Artificial human skin: cytokine, prostaglandin, Hsp70 and histological responses to heat exposure

Abstract

Artificial human skin, Skin 2™ (keratinocytes and fibroblasts) and EpiDerm™ (keratinocytes), was used to determine heat-induced release/accumulation of mediators of injury and repair. Skin 2 was exposed to 37 or 41–45°C for 90 min, followed by 37°C for 22.5 h. Media were analyzed for interleukin-1α (IL-1α), prostaglandin-E 2 (PGE 2), thromboxane-B 2 (TxB 2) and nuclear matrix apparatus protein (NMAP, viability). Specimens were taken for microscopy. Media and lysates from Skin 2 and EpiDerm (37 and 45°C) were analyzed for IL-1α, its soluble receptor (sIL-1RII), receptor antagonist (IL-1Ra), interleukin-6 (IL-6) and heat shock protein-70A (lysates only). Significant release of IL-1α and PGE 2 was detected only above 43°C, where viability deteriorated and histological damage (especially to keratinocytes) was observed. With both skin products, sIL-1RII release was heat-depressed. IL-1α and IL-1Ra were elevated in media and IL-1Ra appeared to lower the bioactivity of IL-1α. Heat depressed IL-6 release from Skin 2 fibroblasts. IL-6 production and release were negligible with EpiDerm. Heat increased Hsp-70A in both products. We conclude keratinocytes and fibroblasts are not primary cytokine and prostaglandin sources in heatstroke (<44°C) but could be in evaporative cooling failure, focal hot spots, or systemic responses. Levels of IL-1Ra, PGE 2 and Hsp70A may be important markers of cell status.