Institute of Biotechnology, National Ilan University, Ilan, Taiwan.
Inflamm Res. 2012 Oct;61(10):1107-16. doi: 10.1007/s00011-012-0503-1. Epub 2012 Jun 16.
Although several mechanisms by which hyperglycemia modulate inflammation have been proposed, it remains unclear how hyperglycemia regulates inflammation induced by lipopolysaccharide (LPS).
We hypothesized that hyperglycemia might interplay with LPS to modulate the generation of an inflammatory mediator. RAW 264.7 macrophages cultured in medium containing either normal glucose (5.5-mM) or high glucose (HG) (15- and 25-mM) were treated with LPS. The nitric oxide (NO) generation, inducible NO synthase (iNOS) expression and cytokine release were then quantified by Griess reaction, western blot, and enzyme-linked immunosorbent assay (ELISA) respectively. The effect of HG on the activation of kinase and Nuclear Factor-Kappa B (NF-κB) were measured by western blot and NF-κB reporter assay respectively.
Without LPS stimulation, HG alone did not induce NO generation and cytokine secretion; but LPS-induced NO generation, iNOS expression, and interleukin-1beta (IL-1β) secretion were higher in HG-cultured cells than in normal glucose-cultured cells. In contrast, LPS-induced interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) secretion were lower in HG-cultured cells than in normal glucose-cultured cells. Furthermore, HG increased iNOS expression and NO generation by enhancing phosphorylation levels of protein kinase C-alpha (PKC-α), protein kinase C-delta (PKC-δ), and p38 phosphorylation and NF-κB transcriptional activity.
This study revealed a possible role of PKC-α and PKC-δ potentially involved in diabetes-promoted inflammation.
尽管已经提出了几种高血糖调节炎症的机制，但高血糖如何调节脂多糖（LPS）诱导的炎症仍不清楚。
我们假设高血糖可能与 LPS 相互作用调节炎症介质的产生。在含有正常葡萄糖（5.5mM）或高葡萄糖（HG）（15mM 和 25mM）的培养基中培养 RAW 264.7 巨噬细胞，用 LPS 处理。然后通过格里斯反应、western blot 和酶联免疫吸附测定（ELISA）分别定量测定一氧化氮（NO）生成、诱导型一氧化氮合酶（iNOS）表达和细胞因子释放。通过 western blot 和 NF-κB 报告基因测定分别测定 HG 对激酶和核因子-κB（NF-κB）激活的影响。
在没有 LPS 刺激的情况下，HG 单独不会诱导 NO 生成和细胞因子分泌；但 LPS 诱导的 NO 生成、iNOS 表达和白细胞介素-1β（IL-1β）分泌在 HG 培养的细胞中高于正常葡萄糖培养的细胞。相比之下，LPS 诱导的白细胞介素-6（IL-6）和肿瘤坏死因子-α（TNF-α）分泌在 HG 培养的细胞中低于正常葡萄糖培养的细胞。此外，HG 通过增强蛋白激酶 C-α（PKC-α）、蛋白激酶 C-δ（PKC-δ）和 p38 磷酸化以及 NF-κB 转录活性，增加 iNOS 表达和 NO 生成。
本研究揭示了 PKC-α 和 PKC-δ 在糖尿病促进炎症中可能发挥作用。
