Dr. Anderson Inflammation and Repair Page1 of 6

FUN2: 10:00-11:00Scribe: Hunter Neill

Wednesday, November 19, 2008Proof: Taylor Nelson

Dr. AndersonInflammation and RepairPage1 of 6

Abbreviations: WBC = white blood cell

Inflammation and Repair

Introduction and Review: We talked about cell adaptation. You either stress the cell, change your diet, change hormone levels, get pregnant, get cancer, or something happens then the normal milieu changes so you body responds to that change. They respond by:
Hypertrophy
Hyperplasia
Atrophy
Metaplasia
Due to the nature of the stimulus and the nature of the cells that are effected
General way that your body responds to stresses
Who can give me an example of metaplasia
Talked about squamous metaplasia
Lung of a smoker
Renal pelvis of someone with a stone
What is an example of metaplasia that is a different kind than squamous?
Metastasis is neoplasia – new, abnormal growth
Metaplasia is normal adult cells going to another type of normal adult cell
Barretts Esophagus or GERD = Gastro esophageal reflex disease
Acid in your stomach goes up the esophagus and burns the walls – known as acid reflux or heart burn
What kind of cells are lining the esophagus – squamous epithelium
If they we columnar epithelium than chips would rip your esophagus as you swallowed
Its like your skin
What happens when you drop acid on your skin – it hurts
That’s why when you burp acid it hurts in your esophagus
Its stimulated by an abnormal stimulation and goes through metaplasia
If you don’t want to be burned by acid you become more like the stomach
In Barretts esophagus or metaplasia of the distal esophagus the squamous epithelia are replaced by mucous secreting columnar cells
They are just like in the stomach (cuboidal and columnar cells) that secrete a layer of mucous to protect you from that acid
That’s a great thing because it stops the burning however during the process during constant irritation of those with Barretts Esophagus are more likely to develop cancer there.
This is one case where metaplasia is designed to help you so that you don’t burn your esophagus each time your burp, but it also has a negative connotation that over years and years people with gastro esophageal reflex disease may have a higher incidence of cancer in that are as well
You are getting constant irritation. Its cells doing something that their not suppose to be doing and make it likely that a mutation will occur leading to cancer
Cell death – if you cant adapt to a stress the cells die. If they die you end up with necrosis or areas of dead cells. Tissues are dead. Several different types include
Coagulative
Liquafactive
Caseous
If you have dead cells – what is the body going to do? The body isn’t going to give up but rather mount an inflammatory response to either get rid of the insult so you dot end with dead cells. If you do end up with dead cells than clean up the necrosis that has occurred
Today we’re going to talk about inflammation or how the body reacts to things and then if it looses the battle how it repairs the damage after the inflammation
A lot of this has to do with blood cells which are the first reactors (like fireman or policemen)
Once they get out of the tissue – you see the collagen, proteoglycans, fibroblasts, macrophages, resident macrophages (all the tissues have some resident phagocytic cells waiting to do whatever needs to be done to help the body)
Objectives [S2]
5 cardinal signs of inflammation – acute inflammation (fire trucks) and Chronic inflammation (cleaning up the mess) and wound repair (carpenters repairing the house after a flood)
Cell types and the inflammation mediators are involved in the various stages of inflammation
Systemic magnifications of inflammation
Define granuloma and granulomatous inflammation and granulation tissue
Describe the time course of wound healing and the basic mechanisms
Acute Inflammation [S3]
This is the first step in what happens
One hundred years ago acute observations were used. What happens when you twist your skin, etc.
Red (rubor)
Swelling (tumor) - your ankle swells or swells around if you get a cut
Warm (calor)
Tender (dolor) – it hurts and its tender so you have pain
Loss of function (functio laesa) – if you twist your ankle you aren’t going to run a marathon that afternoon
Because of the swelling and pain you loose function in the organ or damaged tissue
One of the most commonly used models is a myocardial infarction – used yesterday with cell injury and again about the inflammatory reaction
Its easy to tie off a coronary artery and kill the animal at 1,2,3,4 hours and look at the heart at each of those time points and look at the histology to see what is occurring
What happens first when you tie off a coronary artery, or block the blood flow to a tissue is edema
The first sign of inflammation is edema, whether it’s a myocardial infarction or an infection or a toxin the body is trying to dilute the noxious stimulus. It produced edema or fluid coming out of the blood stream.
After the fluid comes out neutrophils come out. Whenever you think of acute inflammation think neutrophils
They are the first thing – the first line of defense the first cellular line of defense against any sort of cell injury or noxious stimulus
They can only life a day or two out of the tissue. Once out of the blood they phagocytose things. When they try and phagocytose things they release their enzymes as they sloppily eat. This enzyme activity kills adjacent cells.
Then the macrophages come out. The monocytes in the blood come out of the vasculature and once their out they are called macrophages. Once they are out in the tissue they become activated and phagocytose things and release chemical mediators. (They are like the generals that are controlling everything)
Review: Edema immediately followed by neutrophils (24-30hrs) and then macrophages (48-72hrs). – the neutrophils have died off
Neutrophils [S5]
They are floating in the blood. How do they enter the tissue?
The first thing that happens with inflammation is edema. How do you get edema?
When you have some sort of a noxious stimulus the blood vessel constricts (1ms) and then it dilates. When it dilates, endothelial cells get pulled apart and fluid leaks out between them into the adjacent tissue. That is the edema that you see initially
When the blood vessel capillary and arterioles and the precapillary and venules, when they are doing all this, it causes the blood flow to be abnormal.
If the blood is flowing along perfectly, all the neutrophils are in the center, all the cells are in the center of the column of blood.
Margination - If you dilate the blood get turbulent and the cells start to go to the edges
Adhesion - When they line up along the side of the blood vessel that is called pavementing
Pavement because they stick to the endothelial cells because they have receptors that are complementary to receptors on the endothelial cells
Leukocyte-Endothelial Adhesion diagram [S6] – (straight from the book)
The neutrophils are floating along and turbulence occurs forcing them from the center to the edges
Once they get out to the edges, they have integrin receptors on their surface that bind to selectin receptors on the endothelial cells, which causes them to stick
Because the blood is still moving they then come off and float along and then stick and then float along and then stick to another one – that is called rolling
Mathematically – every once in a while one will bind to two selectins – it slows down for a min and then gets broken loose
Eventually, you will get enough receptors binding that it (the leukocyte) will stop there
Once its stopped, the cells have PCAM receptors on them that cause the cell to migrate in between the endothelial cells that are separated (because the vessel is dilated) and enter the tissue where they meet the toxins and microbes to which they attack and phagocytose.
One of the reasons why the cells come out there because there are chemical signals – chemotactic signals – that are enticing the cells or promoting the cells to crawl through the blood vessel and come out into the extracellular space
[S???] This is a picture of a blood vessel with neutrophils stuck on it. This is a pig that has had an angioplasty. When the endothelial cells were damaged the neutrophils stuck there as part of the rolling ad binding process. Some of them have already crawled through and are in the subcutaneous tissue. Just within an hour, we took this sample and flushed all the blood out leaving behind only the ones that were stuck on tightly. The next image it at slightly higher resolution to show the neutrophils and how they are stuck or partially exiting the blood vessel
Emigration and Chemotaxis Mediators [S7]
One of the reasons why they crawl into the tissue is due to chemotactic factors
Some of the classic chemotactic factors are
Bacterial products – LPS – the molecules on the surface of bacteria attract out neutrophils, which will phagocytose and kill them. The surface proteins – LPS – found on certain bacteria are chemotactic
Complement derivative – C5a – it’s a complement factors in the complement cascade
The C5 component is activated into C5a and C5b and the C5a component is also a good chemoattractant
Arachidonic acid derivatives including leukotriene B4
Cytokines – IL-8
This is the classic list of the classic chemotaxis factors
Chemotaxis happens quickly and works fairly well
[S???(Youtube video)] Here is a human neutrophil in a test tube.
Here is a pipette with picogram quantities of a chemoattractant agent
You can squirt the agent out of the micro pipette and the cell will be stimulated and will start walking toward the pipette
This is what happens if you have bacteria in your tissue
They are coated with chemoattractant
The neutrophils are very mobile and the various thing whether the surface of the bacteria
See how quickly they will move toward the attractant
Emigration and Chemotaxis Defects [S8]
They are some instances where the immigration and chemotaxis doesn’t work very well
WBC defects
Chediak-Higashi Syndrome. This is s syndrome where the WBCs get there okay but when they phagocytose the bacteria or material they cannot kill it. They are defective in their ability to phagocytose and kill things.
Diabetes mellitus – both a chemoattractant defect and a phagocytosis defect
Chemotactic factor defects –
C5 or immunoglobulin deficiency – C5a is a powerful chemoattractant and a deficiency or a deficiency of immunoglobulin in general will result in a poor job of chemoattracting and killing
Serum chemotaxis inhibitors
C5 inactivators – increase in cirrhosis (alcoholics with chronic liver disease or cirrhosis produce molecule that inactivate complement), sarcoidosis, and other diseases
WBC locomotion inhibitors
Chloroquine, cancer and other chronic disease can cause defects defects in the leukocytes ability to move or crawl toward the attractant
All of theses things can lead to problems and people with these sorts of defects are more likely to get chronic infections. Many of these things are diagnosed early in life by the time the child is 2 years old. He might be in the doctors office every month for a new infection and they realize that there must be something going on
Phagocytosis and Degranulation [S9]
Once the leukocyte has migrated and made it to the material it has to phagocytose the material and then kill it
Phagocytosis required 3 distinct steps
Recognition
Attachment
Engulfment and kill it
Recognition and Attachment [S10]
What are some of the things that help it recognize something as foreign and bad?
It’s a process called opsonization and very important clinical issue and in the inflammatory process
Macrophages and neutrophils wander around and try to eat things
If you can wave a red flag that signals to eat this it make the process more efficient
This is what opsonization is – your body makes and immunoglobulin or antibody in response to a bacteria which binds to the bacteria and then on that Ig is the Fc fragment. It is on the tail of the Ig and is complementary to leukocyte receptors. The leukocytes hook onto the Fc receptor and therefore the bacteria and are able to phagocytose the bacteria
Opsonins - things that are good for opsonization are
Fc frament of IgG
C3b – one of the complement components
Mannose-binding protein (receptor produced in the liver)
Cover the surface of microorganisms so that it is easier for neutrophils and macrophages to recognize the bacteria
Diagram of Phagocytosis and Degranulation [S11]
A virus has a mannose (binding protein) or ligand on the surface that binds to the mannose receptor on the phagocyte or neutrophil.
Whether it’s a mannose receptor or Fc receptor that binds to the antibody you get a binding of the noxious agent to the surface of the macrophage
Once its bound, then the macrophage or neutrophil can engulf the material. It must have the locomotion (one of the things that is needed to work well). They move their cytoplasm out around the organism and suck in this vacuole to form a phagosome or cell membrane that has engulfed something and pinched off into the cytoplasm of the cell
This phagosome with the bacteria or virus then fuses with the lysosome (bag full of enzymes) and form a phagolysosome.
Once the phagolysosome is fused the enzymes can attack the organism, successful phagocytosis consists of the enzymes killing the engulfed organism
There are several mechanisms involved in the enzymes: hydrolytic, enzymes that stimulate the production of nitric oxide (oxidizing agent), enzymes that make oxygen free radicals – all of these being important mechanisms by which you kill organisms within the phagolysosome
H2O2 is produced within the phagolysosome via these free radicals
Hypoclorous acid (bleach) is also produced to kill the engulfed organism
Nitric oxide or Oxygen free radicals are very powerful oxidizing agents that oxidize the bacteria
Activation and Destruction (killing)[S13]
Oxygen dependent killing
Primarily myeloperoxidase (enzyme inside the phagolysosome) produces H2O2 and hypoclorous acid
Hydrogen peroxide in conjunction with ferrous ion and the myeloperoxidase can generate the OH free radical which is the really powerful oxidizing agent
The way to think about it and put it all together: the neutrophils come out quickly and phagocytose things, release all their enzymes and die whereas macrophages manage things by secreting multiple chemical mediators
Chemical Mediators of Inflammation [S14]
The way to think about it and put it all together: the neutrophils come out quickly and phagocytose things, release all their enzymes and die whereas macrophages manage things by secreting multiple chemical mediators, they are also capable of phagocytosis but the chemical mediators they secrete manage the process
[S15] Some of the mediators they produce are important for managing the inflammation process
There are basically two types of mediators
The preformed mediators
In vacuoles, released instantly i.e. histamine that is released to produce the brief vasoconstriction seen with an injury
Preformed in secretory granules, the quick stuff
Newly synthesized, released by activated macrophages that do not usually produce these mediators
They must be stimulated to begin producing so it obviously takes a couple of days for the macrophages to get cranked up
The liver is very important for producing clotting factors, complement, and many of the factors that we associate with acute inflammation (acute reactants)
Think about this in terms of people with liver disease – these people will have trouble with blood clotting, inflammation, and are more likely to get sick because they cannot produce enough compliment to opsonize the bacteria
Arachidonic Acid System [S16]
The crux, or chemical mediators of inflammation
The mechanism for the production of all of the leukotrienes, prostaglandins, thomboxane and all of the things that are involved in controlling, managing, and modulating the inflammatory reaction
KNOW that this is the important cascade for producing a lot of the mediators involved in controlling information and you can observe some of the methods of action of common drugs that we use to treat inflammation and
Steroids block phospholipases which is the conversion of phospholipids from cell membrane into the building block for all of the inflammatory mediators (arachidonic acid)
When you take steroids you are virtually stopping the entire cascade
Asprin or indomethacin do not interfere with the production of arachidonic acid and leukotrienes but you inhibit the cyclooxygenases which means you don’t get prostaglandin, thromboxane, prostacyline, etc.
Decrease pain, decreases the vasoconstriction due to thromboxane, decreases the vasodialation caused by prostacycline
TAKE HOME MESSAGE – how you can manage the inflammatory cascade (where you inhibit the cascade with different drugs – steroids, asprin, etc.)
Noninflammatory and Inflammatory Conditions [S17]
With edema – depending upon how far the endothelial cells open up you get just water coming out, or you get small proteins coming out (albumin), or even large proteins coming out depending upon how big the hole is
An intense inflammatory reaction will cause a lot of protein to come out
A minor inflammatory reaction will cause mostly fluid to leak with little protein
[S19] Different types of inflammatory reactions will lead to different exudate:
Serous: Blister, mostly water with a little albumin – example: blister from a slight burn
Fibrinous: More severe inflammation, endothelial cells open a little more (more vasodilation), bigger proteins can get out – fibrinogen comes out with the fluid and once in the tissue fibrinogen gets converted into fibrin leading to fibrinous inflammation – occurs with uremic pericarditis, inflammation in the lungs, sometimes can be idiopathic
Purulent: consist of fluid, protein, and cells (neutrophils) – think pus
Eosinophilic: Full of eosinophils, IgE mediated – seen with asthma patients and parasitic infections
Hemorrhagic: Fluid, proteins, white blood cells, and hemorrhage (red blood cells) – the classic example is rocky mountain spotted fever, rickettsial organisms attacks endothelial cells, killing them and causing the tendency to bleed
Pseudomembranous: Sort of a specific thing with diphtheria being a classic example along with pseudomembraneous entercolitis (people that take broad spectrum antibiotics, kill the natural flora of their GI tract and get an overgrowth of C. difficile, which produces a toxin that kills the cells on surface of GI tract causing them to peel off in one big strip known as a pseudomembrane)
Serous Exudate – Blister [S20]
Photo of serous exudates
Systemic reaction to a drug cased these blisters
Blisters are primarily full of clear fluid with small amounts of albumin
[S21] Histologically it appears clear, because there is hardly any protein present it does not stain
Fibrinous Exudate – Pericarditis [S22]
Photo of a heart with fibrinous exudate (pericardium opened, folded back, and laid over the heart)
Fibrinous, or made up of fibrin
If the kidneys fail and you get high urea nitrogen (BUN) floating around in the blood the surface of the heart is irritated as well as the inner surface of the pericardium – as the heart and pericardium rub against each other it causes and irritation and inflammation which causes fibrin to come out
The red stuff all over the heart looks like clotted blood because fibrin has escaped and been activated to form insoluble fibrin particles that have clumped together causing this appearance
[S23] Histologically, the pericardium is made up of fibrous tissue (bottom of photo) and the sitting on top of that tissue is the fibrinous exudates which stains red under an H and E stain microscopic section – clumps of fibrin (just like a blood clot) that are on top of the heart and on the inner surface of the pericardium, known as fibrinous pericarditis
Acute Inflammation – Purulent [S24]
Photo of purulent exudates in the brain
Acute process
Pus
You get fluid, proteins, and NEUTROPHILS
This is brain of a burn victim who got septic (bacteria floating around in the blood) and got an infection in the meningis of her brain
The white, opaque material under the between the membrane and the brain is due to the purulent inflammation
[S26]Section of the brain with purulent inflammation
Can see blood vessels packed full of blood
Outside of the blood vessels can see many, many neutrophils (little multi-lobed cells), and a few macrophages (just beginning to see the transition from purulent inflammation to a more chronic change where neutrophils are replaced by macrophages)
The pink outside the blood vessels is fibrin
Remember purulent is fluid (edema), proteins (fibrin), and cells (neutrophils)
Pseudomembranous Exudate, Diphtheria [S28]
Photo of trachea affected by diphtheria
Do not see diphtheria much anymore because most are vaccinated, seen periodically in unvaccinated children
Cell that normally line the trachea are affected by C. diphtheria which kills the cells causing an entire layer of dead tissue (pseudomembrane)
[S29]Ring of trachea,columnar epithelia all got infected by diptheria and started dying which stimulated inflammatory response that produced fluid, fibrin, and neutrophils and the air from breathing dehydrated the cells causing the cells to break off in sheets
Can aspirate part of the pseudomembrane, it gets stuck in bronchioles and can cause death by asphyxiation

[End 51 min]