Researchers have discovered a rapid, efficient and simultaneous way of analysing diverse classes of metabolites in faeces. In a new study, they demonstrated that the technology can identify whether people have various diseases based on a single stool sample.
Many diseases such as those affecting the liver, kidney and gut can be difficult to diagnose because internal organs usually require invasive examinations, such as biopsies, to identify the disease.
But diagnosis may become much easier in the future, now that researchers have enabled the rapid analysis of diverse classes of metabolites in a single stool sample.
Since diseases in internal organs often alter the composition of metabolites in the gut, researchers can thus identify whether a person might have a disease and which one.
“This means that we can now envision being able to rapidly diagnose many diseases by using non-invasive faeces samples instead of invasive biopsies,” explains a researcher behind the study, Andressa de Zawadzki, Postdoctoral Fellow, Steno Diabetes Center Copenhagen.
The research, published in Metabolites, was carried out by Andressa de Zawadzki under the leadership of Cristina Legido-Quigley, Research Leader, Systems Medicine Research, Steno Diabetes Center Copenhagen.
Several reasons for interest in gut metabolites
For many years, researchers have been interested in studying the composition of metabolites in the gut.
Because each organ excretes metabolites to the gut, the metabolites indicate the state of health of the organs. Several studies have already indicated that the presence of given metabolites in faeces indicates that an individual probably has a specific organ-related disease. The metabolites can thus be used as biomarkers for disease.
Gut bacteria also excrete many metabolites, and the composition of gut bacteria is crucial for health. Screening these metabolites provides insight into whether a person has a healthy or unhealthy composition of gut bacteria.
Interest in screening the gut metabolites has been considerable, but this process has been cumbersome and protracted so far. Andressa de Zawadzki explains that different techniques have been required for each type of gut metabolites. For example, two very different techniques have been needed to analyse amino acids and bile acids.
“We have different methods of analysis that are very specific to the various classes of metabolites. Some can analyse bile acids and others amino acids, and this makes the whole process of using metabolites to pinpoint disease time-consuming and expensive,” she says.
Analysing all metabolites simultaneously
The researchers have developed a method to analyse several gut metabolites simultaneously. They purify faeces by adding chemicals that enable liquid chromatography and mass spectrometry to analyse the sample for amino acids and bile acids simultaneously.
The liquid chromatography categorises the metabolites according to their polarity, and mass spectrometry categorises them according to their molecular weight and electrical charge.
“We have developed a new way of preparing the stool samples that enables us to analyse diverse classes of metabolites with one liquid chromatographic injection and one mass spectrometry analysis. This means that we can analyse everything simultaneously and save time and resources because we only have to perform the analysis once instead of several times,” explains Andressa de Zawadzki.
Identifying people with alcohol-related liver disease
The researchers also validated that they can use their analyses to indicates people’s health status and will develop this further in future studies. They studied the metabolites in stool samples from 475 people with alcohol-related liver disease and healthy people as controls.
The researchers prepared the stool samples with their new method and analysed them for 28 metabolites, clearly finding that the profile of metabolites differed between the healthy controls and people with alcohol-related liver disease.
“Our next step will be to determine whether we can differentiate the stages of alcohol-related liver disease, including inflammation and fibrosis. This study merely aimed to develop a method to identify the differences,” says Andressa de Zawadzki.
Extending the research
Andressa de Zawadzki says that the study is just the first step on the road to even more discoveries.
The researchers will now use this method to identify various diseases by examining metabolites in faeces.
In addition, the researchers are already combining analysis of stool metabolites with that of bacterial genes and the composition of gut bacteria.
“The new method has a very distinct advantage that we do not merely determine the relative ratios of the stool metabolites but also the specific concentrations. So we can hopefully determine the healthy range for the concentrations of specific metabolites, and concentrations exceeding this range then indicate possible disease,” concludes Andressa de Zawadzki.