Ittah Marc, Miceli-Richard Corinne, Gottenberg Jacques-Eric, Sellam Jérémie, Lepajolec Christine, Mariette Xavier
Rhumatologie, Institut Pour la Santé et la Recherche Médicale, Hôpital Bicêtre, Assistance Publique-Hôpitaux de Paris, Université Paris-Sud 11, Le Kremlin Bicêtre, France.
Eur J Immunol. 2009 May;39(5):1271-9. doi: 10.1002/eji.200839086.
B-cell-activating factor (BAFF) plays a key role in promoting activation of autoimmune B cells. This cytokine may be expressed in and secreted by salivary gland epithelial cells (SGEC) after stimulation with type I IFN or viral or synthetic dsRNA. Because this BAFF expression depends only in part on endosomal TLR and type I IFN, we investigated whether other dsRNA sensors could be implicated in BAFF expression. Using human SGEC, we confirmed the partial dependence of BAFF expression on TLR-3 by replicating the partial inhibition of BAFF expression observed upon endosomal inhibition using TLR-3 or Toll/IL-1R domain-containing protein inducing IFN-beta silencing mRNA, but not with TLR-7 silencing mRNA. Melanoma differentiation-associated gene 5 silencing mRNA had no effect on BAFF expression, but retinoic acid-inducible gene I silencing mRNA had a slight effect observed following infection with dsRNA reovirus-1. Inhibition of RNA-activated protein kinase (PKR) by 2-aminopurine completely abolished both BAFF mRNA and protein production after reovirus-1 infection and poly(I:C) stimulation through NF-kappaB and p38 MAPK pathways, with the latter implicated only after poly(I:C) stimulation. Thus, PKR is the dsRNA sensor implicated in BAFF induction in SGEC after dsRNA stimulation. In autoimmune diseases, PKR may be an interesting target for preventing BAFF following the induction of innate immunity.
B细胞激活因子(BAFF)在促进自身免疫性B细胞激活中起关键作用。这种细胞因子可能在受到I型干扰素、病毒或合成双链RNA刺激后,由唾液腺上皮细胞(SGEC)表达并分泌。由于这种BAFF表达仅部分依赖于内体Toll样受体(TLR)和I型干扰素,我们研究了其他双链RNA传感器是否与BAFF表达有关。使用人类SGEC,我们通过复制使用TLR-3或含Toll/白细胞介素-1受体结构域蛋白诱导干扰素-β沉默mRNA对内体抑制后观察到的BAFF表达的部分抑制,证实了BAFF表达对TLR-3的部分依赖性,但使用TLR-7沉默mRNA则没有这种效果。黑色素瘤分化相关基因5沉默mRNA对BAFF表达没有影响,但在用双链RNA呼肠孤病毒-1感染后观察到维甲酸诱导基因I沉默mRNA有轻微影响。2-氨基嘌呤对RNA激活蛋白激酶(PKR)的抑制完全消除了呼肠孤病毒-1感染和聚肌胞苷酸(poly(I:C))刺激后通过核因子κB(NF-κB)和p38丝裂原活化蛋白激酶(MAPK)途径产生的BAFF mRNA和蛋白,其中后者仅在poly(I:C)刺激后起作用。因此,PKR是双链RNA刺激后SGEC中参与BAFF诱导的双链RNA传感器。在自身免疫性疾病中,PKR可能是在先天免疫诱导后预防BAFF的一个有意义的靶点。