Clinical perspective on oxidative stress in sporadic amyotrophic lateral sclerosis

Abstract

Sporadic amyotrophic lateral sclerosis (ALS) is one of the most devastating neurological diseases; most patients die within 3 to 4 years after symptom onset. Oxidative stress is a disturbance in the pro-oxidative/antioxidative balance favoring the pro-oxidative state. Autopsy and laboratory studies in ALS indicate that oxidative stress plays a major role in motor neuron degeneration and astrocyte dysfunction. Oxidative stress biomarkers in cerebrospinal fluid, plasma, and urine are elevated, suggesting that abnormal oxidative stress is generated outside of the central nervous system. Our review indicates that agricultural chemicals, heavy metals, military service, professional sports, excessive physical exertion, chronic head trauma, and certain foods might be modestly associated with ALS risk, with a stronger association between risk and smoking. At the cellular level, these factors are all involved in generating oxidative stress. Experimental studies indicate that a combination of insults that induce modest oxidative stress can exert additive deleterious effects on motor neurons, suggesting that multiple exposures in real-world environments are important. As the disease progresses, nutritional deficiency, cachexia, psychological stress, and impending respiratory failure may further increase oxidative stress. Moreover, accumulating evidence suggests that ALS is possibly a systemic disease. Laboratory, pathologic, and epidemiologic evidence clearly supports the hypothesis that oxidative stress is central in the pathogenic process, particularly in genetically susceptive individuals. If we are to improve ALS treatment, well-designed biochemical and genetic epidemiological studies, combined with a multidisciplinary research approach, are needed and will provide knowledge crucial to our understanding of ALS etiology, pathophysiology, and prognosis.

Keywords: 3-NT; 3-nitrotyrosine; 4-hydroxy-2-nonenal; 8-oxo-deoxyguanosine; 8-oxodG; ALAD; ALS; ANG; ApoE; CNS; CSF; CTE; Disease prognosis; ER; Environmental epidemiology; F2-isoprostanes; FTD; FVC; Free radicals; GSH; HDL; HNE; IsoPs; LDL; MDA; MND; MT; NADPH; NOS; OXR1; Oxidative stress; PD; PON; Parkinson disease; Phenotypic variation; RNS; ROS; SMN; SNP; SOD1; Sporadic ALS; TAR DNA-binding protein; TBARS; TDP-43; VAPB; VCP; VCP, valosin-containing protein; VEGF; amyotrophic lateral sclerosis; angiogenin; apolipoprotein E; central nervous system; cerebrospinal fluid; chronic traumatic encephalopathy; endoplasmic reticulum; fALS; familial ALS; forced vital capacity; frontotemporal dementia; glutathione; high-density lipoprotein; low-density lipoprotein; malondialdehyde; metallothionein; motor neuron disease; nicotinamide adenine dinucleotide phosphate; nitric oxide synthetase; oxidation resistance 1; paraoxonase 1; reactive nitrogen species; reactive oxygen species; sALS; single-nucleotide polymorphism; sporadic ALS; superoxide dismutase 1; survival motor neuron; thiobarbituric acid-reactive substances; vascular endothelial growth factor; vesicle associated protein-associated protein B; δ-aminolevulinic acid dehydratase.