Lecture 5

Question 1

Sugar substitutes may have negative effects on the gut microbiota

Answer 1

Sucralose, aspartame, and saccharin have been shown to disrupt the balance and diversity of gut microbiota. Rats given sucralose for 12 weeks had significantly higher proportions of Bacteroides, Clostridia, and total aerobic bacteria in their guts and a significantly higher faecal pH than those without sucralose. Mice given sucralose for six months had an increase in the expression in the gut of bacterial pro-inflammatory genes and disrupted faecal metabolites
Mice fed relatively low concentrations of two commonly used emulsifiers carboxymethylcellulose and polysorbate-80 showed reduced microbial diversity compared with mice not fed with emulsifiers. Bacteroidales and Verrucomicrobia were decreased and inflammation promoting Proteobacteria associated with mucus was enriched.

Question 2

High Fibre

Answer 2

High Fibre reduces risk of diabetes and heart disease

the gut microbiota composition, and in
turn, the metabolites produced by commensals affect the inflammatory response

Question 3

Cheese consumption

Answer 3

consumption beneficial resulting in increased Bifidobacteria which are known for their positive health benefits to their host through their metabolic activities. Decrease in Bacteroides and Clostridia, some strains of which are associated with intestinal infections. Overall increased production of SCFA and reduced production of TMAO

Question 4

avoiding gluten

Answer 4

increasing risk of heart disease, bc of the reduced consumption of whole grains

Question 5

Drugs ( laxatives, progesterone, TNF inhibitors and rupatadine)

Answer 5

major impact on community diversity and structure of the gut microbiota. Proton pump inhibitors alter the microbial community which could explain higher rates of gastrointestinal infection in people taking the drugs

Question 6

Infant gut microbiome

Answer 6

by 3 infant microbiomes are the same as adults

Question 7

. Butyrate

Answer 7

Butyrate is the main energy source for human colonocytes, can induce apoptosis of colon cancer cells, and can activate intestinal gluconeogenesis, having beneficial effects on glucose and energy homeostasis.
Butyrate is essential for epithelial cells to consume large amounts of oxygen through β oxidation, generating a state of hypoxia that maintains oxygen balance in the gut, preventing gut microbiota dysbiosis.

Question 8

propionate

Answer 8

transferred to the liver, where it regulates gluconeogenesis and satiety signalling through interaction with the gut fatty acid receptors

Question 9

. Acetate

Answer 9

essential metabolite for the growth of other bacteria it reaches the peripheral tissues where it is used in cholesterol metabolism and lipogenesis, and may play a role in central appetite regulation

Question 10

What SCFA’s control gut hormones and reduce apetite

Answer 10

Butyrate and propionate seem to control gut hormones and reduce apetite and reduce food intake in mice

Question 11

MEAT.

Answer 11

Trimethylamine production from dietary phosphatidylcholine and carnitine (from meat and dairy) depends on the gut microbiota and thus its amount in blood varies between people. Trimethylamine is oxidised in the liver to trimethylamine N-oxide, which is positively associated with an increased risk of atherosclerosis and major adverse cardiovascular events.

Question 12

Indolepropionic acid

Answer 12

is highly correlated with dietary fibre intake and has potent radical scavenging activity in vitro, which seems to reduce the risk of incidence of type 2 diabetes.

Question 13

Christensenella sp

Answer 13

was rare in
overweight people and when
given to germ free mice
prevented weight gain

Question 14

What can the human gut microbiota affect?

Answer 14

metabolism, nutrient absorption, immune function.

Question 15

Disruption of the microbiota can induce:

Answer 15

Disruption of this population has been implicated in many conditions and diseases, including examples such as obesity, inflammatory bowel disease and colorectal cancer

Question 16

Minipulation of the gut microbiota

Answer 16

it could treat obesity, inflammotory bowl disease and colerectal cancer
could change the diet (use probiotics) antimicrobial based intervention, probiotics and faecel microbiota transplantation

Question 17

Probiotics

Answer 17

Protect against cancer, inulin and other Ch2O sources plant storage compounds increase gas production named; defined as food components or ingredients that are not digestible by the human body but specifically or selectively nourish beneficial colonic micro-organisms

Question 18

Use of antibiotics to manipulate gut microbiome

Answer 18

vancomycin reduced G+ and reduced weight

gain in high fat diet.

Question 19

Probiotics

Answer 19

mostly G+ lactobacilli and bifidobacteria, impact immune response to pathogens in
gut, lower plasma insulin, cholesterol and reduced weight gain.
Faecal microbiota transplant- restore balanced microbiota .

Question 20

Gut commensal influence on the immune response.

Answer 20

• The molecules expressed and produced by commensals affect the inflammatory response and Treg differentiation.
• Dietary fiber influences
  the gut microbiota composition, and in
  turn, the metabolites produced by commensals affect the inflammatory response
  and Treg differentiation/accumulation,
  Aldha1: aldehyde dehydrogenase isoform
  1A1; DC: dendritic cells; Gadd45a: growth arrest and DNA damage inducible alpha;
  GPR: G-protein-coupled receptor; NLR4: NLR family CARD domain containing 4;
  PSA-OMV: polysaccharide A-associated outer membrane vesicles; SAA: serum
  amyloid A; SCFAs: short-chain fatty acids; TLR: Toll-like receptor; Treg: regulatory T
  cells.

Question 21

Bacterial Accsess to the epithelium

Answer 21

Both bacterial pathogens and commensals have the ability to cross the mucus layer and access the gut epithelium. Lectins and other mucus binding proteins facilitate initial interactions with the mucus layer. Mucinases and proteases are used to degrade mucus allowing bacteria to eat their way through, whereas some pathogens use flagella to swim through the viscous mucus allowing bacteria to eat their way through whereas some pathogens use flagella to swim through the viscous mucus. Toll like receptor 5 sensing o f flagellin effectively leads to inhibition of flagellum biosynthesis for most bacteria in the gut.

Question 22

Microbiota and immunity

Answer 22

The symbiosis between the microbiota and its mammalian host encompasses multiple relationships, including mutualistic, parasitic, and commensal. The capacity of a given microbe, including those composing the microbiota, to trigger or promote disease is highly contextual, and some microbes can shift from mutualist to commensal to parasite according to the state of activation of the host, co-infection, or localization. Commensals can control microbes with pathogenic potential (as normal constituent of the microbiota or acquired) via distinct mechanisms. Commensals can compete for nutrients and produce antimicrobial molecules and metabolites that affect the survival and virulence of pathogens. Commensals can promote the production of antimicrobial peptides by epithelial cells and reinforce tight junctions. Finally, commensals
can modulate the function of dendritic cells and other innate cells both locally and systemically in a manner that promotes the induction of effector T and B cells responses against pathogens. When uncontrolled, this adjuvant property of the microbiota can promote inflammatory and autoimmune disorders.

Question 23

Probiotics

Answer 23

Live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Examples include strains of the genera Bifidobacterium and Lactobacillus. Probiotics can have multiple interactions with the host, including competitive inhibition of other microbes, effects on mucosal barrier function and interaction with antigen presenting dendritic cells.

Question 24

probiotics

Answer 24

A selectively fermented ingredient that results in specific changes in the composition and/or activity of the GI microbiota, thus conferring benefit(s) upon host health. Prebiotics are usually non-digestible carbohydrates, oligosaccharides or short polysaccharides, with inulin,
oligofructose, galactofructose, galacto-oligosaccharides and xylo-oligosaccharides being some of the most intensively studied.

Question 25

Post Biotics

Answer 25

Key signalling molecules and bacterial components impact on immune modulation.

Question 26

Benefits of lactobacilli

Answer 26

prevents: diarrhoea, necrotising enterocolitis, acute upper respiratory tract infections, pulmonary exacerbations in children with cystic fibrosis, and eczema in children.
Probiotics improve cardiometabolic parameters and reduced serum concentration of C reactive protein in patients with type 2 diabetes.

There are concerns that most microbe supplements are unable to establish themselves in the gut and fail to exert an effect on the resident community. But probiotics can affect health independently of the gut microbiota through direct effects on the host; for example, through immune modulation or the production of bioactive compounds. The therapeutic effect of probiotic supplementation has been studied in a broad range of diseases.

Question 27

Faecal microbiota transplantation (FMT)

Answer 27

Many concordant studies, including a recently published randomised trial have shown that faecal microbiota transplantation (FMT) is effective for treating recurrent forms ofClostridium difficileinfection (CDI). The use of FMT in this indication is recommended in the most recent Europeanand North Americanguidelines.

Question 28

Could probiotics be the next big thing in acne and rosacea treatments?
SCHAUMBURG, Ill. (Feb. 3, 2014) —

Answer 28

Dermatologists encouraged by early research showing link between probiotic use and clearer skin in acne and rosacea patientsOVERVIEW: In recent years, probiotics have become synonymous with helping maintain good digestive health. Whether as live active cultures found in some yogurts or as daily supplements, probiotics are live, “friendly” bacteria that may benefit a person’s health. Now, emerging research is finding that the benefits of probiotics may extend beyond the digestive tract to the skin. In fact, skin prone to acne or rosacea has shown improvement with daily probiotic use, giving dermatologists reason to consider supplementing traditional acne therapy with a dose of this beneficial bacteria.

Question 29

Oral Microbiome

Answer 29

Streptococci (especially Streptococcus mutans) and lactobacilli have long been recognized as pathogens that are associated with caries; however, more recent molecular analyses have revealed the existence of a pathogenic community that includes non-streptococcal bacteria (for example, Bifidobacterium spp., Scardovia spp. and Actinomyces spp.) and fungi (for example, Candida albicans
If sugar consumption is low and infrequent, the microbial communities on teeth remain stable and, despite being able to produce acids that demineralize enamel, the episodic pH decrease is neutralized by saliva, which restores and maintains the mineralization of enamel. Frequent exposure to fermentable carbohydrates, microorganisms become embedded in an EPS-rich biofilm matrix while constantly producing acids that are physically protected from rapid buffering by saliva. Localized regions of low pH within biofilms formed on tooth surfaces continue to select for aciduric microorganisms. If the biofilm is not removed and frequent sugar consumption continues, a prolonged and repeated state of acidification ensues (which can be exacerbated by dysfunction in salivary secretion or composition), disrupting the homeostatic mineral balance towards enamel demineralization