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Review
. 2018 Nov 14;10(11):1765.
doi: 10.3390/nu10111765.

Gut Microbiota and Their Neuroinflammatory Implications in Alzheimer's Disease

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Free PMC article
Review

Gut Microbiota and Their Neuroinflammatory Implications in Alzheimer's Disease

Vo Van Giau et al. Nutrients. .
Free PMC article

Abstract

The bidirectional communication between the central nervous system (CNS) and the gut microbiota plays a pivotal role in human health. Increasing numbers of studies suggest that the gut microbiota can influence the brain and behavior of patients. Various metabolites secreted by the gut microbiota can affect the cognitive ability of patients diagnosed with neurodegenerative diseases. Nearly one in every ten Korean senior citizens suffers from Alzheimer's disease (AD), the most common form of dementia. This review highlights the impact of metabolites from the gut microbiota on communication pathways between the brain and gut, as well as the neuroinflammatory roles they may have in AD patients. The objectives of this review are as follows: (1) to examine the role of the intestinal microbiota in homeostatic communication between the gut microbiota and the brain, termed the microbiota⁻gut⁻brain (MGB) axis; (2) to determine the underlying mechanisms of signal dysfunction; and (3) to assess the impact of signal dysfunction induced by the microbiota on AD. This review will aid in understanding the microbiota of elderly people and the neuroinflammatory roles they may have in AD.

Keywords: Alzheimer’s disease; MGB axis; germ-free animal; gut microbiota; neurodegenerative diseases; probiotic.

Conflict of interest statement

There are no conflicts of interest to declare.

Figures

Figure 1
Figure 1
Bidirectional signaling between the gastrointestinal tract and the brain is regulated at the neural, hormonal, and immunological levels.
Figure 2
Figure 2
A schematic of the hypothetical chain of events via which brain infection may lead to pathological amyloid-β peptide (Aβ) plaque formation in the brain. The amyloid precursor protein (APP) is processed by secretases into different peptides, including Aβ. The gut microbiota plays a significant role in the development of Alzheimer’s disease (AD) since Aβ functions as an antimicrobial peptide via oligomerization and plaque formation, trapping invading microorganisms, including bacteria, fungi, viruses, and protist parasites (detailed in Table 2). Aβ plaque formation in response to infection could result in a neuroinflammatory effect of microbiota on AD and neurodegeneration due to collateral damage in plaque-surrounding tissue.

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