Modulation of ultraviolet-induced hyperalgesia and cytokine upregulation by interleukins 10 and 13

1. Exposure to midrange ultraviolet radiation (UVB) is known to produce skin inflammation similar to sunburn. The aim of this study was to characterize the hyperalgesia and cytokine upregulation induced by UVB and their modulation by antiinflammatory cytokines. 2. Acute exposure of the dorsal skin of mice to UVB (200, 250 and 300 mJ cm(2)) resulted in a dose-dependent decrease in the latencies of the hot plate and tail flick tests, without evident signs of skin lesions. 3. The observed hyperalgesia displayed a biphasic temporal evolution with an acute phase (3 - 6 h) and a late (48 - 96 h) phase. 4. Exposure to UVB (300 mJ cm(2)) elicited significant upregulation of interleukin (IL)-1 beta, tumour necrosis factor (TNF)-alpha and nerve growth factor (NGF), determined by ELISA in the exposed skin. This upregulation was more important during the acute phase of hyperalgesia. 5. Daily treatment of mice, with i.p. injections of either IL-10 or IL-13 (1.5, 7.5 and 15 ng in 100 microl saline) produced a dose-dependent attenuation of the UVB-induced hyperalgesia. 6. Treatment with the highest doses of either IL-10 or IL-13, produced significant attenuation of the levels of the cytokines and NGF by UVB, with relatively more pronounced effects by IL-13. 7. Acute exposure to moderate amounts of UVB results in a systemic hyperalgesia related to the upregulation of cytokine and NGF levels, since both were prevented by treatment with antiinflammatory cytokines.