Study on Improvement Effects of Qishenlian Eczema Cream on the Atopic Dermatitis Model Guinea Pigs / 中国药房

OBJECTIVE： To investigate the improvement effects of Qishenlian eczema cream on the atopic dermatitis （AD） model guinea pigs， and to investigate its possible mechanism. METHODS： Female guinea pigs were randomly divided into normal control group， model control group， matrix control group （Qishenlian eczema cream matrix， 1 g/kg）， Qishenlian eczema cream low-dose， medium-dose and high-dose groups （0.5， 1， 2 g/kg） and Hydrocortisone butyrate cream group （0.5 g/kg）， with 10 guinea pigs in each group. Using ovalbumin as antigen， the skin allergy of guinea pigs was stimulated to induce AD model. Forty-eight hours after the last excitation， guinea pigs were smeared with normal saline in normal control group and model control group， while those were smeared with Qishenlian eczema cream matrix in matrix control group， and administration groups were treated with relevant medicine， twice a day， for consecutive 14 d. The scores of erythema， edema and scratch before and after administration were recorded in each group. The morphological characteristics of skin were observed by HE staining. TUNEL method was used to detect the apoptosis of keratinocytes in skin tissue. The level of IFN-γ in skin lesions was detected by ELISA. RESULTS： Compared with normal control group， inflammatory cell infiltration， hyperkeratosis of epidermis and thickening of spinous layer were observed in skin tissue of guinea pigs in model control group and matrix control group； the scores of erythema， edema and scratch and their total score， the level of IFN-γ in skin tissue were increased significantly； the apoptosis number of keratinocytes was decreased significantly （P＜0.01）. Compared with model control group and matrix control group， above symptoms of medication groups were relieved to different extents； the scores of erythema， edema and scratch and their total score after medication in medication groups， the level of IFN-γ in skin tissue in Qishenlian eczema cream medium-dose and high-dose groups and Hydrocortisone butyrate cream group were decreased significantly， and above scores in medication groups were significantly lower than before medication （P＜0.05 or P＜0.01）； the apoptosis number of keratinocytes was increased significantly in medication groups （P＜0.05 or P＜0.01）. CONCLUSIONS： Qishenlian eczema cream has certain improvement effect on AD model guinea pigs， the mechanism of which may be associated with promoting the keratinocyte apoptosis， reducing the level of INF-γ in skin tissue.

IL-1 Receptor Antagonist Reduced Chemical-Induced Keratinocyte Apoptosis through Antagonism to IL-1α/IL-1β

Extracellular interleukin 1 alpha (IL-1α) released from keratinocytes is one of the endpoints for in vitro assessments of skin irritancy. Although cells dying via primary skin irritation undergo apoptosis as well as necrosis, IL-1α is not released in apoptotic cells. On the other hand, active secretion has been identified in interleukin-1 receptor antagonist (IL-1ra), which was discovered to be a common, upregulated, differentially-expressed gene in a microarray analysis performed with keratinocytes treated using cytotoxic doses of chemicals. This study examined whether and how IL-1ra, particularly extracellularly released IL-1ra, was involved in chemically-induced keratinocyte cytotoxicity and skin irritation. Primary cultured normal adult skin keratinocytes were treated with cytotoxic doses of chemicals (hydroquinone, retinoic acid, sodium lauryl sulfate, or urshiol) with or without recombinant IL-1ra treatment. Mouse skin was administered irritant concentrations of hydroquinone or retinoic acid. IL-1ra (mRNA and/or intracellular/extracellularly released protein) levels increased in the chemically treated cultured keratinocytes with IL-1α and IL-1β mRNAs and in the chemically exposed epidermis of the mouse skin. Recombinant IL-1ra treatment significantly reduced the chemically-induced apoptotic death and intracellular/extracellularly released IL-1α and IL-1β in keratinocytes. Collectively, extracellular IL-1ra released from keratinocytes could be a compensatory mechanism to reduce the chemically-induced keratinocyte apoptosis by antagonism to IL-1α and IL-1β, suggesting potential applications to predict skin irritation.

Role of Keratinocytes in the Development of Vitiligo

Vitiligo is an acquired depigmentary disorder of the skin that results from the loss of functioning epidermal melanocytes. Most studies on vitiligo have concentrated on the abnormality of melanocytes rather than the abnormality of keratinocytes; however, epidermal melanocytes form a functional and structural unit with neighboring keratinocytes. In fact, direct cell-to cell contact stimulates in vitro proliferation of melanocytes, and growth factors produced by adjacent keratinocytes regulate the proliferation and differentiation of melanocytes. The potential role of keratinocyte-derived cytokines has also been presented. We focused on the structural changes in vitiliginous keratinocytes, which may result in loss of melanocytes, to examine the pathomechanism of vitiligo. The results of a comparison between depigmented and normally pigmented epidermis in patients with vitiligo showed that the keratinocytes in the depigmented epidermis were more vulnerable to apoptosis. Impaired Phosphatidylinositol 3-kinase (PI3K)/serine/threonine protein kinase (Akt) activation followed by reduced nuclear factor-kappaB activation under increased tumor necrosis factor-alpha levels was demonstrated as a mechanism for keratinocyte apoptosis. The role of aquaporin 3 in keratinocyte apoptosis was addressed based on the relationship between the PI3K/AKT pathway and the E-cadherin-catenin complex. Apoptotic keratinocytes induced a lower expression of keratinocyte-derived factors, including stem cell factor, in depigmented epidermis, resulting in passive melanocyte death.