Department of Rheumatology and Immunology, Peking University People's Hospital & Beijing Key Laboratory for Rheumatism Mechanism and Immune Diagnosis (BZ0135), Peking University People's Hospital, Beijing, China.
Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China.
Lupus Sci Med. 2023 Jul;10(2). doi: 10.1136/lupus-2023-000974.
Recently, a new subtype of granzyme B (GrB)-producing Breg cells has been identified, which was proven to be involved in autoimmune disease. Our recent report demonstrated that GrB-producing Breg cells were correlated with clinical and immunological features of SLE. However, the effect of GrB-producing Breg cells in lupus mice is unclear.
GrB expression in naïve and lupus mouse B cells was analysed using flow cytometry, PCR, ELISA and ELISpot assays. To study the role of GrB-producing B cells in a lupus model, GrB knockout (KO) and wild-type (WT) mice were intraperitoneally injected with monoclonal cells from the mutant mouse strain B6.C-H-2bm12 (bm12) for 2 weeks. In addition, the function of GrB-producing Breg cells in naïve and lupus mice was further explored using in vitro B cells-CD4CD25 T cell co-culture assays with GrB blockade/KO of B cells.
B cells from the spleens of WT C57BL/6 (B6) mice could express and secret GrB (p<0.001). GrB-producing Breg cells from WT mice showed their regulatory functions on CD4CD25 T cell. While the frequency of GrB-producing Breg cells was significantly decreased (p=0.001) in lupus mice (p<0.001). Moreover, GrB-producing Breg cells in lupus mice failed to suppress T cell-mediated proinflammatory responses, partially due to the impaired capacity of downregulating the T cell receptor-zeta chain and inducing CD4CD25 T cell apoptosis.
This study further revealed the function and mechanism of GrB-producing Breg cells in regulating T cell homeostasis in lupus mice and highlighted GrB-producing Breg cells as a therapeutic target in SLE.
最近，人们发现了一种新型的颗粒酶 B（GrB）产生 Breg 细胞亚群，该细胞亚群被证明与自身免疫性疾病有关。我们最近的报告表明，GrB 产生的 Breg 细胞与 SLE 的临床和免疫学特征相关。然而，GrB 产生的 Breg 细胞在狼疮小鼠中的作用尚不清楚。
使用流式细胞术、PCR、ELISA 和 ELISpot 检测分析 naive 和狼疮小鼠 B 细胞中的 GrB 表达。为了研究 GrB 产生的 B 细胞在狼疮模型中的作用，将 GrB 敲除（KO）和野生型（WT）小鼠腹腔内注射来自突变小鼠株 B6.C-H-2bm12（bm12）的单克隆细胞 2 周。此外，还通过体外 B 细胞-CD4CD25 T 细胞共培养实验以及 B 细胞的 GrB 阻断/KO 进一步探讨了 naive 和狼疮小鼠中 GrB 产生的 Breg 细胞的功能。
WT C57BL/6（B6）小鼠脾脏中的 B 细胞可以表达和分泌 GrB（p<0.001）。WT 小鼠的 GrB 产生的 Breg 细胞对 CD4CD25 T 细胞具有调节作用。而狼疮小鼠中 GrB 产生的 Breg 细胞的频率显著降低（p=0.001）（p<0.001）。此外，狼疮小鼠中的 GrB 产生的 Breg 细胞未能抑制 T 细胞介导的促炎反应，部分原因是下调 T 细胞受体-zeta 链和诱导 CD4CD25 T 细胞凋亡的能力受损。
本研究进一步揭示了 GrB 产生的 Breg 细胞在调节狼疮小鼠 T 细胞稳态中的功能和机制，并强调了 GrB 产生的 Breg 细胞作为 SLE 的治疗靶点。
