Kidney Disease Center, First Affiliated Hospital, Zhejiang University, School of Medicine, Key Laboratory of Nephropathy, Zhejiang Province, Hangzhou, Zhejiang, China; National Clinical Research Base of Traditional Chinese Medicine, Zhejiang Hospital of Traditional Chinese Medicine, Zhejiang Chinese Medical University, Hangzhou, China.
Kidney Disease Center, First Affiliated Hospital, Zhejiang University, School of Medicine, Key Laboratory of Nephropathy, Zhejiang Province, Hangzhou, Zhejiang, China; National Clinical Research Base of Traditional Chinese Medicine, Zhejiang Hospital of Traditional Chinese Medicine, Zhejiang Chinese Medical University, Hangzhou, China.
Exp Cell Res. 2018 Jan 1;362(1):121-131. doi: 10.1016/j.yexcr.2017.11.009. Epub 2017 Nov 11.
Two different types of FcRs for IgG are constitutively expressed on the surface of human neutrophils, namely, FcγRIIA (CD32a) and FcγRIIIB (CD16b). Unlike FcγRIIA, FcγRIIIb is GPI anchored to the cell membrane and its signal transduction is still ambiguous. To further understand the signal transduction of CD16b, we compared neutrophil cytokine expression and apoptosis by the cross-linking of CD32a and CD16b respectively. We found that both CD32a and CD16b crosslinking can activate neutrophils, but did not exactly share cytokine expression profiles. On the other hand, CD16b cross-linking retarded neutrophil apoptosis while CD32a promoted it. By interrupting the lipid raft with methyl-β-cyclodextrin (MβCD) and inhibiting the ITAM-SYK pathway with an SYK inhibitor (piceatannol), we found reduced apoptosis was at least partially mediated by lipid raft structure, but not the ITAM-SYK pathway. Additionally, CD16b but not CD32a cross-linking triggered SHP-2 phosphorylation and led to its translocation into lipid rafts. SHP-2 phosphorylation and translocation were inhibited by MβCD. Moreover, pre-inhibition of SHP-2 by a specific inhibitor (SHP099) converted IL-10 and SOCS3 expression level and promoted neutrophil apoptosis after CD16b crosslinking. In conclusion, these results, for the first time, collectively indicate that SHP-2 is activated by CD16b crosslinking in neutrophils and functions as a component of the raft-mediated signaling pathway.
两种不同类型的 IgG Fc 受体（FcγR）在人类中性粒细胞表面持续表达，即 FcγRIIA（CD32a）和 FcγRIIIB（CD16b）。与 FcγRIIA 不同，FcγRIIIb 通过 GPI 锚定在细胞膜上，其信号转导仍不明确。为了进一步了解 CD16b 的信号转导，我们分别通过交联 CD32a 和 CD16b 比较了中性粒细胞细胞因子表达和凋亡。我们发现 CD32a 和 CD16b 交联均可激活中性粒细胞，但并不完全共享细胞因子表达谱。另一方面，CD16b 交联延迟中性粒细胞凋亡，而 CD32a 促进其凋亡。用甲基-β-环糊精（MβCD）中断脂筏结构并使用 SYK 抑制剂（piceatannol）抑制 ITAM-SYK 途径后，我们发现减少的凋亡至少部分是由脂筏结构介导的，而不是 ITAM-SYK 途径。此外，CD16b 交联而非 CD32a 交联触发 SHP-2 磷酸化并导致其易位至脂筏。MβCD 抑制 SHP-2 磷酸化和易位。此外，通过特异性抑制剂（SHP099）预先抑制 SHP-2 可改变 CD16b 交联后 IL-10 和 SOCS3 表达水平并促进中性粒细胞凋亡。总之，这些结果首次共同表明，SHP-2 被中性粒细胞中的 CD16b 交联激活，并作为脂筏介导的信号通路的组成部分发挥作用。
