Microbiome to Systemic Disease I Flashcards by ava mondschein

What does “The Superorganism” mean?

the human body isn’t just made up of human cells — it’s also home to trillions of bacteria, especially in the gut microbiome and together, these human and microbial components function almost like one integrated organism

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What is a Holobiont?

a host organism (like a human) plus all the symbiotic microbes that live in or on it — including bacteria, fungi, viruses, and archaea

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What is the Microbiome?

collection of all microorganisms (like bacteria, fungi, viruses) living in a particular environment — like your gut, skin, or mouth — along with all their genes

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what modern day technological tools allow scientists to study microbes?

nucleic acid sequencing
- Sanger sequencing – the older, slower method
- Next generation sequencing (NGS) – faster, more powerful, and widely used today

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what are the characteristics of Sanger sequencing?

highly accurate (99.99%)
slow, expensive
can only process one DNA sequence at a time
long reads (up to 1500bp)
expensive

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what are the characteristics of Next Generation sequencing?

lower accuracy
cheap and automated
massively parallel – millions of sequences per run
short reads (80-600bps): not anymore

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what is the goal of the Human Microbiome Project and what does it study?

comprehensively study and map the microbiome (all microbes and their genes) at 18 different body sites, including:
15 sites common to both men and women: Nose (1), Mouth (9), Skin (4), GI tract (1) and 3 extra sites in women: Urogenital tract (vagina)

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What did the Human Microbiome Project discover about microbial diversity in the body?

found that each body site has a unique mix of microbes

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what makes the oral microbiome a unique habitat?

contains unique features like dorsum of the tongue (top surface), teeth and nutrients (food, saliva, GCF)
it is a heterogenous environment
supports all major microbe types (bacteria mainly)

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what is the oral microbiome?

all microorganisms in a mouth and their collective genome that form complex yet stable communities that adhere to surfaces in mutualistic relation with the host

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what does the Human Oral Microbiome Database (HOMD) provide?

comprehensive curated information on bacteria in the human mouth and aerodigestive tract including pharynx, nasal passages, sinuses and esophagus

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how does the microbiome of the mouth vary?

Intra-individual: From one site in the mouth to another
Inter-individual: Between different people
Inter-ethnicity: Between people of different ethnic backgrounds

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what does a loss in microbial homeostasis cause?

overgrowth of pathogens

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what are the bacteria that are strongly linked to periodontitis?

Porphyromonas gingivalis
Tannerella forsythia
Treponema denticola

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what are the routes in which microbes from the oral cavity can travel?

Aspiration: into the respiratory tract
Ingestion: into the GI tract
Lymphatics: to lymph nodes
Nerves
Bloodstream (Bacteremia): transient and chronic bacteremia

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what is transient bacteremia?

short-term presence of bacteria in blood → may cause mucosal injury

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what is chronic bacteremia?

ongoing bacterial presence (like in periodontitis) → linked to systemic inflammation and diseases

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What are the key inflammatory mediators released during periodontitis?

IL-1, IL-6, and TNF-α that trigger the liver to produce acute phase reactants

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What is the liver’s response to inflammatory mediators in periodontitis?

It produces acute phase proteins like C-reactive protein (CRP), serum amyloid A, and fibrinogen, contributing to systemic inflammation

How are diabetes and periodontitis related?

bidirectional relationship—uncontrolled diabetes is a known risk factor for periodontitis, and periodontitis can worsen glycemic control and increase the risk of diabetic complications

What is the impact of treating periodontitis on diabetes?

Periodontal treatment is associated with a 0.4% reduction in HbA1C levels over 3 months, indicating improved blood sugar control

wehat are the key mechanisms linking diabetes to Periodontitis?

AGE/RAGE Interaction
Upregulated Cytokine Production
Altered PMN (Polymorphonuclear) Cell Function
Altered Apoptosis

what are the two main bacteria genus that are linked to periodontitis and diabetes risk?

actinomyces
atopobium

what interleukin is associated with inducing a harmful microbiome?

IL-17

What is the relationship between periodontitis and atherosclerotic cardiovascular disease (ACVD)?

Strong epidemiological evidence shows that periodontitis is an independent risk factor for ACVD and may contribute to systemic inflammation that promotes cardiovascular disease

What cardiovascular benefits are linked to periodontal treatment?

Moderate evidence shows reduction in inflammatory biomarkers (e.g., CRP, IL-6, TNF-α, TG, TC, fibrinogen) improves endothelial function

Epidemiological evidence shows a significant association between periodontitis and increased risk of

cardiovascular diseases and stroke

what does periodontal treatment reduce in the body?

CRP levels, IL-6 levels, TNF-α levels, fibrinogen, triglycerides and cholesterol

how is carotid artery thickness (cIMT) affected by improved periodontal health?

- improvement in gum disease (periodontal disease, PD) is linked to a bigger drop in artery wall thickness - reduced number of disease-causing bacteria leads to a larger decrease in artery wall thickness

which bacteria have been frequently detected in atherosclerotic plaques?

A. actinomycetemcomitans, P. gingivalis, and F. nucleatum, T. Forsythia

what is the role of oral bacteria in controlling blood pressure?

Oral bacteria help convert dietary nitrate into nitrite, which is then reduced in the blood to nitric oxide—a molecule that promotes vasodilation and helps regulate blood pressure

what is the most effective nitrate reducing bacteria?

Neisseria flavescens

How does poor oral health increase the risk of pneumonia in elderly or ICU patients?

Poor oral health is linked to a higher risk of hospital-acquired pneumonia (HAP), especially ventilator-associated pneumonia (VAP), and aspiration pneumonia—due to high plaque, colonization by pathogens, dental caries, and periodontitis

How would you reduce oral microbial load to lower pneumonia risk?

mechanical cleaning and topical antibiotics/antiseptics helps decrease the risk of aspiration pneumonia in the elderly and HAP in ICU patients

what is the main oral hygiene intervention that significantly reduces the risk of respiratory infections?

use of antiseptics, especially chlorhexidine, is associated with a statistically significant reduction in infection risk with Chlorhexidine at a 2% concentration appearing to be the most effective

what are the mechanisms of how periodontal disease can contribute to respiratory infections?

- Dental plaque can harbor respiratory pathogens like P. aeruginosa and S. aureus. - Aspiration of oral bacteria (P. gingivalis, F. nucleatum, C. gracilis, P. oralis) can reach the lungs. - Enzymes from gum disease help bacteria stick to airways. - Inflammation from the gums may alter respiratory tissues, making infection easier.

What cancers are associated with severe periodontitis or tooth loss?

Oral cancer, upper gastrointestinal and gastric cancer, and pancreatic cancer

Which cancers have been linked to specific oral bacteria or microbiota changes?

Oral cancer, pancreatic cancer, and colon cancer

How is periodontal therapy related to cancer risk?

Periodontal therapy is associated with a decreased risk of certain types of cancers

what bacteria species is linked to oral and pancreatic cancer?

Porphyromonas gingivalis

what bacteria species is linked to oral, pancreatic and colon cancer?

fusobacteria

what are the associated bacterial species linked to oral cancer?

- P. aeruginosa - Fusobacterium Nucleatum

are fungal species linked to oral cancer?

yes mostly hannaella gibberella candida

what is the mechanism for how oral bacteria contribute to the development of oral cancer?

Oral bacteria can promote cancer through five key mechanisms: - producing carcinogenic substances (like acetaldehyde), blocking apoptosis (natural cell death), stimulating cell proliferation, enabling cancer cell invasion, and causing chronic inflammation

what are the increased bacterial functions related to inflammation and virulence that are prevalent during oral cancer?

lipopolysaccharide production, chemotaxis, and motility suggesting a more aggressive and inflammatory oral bacteriome

what is the relationship between periodontitis and low birth weight, preterm birth and pre-eclampsia?

limited evidence for an association