Ultraviolet (UV) eye irradiation denatures the cells of the intestine. This study examined the action of UVA and UVB on dextran sodium sulfate (DSS)-induced ulcerative colitis. We produced a mouse model of ulcerative colitis by administering DSS for 5 days and irradiated the eye with UVB or UVA for each day of the DSS treatment period. DSS-induced ulcerative colitis was deteriorated by the UVB eye irradiation. Conversely, the symptoms improved with UVA eye irradiation. The levels of adrenocorticotropic hormone (ACTH), corticotropin-releasing hormone (CRH), urocortin 2, interleukin (IL)-18, IL-6 and histamine in the blood increased after the UVB eye irradiation of DSS-treated mice (UVB/DSS-treated mice). In contrast, the β-endorphin level in the blood of the UVA/DSS-treated mice increased and the levels of urocortin 2, tumor necrosis factor (TNF)-α and histamine decreased. Furthermore, in the colon, the expression of melanocortin-2 receptors (MC2R) increased in the UVB/DSS-treated mice, while the expression of μ-opioid receptors increased in the UVA/DSS-treated mice. When an ACTH inhibitor was administered, UVB eye irradiation caused the deterioration of DSS-treated ulcerative colitis, while the effect of UV eye irradiation disappeared with a μ-opioid receptor antagonist. These results suggested that UV eye irradiation plays an important role in DSS-induced ulcerative colitis.
© 2016 The American Society of Photobiology.

Although trichloroacetic acid (TCA) peeling is widely applied for cosmetic treatment of photodamaged skin, the entire biological mechanisms have yet to be determined. The skin stress response system (SSRS) involves corticotropin-releasing hormone (CRH) and proopiomelanocortin (POMC) products that are locally-generated in response to locally-provided stressors or pro-inflammatory cytokines. This system would restrict tissue damage and restore local homeostasis. To determine the influence of TCA peeling on the SSRS in vitro and in vivo, expressions of POMC, melanocortin receptor 1 (MC1R), CRH and CRH receptor 1 (CRHR1) mRNA were examined by reverse transcription polymerase chain reaction in Pam212 murine keratinocytes, murine plantar and healthy human abdominal skin specimens after TCA treatment. In addition, their protein expressions as well as those of POMC-derived peptides were examined immunohistochemically. After TCA treatment, transient upregulation of POMC and MC1R mRNA expressions was observed in both murine and human skin, as well as in Pam212. Enhanced POMC protein, recovery of once-impaired MC1R protein, and no enhancement of POMC-derived peptide productions were revealed immunohistochemically in both murine and human epidermis. In contrast, neither expression levels of CRH and CRHR1 mRNA nor epidermal protein were enhanced after TCA application in murine and human skin, except for induction of human CRH mRNA expression. These results suggest that TCA activates the SSRS by inducing POMC and MC1R productions of keratinocytes in the CRH-independent manner, and that the biological effects of POMC itself are responsible for the TCA-induced epidermal SSRS activation.
© 2010 Japanese Dermatological Association.