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Skin barrier function, skin conductivity

Skin barrier function, skin conductivity. Michal Jurajda. Terminology. Keratos = horn in Greek Cornu = horn in Latin. Skin is the body organ. epidermis. skin adnexa. +. dermis. tela subcutanea. Skin functions. Barrier functions (phys., chem. and biol.)

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Skin barrier function, skin conductivity

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  1. Skin barrier function,skin conductivity Michal Jurajda

  2. Terminology • Keratos = horn in Greek • Cornu = horn in Latin

  3. Skin is the body organ epidermis skin adnexa + dermis tela subcutanea

  4. Skin functions • Barrier functions (phys., chem. and biol.) • metabolic functions (vit.D activation, excretion) • immune function, APC (Langerhansovy buňky) • Senzoring of temperatute and pain • Thermoregulation

  5. Stratum corneum Skin barrier - epidermis • Epidermal layers Stratum dysjunktum Stratum compactum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale

  6. Skin barrier • System of two compartments • „ bricks and mortar “ • keratinocytes (corneocytes) • intersticium

  7. Skin barrier • „Bricks“ • Keratinized cells • „Mortar“ • Produced by keratinocytes (Odland bodies, lamellar bodies) • Excretions of skin glands • FFA, ceramids, cholesterol

  8. Skin barrier – cellular component • Mechanic function • Hydratation • UV protection • Inflammatory response (APC)

  9. Keratin • Epithelial cells almost always coexpress pairs of type I and type II keratins, and the pairs that are coexpressed are highly characteristic of a given epithelial tissue. • In human epidermis, 3 different pairs of keratins are expressed: keratins 5 (type II) and 14 (type I), characteristic of basal or proliferative cells; keratins 1 (type II) and 10 (type I), characteristic of suprabasal terminally differentiating cells; and keratins 6 (type II) and 16 (type I) and keratin 17 (type I), characteristic of cells induced to hyperproliferate by disease or injury, and epithelial cells grown in cell culture.

  10. Filaggrin • Protein from corneocytes • In the deeper layers of epidermis connected to keratin • In the upper layers of epidermis is hydrolyzed. Free aminoacids are released. • Acidic pH and osmotic activity

  11. UCA urocanic acid • Originates from filaggrin. • Acidic pH of the epidemmis • Natural sunscreen • Cis-UCA immunosupression

  12. Skin damage by UV rays • direct • pyrimidin dimers formation – mostly thymin (UVB) • photoageing – induction/inhibition of gene expression (↓colagen, ↑MMPs, ↑elastase) • indirect • ROS formation (following excitation of „chromophores“ – molecules containing conjugated double bonds and/or aromatic circles) • retinoid depletion in skin • imunosupression (esp. UVA) • folate degradation – systemic effects

  13. Melanin – protection against ultraviolet radiation

  14. Interstitial compartment • Permeability • Deskvamation • Antimicrobial effect • Absorption of drugs or poisons • Hydratation

  15. Lamellar bodies (LB) • Lipids + enzymes producing FFA cholesterol a ceramids - permeability • Structural proteins (corneodesmin), serine proteases, proteases inhibitors – regulation of skin desquamation • Antimicrobial peptides (βdefensins, cathelicidiny – evolutionary old proteins)

  16. Cosmetics and the skin barrier • Cosmetics x pharmaceuticals • Different sale regulations • Different declaration of ingredients • Cosmetics: according to % in content • Pharmaceuticals: according to active component

  17. INCI • International Nomenclature Cosmetics Ingredients – unified nomenclature for cosmetics • Cosmetics, Toiletries & Fragrance Association (CTFA) – author of INCI

  18. Examples

  19. Skin cleanser cosmetics

  20. The importance of skin barrier function – why we are interested in? • Protection against environment • Professional exposure • Skin diseases influence skin barrier • Atopic or contact dermatitis • Drugs absorption

  21. How to test skin barrier • Resistence against given chemical compound • Stripping tests • Transparency test • Transepidermal water loss • Chemical analysis of skin eluates

  22. Transparency test

  23. Atopic dermatitis • Sensibilization • Allergic reaction

  24. Atopic dermatitis

  25. Prick test

  26. Contact dermatitis • Haptens • nickel

  27. Skin barrier tests • Burckhardt test • Locher test, nitrazolium yellow • Skin conductivity

  28. Measuring of skin conductivity by Dermotest • AC 32Hz; 0-500 μS. • standard load iontophoresis 1.5 mA, with NaCl (physiological saline).

  29. The device measures 5 characteristic values (V1-V5): 1min after the start (V1) 30 a 60s after the start of electrophoresis (V2, V3) 30 a 60s after switching off the electrophoresis(V4, V5)

  30. Normal values • V1 less than 30 μS • V3 up to 200-300 μS • V5 return to initial values • Test might be repeated after 15 minutes with the same result

  31. desquamation

  32. occlusion

  33. Course of atopic dermatitis therapy

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