Inflammation

Question 1

1. Name 4 reasons why Inflammation is important?

Answer 1

• Pathogenic basis of many diseases
• Roles in triggering IMMUNITY
• A set of processes that keeps us alive
• Most AI drugs work by preventing formations/actions of mediators
• Works on a daily basis
• Deficiency in a segment of inflammation can cause severe diseases
• Complex relationship inflammation / cancer
• Dysregulation of inflammation: lethal/chronic, debilitating diseases

Question 2

2. What are the three main causes of acute inflammation?

Answer 2

Injury, Infection or Foreign Body

Question 3

3. Define INFLAMMATION

Answer 3

the reaction of vascularised living tissues to local injury or infection, characterised by the movement of fluid & leukocytes from the blood into the affected tissue.

Question 4

4. Describe the Formation and Components of Pus

Answer 4

• Essentially DNA & debris.
• Bacteria remnants in interstitial fluid as a result of killing; constitutes dead & dying microorganisms
• Leukocytes also undergo apoptosis and die; their remnants in pus (neutrophils, e.g.)
• Enzyme accumulates in the pus that gives it the yellow colour, e.g. myeloperoxidase from neutrophils
• Dead & damaged tissue
• Plasma proteins due to ‘leakiness’ of vessel; antibody, complement system products, fibrinogen, fibrin

Question 5

5. Where are leucocytes produced?
   a) Spleen
   b) Lymph nodes
   c) Bone marrow
   d) Liver
   e) All of the above

Answer 5

c) Bone marrow.

It is signalled to produce more leucocytes when required.

The spleen is a store of leucocytes; they accumulate in the body in inflammatory periods, but destroyed when no longer needed to normal homeostatic levels of WBCs

Question 6

6. Monocytes undergo a maturation process stimulated by chemical signs, after which it turns into a…
   a) macrophage
   b) basophil
   c) granulocyte
   d) remains a monocyte

Answer 6

a) macrophage.

The ‘garbage collectors’ of the body, removing bacterial remnants by phagocytotic processes. They are very motile, and actively search for debris.

Question 7

7. What subtype of leucocyte are the following:
   a) V large nucleus, several small nucleoli, v small cytoplasm, granular, rare
   b) Large nucleus, squashed out cytoplasm, motile, so sometimes oddly shaped
   c) V large nucleus relative to cytoplasmic ratio; 80-90% of the cell
   d) unusual looking nuclei; multipolar/polylobular or ‘fragmented’ appearance
   e) unusual looking nuclei, very granular, pink-ish

Answer 7

a) Basophil
b) Monocyte
c) Lymphocyte
d) Neutrophil
e) Eosinophil

Question 8

8. How do lymphocytes differ in their origin to the group including basophils, neutrophils, eosinophils, monocytes and macrophages?

Answer 8

In Haematopoiesis, all of these cells begin from a Multipotential haematopoietic stem cell (Haemocytoblast). This will differentiate into either a Common Myeloid Progenitor or a Common Lymphoid Progenitor cell.

Myeloid-type differentiate into cells including Erythrocytes, Mast and Myeloblast. The latter further differentiates into the leucocytes listed: basophils, neutrophils, eosinophils & monocytes. Monocytes can even further develop into macrophages.

Lymphoid-type differ into Natural Killer cells, or Small Lymphocytes. These differ into B/T lymphocytes.

Question 9

9. Briefly describe the following routes of dissemination:

a) airways
b) lymphatics
c) venules

Answer 9

a) via external environment, lung & airways or gut
b) via circulation -> right heart -> lung (miliary TB)
c) via left heart -> other organs (miliary TB)

Question 10

10. Which is not a symptom of injury leading to acute inflammation?

a) local swelling
b) local pain
c) red streaks away from local region
d) neutrophilia
e) none of the above

Answer 10

e) none of the above; all were symptoms of acute injury.

NB (c): red streaks away from the site of injury e.g. an infected cut is inflammation of the lymph vessels.

Question 11

11. Inflammation does NOT involve (could be more than one):

a) Destruction of microbes
b) Destruction of host cells
c) Anti-coagulation
d) A set of go & no-go signals (stimulatory/inhibitory)
e) A few specific cell types only
f) Complex cell-cell interactions

Answer 11

c) Inflammation involves coagulation
e) Involves numerous cells, mediators etc; not simply limited to a few types…

Inflammation is v physiological; triggers coagulation cascades/events…

Question 12

12. What are the 4 main elements of the body’s defence against microorganisms?

Answer 12

1. BARRIERS: Outer covering of body - skin & mucous membranes (e.g. mouth, GIT), and secretions (mucous, tears).
2. “INNATE IMMUNITY”: Inflammatory phagocytes (neutrophils & macrophages) plus plasma proteins (e.g. complement system), and Natural Killer (NK) cells.
3. LYMPHATIC SYSTEM: Drainage to lymph nodes - more phagocytes encountered.
4. “ACQUIRED IMMUNITY”: (aka ‘adaptive’) - humoral (Ab-mediated) and cellular (leucocyte-mediated) immunity.

Question 13

13. Regarding Thrombosis,

i. Activation of thrombin, formation of fibrin
ii. Release of thromboxane A2 & ADP from platelets
iii. Injury exposes collagen
iv. Blood platelets attach to collagen, forming Initial Haemostatic Plug
v. Aggregation of platelets, deposition of thrombin & stabilisation of initial plug to form “thrombus”

Which outlines the correct order of the above?

a) v, iii, i, ii, iv
b) iii, ii, v, i, iv
c) iii, iv, v, ii, i
d) v, iii, iv, ii, i
e) none of the above

Answer 13

e) none of the above
(d) was the closest, however v. should occur last rather than first.

The correct order of Thrombus formation:

1. Injury exposes collagen
2. Blood platelets attach to collagen, forming Initial Haemostatic Plug
3. Release of thromboxane A2 & ADP from platelets
4. Activation of thrombin, formation of fibrin
5. Aggregation of platelets, deposition of thrombin & stabilisation of initial plug to form “thrombus”.

Question 14

14. True or false?

a) Strong relationship between Inflammation Coagulation
b) Strong relationship between Inflammation Pain
c) Strong relationship between Inflammation Infection

Answer 14

a) True! Macrophages release important modulators of coagulation.
b) True! There exists an important relationship between mechanisms which cause pain in inflammation, and the mechanisms by which we FEEL pain.
c) FALSE. Whilst a role of the inflammatory response can be to localise and eliminate microorganisms, inflammation also exists against elements like damaged cells, inanimate foreign particles, or antigens.

Question 15

15. Which of the following is a correct difference between the two major classes of inflammation?

a) Chronic - a rapid onset
b) Acute - will always be the same cascade of events
c) Chronic - characterised by movement of fluid & neutrophils out of the blood & into the affected tissue
d) Acute - many macrophages & lymphocytes

Answer 15

b) Acute - will always be the same cascade of events; ‘stereotypic’ response to injury/infection. Acute inflammations always start very quickly, but do not last for very long.

(a) & (c) describe acute inflammation.
(d) describes chronic inflammation (granulomatous)

Question 16

16. Sarah is suspected to have acute appendicitis; a specimen is observed down the microscope. What typical features in the tissue does Dr. Steve visualise?

Answer 16

• neutrophils marginating in blood vessel
• spaces filled with oedema fluid
• muscle bundles pushed apart by fluid (oedema) (can characterise smooth muscle cells as long & elongated w flat nuclei)
• infiltrating neutrophils (high number, and in places they shouldn’t be)

Question 17

17. What is diapedesis?

a) firm adhesion of leucocytes to endothelial walls
b) continuous destruction & repair of normal tissue
c) a delayed, prolonged response to injury or infection
d) the passage of blood cells through the intact walls of the capillaries, typically accompanying inflammation

Answer 17

d) the passage of blood cells through the intact walls of the capillaries, typically accompanying inflammation

Leucocyte-endothelial interactions are a multi-step process. “Transendothelial Migrations” involve at some point, circulating leucocytes slowing down and “rolling” on the surface of endothelial cells, as some adhesion molecules will be present in high concentrations. They will infiltrate into the tissue and contribute to inflammation. The main steps:

1. Activation
2. Rolling
3. Firm adhesion
4. Diapedesis in response to tissue-derived chemoattractants

NB: (a) describes step 3 in the above process (preceeding diapedesis), (b) & (c) describe chronic inflammation

Question 18

18. What particular feature of leucocytes can be used to detect the type of inflammation?

a) nucleus
b) granules
c) cytoplasmic processes
d) all of the above

Answer 18

a) nucleus

Acute = mostly polynuclear
Chronic = mostly mononuclear (e.g. macrophages; excluding polynucleated giant cells as they are derived from macrophages)

Question 19

19. Inflammation is important in biomedical science. What are its positive roles in promoting host survival?

Answer 19

• Direct role in host defence against microorganisms
• Role in initiating adaptive immune response
• Role in initiating tissue healing mechanisms

Question 20

20. Inflammation is important in biomedical science. What are examples of its deleterious effects on host survival (complications of inflammation)?

Answer 20

Acute:

• appendicitis (possibility of perforation; can lead to septic shock)
• meningitis (intra-cranial pressure; compression of brain stem can lead to interference or respiratory centre)

Chronic:

• tuberculosis (impairment of lung function)
• arthritis (incapacitation)
• initiation of cancer (maybe! under research)

Question 21

21. What major cell types involved in inflammation are correctly described by the following?

i. kill microorganisms.
ii. regulate movement of protein from blood into tissues. express adhesion molecules.
iii. degrade fibrin & debris. kill micro-organisms. secrete regulatory molecules called ‘cytokines’.
iv. secrete collagen

a) i. macrophages, iv. fibroblasts
b) i. fibroblasts, iii. macrophages
c) i. neutrophils, iv. endothelial cells
d) i. neutrophils, ii. endothelial cells

Answer 21

d) i. neutrophils, ii. endothelial cells

iii. macrophages
iv. fibroblasts

Question 22

22. What are the Vasoactive Mediators of Inflammation and their sources?

Answer 22

1. Amines: histamine - from mast cells, platelets
2. Lipid-derived mediators: prostanoids, leukotrienes - from leucocytes, parenchyma
3. Plasma-derived mediators: complement fragments C3a and C5a (the “anaphylatoxins”), kinins 0 from plasma protein precursors

In terms of Vasodilation (arterioles): Histamine, kinins, prostaglandin E2 and I2.
Re Increased Vascular Permeability (post-capillary venules): Histamine, kinins, C3a, C5a, and leukotrienes B4 and C4.

Question 23

23. What are the Cardinal Signs of Inflammation and their general physiological causes?

Answer 23

• Redness (Rubor) - Vasodilation
• Heat (Calor) - Vasodilation
• Swelling (Tumor) - Increased vascular permeability & increased granulation tissue; mvmt of water (from plasma)
• Pain (Dolor) - Physical & chemical stimulation of nociceptors; nerve endings become sensitised
• also: loss/alteration of function of the given organ/region holding the inflammatory process; resulting from the changes of inflammation (Functio laesa) - causes: pain, reflex muscle inhibition, disruption of tissue structure, fibroplasia (transformation/replacement of tissue into something fibrotic that won’t work anymore) & metaplasia

Question 24

25. What is hyperaemia and how does it contribute to acute inflammation?

Answer 24

An increase in the amount of blood flowing through an area of tissue.
“Heat” and “redness” are consequences of hyperaemia.

It results from:

• VASODILATION of the pre-capillary arterioles
• OPENING of new microvascular beds to the passage of blood (under normal conditions, these capillaries are dormant)

This contributes to the increased blood flow locally.

Question 25

26. How does EXUDATION contribute to swelling? How does TRANSUDATION relate?

Answer 25

Initial stages of inflammation always involve mvmt of water from blood vessel to interstitium; first TRANSUDATION: the protein-poor transport of water. (as opposed to exudation - protein-rich transport). Increasing fluid movement leads to slowing of the blood flow in the affected area; the vessels appear 'congested'; a 'traffic jam' in the microcirculation. Swelling results, endothelial cells become further modified in their physiology; permeability will INCREASE, and lead to EXUDATION: protein-rich transport of fluid into interstitium (salts, plasma proteins, marginating/emigrating neutrophils). Fluid-filled spaces will arise in the tissue; oedema.

Question 26

27. How does exudation occur at the cellular level?

Answer 26

Contraction of endothelial cells create inter-endothelial gaps in post-capillary venules only. (mild acute infl.) In more severe infl: Resulting from DAMAGE to endothelial cells in all micro-vessels.

Question 27

28. True or false: The increase in permeability as a result of inflammation (increased hydrostatic pressure) can occur in any vessel supplying the inflamed tissue/region.

Answer 27

False! The increase in permeability is limited to POST-CAPILLARY VENULES.

Question 28

29. Why is exudation helpful at the beginning of an inflammatory cascade? a) Excess fluid in interstitium dilutes toxins from foreign particles/microbes b) Excess fluid increases flow into lymphatics c) Plasma proteins can infiltrate the interstitium d) Neutrophils may emigrate and assist in the destruction of microorganisms e) all of the above f) none of the above

Answer 28

e) all of the above Re (c), helpful plasma proteins include antibody, complement system components, and fibrin system components.

Question 29

30. What are the functions of histamine (amine mediator) in inflammation? a) Activation leads to arichidonic acid and in turn prostanoids & leukotrienes which are vasoactive mediators b) From mast cells & platelets, activates vasodilation (all microvessels, but primary action on arterioles) c) increased vascular permeability (post-cap venules only) d) b & c e) all of the above

Answer 29

d) b & c NB, number of clinical anti-histaminic drugs, but have little anti-inflammatory effect. (a) refers to LIPID-DERIVED MEDIATORS. NB, interference with arachidonic acid metabolism by non-steroidal anti-inflammatory drugs can reduce/inhibit inflammation.

Question 30

31. How do neutrophils achieve moving out of the circulation to target microbes?

Answer 30

A major role of neutrophils in inflammation is to kill microorganisms, particularly bacteria. In order to go and kills those microorganisms, neutrophils need to move - i.e. from where they normally circulate in the blood - they do this through the use of chemotactins, chemoattractant substances that attract other neutrophils & macrophages.

Question 31

32. Which of the following regarding kinetics of neutrophil production and loss in humans is false? a) Neutrophils are produced at ~1.5 million cells per second b) Neutrophils spend about 12 hours in blood & up to 24 hours in tissues c) Neutrophils only enter tissues when signalled to do so, e.g. in inflammation d) Once in the target tissue and under directed signalling, they can proliferate to increase their number & anti-microbial effects e) none of the above are false

Answer 31

d) is false. Neutrophils are terminally differentiated cells, and CANNOT PROLIFERATE under any circumstances.

Question 32

33. What action is missing from the following neutrophil events in acute inflammation? 1. Margination in small vessels 2. Emigration from vessel into tissue 3. Phagocytosis of micro-organisms 4. Killing of micro-organisms 5. Death of neutrophil

Answer 32

Between events 2 & 3, neutrophils will exhibit chemotaxin release & chemotactic response.

Question 33

34. Margination of neutrophils... a) involves circulating neutrophils coming in contact with the vessel wall and rolling/adhering to the endothelium b) is induced by vasoactive mediators and cytokines, acting on the endothelium initially c) causes congested vessels d) a & b e) a & c

Answer 33

d) a & b

Question 34

35. Discuss the mediators in neutrophil adherence to endothelium.

Answer 34

Specific types of molecules control the specific steps of events. Stage 1: "activation" Stage 2: "rolling" - mediated by proteins called SELECTINS, newly expressed on the endothelium Stage 3: "adhesion" - mediated by INTEGRIN proteins, constitutively (always) expressed Stage 4: "emigration" - also mediated by INTEGRINS

Question 35

36. What are the differences between direct acting and indirect acting chemotactic factors for neutrophils? a) "Direct" agents act on the neutrophils b) "Indirect agents act on other cells (e.g. macrophages) to induce release of chemotaxins (e.g. interleukin-8) c) Direct acting factors include Leukotrienes, Interleukin-8 & formylated peptides d) all of the above e) none of the above

Answer 35

d) all of the above Also, Indirect acting factors include Tumour necrosis factor (TNF), Interleukin-1 and lipopolysaccharide (LPS). I-8, I-1 and TNF are "cytokines" LPS; aka "endotoxin"; produced by some bacteria. Formylated peptides (direct acting) are exclusively prokaryotic products

Question 36

37. Which of the following are CORRECT regarding structural & biochemical properties of neutrophils? (could be more than 1) a) singular-lobed nucleus b) two types of cytoplasmic granule c) no endoplasmic reticulum but prominent golgi apparatus d) multiple mitochondria e) protein synthesis capacity impaired f) energy from aerobic glycolysis (glycogen)

Answer 36

CORRECT: b) two types of cytoplasmic granule e) protein synthesis capacity impaired INCORRECT: a) MULTI-lobed nucleus c) no endoplasmic reticulum OR golgi apparatus d) VERY FEW mitochondria f) energy from ANaerobic glycolysis (glycogen)

Question 37

38. How do neutrophils still serve to kill bacteria after they die? a) release neutrophil extracellular traps made up of DNA strands with anti-microbial proteins attached b) donate phagolysosomes and cytosolic granules to neighbouring neutrophils c) implode as a final oxidative burst against nearby microbes d) none of the above; they do not assist in killing of microorganisms after death

Answer 37

a) release neutrophil extracellular traps (NETs) made up of DNA strands with anti-microbial proteins attached. b & c are false. After death, a neutrophil's nucleus breaks down, and its granule proteins adhere to DNA strands. When the neutrophil lyses, these NETs are released to further combat MO's.

Question 38

39. How are innate immune cells activated?

Answer 38

Recognition of pathogens, i.e. identification of "non-self": evolutionarily conserved microbial components/products = "PATHOGEN-ASSOCIATED MOLECULAR PATTERNS" (PAMPs). Also, through co-evolution of pattern recognition receptors (PRRs): an interface bw the microbial world & immune system.

Question 39

40. How is STERILE inflammation mediated | (as opposed to recognition of foreign substances; microbes)?

Answer 39

DAMMAGE-ASSOCIATED molecular patterns (DAMPs) are released from damaged cells/tissues and these act through PRRs, like PAMPs do, to initiate inflammation. E.g. ATP, RNA, DNA.

Question 40

41. Which of the following descriptions matches Regeneration, Repair and Healing respectively? i. replacement of injured tissue by parenchymal cells of the same type ii. replacement of injured tissue by fibrous tissue iii. regeneration, repair, or some combination of the two a) ii. i. iii. b) i. ii. iii. c) ii. iii. i. d) i. iii. ii.

Answer 40

b) i. ii. iii. REGENERATION: i. replacement of injured tissue by parenchymal cells of the same type REPAIR: ii. replacement of injured tissue by fibrous tissue HEALING: iii. regeneration, repair, or some combination of the two

Question 41

42. REPAIR by fibrosis involves granulation tissue. It begins with the digestion of debris by macrophages, starting within 24-48 hours. What steps follow?

Answer 41

- Proliferation of fibroblasts & ingrowth of new microvessels, starting around 48 hours. (vessels are essential to provide nutrients for fibroblasts to synthesise collagen) - Fibroblasts migrate into margins of wound. - Fibrosis (fibrous tissue production by fibroblasts - main component is collagen).

Question 42

43. Which of the following is incorrect regarding Liable, Stable & Proliferative cells? a) Permanent cells never proliferate b) Stable cells do not normally proliferate but capable of doing so when required c) Liable cells normally proliferate to replace cells that are continually being lost d) Examples of stable cells include fibroblasts, endothelial cells & hepatocytes

Answer 42

a) Permanent cells RARELY proliferate, but not 'never'. Examples include CNS neurons & cardiac monocytes. Examples of Liable cells include gut epithelium & bone marrow stem cells.

Question 43

44. Which of the following is NOT a stage of healing? a) Remodelling b) Proliferation c) Degranulation d) Haemostasis e) Inflammation

Answer 43

c) Degranulation - this is probably something individual cells do... e.g. to counter microbes Otherwise, the FOUR stages of healing, in order, include: 1. Haemostasis - stopping the bleeding 2. Inflammation 3. Proliferation - granulation tissue (soft callus), scar (fibrosis; hard callus) 4. Remodelling - Contraction; scar maturation / wound strength

Question 44

45. What are the differences between healing by first and second intention?

Answer 44

By first intention: incisional wound; implies cut is very small & superficial. Margins can attach, margins are sutured, no infection. By second intention: not a direct repair; will have the formation of important granulation tissue. Open, often deeper wound; margins not ready to attach. Infection often. Margins are devitalised: bruised/necrotic. Larger scar.

Question 45

46. Why is angiogenesis required in Phase 3 of healing?

Answer 45

Phase 3 = Proliferation. Angiogenesis is necessary to support a wound environment that can repair injury. Stimulated by: - macrophage-derived growth factors - hypoxia, fibronectin & hyaluronic acid (found in wound matrix) Supplies oxygen & nutrients for fibroblast proliferation & production of wound matrix

Question 46

47. Describe the process of EPITHELIALISATION in Phase 3: Proliferation, in 2nd Intention Healing.

Answer 46

- Cells in basal layer at wound edge flatten - De-differentiation - Pseudopod formation - Migrate across wound - integrin receptors in underlying extracellular matrix - Cells along margin divide to reform mature, multilayered epithelium - For surgical wounds: complete wound coverage in 24-48 hrs. - Process comprised by bacteria, protein exudate from leaky capillaries & necrotic debris. - Delayed epithelialisation = prolonged & profound inflammatory process - Facilitated by clean moist wound

Question 47

48. What are the cells of granulation tissue and their contributions to its formation?

Answer 47

MACROPHAGES - growth factors Epithelial cells - migrate to the sides of edges Endothelial cells - angiogenesis FIBROBLASTS - ECM formation

Question 48

49. In Remodelling - Wound contraction (2nd wk of healing), a) Myofibroblasts transform into fibroblasts, stimulated by TGF-beta & PDGF. b) Elastin synthesis & degradation is controlled by metalloproteinases. c) Wound gains about 80% strength by 3 weeks. d) A scar is only about 70% of normal skin.

Answer 48

d) A scar is only about 70% of normal skin. INCORRECT: a) FIBROBLASTS transform into MYOFIBROBLASTS (not the other way around), stimulated by TGF-beta & PDGF. b) COLLAGEN (not elastin) synthesis & degradation is controlled by metalloproteinases c) c) Wound gains about 20% (NOT 80%) strength by 3 weeks.

Question 49

50. In Phase 4: Remodelling, contracture of the wound involves... a) Contraction of fibrin b) Myofibroblasts c) Fibroblasts & collagen lattice d) all of the above

Answer 49

d) all of the above

Question 50

51. Which of the following are SYSTEMIC factors affecting healing? (multiple) a) necrosis b) nutrition c) infection d) vitamin deficiency e) age f) foreign body g) mobility h) blood supply i) other diseases j) immune status k) apposition

Answer 50

b) nutrition, d) vitamin deficiency, e) age, j) immune status, i) other diseases. The rest are LOCAL factors affecting Healing (necrosis, infection, apposition, blood supply, mobility, foreign body.)

Question 51

52. True or false? The resistance of wounds to infection is proportional to their blood supply.

Answer 51

True! It is the surgery axiom. Leucocytes deprived of oxygen have an impaired respiratory burst, and will lead to complications of healing.

Question 52

53. Which of the following is NOT a complication of healing? a) Infection b) Foreign bodies c) Metabolic disorders / microvascular problems d) Keloids (hypertrophic scars) e) They are ALL complications of healing

Answer 52

e) They are ALL complications of healing Re. Metabolic disorders / microvascular problems - example is diabetes.

Question 53

54. SUMMARY: INFLAMMATORY PHASE

Answer 53

- Fibrin & Platelet Scab - WCs migrate from capillaries in response to cytokine signals - Dead tissue & debris cleared - More cytokines released

Question 54

55. SUMMARY: PROLIFERATIVE PHASE

Answer 54

- Fibroblasts & endothelial cells enter wound site - Begin to proliferate - Endothelial cells form new blood vessels - Fibroblasts lay down collagen fibres

Question 55

56. SUMMARY: REMODELLING PHASE

Answer 55

- Inflammatory cells & fibroblasts disappear from the scar - Matrix & blood vessel formation shuts down - Collagen is reorganised