Department of Hematology, Peking University First Hospital, Beijing, China.
Department of Hebei Provincial Key Laboratory of Tumor Microenvironment and Drug Resistance, The Fourth Affiliated Hospital of Hebei Medical University, Shijiazhuang, Hebei, China.
Transplantation. 2023 Jan 1;107(1):140-155. doi: 10.1097/TP.0000000000004245. Epub 2022 Dec 8.
Fibroblastic reticular cells (FRCs) are a type of stromal cells located in the T zone in secondary lymphoid organs. Previous studies showed that FRCs possess the potential to promote myeloid differentiation. We aim to investigate whether FRCs in lymph nodes (LNs) could induce tolerogenic macrophage generation and further influence T-cell immunity at an early stage of allogeneic hematopoietic stem cell transplantation (allo-HSCT).
LNs were assayed to confirm the existence of proliferating macrophages after allo-HSCT. Ex vivo-expanded FRCs and bone marrow cells were cocultured to verify the generation of macrophages. Real-time quantitative PCR and ELISA assays were performed to observe the cytokines expressed by FRC. Transcriptome sequencing was performed to compare the difference between FRC-induced macrophages (FMs) and conventional macrophages. Mixed lymphocyte reaction and the utilization of FMs in acute graft-versus-host disease (aGVHD) mice were used to test the inhibitory function of FMs in T-cell immunity in vitro and in vivo.
We found a large number of proliferating macrophages near FRCs in LNs with tolerogenic phenotype under allo-HSCT conditions. Neutralizing anti-macrophage colony-stimulating factor receptor antibody abolished FMs generation in vitro. Phenotypic analysis and transcriptome sequencing suggested FMs possessed immunoinhibitory function. Mixed lymphocyte reaction proved that FMs could inhibit T-cell activation and differentiation toward Th1/Tc1 cells. Injection of FMs in aGVHD mice effectively attenuated aGVHD severity and mortality.
This study has revealed a novel mechanism of immune regulation through the generation of FRC-induced tolerogenic macrophages in LNs at an early stage of allo-HSCT.
纤维母细胞网状细胞（FRCs）是位于次级淋巴器官 T 区的一种基质细胞。先前的研究表明，FRCs 具有促进髓样细胞分化的潜力。我们旨在研究淋巴结（LNs）中的 FRC 是否可以诱导耐受性巨噬细胞的产生，并在异基因造血干细胞移植（allo-HSCT）的早期阶段进一步影响 T 细胞免疫。
检测 allo-HSCT 后 LNs 中是否存在增殖的巨噬细胞。进行体外扩增的 FRC 和骨髓细胞共培养，以验证巨噬细胞的生成。实时定量 PCR 和 ELISA 检测观察 FRC 表达的细胞因子。进行转录组测序以比较 FRC 诱导的巨噬细胞（FMs）与常规巨噬细胞之间的差异。混合淋巴细胞反应和急性移植物抗宿主病（aGVHD）小鼠中 FMs 的利用用于测试 FMs 在体外和体内对 T 细胞免疫的抑制功能。
我们发现 allo-HSCT 条件下 LNs 中 FRC 附近存在大量具有耐受性表型的增殖巨噬细胞。中和抗巨噬细胞集落刺激因子受体抗体可消除体外 FMs 的产生。表型分析和转录组测序表明 FMs 具有免疫抑制功能。混合淋巴细胞反应证明 FMs 可抑制 T 细胞向 Th1/Tc1 细胞的激活和分化。在 aGVHD 小鼠中注射 FMs 可有效减轻 aGVHD 的严重程度和死亡率。
本研究揭示了一种新的免疫调节机制，即在 allo-HSCT 的早期阶段通过 LNs 中 FRC 诱导产生耐受性巨噬细胞来实现。
