Dermatology Flashcards
What are physiological functions of the skin? (9)
- Protection (physical & immune)
- Skin microbiome
- Thermoregulation
- Sensation
- Water storage
- Absorption
- Secretion
- Facial expression
- Synthesis of vitamin D
What is the most prominent innate immune cell subset of the skin?
Mast cells
Which part of the immune system can the skin be considered to be part of?
Innate immune system
What is the sex difference in immunity?
Androgen signalling in males skews skin immunity towards reduced inflammation
Women are more predisposed to auto-immune disease, but also better protected against infectious disease & tumours
What is a remarkable property of the skin in regards to its ability to induce an adaptive immune response?
All cells required to produce an antibody response are present in the skin -> lymph nodes not always necessary
Why is it important that the skin can quickly produce a humoral immune response without relying on lymph nodes?
Regulation of skin microbiota
[Infectious diseases/auto-immune diseases] of the skin usually have more systemic symptoms when compared to the other
Infectious diseases generally give more systemic symptoms than auto-immune diseases
How do susceptibility genes influence the chance of leprosy of the skin?
Genetic predisposition to stronger humoral immunity = higher bacterial load
Genetic predisposition to stronger cellular immunity = lower bacterial load
Why is cellular immunity important to lower leprosy bacterial load?
Leprosy = intracellular pathogen
Why is psoriasis protective for leprosy?
Psoriasis = overactive cellular immunity
Which cell type is especially prominent in combating fungal infections of the skin?
Th17-cells
Why do anti-IL-17 biologicals cause skin infections?
They inhibit the Th17 signalling important for preventing fungal disease (mainly Candida)
Which type of infection is frequently seen in patients using anti-IL-17 biologicals? Why?
Candida infections -> these biologicals block Th17 function, which is important to prevent fungal infection
What are essential roles of the skin microbiota? (3)
- Protection against invading pathogens
- Education of the immune system
- Breakdown of natural products
True or false: skin microbiota cannot enter hair follicles and glands of the skin
False; the hair follicles and glands form specific niches for microbiota
What kind of bioactive molecules are produced by skin commensals? (6)
- Antimicrobial peptides (AMPs)
- Free fatty acids (FFAs)
- Structural components
- Phenol-soluble modulins (PSMs)
- Cell wall components
- Antibiotics (produced by fungi)
What are important functions of the bioactive molecules produced by skin commensals? (3)
- Prevent pathogen invasion
- Activate keratinocytes to produce immune factors
- Stimulate immune cells native to/passing through the skin
What are the characteristics of the skin micriobiome environment? (6)
- Low biomass
- High lipid
- High salt
- Dry
- Nutrient-poor
- pH 5
What are the characteristics of the gut micriobiome environment? (6)
- High biomass
- High saccharide
- Low salt
- Moist
- Nutrient-rich
- pH 7
In which part of the colon is the oxygen tension highest?
In the crypts
Skin microbiota in hair follicles [are secluded from the outside environment/intract with the outside environment]
Skin microbiota in hair follicles have little turnover with the outside world and stay in their specific niche
Gut microbiota in colonic crypts [are secluded from the outside environment/intract with the outside environment]
Gut microbiota in the crypts are actively turned over with the lumen
Which two classes of lipids are produced by the skin?
- Epidermal lipids
- Sebaceous lipids
By which cells/organs are epidermal lipids produced?
Keratinocytes