Increased ZAP70 Involves In The Elderly Mice With Dry Skin Pruritus

OBJECTITVE: Dry skin pruritus is common in elderly people.However, the mechanism of dry skin causes pruritus is still unclear. Recent reports show that immune response may involve in dry skin pruritus via regulation of cytokines secretion. Zeta-chain-associated protein kinase 70(ZAP70), as a T-cell receptor, may promote the secretion of nerve growth factor(NGF) and Interleukin 2(IL-2) in dry skin pruritus. This study aimed to detect the alteration of ZAP70 in a mice model with dry skin pruritus.METHOD: C57 BL mice with 5- month and 22- month were used as experimental animal. Young group used 5- month mice and elderly group used 22- month mice. Model with dry skin pruritus was performed as following. Rostral back was treated daily with cutaneous application of acetone /ether(1:1) mixture(AE), water following AE for 5 days, model with dry skin pruritus was completed(AEW). Cotton soaked with physiological saline solution was laid upon 5- month mice and 22- month mice on the shaved area for 60 s as control group. ZAP70 was examined by immunohistochemistry, western-bolt and Real-Time Quantitative PCR.IL-2 and NGF were examined by enzyme linked immunosorbent assay(ELISA).RESULTS: After AEW treated, spontaneous scratching observation of 22- month mice show a significantly increased compared to 5- month mice. The number of spontaneous scratching of elderly group was 218 bouts per hour; the young group was 118 bouts per hour. Western blot analysis of ZAP70 expression is reported that 22- month mice group was1.84±0.09 and 5- month mice was 1.17±0.06. ZAP70 expression in elderly group being significantly higher than young group in skin with dry skin pruritus(P < 0.05). These results were in agreement with Real-Time Quantitative PCR for ZAP70. ELISA data analyze show that IL-2 and NGF secretion in elderly group being significantly higher than young group.CONCLUSION: Our results indicate that increased ZAP70 expression might regulate dry skin pruritus via promote NGF and IL-2secretion in elderly dry skin pruritus.