Smith Judith A, Barnes Michael D, Hong Dihua, DeLay Monica L, Inman Robert D, Colbert Robert A
Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA.
Arthritis Rheum. 2008 Jun;58(6):1640-9. doi: 10.1002/art.23512.
To determine whether macrophages, a type of cell implicated in the pathogenesis of ankylosing spondylitis (AS), exhibit a characteristic gene expression pattern.
Macrophages were derived from the peripheral blood of 8 AS patients (median disease duration 13 years [range <1-43 years]) and 9 healthy control subjects over 7 days with the use of granulocyte-macrophage colony-stimulating factor. Cells were stimulated for 24 hours with interferon-gamma (IFN gamma; 100 units/ml), were left untreated for 24 hours, or were treated for 3 hours with lipopolysaccharide (LPS; 10 ng/ml). RNA was isolated and examined by microarray and real-time quantitative reverse transcription-polymerase chain reaction analysis.
Microarray analysis revealed 198 probe sets detecting the differential expression of 141 unique genes in untreated macrophages from AS patients compared with healthy controls. Clustering and principal components analysis clearly distinguished AS patients and controls. Of the differentially expressed genes, 78 (55%) were IFN-regulated, and their relative expression indicated a "reverse" IFN signature in AS patient macrophages, where IFN gamma-up-regulated genes were underexpressed and down-regulated genes were overexpressed. Treatment of macrophages with exogenous IFN gamma normalized the expression of these genes between patients and controls. In addition, the messenger RNA encoded by the IFN gamma gene was approximately 2-fold lower in AS patient macrophages at baseline (P = 0.004) and was poorly responsive to LPS (P = 0.018), as compared with healthy controls.
Our findings reveal consistent differences in gene expression in macrophages from AS patients, with evidence of a striking "reverse" IFN signature. Together with poor expression and responsiveness of the IFN gamma gene, these results suggest that there may be a relative defect in IFN gamma gene regulation, with autocrine consequences and implications for disease pathogenesis.
确定巨噬细胞（一种与强直性脊柱炎（AS）发病机制相关的细胞类型）是否呈现出特征性的基因表达模式。
使用粒细胞巨噬细胞集落刺激因子，从8例AS患者（疾病中位病程13年[范围<1 - 43年]）和9名健康对照者的外周血中分离巨噬细胞，培养7天。细胞分别用γ干扰素（IFNγ；100单位/ml）刺激24小时、不进行处理24小时或用脂多糖（LPS；10 ng/ml）处理3小时。分离RNA并通过微阵列和实时定量逆转录聚合酶链反应分析进行检测。
微阵列分析显示，与健康对照相比，在未处理的AS患者巨噬细胞中有198个探针集检测到141个独特基因的差异表达。聚类和主成分分析清楚地区分了AS患者和对照。在差异表达的基因中，78个（55%）受IFN调节，它们的相对表达表明AS患者巨噬细胞中存在“反向”IFN特征，即IFNγ上调的基因表达不足，而下调的基因表达过度。用外源性IFNγ处理巨噬细胞可使患者和对照之间这些基因的表达正常化。此外，与健康对照相比，AS患者巨噬细胞中IFNγ基因编码的信使RNA在基线时约低2倍（P = 0.004），且对LPS反应较差（P = 0.018）。
我们的研究结果揭示了AS患者巨噬细胞基因表达存在一致差异，有明显“反向”IFN特征的证据。连同IFNγ基因表达和反应性较差，这些结果表明IFNγ基因调控可能存在相对缺陷，具有自分泌后果并对疾病发病机制有影响。
