IRF4-Dependent and IRF4-Independent Pathways Contribute to DC Dysfunction in Lupus

Interferon Regulatory Factors (IRFs) play fundamental roles in dendritic cell (DC) differentiation and function. In particular, IRFs are critical transducers of TLR signaling and dysregulation in this family of factors is associated with the development of autoimmune disorders such as Systemic Lupus Erythematosus (SLE). While several IRFs are expressed in DCs their relative contribution to the aberrant phenotypic and functional characteristics that DCs acquire in autoimmune disease has not been fully delineated. Mice deficient in both DEF6 and SWAP-70 (= Double-knock-out or DKO mice), two members of a unique family of molecules that restrain IRF4 function, spontaneously develop a lupus-like disease. Although autoimmunity in DKO mice is accompanied by dysregulated IRF4 activity in both T and B cells, SWAP-70 is also known to regulate multiple aspects of DC biology leading us to directly evaluate DC development and function in these mice. By monitoring Blimp1 expression and IL-10 competency in DKO mice we demonstrate that DCs in these mice exhibit dysregulated IL-10 production, which is accompanied by aberrant Blimp1 expression in the spleen but not in the peripheral lymph nodes. We furthermore show that DCs from these mice are hyper-responsive to multiple TLR ligands and that IRF4 plays a differential role in in these responses by being required for the TLR4-mediated but not the TLR9-mediated upregulation of IL-10 expression. Thus, DC dysfunction in lupus-prone mice relies on both IRF4-dependent and IRF4-independent pathways.     

血管损伤的新靶点：干扰素调节因子

内膜增生是血管损伤后动脉重塑过程中普遍存在的现象。血管平滑肌细胞（vascular smooth muscle cells,VSMCs）的增殖、迁移、表型转换是血管损伤性疾病高血压、动脉粥样硬化、血管成形术后再狭窄等的共同病理生理学过程。干扰素调节因子（interferon regulatory factors,IRFs）是一类能对干扰素基因表达起到免疫调节作用的转录因子。近来研究发现,其在血管损伤病理过程具有调节作用,其中IRF1与细胞生长、分化和损伤密切相关,IRF3与IRF7可以抑制新生内膜的形成,而IRF8和IRF9则促进VSMCs增殖、迁移及血管内膜增生。本文重点介绍了IRFs的结构特征、信号途径及在血管重塑过程中作为新型调控因子的功能。