Department of Genetics, Biology and Biochemistry, University of Torino Medical School, Turin, Italy.
Infect Immun. 2010 Nov;78(11):4912-21. doi: 10.1128/IAI.00455-10. Epub 2010 Aug 23.
Hemozoin (HZ)-fed monocytes are exposed to strong oxidative stress, releasing large amounts of peroxidation derivatives with subsequent impairment of numerous functions and overproduction of proinflammatory cytokines. However, the histopathology at autopsy of tissues from patients with severe malaria showed abundant HZ in Kupffer cells and other tissue macrophages, suggesting that functional impairment and cytokine production are not accompanied by cell death. The aim of the present study was to clarify the role of HZ in cell survival, focusing on the qualitative and temporal expression patterns of proinflammatory and antiapoptotic molecules. Immunocytochemical and flow cytometric analyses showed that the long-term viability of human monocytes was unaffected by HZ. Short-term analysis by macroarray of a complete panel of cytokines and real-time reverse transcription (RT)-PCR experiments showed that HZ immediately induced interleukin-1β (IL-1β) gene expression, followed by transcription of eight additional chemokines (IL-8, epithelial cell-derived neutrophil-activating peptide 78 [ENA-78], growth-regulated oncogene α [GROα], GROβ, GROγ, macrophage inflammatory protein 1α [MIP-1α], MIP-1β, and monocyte chemoattractant protein 1 [MCP-1]), two cytokines (tumor necrosis factor alpha [TNF-α] and IL-1receptor antagonist [IL-1RA]), and the cytokine/chemokine-related proteolytic enzyme matrix metalloproteinase 9 (MMP-9). Furthermore, real-time RT-PCR showed that 15-HETE, a potent lipoperoxidation derivative generated by HZ through heme catalysis, recapitulated the effects of HZ on the expression of four of the chemokines. Intermediate-term investigation by Western blotting showed that HZ increased expression of HSP27, a chemokine-related protein with antiapoptotic properties. Taken together, the present data suggest that apoptosis of HZ-fed monocytes is prevented through a cascade involving 15-HETE-mediated upregulation of IL-1β transcription, rapidly sustained by chemokine, TNF-α, MMP-9, and IL-1RA transcription and upregulation of HSP27 protein expression.
疟原虫血红素（HZ）喂养的单核细胞暴露于强烈的氧化应激下，会释放大量的过氧化衍生物，从而损害许多功能并导致促炎细胞因子过度产生。然而，对重症疟疾患者组织的尸检组织病理学显示，库普弗细胞和其他组织巨噬细胞中含有大量的 HZ，这表明功能障碍和细胞因子产生并不伴随着细胞死亡。本研究旨在阐明 HZ 在细胞存活中的作用，重点研究促炎和抗凋亡分子的定性和时间表达模式。免疫细胞化学和流式细胞术分析表明，HZ 对人单核细胞的长期存活没有影响。通过微阵列对细胞因子的全面分析和实时逆转录（RT）-PCR 实验表明，HZ 可立即诱导白细胞介素-1β（IL-1β）基因表达，随后转录另外 8 种趋化因子（IL-8、上皮细胞衍生的中性粒细胞激活肽 78 [ENA-78]、生长调节癌基因α[GROα]、GROβ、GROγ、巨噬细胞炎性蛋白 1α[MIP-1α]、MIP-1β和单核细胞趋化蛋白 1[MCP-1]）、2 种细胞因子（肿瘤坏死因子α[TNF-α]和白细胞介素-1 受体拮抗剂[IL-1RA]）和细胞因子/趋化因子相关的蛋白水解酶基质金属蛋白酶 9（MMP-9）。此外，实时 RT-PCR 表明，HZ 通过血红素催化生成的一种强有力的脂过氧化衍生物 15-HETE，可重现 HZ 对 4 种趋化因子表达的影响。通过 Western blot 进行的中期研究表明，HZ 增加了 HSP27 的表达，HSP27 是一种具有抗凋亡特性的趋化因子相关蛋白。综上所述，本研究数据表明，15-HETE 介导的 IL-1β 转录上调引发的级联反应可防止 HZ 喂养的单核细胞凋亡，该级联反应可迅速维持趋化因子、TNF-α、MMP-9 和 IL-1RA 转录以及 HSP27 蛋白表达的上调。
