TLR4 and amyotrophic lateral sclerosis: Despite the upregulation of the phagocytosis-related TREM2, TLR4 and RAGE surface receptors, microglia show a decreased ability to phagocytose and propensity to cell senescence upon exosome interaction, thus favoring the involvement of mSOD1 exosomes in the ALS onset and progression, whose precise mechanism of action requires additional studies.