Altered responsiveness to extracellular ATP enhances acetaminophen hepatotoxicity.
Altered responsiveness to extracellular ATP enhances acetaminophen hepatotoxicity.
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对细胞外ATP的反应改变会增强对乙酰氨基酚肝毒性。
DOI：
10.1186/1478-811x-11-10
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发表时间：
2013-02-05
期刊：
影响因子：
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通讯作者：
Menezes GB
中科院分区：
文献类型：
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作者：
Amaral SS;Oliveira AG;Marques PE;Quintão JL;Pires DA;Resende RR;Sousa BR;Melgaço JG;Pinto MA;Russo RC;Gomes AK;Andrade LM;Zanin RF;Pereira RV;Bonorino C;Soriani FM;Lima CX;Cara DC;Teixeira MM;Leite MF;Menezes GB
三磷酸腺苷（ATP）在生理条件下由肝细胞分泌，并通过激活P2受体在肝脏生物学中发挥重要作用。相反，在坏死期间观察到的较高的细胞外ATP浓度触发炎症反应，导致肝损伤的进展。钙（Ca2+）稳态受损是对乙酰氨基酚（APAP）诱导的肝毒性的标志，由于ATP诱导细胞内Ca2+储备的动员，我们评估了在APAP诱导的坏死过程中ATP的释放是否直接导致肝细胞死亡。APAP过量导致肝坏死、大量中性粒细胞浸润和大的非灌注区域，以及远端肺部炎症。在肝脏中，通过腺苷三磷酸双磷酸酶或P2X受体阻断进行ATP代谢后，这些作用显著消除，但没有一种治疗可以预防远端肺部炎症，表明嘌呤能信号传导对肝脏环境的局部贡献有限。在体外，APAP给药至原代小鼠肝细胞和HepG2细胞以剂量依赖性方式引起细胞死亡。有趣的是，HepG2细胞暴露于APAP引起ATP显著释放到上清液中，其水平高到足以促进对健康原代肝细胞或HepG2细胞的直接细胞毒性。与我们的体内结果一致，腺苷三磷酸双磷酸酶处理或阻断P2受体降低了APAP细胞毒性。同样，ATP暴露引起APAP处理的原代肝细胞中显著更高的细胞内Ca 2+信号，这在HepG2细胞中再现。定量真实的时间PCR显示APAP攻击的HepG2细胞表达更高水平的几种嘌呤能受体，这可能解释了对细胞外ATP的敏感性。这种表型在分析诊断为急性肝衰竭患者的肝活检中得到证实。我们认为，在病理条件下，ATP不仅可以作为免疫系统激活剂，但也作为旁分泌直接细胞毒性DAMP通过失调的Ca 2+稳态。
Adenosine triphosphate (ATP) is secreted from hepatocytes under physiological conditions and plays an important role in liver biology through the activation of P2 receptors. Conversely, higher extracellular ATP concentrations, as observed during necrosis, trigger inflammatory responses that contribute to the progression of liver injury. Impaired calcium (Ca2+) homeostasis is a hallmark of acetaminophen (APAP)-induced hepatotoxicity, and since ATP induces mobilization of the intracellular Ca2+ stocks, we evaluated if the release of ATP during APAP-induced necrosis could directly contribute to hepatocyte death. APAP overdose resulted in liver necrosis, massive neutrophil infiltration and large non-perfused areas, as well as remote lung inflammation. In the liver, these effects were significantly abrogated after ATP metabolism by apyrase or P2X receptors blockage, but none of the treatments prevented remote lung inflammation, suggesting a confined local contribution of purinergic signaling into liver environment. In vitro, APAP administration to primary mouse hepatocytes and also HepG2 cells caused cell death in a dose-dependent manner. Interestingly, exposure of HepG2 cells to APAP elicited significant release of ATP to the supernatant in levels that were high enough to promote direct cytotoxicity to healthy primary hepatocytes or HepG2 cells. In agreement to our in vivo results, apyrase treatment or blockage of P2 receptors reduced APAP cytotoxicity. Likewise, ATP exposure caused significant higher intracellular Ca2+ signal in APAP-treated primary hepatocytes, which was reproduced in HepG2 cells. Quantitative real time PCR showed that APAP-challenged HepG2 cells expressed higher levels of several purinergic receptors, which may explain the hypersensitivity to extracellular ATP. This phenotype was confirmed in humans analyzing liver biopsies from patients diagnosed with acute hepatic failure. We suggest that under pathological conditions, ATP may act not only an immune system activator, but also as a paracrine direct cytotoxic DAMP through the dysregulation of Ca2+ homeostasis.