Research progress of keratinocyte‐programmed cell death in UV‐induced Skin photodamage

Abstract

Skin photodamage includes sunburn, phototoxic dermatitis, photosensitive dermatitis and photoaging. These common skin diseases that affect appearance are caused by ultraviolet radiation. The ultraviolet rays that reach the Earth are mainly divided into longwave ultraviolet rays (ultraviolet radiation A, UVA, 320 ~ 400 nm) and medium-wave ultraviolet rays (ultraviolet radiation B, UVB, 290 ~ 320 nm). UVA accounts for 95% of the ultraviolet radiation that reaches the Earth's surface 1 and leads to skin ageing and wrinkling because of cellular DNA damage by reactive oxygen species (ROS) production. 2,3 UVB is a major cause of skin reddening and sunburn through direct DNA damage. 3 Therefore, both types of UV radiation are chief causes of skin damage and can induce skin inflammation, ageing and eventually skin cancer. Human keratinocytes, as the outermost barrier of the skin, are the main target cells of UV radiation. Studies have shown that UV irradiation can induce different forms of programmed cell death (PCD) in keratinocytes, including apoptosis, pyroptosis, necroptosis and autophagy (Figure 1). In this review, we will briefly introduce the various types of PCD and their roles in UV-induced skin photodamage. | AP OP TOS IS | Introduction to apoptosisApoptosis is type of cell death in which the cell membrane remains intact. Apoptosis essentially does not induce inflammatory reactions. Initiator caspases (mainly caspase-2, −8, −9 and −10) and executioner caspases (such as caspase-3, −6 and −7) participate in the process of apoptosis. Apoptosis controls the development and homeostasis of multicellular organisms, and the distinct morphological characteristics of apoptosis are cell shrinkage and pyknosis,

GSDME deficiency leads to the aggravation of UVB-induced skin inflammation through enhancing recruitment and activation of neutrophils

“…Recently, RCDs were divided into different molecularly definitions of terms, for example, intrinsic apoptosis, extrinsic apoptosis, pyroptosis, necroptosis, and other modalities [ 3 ]. For a long time, apoptosis was identified to be the type of keratinocyte death in UV-challenged skin [ 4 ]. Recently, we reported that UVB radiation induces typical pyroptosis morphological change and activation of pyroptosis executor gasdermin E (GSDME) in human keratinocytes [ 5 ].…”

Curcumin Improves Keratinocyte Proliferation, Inflammation, and Oxidative Stress through Mediating the SPAG5/FOXM1 Axis in an In Vitro Model of Actinic Dermatitis by Ultraviolet

“…Excessive exposure of the skin to UV radiation causes oxidative stress, inflammation, immunosuppression, matrix metalloproteinase production, and DNA damage and mutations, resulting in skin photodamage [18]. Corneocytes, the main functional and structural component of the epidermis, account for more than 80% of epidermal cells and are the first line of defense against UV radiation [19,20]. Here, we constructed an in vitro AD model in UV-irradiated HaCaT cells and observed that UV irradiation dramatically stimu-lated oxidative stress and inflammatory responses in HaCaT cells compared to controls.…”

Cryptotanshinone protects skin cells from ultraviolet radiation-induced photoaging via its antioxidant effect and by reducing mitochondrial dysfunction and inhibiting apoptosis

“…Frontiers in Pharmacology frontiersin.org wavelength of UVB is short and UVB is mainly absorbed by the epidermis, resulting in skin sunburn, epidermal hyperplasia, and inflammatory reactions (Amaro-Ortiz et al, 2014;Battie et al, 2014), whereas UVA has long wavelengths and can penetrate deep into the dermis, making it a more significant factor in the induction of skin photoaging (Zarei and Abbaszadeh, 2019). Keratinocytes account for 90%-95% of epidermal cells and are the main target cells of UVB radiation (Tang et al, 2021). Fibroblasts are the main cells of dermis (Wong et al, 2016) and the main target cells of UVA radiation.…”