Chronic Inflammation Flashcards
What are the key characteristics of acute inflammation?
- Rapid response to any injury
- Macroscopic: redness, swelling, heat, pain and loss of function
- Microscopic: vascular dilatation, exudate into tissues and neutrophils emigrate
- Controlled by short-term chemical mediators
- Neutrophils
- fast acting
- short-lived phagocytes that engulf & degrade bacteria
- Phagocytosis by enhanced opsonisation
- Oxygen-dependent bacterial killing
- Defects in the system lead to sever susceptibility to infection
What is chronic inflammation?
“Chronic response to injury with associated fibrosis”
- Different timescale to acute response but the same effectors are used
- Overlaps with host immunity
- Heavily associated with fibrosis
What are the two routes to chronic inflammation?
- Acute insult -> Acute inflammation -> Severe damage -> Chronic inflammation
- Chronic insult -> Chronic inflammation
Both result in repair and fibrous scarring.
How does Chronic Inflammation arise?
- May follow from acute inflammation if damage is too severe to be resolved (most common)
- De novo
- from autoimmune conditions e.g. RA
- chronic infections e.g. viral hepatitis
- “chronic low-level irritation”
- Develops alongside acute inflammation e.g. ongoing bacteria infection
- in severe persistent or repeated inflammation
What does chronic inflammation look like?
Characterised microscopically which are much more variable than acute inflammation.
- Macrophages
- Lymphocytes
- Plasma cells
- Eosinophils
- Fibroblasts/ Myofibroblasts
- Giant Cells
- Langhans type giant cells (TB)
- Foreign body type giant cells
- Touton giant cell
What are macrophages?
- phagocytic cells with a bean-shaped nucleus and abundant cytoplasm
- derived from blood monocytes
- become macrophages when in tissue
- in acute and chronic inflammation
What are the functions of macrophages?
- Phagocytosis
- Antigen presentation
- Synthesis of:
- cytokines
- complement components
- blood clotting factors
- proteases
- Control of other cells by cytokine release
- Stimulating angiogenesis
- Inducing fibrosis
- Inducing fever, actue phase reaction and cachexia (wasting of the body)
What are lymphocytes?
- Predominat cells of the immune system
- Characterised into B and T lymphocyte s
- Presence in tissue they are normally absence in indicates that some antigenic material is or has been there
What are the functions of lymphocytes?
- Processing of antigens
- Secreting antibodies (carried out by differentiated B lymphocytes)
- Secreting of cytokines which influence other inflammatory cells
- Killing of cells (through natural killer cells attacking virus infected cells or tumour cells)
What are eosinophil and when are they normally found?
- Cells with a double lobed nucleus with red granules.
- Found scattered throughout the tissues
- Attack large parasites such as worms
- Present in high numbers in some immune responses:
- bronchi of asthmatics
- Hodgkins lymphoma
What are plasma cells and how are they revelant to the immune response?
- Differentiated antibody producing B lymphocytes.
- Confers chronic disease
- Produces imunoglobulins
What are fibroblast and myofibroblasts?
- Fibroblasts are the predifferentiated from of myofibroblasts
- Fibroblasts can response to chemotaxic stimuli and move to where they are needed
- produces collagen, elastin and glucosaminoglycans.
- Myofibroblast have the ability to contract in wound healing
What are giant cells?
- Macrophages fused together to produce larger cells
- caused by foreign bodies or infection with certain bacteria are present
- Large cells with dozens to hundreds of nuclei
- Seen in granulomatous inflammation
What are the three types of giant cell?
- Langhan’s Giant Cells
- Touton Giant Cells
- Foreign Body Giant Cells
Where are Langhans giant cells normally found?
- nuclei are arranged around the periphery of the giant cell
- normally seen in tuberculosis
- the immune system find the TB bacteria difficult to resolve
What do foreign body type giant cells look like and where are they normally found?
- nuclei are arranged randomly in the cell
- often seen when there is a hard to digest foreign body
- if the foreign body is small it can be phagocytosed by the giant cell and seen within it.
- if it is large the foreign body giant cell sticks to its surface
What do touton giant cells look like and where are they normally found?
- nuclei are arranged in a ring towards the centre of the cell
- form in lesions where there is a high lipid content such as fat necrosis and xanthomas
- due to fatty tissue being avascular, large marcophages are required to clean up dead fat tissue
- lesions also contain foam cells
What are the common causes of liver cirrhosis?
- Alcohol
- Infection with HBV and HCV
- Imunnological
- Fatty liver disease
- Drugs and toxins
What is cirrhosis?
Scarring. Caused by chronic inflammation with fibrosis. Structural architecture is distrupted through attempted regneration.
When can chronic inflammation cause increased function?
- Thyrotoxicosis
- Graves’ disease - excessive production of thyroid hormone
- Autoimmune disease characterised by autoantibodies againt thyroid hormone receptor
When can chronic inflammation cause atrophy?
- In the gastric mucosa inflammation reduces the number of cells and their size in a tissue.
What do foreign body granulomas contain?
- non antigenic material e.g. surgical threas
- macrophages
- foreign body giant cells
- epithelioid cells
- periphery fibroblasts
- lymphocytes
What do hypsensitivity or immune type granumlomas contain?
- central casesous necrosis (often seen in TB associated granulomas)
- develop around insoluble but antigenic particles that cause cell mediated immunity
- Contains:
- macrophages
- giant cells
- epithelioid cells
- periphery fibroblasts
- lymphocytes
- Can be harmful if occupying the paenchymal space within an organ
What is tuberculosis?
Respiratory disease cause by mycobacteria (M. tuberculosis):
- bacteria contains wall lipids
- produces no toxins or lytic enzymes
- causes disease by persistance and induction of cell-meidated immunity
What is sarcoidosis?
Disease involving an abnormal collection of inflammatory cells forming granulomas mainly in the lungs, skin or lymph nodes although any organ cen be affected.
- normally found in young adult women
- granulomas are non-caseating with giant cells
