Uncovering the role of bile acids in human health

Bile acids are synthesized in the liver and play multiple roles in digestion and metabolism. However, when their processes are disrupted, disease can occur. Scientists seek advanced technologies to better understand these metabolites and their impact on health.

In this Innovation Spotlight, Thomas Horvath, an analytical chemist at Baylor College of Medicine, and Paul Baker, a lipidomics and metabolomics scientist at SCIEX, join cell biologist Amy Engevik to discuss the complexities of bile acid research and its implications for humans. Potential Health Impacts Maxim Seferovic, a molecular biologist at the Medical University of South Carolina, Baylor College of Medicine, and Donald Chace, laboratory director at Capitainer Inc. Here, these experts share their insights into biochemical complexities, analytical challenges, and diagnostic potential. The role of bile acids in human disease.

What are bile acids?

Thomas Horvath: Bile acids are cholesterol-derived compounds that are essential for digesting lipids and regulating metabolic pathways. They travel through a biochemical circuit called the enterohepatic cycle, moving from the liver to the intestine, where they are transformed through the interaction of the host and microorganisms to produce a complex series of metabolites. This complex process allows bile acids to function as metabolic regulators, beyond digestive effects. However, disruption of this circuit can lead to gastrointestinal disease, making bile acids a key focus of medical research.

Why is bile acid analysis important for understanding human health?

Thomas Horvath: Disturbed bile acid profiles are associated with gastrointestinal diseases such as inflammatory bowel disease (IBD), necrotizing enterocolitis, primary sclerosing cholangitis, and biliary atresia.¹ My research, together with Amy Engevik’s research on microvillous inclusion disease (MVID) and Maxim Seferovic’s research on intrahepatic cholestasis of pregnancy (IHCP), attempts to understand these diseases at the molecular level. Advanced tools such as SCIEX’s ZenoTOF 7600 system allow us to analyze bile acids with unprecedented specificity, providing insights into their role in human health and disease.

Why is bile acid research so difficult? What are the technical challenges?

Thomas Horvath: The study of bile acids is challenging for three main reasons. First, their chemical diversity is extremely broad, with thousands of bile acid structures known and new types being discovered frequently.² Second, analytical techniques face limitations, including high levels of chemical noise in mass spectrometry (MS) methods, particularly instruments that rely on precursor ion to precursor ion transitions. Third, bile acid molecules have similar physicochemical properties, making it difficult to accurately separate and identify isomers.

Is there a way to do better bile acid analysis? If so, what is it and how does it help researchers gain the insights they need?

Paul Baker: Traditionally, bile acids have been analyzed using triple quadrupole mass spectrometry (TQMS). TQMS instruments, while sensitive, lack the specificity required to accurately differentiate bile acids, particularly due to the challenges of bile acid fragments, isomeric compounds, and chemical noise. Recently, we developed an improved high-resolution method using the ZenoTOF 7600 system that provides greater specificity by capturing unique fragment ions and bypassing typical noise challenges in traditional MS. This electron-based fragmentation, called electron-activated dissociation (EAD), provides unprecedented specificity and accuracy. Therefore, we are developing an assay that does not rely solely on chromatography to achieve specificity. A sensitive and specific high-throughput assay that can analyze bile acids in less than 10 minutes could be a game-changer.

What are you most excited about about the latest developments in bile acid analysis?

Maxim Seferovich: Technological advances in MS have opened the door to understanding bile acids beyond their digestive roles. They are now recognized as key metabolites affecting intestinal and systemic health. By identifying novel bile acid metabolites, we are piecing together how these compounds interact with various cellular systems, including the gut microbiome, to influence human health and disease. This development will help decode the communication pathways between the microbiota and the host and further elucidate the role of bile acids in biological systems.

Amy Engwick: I am excited about the increasing precision of bile acid analysis, which allows us to map the interactions between bile acids, gut bacteria, and the host. Through MS, we can distinguish bile acid types (primary bile acids, secondary bile acids, and tertiary bile acids) to gain insights into gastrointestinal diseases. Understanding these differences could shed light on how bile acid imbalance affects inflammation and immune responses in diseases such as IBD.³ Technologies such as EAD MS enhance our ability to explore these complex pathways and their impact on health.

What can researchers learn about gastrointestinal diseases such as IBD, MVID, and IHCP by analyzing bile acids using methods such as MS?

Maxim Seferovich: IHCP is a disorder with elevated bile acid levels that affects both mothers and children, but its mechanisms remain largely unknown. The ability to use MS to distinguish individual bile acid types provides new understanding of IHCP and other diseases. With these high-resolution data, we can go beyond total bile acid measurements to assess the impact of specific bile acid variants, which may reveal new therapeutic targets and ways to improve fetal health.⁴

Amy Engwick: In diseases such as MVID and IBD, bile acids play a crucial role. MVID is a rare disease that causes severe diarrhea and is associated with mutations in bile acid transport.⁵ IBD is a chronic inflammatory disease that may involve disruption of bile acid balance. By analyzing these diseases, we can track how bile acids contribute to inflammation and explore targeted therapies that may alleviate symptoms. Using MS, we can analyze individual bile acids to determine how their imbalance contributes to inflammation and other symptoms of these diseases. This analysis may lead to bile acid-based therapies to improve fat and bile acid absorption, which could benefit patients with nutrient malabsorption problems.

What are your career prospects in mass spectrometry and bile acid analysis?

Maxim Seferovich: My lab focuses on studying how changes in maternal diet, medications, and microbiome during pregnancy affect fetal development, with bile acids being a key factor. Our analysis of specific bile acid variants may link these metabolites to developmental outcomes. This study may shed light on how microbiome-derived bile acids influence fetal growth and long-term health, bridging the gap between maternal health and offspring.

Amy Engwick: We are integrating bile acid analysis into animal models of diseases such as MVID and IBD. Using MS, we can track how microbial communities interact with bile acids to influence host health. This may reveal novel bile acid derivatives with systemic effects beyond the gut, including neurological consequences.

What historical context can you use to predict the future of bile acid analysis?

Donald Chase: The foundation for modern bile acid analysis was laid by Robert Guthrie’s dried blood spot method for newborn screening in the 1960s.⁶ The technology was further developed in the 1990s for use in the diagnosis of metabolic disorders. Advanced MS capabilities can lead the expansion of bile acid research as we expand into methods such as drying fecal spots.⁷