Molecular Defense Section, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20892; and.
Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852; and.
J Immunol. 2019 Jan 15;202(2):428-440. doi: 10.4049/jimmunol.1601395. Epub 2018 Dec 17.
Engagement of the BCR with Ags triggers signaling pathways for commitment of B lymphocyte responses that can be regulated, in part, by reactive oxygen species. To investigate the functional relevance of reactive oxygen species produced in primary B cells, we focused on the role of the hydrogen peroxide generator Duox1 in stimulated splenic B cells under the influence of the T2 cytokine IL-4. We found that HO production in wild type (WT) and Nox2-deficient CD19 B cells was boosted concomitantly with enhanced expression of Duox1 following costimulation with BCR agonists together with IL-4, whereas stimulated Duox1 cells showed attenuated HO release. We examined whether Duox1-derived HO contributes to proliferative activity and Ig isotype production in CD19 cells upon BCR stimulation. Duox1 CD19 B cells showed normal responses of Ig production but a higher rate of proliferation than WT or Nox2-deficient cells. Furthermore, we demonstrated that the HO scavenger catalase mimics the effect of Duox1 deficiency by enhancing proliferation of WT CD19 B cells in vitro. Results from immunized mice reflected the in vitro observations: T cell-independent Ag induced increased B cell expansion in germinal centers from Duox1 mice relative to WT and Nox2 mice, whereas immunization with T cell-dependent or -independent Ag elicited normal Ig isotype secretion in the Duox1 mutant mice. These observations, obtained both by in vitro and in vivo approaches, strongly suggest that Duox1-derived hydrogen peroxide negatively regulates proliferative activity but not Ig isotype production in primary splenic CD19 B cells.
BCR 与 Ags 的结合触发了 B 淋巴细胞反应的信号通路，这些信号通路可以部分受到活性氧的调节。为了研究初级 B 细胞中产生的活性氧的功能相关性，我们专注于 T2 细胞因子 IL-4 影响下刺激的脾 B 细胞中过氧化氢生成酶 Duox1 的作用。我们发现，在与 BCR 激动剂和 IL-4 共刺激后，野生型（WT）和 Nox2 缺陷型 CD19 B 细胞中的 HO 产生与 Duox1 的增强表达同时增强，而刺激的 Duox1 细胞显示出 HO 释放的减弱。我们检查了 Duox1 衍生的 HO 是否有助于 CD19 细胞在 BCR 刺激下的增殖活性和 Ig 同种型产生。Duox1 CD19 B 细胞显示出正常的 Ig 产生反应，但比 WT 或 Nox2 缺陷型细胞具有更高的增殖率。此外，我们证明 HO 清除剂过氧化氢酶通过增强 WT CD19 B 细胞在体外的增殖来模拟 Duox1 缺陷的作用。免疫小鼠的结果反映了体外观察：与 WT 和 Nox2 小鼠相比，T 细胞非依赖性 Ag 诱导 Duox1 小鼠生发中心中的 B 细胞扩增增加，而 T 细胞依赖性或非依赖性 Ag 免疫在 Duox1 突变小鼠中引起正常的 Ig 同种型分泌。这些通过体外和体内方法获得的观察结果强烈表明，Duox1 衍生的过氧化氢负调节初级脾 CD19 B 细胞中的增殖活性，但不调节 Ig 同种型产生。
