CONICET | Buscador de Institutos y Recursos Humanos

Skin UV exposure induces both a systemic immunesuppression and Vitamin D synthesis, which in turns promotes transcription of immune mediators such as antimicrobial peptides and TLR-2. SKH-1 hairless mice were irradiated with repetitive low UV doses (4 times of 20 mJ/cm2 -simulating daily exposure-) or a single high dose (400 mJ/cm2 ?simulating harmful exposure-) to compare their cellular as well as immune effects, 1 and 8 days post-UV. Both UV doses led to an increase in epidermal thickness& (H&E), but only 4x20 activated mitochondrial function# (DiOC6+ cells) while 1x400 produced the opposite effect&, with the consequent increment in superoxide production# (MitoSOX+ cells), by flow cytometry. Inflammatory mediators (IL-6 and TNF-α) were increased only in 1x400, in dermis& and epidermis& extracts, assayed by ELISA. Epidermal T cell percentage (CD3+ cells) was markedly decreased in 1x400# (flow cytometry); accordingly, epidermal transcription of CXCL-12 was also decreased&, but in all mice groups& (RT-PCR). Both UV doses induced an increment in VEGF transcription, in dermis and epidermis#, but none of them had effects on the transcription of TLR-2 and TLR-4, in both tissues (RT-PCR), or in the 25-OH-Vit D serum levels (RIA). Finally, a tetanus toxoid (TT) challenge was performed for each UV-dose 1 or 8d after irradiation and serum antibodies were titrated. Anti-TT specific total IgG# and IgG3# were increased 1d post-4x20 (3.4 and 3.5 fold), while anti-TT IgG1& and IgG2b* were decreased 1d post-1x400 (3.0 and 4.6 fold). Immunizations performed 8d after-UV did not have effects on specific antibodies titre, in neither group. All differences are expressed vs non-irradiated control mice: *p

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