Non-cell autonomous autophagy in amyotrophic lateral sclerosis: A new promising target?

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative non-cell-autonomous disease with no cure, thus research is intensely focused on identifying pharmacological targets. Several studies aimed to clarify the pathogenic mechanisms and involvement in various cell types. A crucial factor in ALS is autophagy, which plays a key role in degrading intracellular protein aggregates. The connection between ALS and autophagy is reinforced by the fact that several genes mutated in ALS are linked to fundamental aspects of autophagy. The blockage of the autophagic flux was observed in ALS motor neurons, where it occurs earlier than in glia. However, the inconsistent effects of autophagy modulators in preclinical and clinical studies indicate the need for a deeper understanding of the role of autophagy in other cell types, such as astrocytes, microglia, and oligodendrocytes. Astrocytes and microglia are significantly impacted by autophagy dysregulation, contributing to neurodegeneration in both mouse and human-derived models. Autophagy is overactivated early in the disease, even before symptoms appear. This overactivation is influenced by the timing and specific tissue involved. It can alter cells' immunophenotype, favouring proinflammatory responses and affecting the cellular environment and autophagy in the surrounding cells. In contrast, oligodendrocytes show mild autophagic alterations. Additionally, sex hormones may affect proper autophagy function and ALS progression. The lack of information on how sex influences autophagy in glia highlights the need for more nuanced investigation into this mechanism. Future research should focus on these aspects, paving the way for personalised pharmacological approaches that consider the roles of cell types, time of intervention, and sex.