UVA irradiation of the eye modulates the contact hypersensitivity of the skin and intestines by affecting mast cells in mice

An Inhibitor of Casein Kinase 1ε/δ (PF670462) Prevents the Deterioration of Dextran Sodium Sulfate-induced Ulcerative Colitis Caused by UVB Eye Irradiation

Although we previously reported the exacerbation of dextran sodium sulfate (DSS)-induced ulcerative colitis by ultraviolet (UV) B eye irradiation, we do not yet understand the mechanism behind this phenomenon. In this study, we examined the relationship between the deterioration of DSS-induced ulcerative colitis and clock genes. We induced a mouse model of ulcerative colitis by administering DSS for 5 days, and administered UVB eye irradiation on each day of the DSS treatment period. The DSS-induced ulcerative colitis was deteriorated by the UVB eye irradiation. The levels of Clock, brain and muscle arnt-like protein 1 (Bmal1), reverse orientation c-erb A gene (Rev-Erb)α, RAR-related orphan receptor gamma (RORγt), and interleukin (IL)-17 in the colon were increased by UVB eye irradiation in the DSS-treated mice (UVB/DSS-treated mice). Conversely, the nuclear factor, interleukin 3 regulated (NFIL-3) levels in the colon were lower after UVB eye irradiation. The Casein Kinase 1ε/δ inhibitor (PF670462) administration, which is a Clock/Bmal1 inhibitor (PER2 activator), inhibited the deterioration caused by UVB eye irradiation. These results suggest that the UVB eye irradiation-mediated exacerbation of DSS-induced ulcerative colitis depends on IL-17 produced in response to alterations in clock genes.

Ultraviolet A Eye Irradiation Ameliorates Atopic Dermatitis via p53 and Clock Gene Proteins in NC/Nga Mice

Atopic dermatitis (AD) is a widespread chronic skin condition that severely affects quality of life and can lead to more serious complications. Although ultraviolet (UV)A eye irradiation can exert various effects on the skin, it is unknown whether UVA can affect AD. To investigate potential associations, we used an NC/Nga mouse model of AD to study the effects of UVA eye irradiation. The eyes of mice were irradiated with a UVA dose of 100 kJ m^-2 using a FL20SBLB-A lamp. Our histological data demonstrated that AD symptoms could be ameliorated by UVA eye irradiation. We also observed an increase in the levels of adrenocorticotropic hormone (ACTH), p53 and retinoid X receptor α (RXRα) in mice with UVA-irradiated eyes. In contrast, the levels of thymic stromal lymphopoietin (TSLP), period 2 (PER2) and differentiated embryo chondrocytes 1 (DEC1) protein were decreased in mice treated with UVA irradiation. Furthermore, UVA eye-irradiated mice exhibited reduced DEC1 and RXRα colocalization compared with nonirradiated mice. These results suggested that p53 and various clock gene proteins played important roles in the amelioration of AD symptoms observed after UVA eye irradiation; this technique may have therapeutic applications in AD.

Ultraviolet A eye irradiation ameliorates colon carcinoma induced by azoxymethane and dextran sodium sulfate through β-endorphin and methionine-enkephalin

BACKGROUND

We previously reported that ultraviolet (UV) A eye irradiation reduces the ulcerative colitis induced by dextran sodium sulfate (DSS). This study examined the effects of UVA on colon carcinoma induced by azoxymethane (AOM) and DSS.

METHODS

We irradiated the eyes of ICR mice with UVA at a dose of 110 kJ/m² using an FL20SBLB-A lamp for the experimental period.

RESULTS

In mice treated with these drugs, the symptom of colon carcinoma was reduced by UVA eye irradiation. The levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-α in the blood were increased in AOM + DSS-treated mice; however, those levels were reduced by UVA eye irradiation. The expression of β-endorphin, methionine-enkephalin (OGF), μ-opioid receptor, and opioid growth factor receptor (OGFR) of the colon was increased in the AOM + DSS-treated mice, and these levels were increased further following UVA eye irradiation. When β-endorphin inhibitor was administered, the ameliorative effect of UVA eye irradiation was reduced, and the effect of eye irradiation disappeared entirely following the administration of naltrexone (inhibitor of both opioid receptor and OGFR).

CONCLUSIONS

These results suggested that UVA eye irradiation exerts major effects on AOM + DSS-induced colon carcinoma.

On the role of skin in the regulation of local and systemic steroidogenic activities

The mammalian skin is a heterogeneous organ/tissue covering our body, showing regional variations and endowed with neuroendocrine activities. The latter is represented by its ability to produce and respond to neurotransmitters, neuropeptides, hormones and neurohormones, of which expression and phenotypic activities can be modified by ultraviolet radiation, chemical and physical factors, as well as by cytokines. The neuroendocrine contribution to the responses of skin to stress is served, in part, by local synthesis of all elements of the hypothalamo-pituitary-adrenal axis. Skin with subcutis can also be classified as a steroidogenic tissue because it expresses the enzyme, CYP11A1, which initiates steroid synthesis by converting cholesterol to pregnenolone, as in other steroidogenic tissues. Pregnenolone, or steroidal precursors from the circulation, are further transformed in the skin to corticosteroids or sex hormones. Furthermore, in the skin CYP11A1 acts on 7-dehydrocholesterol with production of 7-dehydropregnolone, which can be further metabolized to other Δ7steroids, which after exposure to UVB undergo photochemical transformation to vitamin D like compounds with a short side chain. Vitamin D and lumisterol, produced in the skin after exposure to UVB, are also metabolized by CYP11A1 to several hydroxyderivatives. Vitamin D hydroxyderivatives generated by action of CYP11A1 are biologically active and are subject to further hydroxylations by CYP27B1, CYP27A1 and CP24A. Establishment of which intermediates are produced in the epidermis in vivo and whether they circulate on the systemic level represent a future research challenge. In summary, skin is a neuroendocrine organ endowed with steroid/secosteroidogenic activities.