S3) Chronic Inflammation Flashcards

1
Q

What is chronic inflammation?

A
  • Chronic inflammation refers to the prolonged inflammatory response that involves a progressive change in the type of cells present at the site of inflammation
  • It is characterised by the simultaneous destruction and repair of the tissue from the inflammatory process
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2
Q

Why does chronic inflammation occur?

A

Chronic inflammation takes over acute inflammation in a few hours if the injurious agent is not quickly removed (hence, persists)

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3
Q

How does chronic inflammation present?

A

With regards to the four clinical signs of acute inflammation, redness and heat resolve but swelling but pain persists in chronic inflammation

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4
Q

What is the dominant cell in chronic inflammation?

A

The dominant cell in this type of inflammation is the macrophage and the process is more sophisticated than that seen in acute inflammation

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5
Q

What are the possible injurious agents causing chronic inflammation?

A
  • Micro-organism
  • Necrotic tissue
  • Foreign body
  • Crystalline substance
  • Antigen
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6
Q

Draw a comparison between chronic and acute inflammation in terms of the following:

  • Cells involved
  • Chemical mediators involved
  • Lesion formed
  • Clinical examples
A
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7
Q

How can chronic inflammation arise?

A
  • Takes over from acute inflammation (most common)
  • Begins without preceding acute inflammation, e.g. tuberculosis, RA
  • Develops alongside and superimposed on acute inflammation e.g on-going bacterial infection
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8
Q

Describe the microscopic appearance of chronic inflammation

A
  • Macrophages and lymphocytes are present
  • Granulation tissue begins to form
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9
Q

Identify the cells principally involved in chronic inflammation

A
  • Macrophages
  • T and B lymphocytes
  • Eosinophils
  • Fibroblasts
  • Myofibroblasts
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10
Q

In the context of chronic inflammation, what are macrophages?

A

Macrophages are derivatives of blood monocytes and migrate into tissue spaces at the site of inflammation, after neutrophils, to take over from them

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11
Q

What are the functions of macrophages?

A
  • Phagocytosis
  • Antigen presentation
  • Activate other cells (secrete substances)
  • Stimulate angiogenesis
  • Induce fibrosis
  • Induce fever, acute phase reaction and cachexia
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12
Q

In the context of chronic inflammation, what are lymphocytes?

A

Lymphocytes are cells of the immune system which are present in tissues where there is antigenic material

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13
Q

What are the functions of lymphoctes?

A
  • Process antigens
  • Secrete antibodies (B lymphocytes)
  • Secrete cytokines (T lymphocytes)
  • Kill tumour / virus-infected cells (natural killer cells)
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14
Q

What are eosinophils and what do they do?

A

Eosinophils are immune cells which attack large parasites such as worms and they are present in high numbers in some immune responses e.g. in the bronchi in asthma, Hodgkin’s lymphoma

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15
Q

What do fibroblasts do?

A
  • Respond to chemotactic stimuli and move to sites where they are needed
  • Produce connective tissue substances e.g. collagen, elastin and GAGs
  • Differentiate into myofibroblasts (can contract)
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16
Q

What are giant cells?

A

- Giant cells are cells formed when macrophages fuse with each other in circumstances when foreign bodies / certain bacterial infections are present

  • These cells can be very large, contain dozens to hundreds of nuclei and are seen in granulomatous inflammation
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17
Q

What are the three types of giant cell?

A
  • Touton giant cells
  • Langhans giant cells
  • Foreign body giant cells
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18
Q

Describe the structure of Langhans giant cells.

Where are they often seen?

A
  • Nuclei are arranged around the periphery of the giant cell
  • Often seen in tuberculosis (not exclusively)
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19
Q

Describe the structure of foreign body giant cells.

Where are they often seen?

A
  • Nuclei are arranged randomly in the giant cell
  • Often seen when an indigestible foreign body is present (not exclusively)
  • Large foreign bodies stick to cell surface, small foreign bodies are phagocytosed
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20
Q

Describe the structure of touton giant cells.

Where are they often seen?

A
  • Nuclei are arranged in a ring towards the centre of the giant cell
  • Form in lesions where there is a high lipid content e.g. fat necrosis and xanthomas
21
Q

What are possible complications of chronic inflammation?

A
  • Fibrosis and impaired function
  • Involvement in inappropriate immune responses
22
Q

What is the role of collagen production in chronic inflammation?

A
  • Collagen production is initially helpful as it walls off infected areas produces a fibrous scar to replace damaged tissue
  • This is essential in wound healing
23
Q

What is fibrosis and how does it lead to impaired function in chronic inflammation?

A
  • Fibrosis is the excess production of fibrous tissue, occurring when fibroblasts are stimulated by cytokines to produce excess collagen
  • This replaces normal parenchymal tissue and impairs organ function e.g. interstitial fibrosis of the lung
24
Q

Provide six clinical examples of chronic inflammation

A
  • Rheumatoid arthritis
  • Ulcerative colitis
  • Crohn’s disease
  • Chronic cholecystitis
  • Chronic gastritis
  • Cirrhosis
25
Q

What is rheumatoid arthritis?

A
  • Rheumatoid arthritis is a long-term condition that causes pain, swelling and stiffness in the joints
  • The symptoms usually affect the hands, feet and wrists
26
Q

What is ulcerative colitis?

A
  • Ulcerative colitis is a long-term condition, where the colon and rectum become inflamed
  • Small ulcers can develop on the colon’s lining, and can bleed and produce pus
27
Q

What is Crohn’s disease?

A
  • Crohn’s disease is a long-term condition that causes inflammation of the lining of the digestive system
  • Inflammation can affect any part of the digestive system, but most commonly occurs in the ileum / large intestine
28
Q

What is chronic cholecystitis?

A
  • Chronic cholecystitis involves repeated episodes of acute inflammation of the gallbladder
  • It usually occurs when a gallstone blocks the cystic duct
29
Q

What is chronic gastritis?

A
  • Chronic gastritis occurs when the stomach lining becomes inflamed, often due to bacterial infection by Helicobacter pylori
  • It can be painless or cause dull, persistent stomach pain
30
Q

What is an ulcer?

A

An ulcer is breach in the mucosa to the level of submucosal layer/deeper

31
Q

How does Helicobacter pylori cause gastritis?

A

Helicobacter pylori stimulates the production of pro-inflammatory cytokines, directly injures epithelial cells and increases acid secretion

32
Q

What changes can be seen microscopically in chronic gastritis caused by Helicobacter pylori?

A
  • Helicobacter pylori organisms
  • Chronic inflammation (lamina propria, superficial epithelium)
  • Lamina propria fibrosis
  • Mucosal atrophy
  • Intestinal metaplasia
33
Q

Which malignancies are associated with Helicobacter pylori gastritis?

A
  • Gastric adenocarcinoma
  • MALT (mucosa associated lymphoid tissue) lymphoma
34
Q

What is cirrhosis?

A
  • Cirrhosis is the scarring of the liver caused by continuous long-term liver damage
  • Scar tissue replaces healthy tissue irreversibly in the liver and if extensive, impairs liver function (liver failure)
35
Q

What are granulomas and when do they form?

A
  • A granuloma is a mass of granulation tissue, formed in response to infection, inflammation or due to the presence of a foreign substance
  • They wall off substances the body perceives as foreign and unable to eliminate e.g. foreign bodies (thorns), bacteria like Mycobacterium tuberculosis
36
Q

What do granulomas do?

A
  • The granuloma forms around the particle which is free/phagocytosed within its centre
  • It walls the particle off whilst concentrating mononuclear cells within its centre hoping to destroy the particle
37
Q

What is granulomatous inflammation?

A

Granulomatous inflammation is a type of chronic inflammation in which granulomas are seen

38
Q

What do foreign body granulomas do and what do they contain?

A
  • Contain: macrophages, foreign body giant cells, epithelioid cells, some fibroblasts (at periphery), very few lymphocytes
  • Function: develop around non-antigenic material e.g. surgical thread
39
Q

What do hypersensitivity / immune type granulomas do and what do they contain?

A
  • Contain: macrophages, Langhans giant cells, epithelioid cells (more prominent), some fibroblasts (at the periphery), lymphocytes
  • Function: develop around insoluble antigenic particles that cause cell-mediated immunity e.g. in tuberculosis, syphillis
40
Q

Besides TB and syphillis, where else are hypersensitivity granulomas seen?

A
  • Sarcoidosis
  • Wegener’s granulomatosis
  • Crohn’s disease
41
Q

What is a key process occuring in immune type granulomas?

A

Immune type granulomas undergo central necrosis

42
Q

What is sarcoidosis?

A
  • Sarcoidosis is a rare condition of unknown cause which causes granulomas to develop in the organs of the body
  • It usually affects the lungs and skin
43
Q

In 7 steps, describe what happens when a person inhales Mycobacterium tuberculosis

A

⇒ MTB enters macrophages by endocytosis

⇒ MTB replicates within phagosome

⇒ MTB proliferates in alveolar macrophages and air spaces

Bacteraemia develops + seeding of multiple sites

⇒ 3 weeks later, T helper cell response activates macrophages

⇒ Activated macrophages produce TNF

⇒ Monocytes differentiate into epithelioid histiocytes, forming granulomas

Contains illness in many

44
Q

Describe what is meant by the following terms:

  • Mantoux test
  • BCG
A
  • Mantoux test a screening test for tuberculosis
  • -* BCG – a vaccine against tuberculosis that is prepared from a strain of the attenuated (virulence-reduced) live bovine tuberculosis bacillus
45
Q

What is a primary complex?

A

A primary complex consists of local reaction in the lung parenchyma where the organisms lodge and the inflammatory reaction of the associated lymph nodes

46
Q

Describe what is meant by the following terms:

  • Ghon focus
  • Ghon complex
  • Ranke complex
A
  • Ghon focus – a calcified tuberculous granuloma in the lung
  • Ghon complex – a calcified tuberculous granuloma in the lung & hilar lymph node
  • Ranke complex – composed of a ghon focus and an ipsilateral calcified hilar node (seen in healed TB)
47
Q

Describe what is meant by the following terms:

  • Miliary tuberculosis
  • Pott’s disease
  • Scrofula
A
  • Miliary tuberculosis – disseminated tuberculosis throughout the body resulting in tiny lesions seen on a chest X-ray
  • Pott’s disease – TB in the vertebrae
  • Scrofula – TB nodes in cervical region
48
Q

Compare and contrast Ulcerative Colitis and Crohn’s Disease in terms of:

  • Location
  • Pathology
  • Rectum involvement
  • Mucosal inflammation
  • Fistula formation
A