Sampey A V, Hall P H, Mitchell R A, Metz C N, Morand E F
Monash University Department of Medicine, Melbourne, Australia.
Arthritis Rheum. 2001 Jun;44(6):1273-80. doi: 10.1002/1529-0131(200106)44:6<1273::AID-ART219>3.0.CO;2-8.
Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine with known actions in macrophage and T cell activation. MIF also has the unique capacity to reverse the inhibitory effects of glucocorticoids on these cells. We have recently demonstrated MIF expression in human rheumatoid arthritis (RA) synovium and cultured fibroblast-like synoviocytes (FLS), as well as the ability of FLS-derived MIF to induce monocyte release of tumor necrosis factor alpha. We investigated the effects of MIF on aspects of RA FLS activation, including the induction of phospholipase A2 (PLA2) and cyclooxygenase (COX).
PLA2 activity was measured by 3H-arachidonic acid released from treated FLS supernatants. COX activity was measured by prostaglandin E2 enzyme-linked immunosorbent assay. Cytosolic PLA2 (cPLA2) and COX-2 messenger RNA (mRNA) were determined using semiquantitative reverse transcriptase-polymerase chain reaction.
Constitutive PLA2 activity was detected in RA FLS. Recombinant human MIF up-regulated PLA2 activity (P < 0.01) and cPLA2 mRNA expression, but had no effect on secretory PLA2. Recombinant human MIF up-regulated COX activity (P < 0.05) and COX-2 mRNA, but had no observable effect on COX-1. Interleukin-1beta (IL-1beta) significantly up-regulated PLA2 activity (P < 0.005) and cPLA2 mRNA expression while anti-MIF monoclonal antibody (mAb) significantly inhibited this IL-1beta-induced PLA2 activity (P < 0.02). Anti-MIF mAb significantly reduced IL-1beta-induced COX activity (P < 0.05) and COX-2 mRNA expression.
MIF exerts a proinflammatory effect on key aspects of RA FLS activation. That anti-MIF mAb inhibited IL-1beta up-regulation of FLS indicates an additional cofactor role for MIF in IL-1beta-induced FLS activation. These data suggest that MIF antagonism has important therapeutic potential in RA.
巨噬细胞移动抑制因子（MIF）是一种促炎细胞因子，在巨噬细胞和T细胞激活中具有已知作用。MIF还具有独特的能力，可逆转糖皮质激素对这些细胞的抑制作用。我们最近证明了MIF在人类类风湿性关节炎（RA）滑膜和培养的成纤维样滑膜细胞（FLS）中的表达，以及FLS衍生的MIF诱导单核细胞释放肿瘤坏死因子α的能力。我们研究了MIF对RA FLS激活各方面的影响，包括磷脂酶A2（PLA2）和环氧化酶（COX）的诱导。
通过从处理过的FLS上清液中释放的3H-花生四烯酸来测量PLA2活性。通过前列腺素E2酶联免疫吸附测定法测量COX活性。使用半定量逆转录聚合酶链反应测定胞质型PLA2（cPLA2）和COX-2信使核糖核酸（mRNA）。
在RA FLS中检测到组成型PLA2活性。重组人MIF上调了PLA2活性（P < 0.01）和cPLA2 mRNA表达，但对分泌型PLA2没有影响。重组人MIF上调了COX活性（P < 0.05）和COX-2 mRNA，但对COX-1没有明显影响。白细胞介素-1β（IL-1β）显著上调了PLA2活性（P < 0.005）和cPLA2 mRNA表达，而抗MIF单克隆抗体（mAb）显著抑制了这种IL-1β诱导的PLA2活性（P < 0.02）。抗MIF mAb显著降低了IL-1β诱导的COX活性（P < 0.05）和COX-2 mRNA表达。
MIF对RA FLS激活的关键方面发挥促炎作用。抗MIF mAb抑制IL-1β对FLS的上调表明MIF在IL-1β诱导的FLS激活中具有额外的辅助因子作用。这些数据表明MIF拮抗作用在RA中具有重要的治疗潜力。
