Università Vita-Salute San Raffaele, IRCCS San Raffaele Scientific Institute, Milan, Italy; Ragon Institute of MGH, MIT, and Harvard, Massachusetts General Hospital, Harvard Medical School, Boston, Mass; Unit of Immunology, Rheumatology, Allergy, and Rare Diseases, IRCCS San Raffaele Scientific Institute, Milan, Italy.
Università Vita-Salute San Raffaele, IRCCS San Raffaele Scientific Institute, Milan, Italy.
J Allergy Clin Immunol. 2020 Mar;145(3):968-981.e14. doi: 10.1016/j.jaci.2019.07.004. Epub 2019 Jul 15.
IgG-related disease (IgG-RD) is a fibroinflammatory condition marked by rapid clinical improvement after selective depletion of B lymphocytes with rituximab. This feature suggests that B cells might participate in fibrogenesis and wound healing.
In the present work we aimed to demonstrate that B lymphocytes contribute directly to tissue fibrosis in patients with IgG-RD.
Total circulating CD19 B lymphocytes, naive B cells, memory B cells, or plasmablasts from patients with IgG-RD were cultivated with human fibroblasts. Profibrotic soluble factors and collagen production in cocultures were assessed by using ELISAs and Luminex assays. RNA sequencing and quantitative RT-PCR were used to assess fibroblast activation in the presence of B cells, as well as induction of profibrotic pathways in B-cell subsets. Relevant profibrotic and inflammatory molecules were confirmed in vitro by using functional experiments and on IgG-RD tissue sections by using multicolor immunofluorescence studies.
B cells from patients with IgG-RD (1) produced the profibrotic molecule platelet-derived growth factor B and stimulated collagen production by fibroblasts; (2) expressed enzymes implicated in extracellular matrix remodeling, such as lysyl oxidase homolog 2; (3) produced the chemotactic factors CCL4, CCL5, and CCL11; and (4) induced production of these same chemokines by activated fibroblasts. Plasmablasts expressed sets of genes implicated in fibroblast activation and proliferation and therefore represent cells with intrinsic profibrotic properties.
We have demonstrated that B cells contribute directly to tissue fibrosis in patients with IgG-RD. These unanticipated profibrotic properties of B lymphocytes, particularly plasmablasts, might be relevant for fibrogenesis in patients with other fibroinflammatory disorders and for wound-healing processes in physiologic conditions.
免疫球蛋白 G（IgG）相关疾病（IgG-RD）是一种纤维炎症性疾病，其特征为用利妥昔单抗选择性耗竭 B 淋巴细胞后临床迅速改善。这一特征提示 B 细胞可能参与纤维化和伤口愈合。
本研究旨在证明 IgG-RD 患者的 B 淋巴细胞直接参与组织纤维化。
从 IgG-RD 患者中提取循环总 CD19+B 淋巴细胞、幼稚 B 细胞、记忆 B 细胞或浆母细胞，与成纤维细胞共培养。采用 ELISA 和 Luminex 检测共培养物中促纤维化可溶性因子和胶原的产生。采用 RNA 测序和定量 RT-PCR 检测 B 细胞存在时成纤维细胞的激活以及 B 细胞亚群中促纤维化途径的诱导。通过功能实验在体外验证相关促纤维化和炎症分子，并通过多色免疫荧光研究在 IgG-RD 组织切片中验证。
来自 IgG-RD 患者的 B 细胞（1）产生了促纤维化分子血小板衍生生长因子 B，并刺激成纤维细胞产生胶原；（2）表达了细胞外基质重塑相关的酶，如赖氨酰氧化酶同源物 2；（3）产生了趋化因子 CCL4、CCL5 和 CCL11；（4）诱导激活的成纤维细胞产生这些相同的趋化因子。浆母细胞表达了与成纤维细胞激活和增殖相关的基因集，因此代表具有内在促纤维化特性的细胞。
我们已经证明 IgG-RD 患者的 B 细胞直接参与组织纤维化。B 淋巴细胞，特别是浆母细胞的这些意想不到的促纤维化特性，可能与其他纤维炎症性疾病中的纤维化以及生理条件下的伤口愈合过程有关。
