The immune system is known to have a circadian rhythm; however, how circadian rhythms might affect immune homeostasis and physiology more broadly is unclear. A new paper now provides evidence that γδ T cells (a type of innate T cell) produce IL-17 in a rhythmic fashion, which is essential for de novo lipogenesis in adipose tissue and influences whole-body homeostasis.

To confirm that IL-17A and IL-17F are expressed in a circadian rhythm, the researchers used flow cytometry to analyse γδ T cells from the adipose tissue of mice, which showed that the expression of the cytokines was regulated by the molecular clock. In mice under homeostatic conditions, IL-17A levels peaked during the night (the active phase). “Using a small molecule enhancer (SR9009) of the molecular clock and genetic models (Arntl^ΔVav1 (also known as Bma1) and Arntl^ΔIl7r) to suppress the molecular clock, in collaboration with Henrique Veiga Fernandez’s laboratory in Lisbon, we found that clock genes control IL-17 production by γδ T cells in adipose tissue,” add Lynch and Douglas.

众所周知，免疫系统具有昼夜节律;然而，昼夜节律如何更广泛地影响免疫稳态和生理学尚不清楚。现在一篇新论文提供了证据表明 γδ T 细胞（一种先天性 T 细胞）以有节奏的方式产生 IL-17，这对于脂肪组织中的从头脂肪生成至关重要，并影响全身稳态。

为了确认 IL-17A 和 IL-17F 以昼夜节律表达，研究人员使用流式细胞术分析了来自小鼠脂肪组织的 γδ T 细胞，结果表明细胞因子的表达受分子钟调节。在稳态条件下的小鼠中，IL-17A 水平在夜间（活性期）达到峰值。“使用分子钟和遗传模型（Arntl^ΔVav1（也称为 Bma1）和 Arntl^ΔIl7r）的小分子增强子 （SR9009） 来抑制分子钟，与里斯本的 Henrique Veiga Fernandez 实验室合作，我们发现时钟基因控制脂肪组织中 γδ T 细胞产生 IL-17，”Lynch 和 Douglas 补充道。