HOCl-induced lysophospholipid generation from diacyl- and alkenyl-acyl-phospholipids

炎症过程在许多疾病中起着非常重要的作用。在分子水平上，炎症过程的特征是典型的炎症细胞（如中性粒细胞）从血流侵入炎症组织。这些细胞（除了其他化合物）产生活性氧（ROS），例如HOCl。由于生物样品总是含有大量的磷脂（PLs），它们的ros诱导氧化产物具有明确的生理相关性。在磷脂酰胆碱（PC）的不饱和脂肪酰基残基上加入HOCl，经过几个步骤生成溶血磷脂酰胆碱（LPC）。溶血磷脂（LPLs），特别是LPCs，作为潜在的疾病生物标志物被越来越多地讨论。由于不同物种的PLs在很大程度上是相同的，因此LPLs将代表一种通用的生物标志物（与蛋白质相反）。在上一个资助期，研究了顺式或反式双键的位置对PLs与HOCl反应的影响，特别是确定了LPC的产率。一个主要的方面也是烯基- pls（缩醛原）的氧化行为，因为这些化合物对氧化非常敏感。双键位置的显著影响是显而易见的。值得注意的是，反式异构体对氧化的敏感性低于顺式异构体。另一个重要的结果是，如果在生理盐浓度存在的情况下进行反应，羟基自由基（由Fenton反应产生）也会导致氯丙烷生成。这些影响的原因将通过现代质谱和核磁共振方法进一步详细研究，由此确定的产物的体内相关性将是另一个重要方面。除了游离脂肪酸氧化的产物外，目前还没有得到的磷脂也将被合成（通过化学酶的方法），它们的氧化产物必须被识别。除了这些简化的模型实验外，还将在更高的复杂性水平上研究PLs的化学反应。一方面，必须研究脂质氧化产物（如双键断裂产生的醛）与其他丰富分子（如蛋白质）之间的反应。另一方面，LPLs在生物体中不仅通过氧化产生，而且在磷脂酶A2 （PLA2）的影响下产生。因此，必须研究氧化的PLs是否被PLA2切割到与未氧化的PLs相同的程度，或者酶是否被氧化官能团的存在（部分）抑制。最后，将证明体外检测到的氧化产物是否也可在组织切片中检测到，即在高度复杂的生物基质中。这些调查将由MALDI-MS-Imaging与明尼苏达大学合作进行。

Inflammatory processes play extraordinarily important roles in many diseases. On the molecular level inflammatory processes are characterized by the invasion of typical inflammatory cells (such as neutrophilic granulocytes) from the blood stream into the inflamed tissue. These cells generate (beside other compounds) reactive oxygen species (ROS), for instance, HOCl. As biological samples contain always major amounts of phospholipids (PLs), their ROS-induced oxidation products possess unequivocally physiological relevance. The addition of HOCl to the unsaturated fatty acyl residues of phosphatidylcholine (PC) leads in several steps to the generation of lysophosphatidylcholine (LPC). Lysophospholipids (LPLs), particularly LPCs, are increasingly discussed as potential disease biomarkers. As PLs of different species are widely identical, LPLs would represent (in contrast to proteins) a universal biomarker. In the last funding period the influence of the positions of the double bonds with either cis or trans configuration on the reaction of PLs with HOCl were investigated and particularly the yield of LPC determined. One major aspect was also the oxidation behavior of alkenyl-PLs (plasmalogens), as these compounds are very sensitive to oxidation. A significant influence of the position of the double bond is evident. Remarkably, the trans isomers are less sensitive to oxidation than the cis-isomers. Another important result was that hydroxyl radicals (generated by the Fenton reaction) do also result in chlorohydrin generation if the reaction is performed in the presence of physiological salt concentration. The reasons for these effects are to be further investigated in more detail by modern MS and NMR methods, whereby the in vivo relevance of the identified products will be another important aspect. Beside the products of free fatty acid oxidation, the so far unavailable phospholipids are to be synthesized (by a chemoenzymatic approach) and their oxidation products have to be identified. In addition to these simplified model experiments chemical reactions of PLs will also be studied at a higher complexity level. On the one hand, the reactions between lipid oxidation products (e.g. aldehydes generated by the cleavage of the double bond) and other abundant molecules (e.g. proteins) must be studied. On the other hand, LPLs are generated in the organism not only by oxidation but as well under the influence of the enzyme phospholipase A2 (PLA2). Therefore, it must be investigated if oxidized PLs are cleaved to the same extent by PLA2 (as the non-oxidized PLs) or if the enzyme is (partially) inhibited by the presence of oxidized functional groups. Finally, it will be proven whether the in vitro detected oxidation products are also detectable in tissue slices, i.e. within a highly complex biological matrix. These investigations will be carried out by MALDI-MS-Imaging in cooperation with the University of Münster.