Biochemical biomarkers of disease in a deeply-phenotyped cohort of patients with motor neuron disease

Background

Motor neuron disease is a fatal, neurodegenerative condition in which patients suffer
progressive weakness due to loss of motor neurons. Biomarker research deepens disease
understanding through exploration of pathophysiological mechanisms which, in turn,
highlights targets for novel therapies.
Aims and objectives
a) To recruit patients with motor neuron disease and control subjects, collate clinical
information and collect biosamples. This will form a comprehensive database of well-
phenotyped patient information and biosamples for analysis. b) To explore the
concentrations of 3-nitrotyrosine in cerebrospinal fluid (CSF) and serum across the subject
cohorts. A sensitive biomarker of oxidative stress will be of use in experimental medicine
studies aimed at reducing this mechanism of nerve injury. c) To explore the inflammatory
milieu present in serum and CSF using multiplex enzyme-linked immunosorbent assays
(ELISAs). d) To develop Raman spectroscopy as a tool to analyse biofluid samples.

Results
The AMBRoSIA study proved to be a successful recruitment method, with a high proportion
of subjects donating the full complement of clinical information and biosamples. 3-
nitrotyrosine was not reliably detected in these samples. Neurofilament light chain emerged
as a consistently useful biomarker in terms of differentiating patients from controls and
clinical correlations. Provisional analyses yielded several inflammatory biomarkers that were
differentially expressed; many of these did not survive conservative statistical corrections or
repeated experimentation, however. Plasma monocyte chemoattractant protein-1 (MCP-1),
interferon-gamma (IFN-γ) and CSF tyrosine-protein kinase receptor (TIE-2) were
differentially expressed, and serum amyloid-A (SAA) inversely correlated with disease
severity. Raman spectroscopy was moderately successful in demonstrating the ability to
differentiate between subject groups.

Conclusions
This body of work supports systematic patient recruitment and collection of clinical data and
biosamples to identify biomarkers. electrochemiluminescent-ELISA is a sensitive and
capable multiplex platform for analysis of biofluids. Raman spectroscopy is a promising
technique and further development is required. Additional multi-centre recruitment and
sample testing is still required for the development and validation of biomarkers in motor
neuron disease.