Investigation of cardiolipin oxidation products as a new endpoint for oxidative stress in C. elegans by means of online two-dimensional liquid chromatography and high-resolution mass spectrometry

Abstract

The investigation of neurodegenerative and age-related diseases is a highly relevant topic in current research. Especially oxidative stress is thought to be the common underlying mechanism in diseases such as Parkinson’s or Alzheimer’s disease. The nematode Caenorhabditis elegans (C. elegans) is a prominent model organism, which is often used for such investigations and has gained extensive recognition in research regarding the linkage of reactive oxygen species (ROS) and neurodegeneration. Not only studies regarding genomics and proteomics have been increasingly conducted, also the number of studies based on the lipidome is rising. The phospholipid class of cardiolipin (CL) is a unique lipid class, which is exclusively located in mitochondria and is therefore of great relevance regarding oxidative stress and associated diseases. CL oxidation products have become a prominent marker for oxidative stress in various organisms. However, the CL distribution in the nematode C. elegans is still scarcely known on the molecular level and oxidation products have not yet been identified. In this work, we demonstrate the importance of CL distribution and the applicability of CL oxidation products as a sensitive marker for oxidative stress in C. elegans. For this reason, the CL distribution was determined by means of online two-dimensional liquid chromatography hyphenated with high-resolution mass spectrometry (2D-LC/HRMS). Subsequently, worms were treated with tert-butyl hydroperoxide (tBOOH) in order to provoke oxidative stress and induce the artificial formation of oxidized CL. We were able to detect increasing amounts of CL oxidation products of highly unsaturated CL species in a concentration-dependent manner. This finding emphasizes the great potential of CL oxidation products as a sensitive marker substance of oxidative stress in C. elegans, which is not only directly linked to mitochondria function but also favourable to other oxidative stress markers in terms of the needed sample material, relative substance stability and specificity of the oxidation site.