Trehalose's untapped mechanisms in alzheimer's: gut-brain-autophagy signalling beyond the usual targets

Trehalose is a promising therapeutic candidate for Alzheimer's disease (AD) that is known to induce autophagy and facilitate misfolded proteins clearance such as amyloid-β and hyperphosphorylated tau. Despite there is emerging evidence that trehalose has a wider range of molecular mechanisms and thus has a greater neuroprotective profile.

To summarize the emerging molecular mechanisms underlying the neuroprotective effects of trehalose beyond classical autophagy and discuss its therapeutic potential in AD.

Published evidence from preclinical studies including in-vitro and in-vivo models, along with hypothetical and emerging findings from early clinical investigations was reviewed to evaluate the molecular mechanisms, therapeutic effects, and translational challenges associated with trehalose in AD.

In addition to classical autophagy signalling, recent studies have demonstrated that autophagy can also regulate the stability of neuronal membrane microdomains, prevent lipid bilayers disruption by amyloid proteins, and regulate stress granules dynamics that affect the function of RNA-binding proteins. Other discoveries indicate that interactions with nutrient-sensing pathways and glucose transporter systems that simulate metabolic stress, which may activate protective mechanisms separate from the inhibition of mTOR. Trehalose could also involve in lysosomal-autophagosome fusion and modulate the microglia and astrocytes activation, suggesting an important immunometabolic function. Trehalose often connects to the gut-brain axis and show their effect in gut microbiota composition, microbial metabolite signalling and gut barrier function. These effects can influence systemic inflammation, availability of short-chain fatty acids, bile acid profiles and vagus-mediated gut-to-brain communication, all of which can influence neuroinflammation networks in AD.

Although promising results have been reported, primarily from preclinical studies, with early human investigations now beginning to emerge, opportunities remain to address, such as poor oral bioavailability, penetration into the brain and long-term safety in elderly patients. Mechanistic dissection in multi-omics approaches, microbiome-stratified models and early-phase clinical testing are the areas that need to be targeted in future research. A broader understanding of the mechanisms of action of trehalose provides a good chance to reimagine its therapeutic implications and develop novel approaches to AD.