Dietary histidine increases mouse skin urocanic acid levels and enhances UVB-induced immune suppression of contact hypersensitivity.
Dietary histidine increases mouse skin urocanic acid levels and enhances UVB-induced immune suppression of contact hypersensitivity.
复制标题
膳食组氨酸可增加小鼠皮肤尿刊酸水平，并增强 UVB 诱导的接触性超敏反应的免疫抑制。
DOI：
10.1111/j.1751-1097.1991.tb03653.x
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发表时间：
1991
影响因子：
3.3
通讯作者：
DeFabo,EC
中科院分区：
文献类型：
--
作者：
Reilly,SK;DeFabo,EC
尿刊酸 (UCA) 主要以反式异构体形式存在于哺乳动物皮肤中，并在吸收 UVB 后光致异构化为顺式 UCA。我们之前的研究表明，UCA 的光异构化是 UVB 诱导的细胞介导免疫抑制（tUCA → cUCA → 免疫抑制）的起始事件。本研究的目的是验证 UCA 在 UV 诱导的 BALB/c 小鼠接触性超敏反应 (CHS) 免疫抑制中的作用。由于 UCA 是氨基酸 L-组氨酸的代谢产物，我们推断饮食中组氨酸水平的增加应该会提高皮肤 tUCA 水平。如果皮肤 tUCA 是用于免疫抑制的 UVB 光感受器，那么这种增加应该会增强紫外线诱导的 CHS 抑制。对喂食富含组氨酸的饮食 (10%) 的 BALB/c 小鼠的皮肤进行 HPLC 分析表明，这些动物中 UCA 的总量明显高于喂食正常饮食的小鼠。此外，在相同 UVB 剂量下，4.8 kJ/m2 UVB 诱导的对照 fad 小鼠中 CHS 抑制水平分别为 3% 和 49%，在组氨酸喂养的动物中分别显着增加至 21% 和 71%。这些发现为免疫抑制的 UCA 模型提供了额外的支持，并提供了第一个证据，证明膳食成分 L-组氨酸可以增强紫外线诱导的免疫抑制。
Urocanic Acid (UCA) exists in mammalian skin primarily as the trans isomer and is photoisomerized to cis UCA upon UVB absorption. Our previous studies indicated that the photoiaomerization of UCA is the initiating event in UVB‐induced suppression of cell‐mediated immunity (tUCA → cUCA → immune suppression). The purpose of this study was to verify the role of UCA in UV‐induced immune suppression of contact hypersensitivity (CHS) in BALB/c mice. Since UCA is a metabolite of the amino acid L‐histidine, we reasoned that increased dietary levels of histidine should raise skin tUCA levels. If skin tUCA is the UVB photoreceptor for immune suppression, this increase should enhance UV‐induced suppression of CHS. HPLC analysis of skin from BALB/c mice given a histidine‐rich diet (10%) showed that the total amount of UCA is significantly higher in these animals than in mice fed a normal diet. Further, levels of suppression of CHS of 3% and 49% in control fad mice, induced by 4.8 and 7.2 kJ/m2 UVB were significantly increased to 21% and 71% respectively in histidine‐fed animals at these same UVB doses. These findings provide additional support for the UCA model for immune suppression, and provide the first evidence that UV‐induced immune suppression can be enhanced by a dietary component, L‐histidine.