Luo Yubin, Boyle David L, Hammaker Deepa, Edgar Meghan, Franzoso Guido, Firestein Gary S
University of California, San Diego at La Jolla.
Arthritis Rheum. 2011 Oct;63(10):2949-55. doi: 10.1002/art.30497.
Growth arrest and DNA damage-inducible protein 45β (GADD45β) is involved in stress responses, cell cycle regulation, and oncogenesis. Previous studies demonstrated that GADD45β deficiency exacerbates K/BxN serum-induced arthritis and experimental allergic encephalomyelitis (EAE) in mice, indicating that GADD45β plays a suppressive role in innate and adaptive immune responses. To further understand how GADD45β regulates autoimmunity, we evaluated collagen-induced arthritis in GADD45β-/- mice.
Wild-type (WT) and GADD45β-/- DBA/1 mice were immunized with bovine type II collagen (CII). Serum anticollagen antibody levels were quantified by enzyme-linked immunosorbent assay. Expression of cytokines and matrix metalloproteinases in the joint and spleen was determined by quantitative polymerase chain reaction. The in vitro T cell cytokine response to CII was measured by multiplex analysis. CD4+CD25+ Treg cells and Th17 cells were quantified using flow cytometry.
GADD45β-/- mice showed significantly lower arthritis severity and joint destruction compared with WT mice. MMP-3 and MMP-13 expression was also markedly reduced in GADD45β-/- mice. However, serum anti-CII antibody levels were similar in both groups. FoxP3 and interleukin-10 (IL-10) expression was increased 2-3-fold in splenocytes from arthritic GADD45β-/- mice compared with those from WT mice. Flow cytometric analysis showed greater numbers of CD4+CD25+ Treg cells in the spleen of GADD45β-/- mice than in the spleen of WT mice. In vitro studies showed that interferon-γ and IL-17 production by T cells was significantly decreased in GADD45β-/- mice.
Unlike passive K/BxN arthritis and EAE, GADD45β deficiency in CIA was associated with lower arthritis severity, elevated IL-10 expression, decreased IL-17 production, and increased numbers of Treg cells. The data suggest that GADD45β plays a complex role in regulating adaptive immunity and, depending on the model, either enhances or suppresses inflammation.
生长停滞和DNA损伤诱导蛋白45β（GADD45β）参与应激反应、细胞周期调控和肿瘤发生。先前的研究表明，GADD45β缺陷会加重小鼠K/BxN血清诱导的关节炎和实验性自身免疫性脑脊髓炎（EAE），这表明GADD45β在先天性和适应性免疫反应中起抑制作用。为了进一步了解GADD45β如何调节自身免疫，我们评估了GADD45β基因敲除小鼠的胶原诱导性关节炎。
用牛II型胶原（CII）免疫野生型（WT）和GADD45β基因敲除的DBA/1小鼠。通过酶联免疫吸附测定法定量血清抗胶原抗体水平。通过定量聚合酶链反应测定关节和脾脏中细胞因子和基质金属蛋白酶的表达。通过多重分析测量体外T细胞对CII的细胞因子反应。使用流式细胞术对CD4+CD25+调节性T细胞（Treg细胞）和辅助性T细胞17（Th17细胞）进行定量。
与WT小鼠相比，GADD45β基因敲除小鼠的关节炎严重程度和关节破坏明显更低。GADD45β基因敲除小鼠中基质金属蛋白酶-3（MMP-3）和基质金属蛋白酶-13（MMP-13）的表达也明显降低。然而，两组的血清抗CII抗体水平相似。与WT小鼠相比，来自患有关节炎的GADD45β基因敲除小鼠的脾细胞中叉头框蛋白P3（FoxP3）和白细胞介素-10（IL-10）的表达增加了2至3倍。流式细胞术分析显示，GADD45β基因敲除小鼠脾脏中的CD4+CD25+Treg细胞数量多于WT小鼠脾脏中的数量。体外研究表明，GADD45β基因敲除小鼠中T细胞产生的干扰素-γ和IL-17明显减少。
与被动性K/BxN关节炎和EAE不同，CIA中GADD45β缺陷与较低的关节炎严重程度、升高的IL-10表达、减少的IL-17产生以及增加的Treg细胞数量相关。数据表明，GADD45β在调节适应性免疫中起复杂作用，并且根据模型的不同，它可以增强或抑制炎症。
