Inhibition of citrate transport reduces HIF-1α/GABA-T-mediated succinate accumulation in macrophages: The role of astragaloside IV in ischemic stroke.

Background: The occurrence of ischemic stroke is closely associated with the inflammatory infiltration of peripheral monocytes/macrophages, and the inflammatory activation of macrophages is often affected by metabolic reprogramming. The Slc25a1 regulates mitochondrial citrate transport and has been shown to affect cell proliferation and migration in cancer. Astragaloside IV exhibits significant anti-inflammatory activity and improves ischemic stroke, but its regulatory effect on macrophage metabolic reprogramming has not been elucidated.

Objectives: This study aims to explore the effect of astragaloside IV on ischemic stroke injury from the perspective of Slc25a1-mediated cellular metabolic reprogramming.

Methods: A total of 170 mice were used to establish the middle cerebral artery occlusion (MCAO) model. The therapeutic effect of astragaloside IV was evaluated by neurobehavioral scores and infarct volume, with its impact further verified through the depletion of peripheral macrophages. The modulation of Slc25a1 by astragaloside IV and its influence on macrophages were investigated in mouse bone marrow-derived macrophages (BMDMs) and peripheral blood mononuclear cell-derived macrophages (PBMC-derived macrophages).

Results: Astragaloside IV significantly mitigated neurological impairment and reduced cerebral infarction volume in MCAO mice by inhibition of peripheral monocytes/macrophage inflammatory infiltration. In activated BMDMs and PBMC-derived macrophages, astragaloside IV interacted with Slc25a1, attenuated citrate transport, maintained mitochondrial function, therefore enhancing the shift from the M1- to M2-like macrophages. Mechanistically, astragaloside IV inhibited the transcriptional regulation of HIF-1α on GABA-T via citate-mediated histone H3 and H4 deacetylation and promoted the resumption of the broken TCA cycle and mitochondrial OXPHOS in macrophages.

Conclusions: Our study unveiled a therapeutic strategy for ischemic stroke by intervening in the inflammatory infiltration of peripheral monocytes/macrophages. Astragaloside IV, by binding to the mitochondrial citrate transporter Slc25a1, maintained the homeostasis of the TCA cycle and mitochondrial function, ultimately blocking the inflammation of peripheral macrophages to ameliorate ischemic stroke damage. This discovery provides data support for expanding the clinical application of astragaloside IV and offers research insights into the external treatment of encephalopathy.