Antibody profiling identifies novel antigenic targets in spinal cord injury patients

Abstract

BackgroundRecent evidence implicates antibody responses as pivotal damaging factors in spinal cord injury (SCI)-induced neuroinflammation. To date, only a limited number of the antibody targets have been uncovered, and the discovery of novel targets with pathologic and clinical relevance still represents a major challenge.MethodsIn this study, we, therefore, applied an unbiased, innovative and powerful strategy, called serological antigen selection (SAS), to fully identify the complex information present within the antibody repertoire of SCI patients.ResultsWe constructed a high-quality cDNA phage display library derived from human spinal cord tissue to screen for antibody reactivity in pooled plasma samples from traumatic SCI patients (n = 10, identification cohort). By performing SAS, we identified a panel of 19 antigenic targets to which the individual samples of the plasma pool showed antibody reactivity. Sequence analysis to identify the selected antigenic targets uncovered 5 known proteins, to which antibody reactivity has not been associated with SCI before, as well as linear peptides. Immunoreactivity against 9 of the 19 novel identified targets was validated in 41 additional SCI patients and an equal number of age- and gender-matched healthy subjects. Overall, we found elevated antibody levels to at least 1 of the 9 targets in 51 % of our total SCI patient cohort (n = 51) with a specificity of 73 %. By combining 6 of these 9 targets into a panel, an overall reactivity of approximately half of the SCI patients could be maintained while increasing the specificity to 82 %.ConclusionsIn conclusion, our innovative high-throughput approach resulted in the identification of previously unexplored antigenic targets with elevated immunoreactivity in more than 50 % of the SCI patients. Characterization of the validated antibody responses and their targets will not only provide new insight into the underlying disease processes of SCI pathology but also significantly contribute to uncovering potential antibody biomarkers for SCI patients.

Elevated Autoantibodies in Subacute Human Spinal Cord Injury Are Naturally Occurring Antibodies

“…So far, significant increased levels of AAb have been described against myelin basic protein (MBP), ganglioside GM1 (GM1), myelin galactocerebroside (GalC), glial fibrillary acidic protein (GFAP) and collapsing response mediator protein-2 (CRMP-2) in humans after SCI ( 1 , 2 , 4 , 11 – 13 ). Also, by incubating patient blood sera with a phage display of a human spinal cord cDNA expression library, a set of five AAbs against 26S proteasome non-ATPase regulatory subunit 4 (PSMD4), glyceraldehyde-3-phosphate dehydrogenase (G3P), myeloma-overexpressed gene protein (MYEOV2), protein S100-B (S100B) and adipocyte enhancer-binding protein 1 (AEBP1) has been proposed to be enriched in patients, although individually none of these AAbs reached statistical significance ( 14 ). However, the complete repertoire of AAb specificities induced after SCI remains unknown because most studies have been done by selecting the antigenic determinants to be tested “ a priori ,” not by unguided discovery methods.…”

Novel maternal autoantibodies in autism spectrum disorder: Implications for screening and diagnosis

“…A custom-made cDNA phage display library was generated from mRNA expressed in human fetal brains, which thus forms an in vitro representation of the antigens expressed during human fetal brain development. The use of the SAS technology has proven to be a successful method for identifying novel antibody biomarkers in other diseases such as rheumatoid arthritis, axial spondylarthritis, multiple sclerosis and spinal cord injury ( Somers et al, 2008 , 2011 ; Palmers et al, 2016 ; Quaden et al, 2020 ). This is the first time that human fetal brain antigens have been used in a comprehensive screening for targets of m-ASD antibodies, as previous studies have screened starting from protein extracts of Rhesus macaque fetal brain ( Braunschweig et al, 2013 ), or used a candidate-based approach ( Brimberg et al, 2016 ).…”

Lesional Antibody Synthesis and Complement Deposition Associate With De Novo Antineuronal Antibody Synthesis After Spinal Cord Injury

“… 25 Future studies are needed to identify specific cognate surface epitopes of neurons, synapses, and glia. 34 In analogy to paraneoplastic syndromes, 14 the emerging autoimmunity directed against spinal cord and DRG epitopes suggests the existence of functional relevant neuronal paratraumatic autoimmune syndromes.…”