MOD Week 3 chronic inflammation Flashcards
Define chronic inflammation
Chronic response to injury with associated fibrosis
How is chronic inflammation linked to acute inflammation
If damage is irreversible then chronic inflammation may occur to result in repair and scarring. This can also occur through chronic insult, such as autoimmune, hypersensitivity reactions, or chronic infections such as viral hepatitis
What is the difference in cell types visible with chronic and acute inflammation
Chronic inflammation has many macrophages and lymphocytes, whereas acute inflammation is mainly neutrophils.
Describe the role of macrophages in chronic inflammation
They circulate dormant in the blood until activated in an inflammation reaction, where they then travel to the site of inflammation to take over from neutrophils.
Also perform phagocytosis and are antigen presenting, stimulate angiogenesis, induce fibrosis and induce fever, acute phase reaction and cachexia (weakening and wasting of whole body).
What two functions do T lymphocytes have?
Control (CD4+) Cytotoxic function (CD8+)
Is chronic inflammation stereotyped?
No. Heterogeneous.
Where are T lymphocytes released from?
Thymus
What are plasma cells?
Differentiated B lymphocytes with abundant cytoplasm to produce antibodies. Can be told apart by “clock-faced chromatin” down microscope.
Are eosinophils normally seen in the body?
Yes, with larger numbers in chronic inflammation
What are the roles of fibroblasts and myofibroblasts
Making collagen and connective tissue substances including elastin and GAGs
Respond to chemotactic stimuli to move to sites
What does presence of plasma cells in blood samples indicate?
Considerable chronicity (chronic inflammation)
What is a giant cell?
A cell formed when many macrophages fuse together to form a GIANT cell. They have many nuceli due to frustration of macrophages from too much phagocytosis requirement.
The type of giant cell present can help to aid diagnosis
Describe a Langerhans giant cell and when it is most commonly seen
Foamy granular cytoplasm with nuclei at periphery.
Seen in TB
Describe a foreign body giant cell and when it is most commonly seen
Nuclei are random within the cell.
Seen when a foreign body is present which is hard to ingest, so putting stress on macrophages. If the foreign body is small enough then it is ingested. If not, then the foreign body sticks to the cell surface.
Describe a Touton giant cell and when it is most commonly seen
Nuceli are arranged in a ring towards the centre of the cell
Seen in regions of high level fat necrosis and xanthomas. In the blood sample, there will also be foam cells present as macrophages will have phagocytised a lot of lipid.
What are the three times when acute inflammation can occur?
- taking over form acute inflammation
- without preceding acute inflammation (chronic infection or autoimmune condition) DE NOVO
- alongside acute inflammation as an ongoing bacterial infection
What are the possible complications of chronic inflammation?
Fibrosis and impaired function:
- Fibrosis is an excess of fibrous tissue
- Excess collagen produced replaces parenchymal tissue, This impairs organ function.
- If the area contains enough myofibroblasts then the area can contract to cause further problems.
Involvement of inappropriate immune responses:
- Immune system uses inflammation as non-specific weapon
- Can attack innocuous targets, such as pollen
- Can attack normal body tissue in an autoimmune reaction. The resulting chronic inflammation becomes disease.
What is granulomatous inflammation?
Occuring at the same time as healing occurs, when chronic inflammation is accompanied by granulomas.
What is a granuloma?
Aggregation of macrophages , adapted to look like epithelia. This means they are elongated with eosinophillic cytoplasm and are tightly packed together (hence called epithelioid cells). They form around particles which are difficult to digest and get rid of; with some walling around the edge whilst others in the centre destroy the particle.
What are the two types of granuloma?
Foreign body- containing macrophages, foreign body giant cells, epithelioid cells, fibroblasts and a few lymphocytes. They develop around things which are not antigenic e.g. surgical thread.
Hypersensitivity- containing macrophages, langhan giant cells, some fibroblasts at periphery and a few lymphocytes. There is central necrosis observed (for example in TB and leprosy) and they develop around insoluble, antigenic particles, causing cell mediated immunity. This type of granuloma is seen in sarcoidosis, Wegner’s granulomatosis and Crohn’s disease. When a granuloma occupies parenchymal space in an organ it is harmful.
Do the granuloma and type of giant cell have to match?
No!
What are the effects of chronic inflammation?
Fibrosis (cirrhosis) , impaired function (chronic IBS) , atrophy (gastric mucosa), stimulation of immune response (macrophage-lymphocyte interactions)
Describe chronic cholecystitis
Repeated obstruction by gall stones and repeated acute inflammation leads to chronic inflammation and fibrosis of gall bladder wall
Describe gastric ulceration
Ulceration occurs due to imbalance of acid production and mucosal defence.
Acute gastritis is due to alcohol or drugs (such as aspirin)
Chronic gastritis is due to helicobacter pylori infections
