Following activation, macrophages undergo extensive metabolic rewiring^1,2. Production of itaconate through the inducible enzyme IRG1 is a key hallmark of this process³. Itaconate inhibits succinate dehydrogenase^4,5, has electrophilic properties⁶ and is associated with a change in cytokine production⁴. Here, we compare the metabolic, electrophilic and immunologic profiles of macrophages treated with unmodified itaconate and a panel of commonly used itaconate derivatives to examine its role. Using wild-type and Irg1^−/− macrophages, we show that neither dimethyl itaconate, 4-octyl itaconate nor 4-monoethyl itaconate are converted to intracellular itaconate, while exogenous itaconic acid readily enters macrophages. We find that only dimethyl itaconate and 4-octyl itaconate induce a strong electrophilic stress response, in contrast to itaconate and 4-monoethyl itaconate. This correlates with their immunosuppressive phenotype: dimethyl itaconate and 4-octyl itaconate inhibited IκBζ and pro-interleukin (IL)-1β induction, as well as IL-6, IL-10 and interferon-β secretion, in an NRF2-independent manner. In contrast, itaconate treatment suppressed IL-1β secretion but not pro-IL-1β levels and, surprisingly, strongly enhanced lipopolysaccharide-induced interferon-β secretion. Consistently, Irg1^−/− macrophages produced lower levels of interferon and reduced transcriptional activation of this pathway. Our work establishes itaconate as an immunoregulatory, rather than strictly immunosuppressive, metabolite and highlights the importance of using unmodified itaconate in future studies.

激活后，巨噬细胞经历广泛的代谢重新布线^1,2。通过可诱导酶IRG1产生衣康酸酯是该过程的关键特征³。衣康酸酯抑制琥珀酸脱氢酶^4,5，具有亲电特性^6，并与细胞因子产生的变化有关⁴。在这里，我们比较未经修饰的衣康酸酯和一组常用的衣康酸酯衍生物处理的巨噬细胞的代谢，亲电和免疫学特征，以检查其作用。使用野生型和Irg1 ^{- / -}巨噬细胞，我们显示衣康酸二甲酯，衣康酸4-辛基酯或衣康酸4-单乙酯均未转化为细胞内衣康酸，而外源衣康酸则容易进入巨噬细胞。我们发现只有衣康酸二甲酯和衣康酸4-辛酯与衣康酸酯和衣康酸4-单乙酯相比，能诱导强烈的亲电应力响应。这与其免疫抑制表型相关：衣康酸二甲酯和衣康酸4-辛基酯以独立于NRF2的方式抑制IκBζ和促白介素（IL）-1β的诱导，以及IL-6，IL-10和干扰素-β的分泌。相反，衣康酸酯治疗抑制IL-1β分泌，但不抑制IL-1β原水平，并且令人惊讶地，强烈增强脂多糖诱导的干扰素-β分泌。一致地，Irg1 ^-/-巨噬细胞产生较低水平的干扰素并降低该途径的转录激活。我们的工作将衣康酸酯确立为一种免疫调节物质，而不是严格的免疫抑制代谢物，并强调了在未来的研究中使用未经修饰的衣康酸酯的重要性。