Role of Proteases in Photo-aging of the Skin
Aging is an inevitable process in living organisms that results from molecular damage over time. The skin being the most exposed part of the body, time and environmental aggressor leave their indelible mark on the skin. So, skin aging consists of two clin
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20
Rita Ghosh
Abstract
Aging is an inevitable process in living organisms that results from molecular damage over time. The skin being the most exposed part of the body, time and environmental aggressor leave their indelible mark on the skin. So, skin aging consists of two clinically and biologically independent processes – the intrinsic chronological aging and the aging through extrinsic factors. While intrinsic aging process proceeds at a genetically determined pace due to buildup of damaging products from cellular metabolism, exposure to solar radiations produces biological damages to the cells, known as photo-aging. It adds up to the effects of chronological aging, and it is the most prominent and important among the extrinsic factors. The normal architecture of the skin is disrupted due to degradation of skin components like collagens, fibers, etc. Photo-aged skin presents fine and coarse wrinkles with blotchy pigmentation, increased fragility, and rough texture. It results from complex biological phenomena that lead to activation of several proteases; the most crucial among them are the matrix metalloproteases (MMPs). UV irradiation generates reactive oxygen species and activates a number of transcription factors like AP1, NF-κB, p53, and growth factor like TGFβ. These, in turn, stimulate the MMPs and other proteases. UV radiation also inhibits the expression of natural inhibitors of MMP (TIMP), thereby enhancing the activity of the MMPs. Understanding of the molecular basis of photo-aging is important for its prevention and effective recovery. Antioxidants and other com-
R. Ghosh (*) Department of Biochemistry & Biophysics, University of Kalyani, Kalyani 741235, West Bengal, India e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2017 S. Chakraborti, N.S. Dhalla (eds.), Proteases in Physiology and Pathology, DOI 10.1007/978-981-10-2513-6_20
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R. Ghosh
pounds that inhibit the molecular pathways that result in expression of the proteases have proved to be useful in prevention/reversal of skin aging. Keywords
Photo-aging • Ultraviolet radiation • Skin • Proteases • Prevention
20.1 Introduction Aging is an inevitable process common to all living organisms that result from molecular damage over time. The skin is the largest of all organs of the human body that constitutes about 16% of the total body weight. It maintains body temperature and hydration; it also has roles in sensory perception and immune surveillance. It acts as a barrier between the inner body parts and the environment [1]. Being the most exposed part of the body, different environmental aggressors leave their mark on the skin. The skin is thus a good model for studying the consequences of aging. Skin aging consists of two clinically and biologically independent processes – the intrinsic chronological aging and the other is due to aging through extrinsic factors. The intrinsic aging process proceeds at a genetically determined pace due to buildup of damaging products from cellular metabolism and is similar in all
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