W5 Bacteria Pathogenesis Part 2

Question 1

Give 2 components of bacteria pathogenesis

Answer 1

1. Virulence factors that promote bacteria colonization
2. Virulence factors that damage the host cells

Question 2

List 3 ways bacteria damage the host cells

Answer 2

1. Production of cell wall component
2. Produce harmful exotoxins
3. Ability to induce autoimmune response

Question 3

What is PAMPs?

Answer 3

Pathogen-associated molecular patterns that binds to pattern recognition receptors (PRRs) on macrophage/host cells
- can synthesis and produce cytokines
- promote innate immune defense such as inflammation, phagocytosis, activation of complement and coagulation pathway

Question 4

What is proinflammatory cytokines and its examples?

Answer 4

Proinflammatory cytokines can promote inflammation
- Interleukin 1
- Interleukin 6
- Interleukin 8
- Tumor necrosis factor alpha

Question 5

What is the function of tumor necrosis factor alpha?

Answer 5

promote inflammation

Question 6

What is the function of interleukin-1?

Answer 6

activate complement pathway

Question 7

What is the function of interleukin-6 and interleukin 8?

Answer 7

activate coagulation pathway

Question 8

Give mechanisms of inflammation when injury/infected

Answer 8

1. Body defense cells and chemicals leave the bloods and migrate to injury sites
2. Proinflammatory cytokines and chemokines cause vasodilation
3. Increase blood flow and BV permeability
4. Permeability lead cross of white blood cells squeeze out of BV and migrate to the infection site
5. Cause inflammation

Question 9

What is Systemic Inflammatory Response Syndrome (SIRS)

Answer 9

excessive inflammatory response in body

Question 10

What is PAMPs examples for Gram Negative bacteria?

Answer 10

• lipopolysaccharide & peptidoglycans monomer

Question 11

How gram negative PAMPS work?

Answer 11

• release of endotoxins when undergo normal replication or lysed/degradation
• LPS/endotoxins bind to CD14/TLR-4 to promote macrophage to release proinflammatory cytokines
• ## proinflammatory cytokines such as IL-1, IL-6, IL-8 and TNF-alpha

Question 11

What is PAMPs examples for Gram Positive bacteria?

Answer 11

lipoteichoic acid
peptidoglycan cell wall fragments

Question 12

How gram positive PAMPS work? - Staphylococcus pneumonia

Answer 12

• lyse of bacteria in lungs cause release of lipoteichoic acid and peptidoglycan cell walls fragments
• bind to receptors on endothelial cells
• cause release of TNF-alpha, IL-1 and chemokines
• increase the permeability in the lungs
• serous fluid, RBC and WBC enter the lungs space
• prevent normal gas exchange

Question 13

What is PAMPs examples for Acid Fast bacteria?

Answer 13

Mycolic Acid
Peptidoglycan fragments (muramyl dipeptides)

Question 14

How acid fast PAMPS work? - Mycobacterium tuberculosis & mycobacterium leprae

Answer 14

• lyse of bacteria cause release of mycolic acid and muramyl dipeptides from acid fast cell walls
• bind to pattern recognition receptors
• activate macrophages to release cytokines (TNF-alpha)
• damage to lungs due to effect of TNF-alpha and lysosomal component from macrophages trying to kill the M. tuberculosis

Question 15

4 main types of exotoxins

Answer 15

1. Type I toxins (superantingen)
2. Type II toxins
3. Type III toxins
4. Toxins that damage the extracellular matrix (hyaluronidase & collagenase)

Question 16

What is superantigens?

Answer 16

Superantigens is Type I toxins that can overstimulated immune defense response by excessively activate the CD4+ T cells and cause excessive production of cytokine Interleukin-2 (IL-2)

Question 17

3 examples of superantigen

Answer 17

1. Toxic shock syndrome toxins - 1 (TSST-1)
2. Streptococcal pyrogenic exotoxin (Spe)
3. Staphylococcal enterotoxins (SE)

Question 18

What is Type II toxins?

Answer 18

damage the host cellular membrane

Question 19

2 categories of Type II toxins and its brief mechanism and example organism

Answer 19

1. Channel-forming toxins
   - Pore forming
   - Staphylococcus aureus
2. Toxins that damage the cell membrane
   - cause gas gangrene
   - Clostridium perfringens

Question 20

What is Type III toxins?

Answer 20

can exert intracellular toxins by entering the cytoplasm first

Question 21

Example of Type III toxins and its mechanism

Answer 21

A-B toxins
- A component to exert toxic effect
- B components is to binding to cell receptor
- A-B toxins enter thru endocytosis

Question 22

What are the examples of A-B toxins?

Answer 22

• Shiga toxins by Shigella spp
• Cholera toxin by V. cholera
• Helicobacter toxin by H. pylori
• Pertussis toxin by Bordetella pertussis
• Tetanus toxin by Clostridium tetani

Question 23

What is autoimmunity?

Answer 23

Body’s immune system mistakenly attack the body

Question 24

3 ways bacteria can trigger the autoimmunity

Answer 24

a. Induce the auto-reactive cytotoxic T lymphocytes

b. Produce cross reacting Ab

c. Stimulate the production of soluble immune complexes

Question 25

What is cross-reactivity?

Answer 25

When Ab is assigned to bind to other antigens, attack and bind to different antigens

Question 26

What is immune complexes

Answer 26

Complexes that consist of Ab and antigens

Question 27

How immune complexes can cause autoimmune response?

Answer 27

Soluble immune complexes can lodging in filtering units in kidney

• and activate complement pathway
• cause acute glomerulonephritis