Non-uinform gut microbiota alteration patterns associated with therapeutic outcomes in an Alzheimer's disease animal model

Abstract

Background: Dysbiosis of gut microbiota is associated with the progression of beta-amyloid (Aβ) pathology in Alzheimer’s disease (AD). We aimed to identify uniform Aβ-responsible gut microbiota status as possible guideline for gut microbiota manipulation and the prediction of outcomes of microbiota targeted treatments. Six months old APP/PS1 mice from the same genetic background, housing and feeding conditions were then daily gavage with Metformin, peptides WN5 or PW5 to manipulate the gut microbiota for 12 weeks. Aβ pathology and gut microbiota were then explored and compared. Results: Fecal microbiota transplantation (FMT) from a 16 month old APP/PS1 mouse reconstituted the gut microbiota towards the donor and increased Aβ pathology in APP/PS1 mouse model. Metformin, peptides WN5 and PW5 all attenuated Aβ-plaque formation in APP/PS1 mouse model but each was associated with distinct gut microbiota status. No uniform gut microbiota pattern associated with Aβ pathology was found among different gut microbiota-targeted treatments. Conclusion: We found no uniform gut microbiota status associated with Aβ pathology suggesting gut microbiota status is not a suitable biomarker for AD diagnosis and treatment predictions. Alteration of gut microbiota in itself may not be sufficiently directly related to functional outcomes and might only be a shadow of deeper molecular mechanisms not fully understood. The findings here strongly suggested that the significance of gut microbiota alteration in disease pathology and treatment may have so far been over claimed and that interpretation of gut microbiota data should be done with utmost caution.