pre-screened for interesting immunopatterns via immunocytochemistry/immunohistochemistry. However, distinguishing immunopatterns can be difficult and intracellular antigens are less accessible. Therefore, a simple and cheap immunoblot screening able to distinguish immunopatterns and to detect refractory proteins is presented.

Experimental Design: Five steps of immunoblotting-based autoantigen screening are revised: (1) choice of protein source, (2) protein extraction, (3) protein separation, (4) protein transfer, (5) antigen detection. Thereafter, 52 patients' sera with chronic inflammatory demyelinating polyneuropathy (CIDP) and 45 controls were screened.

Results: The protein source impacts the detected antigen set. Steps 2-4 can be adapted for refractory proteins. Furthermore, longitudinal cutting of protein lanes saves ≥75% of time and material and allows for exact comparison of band patterns. As the latter are individually specific and temporarily constant, we call them "immunological fingerprints". In a proof-of-principle, a 155 kDa immunoband was detected with two anti-neurofascin-155-positive CIDP sera and two further immunobands (120/220 kDa) specific to a subgroup of 3-6 of 52 CIDP patients.

Conclusions And Clinical Relevance: Adapted immunoblotting is a cheap and simple method for accurate serum screening including refractory and intracellular antigens.
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http://dx.doi.org/10.1002/prca.201800157DOI Listing
July 2019

Reducing the risk of misdiagnosis of indirect ELISA by normalizing serum-specific background noise: The example of detecting anti-FGFR3 autoantibodies.

Authors:
Christian P Moritz Yannick Tholance François Lassablière Jean-Philippe Camdessanché Jean-Christophe Antoine

J Immunol Methods 2019 03 14;466:52-56. Epub 2019 Jan 14.

Synaptopathies and Autoantibodies, Faculty of Medicine Jacques Lisfranc, University Jean Monnet, University of Lyon, Saint-Étienne, France; Synaptopathies and Autoantibodies, Institut NeuroMyoGene INSERM U1217/CNRS UMR 5310, University of Lyon, Université Claude Bernard Lyon 1, Lyon, France; Neurology Department, Centre Hospitalier Universitaire de Saint-Étienne, Saint-Étienne, France.

Indirect enzyme-linked immunosorbent assay (ELISA) is an important diagnostic method as it enables the quantification of the presence of autoantibodies in human blood sera. However, unspecific binding of antibodies to the solid phase causes considerable serum-specific background noise (SSBN), involving the risk of false positive diagnosis. Therefore, we present a simple and concise, yet obvious proof-of-principle of a recently suggested normalization method. The method is based on subtracting SSBN by using non-coated ELISA wells as a control for each serum-of-interest. We performed ELISA to quantify anti-fibroblast growth factor receptor 3 (FGFR3) antibody levels in three positive controls (two anti-FGFR3-positive patients and a rabbit antiserum against FGFR3) and 58 negative controls (healthy blood donors). In all subjects, we found considerable unspecific reactivity which strongly varied among subjects. The conventional normalization method was not able to balance this strong SSBN, as demonstrated by 2/58 false positive healthy controls and one FGFR3-positive patient that was hidden in the noise (false negative). SSBN normalization reduced the frequency of false-positives to 0/58. Further, all three anti-FGFR3-positive sera were successfully detected and even doubled their z-score used to determine positivity. Albeit occupying more space on the ELISA plate, we strongly recommend considering this normalization method when working with blood sera. To better put the idea across to the community, we depict the SSBN issue and its solution in a graphic scheme. We conclude that SSBN normalization increases the sensitivity and specificity of indirect ELISA and thereby reduces the risk of false positive and false negative diagnosis. © 2019. Licensed under the Creative Commons [CC BY-NC 4.0 licence, https://doi.org/10.1016/j.jim.2019.01.004].
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http://dx.doi.org/10.1016/j.jim.2019.01.004DOI Listing
March 2019

Uterus tolerance to extended cold ischemic storage after auto-transplantation in ewes.

Authors:
Jérémy Tricard Sébastien Ponsonnard Yannick Tholance Laura Mesturoux Denis Lachatre Claude Couquet Faraj Terro Catherine Yardin Pierre Marquet Alessandro Piccardo Tristan Gauthier

Eur J Obstet Gynecol Reprod Biol 2017 Jul 16;214:162-167. Epub 2017 May 16.

Department of Pharmacology, Toxicology and Pharmacovigilance, INSERM UMR S-850, Limoges, France; Department of Obstetric and Gynecology, Limoges University Hospital Center, 87000 Limoges, France. Electronic address:

Objective: To assess how the uterus tolerates extended cold ischemic storage before auto-transplantation in ewes.

Study Design: Fourteen uterine auto-transplantations were performed in ewes from November 2014 to June 2015 at the Analysis and Research Laboratory of Limoges, France. The animals were divided into 2 groups: 7 after 3h of cold ischemia timeand 7 after 24h. Transplant was assessed ≥8days after transplantation. Histology and apoptosis analyses (TUNEL method and indirect immunohistochemistry of cleaved Caspase 3) were performed before uterus retrieval (control), after 90min following reperfusion and ≥8days after transplantation.

Results: Twelve uterine auto-transplantations were successfully performed. The histological analysis at 90min following reperfusion revealed a moderate inflammation of the endometrium and serosa in the 3-h group and severe inflammation in the 24-h group, but no significant apoptotic signal was found in either group. Seven ewes were alive at ≥8days after transplantation: the macroscopic and histological analyses revealed two viable uteri in the 3-h group and three in the 24-h group. In each group one uterus was necrotic.

Conclusion: These first results in ewes suggest that the uterus is an organ with a good tolerance to extended cold ischemic storage before transplantation.
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http://dx.doi.org/10.1016/j.ejogrb.2017.05.013DOI Listing
July 2017

Placing intracerebral probes to optimise detection of delayed cerebral ischemia and allow for the prediction of patient outcome in aneurysmal subarachnoid haemorrhage.

Authors:
Yannick Tholance Gleicy K Barcelos Armand Perret-Liaudet Edris Omar Romain Carrillon Sébastien Grousson Thomas Lieutaud Frédéric Dailler Stéphane Marinesco

J Cereb Blood Flow Metab 2017 Aug 1;37(8):2820-2832. Epub 2016 Jan 1.

2 TIGER Team, Lyon Neuroscience Research Center, CNRS, UMR 5292, INSERM U1028, University Lyon 1, Lyon, France.

Cerebral microdialysis could be useful to detect delayed cerebral ischemia in aneurysmal subarachnoid haemorrhage patients. The optimal location of the probes, however, remains controversial. Here, we determined the vascular territories with the highest infarct risk in relation to aneurysm location to define probe implantation guidelines. These guidelines were retrospectively validated by studying the likelihood of probe to fall in a secondary infarct area, and by analysing their influence to predict patient outcome. The vascular territories with highest risk of infarction were the anterior cerebral arteries for anterior communicating artery aneurysms and the ipsilateral middle cerebral artery for internal carotid artery, posterior communicating artery and middle cerebral artery aneurysms. When cerebral microdialysis probes had been implanted in these territories, 79% were located within an infarcted area versus 54% when they were implanted in other territories. Delayed cerebral ischemia was detected only when the probe was located within a brain area later affected by secondary infarction, which could justify the use of implantation guidelines. Moreover, individual patient outcomes could be predicted when probes were placed in the brain territories as suggested by this study. Thus, a precise probe placement algorithm can improve delayed cerebral ischemia detection sensitivity and allow for a better prediction concerning patient outcome.
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http://dx.doi.org/10.1177/0271678X16675880DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5536791PMC
August 2017

Cerebrospinal Fluid Aβ40 Improves the Interpretation of Aβ42 Concentration for Diagnosing Alzheimer's Disease.

Authors:
Aline Dorey Armand Perret-Liaudet Yannick Tholance Anthony Fourier Isabelle Quadrio

Front Neurol 2015 27;6:247. Epub 2015 Nov 27.

Neurochemistry Unit, Biochemistry Department, Hospices Civils de Lyon, Groupement Hospitalier Est , Bron , France ; BioRaN Team, Lyon Neuroscience Research Center, CNRS UMR 5292, INSERM U1028, Lyon 1 University , Bron , France.

The combination of decreased amyloid β42 (Aβ42) and increased total tau proteins (T-Tau) and phosphorylated tau (P-Tau) in cerebrospinal fluid (CSF) has recently been considered as a biological diagnostic criterion of Alzheimer's disease (AD). Previous studies showed significant heterogeneity in CSF Aβ42 levels to discriminate AD from non-AD patients. It was also suggested that the CSF amyloid peptide β42/β40 ratio has better diagnostic performance than Aβ42 alone. The objective of the present study was to investigate the potential added value of determining CSF amyloid β40 peptide (Aβ40) for biological diagnosis of AD when CSF Aβ42 levels failed. CSF AD biomarkers were run in 2,171 samples from 1,499 AD and 672 non-AD patients. The following pathologic thresholds were used to define an AD-positive CSF biomarker profile: T-Tau ≥ 400 ng/L, P-Tau181 ≥ 60 ng/L, and Aβ42 ≤ 700 ng/L. CSF Aβ40 was assayed in AD patients with CSF Aβ42 levels above 700 ng/L and non-AD patients with CSF Aβ42 levels below 700 ng/L. CSF Aβ40 levels were higher in AD than non-AD patients. The receiver operator characteristic curves of CSF Aβ40 and the Aβ42/Aβ40 ratio defined AD cut-off values at 12,644 ng/L and 0.06, respectively. In AD patients with non-pathological CSF Aβ42, CSF Aβ40 concentration was able to correct 76.2% of cases when expressed as CSF Aβ42/Aβ40 ratio and 94.7% of cases when used alone. Using CSF Aβ42 and then CSF Aβ40, the percentage of misinterpreted AD patients fell to 1.0%. CSF Aβ40 concentration improved interpretation of Aβ42 level for the diagnosis of AD. CSF Aβ40 alone showed better diagnostic performance than the amyloid peptide Aβ42/Aβ40 ratio. The added value of determining CSF Aβ40 in AD diagnosis now needs confirming in a cohort of definite AD patients and to be completed with novel amyloid cascade biomarkers.
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http://dx.doi.org/10.3389/fneur.2015.00247DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4661235PMC
December 2015

Clinical Neurochemistry of Subarachnoid Hemorrhage: Toward Predicting Individual Outcomes via Biomarkers of Brain Energy Metabolism.

Authors:
Yannick Tholance Gleicy Barcelos Frederic Dailler Armand Perret-Liaudet Bernard Renaud

ACS Chem Neurosci 2015 Dec 23;6(12):1902-5. Epub 2015 Nov 23.

Neurodialytics Unit, Lyon Neuroscience Research Center, CNRS, UMR 5292, INSERM U1028, Lyon-1 University , 8 Avenue Rockefeller, 69008 Lyon, France.

The functional outcome of patients with subarachnoid hemorrhage is difficult to predict at the individual level. The monitoring of brain energy metabolism has proven to be useful in improving the pathophysiological understanding of subarachnoid hemorrhage. Nonetheless, brain energy monitoring has not yet clearly been included in official guidelines for the management of subarachnoid hemorrhage patients, likely because previous studies compared only biological data between two groups of patients (unfavorable vs favorable outcomes) and did not determine decision thresholds that could be useful in clinical practice. Therefore, this Viewpoint discusses recent findings suggesting that monitoring biomarkers of brain energy metabolism at the level of individuals can be used to predict the outcomes of subarachnoid hemorrhage patients. Indeed, by taking into account specific neurochemical patterns obtained by local or global monitoring of brain energy metabolism, it may become possible to predict routinely, and with sufficient sensitivity and specificity, the individual outcomes of subarachnoid hemorrhage patients. Moreover, combining both local and global monitoring improves the overall performance of individual outcome prediction. Such a combined neurochemical monitoring approach may become, after prospective clinical validation, an important component in the management of subarachnoid hemorrhage patients to adapt individualized therapeutic interventions.
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http://dx.doi.org/10.1021/acschemneuro.5b00299DOI Listing
December 2015

CSF neopterin level as a diagnostic marker in primary central nervous system lymphoma.

Authors:
Aurélien Viaccoz François Ducray Yannick Tholance Gleicy Keli Barcelos Laure Thomas-Maisonneuve Hervé Ghesquières David Meyronet Isabelle Quadrio Stéphanie Cartalat-Carel Guy Louis-Tisserand Emmanuel Jouanneau Jacques Guyotat Jérôme Honnorat Armand Perret-Liaudet

Neuro Oncol 2015 Nov 25;17(11):1497-503. Epub 2015 May 25.

Neuro-oncology Department, Hospices Civils de Lyon, Hôpital Neurologique, Bron, France (A.V., F.D., L.T.-M., S.C.-C., J.H.); INSERM U1028/CNRS UMR 5292, Lyon Neuroscience Research Center, Lyon, France (A.V., F.D., Y.T., G.K.B., L.T.-M., D.M., I.Q., J.H., A.P.-L.); Université de Lyon, Université Claude-Bernard Lyon 1, Lyon, France (A.V., F.D., L.T.-M., J.H.); Neurochemistry Unit, Biochemistry Department, Hospices Civils de Lyon, Hôpital Neurologique, Bron, France (Y.T., I.Q., A.P.-L.); Department of Anesthesiology, Pharmacology and Intensive Care, Geneva University Hospitals, Geneva, Switzerland (G.K.B.); Hematology Department, Centre Léon Bérard, Lyon, France (H.G.); Neuroradiology Department, Hospices Civils de Lyon, Hôpital Neurologique, Bron, France (G.L.-T.); Neurosurgery Department B, Hospices Civils de Lyon, Hôpital Neurologique, Bron, France (E.J.); Neurosurgery Department D, Hospices Civils de Lyon, Hôpital Neurologique, Bron, France (J.G.).

Background: The diagnosis of primary central nervous system lymphoma (PCNSL) can be challenging. PCNSL lesions are frequently located deep within the brain, and performing a cerebral biopsy is not always feasible. The aim of this study was to investigate the diagnostic value of CSF neopterin, a marker of neuroinflammation, in immunocompetent patients with suspected PCNSL.

Methods: We retrospectively reviewed the characteristics of 124 patients with brain tumor (n = 82) or an inflammatory CNS disorder (n = 42) in whom CSF neopterin levels were assessed. Twenty-eight patients had PCNSL, 54 patients had another type of brain tumor (glioma n = 36, metastasis n = 13, other n = 5), and 13 patients had a pseudotumoral inflammatory brain lesion.

Results: CSF neopterin levels were significantly higher in the patients with PCNSL than in those with other brain tumors (41.8 vs 5.1 nmol/L, P < .001), those with pseudotumoral inflammatory brain lesions (41.8 vs 4.3 nmol/L, P < .001), and those with nontumefactive inflammatory CNS disorders (41.8 vs 3.8 nmol/L, P < .001). In the 95 patients with space-occupying brain lesions, at a cutoff of 10 nmol/L, the sensitivity of this approach was 96% and the specificity was 93% for the diagnosis of PCNSL. The positive and negative predictive values were 84% and 98%, respectively.

Conclusion: Assessing CSF neopterin levels in patients with a suspected brain tumor might be helpful for the positive and differential diagnosis of PCNSL. A prospective study is warranted to confirm these results.
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http://dx.doi.org/10.1093/neuonc/nov092DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4648303PMC
November 2015

Biochemical neuromonitoring of poor-grade aneurysmal subarachnoid hemorrhage: comparative analysis of metabolic events detected by cerebral microdialysis and by retrograde jugular vein catheterization.

Authors:
Yannick Tholance Gleicy Keli Barcelos Frédéric Dailler Bernard Renaud Stéphane Marinesco Armand Perret-Liaudet

Neurol Res 2015 Jul 10;37(7):578-87. Epub 2015 Feb 10.

Objectives: In severe aneurysmal subarachnoid hemorrhage (aSAH), pathological changes in cerebral energy metabolism can be detected either by local measurements using cerebral microdialysis (cMD) together with brain tissue oxygen probe or by global measurements of arterio-jugular difference performed with retrograde jugular vein catheter. Our main objective was to compare the two methods of detection and assess whether combining biomarkers from both procedures could improve outcome prediction, which has never been studied before.

Methods: This study included 400 sets of paired arterial and jugular venous samples and 3138 brain microdialyzates obtained from 18 poor-grade aSAH patients. Using Glasgow outcome scale (GOS), neurochemical data from unfavorable (GOS 1-3) and favorable (GOS 4-5) outcome groups were compared.

Results: The lactate/pyruvate ratio was found as the most sensitive marker for predicting unfavorable outcome (90%), although not specific. In contrast, hypoxic lactate events and those of metabolic ratio (MR) < 3.44, most frequently observed in the unfavorable outcome group than in the favorable one (13.9 vs 0.9% and 33.3 vs 3.75% respectively), were shown to be more specific biomarkers (86%) to predict unfavorable outcome, but less sensitive ( < 70%). The combination of these three biomarkers improved the accuracy of outcome prediction (sensitivity 90% and specificity 71%).

Discussion: Both retrograde jugular venous catheterization (RJVC) and cMD contribute to monitor poor-grade aSAH patients. In this preliminary study, we show that these two techniques are complementary and their combination increases the accuracy of outcome prediction.
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http://dx.doi.org/10.1179/1743132815Y.0000000012DOI Listing
July 2015

Association of cerebrospinal fluid prion protein levels and the distinction between Alzheimer disease and Creutzfeldt-Jakob disease.

Authors:
Aline Dorey Yannick Tholance Alain Vighetto Armand Perret-Liaudet Ingolf Lachman Pierre Krolak-Salmon Uta Wagner Hanne Struyfs Peter P De Deyn Benaissa El-Moualij Willy Zorzi David Meyronet Nathalie Streichenberger Sebastiaan Engelborghs Gabor G Kovacs Isabelle Quadrio

JAMA Neurol 2015 Mar;72(3):267-75

Hospices Civils de Lyon, Groupement Hospitalier Est, Department of Biochemistry, Neurochemistry Unit, Lyon, France6Lyon 1 University, Lyon Neuroscience Research Center, Bron Cedex, France.

Importance: Although typical forms of Alzheimer disease (AD) and Creutzfeldt-Jakob disease (CJD) are clinically distinguishable, atypical AD phenotypes may pose a diagnostic challenge. The major biological diagnostic biomarker for identifying CJD, 14-3-3 protein in cerebrospinal fluid (CSF), unfortunately lacks specificity when confronting a rapid dementia presentation.

Objective: To assess the relevance of total CSF prion protein (t-PrP) levels in the differential biological diagnosis between atypical AD phenotypes and CJD.

Design, Setting, And Participants: A retrospective study in an autopsy-confirmed cohort of 82 patients was performed to evaluate the relevance of CSF t-PrP to distinguish 30 definite cases of AD from 52 definite cases of CJD. Next, CSF t-PrP concentration was measured in a cohort of 104 patients including 55 patients with probable AD, 26 with probable sporadic CJD, and 23 control patients for whom 14-3-3 protein, total tau, phosphorylated tau 181 (P-tau181), and Aβ1-42 were available. We investigated 46 patients diagnosed as having probable AD who presented atypical phenotypes. A diagnosis strategy was proposed to classify atypical AD phenotypes with suspicion of CJD based on a decision tree combining CSF biomarkers.

Main Outcomes And Measures: We determined CSF t-PrP levels for all patients. We calculated the ratio of total tau and P-tau181 and determined the diagnostic accuracy of each biomarker alone or in combination. We calculated the misclassification rate for each biomarker that corresponded to the percentage of patients within the group of atypical AD phenotypes wrongly classified as CJD.

Results: In patients with CJD, CSF t-PrP concentrations were decreased compared with control participants and patients with AD. When considering the differential diagnosis of CJD compared with atypical AD phenotypes, CSF t-PrP determination reached 82.1% sensitivity and 91.3% specificity. The misclassification rate of atypical AD phenotypes decreased from 43.5%, obtained when using the CSF 14-3-3 protein determination alone, to only 4.3% when calculating the ratio total tau/(P-tau181 × t-PrP). The proposed classification tree permitted correct classification of 98.4% of the patients.

Conclusions And Relevance: For unusual phenotypes of AD, especially cases presenting with a biological ambiguity suggesting CJD, determination of CSF t-PrP levels increased diagnostic accuracy. The use of CSF t-PrP levels may be beneficial in clinical practice in addition to the current classic biomarkers.
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http://dx.doi.org/10.1001/jamaneurol.2014.4068DOI Listing
March 2015

Outcome of poor-grade subarachnoid hemorrhage as determined by biomarkers of glucose cerebral metabolism.

Authors:
Gleicy K Barcelos Yannick Tholance Sebastien Grousson Bernard Renaud Armand Perret-Liaudet Frederic Dailler Luc Zimmer

Neurocrit Care 2013 Apr;18(2):234-44

BioRaN Team, Lyon Neuroscience Research Center, CNRS UMR 5292, INSERM U1028, University Lyon 1, Lyon, France.

Purpose: The aim of this study was to determine if the measurement of blood biomarkers of glucose cerebral metabolism, performed with retrograde jugular catheter, could predict the outcome of poor-grade aneurysmal subarachnoid hemorrhage (aSAH) patients.

Methods: This study was conducted in 68 poor-grade aSAH patients. A total of 4,024 blood samples obtained from jugular and radial catheters were analyzed for glucose, lactate, and oxygen content every 8 h for 10 ± 0.5 days. Metabolic ratio (MR) and lactate-oxygen index (LOI) were obtained by ratios using arterio-jugular differences. Functional outcome was evaluated at 12 months with the Glasgow Outcome Scale.

Results: Outcome was unfavorable in 40 patients. In this group of patients, the MR was significantly lower (p < 0.0001) and the LOI was significantly higher (p = 0.0001) than in the group with favorable outcome. The MR cutoff value, below which the patients are likely to have an unfavorable outcome, was determined to be 3.35. More interestingly, the data obtained in this study demonstrated that the patients achieving an unfavorable outcome were distinguished from those with a favorable outcome by having at least three events of MR inferior to 3.35 (sensitivity = 90 %, specificity = 82.1 %). Moreover, in patients who developed cerebral vasospasm, we observed a significant decrease in the MR.

Conclusion: Our data provide additional support to the view that the MR is a reliable marker for predicting the outcome of poor-grade aSAH patients. Prospective studies are needed to confirm its value in multimodal monitoring.
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http://dx.doi.org/10.1007/s12028-012-9810-1DOI Listing
April 2013

Risk of Alzheimer's disease biological misdiagnosis linked to cerebrospinal collection tubes.

Authors:
Armand Perret-Liaudet Mathieu Pelpel Yannick Tholance Benoit Dumont Hugo Vanderstichele Willy Zorzi Benaissa Elmoualij Susanna Schraen Olivier Moreaud Audrey Gabelle Eric Thouvenot Catherine Thomas-Anterion Jacques Touchon Pierre Krolak-Salmon Gabor G Kovacs Arnaud Coudreuse Isabelle Quadrio Sylvain Lehmann

J Alzheimers Dis 2012 ;31(1):13-20

Neurobiologie, CMRR, Gériatrie, Hospices Civils de Lyon, Université Lyon 1-CNRS UMR5292-INSERM U1028, Lyon, France.

Tau proteins and amyloid-β (Aβ) peptides are the current recognized cerebrospinal fluid (CSF) biomarkers used as an aid in the diagnosis of Alzheimer's disease (AD). However, there is no consensus on their clinical use due to non-qualified cut-off values, probably related to the observed high pre-analytical and analytical variability. Standardized pre-analytical protocols have therefore been proposed. Importantly, these recommend the use of polypropylene collection/sampling tubes while, to date, no broad comparison of these types of tubes has been conducted. In this study, we first compared, as part of a real clinical workflow, the impact of four different collection tubes on the CSF concentration of Aβ peptides (Aβ42, Aβ40) and total (hTau) and phosphorylated (P-Tau181P) tau proteins measured using routine ELISA kits. We then extended this study to 11 polypropylene tubes used by different clinical laboratories, and investigated their plastic polymer composition using differential scanning calorimetry and Fourier Transformed Infrared spectroscopy. Significant concentration variations linked solely to the use of different types of tubes were observed. This was particularly marked for Aβ peptides, with >50% disparity occurring in less than five minutes. Polymer composition analysis revealed that most polypropylene tubes were in fact copolymers with at least polyethylene. There was no clear correlation between tube composition and pre-analytical behavior. Our results show that the use of polypropylene tubes does not guarantee satisfactory pre-analytical behavior. They also point to collection/sampling tubes being a major pre-analytical source of variability that could impact the significance of AD biological diagnosis.
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http://dx.doi.org/10.3233/JAD-2012-120361DOI Listing
December 2012

d-Serine diffusion through the blood-brain barrier: effect on d-serine compartmentalization and storage.

Authors:
Pierre Pernot Caroline Maucler Yannick Tholance Natalia Vasylieva Gabriel Debilly Loredano Pollegioni Raymond Cespuglio Stéphane Marinesco

Neurochem Int 2012 Jun 23;60(8):837-45. Epub 2012 Mar 23.

Lyon Neuroscience Research Center, Plate-forme technologique AniRA-Neurochem, Team WAKE, Lyon F-69000, France.

d-Serine is a co-agonist of N-methyl-d-aspartate (NMDA) receptors. It has been implicated in the etiology of schizophrenia and has shown efficacy as an adjuvant to reduce positive and negative symptoms of schizophrenia. In addition, d-serine can modulate cognition in animals when administered alone. However, the neurochemical effects of exogenous d-serine on extra- and intra-cellular d-serine brain levels are poorly understood. In this study, we used both high performance liquid chromatography (HPLC) and enzyme-based microelectrode biosensors to quantify d-serine in the rat brain. We demonstrated levels of 2.3-2.8μM in the extracellular medium, 4μM in plasma and 188pmol/mg in brain tissue samples. An intraperitoneal (i.p.) d-serine injection (1g/kg) produced a slow increase in extracellular d-serine concentration in the cortex despite a surge in d-serine up to 13mM in the plasma, indicating poor diffusion through the blood-brain barrier. Using the respective volume fractions of blood, extracellular and intracellular spaces published in the literature, we estimated that d-serine intracellular stores represented more than 99% of total d-serine. These intracellular stores almost doubled 3h after d-serine administration. Overall, our data indicate that d-serine administration increases brain extra- and intra-cellular concentrations despite weak diffusion through the blood-brain barrier. These results pave the way for a better understanding of the neurochemical mechanisms by which d-serine administration modulates cognition.
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http://dx.doi.org/10.1016/j.neuint.2012.03.008DOI Listing
June 2012

Cerebrospinal fluid collection tubes: a critical issue for Alzheimer disease diagnosis.

Authors:
Armand Perret-Liaudet Mathieu Pelpel Yannick Tholance Benoit Dumont Hugo Vanderstichele Willy Zorzi Benaissa ElMoualij Susanna Schraen Olivier Moreaud Audrey Gabelle Eric Thouvenot Catherine Thomas-Anterion Jacques Touchon Pierre Krolak-Salmon Gabor G Kovacs Arnaud Coudreuse Isabelle Quadrio Sylvain Lehmann

Clin Chem 2012 Apr 8;58(4):787-9. Epub 2012 Feb 8.

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http://dx.doi.org/10.1373/clinchem.2011.178368DOI Listing
April 2012

Decreased sAβPPβ, Aβ38, and Aβ40 cerebrospinal fluid levels in frontotemporal dementia.

Authors:
Audrey Gabelle Stéphane Roche Christian Gény Karim Bennys Pierre Labauge Yannick Tholance Isabelle Quadrio Laurent Tiers Baptiste Gor Justine Boulanghien Chloé Chaulet Alain Vighetto Bernard Croisile Pierre Krolak-Salmon Armand Perret-Liaudet Jacques Touchon Sylvain Lehmann

J Alzheimers Dis 2011 ;26(3):553-63

Centre Mémoire Ressources Recherche Montpellier, Centre Hospitalier Universitaire de Montpellier, Hôpital Gui de Chauliac, Montpellier cedex 5, France.

To improve the etiological diagnosis of neurodegenerative dementias like Alzheimer's disease (AD) or frontotemporal dementia (FTD), we evaluated the value of individual and combined measurements of the following relevant cerebrospinal fluid (CSF) biomarkers: Tau, 181p-Tau, Aβ38, Aβ40, Aβ42, sAβPPα, and sAβPPβ. This study conducted in two centers included patients with FTD (n = 34), AD (n = 52), as well as a control group of persons without dementia (CTRL, n = 42). Identical clinical criteria and pre-analytical conditions were used while CSF biomarkers were measured using commercial single and multiplex quantitative immunoassays. Thorough statistical analyses, including ROC curves, logistic regressions, and decision trees, were performed. We validated in AD the specific increase of p-Tau levels and the decrease of Aβ42 levels, two biological hallmarks of this disease. Tau concentrations were highest in AD and intermediate in FTD when compared to CTRL. The most interesting results were obtained by focusing on amyloid biomarkers as we found out in FTD a significant decrease of sAβPPβ, Aβ38, and Aβ40 levels. Aβ38 in particular was the most useful biomarker to differentiate FTD subjects from the CTRL population. Combining p-Tau and Aβ38 led us to correctly classifying FTD patients with sensitivity at 85% and specificity at 82%. Significant changes in amyloid biomarkers, particularly for Aβ38, are therefore seen in FTD. This could be quite useful for diagnosis purposes and it might provide additional evidence on the interrelationship between Tau and AβPP biology which understanding is essential to progress towards optimal therapeutic and diagnostic approaches of dementia.
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http://dx.doi.org/10.3233/JAD-2011-110515DOI Listing
January 2012

In vivo demonstration of amyloid burden in posterior cortical atrophy: a case series with PET and CSF findings.

Authors:
Maïté Formaglio Nicolas Costes Jérémie Seguin Yannick Tholance Didier Le Bars Isabelle Roullet-Solignac Bernadette Mercier Pierre Krolak-Salmon Alain Vighetto

J Neurol 2011 Oct 10;258(10):1841-51. Epub 2011 Apr 10.

Department of Neurology, Service de Neurologie D, Hospices Civils de Lyon, Hôpital Neurologique, 59 boulevard Pinel, 69003, Lyon, France.

Our objective was to evaluate amyloid deposition in posterior cortical atrophy (PCA), using both cerebrospinal fluid (CSF) biomarker analysis and amyloid imaging. Five PCA patients, selected based on their neuropsychological profile and atrophic changes in posterior regions on MRI, underwent CSF analysis. CSF amyloid-beta 1-42, total tau, and phosphorylated tau at threonine 181 levels were determined. They also had positron emission tomography (PET) with Pittsburgh Compound B ([(11)C]PIB). [(11)C]PIB ratio images were assessed with visual, regional and voxel-based analyses and compared to eight typical Alzheimer's disease (AD) patients and eight controls. The biological profile in the five PCA patients, resulting from CSF and [(11)C]PIB images analysis, was consistent with AD. Individual comparisons of PCA patients' [(11)C]PIB images with the AD group with Statistical Parametric Mapping (SPM) revealed a distinctive posterior uptake in four out of the five patients showing increased amyloid deposition in occipital, temporal, and/or parietal regions. ROI group analysis showed a tendency for higher amyloid deposition in occipital and temporal regions. However, this pattern was not found with SPM group analysis when the global level of [(11)C]PIB uptake was used as a covariate. Our results indicate that amyloid burden can be demonstrated in vivo in PCA suggesting a diagnosis of AD. PCA patients may present a higher global amyloid load than AD that was not related to age at onset, disease severity, disease duration, or educational level in our study. Combined CSF and PET biomarkers seem helpful for in vivo diagnosis of this focal syndrome with underlying AD pathology.
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http://dx.doi.org/10.1007/s00415-011-6030-0DOI Listing
October 2011

Analytical validation of microdialysis analyzer for monitoring glucose, lactate and pyruvate in cerebral microdialysates.

Authors:
Yannick Tholance Gleicy Barcelos Isabelle Quadrio Bernard Renaud Frederic Dailler Armand Perret-Liaudet

Clin Chim Acta 2011 Mar 24;412(7-8):647-54. Epub 2010 Dec 24.

HCL, Centre de Biologie et de Pathologie Est, Laboratoire de Neurobiologie, Lyon, France.

Background: Cerebral microdialysis is a valuable tool for neurochemical monitoring of acute brain injury. We performed an independent analytical validation of glucose, lactate and pyruvate methods on the new ISCUS(flex) new analyzer developed by CMA Microdialysis.

Methods: Evaluation of analytical parameters included limit of detection, limit of quantification, linearity, intra- and inter-assay imprecision expressed as the coefficient of variation (CV), recovery, inter-sample and inter-reagent contamination, drug and bilirubin interferences, sample stability, method comparison.

Results: Linearity ranges were 0.1-25 mmol/L, 0.2-12 mmol/L and 19-1500 μmol/L for glucose, lactate and pyruvate respectively. For critical threshold, intra- and inter-assay CVs were 3.1/4.5% for glucose (1 mmol/L), 3.5/4% for lactate (4 mmol/L) and 3.3/4.3% for pyruvate (100 μmol/L). Inter-assay CVs for lactate/pyruvate (LPR) and lactate/glucose (LGR) ratios were 5.9% and 6.0% respectively. For glucose, lactate, pyruvate, LPR and LGR, the reference change values (RCV) were 20%, 26%, 20%, 27% and 28% respectively. Practically, variations below 27% between two successive LPR values could not be interpreted as significant.

Conclusion: These data prove that ISCUS(flex) has the qualities required for clinical application in neuro-intensive care. Correct clinical interpretation of data need the implementation of a strict quality control program and strong cooperation between clinicians and biologists.
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http://dx.doi.org/10.1016/j.cca.2010.12.025DOI Listing
March 2011

Correlations between soluble α/β forms of amyloid precursor protein and Aβ38, 40, and 42 in human cerebrospinal fluid.

Authors:
Audrey Gabelle Stéphane Roche Christian Gény Karim Bennys Pierre Labauge Yannick Tholance Isabelle Quadrio Laurent Tiers Baptiste Gor Chloé Chaulet Alain Vighetto Bernard Croisile Pierre Krolak-Salmon Jacques Touchon Armand Perret-Liaudet Sylvain Lehmann

Brain Res 2010 Oct 14;1357:175-83. Epub 2010 Aug 14.

Centre Mémoire Recherche Ressources Montpellier, Hôpital Gui de Chauliac, CHU de Montpellier, 34025 Montpellier cedex 5, France.

Cerebrospinal fluid (CSF) biomarkers are now widely used for diagnosis of Alzheimer disease (AD) in atypical clinical forms, for differential and early diagnosis, or for stratification of patients in clinical trials. Among these biomarkers, different forms of amyloid peptides (Aβ) produced by the cleavage of a transmembrane precursor protein called APP (amyloid precursor protein) have a major role. Aβ peptides exist in different length the most common ones having 40 (Aβ40), 42 (Aβ42), or 38 (Aβ38) amino acids in length. APP processing by gamma-secretase releases also an amino-terminal secreted fragment called sAβPP-beta while an alternative nonamyloidogenic cleavage of APP, through an alpha-secretase, liberates another fragment called sAβPP-alpha. To decipher the molecular and pathological mechanisms leading to the production and the detection of these entities is essential for the comprehension and the prevention of AD. In this report, we present the results of the multiplex measurement of CSF Aβ38, Aβ40, Aβ42, sAβPP-alpha, and sAβPP-beta in 60 patients mostly with dementia eventually segregated between neurochemical dementia diagnostic (NDD) positive and negative groups. The NDD classification was based on our routine Tau, P-tau(181), and Aβ(42) cutoff values. We confirmed previous findings regarding the correlation between sAβPP-alpha and sAβPP-beta, as well as the potential interest of these new biomarkers. We also studied the correlation between sAβPPs and Aβ peptides, as well as between Aβ peptides themselves. We observed a strong correlation between Aβ38 and sAβPP-beta which suggested that the production of this peptide was in direct relation with β secretase activities. We also reported a strong correlation between Aβ38 and Aβ40, while Aβ42 was correlated to these fragments only in nonpathological situations. These results enlighten the complex relationships between these molecular markers in both physiological and pathological situations. Our results are important for the further use of these analytes for AD diagnosis as well as for validating the cell biological hypotheses of APP processing and Aβ fragment production.
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http://dx.doi.org/10.1016/j.brainres.2010.08.022DOI Listing
October 2010