Mank Madeleine M, Zoller Kaitlyn A, Fastiggi V Amanda, Ather Jennifer L, Poynter Matthew E
Department of Medicine, Division of Pulmonary Disease and Critical Care, University of Vermont, and The Vermont Lung Center, Burlington, VT, 05405, USA.
Cellular, Molecular, and Biomedical Sciences Doctoral Program, University of Vermont, Burlington, VT, 05405, USA.
bioRxiv. 2025 May 7:2025.05.01.650510. doi: 10.1101/2025.05.01.650510.
NLRP3 inflammasome activation induces the cleavage and secretion of IL-1β and IL-18, and causes pyroptosis. Generated during times of energetic crisis (, caloric insufficiency), the ketone body β-hydroxybutyrate (BHB) has been reported to inhibit NLRP3 inflammasome activation. However, the conditions under which BHB exerts this activity and whether other short-chain carboxylic acids (SCCAs) share this effect are unexplored. Since BHB is often produced in high abundance endogenously accompanied by metabolic acidosis, we aimed to examine the pH-dependence for the ability of BHB and similar molecules to inhibit NLRP3 inflammasome activation and to test receptors conferring these effects. Whereas β-hydroxybutyric acid (BHBA) enantiomers function equivalently to dose-dependently inhibit NLRP3 inflammasome-induced IL-1β secretion, sodium-β-hydroxybutyrate (NaBHB) and NaOH-neutralized BHBA do not inhibit NLRP3 inflammasome activation. Acidifying the pH of the NaBHB stock solution or the media in which cells are exposed to NaBHB, or allowing the cells to endogenously acidify their media, enables NaBHB to inhibit NLRP3 inflammasome activation. Several other SCCAs also inhibit NLRP3 inflammasome activation in a pH-dependent manner and prevent pyroptotic cell death. Finally, Free Fatty Acid Receptor 3 (GPR41/FFAR3) activation phenocopies and augments the NLRP3 inflammasome-inhibiting effects of BHBA. In conclusion, acidification licenses the ability of BHB and related SCCAs to inhibit NLRP3 inflammasome activation, in part through GPR41/FFAR3, thereby expanding the repertoire of metabolites capable of modulating this important pro-inflammatory pathway during times of energetic crisis and optimizing conditions for the potential use of ketone bodies as anti-inflammatories.
NLRP3炎性小体激活会诱导白细胞介素-1β（IL-1β）和白细胞介素-18（IL-18）的裂解与分泌，并引发细胞焦亡。据报道，在能量危机（如热量不足）期间产生的酮体β-羟基丁酸（BHB）可抑制NLRP3炎性小体激活。然而，BHB发挥这种活性的条件以及其他短链羧酸（SCCA）是否具有相同作用尚未得到探究。由于BHB通常在体内大量产生并伴有代谢性酸中毒，我们旨在研究BHB及类似分子抑制NLRP3炎性小体激活能力的pH依赖性，并测试介导这些作用的受体。虽然β-羟基丁酸（BHBA）对映体在剂量依赖性抑制NLRP3炎性小体诱导的IL-1β分泌方面具有同等作用，但β-羟基丁酸钠（NaBHB）和用氢氧化钠中和的BHBA并不抑制NLRP3炎性小体激活。将NaBHB储备溶液或细胞暴露于NaBHB的培养基的pH值酸化，或使细胞内源性地酸化其培养基，可使NaBHB抑制NLRP3炎性小体激活。其他几种SCCA也以pH依赖性方式抑制NLRP3炎性小体激活，并防止细胞焦亡性死亡。最后，游离脂肪酸受体3（GPR41/FFAR3）激活模拟并增强了BHBA对NLRP3炎性小体的抑制作用。总之，酸化赋予了BHB和相关SCCA抑制NLRP3炎性小体激活的能力，部分是通过GPR41/FFAR3实现的，从而扩大了在能量危机期间能够调节这一重要促炎途径的代谢物种类，并优化了酮体作为抗炎剂潜在用途的条件。
