Lauritzen Knut Husø, Yang Kuan, Frisk Michael, Louwe Mieke C, Olsen Maria Belland, Ziegler Mathias, Louch William E, Halvorsen Bente, Aukrust Pål, Yndestad Arne, Sandanger Øystein
Research Institute of Internal Medicine, Oslo University Hospital, Rikshospitalet and University of Oslo, Oslo, Norway.
Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.
Front Immunol. 2025 Jan 7;15:1497984. doi: 10.3389/fimmu.2024.1497984. eCollection 2024.
CD38, a regulator of intracellular calcium signalling, is highly expressed in immune cells. Mice lacking CD38 are very susceptible to acute bacterial infections, implicating CD38 in innate immune responses. The effects of CD38 inhibition on NLRP3 inflammasome activation in human primary monocytes and monocyte-derived macrophages have not been investigated. Apigenin is a naturally occurring flavonoid known to inhibit CD38. However, apigenin has also been proposed to inhibit the extracellular ATP receptor P2XR7, an upstream activator of NLRP3. In this study we aimed to investigate whether apigenin attenuates NLRP3 inflammasome activation in human monocytes and monocyte-derived macrophages through CD38 inhibition.
LPS-primed human monocytes and monocyte-derived macrophages were treated with apigenin, the CD38 inhibitor 78c, antagonists of CD38 second messengers (8-br-ADPR and 8-br-cADPR) or the ATP hydrolase, apyrase, prior to NLRP3 activation with ATP, monosodium urate crystals (MSU) or nigericin. IL-1β and TNF secretion and mRNA expression, as well as N-terminal gasdermin-D formation were quantified. Ca mobilization was determined by live confocal microscopy. NLRP3 activity was also compared in WT and CD38 mouse bone marrow-derived macrophages (BMDMs) with and without CD38 inhibitors.
Apigenin significantly inhibited IL-1β release from LPS-primed monocytes and macrophages activated with ATP, MSU, or nigericin. CD38 inhibition with 78c also attenuated NLRP3-dependent IL-1β release. Apigenin was a potent inhibitor of Ca flux from the endoplasmic reticulum to the cytosol in human monocyte-derived macrophages. Apyrase attenuated IL-1β release induced by ATP or MSU, but not by nigericin. However, the NLRP3 inflammasome is not compromised in CD38 bone marrow-derived macrophages compared to corresponding WT cells, and apigenin moderated IL-1β release in both genotypes.
Our data support that apigenin attenuates NLRP3 activation independently of CD38. Our results also suggest that MSU crystals activate NLRP3 through autocrine or paracrine ATP signalling.
CD38是一种细胞内钙信号调节因子，在免疫细胞中高度表达。缺乏CD38的小鼠极易受到急性细菌感染，这表明CD38参与了先天免疫反应。CD38抑制对人原代单核细胞和单核细胞衍生巨噬细胞中NLRP3炎性小体激活的影响尚未得到研究。芹菜素是一种已知可抑制CD38的天然黄酮类化合物。然而，也有人提出芹菜素可抑制细胞外ATP受体P2XR7，后者是NLRP3的上游激活剂。在本研究中，我们旨在探讨芹菜素是否通过抑制CD38来减弱人单核细胞和单核细胞衍生巨噬细胞中NLRP3炎性小体的激活。
在用ATP、尿酸单钠晶体（MSU）或尼日利亚菌素激活NLRP3之前，用芹菜素、CD38抑制剂78c、CD38第二信使拮抗剂（8-溴-ADPR和8-溴-cADPR）或ATP水解酶、腺苷三磷酸双磷酸酶处理经脂多糖预处理的人单核细胞和单核细胞衍生巨噬细胞。对白细胞介素-1β和肿瘤坏死因子的分泌、mRNA表达以及N端gasdermin-D的形成进行定量。通过实时共聚焦显微镜测定钙动员。还比较了野生型和CD38基因敲除小鼠骨髓来源巨噬细胞（BMDM）在有无CD38抑制剂情况下的NLRP3活性。
芹菜素显著抑制了经脂多糖预处理的单核细胞和巨噬细胞在用ATP、MSU或尼日利亚菌素激活后白细胞介素-1β的释放。用78c抑制CD38也减弱了NLRP3依赖性白细胞介素-1β的释放。芹菜素是人类单核细胞衍生巨噬细胞中从内质网到细胞质的钙通量的有效抑制剂。腺苷三磷酸双磷酸酶减弱了由ATP或MSU诱导的白细胞介素-1β释放，但不能减弱由尼日利亚菌素诱导的释放。然而，与相应的野生型细胞相比，CD38基因敲除的骨髓来源巨噬细胞中的NLRP3炎性小体并未受损，并且芹菜素在两种基因型中均能调节白细胞介素-1β的释放。
我们的数据支持芹菜素可独立于CD38减弱NLRP3的激活。我们的结果还表明，MSU晶体通过自分泌或旁分泌ATP信号激活NLRP3。
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