Effects of skin UV light exposure on the immune response against a pathogen and a vaccine

CELA EM; CAMPO V; GONZÁLEZ C; FRIEDRICH AD; LEDO C; PAZ ML; GOMEZ M; LEONI J; GONZÁLEZ MAGLIO DH

Aveiro

Congreso; European Society for Photobiology 2015 Congress; 2015

European Society for Photobiology

It is well known that ultraviolet radiation (UVr) leads to immunosuppression, inhibiting CHS reactions. However, the way UVr modulates immune responses against microorganisms has been poorly explored. Considering that Staphylococcus aureus (SA) causes skin infections and this organ is the main target of UVr, our first aim was to evaluate if UVr can modulate the host response to SA infection, using in vitro and in vivo models. Besides SA infection, skin is also a target for vaccination. Our second objective was to evaluate the effect of UVr on BCG vaccination in vivo. For in vitro experiments we used UVr-exposed HaCaT cells, challenged with heat killed SA (hkSA) and purified lipoteichoic acid (LTA). For both in vivo experiments (SA and BCG), we compared 2 types of exposures of SKH:1 mice: a single high UV dose (shUVd - 400 mJ/cm2), as a harmful exposure vs. repetitive low UV doses (rlUVD - 4 consecutive days, 20 mJ/cm2), simulating daily exposures. Previously, we have found that shUVd promotes skin inflammation while it diminishes CHS reaction and antibody production, in contrast to rlUVd that does not induce inflammation and increases CHS response and antibody production. HaCaT cells were irradiated with 10, 25 and 50 mJ/cm2 and immediately challenged with hkSA, LTA or LPS as control. SKH:1 mice were irradiated and 24h later were subcutaneously infected with SA strain LAC (1x107 CFU) or intradermally vaccinated with BCG (1x104 CFU). Non-irradiated cells and mice were used as control (C). In vitro hkSA and LTA challenge of irradiated HaCaT cells promotes greater inflammatory cytokines production (TNF-alpha and IL-6) than E. coli LPS stimuli or the corresponding non-irradiated challenged cells.In vivo SA infection produced no differences in weight loss, abscess size and bacterial counts between control and irradiated mice. shUVd mice did not show differences in the dissemination of bacteria or in spleen cells proliferative response, whereas they produced higher titers of specific IgG and IgM (p