Blood Lipids Can Be a Crucial Indicator of Diabetes and Cardiovascular Disease
Ring trial enables ceramide reference values to be determined for the first time and paves the way for new biomarker tests
Certain fat molecules in the blood are considered promising candidates for detecting diseases such as diabetes, obesity, and cardiovascular diseases at an early stage. Ceramides play an important role in this context, as they indicate disease-related adaptation processes in the body. As part of a ring trial in which researchers from Forschungszentrum Jülich and the University of Vienna and teams of scientists from Singapore and Espoo (Finland) played a key role, important progress has now been made in determining reference values for ceramides. These values are needed for the development of corresponding biomarker tests. The results of the first phase of the ring trial were published in the renowned journal Nature Communications.
Lipidomics is the study of how fat molecules, known as lipids, work in the body and what role they play in health and disease. The basic aim is to analyse the structures, functions, and interactions of these molecules in the body’s cells and to understand their significance for the organism as a whole. In order to detect pathological deviations from the norm, it is important to know the upper and lower concentration limits. To this end, a worldwide ring trial was initiated under the umbrella of the International Lipidomics Society (ILS). In the first phase, the initial aim was to develop standardized measurement methods that could be used in laboratories internationally.
Interview with Dr. Nils Hoffmann providing background on the study
Some of the fat molecules examined, also known as lipids, are used in the Coronary Event Risk Test (CERT1) to assess the risk of coronary heart disease, serious heart attacks, heart failure, and strokes. Dr. Nils Hoffmann, bioinformatician and data scientist at Forschungszentrum Jülich’s Institute of Bio- and Geosciences – Computational Metagenomics (IBG-5), is one of the three lead authors of the study and was heavily involved in planning the study and harmonizing the exchange of data as well as blinded data integration, analysis, and visualization right from the start. In this interview, he provides some background on the study and explains how the results will now find application.
What are ceramides exactly?
Ceramides are lipid molecules that are formed during fat metabolism and are involved in many processes in our cells. An unhealthy diet, lack of exercise, and genetic factors promote the development of type 2 diabetes and cardiovascular disease. These diseases affect ceramide levels, which makes ceramides potential biomarkers for the early detection of these diseases. In addition, the ceramide metabolism can be influenced by medication, but also by changing diet and exercise habits.
How does a ring trial work?
A ring trial involves several laboratories independently analysing the same samples using similar or different methods in order to compare their results. This helps to assess the reliability and consistency of measurements in different laboratories and to improve the standardization and quality control of scientific tests. Such studies are usually very labour-intensive and time-consuming. In the case of the ceramide ring trial, the results were summarized after seven years of joint work by 34 participating laboratories from 19 countries. To maintain a strict focus while reducing complexity, this ring trial focused on human plasma or serum and aimed to investigate the concentrations and variability of four different ceramide lipids that can be used to assess the risk of a heart attack and related cardiovascular diseases.
What are the most important findings?
Some valuable lessons can be learned from the results of our ring trial. First of all, standardization is the key to reducing variation in the test procedure and reaching a consensus on the concentrations of ceramides tested. The mass spectrometric methods that we used to determine the ceramide concentrations in this ring trial are characterized by their high sensitivity. This is both advantageous and disadvantageous, as it allows even very low concentrations of substances to be measured and determined. At the same time, the quality of the measurements is dependent on the manual preparation of the samples.
The establishment of standards and routines in the laboratories involved is therefore very important for the reproducibility and reliability of the measured concentrations. An important task of this experiment was thus to provide the participating laboratories with a standard operating procedure (SOP) that had been successfully tested multiple times in order to reduce the influence of these steps on the results. However, the participating laboratories were also able to use their own measurement procedures in addition to the SOP and submit them for data analysis. The analysis showed that only in a few cases did the results differ significantly between the predefined measurement procedure and the laboratories’ own measurement procedures. In such cases, after consultation with the laboratories involved, the cause of these deviations was usually found. The ring trial therefore also served as a litmus test for the internal quality assurance processes of the participating laboratories.
What happens to the results now?
Determining the mean absolute ceramide concentrations helps form the basis for future biological and medical studies relevant to ceramide-associated diseases. The four ceramides selected in this study only represent a small proportion of the ceramides produced by the human body. There are many other ceramide-associated lipid classes that can be used to predict or diagnose other diseases. Currently, the chosen ceramides are mainly used for the Coronary Event Risk Test (CERT1), which can be used to assess the risk of serious heart attacks, heart failure, and strokes. A further development of this test, CERT2, also uses the concentrations and ratios of phospholipids in addition to the ceramides, which makes the test more accurate for the same area of application as CERT1.
In clinical research, these tests are currently being tested in combination with other lipid concentrations and ratios, including in connection with the early detection of other diseases associated with ceramide metabolism. For example, the exact mechanisms between cardiovascular diseases and altered ceramide concentrations have yet to be fully established. One of my research priorities over the next few years will be to study the development and validation of mechanistic hypotheses together with chemists, biologists, and physicians using data-based methods from modern bioinformatics and machine learning.
What is the role of the different types of plasma samples that were investigated in the study?
Thanks to our collaboration with the US National Institute of Standards and Technology (NIST), we had access to reference samples for this study, which were produced under controlled conditions. These samples are produced from blood plasma samples from a representative cross-section of the (American) population. For example, the main standard we used for this study, NIST SRM 1950, attempts to reflect the average variability of blood plasma in the adult American population.
The other three standards we used in the study consist of a sample of healthy young adults, a sample of severely overweight adults, and a sample of people with type 1 diabetes. By determining the concentrations in these different groups, we were able to show which concentration ranges can be expected for the ceramides in each respective group. Once the values have been validated on larger, representative cross-sections of the population, the results can be used to define threshold ranges above which, for example, a doctor would initiate drug treatment for his patients, or up to which he would recommend more exercise or an adapted diet to prevent cardiovascular disease. By comparing mixed plasma samples, the study provides initial results on biological differences between healthy individuals, people with elevated cholesterol levels, and people with type 1 diabetes. To better understand the typical concentration ranges of ceramides and their influencing factors, further ring trial phases are needed to determine variability and representativeness as a function of genetic factors and other individual factors, such as diet.
Original publication
Federico Torta, Nils Hoffmann, Bo Burla, et al.
Concordant inter-laboratory derived concentrations of ceramides in human plasma reference materials via authentic standards
Nature Communications (2024), DOI: 10.1038/s41467-024-52087-x
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