Sae-Khow Kritsanawan, Charoensappakit Awirut, Udompornpitak Kanyarat, Saisorn Wilasinee, Issara-Amphorn Jiraphorn, Palaga Tanapat, Leelahavanichkul Asada
Center of Excellence in Translational Research in Inflammation and Immunology (CETRII), Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Department of Clinical Microscopy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand.
Cell Death Discov. 2025 Feb 17;11(1):63. doi: 10.1038/s41420-025-02342-x.
Spleen tyrosine kinase (Syk), an important hub of immune signaling, is activated by several signalings in active lupus which could be interfered by Syk inhibitor but is still not completely evaluated in innate immune cells associated with lupus activity. Hence, a Syk inhibitor (fostamatinib; R788) was tested in vivo using Fc gamma receptor-deficient (FcγRIIb) lupus mice and in vitro (macrophages and neutrophils). After 4 weeks of oral Syk inhibitor, 40 week-old FcγRIIb mice (a full-blown lupus model) demonstrated less prominent lupus parameters (serum anti-dsDNA, proteinuria, and glomerulonephritis), systemic inflammation, as evaluated by serum TNFa, IL-6, and citrullinated histone H3 (CitH3), gut permeability defect, as indicated by serum FITC dextran assay, serum lipopolysaccharide (LPS), and serum (1 → 3)-β-D-glucan (BG), extracellular traps (ETs) and immune complex deposition in spleens and kidneys (immunofluorescent staining of CitH3 and immunoglobulin G) than FcγRIIb mice with placebo. Due to the spontaneous elevation of LPS and BG in serum, LPS plus BG (LPS + BG) was used to activate macrophages and neutrophils. After LPS + BG stimulation, FcγRIIb macrophages and neutrophils demonstrated predominant abundance of phosphorylated Syk (Western blotting), and the pro-inflammatory responses (CD86 flow cytometry analysis, supernatant cytokines, ETs immunofluorescent, and flow cytometry-based apoptosis). With RNA sequencing analysis and western blotting, the Syk-p38MAPK-dependent pathway was suggested as downregulating several inflammatory pathways in LPS + BG-activated FcγRIIb macrophages and neutrophils. Although both inhibitors against Syk and p38MAPK attenuated macrophage and neutrophil inflammatory responses against LPS + WGP, the apoptosis inhibition by p38MAPK inhibitor was not observed. These results suggested that Syk inhibitor (fostamatinib) improved the severity of lupus caused by FcγRIIb defect partly through Syk-p38MAPK anti-inflammation that inhibited both ET formation and cytokine production from innate immune cells.
脾酪氨酸激酶（Syk）是免疫信号的重要枢纽，在活动性狼疮中可被多种信号激活，Syk抑制剂可对其产生干扰，但在与狼疮活动相关的固有免疫细胞中仍未得到充分评估。因此，使用Fcγ受体缺陷（FcγRIIb）狼疮小鼠在体内以及在体外（巨噬细胞和中性粒细胞）对Syk抑制剂（ fostamatinib；R788）进行了测试。口服Syk抑制剂4周后，40周龄的FcγRIIb小鼠（一种典型的狼疮模型）的狼疮参数（血清抗双链DNA、蛋白尿和肾小球肾炎）、全身炎症（通过血清TNFα、IL-6和瓜氨酸化组蛋白H3（CitH3）评估）、肠道通透性缺陷（通过血清异硫氰酸荧光素葡聚糖测定、血清脂多糖（LPS）和血清（1→3）-β-D-葡聚糖（BG）表明）、细胞外陷阱（ETs）以及脾脏和肾脏中的免疫复合物沉积（CitH3和免疫球蛋白G的免疫荧光染色）均不如给予安慰剂的FcγRIIb小鼠明显。由于血清中LPS和BG的自发升高，因此使用LPS加BG（LPS + BG）来激活巨噬细胞和中性粒细胞。在LPS + BG刺激后，FcγRIIb巨噬细胞和中性粒细胞显示出磷酸化Syk的大量存在（蛋白质印迹法），以及促炎反应（CD86流式细胞术分析、上清液细胞因子、ETs免疫荧光和基于流式细胞术的细胞凋亡）。通过RNA测序分析和蛋白质印迹法，提示Syk-p38丝裂原活化蛋白激酶（MAPK）依赖性途径可下调LPS + BG激活的FcγRIIb巨噬细胞和中性粒细胞中的多种炎症途径。尽管针对Syk和p38MAPK的抑制剂均减弱了巨噬细胞和中性粒细胞对LPS + WGP的炎症反应，但未观察到p38MAPK抑制剂对细胞凋亡的抑制作用。这些结果表明，Syk抑制剂（fostamatinib）部分通过Syk-p38MAPK抗炎作用改善了由FcγRIIb缺陷引起的狼疮严重程度，该抗炎作用抑制了固有免疫细胞中ET的形成和细胞因子的产生。
