Genomic and biochemical approaches in the discovery of mechanisms for selective neuronal vulnerability to oxidative stress

<p>Abstract</p> <p>Background</p> <p>Oxidative stress (OS) is an important factor in brain aging and neurodegenerative diseases. Certain neurons in different brain regions exhibit selective vulnerability to OS. Currently little is known about the underlying mechanisms of this selective neuronal vulnerability. The purpose of this study was to identify endogenous factors that predispose vulnerable neurons to OS by employing genomic and biochemical approaches.</p> <p>Results</p> <p>In this report, using <it>in vitro </it>neuronal cultures, <it>ex vivo </it>organotypic brain slice cultures and acute brain slice preparations, we established that cerebellar granule (CbG) and hippocampal CA1 neurons were significantly more sensitive to OS (induced by paraquat) than cerebral cortical and hippocampal CA3 neurons. To probe for intrinsic differences between <it>in vivo </it>vulnerable (CA1 and CbG) and resistant (CA3 and cerebral cortex) neurons under basal conditions, these neurons were collected by laser capture microdissection from freshly excised brain sections (no OS treatment), and then subjected to oligonucleotide microarray analysis. GeneChip-based transcriptomic analyses revealed that vulnerable neurons had higher expression of genes related to stress and immune response, and lower expression of energy generation and signal transduction genes in comparison with resistant neurons. Subsequent targeted biochemical analyses confirmed the lower energy levels (in the form of ATP) in primary CbG neurons compared with cortical neurons.</p> <p>Conclusion</p> <p>Low energy reserves and high intrinsic stress levels are two underlying factors for neuronal selective vulnerability to OS. These mechanisms can be targeted in the future for the protection of vulnerable neurons.</p

Relationship between Cerebrospinal Fluid Biomarkers for Inflammation, Demyelination and Neurodegeneration in Acute Optic Neuritis

BACKGROUND: Various inflammatory biomarkers show prognostic potential for multiple sclerosis (MS)-risk after clinically isolated syndromes. However, biomarkers are often examined singly and their interrelation and precise aspects of their associated pathological processes remain unclear. Clarification of these relationships could aid the appropriate implementation of prognostic biomarkers in clinical practice. OBJECTIVE: To investigate the interrelation between biomarkers of inflammation, demyelination and neurodegeneration in acute optic neuritis and to assess their association to measures of MS risk. MATERIAL AND METHODS: A prospective study at a tertiary referral centre from June 2011 to December 2012 of 56 patients with optic neuritis as a first demyelinating symptom and 27 healthy volunteers. Lumbar puncture was performed within 28 (median 16) days of onset. CSF levels of CXCL13, matrix metalloproteinase (MMP)-9, CXCL10, CCL-2, osteopontin and chitinase-3-like-1, myelin basic protein (MBP) and neurofilament light-chain (NF-L) were determined. MS-risk outcome measures were dissemination in space (DIS) of white matter lesions on cerebral MRI, CSF oligoclonal bands and elevated IgG-index. RESULTS: In the interrelation analysis the biomarkers showed close correlations within two distinct groups: Biomarkers of leukocyte infiltration (CXCL13, MMP-9 and CXCL10) were strongly associated (p<0.0001 for all). Osteopontin and chitinase-3-like-1 were also tightly associated (p<0.0001) and correlated strongly to tissue damage markers (NF-L and MBP). The biomarkers of leukocyte infiltration all associated strongly with MS-risk parameters, whereas CHI3L1 and MBP correlated with MRI DIS, but not with CSF MS-risk parameters and osteopontin and NF-L did not correlate with any MS-risk parameters. CONCLUSIONS: Our findings suggest two distinct inflammatory processes: one of leukocyte infiltration, represented by CXCL13, CXCL10 and MMP-9, strongly associated with and potentially predicting MS-risk; the other represented by osteopontin and CHI3L1, suggesting tissue damage-related inflammation, potentially predicting residual disabilities after attack and perhaps cumulative damage over time. These hypotheses should be further addressed in follow-up studies