Immunology (Fadock NAVDF notes)

Question 1

Phenotype vs endotype

Answer 1

Endotypes are disease subtypes that are defined by a specific pathophysiological mechanism and biomarkers.

Phenotypes are clinical descriptions of a disease or patient.

Endotypes are important for precision medicine, to prescribe targeted therapies.

Various amounts of Type 2, Type 1, Type 17, and
Type 22 cells and cytokines in atopic dermatitis depending on endotype.

Question 2

Epigenetic definition

Answer 2

How the environmental (pollutants, chemicals, drugs, diet) and behaviorial factors (e.g. stress, anxiety) affect gene expression without changing the sequence of the DNA. These changes are known to be passed from pregnant women to their offspring, affecting prevalence of atopic diseases in the children

Question 3

How does a damaged barrier promote inflammation?

Answer 3

Alarmins from damaged keratinocyte
IL-33, IL-25, TSLP

More allergen penetration to langerhans cells

Question 4

What are epidermal alarmins?

Answer 4

IL-25, IL-33, TSLP

Endogenous molecules that are released by the epidermis in response to tissue damage

Question 5

How do epidermal alarmins promote the Type 2 immune response?

Answer 5

Act on ILC2 cells, which release IL-5 (eosinophils) and IL-13 (Th2 inflammation)

Act on Th2 cells to release IL-4 and IL-13 (Th2 molecules)

Act on Langerhan and dermal dendritic cells

Question 6

What cells are involved in a Type 2 response

Answer 6

*Keratinocytes (alarmins, chemokines, IL-1)
*ILC2 (IL-5, IL-13)
*Th2 (IL-4, IL-13; express CTLA, CCR4, CRTH2)
*DC2 (OX40L)
*B cells (respond to IL-4 to make IgE)
*Eosinophils (express H4R, CRTH2 for prostaglandin binding)

Question 7

What cytokines are involved in a Type 2 response

Answer 7

IL-4
IL-6
IL-13
IL-31

Question 8

Path of an allergen from the skin to the lymph node

Answer 8

Allergen → through keratinocyte layers → Langerhan cell or DC2 processed, presented → Th2 stimulated → DC2 migrates to the LN →trains naive T cells to be Th2 → Th2 stimulates B cells to make IgE → Th2 and B cell go back to skin to release Type 2 cytokines

Question 9

How does the Type 2 response affect the skin barrier?

Answer 9

1) Downregulates ceramide synthesis
2) Downregulates Filaggrin expression
3) Downregulates antimicrobial peptide expression
4) Alters skin protein and lipid content

Question 10

Define the hygiene hypothesis

Answer 10

Lack of microbial exposure in early life may increase the risk of developing allergies

Question 11

How does skin dysbiosis contribute to
allergy?

Answer 11

If more pathogenic Staphylococcus, more superantigen release –> abundant nonspecific T cell signaling (IL-4 production!). Also Basophil activation. Can lead to increased Fas expression and keratinocyte apoptosis –> damage to skin barrier

Superantigens promote Type 2 polarization

Question 12

How does gut dysbiosis contribute to allergy? Is there anything we can do about it?

Answer 12

Western diet
Glycosylation of proteins = more allergenic (from high T cooking!!

The resident microbiota is important in maintaining structural and functional integrity of the gut and in immune system regulation. It is an important driver of host immunity, helps protect against invading enteropathogens, and provides nutritional benefits to the host. Disruption of the microbiota (dysbiosis) may lead to severe health problems.

Yes! Feeding skin barrier fortified diets can improved cAD symptoms

Question 13

How does the environment contribute to atopic dermatitis?

Answer 13

Several environmental inputs: not only allergens, but pollutants,
temperature, changes in humidity, psychosocial factors

Risk factors:
*Pollutants –> ROS via skin, hair follicles, glands.
*Tobacco smoke associated with cAD
*Urban environment = risk factor for cAD
*Climate change? Changes in duration and severity of pollination; temperature and humidity; UV light
*Western, processed diet

Question 14

Role of Aryl hydrocarbon receptor (AHR) in cutaneous hypersensitization

Answer 14

*Transcription factor, activated by pollutants
*KC release artemin when AhR is bound
*Artemin induces hyperinnervation of the epidermis –> dog scratches –> skin barrier damage –> cutaneous hypersensitization

Question 15

How does allergen immunotherapy work? 4 major mechanisms

Answer 15

1) Desensitization of mast cells, basophils, eosinophils (QUICK): increase inhibitory Fc receptors, increase H2 receptors (block action of histamine)
2) Tolerance: generation of Treg, DCreg, IL10+ ILC (ILCreg), Breg, Tfreg; Reduction of Th2 to Th1 ratio
3) Decrease IgE, increase IgG1, IgG2, IgG4, IgA
4) Decreased # mast cells, basophils, eosinophils in tissue

Question 16

Inhibitory cytokines from Tregs

Answer 16

IL-10, TGFb, IL-35

Question 17

What is FoxP3

Answer 17

Transcription factor
Binds DNA to induce expression of Treg development and functional proteins

Question 18

What is atopic-like dermatitis

Answer 18

Failure to identify allergen-specific IgE by intradermal or serum testing

Like “intrinsic” atopic dermatitis in humans

Question 19

Mechanisms of epigenetics

Answer 19

• DNA methylation
• Histone acetylation and methylation
• miRNAs (repress translation)

Question 20

How do ROS affect the skin

Answer 20

• Oxidize lipids in cell membranes
• Activate proteases –> damage skin barrier
• Release proinflammatory mediators from WBC

Question 21

Which topical product binds aryl hydrocarbon receptor?

Answer 21

Tar

Question 22

Which neurotrophic factor does aryl hydrocarbon receptor induce?

Answer 22

Artemin

Question 23

What do Staphylococcus have to promote Type 2 inflammation?

Answer 23

Superantigens (endotoxin)

(Forces MHC cl II on APC and TCR on T cells to bind –> activate nonspecific, robust T cell response!)

Question 24

Cytokines and chemokines released by keratinocytes

Answer 24

IL-1
Alarmins (IL-25, IL-33, TSLP)
Chemokines (TARC/CCL17, MDC/CCL22)

Question 25

TARC/CCL17: Cell that produces it

Answer 25

Keratinocyte

Question 26

TARC/CCL17: cell that responds to it

Answer 26

T cells (Th2, Treg)

Question 27

TARC/CCL17: receptor that binds it

Answer 27

CCR4

Question 28

MDC/CCL22: cell that produces it

Answer 28

Keratinocyte

Question 29

MDC/CCL22: cell that responds to it

Answer 29

Macrophages, DC2

Question 30

MDC/CCL22: receptor that binds it

Answer 30

CCR4

Question 31

Cytokine made by activated B cells

Answer 31

IL-4

Question 32

Cytokines made by activated ILC2

Answer 32

IL-5, IL-13

Question 33

Costimulatory molecule expressed by DC2

Answer 33

OX40L

Question 34

Role of OX40L on DC2

Answer 34

Induce T cells to make IL-4, IL-5, IL-13

Question 35

Which receptor is upregulated by DC2 as they mature, which guides them to the lymph node

Answer 35

CCR7

Question 36

Which cells express CCR7

Answer 36

DC2, T cells, B cells, Treg,

Question 37

CCR7 function

Answer 37

Receptor that binds CCL19, CCL22 Brings lymphocytes, DCs to lymph node

Question 38

Ligands for CCR7

Answer 38

CCL19, CCL22

Question 39

Which receptor on lymphocytes & DCs hones them to the lymph node

Answer 39

CCR7

Question 40

Which cell helps B cells produce IgE

Answer 40

Tfh2 cells via IL-4 Th2 also help

Question 41

Which cytokine helps B cells produce IgE

Answer 41

IL-4

Question 42

Which cytokines are produced by Type 2 CD8+ cells

Answer 42

IFNgamma IL-4 IL-6 IL-13 IL-31

Question 43

Which cytokines are produced by cutaneous Type 2 T cells and B cells

Answer 43

IL-4 IL-6 IL-13 IL-31

Question 44

Which receptors do T cells have to hone them to the skin

Answer 44

1) CLA (cutaneous lymphocyte antigen) 2) CCR4 (binds TARC/MDC) 3) PgD2R2/CRTH2 (binds prostaglandin D2 for chemotaxis)

Question 45

Which receptors do eosinophils express?

Answer 45

1) PgD2R2/CRTH2 (binds prostaglandin D2 for chemotaxis) 2) H4R

Question 46

Which cytokine is implicated in inducing epidermal hyperplasia in more chronic disease

Answer 46

IL-22

Question 47

Which cell is implicated in inducing epidermal hyperplasia in more chronic disease

Answer 47

Th22 May be protective against Staphylococcus overgrowth

Question 48

Blocking _____ and _____ cytokines has the biggest impact on skin INFLAMMATION

Answer 48

IL-4 IL-13

Question 49

Blocking _____ cytokine has the best control for ITCH

Answer 49

IL-31

Question 50

In addition to keratinocyte, epidermal lipid, and inflammatory cells changes, which other cell is affected by atopic dermatitis

Answer 50

Nerves! Hyperinnervation

Question 51

Which 3 cell signals are implicated in hyperinnervation in cAD?

Answer 51

1) IL-31 2) NGF 3) Artemin (made when AHR is bound to pollutants)

Question 52

Other than itch, what other sensation is experienced with severe cAD?

Answer 52

Pain

Question 53

Receptors for which cytokines are present on neurons (5)

Answer 53

1) IL-31 2) IL-4 3) IL-13 4) TSLP 5) IL-33

Question 54

How do TRegs work? (5)

Answer 54

1) Produce inhibitory cytokines (IL-10, TGFbeta) 2) Suppress antigen presentation and ILCs via CTLA-4, ICOSL (inhibitory surface molecules) 3) Inhibit target cell metabolism 4) Induce cytolysis with Granzyme A and B 5) Impair B cell production of IgE

Question 55

What does IgE bind to?

Answer 55

IgE has two types of receptors: FcεRI, which is high-affinity, and FcεRII, which is low-affinity.

Question 56

T or F: IgE can be heat inactivated

Answer 56

True at 56C

Question 57

Which cell is increased in dogs with cAD that may produce IL-22 (epidermal hyperplasia) and IL-17A (attract neutrophils); help control dysbiosis

Answer 57

γδ T cells

Question 58

Which 2 cytokines do γδ T cells produce that may increase epidermal hyperplasia and neutrophil attraction in dogs?

Answer 58

IL-22 (epidermal hyperplasia) IL-17 (neuts)

Question 59

Name the Staphylococcus virulence factors (7)

Answer 59

1) Delta toxin: mast. cell degranulation 2) Protein A: (Protein A binds to the Fc region of Igs) 3) Toxins: SEA-U enterotoxin, TTST-1 exotoxin 4) Adhesins 5) Invasins: hyaluronidase, coagulase, staphylokinase 6) Microcapsule 7) Cell wall

Question 60

Which cytokines does Th1 make? (viral, intracellular pathogens)

Answer 60

TNF alpha IFN gamma LT

Question 61

Which cytokines does Th2 make? (allergy, parasites)

Answer 61

IL-4 IL-6 IL-13 IL-31

Question 62

Which cytokines does Th17 make (extracellular pathogens; NEUTROPHILS, autoimmunity)

Answer 62

IL-17 IL-22 TNF alpha

Question 63

Which cytokines does Th22 make? (Epidermal hyperplasia, resistance to staphylococcus overgrowth)

Answer 63

IL-22 TNF alpha

Question 64

Which cytokines does Th9 make? (Chronic inflammation, potential role in food allergy)

Answer 64

IL-9 = mast cell growth factor IL-10

Question 65

Which cytokines does Tfh2 make? (induce IgE, B cell function in LN)

Answer 65

IL-4 IL-6 IL-21

Question 66

Which cytokines does ILC2 make?

Answer 66

IL-4 IL-5 (eos) IL-13 IL-9 (chronic inflam, food allergy?) Enhance Type 2 immune response in cAD

Question 67

What stimulates ILC2 cells?

Answer 67

Epidermal alarmins (IL-25, IL-33, TSLP)

Question 68

T or F: Filaggrin mutations are necessary and sufficient to induce cAD

Answer 68

False. Filaggrin is neither necessary nor sufficient to induce cAD

Question 69

How does Staphylococcus affect basophils?

Answer 69

Enterotoxin can stimulate basophils to make IL-4

Question 70

T or F: histamine is the most important molecule for induction of itch in atopic dermatitis

Answer 70

FALSE NONhistaminergic pathway is more important (TSLP, IL4, IL13, IL31, IL33)

Question 71

Which cytokine has a vaccine against it, which shows some efficacy against IBH in horses

Answer 71

IL-5 IL-31 (itch not assessed, but decreased lesional scores)

Question 72

Does medication during ASIT affect its efficacy?

Answer 72

We don't know. In human medicine, it seems like it may help with efficacy of ASIT

Question 73

How does SLIT work to induce tolerance?

Answer 73

Antigen bound by sublingual oral DC --> presented to naive CD4+ T cell in LN --> naive T cell converted to FoxP3 Treg cell --> goes to tissue to induce tolerance

Question 74

What blocking antibodies are induced by ASIT, which limit IgE binding to Fc on MC, baso

Answer 74

IgG4, IgG1

Question 75

What makes IgE different than IgG

Answer 75

IgE has an extra portion on Fc region (3) Heat inactivated

Question 76

What is IgD

Answer 76

BCR

Question 77

Neurogenic cytokines

Answer 77

TSLP, IL-4, IL-13, IL-31, IL-33

Question 78

Adhesion molecule downregulated in cAD skin

Answer 78

Claudin --> skin barrier damage Tight junction

Question 79

What are the 2 signals helper T cells need to be activated

Answer 79

1) MHC cl 2 to TCR 2) CD28 to CD80/CD86

Question 80

How do superantigens contribute to Staphylococcal hypersensitivity

Answer 80

Dogs develop IgE AGAINST SUPERANTIGENS Superantigen presented to CD4+ by LC --> develop IgE against Staph superantigen --> Staph hypersensitivity

Question 81

What category of virulence factor are Staphylococcal superantigens

Answer 81

Enterotoxins

Question 82

Itch ion channels (2)

Answer 82

* TRPV1 * TRPA1

Question 83

What are the SEA-U and TSST1 impacts as superantigens

Answer 83

*Basophil activation --> release IL-4 --> more Th2 response *Activate T cell mediated inflammation (Th2)

Question 84

What do superantigens bind

Answer 84

Beta subunit of TCR Activate up to 20% of T cells May be involved in CAFR

Question 85

Main transcription factor for Th2 cells

Answer 85

GATA3

Question 86

Main transcription factor for Th1 cells

Answer 86

TBet