Addressing the Microbiome, Innate Immunity
W. Ian Lipkin, MD, of Columbia University, New York, NY, was one of two speakers who discussed the role of disruptions in the microbiome and innate immunity in ME/CFS. He presented data suggesting that “dysregulation of the gut microbiome in ME/CFS may interfere with butyrate production, resulting in inflammation and porosity to bacteria and bacterial products that trigger innate immunity.”
Dr. Lipkin highlighted a “really intriguing” paper in which exogenous administration of interleukin 37 (IL-37), a naturally occurring inhibitor of inflammation, reversed the decrease in exercise performance observed during inflammation-induced fatigue and increased exercise performance, both in mice.
“Although we do not fully understand the pathophysiology of ME/CFS, it is not premature to consider randomized clinical trials of pro- and pre-biotics that address dysbiosis as well as drugs that modify innate immune responses such as poly (I:C) and IL-37,” Dr. Lipkin said.
Alleviating Endoplasmic Reticulum (ER) Stress: A Strategy to Increase Energy?
Paul M. Hwang, MD, PhD, from the Cardiovascular Branch of the National Heart, Lung, and Blood Institute, Bethesda, Maryland, described work that he and his colleagues recently published around a case of a 38-year-old woman with Li-Fraumeni syndrome, a genetic early-onset cancer, who also had extensive fatigue, exercise intolerance, and post-exertional malaise that began after she contracted mononucleosis as a teenager.
Testing revealed that her cells had increased expression of Wiskott-Aldrich Syndrome Protein Family Member 3 (WASF3), a “top candidate” gene found to be associated with ME/CFS in a bioinformatics study published more than a decade ago. Moreover, immunoblotting of deidentified skeletal muscle biopsy samples obtained from patients with postinfectious ME/CFS also revealed significantly increased WASF3 levels.
Hwang and colleagues showed in mice that ER stress–induced WASF3 protein localizes to mitochondria and disrupts respiratory supercomplex assembly, leading to decreased oxygen consumption and exercise endurance.
However, use of the investigational protein phosphatase 1 inhibitor salubrinal in the female patient’s cells inhibited the ER stress, which in turn decreased WASF3 expression and improved mitochondrial supercomplex formation and respiration, “suggesting a treatment strategy in ME/CFS,” Dr. Hwang said.
Neurovascular Dysregulation During Exercise: A Role for Pyridostigmine?
David M. Systrom, MD, a pulmonary and critical care medicine specialist at the Brigham and Women’s Hospital, Boston, Massachusetts, gave an update of his work investigating neurovascular dysregulation during exercise in both ME/CFS and long COVID using invasive cardiopulmonary testing.
In a 2021 publication, Dr. Systrom and his colleagues identified the mechanism of “preload failure,” or lower filling pressures of blood in the heart chambers because of insufficient vein constriction and reduced return of blood to the right side of the heart in people with ME/CFS, compared with healthy controls.
Subsequently, in a randomized trial of 45 patients with ME/CFS, Systrom and his colleagues published in November 2022, use of the cholinesterase inhibitor pyridostigmine, currently approved for treating myasthenia gravis and related conditions, improved peak Vo2 by increasing cardiac output and filling pressures.
Now, Dr. Systrom’s team is conducting a randomized trial comparing 60 mg pyridostigmine with or without low-dose naltrexone (LDN) vs placebo in 160 patients with ME/CFS for 3 months. Metabolomic, transcriptomic, proteomic, and other assessments will be conducted on urine and blood samples. Participants will also wear devices that measure steps, sleep, heart rate, and other metrics.
Komaroff cautioned that pyridostigmine, too, has potential adverse effects. “I’m not sure pyridostigmine is ready for prime time ... It’s a drug developed for a very different purpose ... Now will it hold up in a larger trial, and will there be any side effects that turn up in larger studies? It’s not unreasonable to study.”