Caratis Fionä, Karaszewski Bartosz, Klejbor Ilona, Furihata Tomomi, Rutkowska Aleksandra
Department of Anatomy and Neurobiology, Medical University of Gdansk, Gdansk, Poland.
Department of Adult Neurology, Medical University of Gdansk & University Clinical Center, Gdansk, Poland.
PLoS One. 2025 Feb 25;20(2):e0318822. doi: 10.1371/journal.pone.0318822. eCollection 2025.
The endogenous ligand for the EBI2 receptor, oxysterol 7α,25OHC, crucial for immune responses, is finely regulated by CH25H, CYP7B1 and HSD3B7 enzymes. Lymphoid stromal cells and follicular dendritic cells within T cell follicles maintain a gradient of 7α,25OHC, with stromal cells increasing and dendritic cells decreasing its concentration. This gradient is pivotal for proper B cell positioning in lymphoid tissue. In the animal model of multiple sclerosis, the experimental autoimmune encephalomyelitis, the levels of 7α,25OHC rapidly increase in the central nervous system driving the migration of EBI2 expressing immune cells through the blood-brain barrier (BBB). To explore if blood vessel cells in the brain express these enzymes, we examined normal mouse brain microvessels and studied changes in their expression during inflammation. Ebi2 was abundantly expressed in endothelial cells, pericytes/smooth muscle cells, and astrocytic endfeet. Ch25h, Cyp7b1, and Hsd3b7 were variably detected in each cell type, suggesting their active involvement in oxysterol 7α,25OHC synthesis and gradient maintenance under normal conditions. Significant species-specific differences emerged in EBI2 and the enzyme levels between mouse and human BBB-forming cells. Under acute inflammatory conditions, Ebi2 and synthesizing enzyme modulation occurred in the brain, with the magnitude and direction of change based on the enzyme. Lastly, in an in vitro astrocyte migration model, CYP7B1 inhibitor clotrimazole, as well as EBI2 antagonist, NIBR189, inhibited lipopolysaccharide-induced cell migration indicating the involvement of EBI2 and its ligand in brain cell migration under inflammatory conditions.
EBI2受体的内源性配体——氧化甾醇7α,25OHC，对免疫反应至关重要，受CH25H、CYP7B1和HSD3B7酶的精细调控。T细胞滤泡内的淋巴基质细胞和滤泡树突状细胞维持着7α,25OHC梯度，基质细胞使其浓度升高，而树突状细胞使其浓度降低。这种梯度对于B细胞在淋巴组织中的正确定位至关重要。在多发性硬化症的动物模型——实验性自身免疫性脑脊髓炎中，中枢神经系统中7α,25OHC的水平迅速升高，驱动表达EBI2的免疫细胞通过血脑屏障迁移。为了探究脑内血管细胞是否表达这些酶，我们检查了正常小鼠脑微血管，并研究了炎症过程中它们表达的变化。Ebi2在内皮细胞、周细胞/平滑肌细胞和星形胶质细胞终足中大量表达。Ch25h、Cyp7b1和Hsd3b7在每种细胞类型中均有不同程度的检测到，表明它们在正常条件下积极参与氧化甾醇7α,25OHC的合成和梯度维持。小鼠和人类血脑屏障形成细胞在EBI2和酶水平上出现了显著的物种特异性差异。在急性炎症条件下，脑内发生了Ebi2和合成酶的调节，变化的幅度和方向取决于酶。最后，在体外星形胶质细胞迁移模型中，CYP7B1抑制剂克霉唑以及EBI2拮抗剂NIBR189抑制了脂多糖诱导的细胞迁移，表明EBI2及其配体在炎症条件下参与了脑细胞迁移。
