March 2023 • Vol. 29 • Issue 3
Peroxisome Proliferator-Activated Receptors Reemerge as a Skin Wellness Target in Cosmetics
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…Marc Cornell
osmetics continue their marvelous evolution with new scientific findings and breakthrough innovations. Sometimes we need to look back to find the genesis of a current marketing or positioning trend. Take a step back with me to the late 20th century, where a young researcher was being educated in the biology of wound healing. During this time, I became aware of peroxisome proliferator-activated receptors (PPARs). PPAR-alpha expression plays a role in the inflammatory stage of wound healing. Later I learned wound healing shares many biologic pathways with anti-ageing biology. PPARs is a mouthful, right? Let’s dial it back bit and keep the PPAR focus on our body’s largest organ, the skin. PPARs are ligand inducible transcription factors belonging to the nuclear hormone receptor superfamily. The key isoforms of PPARs are notated as alpha, beta/delta, and gamma. These forms can up regulate or down regulate many cellular and metabolic processes such as cellular differentiation, proliferation, lipid homeostasis, and energy metabolism. These functions are critical to our body and its skin’s immune system, epidermal barrier function, and development of pro-inflammatory signals. PPARs are also involved in regulating and modulating glucose levels, lipid homeostasis, and mitochondrial function.1 It is obvious that regulation of PPAR signaling to various biological systems is an opportunity for medicine and cosmetic science. In some studies, regulation of PPAR signaling has been linked to disease pathogenesis. These ailments have complex causes involving genetic, environmental, and nutritional factors—PPARs are just a part of the pathway.2 In cosmetic science we are careful to draw the line between drug and cosmetic claims. With that said, there are numerous scientific studies elucidating shared connections between drug and cosmetic active biologic modes of action. How can cosmetic science leverage PPARs to facilitate skin wellness? We start our PPAR discussion by looking at the skin barrier function. This area of skin biology is also part of a recent trend towards minimizing environmental stressors on the exposome. The exposome is defined as the measure of all the exposures of an individual in a lifetime and how those exposures relate to health. PPAR activation has been shown to have an important role in skin barrier function by regulating differentiation and lipid synthesis in keratinocytes.3 This fact fits nicely into homeostasis wellness positioning. PPAR activation takes place through heterodimerization. Simply put, you need two ligands to come together on the DNA to initiate gene regulation. PPAR activators are already being used in areas of cosmetic science. Botanical extracts have been shown to activate PPARs in the stimulation of collagen in skin.4 There is also evidence that PPARs may be used as an alternative to retinoids in skin care.5 In addition, PPARs have an important effect in keratinocyte homeostasis, suggesting a role in diseases such as psoriasis.6 Furthermore, PPARs act directly to negatively regulate gene
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...see pages 5-7 for more information.
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