Investigating the Potential Roles of Environmental Exposures on the Pathology of Amyotrophic Lateral Sclerosis by Overlap Analysis.

Amyotrophic Lateral Sclerosis (ALS) is a progressive neurodegenerative disease causing motor neuron loss. 90-95% of ALS cases are sporadic, and the interplay of genetic predispositions and environmental exposures is essential in ALS pathology. Several neurotoxic exposures, such as smoking, pesticides, and organic solvents, have been implicated as affecting the risk of ALS. However, it is unclear how these exposures impact specific cellular mechanisms and influence ALS risk. We investigated the potential mechanisms of toxicity of diesel exhaust, toluene, pesticides, and smoking on ALS pathology through a bioinformatics approach. We retrieved the gene sets targeted by these environmental exposures, and the gene sets involved in ALS-associated biological processes. We performed overlap analysis to assess the statistical significance of the overlap between the gene sets associated with environmental exposures and those linked to ALS. Response to oxidative stress, synaptic signaling, lipid metabolic process, cellular oxidant detoxification, and regulation of gliogenesis significantly overlapped with the gene sets targeted by each of the four environmental exposures. Contrarily, chaperone-mediated autophagy, DNA repair, and regulation of action potential, significantly overlapped only with the gene sets targeted by diesel exhaust, pesticides, and toluene, respectively. Finally, transport across the blood-brain barrier, vesicle-mediated transport, actin filament-based transport, autophagy, transport to the Golgi and subsequent modification of proteins, metabolism of lipids, regulation of neurotransmitter receptor levels, and axon guidance significantly overlapped only with the gene set targeted by tobacco smoke pollution. This study aims to investigate the molecular relationships between neurotoxic exposures and ALS by overlap analysis, providing a framework that can be applied to investigate other exposure-disease interactions.