SUMMARY AND CONCLUSIONS

Cosmetic Formulation of Skin Care Products

New and exciting discoveries have been made in SC biology over the last decade, but more importantly the understanding of the aberration of the normal functioning of the SC in dry, flaky skin conditions has become clearer and a new model of dry skin has been described. On perturbation of SC barrier function, a futile cycle of events begins first with the superficial dehydration of the SC and subsequent release of inflammatory mediators, induction of hyperproliferation of epidermal keratinocytes, and disruption of epidermal

SUMMARY AND CONCLUSIONS

(A)

 

D= Corneodesmosome
E= Stratum corneum enzymes
e=Intracellular enzymes

 

Enzyme mediated degradation of

corneodesmosome and lipids, weakening of barrier and loss of NMF

Enzyme diffuses towards corneodesmosomes to begin their degradation and encapsulation with barrier lipids, transformation of fragile to resilient corneocyte

Intact corneodesmosomes anc normal lipid bilayers, filaggrin hydrolysis dependent on water activity

 

SURFACE LAYERS OF

STRATUM CORNEUM

 

INNER LAYERS OF

STRATUM CORNEUM

 

(B)

 

Intact corneodesmosomes, reduced enzyme activity, lipid disruption, decreased lipids leading to abnormal barrier function, excessive loss of NMF and retention of fragile corneocyte phenotype

Intact corneodesmosomes
and lipid disruption,
lack of maturation of corneocytes
reduced Tgase activity

 

D= Corneodesmosome E= Stratum corneum enzymes e=Intracellular enzymes

 

SURFACE LAYERS OF

STRATUM CORNEUM

 

INNER LAYERS OF

STRATUM CORNEUM

 

Intact corneodesmosomes
and normal lipid bilayers

 

RELEASE OF INFLAMMATORY MEDIATORS AND PROTEASES

 

SUMMARY AND CONCLUSIONSSUMMARY AND CONCLUSIONS

SUMMARY AND CONCLUSIONS

Figure 24 Summary of stratum corneum maturation and comeodesmolysis in (A) normal and (B) dry skin. Source: From Ref. 2.

differentiation, leading to an inferior SC. As has become apparent, reductions in SC water and NMF levels, changes in lipid ultrastructure, and reductions in enzyme activities contribute to the reduced corneodesmolysis known to occur in these conditions. See Figure 24 for a schematic summary of the differences in SC biology in normal and dry skin. As a result, new therapies for the treatment of dry skin have been developed that target all aspects of the aberrant biology described by the “dry skin cycle.”

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Updated: June 20, 2015 — 3:09 am