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Illness progression in chronic fatigue syndrome: a shifting immune baseline
†Contributed equally
- Lindsey Russell†,
- Gordon Broderick†Email authorView ORCID ID profile,
- Renee Taylor,
- Henrique Fernandes,
- Jeanna Harvey,
- Zachary Barnes,
- AnneLiese Smylie,
- Fanny Collado,
- Elizabeth G. Balbin,
- Ben Z. Katz,
- Nancy G. Klimas and
- Mary Ann Fletcher
BMC Immunology201617:3
DOI: 10.1186/s12865-016-0142-3
© Russell et al. 2016
Received: 7 August 2015
Accepted: 29 February 2016
Published: 10 March 2016
Abstract
Background
Validation of biomarkers for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) across data sets has proven disappointing. As immune signature may be affected by many factors, our objective was to explore the shift in discriminatory cytokines across ME/CFS subjects separated by duration of illness.
Methods
Cytokine expression collected at rest across multiple studies for female ME/CFS subjects (i) 18 years or younger, ill for 2 years or less (n = 18), (ii) 18–50 years of age, ill for 7 years (n = 22), and (iii) age 50 years or older (n = 28), ill for 11 years on average. Control subjects were matched for age and body mass index (BMI). Data describing the levels of 16 cytokines using a chemiluminescent assay was used to support the identification of separate linear classification models for each subgroup. In order to isolate the effects of duration of illness alone, cytokines that changed significantly with age in the healthy control subjects were excluded a priori.
Results
Optimal selection of cytokines in each group resulted in subsets of IL-1α, 6, 8, 15 and TNFα. Common to any 2 of 3 groups were IL-1α, 6 and 8. Setting these 3 markers as a triple screen and adjusting their contribution according to illness duration sub-groups produced ME/CFS classification accuracies of 75–88 %. The contribution of IL-1α, higher in recently ill adolescent ME/CFS subjects was progressively less important with duration. While high levels of IL-8 screened positive for ME/CFS in the recently afflicted, the opposite was true for subjects ill for more than 2 years. Similarly, while low levels of IL-6 suggested early ME/CFS, the reverse was true in subjects over 18 years of age ill for more than 2 years.
Conclusions
These preliminary results suggest that IL-1α, 6 and 8 adjusted for illness duration may serve as robust biomarkers, independent of age, in screening for ME/CFS.
http://bmcimmunol.biomedcentral.com/articles/10.1186/s12865-016-0142-3