BMS3020 L17 Infection Pathogenesis 12/11/18
BMS3020 CHRONIC DISEASE
LECTURE 17 – Infection Pathogenesis
KEY CONCEPT/ ESSAY QUESTION: Chronic Infection = Chronic
Inflammation?
Chronic inflammation is the main driver of chronic disease but not all chronic infection cause
prolonged inflammation in sickness.
Infection, Inflammation and Sickness
- Tissue Damage: Redness, heat, swelling, pain and dysfunction of the inflamed organs
- Feel sick: Neurological effects including pain, lethargy and depression
- Are they connected?
Pathogens can
damage tissues in
a variety of
different ways
DIRECT:
1. Exotoxin production – Can
kill or damage tissues/cells
1. Endotoxin – Excite
inflammation which will kill
or damage the cells
2. Direct cytopathic effect –
More for virus action
INDIRECT:
1. Immune complexes – Large Ag can bind many antibodies which cross link and deposit in small
capillaries, can lead to kidney disease
2. Anti-host antibody – Antigen can have similarities to host-antigen, so the antibody can cross
react and attack self-cells
3. Cell-mediated immunity – NK cell and CD8 T cell killing, lysing of cells and tissue damage
- Tissue damage is a driving force for inflammation under infection conditions
- Healthy tissue gets initial viral infection and the immune response causes tissue damage
- But hopefully, if the immune response can control
viral loads there is tissue repair, immune memory
and pathogen clearance
- However, if IR fails to control pathogen, it can cause
pathogen persistence which have many mechanisms
(above) to drive chronic inflammation
- This chronic inflammation causes chronic immune
activation (adaptive immune response)
- Inflammation becomes more and more severe as
tissue repair (still occurring) is unsuccessful due to
continuous damage and remodelling process
1
BMS3020 CHRONIC DISEASE
LECTURE 17 – Infection Pathogenesis
KEY CONCEPT/ ESSAY QUESTION: Chronic Infection = Chronic
Inflammation?
Chronic inflammation is the main driver of chronic disease but not all chronic infection cause
prolonged inflammation in sickness.
Infection, Inflammation and Sickness
- Tissue Damage: Redness, heat, swelling, pain and dysfunction of the inflamed organs
- Feel sick: Neurological effects including pain, lethargy and depression
- Are they connected?
Pathogens can
damage tissues in
a variety of
different ways
DIRECT:
1. Exotoxin production – Can
kill or damage tissues/cells
1. Endotoxin – Excite
inflammation which will kill
or damage the cells
2. Direct cytopathic effect –
More for virus action
INDIRECT:
1. Immune complexes – Large Ag can bind many antibodies which cross link and deposit in small
capillaries, can lead to kidney disease
2. Anti-host antibody – Antigen can have similarities to host-antigen, so the antibody can cross
react and attack self-cells
3. Cell-mediated immunity – NK cell and CD8 T cell killing, lysing of cells and tissue damage
- Tissue damage is a driving force for inflammation under infection conditions
- Healthy tissue gets initial viral infection and the immune response causes tissue damage
- But hopefully, if the immune response can control
viral loads there is tissue repair, immune memory
and pathogen clearance
- However, if IR fails to control pathogen, it can cause
pathogen persistence which have many mechanisms
(above) to drive chronic inflammation
- This chronic inflammation causes chronic immune
activation (adaptive immune response)
- Inflammation becomes more and more severe as
tissue repair (still occurring) is unsuccessful due to
continuous damage and remodelling process
1
