Scientists at the Center for Infection and Immunity at Columbia University's Mailman School of Public Health report that they have identified distinct immune changes in patients diagnosed with chronic fatigue syndrome, known medically as myalgic encephalomyelitis (ME/CFS) or systemic exertion intolerance disease. They say their findings could help improve diagnosis and identify treatment options for the disabling disorder, in which symptoms range from extreme fatigue and difficulty concentrating to headaches and muscle pain.
These immune signatures represent the first robust physical evidence that ME/CFS is a biological illness as opposed to a psychological disorder, and the first evidence that the disease has distinct stages. The team’s study (“Results Distinct plasma immune signatures in ME/CFS are present early in the course of illness”) appear online in Science Advances.
The researchers used immunoassay testing methods to determine the levels of 51 immune biomarkers in blood plasma samples collected through two multicenter studies that represented a total of 298 ME/CFS patients and 348 healthy controls. They found specific patterns in patients who had the disease three years or less that were not present in controls or in patients who had the disease for more than three years. Short duration patients had increased amounts of many different types of cytokines. The association was unusually strong with interferon gamma, which has been linked to the fatigue that follows many viral infections, including Epstein-Barr virus (the cause of infectious mononucleosis). Cytokine levels were not explained by symptom severity.
“We found a stronger correlation of cytokine alterations with illness duration than with measures of illness severity, suggesting that the immunopathology of ME/CFS is not static,” wrote the investigators.
“We now have evidence confirming what millions of people with this disease already know, that ME/CFS isn't psychological,” says lead author Mady Hornig, M.D., director of translational research at the center. “Our results should accelerate the process of establishing the diagnosis after individuals first fall ill as well as discovery of new treatment strategies focusing on these early blood markers.”
There are already human monoclonal antibodies on the market that can dampen levels of interleukin-17A, which is among those the study shows were elevated in early-stage patients. Before any drugs can be tested in a clinical trial, Dr. Hornig and colleagues hope to replicate the current, cross-sectional results in a longitudinal study that follows patients for a year to see how cytokine levels, including interleukin-17A, differ within individual patients over time, depending on how long they have had the disease.
The study also supports the idea that ME/CFS may reflect an infectious hit-and-run event. Patients often report getting sick, sometimes from something as common as infectious mononucleosis, and never fully recover. The new research suggests that these infections throw a wrench in the immune system's ability to quiet itself after the acute infection, to return to a homeostatic balance.
“It appears that ME/CFS patients are flush with cytokines until around the three-year mark, at which point the immune system shows evidence of exhaustion and cytokine levels drop,” notes Dr. Hornig. “Early diagnosis may provide unique opportunities for treatment that likely differ from those that would be appropriate in later phases of the illness.”