Section of Oral and Diagnostic Sciences, Columbia University College of Dental Medicine, 630 W 168 St., P&S Box 20, New York, NY 10032-3725, USA.
Biochem Biophys Res Commun. 2012 Feb 3;418(1):33-7. doi: 10.1016/j.bbrc.2011.12.102. Epub 2011 Dec 27.
The retinal pigment epithelium (RPE) is a barrier to Klebsiella pneumoniae infection in endogenous endophthalmitis. Nevertheless, the inflammatory response of RPE cells upon interaction with this pathogen has not been studied. Here we tested the hypothesis that K. pneumoniae induces an inflammatory response in human retinal epithelial cells.
In this study we set out to investigate the effects of whole K. pneumoniae and of its lipopolysaccharide on RPE cells in vitro using bacterial invasion and cytotoxicity assays, fluorescent microscopy and ELISA. For that, we utilized K. pneumoniae strain ATCC 43816 and the continuous human retinal-pigmented epithelial cell line ARPE-19.
Stimulation of ARPE-19 with live K. pneumoniae for 24h induced a 31.5-fold (p=0.0132) increase in IL-6 and 6.5-fold (p=0.0004) increase in MCP-1 levels compared to the non-infected control cells. Purified K. pneumoniae LPS (1μgml(-1)) also induced cytokine levels, MCP-1 (1.7-fold upregulation; p=0.0006) and IL-6 (1.3-fold upregulation, p=0.065). The tested K. pneumoniae strain ATCC 43816 did not have a significant effect on the viability of ARPE-19 cells (11% decrease, p=0.096) and showed a low ability to invade the cells.
Both whole live K. pneumoniae and K. pneumoniae LPS exert a strong pro-inflammatory effect on retinal pigmented epithelial cells, consistent with clinical manifestations of disease. Bacterial pro-inflammatory effects are not likely related to host cell invasion. This is the first investigation of the interactions of a major endogenous endophthalmitis pathogen, K. pneumoniae with human retinal pigmented epithelial cells.
在眼内源性内源性眼内炎中，视网膜色素上皮（RPE）是一种阻止肺炎克雷伯氏菌感染的屏障。然而，RPE 细胞与这种病原体相互作用时的炎症反应尚未得到研究。在这里，我们检验了肺炎克雷伯氏菌会在人视网膜上皮细胞中引起炎症反应的假设。
在这项研究中，我们使用细菌入侵和细胞毒性测定、荧光显微镜和 ELISA 法，在体外研究了整个肺炎克雷伯氏菌及其脂多糖对 RPE 细胞的影响。为此，我们利用肺炎克雷伯氏菌菌株 ATCC 43816 和连续的人视网膜色素上皮细胞系 ARPE-19。
用活的肺炎克雷伯氏菌刺激 ARPE-19 24 小时后，与未感染对照细胞相比，IL-6 增加了 31.5 倍（p=0.0132），MCP-1 增加了 6.5 倍（p=0.0004）。纯化的肺炎克雷伯氏菌 LPS（1μgml(-1)）也诱导了细胞因子水平，MCP-1（上调 1.7 倍；p=0.0006）和 IL-6（上调 1.3 倍，p=0.065）。测试的肺炎克雷伯氏菌菌株 ATCC 43816 对 ARPE-19 细胞的活力没有显著影响（减少 11%，p=0.096），并且显示出低的细胞入侵能力。
整个活的肺炎克雷伯氏菌和肺炎克雷伯氏菌 LPS 对视网膜色素上皮细胞都具有很强的促炎作用，与疾病的临床表现一致。细菌的促炎作用可能与宿主细胞的入侵无关。这是对主要的眼内源性内源性眼内炎病原体肺炎克雷伯氏菌与人视网膜色素上皮细胞相互作用的首次研究。
