Acute and Chronic Inflammation Part 2 Flashcards
Recap the 5 steps of the inflammatory response
1. Recognition 2, Recruitment 3. Removal 4. Regulation 5. Resolution
What is removed in an inflammatory response?
The agent causing the injury
What is activated during the removal step of inflammation
Leukocytes are activated, with enhanced capability to carry out their functions
What are some of the function of leukocytes during the removal phase of inflammation?
- Phagocytosis
- Secretion of microbicidal substances to remove extracellular inflammatory agent
- Release of extracellular traps
- Amplification of inflammatory response
What is the release of extracellular traps called?
Netosis
Which cells carry out Netosis
Neutrophil attack cells
What happens to cells that carry out netosis?
They die
Briefly go though the stages of phagocytosis
check slide 6 pic
- Phagocytic receptors recognise microbes or dead cells
- Microbes bind to phagocyte receptors
- Phagocyte membrane zips up around the microbe engulfing it
4 The phagosome with the ingested microbe sudeswith a lysosome forming a phagolysosome - Microbe is killed by ROS and NO
- Microbe is degraded by lysosomal enzymes in rate phagolysosome
What happens in a respiratory burst?
Superoxide is produced by the oxidation of NADPH and can also be converted into hydrogen peroxide and then hypochlorite (by MPO in neutrophils + macrophages)
What can super oxide react or do?
Superoxide can react with nitric oxide to produce peroxynitrite
Go though some damage that pathogens can carry out
- Lipid perooxidation leading to membrane damage
- Protein modifications leading to breakdown and misfiling of protein
- DNA damage leading to mutations
What extracellular activity occurs in the bosy?
- Secretion of enzymes fro neutrophil azurophilic granule
- Release of lysosomal enzymes and ROS and NO during phaogcytisus
- Secretion of chemokine and cytokines to recruit and activate macrophages
- Netosis
What does the NET in NETosis stand for?
Neutrophil extraceullar traps
What os NETosis stimulated by?
Stimulated by microbes and inflammatory signals
Which blood cells are the most predominant during acute inflammation?
Our innate white blood cells (Neutrophils, macrophages)
What process occurs alongside phagocytosis?
Respiratory burst
What is thE outcome of the respiratory burst?
Reactive oxygen species are produced
These species can kill microbes BUT also cause damage to host cells
How can reactive oxygen species damage our host cells
- Can damage our membranes as lipid peroxidation occurs
- Proteins can be damaged so incorrect folding may occur
- Can cause break in our DNA
What can prolonged spells of inflammation lead to?
Cancer possibly due to t the fact that inflammation produced reactive oxygen species which can lead to breaks in our DNA
Give examples of some microbicidal substances that are produced during an inflammatory response
- Enzymes are secreted from neneutrophil azurophilic granules
- lysosomal enzymes, Reactive oxygen species and nitric oxide are produced during phagocytosis
- Chemokines and cytokines are secreted to recruit and activate macrophages
What is NETosis?
The generation of Neutrophil Extracellular Traps (NETs)
What is NETosis stimulated by?
Microbes and inflammatory signals
What happens in NETosis?
Neutrophils are stimulated to release Neutrophil Extracellular Traps (NETs)
What are Neutrophil Extracellular Traps (NETs) made of?
Made up of nucleosomal DNA and complex with our histories
How are Neutrophil Extracellular Traps (NETs) produced?
- Neutrophils are stimulated
- Results in the formation of NADPH-oxidase and reactive oxygen species produced
- PAD4 is activated
- Nucelar chromatin decondenses and the nuclear envelope integrity is lost
- Nuclear materia fills the cell and mixes with granule content
- Nuclear and granule membrane integrity is lost and the palsma membrane ruptures
- Nuclear chromatin associated with proteinases and hastens is released into the extracellular space (these are the NETs)
How do Neutrophil Extracellular Traps (NETs) aid inflammation?
Extruded DNA produced by neutrophils form a dense net of fibres which have microbicidal molecules attached to trap and destroy microbes.
Give examples of microbicidal molecules that are attached to Neutrophil Extracellular Traps (NETs)
- Elastase
- Myloperoxidase
- Cathespsin G
- Antimicrobial peptides (LL37)
- Proteinase 3
What happens to the neutrophils after they have produced their NETS
They die :(
Where have large quantities of NETs been found in the body?
found in purulent GCF exudate in periodontitis
What does PAD stand for in PAD4?
Protein arginine deiminase
Which process does PAD4 have an important role in?
Netosis
How does PAD4 aid NETosis?
The arginine in PAD4 makes a key change to the histone proteins that hold our DNA together
arginine amino acids are altered to citrulline in the DNA sequence
This changes the electrostatic charge of the molecule causes the DNA to condense
Why does the alteration of arginine into citrulline have a significant effect on our cells?
As arginine is positively charged and citrulline is neutral
This change in electrostatic charge means that DNA condenses
Name some chemical mediators of inflammation
- Vasoactive amines
- Arachidonic metabolites
- Cytokines and chemokines;
- Lysosomal enzymes;
- Nitric oxide
- Reactive oxygen species
- Compliment proteins
- Coagulation proteins
- Kinins
Give examples of Vasoactive amines
histamine / seratonin
How do Vasoactive amines like histamine regulate the inflammatory response?
They cause:
Vasodilation and vascular permeability
Give examples of Arachidonic metabolites
prostagladins / leukotrienes
How do Arachidonic metabolites like prostagladins regulate the inflammatory response?
They cause:
Vascular reactions
Chemotaxis
Give examples of Cytokines and chemokines;
TNF
IL-1
IL-6
CXCL8
How do Cytokines and chemokines like TNF regulate the inflammatory response?
They lead to:
Leukocyte recruitment
endothelial activation