Anne Guzman-Struillou, David Boudier, Florence Lalande, Magalie Pinel, Brigitte Closs – Silab, France
SKIN CARE
Targeting the Ah receptor: a new antipollution strategy
Today’s lifestyles expose the body to all sorts of constant environmental stress which is difficult to avoid in a continuous and efficient way.
Our atmosphere is composed of about 80% nitrogen and 20% oxygen, with traces of argon and other inert gases, and increasing quantities of carbon dioxide. The air we breathe also contains more than 2,800 chemical compounds,1
several
of which are known to adversely affect health. Among the latter are polycyclic aromatic hydrocarbons (PAH) that are considered one of the major families of atmospheric pollutants. PAH are organic compounds resulting from the incomplete combustion of organic matter (coal, petroleum products, wood, etc). This family has more than 100 members, many of which are related to public health issues, in particular some of them are as harmful as benzo[a]pyrene (BaP), also found in cigarette smoke.2
Considerable work over the past several years has been conducted in order to determine which major biological constituents are involved in the cellular response to pollutants. Among these constituents, the aryl-hydrocarbon receptor (AhR) has been found to be a very interesting biological target. It plays a key role by detecting pollutants and by reflecting their biochemical and toxic effects. In the skin, the Ah receptor is constitutively expressed in the Langerhans cells, fibroblasts and melanocytes and in a major way in the keratinocytes.3 Stabilised in an inactive form in the cytoplasm, AhR, once activated by a ligand such as BaP, gets into the cell nucleus where it combines with a co-activator, AhR nuclear translocator (Arnt). The AhR/Arnt complex acts as a transcription factor and activates the CYP1A1 expression.4,5 By metabolising xenobiotics, CYP1A1 generates bioactive molecules which cause the excessive production of free radicals overburdening the skin’s natural antioxidant systems.
Chronic exposure to environmental pollutants, even at low doses, leads to the prolonged activation of the AhR-CYP1A1
ABSTRACT
Urban pollution, chemicals and cigarette smoke damage the skin and gradually lead to its premature ageing. Skin cells detect pollutants thanks to molecular detectors such as aryl-hydrocarbon receptors (AhR). Once activated, the AhR regulates the expression of target genes, such as CYP1A1 (or aryl hydrocarbon hydroxylase). The sustained induction of the AhR-CYP1A1 pathway through daily exposure to environmental pollutants is responsible for the harmful pollution-related effects. An active ingredient obtained from dandelions Taraxacum officinale (dandelion) extract (TE) has been developed to regulate activation of the AhR-CYP1A1 signalling pathway. In addition, in vivo studies have shown that TE reduces levels of oxidised proteins and improves the complexion radiance.
This active ingredient restores the skin’s natural protective shield. It is recommended for all skin care products intended to attenuate the harmful effects of pollution.
developed an innovative natural active ingredient, Taraxacum officinale (dandelion) extract (TE), derived from dandelion, a plant known for its detoxifying properties. For the first time in cosmetics, this active ingredient targets the AhR-CYP1A1 pathway, whose antipollution cosmetic benefits on skin have been proven by placebo-controlled studies on polluted skin.
Materials and methods In vitro studies
Study of nuclear translocation of AhR and of the expression of CYP1A1 on normal human keratinocytes Activation of the AhR is shown by: translocation of this receptor from the cytoplasm to the nucleus
activation of the expression of CYP1A1 (target gene of the AhR).
Urban pollution causes premature ageing
pathway, in turn leading to harmful effects in the skin. These effects are shown by a dull complexion, under-eye bags and pigmentation disorders that cause premature ageing of the skin.2,6 The cosmetics industry is constantly developing new and effective antipollution strategies in order to respond to the expectations of urban consumers whose skin is systematically exposed to a polluted environment.
In this context, Silab’s research has
The capacity of TE to limit the activation of AhR after the exposure of normal human keratinocytes in culture to a pollutant such as BaP was determined by Western blot. The level of expression of CYP1A1 was determined by quantitative RT-PCR. The mRNA of HPRT protein, the internal standard, was also analysed in parallel to mRNA of CYP1A1.
Fluorescence incorporation (SYBR Green) was quantified continuously with a thermocycler (Roche LightCycler LC480). Analysis of Ct (relative quantification) was done with LC480 software (Roche).
September 2015 PERSONAL CARE 77
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