Previously undetectable biomarkers in gut microbiome may predict 'invisible' chronic fatigue syndrome, long COVID

Millions suffering from myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a debilitating condition often overlooked due to the lack of diagnostic tools, may be closer to personalized care, according to new research that shows how the disease disrupts interactions between the microbiome, immune system, and metabolism, according to Medical Xpress.

The findings—potentially relevant to long COVID due to its similarity with ME/CFS—come from data on 249 individuals analyzed using a new artificial intelligence (AI) platform that identifies disease biomarkers from stool, blood, and other routine lab tests.

"Our study achieved 90% accuracy in distinguishing individuals with chronic fatigue syndrome, which is significant because doctors currently lack reliable biomarkers for diagnosis," said study author Dr. Derya Unutmaz, Professor of immunology at The Jackson Laboratory (JAX). "Some physicians doubt it as a real disease due to the absence of clear laboratory markers, sometimes attributing it to psychological factors."

The research was led by Dr. Julia Oh, formerly at JAX and now a microbiologist and professor at Duke University, in collaboration with ME/CFS clinicians Lucinda Bateman and Suzanne Vernon of the Bateman Horne Center, and Unutmaz, who directs the JAX ME/CFS Collaborative Research Center.

Mapping the invisible Chronic fatigue syndrome is characterized by severe symptoms that significantly impair physical and mental activities, including persistent fatigue, sleep abnormalities, dizziness, and chronic pain.

Experts often compare ME/CFS to long COVID, as both conditions frequently follow viral infections, such as Epstein-Barr virus. In the United States, ME/CFS affects between 836,000 and 3.3 million individuals— many undiagnosed—and costs the economy $18 to $51 billion annually due to health care expenditures and lost productivity, according to the Centers for Disease Control and Prevention. Prior studies have noted immune disruptions in ME/CFS, Unutmaz said. This new research builds upon those findings by investigating how the gut microbiome, its metabolites, and immune responses interact. The team linked these connections to 12 classes of patient-reported symptoms, which were aggregated from hundreds of datapoints generated by patient health and lifestyle surveys. These include sleep disturbances, headaches, fatigue, dizziness, and other symptoms the researchers mapped in their entirety from microbiome changes to metabolites, immune responses, and clinical symptoms. "We integrated clinical symptoms with cutting-edge omics technologies to identify new biomarkers of ME/CFS," Oh said. "Linking symptoms at this level is crucial, because ME/CFS is highly variable. Patients experience a wide range of symptoms that differ in severity and duration, and current methods can't fully capture that complexity."

To conduct the study, the researchers analyzed comprehensive data collected from the Bateman Horne Center, a leading ME/CFS, long COVID, and fibromyalgia research center in Salt Lake City, Utah.

Dr. Ruoyun Xiong, also a lead author on the study, developed a deep neural network model called BioMapAI. The tool integrates gut metagenomics, plasma metabolomics, immune cell profiles, blood test data, and clinical symptoms from 153 patients and 96 healthy individuals over four years. Immune cell analysis proved most accurate in predicting symptom severity, while microbiome data best predicted gastrointestinal, emotional, and sleep disturbances. The model connected thousands of patient data points, reconstructing symptoms such as pain and gastrointestinal issues, among several others. It also revealed that patients who were ill for less than four years had fewer disrupted networks than those who were ill for more than ten years.

"Our data indicate these biological disruptions become more entrenched over time," Unutmaz said. "That doesn't mean longer-duration ME/CFS can't be reversed, but it may be more challenging." The study included 96 age- and gender-matched healthy controls, showing balanced microbiome-metabolite-immune interactions, in contrast to significant disruptions in ME/CFS patients linked to fatigue, pain, emotional regulation issues, and sleep disorders.

ME/CFS patients also had lower levels of butyrate, a beneficial fatty acid produced in the gut, along with other nutrients essential for metabolism, inflammation control, and energy. Patients with elevated levels of tryptophan, benzoate, and other markers indicated a microbial imbalance. Heightened inflammatory responses, particularly involving MAIT cells sensitive to gut microbial health, were also observed. "MAIT cells bridge gut health to broader immune functions, and their disruption alongside butyrate and tryptophan pathways, normally anti-inflammatory, suggests a profound imbalance," said Unutmaz.

An actionable dataset

Even though the findings require further validation, they significantly advance scientists' understanding of ME/CFS and provide clearer hypotheses for future research, the authors said.

Since animal models can't fully reflect the complex neurological, physiological, immune, and other system disruptions seen in ME/CFS, Oh said it will be crucial to study humans directly to identify modifiable factors and develop targeted treatments.