# data[].attributes.body
First to illustrate the effects of absence of gut microbiota on amyloid build-up

Successfully showed decreased levels of neuroinflammation in germ-free mice.

Identified strain of bacteria (Akkermansia) that may influence the development of Aβ amyloid build-up.

Adds support to notion that microbiota may affect progression of  neurodegenerative diseases.

Potential for development of novel AD prevention and treatment methods.

# data[].attributes.headline
What is Enzyme-Linked Immuno-Sorbent Assay (ELISA)?

# data[].attributes.subject
What is Enzyme-Linked Immuno-Sorbent Assay (ELISA)?

# data[].attributes.body
It is a biochemical technique that uses antibodies and color change to identify a substances.

But if you prefer watching videos, this is pretty helpful!

# data[].attributes.attachment_link.title
Enzyme-Linked Immunosorbent Assay (ELISA) - Multi-Lingual Captions

# data[].attributes.body
... But Still... It's Not Like One Can Just Weaponize Poop with Alzheimer's or Parkinson's Disease

# data[].attributes.headline
Colonization of GF-APPPS1 Mice with Microbiota Increases Pathology 

# data[].attributes.subject
Colonization of GF-APPPS1 Mice with Microbiota Increases Pathology 

# data[].attributes.body
Immunostaining using Iba-1 for microglia showed an overall decrease in cortical neuroinflammation in GF-APPPS1 mice

For both 3.5 month and 8 month old GF mice, there was a decrease in Iba-1 positive immunostaining compared to control.

Pro-inflammatory cytokines interleukin-1β detected using ELISA increased with age in CONVR-APPPSI but not in GF-APPPS1 mice; it was 36% lower at 8 month of age in GF mice.

# data[].attributes.headline
Decreased Cortical Neuroinflammation in GF-APPPS1 Mice

# data[].attributes.subject
Decreased Cortical Neuroinflammation in GF-APPPS1 Mice

# data[].attributes.headline
Germ-Free (GF) Mice vs. Specific Pathogen-Free Mice (SPF, control) Microglia Morphology and Function

# data[].attributes.subject
Germ-Free (GF) Mice vs. Specific Pathogen-Free Mice (SPF, control) Microglia Morphology and Function

# data[].attributes.body
Germ-free mice exhibit increased microglia segments, branching and process length (11).

The germ-free mouse microglia generally hold a more immature morphological state and an upregulation of proliferation markers is evident. Germ-free mice further exhibit decreased microglia inflammatory responses (11).

Fung TC et al. Nat Neurosci. 2017 Feb;20(2):145-155.

# data[].attributes.body
The authors were the first to examine the progression of amyloid buildup in the absence of gut microbiota in GF-APPPS1 mice, and from the results they suggest that different compositions of microbiota in the gut influence amyloid buildup in the brain. Specifically, the authors note a class of bacteria, Akkermansia, which they suggest may be involved in the development of amyloid plaques in the brain. They hypothesize that the low levels of Akkermansia in CONVR-APPPS1 and COLOAD-APPPS1 results in enhanced entry of inflammatory compounds from the gut, as Akkermansia has been shown to improve the integrity of the gut barrier (10). In addition, the authors suggest that alterations in the activity of microglia in the GF-APPPS1mice may also be among the reasons as to why they have lower amyloid levels than CONVR-APPPS1 mice. The altered immune responses in the brain of the GF-APPPS1 mice, including a decrease in inflammation and changes in inflammatory cytokine levels, are consistent with results from previous experiments on germ-free mice (8, 9). For example, germ-free mice have been shown to display impaired immune responses, increase in markers of immaturity in microglia, and dysregulated microglia morphology (8,9). In addition, not only does gut microbiota influence the brain in mice, recently it has also been shown that intake of probiotics in fermented milk products influences activity of the brains of healthy women (16). The authors conclude that the findings hold potential for the development of prevention and treatment methods for neurodegenerative diseases.

Cryan, J. F. & Dinan, T. G. Nat Rev Gastroenterol Hepatol. 2015 Sep;12:494-6.

# data[].attributes.body
Sequencing of bacterial 16S rRNA genes from fecal samples

CONVR-APPPS1 mice show more pronounced shifts in gut    microbiota composition from 1 month to 3.5 month to 8 month-old compared CONVR-WT.

At 8 month of age, transgenic APPPS1 mice showed significant reductions in Firmicutes, Verrucomicrobia, Proteobacteria and Actinobacteria.

Concurrent increase in Bacteriodetes and Tenericutes in the phylum level.

In the genus level, Allobaculum and Akkermansia were decreased compared to the wildtype.

These differences were not due to metabolic parameters such as food intake and body weight, since those variables remained constant.

# data[].attributes.body
Hemi-brain sections with cortex and hippocampus were stained with Thioflavin T (ThT) depicting amyloid plaque load (bright green spots)

GF-APPPS1 showed reduced levels of Aβ and reduced Aβ deposition in the brain compared to CONVR-APPPS1.

# data[].attributes.attachment_link.readable_text
Source: Lund University.
New research from Lund University in Sweden has shown that intestinal bacteria can accelerate the development of Alzheimer's disease. According to the researchers behind the study, the results open up the door to new opportunities for preventing and treating the disease
Because our gut bacteria have a major impact on how we feel through the interaction between the immune system, the intestinal mucosa and our diet, the composition of the gut microbiota is of great interest to research on diseases such as Alzheimer's. Exactly how our gut microbiota composition is composed depends on which bacteria we receive at birth, our genes and our diet.

By studying both healthy and diseased mice, the researchers found that mice suffering from Alzheimer's have a different composition of gut bacteria compared to mice that are healthy. The researchers also studied Alzheimer's disease in mice that completely lacked bacteria to further test the relationship between intestinal bacteria and the disease. Mice without bacteria had a significantly smaller amount of beta-amyloid plaque in the brain. Beta-amyloid plaques are the lumps that form at the nerve fibres in cases of Alzheimer's disease.

To clarify the link between intestinal flora and the occurrence of the disease, the researchers transferred intestinal bacteria from diseased mice to germ-free mice, and discovered that the mice developed more beta-amyloid plaques in the brain compared to if they had received bacteria from healthy mice.

"Our study is unique as it shows a direct causal link between gut bacteria and Alzheimer's disease. It was striking that the mice which completely lacked bacteria developed much less plaque in the brain", says researcher Frida Fåk Hållenius, at the Food for Health Science Centre.

"The results mean that we can now begin researching ways to prevent the disease and delay the onset. We consider this to be a major breakthrough as we used to only be able to give symptom-relieving antiretroviral drugs."

About this Alzheimer's disease research article

Funding: The research is a result of an international collaboration between Associate Professor Frida Fåk Hållenius and doctoral student Nittaya Marungruang, both at the Food for Health Science Centre in Lund, and a research group at the Ecole Polytechnique Federale de Lausanne in Switzerland. The collaboration has now expanded to include researchers from Germany and Belgium in connection with receiving a SEK 50 million EU grant.

The researchers will continue to study the role of bacteria in the development of Alzheimer's disease, and test entirely new types of preventive and therapeutic strategies based on the modulation of the gut microbiota through diet and new types of probiotics.

Source: Frida Fåk Hållenius - Lund University
Image Source: NeuroscienceNews.com image is adapted from Lund University press release.
Original Research: Full open access research for "Reduction of Abeta amyloid pathology in APPPS1 transgenic mice in the absence of gut microbiota" by T. Harach, N. Marungruang, N. Duthilleul, V. Cheatham, K. D. Mc Coy, G. Frisoni, J. J. Neher, F. Fåk, M. Jucker, T. Lasser & T. Bolmont in Scientific Reports. Published online February 8 2017 doi:10.1038/srep41802

Cite This NeuroscienceNews.com Article

[cbtabs][cbtab title="MLA"]Lund University "Gut Bacteria May Play a Role in Alzheimer's Disease." NeuroscienceNews. NeuroscienceNews, 10 February 2017.
<https://neurosciencenews.com/microbiota-alzheimers-6096/>.[/cbtab][cbtab title="APA"]Lund University (2017, February 10). Gut Bacteria May Play a Role in Alzheimer's Disease. NeuroscienceNew. Retrieved February 10, 2017 from https://neurosciencenews.com/microbiota-alzheimers-6096/[/cbtab][cbtab title="Chicago"]Lund University "Gut Bacteria May Play a Role in Alzheimer's Disease." https://neurosciencenews.com/microbiota-alzheimers-6096/ (accessed February 10, 2017).[/cbtab][/cbtabs]
Abstract Reduction of Abeta amyloid pathology in APPPS1 transgenic mice in the absence of gut microbiota
Alzheimer's disease is the most common form of dementia in the western world, however there is no cure available for this devastating neurodegenerative disorder. Despite clinical and experimental evidence implicating the intestinal microbiota in a number of brain disorders, its impact on Alzheimer's disease is not known. To this end we sequenced bacterial 16S rRNA from fecal samples of Aβ precursor protein (APP) transgenic mouse model and found a remarkable shift in the gut microbiota as compared to non-transgenic wild-type mice. Subsequently we generated germ-free APP transgenic mice and found a drastic reduction of cerebral Aβ amyloid pathology when compared to control mice with intestinal microbiota. Importantly, colonization of germ-free APP transgenic mice with microbiota from conventionally-raised APP transgenic mice increased cerebral Aβ pathology, while colonization with microbiota from wild-type mice was less effective in increasing cerebral Aβ levels. Our results indicate a microbial involvement in the development of Abeta amyloid pathology, and suggest that microbiota may contribute to the development of neurodegenerative diseases.

"Reduction of Abeta amyloid pathology in APPPS1 transgenic mice in the absence of gut microbiota" by T. Harach, N. Marungruang, N. Duthilleul, V. Cheatham, K. D. Mc Coy, G. Frisoni, J. J. Neher, F. Fåk, M. Jucker, T. Lasser & T. Bolmont in Scientific Reports. Published online February 8 2017 doi:10.1038/srep41802

Feel free to share this Neuroscience News.

# data[].attributes.attachment_link.title
Gut Bacteria May Play a Role in Alzheimer's Disease - Neuroscience News

# data[].attributes.attachment_link.description
Source: Lund University. New research from Lund University in Sweden has shown that intestinal bacteria can accelerate the development of Alzheimer's disease.

# data[].attributes.body
For the purpose of studying complete depletion, they generated a germ-free version of the mouse model.

Was done using 4-6 weeks old female APPPS1 mice

Administering intraperitoneal injections to cause superovulation.

5 IU pregnant mare serum gonadotropin

5 IU of human chorionic gonadotropin

Paired with APPPS1 male

Embryos flushed and washed with an antibiotic cocktail

Pseudo-pregnate germ free NMRI recipient female under asceptic conditions.

A non-genetically engineered mouse strain.

Both CONVR and GF APPPS1 are age-matched with controls and raised in ventilated cages and flexible film isolators respectively.

# data[].attributes.headline
Reduced Amyloid Accumulation in GF-APPPS1 Mice

# data[].attributes.subject
Reduced Amyloid Accumulation in GF-APPPS1 Mice

# data[].attributes.headline
Reduced Cerebral Aβ42 Levels in GF-APPPS1 Mice

# data[].attributes.subject
Reduced Cerebral Aβ42 Levels in GF-APPPS1 Mice

# data[].attributes.body
Western blot was used to detect Aβ proteins

In both CONVR and GF-APPPS1 mice, Aβ levels increased from 3.5 month to 8 month old.

In comparison to CONVR-APPPS1, the GF animals had significantly lower cerebral Aβ42, suggesting lower AD pathology.

# data[].attributes.headline
CONVR-APPPS1 Mice Display Alterations in Gut Microbiota Composition

# data[].attributes.subject
CONVR-APPPS1 Mice Display Alterations in Gut Microbiota Composition

# data[].attributes.headline
Conventionally-Raised APPPS1 Mice (CONVR APPPS1)

# data[].attributes.subject
Conventionally-Raised APPPS1 Mice (CONVR APPPS1)

# data[].attributes.body
Group of mouse models that exhibit parenchymal plaque deposition by the age of 6 months

Have signs of significant neurodegeneration. This makes them ideal for studying Alzheimer's Disease pathophysiology.

# data[].attributes.body
Oral gavage of GF WT with CONVR-APPPS1 and CONVR-WT control is missing, this is very important in confirming that both genetics and environmental triggers are needed in order for pathophysiology to develop.

"I mean if giving someone an oral garage can give them Alzheimer's Disease a few years down the line, then we would have weaponized poop!" - Ju, 2017

Correlation study but no clear causation established or mechanism established

Authors suggest some possible mechanisms as to how gut microbiota could influence amyloid buildup, but no experiments conducted to support hypothesis

No structural or behavioural tests conducted

Behavioural/cognitive and structural consequences of amyloid development – key components of Alzheimer’s disease – not examined

No morphology or specific microglia stain with Iba1

Iba1 stain does not show different states, such as ramified or activated, the microglia are in

No rescue experiments conducted

If progression of amyloid buildup truly caused by gut microbiota, then rescue experiments – colonizing mice then making them germ free again – should show reversed effects

# data[].attributes.body
To study the impact of complete intestinal microbe depletion on AD pathogenesis.

Study the link between microbiota and cerebral Aβ deposition using:

Conventionally raised AD mouse model

Germ-free mouse model

# data[].attributes.body
Mutations of β-secretase pathway by increasing cleavage of precursor protein (APP) leading to a highly fibrillogenic protein and increase in  β42/40 ratio (6).

Mutations of presenilin-1 or 2 (PSEN1 or PSEN2), the proteolytic component of the γ-secretase complex also increase the β42/40 ratio (6).

Current models of AD mostly use transgenic mice expressing human amyloid APP in combination with human PSEN1 (1,6,12).

Mouse APP has a 3 amino acid variance of Aβ which results in lack of amyloid plaque formation in WT mice (6).

Aβ and pro-inflammatory factors lead to neuroinflammation through activation of microglia and eventual neuronal damage

# data[].attributes.body
Alzheimer’s disease (AD) is progressive neurodegenerative disease characterized by deficits in memory, attention, planning, finding words. Furthermore, patients experience confusion & spatial disorientation (1).

Accumulation of amyloid β (Aβ) plaques extracellularly; phosphorylated tau protein neurofibrillary tangles (NTFs) intracellularly (1,6,12).

# data[].attributes.body
1.  Ashe KH. Alzheimer’s Disease: Transgenic Mouse Models. Encyclopedia of Neuroscience. 2009; 283 – 287.

2. Bravo JA, Forsythe P, Chew MV, Escaravage E, Savignac HM, Dinan TG, Bienenstock J, Cryan JF. Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve. Proc Natl Acad Sci U S A. 2011 Sep 20;108(38):16050-5.

3. Collins SM, Surette M, Bercik P. The interplay between the intestinal microbiota and the brain. Nat Rev Microbiol. 2012 Nov;10(11):735-42.

4. Cryan JF, Dinan TG. Gut microbiota: Microbiota and neuroimmune signalling-Metchnikoff to microglia. Nat Rev Gastroenterol Hepatol. 2015 Sep;12(9):494-6.

5. De-Paula VJ1, Radanovic M, Diniz BS, Forlenza OV. Alzheimer's disease. Subcell Biochem. 2012;65:329-52.

6. Drummond E, Wisniewski T. Azheimer's disease: experimental models and reality. Acta Neuropathol. 2017 Feb;133(2):155-175.

7. Elias JA, Lee CG, Zheng T, Ma B, Homer RJ, Zhu Z. New insights into the pathogenesis of asthma. J Clin Invest. 2003 Feb;111(3):291-7.

8. Erny, D., Hrabě de Angelis, A. L., Prinz, M. Communicating systems in the body: how microbiota and microglia cooperate. Immunology, 2017 Jan; 150: 7–15.

9. Erny D, Hrabě de Angelis AL, Jaitin D, Wieghofer P, Staszewski O, David E, Keren-Shaul H, Mahlakoiv T, Jakobshagen K, Buch T, Schwierzeck V, Utermöhlen O, Chun E, Garrett WS, McCoy KD, Diefenbach A, Staeheli P, Stecher B, Amit I, Prinz M. Host microbiota constantly control maturation and function of microglia in the CNS. Nat Neurosci, 2015 Jun; 18: 965-977.

10. Everard A1, Belzer C, Geurts L, Ouwerkerk JP, Druart C, Bindels LB, Guiot Y, Derrien M, Muccioli GG, Delzenne NM, de Vos WM, Cani PD. Cross-talk between Akkermansiamuciniphila and intestinal epithelium controls diet-induced obesity. Proc NatlAcadSci U S A. 2013 May 28;110(22):9066-71.

11. Fung TC, Olson CA, Hsiao EY. Interactions between the microbiota, immune and nervous systems in health and disease. Nat Neurosci. 2017 Feb;20(2):145-155.

12. Götz J, Ittner LM. Animal models of Alzheimer's disease and frontotemporal dementia. Nat Rev Neurosci. 2008 Jul;9(7):532-44.

13. Harach T, Marungruang N, Duthilleul N, Cheatham V, McCoy KD, Frisoni G, Neher JJ, Fåk F, Jucker M, Lasser T, Bolmont T. Reduction of Abetaamyloidpathology in APPPS1 transgenic mice in the absence of gut microbiota. SciRep. 2017 Feb 8;7:41802.

14. Pietronigro EC, Della Bianca V, Zenaro E, Constantin G. NETosis in Alzheimer'sDisease. Front Immunol. 2017 Mar 2;8:211.

15. Sandhu KV, Sherwin E, Schellekens H, Stanton C, Dinan TG, Cryan JF. Feeding the microbiota-gut-brain axis: diet, microbiome, and neuropsychiatry. TranslRes. 2017 Jan;179:223-244.

16. Tillisch K, Labus J, Kilpatrick L, Jiang Z, Stains J, Ebrat B, Guyonnet D, Legrain-Raspaud S, Trotin B, Naliboff B, Mayer EA. Consumption of Fermented Milk Product With Probiotic Modulates Brain Activity. Gastroenterology. 2013 Jun;144(7):1394-401.

17. VERSARPPS,. Flexible Film Isolator. 2017. Web. 28 Mar. 2017.

Videos

Annik Carson, Greg Brown and Mitchell Moffit "What If You Had A Second Brain?" AsapSCIENCE YouTube Channel, September 29, 2016. https://www.youtube.com/watch?v=T3Ftj5E90tY

Lund University “Gut Bacteria May Play a Role in Alzheimer’s Disease.” NeuroscienceNews. NeuroscienceNews, 10 February 2017.
<http://neurosciencenews.com/microbiota-alzheimers-6096/>

Nature Video "Inside Alzheimer’s disease." Nature Video YouTube Channel, January 3, 2017. https://www.youtube.com/watch?v=zTd0-A5yDZI

University of Michigan "Enzyme-Linked Immunosorbent Assay (ELISA) - Multi-Lingual Captions." openmichigan YouTube Channel, December 23, 2010. https://www.youtube.com/watch?v=RRbuz3VQ100

# data[].attributes.body
The authors should attempt to establish a clear mechanism behind how microglia activity influences amyloid buildup. Using short chain fatty acids (SCFA) the authors could examine the effects of restoring microglia activity in the brain of germ free mice, in which microglia activity has been shown to be impaired (8,9,11).

1. Cut vagus nerve (CNX) (2)

2. Introduce SCFA (microbiome metabolite) to restore microglia density and activation in GF-WT and GF-APPPS1 mice (11)

3. Measure changes in fatty acid and inflammatory composition to ensure desired effects were indeed induced (11)

4. Structural measures of dendrite growth and arborisation to test for morphological consequences of SCFA introduction

5. Novel object location and recognition tests to test for cognitive and behavioural consequences of SCFA introduction

Expected results:

If there is increase in pro-inflammatory cytokines due to SCFA introduction, then increase in plaque will be observed post-restoration with SCFA in the GF-APPPS1 mice but not in the GF-WT.

# data[].attributes.body
CONVR-APPPS1 mice display alterations in gut microbiota composition.

Both Aβ levels and deposition are reduced in GF-APPPS1 mice compared to CONVR-APPPS1 mice

Neuroinflammation changes in GF-APPPS1 transgenic mice

Colonization of GF-APPPS1 mice with microbiota increases Aβ pathology compared CONVR-APPPS1 and CONVR-WT mice

# data[].attributes.body
Colonization study was done using 4 month-old GF-APPPS1 mice

Given an oral gavage of either the gut microbiota of an aged (12 month-old) CONVR-WT or CONVR-APPPS1 mice

Named COLOWT-APPPS1 and COLOAD-APPPS1 respectively

Kept in a conventional environment for 8 weeks (COLOWT-APPPS1 and COLOAD-APPPS1 mice).

Bacterial 16S rRNA gene sequencing. Mice were analysed 8 weeks after the beginning of the colonization.

Plasma Aβ levels were detected using ELISA

Colonization of GF-APPPS1 mice with microbiota increased Aβ pathology. Aβ levels were higher overall.

Levels of Aβ42 in the colonized WT-APPPSI mice increased by 145% compared to control GF-APPPSI.

This suggests a link between microbiota and Aβ amyloidosis.

# data[].attributes.body
Microbiota is a collection of bacteria, viruses and fungi that can grow within an organism (3).

The gut and the brain communicate in a bidirectional manner, mainly through the vagus nerve (CNX) involving the central, autonomic and enteric nervous systems (3, 11, 15).

The microbiota-gut-brain axis consists of cellular signalling processes through secondary bacterial metabolites, metabolic precursors, immune signalling, vagus nerve signalling, and HPA axis activation (3,11,15).

The microbiota effects the formation of the blood-brain barrier, neurogenesis, microglia, myelination, neuron growth and survival (4,9).