Małopolska Centre of Biotechnology, Jagiellonian University, Kraków, Poland; Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
Redox Biol. 2020 Jul;34:101566. doi: 10.1016/j.redox.2020.101566. Epub 2020 May 12.
Divalent copper and iron cations have been acknowledged for their catalytic roles in physiological processes critical for homeostasis maintenance. Being redox-active, these metals act as cofactors in the enzymatic reactions of electron transfer. However, under pathophysiological conditions, owing to their high redox potentials, they may exacerbate stress-induced injury. This could be particularly hazardous to the liver - the main body reservoir of these two metals. Surprisingly, the involvement of Cu and Fe in liver pathology still remains poorly understood. Hypoxic stress in the tissue may act as a stimulus that mobilizes these ions from their hepatic stores, aggravating the systemic injury. Since ischemia poses a serious complication in liver surgery (e.g. transplantation) we aimed to reveal the status of Cu and Fe via spectroscopic analysis of mouse ischemic liver tissue. Herein, we establish a novel non-surgical model of focal liver ischemia, achieved by applying light locally when a photosensitizer is administered systemically. Photodynamic treatment results in clear-cut areas of the ischemic hepatic tissue, as confirmed by ultrasound scans, mean velocity measurements, 3D modelling of vasculature and (immuno)histological analysis. For reference, we assessed the samples collected from the animals which developed transient systemic endotoxemic stress induced by a non-lethal dose of lipopolysaccharide. The electron paramagnetic resonance (EPR) spectra recorded in situ in the liver samples reveal a dramatic increase in the level of Cu adducts solely in the ischemic tissues. In contrast, other typical free radical components of the liver EPR spectra, such as reduced Riske clusters are not detected; these differences are not followed by changes in the blood EPR spectra. Taken together, our results suggest that local ischemic stress affects paramagnetic species containing redox-active metals. Moreover, because in our model hepatic vascular flow is impaired, these effects are only local (confined to the liver) and are not propagated systemically.
二价铜和铁阳离子已被确认为在维持体内平衡的生理过程中具有催化作用。由于具有氧化还原活性，这些金属在电子转移的酶反应中充当辅助因子。然而，在病理生理条件下，由于其高氧化还原电位，它们可能会加剧应激诱导的损伤。这对肝脏尤其危险-这两种金属的主要储存库。令人惊讶的是，Cu 和 Fe 参与肝脏病理学的情况仍然知之甚少。组织中的缺氧应激可能是一种刺激，它会从肝脏储存中动员这些离子，从而加剧全身损伤。由于缺血是肝脏手术（例如移植）的严重并发症，我们旨在通过对缺血小鼠肝脏组织进行光谱分析来揭示 Cu 和 Fe 的状况。在这里，我们通过在全身给予光敏剂时局部施加光来建立一种新的非手术性局灶性肝缺血模型。光动力治疗导致缺血性肝组织的明确区域，如超声扫描、平均速度测量、血管的 3D 建模和（免疫）组织学分析所证实。作为参考，我们评估了从动物身上收集的样本，这些动物因非致死剂量的脂多糖引起短暂的全身内毒素应激。在原位记录的肝脏样本的电子顺磁共振（EPR）谱仅在缺血组织中显示 Cu 加合物的水平急剧增加。相比之下，没有检测到其他典型的肝脏 EPR 谱的自由基成分，例如还原的 Riske 簇；这些差异在血液 EPR 谱中没有变化。总之，我们的结果表明，局部缺血应激会影响含有氧化还原活性金属的顺磁物质。此外，由于在我们的模型中肝脏血管血流受损，这些影响仅在局部（局限于肝脏），不会在系统中传播。
