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. 2017 Jun 20:9:195.
doi: 10.3389/fnagi.2017.00195. eCollection 2017.

16S rRNA Next Generation Sequencing Analysis Shows Bacteria in Alzheimer's Post-Mortem Brain

David C Emery  1 , Deborah K Shoemark  2 , Tom E Batstone  3 , Christy M Waterfall  3 , Jane A Coghill  3 , Tanya L Cerajewska  4 , Maria Davies  4 , Nicola X West  4 , Shelley J Allen  1
Affiliations

16S rRNA Next Generation Sequencing Analysis Shows Bacteria in Alzheimer's Post-Mortem Brain

David C Emery et al. Front Aging Neurosci. .

Abstract

The neurological deterioration associated with Alzheimer's disease (AD), involving accumulation of amyloid-beta peptides and neurofibrillary tangles, is associated with evident neuroinflammation. This is now seen to be a significant contributor to pathology. Recently the tenet of the privileged status of the brain, regarding microbial compromise, has been questioned, particularly in terms of neurodegenerative diseases. It is now being considered that microbiological incursion into the central nervous system could be either an initiator or significant contributor to these. This is a novel study using 16S ribosomal gene-specific Next generation sequencing (NGS) of extracted brain tissue. A comparison was made of the bacterial species content of both frozen and formaldehyde fixed sections of a small cohort of Alzheimer-affected cases with those of cognitively unimpaired (normal). Our findings suggest an increase in bacterial populations in Alzheimer brain tissue compared with normal.

Keywords: 16S rRNA; Alzheimer’s disease (AD); bacteria; human microbiome; next generation sequencing (NGS).

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Figures

Figure 1
Figure 1
Correlation of total bacterial reads with (A) post-mortem delay (PMD; in hours) and (B) age (in years) n = 6 C; n = 8 Alzheimer’s disease (AD). (C,D) Phylum level comparison of bacterial populations in frozen and formalin-fixed, paraffin-embedded (FFPE) samples from control (C) n = 8; AD n = 8. (C) shows percentage composition (D) shows bacterial sequence reads.
Figure 2
Figure 2
Summary of data at the family level expressed in bacterial sequence read counts. (A) Bacterial reads in control (n = 8) and AD (n = 8) samples. Legend is given in same order as shown in the bars (p. is phylum, f. is family). (B–G) Selected individual bacteria representing major components at the family level with p. Firmicutes f. Staphylococcaceae; p. Actinobacteria f. Corynebacteriaceae, showing higher levels in AD but p. Proteobacteria f. Methylobacteriaceae distributed across both AD and control samples.
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