733 Potent immunogenic cell death (ICD) caused by UVA-Activated 8-Methoxypsoralen (8-MOPA)

Abstract

The vascular and inflammatory response in Rosacea is exacerbated by exposure to UV radiation. In this study we hypothesized that the excess LL37 known to be present in Rosacea skin may be responsible for this increased sensitivity to UV. To test this, human keratinocytes (NHEK) expressing LL37 were exposed to UVB (25 mJ/cm 2 ), then extracts from these cells, or control cell extracts of non-irradiated NHEK, were added to dermal microvascular endothelial cells (HDMECs). UV-damaged NHEK, but not controls, activated endothelial cells as seen by increased CXCL10 (4.03 fold, p¼0.03) and CX3CL1 (13.6 fold, p<0.0001). This activation of endothelial cells was due to release of dsRNA from UV exposed NHEK since RNAase treatment of the NHEK extract inhibited the response of HDMECs. HDMECs treated with a synthetic dsRNA (snoU1 RNA) required LL37 for activation, a process we refer to as innate immune vetting. To further understand the significance of this vetting phenomenon in rosacea, RNA-sequencing was performed on HDMECs. 117 unique genes were upregulated only by the combination of dsRNA and LL37. As expected, a GO pathway for type I interferon signaling was seen, but HDMECs also showed gene signatures for cell-cell adhesion. q-RT-PCR then validated induction of ICAM1 (10.74 fold, p¼ 0.0406) and VCAM1 (13.9 fold, p¼ 0.0051) by LL37-dsRNA. The role of dsRNA was confirmed by knock down of TLR3 (VCAM1 inhibited 6.02 fold, p¼ 0.0017). Consistent with induction of VCAM1 by RNA-LL37, we also observed that dsRNA-LL37 increased VCAM protein expression, enhanced monocyte adhesion to HDMECs (76.51 fold, p<0.0001), and increased leukocyte transmigration (5.11 fold, p<0.0001) across HDMECs. In mice, only combined injection of U1 and LL37 enhanced VCAM1 expression. These findings prompted examination of human Rosacea biopsies that also showed VCAM1 to be highly expressed in rosacea skin, a finding not previously known in this disorder. Overall, our results suggest LL37 acts as an innate immune vetting molecule in rosacea that enhances activation of endothelial cells after UV exposure. Premature skin aging evidenced by a rough skin texture and wrinkles is known to be driven by external factors, mainly by sunlight and in particular UV radiation including UVB (280-320 nm) and UVA (320-400 nm). However, recent advance highlighted the role of visible light and especially the blue light part (400-500nm) in skin aging. As the blue light is the highest energetic wavelength of the visible light, it penetrates deeper into the skin and damages the skin by inducing oxidative stress and production of proteases which degrade the extracellular matrix of the dermis. We first investigated the negative effects of the blue light in human dermis through the evaluation of MMP1 by immunostaining and image analysis on living skin biopsies exposed to blue light irradiation (peak at 250 nm-85 J/cm 2 ). We further evaluated the blue light preventive effect of a botanical extract selected for its ability to prevent UVB induced oxidative damages by promoting DNA ...

Xanthotoxin (8‐methoxypsoralen): A review of its chemistry, pharmacology, pharmacokinetics, and toxicity

“…In clinical practice, we use 8‐MOP at a concentration of about 2.6 mg/L, the wavelength of UVA is 325 nm (Al‐Ismail, Edwards, & Anstey, 2016). 8‐MOP inhibits epidermal thickening (Alalaiwe et al, 2018), ragging (Hayashi, Ikeda, Kitamura, Hamasaki, & Hatamochi, 2012), and wrinkles (Zhou et al, 2020), upregulated the level of P16, a channel protein associated with aging, and down regulates the level of miR27a and 29a (Shirsath et al, 2018; Singh, Schn, Wallbrecht, & Wolf, 2012; Tatsuno, Hanlon, Yamazaki, Galluzzi, & Edelson, 2019), thereby inhibiting the secretion of interferon‐gamma (IL‐γ), IL‐17, and IL‐19.…”

“…In clinical practice, we use 8-MOP at a concentration of about 2.6 mg/L, the wavelength of UVA is 325 nm (Al-Ismail, Edwards, & Anstey, 2016). 8-MOP inhibits epidermal thickening (Alalaiwe et al, 2018), ragging (Hayashi, Ikeda, Kitamura, Hamasaki, & Hatamochi, 2012), and wrinkles (Zhou et al, 2020), upregulated the level of P16, a channel protein associated with aging, and down regulates the level of miR27a and 29a (Shirsath et al, 2018;Singh, Schn, Wallbrecht, & Wolf, 2012;Tatsuno, Hanlon, Yamazaki, Galluzzi, & Edelson, 2019), thereby inhibiting the secretion of interferon-gamma (IL-γ), In addition, the development of psoriasis is also related to the immune system (Trautinger, 2018), and PUVA is often used in combination with immunosuppressive columns such as methicillin to improve the efficacy (Jagasia et al, 2019), and Extracorporeal photopheresis (ECP) is immunotherapy mainly used to inhibit dendritic cells (DCs) maturation (Failli et al, 2011), induce apoptosis (Hahnel et al, 2021), and regulate the function of T lymphocytes and B lymphocytes (Futterleib, Feng, Tigelaar, Choi, & Edelson, 2014;Wei, Sun, Xiao, & Shi, 2018). The core of ECP lies in the induction of immune tolerance and enhanced cytotoxicity through apoptosis of the patient's leukocytes (Budde, Berntsch, Riggert, & Legler, 2017;Holien, Gederaas, Darvekar, Christensen, & Peng, 2018).…”