ICADA Skin Barrier

Question 1

Issues with TEWL, an INDIRECT measurement of skin barrier function (3)

Answer 1

*Room temperature
*Humidity
*Inter/intraobserver variability

Question 2

3 indirect measurements of skin barrier function that may be more reliable than TEWL

Answer 2

1) Corneometer (skin hydration)
2) pH meter
3) Colorimeter (erythema)

**Ideally: use above 3 in conjunction with vapometer for TEWL

Question 3

Which 2 skin barrier measurement modalities correlate with disease severity

Answer 3

*TEWL (more water loss = more severe dz)
*pH (more basic pH = more severe)

Question 4

How are ceramide levels in cAD dogs compared to healthy dogs?

Answer 4

Lower ceramides in cAD

Question 5

Which ceramides are decreased in cAD dogs?

Answer 5

1) Ceramide 1 (CER[EOS])
2) Ceramide 9 (CER[EOP])
3) Ceramide (CER[NP])

Question 6

How is the stratum corneum organized in atopic dogs?

Answer 6

Hexagonal lipid packing

Question 7

How is the stratum corneum organized in normal, healthy dogs

Answer 7

Orthorhombic packing

Question 8

Which ratio of ceramides is decreased in cAD dogs?

Answer 8

CER[NS] C44/C34

Lower ratio = more severe cAD

Question 9

Which dogs have a filaggrin SNP mutation associated with their cAD

Answer 9

Labrador retrievers in the UK

Question 10

Do most dogs with cAD have mutations in filaggrin?

Answer 10

No

Question 11

Why does Santoro think studies evaluating filaggrin in cAD dogs may be flawed?

Answer 11

Potentially were investigating Filaggrin 2, rather than filaggrin.

Filaggrin 2 is a component of cornified envelope, makes NMF

Question 12

Which enzymes are changed in nonlesional cAD dogs, compared to healthy dogs?

Answer 12

*Decreased Caspase-14 in cAD in 1 study
*Increased Caspase-14, Matriptase, Calpain-1 in another study

Question 13

Which proteins are decreased in cAD? (6)

Answer 13

*Claudin-1 (tight junction)
*Occludin (tight junction)
*Corneodesmosin
*E-cadherin (adherens junction)
*Desmocollin-1
*Desmoglein-1

Question 14

What are the 2 major microorganisms that are increased in cAD microbiome dysbiosis?

Answer 14

*Staphylcococcus pseudintermedius
*Malassezia pachydermatis

Question 15

Which bacterial phyla are present in both healthy and cAD dogs, but increased in cAD skin?

Answer 15

*Actinobacteria
*Proteobacteria
*Firmicutes
*Bacteroidetes
*Tenericutes

Question 16

Which Malassezia sp is predominant in healthy skin?

Answer 16

Malassezia globosa

Question 17

Which Malassezia sp is predominant in cAD skin?

Answer 17

Malassezia pachydermatis

Question 18

How long after allergy challenge does increase in abundance of Corynebacteria and Staphylococcus persist for?

Answer 18

2 weeks after remission of skin lesions

Question 19

Right after resolution of pyoderma treatment, how does the cAD skin microbiome compare to healthy skin?

Answer 19

Goes back to normal for 4 weeks!

However, decreased diversity recurs within 4-6 weeks

Question 20

Which bacteria have increased abundance in the external ear canal of cAD dogs?

Answer 20

*Staphylcococcus (Firmicutes)
*Ralstonia (Proteobacteria)

Question 21

Which bacteria have an increased abundance in HEALTHY external ear canals compared to cAD?

Answer 21

Escherichia sp

Question 22

Most common microbial SPECIES on healthy skin?

(Tang et al 2020)

Answer 22

*Cutibacterium acnes
*S. pseudintermedius
*Porphyromonas cangingivalis
*Capnodiales (unclassified fungal species)
*Alternaria sp

Question 23

Most common microbial SPECIES on cAD skin

(Tang et al 2020)

Answer 23

*S. pseudintermedius
*S. schleiferi
*Bacteriodes pyogenes
*Peptoniphilus grossensis

Question 24

Most common microbes in healthy ears

(Tang et al 2020)

Answer 24

*Cutibacterium acnes
*S. pseudintermedius
*Streptococcus sp.
*M. pachydermatis
*Capnodiales (fungal)
*Pleosporales (fungal)

Question 25

Most common microbes in cAD ears

(Tang et al 2020)

Answer 25

*Malassezia pachydermatis
*Staphylococcus pseudintermedius
*Staphylococcus scheliferi
+ Anaerobes
*Finegoldia magna
*Peptostreptococcus canis
*Porphymonas cangingivalis

Question 26

How does phototherapy affect the microbiome on cAD skin?

Answer 26

*DECREASED S. pseudintermedius with UVB phototherapy
*INCREASED Actinobacteria & Cyanobacteria

Question 27

How do Malaseb baths BIW affect the microbiome on cAD skin?

Answer 27

*No change in bacterial microbiome
*Decreased fungal diversity while using shampoo, but returned to normal after 4 weeks

Question 28

What are the 2 main host defense peptides?

Answer 28

*Beta-defensins
*Cathelicidins

Question 29

In dogs with cAD or infection, what happens to gene expression of host defense peptides?

Of protein expression?

Answer 29

INCREASED

BUT protein expression is NOT always decreased –>dysregulation of synthesis of host defense peptides

Question 30

Where are host defense peptides in cAD skin?

(Within keratinocytes or secreted?)

Answer 30

Retained within keratinocytes

Question 31

How is the action/function of host defense peptides in cAD skin compared to healthy skin?

Answer 31

Decreased functionality (lower antibacterial inhibitory effect)

Question 32

How is the dispersion of host defense peptides in cAD skin compared to healthy skin?

Answer 32

HDP are usually attached to skin surface, rather than secreted effectively

Question 33

What are the 3 major differences in host defense peptides in cAD vs healthy skin (and ears)

Answer 33

cAD has:
*Decreased secretion (retained in keratinocytes)
*Decreased dispersion (attached to skin surface)
*Decreased antibacterial efficacy