Litherland S A, Xie T X, Grebe K M, Davoodi-Semiromi A, Elf J, Belkin N S, Moldawer L L, Clare-Salzler M J
Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, 100275 JHMHC, 1600 SW Archer Road, Gainesville, FL 32610, USA.
J Autoimmun. 2005 Jun;24(4):297-310. doi: 10.1016/j.jaut.2005.02.001. Epub 2005 Mar 23.
Autocrine granulocyte macrophage-colony stimulating factor (GM-CSF) sequentially activates intracellular components in monocyte/macrophage production of the pro-inflammatory and immunoregulatory prostanoid, prostaglandin E2 (PGE2). GM-CSF first induces STAT5 signaling protein phosphorylation, then prostaglandin synthase 2 (COX2/PGS2) gene expression, and finally IL-10 production, to downregulate the cascade. Without activation, monocytes of at-risk, type 1 diabetic (T1D), and autoimmune thyroid disease (AITD) humans, and macrophages of nonobese diabetic (NOD) mice have aberrantly high GM-CSF, PGS2, and PGE2 expression, but normal levels of IL-10. After GM-CSF stimulation, repressor STAT5A and B isoforms (80-77kDa) in autoimmune human and NOD monocytes and activator STAT5A (96-94kDa) and B (94-92kDa) isoforms in NOD macrophages stay persistently tyrosine phosphorylated. This STAT5 phosphorylation persisted despite treatment in vitro with IL-10, anti-GM-CSF antibody, or the JAK2/3 inhibitor, AG490. Phosphorylated STAT5 repressor isoforms in autoimmune monocytes had diminished DNA binding capacity on GAS sequences found in the PGS2 gene enhancer. In contrast, STAT5 activator isoforms in NOD macrophages retained their DNA binding capacity on these sites much longer than in healthy control strain macrophages. These findings suggest that STAT5 dysfunction may contribute to dysregulation of GM-CSF signaling and gene activation, including PGS2, in autoimmune monocytes and macrophages.
自分泌粒细胞巨噬细胞集落刺激因子（GM-CSF）在单核细胞/巨噬细胞产生促炎和免疫调节前列腺素E2（PGE2）的过程中依次激活细胞内成分。GM-CSF首先诱导信号转导和转录激活因子5（STAT5）信号蛋白磷酸化，然后诱导前列腺素合酶2（COX2/PGS2）基因表达，最后诱导白细胞介素10（IL-10）产生，从而下调该级联反应。在未激活的情况下，有患病风险的1型糖尿病（T1D）患者和自身免疫性甲状腺疾病（AITD）患者的单核细胞，以及非肥胖糖尿病（NOD）小鼠的巨噬细胞中，GM-CSF、PGS2和PGE2的表达异常高，但IL-10水平正常。GM-CSF刺激后，自身免疫患者和NOD单核细胞中的抑制性STAT5A和B亚型（80 - 77 kDa）以及NOD巨噬细胞中的激活型STAT5A（96 - 94 kDa）和B（94 - 92 kDa）亚型持续保持酪氨酸磷酸化。尽管在体外使用IL-10、抗GM-CSF抗体或JAK2/3抑制剂AG490进行处理，这种STAT5磷酸化仍持续存在。自身免疫单核细胞中磷酸化的STAT5抑制亚型在PGS2基因增强子中发现的GAS序列上的DNA结合能力减弱。相比之下，NOD巨噬细胞中的STAT5激活亚型在这些位点上保持其DNA结合能力的时间比健康对照品系巨噬细胞长得多。这些发现表明，STAT5功能障碍可能导致自身免疫单核细胞和巨噬细胞中GM-CSF信号传导和基因激活失调，包括PGS2。
