Amyloidogenic Peptides in Human Neuro-Degenerative Diseases and in Microorganisms: A Sorrow Shared Is a Sorrow Halved?

Abstract

The term “amyloid” refers to proteinaceous deposits of peptides that might be generated from larger precursor proteins e.g., by proteolysis. Common to these peptides is a stable cross-β dominated secondary structure which allows self-assembly, leading to insoluble oligomers and lastly to fibrils. These highly ordered protein aggregates have been, for a long time, mainly associated with human neurodegenerative diseases such as Alzheimer’s disease (Amyloid-β peptides). However, they also exert physiological functions such as in release of deposited hormones in human beings. In the light of the rediscovery of our microbial commensals as important companions in health and disease, the fact that microbes also possess amyloidogenic peptides is intriguing. Transmission of amyloids by iatrogenic means or by consumption of contaminated meat from diseased animals is a well-known fact. What if also our microbial commensals might drive human amyloidosis or suffer from our aggregated amyloids? Moreover, as the microbial amyloids are evolutionarily older, we might learn from these organisms how to cope with the sword of Damocles forged of endogenous, potentially toxic peptides. This review summarizes knowledge about the interplay between human amyloids involved in neurodegenerative diseases and microbial amyloids.

Bidirectional effect of Triphala on modulating Gut-brain axis to improve cognition in the Murine Model of Alzheimer’s disease

“…Neurogenesis, an important mechanism for brain development, is closely associated with hippocampus-mediated learning and memory in the adult DG. These neurons also receive abundant cholinergic innervation, and cholinergic neurotransmitters released from cholinergic neurons are known to play a key role in memory-related circuits in the brain [11]. One such neurotransmitter, Ach, is synthesized from choline and acetyl coenzyme A by ChAT and plays a critical role in learning and memory.…”

Bidirectional Effect of Triphala on Modulating Gut‐Brain Axis to Improve Cognition in the Murine Model of Alzheimer's Disease

“…These neurons also receive abundant cholinergic innervation, and cholinergic neurotransmitters released from cholinergic neurons are known to play a key role in memory‐related circuits in the brain. [ 69 ] One such neurotransmitter, Ach, is synthesized from choline and acetyl coenzyme A by ChAT and plays a critical role in learning and memory. The duration of Ach action depends on the activity of AchE, which hydrolyzes and clears Ach released from the presynaptic membrane.…”

Influence of Acetylcholine Esterase Inhibitors and Memantine, Clinically Approved for Alzheimer’s Dementia Treatment, on Intestinal Properties of the Mouse

“…Nevertheless, memantine has been reported to exhibit anti-aggregation properties on A-beta [43]. Comparably to A-beta, some compounds of bacterial biofilms present amyloidogenic properties such as curli [44]. Therefore, interaction of the drug with this bacterial protein secreted during biofilm formation is in principle conceivable.…”