Singh Purnima, Castillo Alexander, Majid Dewan S A
Department of Physiology, Hypertension & Renal Center of Excellence, Tulane University Health Sciences Center, New Orleans, 70112, Louisiana.
Physiol Rep. 2014 Feb 10;2(2):e00228. doi: 10.1002/phy2.228. eCollection 2014 Feb 1.
Earlier, we demonstrated that the inhibition of nitric oxide synthase (NOS) by nitro-l-arginine methyl ester (l-NAME) infusion increases the endogenous production of proinflammatory cytokine, tumor necrosis factor (TNF-α). In the present study, we examined the hypothesis that inhibition of nitric oxide (NO) production leads to the suppression of interleukin (IL)-10 (anti-inflammatory cytokine) generation which facilitates the enhancement of TNF-α production endogenously. Using appropriate enzyme-linked immunosorbent assay kits and immunohistochemical staining, the levels of IL-10 and TNF-α in plasma (P) and in renal tissues (R) were measured in anesthetized mice (C57BL/6; ~10 weeks age; n = 6/group) infused with or without l-NAME (200 μg/min/kg; i.v. for 2 h). Compared to vehicle-treated control mice, l-NAME-treated mice had a lower level of IL-10 (P, 0.3 ± 0.1 vs. 2.6 ± 0.6 ng/mL; R, 0.5 ± 0.1 vs. 3 ± 0.1 ng/mg protein) and a higher level of TNF-α (P, 432 ± 82 vs. undetected pg/mL; R, 58 ± 7 vs. 6 ± 5 pg/mg protein). IL-10 protein expression, present mostly in the distal nephron segments in control mice, was markedly downregulated in l-NAME-treated mice. Compared to control mice, TNF-α expression increased 2.5-fold in renal cortical sections (mostly in the distal nephron segments) in l-NAME-treated mice. Coinfusion of a NO donor, S-nitroso-N-acetyl-penicillamine (SNAP; 25 μg/min/kg) with l-NAME in a separate group of mice prevented these changes in IL-10 and TNF-α induced by l-NAME. IL-10 infusion (0.075 ng/min/g) in l-NAME-treated mice markedly attenuated l-NAME-induced increments in TNF-α. Thus, these results demonstrate that NOS inhibition decreases endogenous IL-10 generation and thus, minimizes its immune downregulating action on the TNF-α production in the kidney.
此前，我们证明通过静脉输注硝基-L-精氨酸甲酯（L-NAME）抑制一氧化氮合酶（NOS）可增加促炎细胞因子肿瘤坏死因子（TNF-α）的内源性产生。在本研究中，我们检验了以下假设：抑制一氧化氮（NO）产生会导致白细胞介素（IL）-10（抗炎细胞因子）生成受到抑制，从而促进内源性TNF-α产生的增强。使用合适的酶联免疫吸附测定试剂盒和免疫组织化学染色方法，对麻醉小鼠（C57BL/6；约10周龄；每组n = 6）输注或不输注L-NAME（200μg/分钟/千克；静脉注射2小时）后，检测其血浆（P）和肾组织（R）中IL-10和TNF-α的水平。与溶剂处理的对照小鼠相比，L-NAME处理的小鼠IL-10水平较低（血浆中：0.3±0.1对2.6±0.6 ng/mL；肾组织中：0.5±0.1对3±0.1 ng/mg蛋白质），而TNF-α水平较高（血浆中：432±82对未检测到pg/mL；肾组织中：58±7对6±5 pg/mg蛋白质）。IL-10蛋白表达在对照小鼠中主要存在于远端肾单位节段，在L-NAME处理的小鼠中明显下调。与对照小鼠相比，L-NAME处理的小鼠肾皮质切片（主要在远端肾单位节段）中TNF-α表达增加了2.5倍。在另一组小鼠中，将NO供体S-亚硝基-N-乙酰青霉胺（SNAP；25μg/分钟/千克）与L-NAME共同输注可防止L-NAME诱导的IL-10和TNF-α的这些变化。在L-NAME处理的小鼠中输注IL-10（0.075 ng/分钟/克）可显著减弱L-NAME诱导的TNF-α增加。因此，这些结果表明，抑制NOS会降低内源性IL-10的生成，从而使其对肾脏中TNF-α产生的免疫下调作用最小化。
