Transcript SKIN CARE

SKIN CARE
TRAINING
Alain KHAIAT, Ph. D.
Vice President R&D Asia Pacific
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TRAINING CONTENT
• Skin physiology
• Cosmetic functions:
– mechanism
– ingredients used
– performance assessment
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Skin
• Is the external barrier of the body, both
physical and immunological
• Is the mirror of the state of health of the
body
Skin plays an essential role both in the
aesthetic and health field.
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SKIN PHYSIOLOGY
The skin is the outer most layer of the body. It
is constituted of 2 layers :
• epidermis
• dermis
which sit on the fat layer around the muscles.
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EPIDERMIS
The stratum corneum made essentially of
dead cells is exfoliating.
The space between the cells constitutes the
intercellular cement.
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DERMIS
The dermis is where the collagen and elastin
fibers are. These fibers are responsible for
the skin structure and elasticity.
They are degraded by enzymes called
collagenase and elastase which belong to
the class of “Matrix Metallo Proteases” or
MMP.
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OIL PRODUCTION
• Oil is produced in the sebaceous gland ,
production is stimulated by hormones
• Oil flows into the hair follicle then onto the
skin surface
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Oil Production
Normal hair follicle where sebum empties onto skin surface
through follicle opening
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COMEDONES
• Whiteheads are closed comedones. The
obstructed follicle prevents oil flow and
provides an oil reservoir for bacterial
growth. They lead to inflammation
• Blackheads are open comedones (follicle
obstruction). The color is melanin and
oxidized lipids, not dirt. The content is firm
and dilates the follicle, blackheads are not
inflammatory
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COMEDONES
Whiteheads or closed comedones
• stays beneath the skin. Slightly raised, light
coloured lesion
• Caused by build up of debris ( cells + sebum)
within follicle
Blackheads or open comedones
•a whitehead becomes a blackhead when
it enlarges until a dark plug protrudes through
the skin surface
* Both whiteheads and blackheads may stay
on the skin for a long time.
* Whiteheads and Blackheads are noninflammatory
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SOLAR SPECTRUM
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UVB DAMAGE
• UVB impact on DNA in the cell creating
damages which may lead to cancer
• P53 gene codes for a protein that allows
repair of the DNA or kill the cell if repair is
not possible: “sunburn cells”
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UVA DAMAGE
• UVA acts through an oxidative stress,
forming free radicals (reactive oxygen
species) that will damage the DNA
• Reactive oxygen species create damages
leading to cancer
• Pigment production is the defense
mechanism
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TRAINING CONTENT
• Skin physiology
• Cosmetic functions:
– mechanism
– ingredients used
– performance assessment
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COSMETICS
DEFINITION :
Products applied on the skin, hair, teeth or
teguments in order to :
• beautify
• perfume
• cleanse
• promote attractiveness
• alter the appearance
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COSMETICS : FUNCTIONS
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Cleansing
Moisturizing
UV protection
Aging - Wrinkle
Acne & Oily skin
Pigmentation
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CLEANSING
• Soap : high pH, low rinsability, high
irritation
– Some soap have high rinsability, low irritation
• Cream cleanser / Facial wash :
– rinse off : detergent-based, neutral pH,
irritation depends on detergent type and
concentration
– tissue off : leave on, emulsion-based, less
“fresh clean feel“
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RINSABILITY
• Measured by Fourrier Transform Infra Red
or FTIR : scanning of the skin before
application and after rinsing of a cleanser.
The difference is representative of the
quantity of product left on the skin.
• Digital imaging with proper light allows
also to evaluate rinsability
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IRRITATION
• Patch test
• Chromameter (red color)
• Trans epidermal water loss : TEWL
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CLEANSER FORMULA
A typical cleanser formula consists of :
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detergent
10 - 15 %
foam booster 0 - 2%
preservative < 1 %
fragrance
0 - 1%
water
Qs 100 %
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CLEANSER FORMULA
 Surfactants : usually combinations are used to
enhance lathering and reduce irritation. SLS is to
be avoided, it strips the skin of its lipids
contributing to irritation.
 Preservatives : allergy potential of formaldehyde
donors.
 Fragrance : known allergens (like Peru Balsam or
Musk Ambrette) have been banned. It is important
for the fragrance to meet IFRA guidelines
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MOISTURIZING
• Water, like air or light, is essential to life
• Moisturization is a woman’s main
expectation from a cosmetic product
• Dermatologists face dry skin condition
every day : physiological, pathological
(ichthyosis), therapeutic (PUVA, retinoids)
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WHERE IS THE WATER ?
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50% is intracellular
15% is extracellular
5% is plasmatic
30% is in the sweat glands
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MECHANISMS OF REGULATION
• Hydration through deeper layers
• Loss through evaporation
• Moisture retaining ability of the stratum
corneum, dependent on :
– Hydro Lipido Proteic film (HLP)
– Natural Moisturizing Factor (NMF)
– integrity of intercellular cement
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HLP FILM
• Originates from sebum and sweat secretions
• Composed of :
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–
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water
ions
amino acids
urea
- triglycerides
- cholesterol free & esterified
- squalene
- fatty acids
- waxes
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NMF
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Amino acids
Urocanic acid
Pyrollidone carboxylic acid : PCA
Electrolytes
Sugars
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INTERCELLULAR CEMENT
• Ceramides ( sphingolipides )
• Fatty acids ( Linoleic acid )
• Cholesterol ( free & esters )
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MOISTURIZING INGREDIENTS
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Occlusive agents
Structural lipids
Hydrophilic film forming agents
Humectants
NMF
AHA
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OCCLUSIVE AGENTS
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Vaseline, paraffin
Waxes of animal or plant origin
Some silicone oils or waxes
Some vegetable oil (sweet almond)
Some fatty esters (isopropyl myristate)
Fatty alcohols
older technique, often comedogenic
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STRUCTURAL LIPIDS
• Essential Fatty Acids (EFA : linoleic,
linolenic acids)
• Poly unsaturated fatty acids (PUFA : EPA,
DHA)
• Ceramides or pseudo ceramides
• Cholesterol
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HYDROPHILIC FILM FORMING
AGENTS
• GAG : glycosaminoglycans like Hyaluronic
acid or chondroitin sulfates
• Collagen
• Proteins
• Chitin or Chitosan
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HUMECTANTS
• Glycerin
• Propylene Glycol or Butylene Glycol
• Sugars
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NMF
• PCA
• Urea (below 10 %)
• Amino Acids or hydrolyzed protein
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AHA
At low concentration (< 2 % ) AHA are
moisturizing agents by creating hydrogen
bonds between the protein chains.
The most common are :
• glycolic acid
• lactic acid
• citric acid
• malic acid
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PERFORMANCE ASSESSMENT
• FTIR :the ratio of amide I to amide II peaks is
function of the skin hydration
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NMR : nuclear magnetic resonance
TEWL : trans epidermal water loss
Capacitance (Corneometer®)
Conductance (Skicon®)
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FORMULATION
Typically they are oil in water emulsions :
– water
– propylene glycol : penetration enhancer it
becomes irritating above 5%
– humectants, film forming agents, AHA, NMF
– emulsifiers : could contribute to irritation,
concentration to be kept to a minimum
– oils, fatty esters : some are comedogenic
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UV PROTECTION
Two types of filters are used :
• chemical
• mineral
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SOLAR SPECTRUM
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CHEMICAL FILTERS
• Limited spectrum, highly regulated
• Most common filters :
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cinnamates (UVB)
PABA (UVB)
Oxybenzone (UVA)
Avobenzone (UVA)
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MINERAL FILTERS
• Broad spectrum, filtering capacity function
of size, influence on product texture
• Most common filters :
– TiO2
– ZnO
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PERFORMANCE ASSESSEMENT
• SPF measurement in vivo : it is the ratio of
the minimum erythemal dose with and
without protection ( relates only to UVB
protection )
• in vitro measurements :
– Diffey method
– spectrophotometric absorption method
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AGING : INTRINSIC
• Program theory : each cell contains a clock
which control the number of multiplication
• Error theory : occurrence of errors in the
replication which eventually lead to cell
death
• Control theory : cells function is remotely
controlled by secretions ( hormones )
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AGING : EXTRINSIC
• Sun : UVA / UVB / IR
• Psycho social factors : overwork, stress
• Dietary factors : insufficient water supply,
vitamin deficiency, alcohol, smoking
• Iatrogenic factors : corticosteroids,
ionizing radiation, diuretics
• Pathological factors : genodermatose,
acrogenia
• Hormonal factor : menopause
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MANIFESTATIONS OF SKIN AGING
• Epidermis :
– reduction in cell renewal rate
– thickening of stratum corneum
– decrease in barrier efficiency : increase in
TEWL and hyperkeratosis
– ridges are flattened out and intercellular
spaces enlarged
– pigmentation problems : actinic lentigines
– decrease in skin immune system
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MANIFESTATIONS OF SKIN AGING
• Sebaceous glands :
– reduction in sebum secretion (hormones
influenced)
• Sweat glands :
– less active
• HLP film :
– thinning of film means less protective barrier
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MANIFESTATION OF SKIN AGING
• Dermis :
– destruction of collagen and elastin fibers
network
– proteoglycans and glycoproteins are reduced
– increase in elastin synthesis : elastosis
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WRINKLES
• Expression lines :
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they are the first manifestation
due to constant creasing of the face
accentuated by environmental factors
they appear around the eyes (crow’s feet), the
nose and mouth (naso-labial fold), forehead
(frown lines)
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WRINKLES
• Gravity lines :
– skin and muscle structure become slack and
droops downwards
– subcutaneous tissues tend to sag
– flabby cheeks, double chin, bags under the
eyes and drooping eyelids
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WRINKLES
• Elastosis wrinkles :
– due to UV radiation, the epidermis is injured
(free radicals), the fibroblasts in the dermis
are over-active and abnormal deposits of
elastin occur
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ANTI AGING : PREVENTION
• Protective agents :
– sun protection
– anti free radicals : SOD, Se, Si, Vit. E, Vit. C,
carotenoids, flavonoids, -orizanol
• Nourishing agents
– vitamins : A (esters), B5 (panthenol), C, E, EFA
(linoleic & linolenic acids), PUFA
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ANTI AGE : PREVENTION
• Moisturizing agents
• Metabolism activators :
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unsaponifiable lipids (phytosterols)
plant extracts (Centella asiatica, Ginseng)
microalgae extracts
Bacteria, fungal or yeast extracts
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ANTI AGING : PREVENTION
• Conditioning agents :
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–
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anti MMP (elastase, collagenase)
hyaluronic acid
collagen, elastin (hydrolyzed)
nucleic acids (DNA, RNA)
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ANTI AGING : REPARATION
• Retinol : transformed into the skin in
retinoic acid, it has its positive properties
without the irritation
• AHA’s work by reducing the corneocytes
cohesion, increasing desquamation (cell
renewal), hydration and plasticity
• Vitamin C
• micro circulation activators : plant extracts
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PERFORMANCE ASSESSMENT
• Cutaneous relief :
– imprint techniques : micro depressionary
network, profilometry
– macrophotography : visible, UV light
– confocal microscopy
– biopsy
• Cell renewal :
– use of a dye : danzyl chloride or dihydroxy
acetone (DHA)
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PERFORMANCE ASSESSEMENT
• Alternative methods :
– used to determine the activity of ingredients
on molecules, cell cultures or skin replica
• Physiological parameters :
– hydration
– elasticity : cutometry, twistometry,
balistometry
– pigmentation : photography, chromameter
– vascularisation : Laser Doppler Velocimetry
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COSMETIC ACNE: from physiology
to treatment
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ACNE
• 95% of the population is affected at one
time or another by ACNE
• ACNE affects 85% of the teenagers:
– 10% require medical attention: severe acne
with 1% difficult to treat
– 90% have mild acne or cosmetic acne
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• Puberty : period over which the
secondary sexual characters gradually
become manifest as the reproductive
system develops to full capacity and
there is rapid somatic growth.
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Onset of puberty in girls
• Breast development following the increase
of estrogen from the ovaries
• Menstruation
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Puberty and Adolescence
• Adolescence is a difficult period for most
people: period of changes
• Herd bonding & sexual involvement
• Adolescence is a particularly bad time to
have skin problems, especially on the face
or on the extremities
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Physiological changes in the
skin during puberty and
adolescence
• Increase in sebum production: oily skin
and hair
• Onset of "body odor"
• Anguish in young men when male-pattern
balding begins in the teenage years
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Ideal skin for girls
• Skin should be oil-free with no pimples or spots
• Plenty of hair on head, but none on face, under the
arms or on the legs
→ puberty makes this ideal image virtually
impossible to achieve
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Acne vulgaris (Pimples)
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• Acne : a disorder of the pilosebaceous
unit, occurs in both sexes but is more
distressing to the women, not only
because of the cosmetic effect but
because of the frequent permanent
scarring
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ACNE
Normal hair follicle where sebum empties onto skin surface
through follicle opening
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Classification of acne
• Non-inflammatory lesions: open & closed
comedones
• Inflammatory lesions: papules, pustules,
nodules, cysts
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Pathogenesis of acne
• Sebaceous glands hyper-activity
• Pilosebaceous duct obstruction
• Bacterial colonization and inflammation
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The cause of acne (1)
The effect of Androgen hormones
I’m Androgen
Increases sebum secretion
Hyperkeratinization
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The cause of acne (2)
The effect of Propionobacterium acnes
We love
sebum
Hydrolyzes sebum
Free fatty acids
Inflammatory acne
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ACNE TREATMENT
• Drugs
• Dermatological Procedures
• Cosmetics
and/or
• Squeeze the pimple
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DERMATOLOGICAL PROCEDURE
• Peeling with drying and keratolytic agents : sulfur,
salicylic acid, resorcinol, benzoyl peroxide
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COSMETICS
• Traditionally the anti-acne approach has
used drying keratolytic ingredients:
– Benzoyl peroxide (5 or 10%)
– Salicylic acid (0.5 or 2%)
– Sulfur (~2%)
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OILY SKIN
Ingredients usually used to reduce shine :
• clay (bentonite)
• talc
• Kaolin
These ingredients will increase oil production
Ingredients used to control oil secretion:
• Soy/Wheat protein
• Cedarwood
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OILY SKIN
Efficacy is measured by :
• Sebumeter® : measure of the absorbance
of a tape
• Sebutape®
• removal of lipids and determination of
quantity
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PIGMENTATION
• Melanins are the result of the
transformation of Tyrosine into DOPA then
Dopaquinone by Tyrosinase in the
melanocyte.
• Melanins are transferred from the
melanocyte to the keratinocyte layers
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Pigmentation Formation Mechanism
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2
Irritation
UV
• Variety of Causes
• Variety of Responses
Inflammatory Response
KERATINOCYTE
(Epidermis)
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Hormone
Tyrosine
Melanin
MELANOCYTE
(Basal Layer)
Melanosome
Tyrosinase
FIBROBLAST
Dermis
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PIGMENTATION
Ingredients used to decrease pigmentation :
– hydroquinone : effective but not safe
– ascorbic acid derivatives
– plant extracts : Kojic acid, arbutin, Licorice,
Centella, Bayberry extract
Except for Hydroquinone, the skin lightening
effect is only visible after several weeks.
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PIGMENTATION
• Efficacy is measured by :
– Chromameter® : L measure
– Mexameter® : evaluation of melanin and
redness
– Photography : visible, UV with data analysis
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THANK YOU
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