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Module 7 > Skin & Immune Mediated Disease 2 > Flashcards

Skin & Immune Mediated Disease 2 Flashcards

1
Q

what are the cells and effector mechanisms in innate immunity

A

cells: sentinel cells –> macrophages, mast cells, dendritic cells

effector mechanims: inflammation, complement activation

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2
Q

what are the important cells and effector mechanisms

A

cells: antigen presenting cells: dendritic cells, macrophages

effector mechanism: antibody-mediated (humoral immunity), cell-mediated, immunological memory

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3
Q

how are innate and adaptive immunity linked

A

pathogens can be phagocytosed via primitive “non-specific” mechanisms

mononuclear phagocytes (monocyte/macrophages) can process antigen and “present” it to the immune system (ex. antigen presentation)

antigen presentation triggers the activation and expansion of –> 1. B cells producing antibody specific for the antigen 2. cytotoxic T cells are able to lyse cells infected with the pathogen

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4
Q

what are the 2 key attributes that adaptive (acquired) immunity develops in response to antigens present on invading organisms

A
  1. specificity
  2. memory
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5
Q

what are the skin immune systems

A
  1. physicochemical barriers (stratum corneum, surface lipids, antimicrobial peptides –> defensins, cathelicidins)
  2. skin microbiome (the commensal microorganisms in the skin, have an anti-inflammatory role, affect T cell maturation –> educate T cells, priming them to respond to similarly marked pathogenic cousins)
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6
Q

how does the cornified envelope form

A

loricrin (80%), involucrin

filaggrin breaks down to amino acids (natural moisturizing factor)

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7
Q

how does the lipid bilayer form

A

forms lipids –> extruded from lamellar bodies

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8
Q

what rivets the corneocytes together

A

corneodesmosomes –> structural integrity

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9
Q

what does filaggrin form from

A

profilagrin (keratohyalin granules) –> causes keratins to aggregate

lipids for in lamellar bodies

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10
Q

what % of healthy stratum contains lipid

A

85% lipid

sphingolipids (ceramide)

cholesterol

free fatty acids

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11
Q

what do sphingolipids and fatty acids contribute to

A
  1. physical barrier
  2. permeability barrier
  3. immunologic barrier
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12
Q

which cutaneous lipids have antimicrobial properties

A

sphingoid bases derived from epithelial sphingolipids

mechanisms are not fully understood

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13
Q

what produces antimicrobial peptides

A

ex. defensins, cathelicidins

produced by neutrophils, macrophages, epithelial cells and by bacteria

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14
Q

what is the function of antimicrobial peptides

A
  1. activate and recruit inflammatory cells
  2. alarm and arm keratinocytes
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15
Q

what is the skin microbiome

A

the skin like the gut needs microbial signals and proper immune function

commensal microbes (ex. staph epidermidis) stimulate skin and immune cells to produce IL-1

IL-1 activates T cells which become more responsive to invading organisms

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16
Q

what are the factors affecting skin microbiome

A
  1. host physiology (sex, age, site)
  2. environment (climate, geographical location)
  3. immune system (previous exposures, inflammation)
  4. host genotype (susceptibility genes such as filaggrin)
  5. lifestyle (occupation, hygiene)
  6. pathobiology (underlying conditions such as diabetes)
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17
Q

what is the role of commensal bacteria (microbiome) in innate immunity

A
  1. facrtors produced by commensal bacteria modulate the skin immune system
  2. staphylococcus epidermidis produces –> antimicrobial peptides, small molecules which enhance expression of defensins
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18
Q

what are the cells of the skin immune system

A
  1. keratinocytes (squames)
  2. dendtritic cells
  3. mast cells
  4. lymphocytes (T cells)
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19
Q

what are the functions of keratinocytes (squames)

A

account for the majority of epidermal cells

mitosis of stem cells in s. basale

important in keratin production

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20
Q

what are the function of dendritic cells

A

major role in antigen presentation

epidermal (Langerhan cells)

dermal

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21
Q

what are the functions of mast cells

A

release histamine

22
Q

what are the function of lymphocytes (T cells)

A

various T-helper subsets

23
Q

what are chemokines and cytokines

A

chemokines: critical in T cell and macrophage recruitment
cytokines: arm effectors and direct the immune response

24
Q

what are the roles for keratinocyte

A
  1. sentinel cell activate in host defence –> express pattern recognition receptors (PRRs) respond to DAMPs and PAMPs (associated with microbial invasion)
  2. pro-inflammatory effector cell –> reacts to harmful insult –> producing a complex mixture of AMPs, pro-inflammatory cytokines and chemokines
  3. non-proffessional antigen-presenting cell –> expresses MHC class II molecules can interact with antigen-experienced T cells
25
Q

what is the innate immune response to injury or pathogen invasion

A
  1. release of primary cytokines –> inflammation –> upregulation of endothelial expression of adhesion molecules –> recruitment of additional innate effector cells
  2. activation of skin cells and resident innate immune cells –> langerhan’s cells & dermal dendritic cells carry antigen to draining lymph node
26
Q

what are the adaptive immune response in the skin

A
  1. memory T cell carry TCRs specific for antigen previously encountered in skin
  2. interaction of antigen specific T cells with APCs results in T cell activation
  3. cytokines stimulate expression of T cell specific chemokine ligands on endothelium
  4. T cells recruited by antigen non-specific mechanism
27
Q

what are langerhans cells and what is their function

A

epidermal dendritic cells

dendritic cells link the innate and adaptive immune responses

langerhans cells interact with skin resident memory T cells

28
Q

what is the response of the epidermis to injury

A

release of pro-inflammatory cytokines & growth factors by keratinocytes

–> altered proliferation & differention (hyperplasia, hyperkeratosis/parakeratosis)

29
Q

what is the response of the dermis to injury

A

stimulation of dermal inflammation (erythema, inflammatory edema, exudation)

–> release of secondary cytokines/growth factors promotes further change –> antigen presenting cells interact with T cells

30
Q

what is the are epidermal responses to injury (7)

A
  1. orthokeratotic hyperkeratosis
  2. parakeratotic hyperkeratosis
  3. hypergranulosis
  4. acanthosis
  5. hyperplasia
  6. hyper- or hypopigmentation
  7. lichenification
31
Q

what is orthokeratotic hyperkeratosis

A

increase in thickness of anuclear surface keratin

32
Q

what is this

A

orthokeratotic hyperkeratosis

increase in thickness of anuclear surface keratin

33
Q

what is this

A

parakeratotic hyperkeratosis

thickened keratin layer has retained nuclei

34
Q

what is this

A

hypergranulosis

prominent granular layer associated with hyperkeratosis

35
Q

what is this

A

acanthosis

broadening of the spinous (prickle cell) layer –> often accompanies hyperplasia

36
Q

what is this

A

hyperplasia

an increase in the number of cells often irregular

37
Q

what is this

A

altered pigmentation

pigmentary incontinence

38
Q

what is this

A

lichenification

hyperkeratosis, hyperplasia and dysplasia

39
Q

what are examples of direct traumatic skin disease

A
  1. friction/pressure
  2. chemical (irritant contact dermatitis)
  3. heat (burns)
  4. light (phototoxicity)
40
Q

what are the indirect causes of traumatic skin disease

A

metabolic (photosensitivity)

41
Q

what is self trauma

A

major contributing factor in the development and progression of skin disease in animals

42
Q

what is self-trauma a response to (2)

A
  1. response to pruritus (or pain)

–> action of various mediators, epidermal & dermal sensory nerves

  1. scratch reflex –> spinal reflex, modulated by motor cortex neurons
43
Q

what is the itch-scratch cycle

A
44
Q

what is hairless plaques (acral lick dermatitis)

A

self trauma in skin disease

also known as lick granuloma

may reflect underlying pyoderma

may be an indication of behavioural disturbance

45
Q

how do you distinguish orthokeratotic from parakeratotic hyperkeratosis

A

???

46
Q

are antimicrobial peptides good or bad

A

?

47
Q

what is the skin microbiome and how does it help

A

?

48
Q

what is this cell and what is its role in protection of the skin

A
49
Q

is this cell part of the innate or activated immune response

A

?

50
Q

which epidermal changes result in thickening of the skin

A

?

51
Q

which immune cell can be of myeloid or lymphoid origin

A

?

52
Q

what are the differential features of innate and adaptive immunity (self/non-self discrimination, lag phase, specificity, diversity, memory)

A

innate:

self/non-self discrimination: present, reaction is against foreign

lag phase: absent, response is immediate

specificity: limited, the same response is mounted to a wide variety of agents
diversity: limited, hence limited specificity
memory: absent, subsequent exposures to agent generate the same response

adaptive:

self/non-self discrimination: present, reaction is against foreign

lag phase: present, response takes at least a few days

specificity: high, the response is directed only to the agents that initated it
diversity: extensive, and resulting in a wide range of antigen receptors
memory: present, subsequent exposures to the same agent induce amplified responses

Module 7 (50 decks)

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