Reisch Florian, Schäfer Marjann, Labuz Dominika, Machelska Halina, Stehling Sabine, Püschel Gerhard P, Rothe Michael, Heydeck Dagmar, Kuhn Hartmut
Department of Biochemistry, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt Universität Zu Berlin, Charitéplatz 1, 10117, Berlin, Germany.
Institute for Nutritional Sciences, University Potsdam, Arthur-Scheunert-Allee 114-116, 14558, Nuthetal, Germany.
Cell Mol Biol Lett. 2025 Jul 13;30(1):81. doi: 10.1186/s11658-025-00756-0.
Mammalian arachidonic acid lipoxygenases (ALOXs) have previously been implicated in the pathogenesis of inflammatory disease, and pro- as well as anti-inflammatory activities have been reported. The human genome involves six functional ALOX genes and each of them encodes for a functionally distinct enzyme. ALOX15 is one of these isoforms and the majority of mammalian ALOX15 orthologs including mouse Alox15 convert arachidonic acid to its 12-hydroperoxy derivative. In contrast, human ALOX15 forms 15-hydroperoxy arachidonic acid instead. This difference in the catalytic properties of the two mammalian ALOX15 orthologs may be of biological relevance since arachidonic acid 15-lipoxygenating ALOX-isoforms exhibit an improved biosynthetic capacity for pro-resolving mediators. We recently generated Alox15 knock-in mice, which homozygously express a humanized Alox15 mutant (Leu353Phe) instead of the wildtype enzyme. These animals should be protected from the development of inflammatory symptoms in whole animal inflammation models if the biosynthesis of pro-resolving mediators plays a major role.
To explore whether functional humanization of mouse Alox15 might impact the pathogenesis of inflammatory diseases we tested Alox-KI mice in comparison with wildtype control animals in two whole animal inflammation models (dextran sodium sulfate induced colitis, Freund's complete adjuvant induced paw edema). In these experiments we quantified the severity of inflammatory symptoms during the acute phase of inflammation and during the resolution period.
We found that Alox15 knock-in mice are strongly protected from the development of inflammatory symptoms in the dextran sodium sulfate colitis model when the loss of body weight was used as major readout parameter. Quantification of the colon tissue oxylipidomes revealed that the colon concentrations of resolvin D5 were elevated in Alox15-KI mice and thus, this mediator might contribute to the protective effect induced by our genetic manipulation. However, other specialized pro-resolving mediators, such as maresin-2, neuroprotectin-1, and lipoxins, may not play a major role for the protective response. In the Freund's complete adjuvant induced paw edema inflammation model no protective effect was observed.
Taken together, our data suggest that humanization of the reaction specificity of mouse Alox15 (Leu353Phe mutation) exhibits differential effects in two mouse inflammation models.
哺乳动物花生四烯酸脂氧合酶（ALOXs）先前被认为与炎症性疾病的发病机制有关，并且已报道其具有促炎和抗炎活性。人类基因组包含六个功能性ALOX基因，每个基因编码一种功能不同的酶。ALOX15是其中一种亚型，大多数哺乳动物的ALOX15直系同源物（包括小鼠Alox15）将花生四烯酸转化为其12 - 氢过氧化物衍生物。相比之下，人类ALOX15则形成15 - 氢过氧化物花生四烯酸。这两种哺乳动物ALOX15直系同源物催化特性的差异可能具有生物学意义，因为花生四烯酸15 - 脂氧合的ALOX亚型对促消退介质具有更高的生物合成能力。我们最近培育出了Alox15基因敲入小鼠，这些小鼠纯合表达一种人源化的Alox15突变体（Leu353Phe）而非野生型酶。如果促消退介质的生物合成起主要作用，那么在全动物炎症模型中这些动物应能免受炎症症状的发展。
为探究小鼠Alox15的功能人源化是否会影响炎症性疾病的发病机制，我们在两种全动物炎症模型（葡聚糖硫酸钠诱导的结肠炎和弗氏完全佐剂诱导的爪肿胀）中，将Alox - KI小鼠与野生型对照动物进行比较测试。在这些实验中，我们量化了炎症急性期和消退期炎症症状的严重程度。
我们发现，当以体重减轻作为主要读数参数时，在葡聚糖硫酸钠结肠炎模型中，Alox15基因敲入小鼠能有效免受炎症症状的发展。结肠组织氧化脂质组的定量分析表明，Alox15 - KI小鼠结肠中消退素D5的浓度升高，因此，这种介质可能有助于我们的基因操作所诱导的保护作用。然而，其他专门的促消退介质，如maresin - 2、神经保护素 - 1和脂氧素，可能对保护反应不起主要作用。在弗氏完全佐剂诱导的爪肿胀炎症模型中未观察到保护作用。
综上所述，我们的数据表明小鼠Alox15反应特异性的人源化（Leu353Phe突变）在两种小鼠炎症模型中表现出不同的作用。
