Hyperthermia to normal human skin in vivo upregulates heat shock proteins 27, 60, 72i and 90

This study was performed to test the hypothesis that expression of heat shock proteins (HSPs) exhibits a spatially selective response within intact human skin following in vivo exposure to thermal stress. This response is believed to protect cells and tissues from further damage. Using Western blotting and immunohistochemistry, we studied the expression of a range of HSPs in normal human skin of 5 subjects prior to and following heating in vivo. The skin was heated to 41 ± 0.5°C for 1 h and biopsies were taken at 4, 8 and 24 h and from control, untreated skin. HSPs 27, 60, 72i, 90, 110 and heat shock constitutive (HSC)70 were expressed in normal skin, but the extent and distribution of these HSPs showed considerable variation. HSP27, 60 and 72i were found predominantly in the epidermis, whereas HSC70 showed weak epidermal staining but strong dermal expression. Heating the skin in vivo resulted in an increased skin content of HSP27, 60, 72i and 90, with maximal increase at 24 h following hyperthermia, while the skin content of HSC70 and HSP110 were unchanged. Significant increases in the content of HSP72i and HSP90 had occurred by 4 h following hyperthermia, with a mean ± SEM of 206 ± 50% and 197 ± 38% of the control, untreated values, respectively (p <0.05). These findings indicate the complexity of HSP dynamics in human skin, and suggest that healing within the experimental range may protect the skin from further stresses for at least 24 h.