Reductions in circulating levels of IL-16, IL-7 and VEGF-A in myalgic encephalomyelitis/chronic fatigue syndrome.
Landi, Abdolamir, Broadhurst, David, Vernon, Suzanne D et al. · Cytokine · 2016 · DOI
Quick Summary
Researchers measured 34 different immune system proteins in blood samples from 100 ME/CFS patients and 79 healthy controls. They found that three specific immune proteins—IL-16, IL-7, and VEGF-A—were significantly lower in ME/CFS patients. This pattern was different from what is seen in other chronic diseases with similar fatigue symptoms, suggesting it may be unique to ME/CFS.
Why It Matters
This study identifies a potential blood-based signature specific to ME/CFS that distinguishes it from other diseases with chronic fatigue. Finding biomarkers could eventually help with diagnosis and may provide insights into underlying immune dysfunction mechanisms in ME/CFS. The correlation of three biomarkers as a cluster suggests a coherent biological pathway that warrants further investigation.
Observed Findings
Circulating IL-16 levels were significantly reduced in ME/CFS patients compared to controls
Circulating IL-7 levels were significantly reduced in ME/CFS patients compared to controls
Circulating VEGF-A levels were significantly reduced in ME/CFS patients compared to controls
These three biomarkers showed significant positive correlation in multivariate cluster analysis
Reduced fractalkine (CX3CL1) and MIG (CXCL9) were also observed, while eotaxin-2 (CCL24) was increased
Inferred Conclusions
The clustered reduction of IL-7, IL-16, and VEGF-A may have physiological relevance specific to ME/CFS pathology
This three-protein biomarker profile appears to be ME/CFS-specific, as it does not occur in chronic infectious or autoimmune liver diseases despite similar fatigue symptoms
IL-16 reduction in ME/CFS is a novel finding not previously reported in the literature
The consistency of IL-7 and VEGF-A findings with previous ME/CFS cohorts strengthens confidence in these biomarkers
Remaining Questions
What are the functional consequences of reduced IL-16, IL-7, and VEGF-A in ME/CFS pathophysiology?
What This Study Does Not Prove
This study does not prove that low IL-16, IL-7, and VEGF-A cause ME/CFS—it only shows an association. It does not explain why these proteins are reduced or what biological consequences result from their reduction. Being a single cross-sectional study, results require replication in other ME/CFS cohorts before conclusions about disease-specificity are confirmed.