Unravelling the nature of postexertional malaise in myalgic encephalomyelitis/chronic fatigue syndrome: the role of elastase, complement C4a and interleukin-1β

Nijs J, Van Oosterwijck J, Meeus M, Lambrecht L, Metzger K, Fremont M, Paul L (Vrije Universiteit Brussel, Brussels; University College Antwerp, Antwerp; University Hospital Brussels, Brussels; Private Practice for Internal Medicine, Gent/Aalst; and RED Laboratories N.V., Zellik; Belgium, and University of Glasgow, Glasgow, UK). Unravelling the nature of postexertional malaise in myalgic encephalomyelitis/chronic fatigue syndrome: the role of elastase, complement C4a and interleukin-1 beta. J Intern Med 2010; 267: 418-435. Objectives. Too vigorous exercise or activity increase frequently triggers postexertional malaise in people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a primary characteristic evident in up to 95% of people with ME/CFS. The present study aimed at examining whether two different types of exercise results in changes in health status, circulating elastase activity, interleukin (IL)-1 beta and complement C4a levels. Design. Comparative experimental design. Setting. University. Subjects. Twenty-two women with ME/CFS and 22 healthy sedentary controls Interventions: participants were subjected to a submaximal exercise (day 8) and a self-paced, physiologically limited exercise (day 16). Each bout of exercise was preceded and followed by blood sampling, actigraphy and assessment of their health status. Results. Both submaximal exercise and self-paced, physiologically limited exercise resulted in postexertional malaise in people with ME/CFS. However, neither exercise bout altered elastase activity, IL-1 beta or complement C4a split product levels in people with ME/CFS or healthy sedentary control subjects (P > 0.05). Postexercise complement C4a level was identified as a clinically important biomarker for postexertional malaise in people with ME/CFS. Conclusions. Submaximal exercise as well as self-paced, physiologically limited exercise triggers postexertional malaise in people with ME/CFS, but neither types of exercise alter acute circulating levels of IL-1 beta, complement C4a split product or elastase activity. Further studying of immune alterations in relation to postexertional malaise in people with ME/CFS using multiple measurement points postexercise is required.