Background: dl-Malic acid (dl-M) is used widely in cosmetic formulations as a pH-adjuster or as a preservative. dl-M is used as an exfoliator in the form of α-hydroxy acids. However, the role of dl-M in skin diseases (including atopic dermatitis (AD)) has not been studied deeply. We wished to reveal the effect of dl-M on AD induced by 2,4-dinitrochlorobenzene (DNCB) in Balb/c mice.Methods: The thickness and immune-cell infiltration into the dermis and epidermis were evaluated. Moreover, serum levels of cytokines, as well as expression of mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) in tissue were measured in AD mice. We also studied the effect of dl-M on inflammatory mediators in a human keratinocyte (HaCaT) cell line. Results: The dl-M (high) group improved skin condition compared with the DNCB-treated group. The dl-M (high) group inhibited phosphorylation of MAPK and NF-κB in skin tissue. dl-M reduced serum levels of interleukin-4 and IgE. Finally, dl-M decreased the expression of thymus and activation-regulated chemokine, monocyte chemoattractant protein-1 and intercellular cell adhesion molecule induced by interferon-gamma/tumor necrosis factor-α in HaCaT cells. Discussion: These results suggest that dl-M can improve the skin conditions of AD mice.

中文翻译：

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dl-苹果酸作为α-羟基酸的成分：在体外和体内对2,4-二硝基氯苯诱发的特应性皮炎样皮肤损伤中炎症的影响。

背景：dl-苹果酸（dl-M）在化妆品配方中广泛用作pH调节剂或防腐剂。dl-M以α-羟基酸的形式用作去角质剂。然而，尚未深入研究dl-M在皮肤疾病（包括特应性皮炎（AD））中的作用。我们希望揭示dl-M对Balb / c小鼠2,4-二硝基氯苯（DNCB）诱导的AD的影响。方法：评估厚度和免疫细胞浸入真皮和表皮的能力。此外，在AD小鼠中测量了血清中细胞因子的水平以及组织中丝裂原活化蛋白激酶（MAPK）和核因子-κB（NF-κB）的表达。我们还研究了dl-M对人角质形成细胞（HaCaT）细胞系中炎症介质的影响。结果：与DNCB治疗组相比，dl-M（高）组改善了皮肤状况。dl-M（高）基团抑制皮肤组织中MAPK和NF-κB的磷酸化。dl-M降低了白介素4和IgE的血清水平。最后，dl-M降低了HaCaT细胞中γ-干扰素/肿瘤坏死因子-α诱导的胸腺表达和激活调节的趋化因子，单核细胞趋化蛋白-1和细胞间粘附分子。讨论：这些结果表明，dl-M可以改善AD小鼠的皮肤状况。