UIM en Inmunologia, Hospital de Pediatría, CMN SIGLO XXI, Instituto Mexicano del Seguro Social, Mexico City 06720, Mexico.
Unidad de Investigación en Virología y Cáncer, Hospital Infantil de Mexico Federico Gómez, Mexico City 06720, Mexico.
Cells. 2021 Feb 4;10(2):316. doi: 10.3390/cells10020316.
Self-reactive immature B cells are eliminated through apoptosis by tolerance mechanisms, failing to eliminate these cells results in autoimmune diseases. Prolactin is known to rescue immature B cells from B cell receptor engagement-induced apoptosis in lupus-prone mice. The objective of this study was to characterize in vitro prolactin signaling in immature B cells, using sorting, PCR array, RT-PCR, flow cytometry, and chromatin immunoprecipitation. We found that all B cell maturation stages in bone marrow express the prolactin receptor long isoform, in both wild-type and MRL/lpr mice, but its expression increased only in the immature B cells of the latter, particularly at the onset of lupus. In these cells, activation of the prolactin receptor promoted STAT3 phosphorylation and upregulation of the antiapoptotic Bcl2a1a, Bcl2l2, and Birc5 genes. STAT3 binding to the promoter region of these genes was confirmed through chromatin immunoprecipitation. Furthermore, inhibitors of prolactin signaling and STAT3 activation abolished the prolactin rescue of self-engaged MRL/lpr immature B cells. These results support a mechanism in which prolactin participates in the emergence of lupus through the rescue of self-reactive immature B cell clones from central tolerance clonal deletion through the activation of STAT3 and transcriptional regulation of a complex network of genes related to apoptosis resistance.
自身反应性未成熟 B 细胞通过耐受机制通过细胞凋亡被消除，如果不能消除这些细胞，就会导致自身免疫性疾病。已知催乳素可挽救狼疮易感小鼠中 B 细胞受体交联诱导的未成熟 B 细胞凋亡。本研究的目的是使用分选、PCR 阵列、RT-PCR、流式细胞术和染色质免疫沉淀来描述体外催乳素信号在未成熟 B 细胞中的作用。我们发现骨髓中的所有 B 细胞成熟阶段在野生型和 MRL/lpr 小鼠中均表达催乳素受体长型，但其表达仅在后者的未成熟 B 细胞中增加，尤其是在狼疮发病时。在这些细胞中，催乳素受体的激活促进了 STAT3 磷酸化和抗凋亡基因 Bcl2a1a、Bcl2l2 和 Birc5 的上调。通过染色质免疫沉淀证实了 STAT3 结合到这些基因启动子区域。此外，催乳素信号和 STAT3 激活抑制剂消除了催乳素对自身结合的 MRL/lpr 未成熟 B 细胞的挽救作用。这些结果支持一种机制，即催乳素通过激活 STAT3 和转录调节与抗凋亡相关的复杂基因网络，参与狼疮的发生，从而从中枢耐受克隆删除中挽救自身反应性未成熟 B 细胞克隆。
