Exploring Cerebrospinal Fluid IgG N-Glycosylation as Potential Biomarker for Amyotrophic Lateral Sclerosis
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Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease for which the existing candidate biomarkers (neurofilaments) have low specificity. Changes in blood IgG N-glycosylation have been observed in several diseases, including ALS, whereas cerebrospinal fluid (CSF) IgG has been less studied. Here, we characterized N-glycans of CSF IgG from ALS patients in comparison with a control group of other neurological diseases. Cerebrospinal fluid was collected from patients with ALS (n = 26) and other neurological diseases (n = 10). N-Glycans were released from CSF purified IgG with peptide N-glycosidase F, labeled with 2-aminobenzamide and analyzed by NP-HPLC chromatography in combination with exoglycosidase digestion and MALDI-TOF mass spectrometry. The N-glycosylation profile of ALS CSF IgG consisted of diantennary N-glycans predominantly with proximal fucose and some bisecting GlcNAc; agalacto-, mono-, and digalactosylated as well as α2,6-sialylated structures were detected. Differences between ALS and control patients were observed; most relevant was the increase in ALS CSF IgG of the level of galactosylated structures defined here as Gal-index (median 46.87 and 40.50% for ALS and controls, respectively; p = 0.006). The predictive value of the Gal-index (AUC = 0.792, p = 0.007) considering ROC analysis had potential utility as a diagnostic test for ALS and was comparable to that of phosphoneurofilament heavy chain (AUC = 0.777, p = 0.011), which was used as benchmark marker for our group of patients. The results provide the basis to further explore the potential of IgG N-glycan galactosylation as biomarker for ALS by using larger cohorts of patients and controls.
KeywordsAmyotrophic lateral sclerosis Biomarker Cerebrospinal fluid Glycoproteins Immunoglobulin G N-Glycosylation
This work was supported by the EU JPND project SOPHIA (JPND/0003/2011), Fundação para a Ciência e a Tecnologia (FCT); Portugal and Euronanomed 2 ERA-NET project GlioEx (ENMed/0001/2013), FCT, Portugal; iNOVA4Health Research Unit (LISBOA-01-0145-FEDER-007344), which is cofunded by FCT/Ministério da Ciência e do Ensino Superior, through national funds; and by FEDER under the PT2020 Partnership Agreement.
Compliance with ethical standards
Patients signed permission for biobank storage, and further studies were agreed by the local Ethic’s committee. The research was done in accordance with the Helsinki Declaration as revised in 2013 (www.wma.net/policies-post/wma-declaration-of-helsinki-ethical-principles-for-medical-research-involving-human-subjects).
- 7.Lehnert S, Costa J, de Carvalho M, Kirby J, Kuzma-Kozakiewicz M, Morelli C, Robberecht W, Shaw P et al (2014) Multicentre quality control evaluation of different biomarker candidates for amyotrophic lateral sclerosis. Amyotroph Lateral Scler Frontotemporal Degener 15:344–350. https://doi.org/10.3109/21678421.2014.884592 CrossRefGoogle Scholar
- 9.Oeckl P, Jardel C, Salachas F, Lamari F, Andersen PM, Bowser R, de Carvalho M, Costa J et al (2016) Multicenter validation of CSF neurofilaments as diagnostic biomarkers for ALS. Amyotroph Lateral Scler Frontotemporal Degener 17:404–413. https://doi.org/10.3109/21678421.2016.1167913 CrossRefGoogle Scholar
- 13.Arnold JN, Wormald MR, Sim RB, Rudd PM, Dwek RA (2007) The impact of glycosylation on the biological function and structure of human immunoglobulins. Annu Rev Immunol 25:21–50. https://doi.org/10.1146/annurev.immunol.25.022106.141702 CrossRefGoogle Scholar
- 14.Thompson E J (2005) Proteins of the cerebrospinal fluid 2nd edition London: Elsevier :p.16.Google Scholar
- 23.Goncalves M, De Carvalho M, Peixoto C, Alves P, Barreto C, Oliva A, Pinto S et al (2017) Phosphoneurofilament heavy chain and vascular endothelial growth factor as cerebrospinal fluid biomarkers for ALS. Amyotroph Lateral Scler Frontotemporal Degener 18:134–136. https://doi.org/10.1080/21678421.2016.1212894 CrossRefGoogle Scholar
- 29.Ticozzi N, Tiloca C, Mencacci NE, Morelli C, Doretti A, Rusconi D, Colombrita C, Sangalli D et al (2013) Oligoclonal bands in the cerebrospinal fluid of amyotrophic lateral sclerosis patients with disease-associated mutations. J Neurol 260:85–92. https://doi.org/10.1007/s00415-012-6589-0 CrossRefGoogle Scholar
- 33.Holland M, Yagi H, Takahashi N, Kato K, Savage CO, Goodall DM, Jefferis R (2006) Differential glycosylation of polyclonal IgG, IgG-Fc and IgG-Fab isolated from the sera of patients with ANCA-associated systemic vasculitis. Biochim Biophys Acta 1760:669–677. https://doi.org/10.1016/j.bbagen.2005.11.021 CrossRefGoogle Scholar