Department of Immunology, Erasmus MC, , Rotterdam, Zuid-holland, The Netherlands.
Ann Rheum Dis. 2014 Jun;73(6):1052-9. doi: 10.1136/annrheumdis-2012-202552. Epub 2013 Jul 6.
To establish an easy and practical assay for identifying systemic interferon (IFN) type I bioactivity in patients with primary Sjögren's syndrome (pSS). The IFN type I signature is present in over half of the pSS patients and identifies a subgroup with a higher disease activity. This signature is currently assessed via laborious expression profiles of multiple IFN type I-inducible genes.
In a cohort of 35 pSS patients, myxovirus-resistance protein A (MxA) was assessed as a potential biomarker for type I IFN activity, using an enzyme immunoassay (EIA) on whole-blood and flow cytometric analyses (fluorescence-activated cell sorting, FACS) of isolated CD14 monocytes. In addition, potential biomarkers such as CD64, CD169 and B cell-activating factor (BAFF) were simultaneously analysed in CD14 monocytes using FACS. The IFNscore, a measure for total type I IFN bioactivity, was calculated using expression values of the IFN type I signature genes--IFI44, IFI44L, IFIT3, LY6E and MX1--in CD14 monocytes, determined by real-time quantitative PCR.
IFNscores correlated the strongest with monocyte MxA protein (r=0.741, p<0.001) and whole-blood MxA levels (r=0.764, p<0.001), weaker with CD169 (r=0.495, p<0.001) and CD64 (r=0.436, p=0.007), and not at all with BAFF protein. In particular, whole blood MxA levels correlated with EULAR Sjögren's Syndrome Disease Activity Index scores and numerous clinical pSS parameters. Interestingly, patients on hydroxychloroquine showed reduced MxA levels (EIA, p=0.04; FACS p=0.001).
The MxA assays were excellent tools to assess IFN type I activity in pSS, MxA-EIA being the most practical. MxA levels associate with features of active disease and are reduced in hydroxychloroquine-treated patients, suggesting the clinical applicability of MxA in stratifying patients according to IFN positivity.
建立一种简单实用的方法来鉴定原发性干燥综合征（pSS）患者的系统性干扰素（IFN）I 型生物活性。IFN I 型特征存在于超过一半的 pSS 患者中，并确定了一个具有更高疾病活动度的亚组。目前，通过对多个 IFN I 型诱导基因的表达谱进行繁琐的评估来检测这种特征。
在 35 名 pSS 患者的队列中，使用酶联免疫吸附试验（EIA）检测全血和分离的 CD14 单核细胞的流式细胞分析（荧光激活细胞分选，FACS）中的肌红蛋白抗病毒蛋白 A（MxA），作为 I 型 IFN 活性的潜在生物标志物。此外，使用 FACS 同时分析 CD14 单核细胞中的潜在生物标志物，如 CD64、CD169 和 B 细胞激活因子（BAFF）。通过实时定量 PCR 测定 CD14 单核细胞中 IFN I 型特征基因（IFI44、IFI44L、IFIT3、LY6E 和 MX1）的表达值，计算总 IFN I 型生物活性的 IFN 评分。
IFN 评分与单核细胞 MxA 蛋白（r=0.741，p<0.001）和全血 MxA 水平（r=0.764，p<0.001）相关性最强，与 CD169（r=0.495，p<0.001）和 CD64（r=0.436，p=0.007）相关性较弱，与 BAFF 蛋白不相关。全血 MxA 水平与 EULAR 干燥综合征疾病活动指数评分和许多临床 pSS 参数相关。有趣的是，接受羟氯喹治疗的患者 MxA 水平降低（EIA，p=0.04；FACS，p=0.001）。
MxA 测定是评估 pSS 中 IFN I 型活性的极好工具，其中 MxA-EIA 最为实用。MxA 水平与活动性疾病的特征相关，在接受羟氯喹治疗的患者中降低，表明 MxA 在根据 IFN 阳性对患者进行分层方面具有临床适用性。
