Inflammation Flashcards
What are the main characteristics of the immune system?
- Present from birth
- Immediate and non-specidic
- No enhancement/memory
What are the 3 main components of the inflammation response?
- chemotaxis (recruitment of cells)
- phagocytosis
- degranulation
What are the 4 main steps of inflammation?
1) piercing of the epithelium causes the release of histamines, increasing blood flow to the area
2) Causes capillaries to leak, releasing phagocyte and clotting factors
3) phagocytes engulf bacteria, dead cells and cellular debris
4) Platelets move out of the capillaries to seal the wounded area
What is diapedesis?
- The process by which neutrophils exit the capillaries
- Neutrophils have integrins on cell surface which binds to selectins on capillary walls forming strong attachments
- Histamines allow them to exit
Describe the structure of selectins?
- Transmembrane proteins with a carbohydrate bindiing site at the amino end
- Varibale number of consensus repeats (C) as well as carbohydrate binding (L) and epidermal growth factors (EGF) domains at the N-terminus
What are the 3 types of selectins and where are they found?
P - platelets
E - endothelial cells
L - leucocytes
What are the properties of integrins?
2 subunits: alpha and beta 3 beta type: 1. Binds to extracellular matrix 2. Adheres leucocytes to endothelium 3. mediates interaction of platelets neutrophils at inflammation
What are the 5 main steps of phagocytosis?
chemotaxis, attachment, injestion, fusion and killing
What is oponisation?
The coating of a pathogen with opsonin which stimulates uptake by phagocytes
Describe the formation of a phagosome
- Pathogen binds to phagocyte receptor stimulating cytoskeleton reorganisation
- Enzymes dictate conformational changes to membrane and cytoskeletal mesh
- Phagosome fuses with granules allowing access to particles inside
What is the pattern recognition concept ?
That conserved microbial features are detected by immunocytes to initiate an immune response
What is the danger concept?
Immune system responds to danger signals emitted by tissues after microbial infection/stress
What are PAMPs?
- Pathogen associated molecular patterns
- Glycorporteins/other molecules which are unique to bacterial surfaces (e.g flagellin, peptidoglycan)
- Bind to receptor PRRs (patern recognition receptos) which can be lectins or toll-like receptors
What are toll-like receptors?
- Essential for sensing pathogens and initiating the innate immune response
- 10 different families with different biding specifities which can recognise endogenous and exogenous signals and work together to maximise efficiency
What are anti-microbial proteins?
Small proteins with broad proteins, released from granules which usually permeabilize the cell wall
Describe the process of O2 dependent killing
- During the uptake of a pathotagen there is an activation of membrane bound NAHPH oxidase through the phox enzyme complex, RAC and GTP
- Generates toxic oxygen metabolites such as suberoxide and hydrogen peroxide
- Calyzed back to harmless compounds by antioxidants
What is necrosis?
- Unplanned harmful cell death due to interferance with energy supply or membrane damage
- Leads to cell swells, distortion of organelles and release of cytoplasmic contents
What is apoptosis?
- The natrual removal of unwanted/dangerous/diseased cells
- Also controls lymphocyte selection, immune cell lifespan and removes damaged tissue after injury
Describe the process of creation of neutrophil chromatin extracellular traps
- Under extreme conditions neutrophils can ‘self-sacrifice’ releasing a ‘net’ of chromatin
- Net becomes coated with antimicrobial surface markers which are targetted by proteins and cleaned up by macrophages
- Also induced activity of protein kinase C, pro-inflammatory factors and platelets
