Otero Miguel, Gomez Reino Juan Jesús, Gualillo Oreste
Hospital Clinico Universitario de Santiago, Santiago de Compostela, Spain.
Arthritis Rheum. 2003 Feb;48(2):404-9. doi: 10.1002/art.10811.
To study, in vitro, the effect of leptin (OB), alone or in combination with interferon-gamma (IFNgamma), on inducible nitric oxide synthase (iNOS) and NO production in human primary chondrocytes and in mouse embryonic chondrogenic ATDC5 cells.
Leptin receptor expression and iNOS messenger RNA expression were evaluated by reverse transcriptase-polymerase chain reaction. Then, iNOS activity was indirectly studied by measuring nitrite accumulation, using the Griess colorimetric reaction, in culture medium of human primary chondrocytes and ATDC5 cells.
ATDC5 mouse embryonic cells expressed functional OB receptor. Alone, neither OB nor IFNgamma produced nitrite accumulation in culture medium. However, costimulation with OB and IFNgamma resulted in dose-dependent up-regulation of the expression of iNOS and NO production in human primary chondrocytes and ATDC5 cells. Production of NO was blunted by the iNOS-specific inhibitors L-N(G)-nitroarginine methyl ester and aminoguanidine. In addition, the janus-activated kinase 2 (JAK2)-specific inhibitor Tyrphostin AG 490 completely blocked OB + IFNgamma-driven up-regulation of iNOS and NO production.
Our data show for the first time a putative proinflammatory role of OB via iNOS induction and NO production. This occurs via activation of JAK2.
在体外研究瘦素（OB）单独或与γ干扰素（IFNγ）联合对人原代软骨细胞和小鼠胚胎软骨生成ATDC5细胞中诱导型一氧化氮合酶（iNOS）及一氧化氮（NO）产生的影响。
通过逆转录聚合酶链反应评估瘦素受体表达及iNOS信使核糖核酸表达。然后，利用格里斯比色法，通过检测人原代软骨细胞和ATDC5细胞培养基中的亚硝酸盐积累，间接研究iNOS活性。
ATDC5小鼠胚胎细胞表达功能性OB受体。单独使用时，OB和IFNγ均未使培养基中亚硝酸盐积累。然而，OB与IFNγ共同刺激导致人原代软骨细胞和ATDC5细胞中iNOS表达及NO产生呈剂量依赖性上调。iNOS特异性抑制剂L-N(G)-硝基精氨酸甲酯和氨基胍可抑制NO的产生。此外，Janus激活激酶2（JAK2）特异性抑制剂酪氨酸磷酸化抑制剂AG 490完全阻断了OB + IFNγ驱动的iNOS上调及NO产生。
我们的数据首次表明OB可能通过诱导iNOS和产生NO发挥促炎作用。这是通过激活JAK2发生的。
