Chronic Inflammation Flashcards
What is the innate immune system?
Refers to nonspecific defence mechanisms that come into play
What are the 3 possible outcomes of acute inflammation?
- Resolution (ideal)
- Repair
- Chronic inflammation
What is involved in ‘resolution’?
Phagocytosis of insulting agent, fibrinolysis, phagocytosis of debris
Tissue returns to normal state
What is involved in ‘repair’?
Organisation (replacement by granulation tissue) –> fibrous scar (collagen deposition).
Often happens where there is extensive amount of tissue destruction or tissue is not able to regenerate.
What is involved in ‘chronic inflammation’?
Acute inflammation (AI) progresses and turns into chronic.
Organisation (granulation tissue) + macrophages/lymphocytes/plasma cells.
Does AI involve innate or adaptive immunity?
Innate
Does CI involve innate or adaptive immunity?
Innate and adaptive
Timescale of AI compared to CI?
AI - hours/days
CI - weeks/months/years
What is angiogenesis?
New blood vessels form from pre-existing vessels, formed in the earlier stage of vasculogenesis.
What tends to happen to blood vessels in CI?
Angiogenesis and fibrosis (deposition of collagen)
I.e. concomitant tissue destruction and repair
What tends to happen to blood vessels in AI? What does this lead to?
Blood vessel dilatation and increased permeability
This leads to fluid exudation, rich in proteins eg Ig, fibrinogen.
What cells are primarily involved in AI?
Neutrophils, mast cells, macrophages
What cells are primarily involved in CI?
Macrophages, lymphocytes (T and B cells), plasma cells.
Physical features of AI?
Rubor, calor, tumor, dolor.
Physical features of CI?
Amyloidosis. Cachexia. Anaemia of chronic disease.
What is cachexia? What is this thought to be due to?
A “wasting” disorder that causes extreme weight loss and muscle wasting, and can include loss of body fat.
Thought to be due to release of cytokines.
What is amyloidosis? What is it due to?
Deposition of protein fibrils in various organs which can cause dysfunction.
Due to increase in serum amyloid A (produced by liver during infection/inflammation)
What is anaemia of chronic disease / anaemia of inflammation?
Cytokine release can affect bone marrow production of RBCs, leading to anaemia
What does helicobacter pylori cause?
Acute gastritis
What can happen if infection from helicobacter pylori is not cured?
Progresses to chronic inflammation
What are the circumstances under which CI can arise?
- Progression from acute e.g. helicobacter pylori.
- Recurrent episodes of acute e.g. chronic cholecystitis.
- Persistent infection by certain microorganisms (difficult to remove) e.g. TB, leprosy
- Prolonged exposure to potentially toxic agents (endogenous e.g. bone, exogenous e.g. asbestos fibres, sutures).
- Autoimmunity e.g. Hashimoto’s thyroiditis.
- Unknown e.g. Crohn’s disease, ulcerative colitis, sarcoidosis.
How can bone be an endogenous cause of CI?
If bone has splintered off and sits in tissue –> macrophages and cells of CI response will try to phagocytose and remove it (difficult to remove)
What is Hashimoto’s thyroiditis?
CI of thyroid gland
What is chronic pyelonephritis?
Chronic inflammation and infection of the kidney
Can occur due to obstruction of ureter which can lead to stagnant urine in kidney –> infection and inflammation
Inflammation leads to tissue destruction
What is cirrhosis?
Prolonged exposure to toxic agent (hepatitis, alcohol) leads to late stage of scarring (fibrosis) of the liver
CI response leads to tissue destruction, attempts for tissue repair (forms nodules), collagen deposition
Why can prolonged exposure to toxic agents lead to CI?
Toxic agents are difficult to phagocytose –> prolonged immune response
What key components are found in connective tissue cells during CI?
- Mast cells
- Fibroblasts
- Macrophages
Where are mast cells located?
Located in areas below the epithelium in connective tissue surrounding blood cells
What is the function of mast cells during CI?
Produce granules (contain important chemical mediators e.g histamine)
What is the effect of histamine?
Histamine increases the permeability of the capillaries to white blood cells and some proteins, to allow them to engage pathogens in the infected tissues.
Shape of fibroblasts?
Elongated/oval/spindle shaped
Function of fibroblasts in CI?
Synthesises ECM and collagen –> gives rise to fibrous scars