Neuromodulatory and anti-inflammatory ingredient for sensitive skin: in vitro assessment

Author: Samara Eberlin

Published at: October 27, 2014

28th IFSCC Congress (International Federation of Societies of Cosmetic Chemists); Paris, October 27-28, 2014.
Costa A, Eberlin S, Polettini AJ, Pereira AFC, Dolis E, Torloni LBO.

Sensitive skin is a condition that exhibits reduced tolerance to frequent or prolonged use of cosmetics and toiletries. A modern concept of an interactive network between neuropeptide release from cutaneous nerves and the immune system has been established for this condition, and its manifestation seems to occur due to increased permeability of the stratum corneum. In response to noxious stimuli, substance P and calcitonin gene-related peptide lead to vasodilation and mast cell degranulation, resulting in a process called neurogenic inflammation. Besides neuroendocrine processes, the classical pathways of inflammation are also activated as a consequence of the release of cytokines, histamine, and eicosanoids. These, in turn, increase the sensitivity of nociceptors such as TRPV1 (vanilloid receptor channel of transient V1), inducing hyperalgesia and further production of inflammatory mediators. In this study, we evaluated the effects of an active ingredient on the production of neuropeptide substance P (SP); eicosanoids prostaglandin E2 (PGE2) and leukotriene B4 (LTB4); histamine, TRPV1, and envelope proteins filaggrin and involucrin, using an in vitro model of human keratinocytes. Incubation of keratinocyte cultures with IL-1β promoted significant increases in the levels of SP, PGE2, LTB4, histamine, and TRPV1. Concomitant treatment of cell cultures with the active ingredient prevented the increase of all evaluated inflammatory mediators. In relation to SP, the active ingredient was able to reduce the levels by up to 5.6-fold compared to the IL-1β-stressed group. The active ingredient also reduced the synthesis of PGE2, LTB4, and histamine and decreased TRPV1 synthesis by up to 21.5%. Regarding the synthesis of envelope proteins, the active ingredient promoted increases of up to 3.4-fold and 2.3-fold for filaggrin and involucrin, respectively, compared to the control group. The physiopathology of sensitive skin consists of an inflammatory process resulting from the abnormal penetration of potentially irritating substances due to skin barrier dysfunction and changes in the production of local neuromediators. In this work, it was demonstrated that the active ingredient exerts a protective effect against the inflammatory reaction induced by IL-1β in human keratinocyte cultures. The results also showed the ability of the active ingredient to stimulate proteins involved in stratum corneum integrity. Taken together, these data suggest that the active ingredient might be considered an effective additive to skin care product formulations, contributing to the amelioration of the subjective neurosensory forms of discomfort.