Timecourse study of UV radiation effects on skin immune system comparing harmfull vs. daily exposures

CELA, E.M.; LEONI, J.; GONZÁLEZ MAGLIO, D.H.

Los Cocos, Córdoba

Congreso; LXI Reunión Anual de la Sociedad Argentina de Inmunología; 2013

Cutaneous exposure to UV radiation (UVr) induces the production of several mediators by skin cells, both from Epidermis (E) and Dermis (D), involved in inflammation and systemic immune suppression. Crosstalk between E and D can be evaluated only in in vivo models. We aimed to compare effects of a high UV dose (400 mJ/cm2 ?simulating harmful exposure-) vs. repetitive low UV doses (4 times of 20 mJ/cm2 -simulating daily exposure-) on skin immune system.SKH-1 hairless mice were UV-irradiated and sacrificed after 2, 6, 24 and 192 hs, to compare skin histological alterations (H&E), epidermal T Cell percentage (Flow cytometry), epidermal cells? mitochondrial function (DiOC6?MitoSOX-Red probes), gene transcription (RT-PCR) of TNFα, IL6, IL10, VEGFα, CXCL1, CXCL2, CXCL12, TLR2, TLR4, βDefensin14 (βdef14) and Cathelicidin (CAMP) in E and D, and protein expression (ELISA) of TNFα, IL6, IL10, IL1β, CXCL1, MCP1 in E and D.Both UV doses produced changes in epidermal thickness&. Repetitive low UV doses activated mitochondrial function#, increased transcription of VEGFα& and CAMP* (E&D), TNFα*, IL6&, CXCL12&, TLR2#, TLR4* and βdef14& (D), and induced a slight expression of TNFα* and MCP1* (E) and CXCL1* (D). A single high UV dose reduced mitochondrial function& increasing superoxide production#, diminished epidermal T cell percentage#, increased transcription of VEGFα& (E&D), IL-6*, CXCL12*, βdef14# and CAMP* (D), and induced a high production of IL6# (E&D), TNFα&, CXCL1#, MCP1# (E&D), and a slight production of IL10* and IL1β* (E). Abovementioned results significantly differ from control mice: *p<0.05, #p<0.01, &p<0.001.This timecourse study showed changes in skin structure, metabolic cellular function, transcription and expression of several molecules in an in vivo model using two different UVr doses. A single high UV exposure caused tissue damage and marked inflammatory environment while repetitive low UV exposures induced tissue adaptation, with low inflammation and a state of immune alert.