Whole blood gene expression in adolescent chronic fatigue syndrome: an exploratory cross-sectional study suggesting altered B cell differentiation and survival

Abstract

BackgroundChronic fatigue syndrome (CFS) is a prevalent and disabling condition affecting adolescents. The pathophysiology is poorly understood, but immune alterations might be an important component. This study compared whole blood gene expression in adolescent CFS patients and healthy controls, and explored associations between gene expression and neuroendocrine markers, immune markers and clinical markers within the CFS group.MethodsCFS patients (12–18 years old) were recruited nation-wide to a single referral center as part of the NorCAPITAL project. A broad case definition of CFS was applied, requiring 3 months of unexplained, disabling chronic/relapsing fatigue of new onset, whereas no accompanying symptoms were necessary. Healthy controls having comparable distribution of gender and age were recruited from local schools. Whole blood samples were subjected to RNA sequencing. Immune markers were blood leukocyte counts, plasma cytokines, serum C-reactive protein and immunoglobulins. Neuroendocrine markers encompassed plasma and urine levels of catecholamines and cortisol, as well as heart rate variability indices. Clinical markers consisted of questionnaire scores for symptoms of post-exertional malaise, inflammation, fatigue, depression and trait anxiety, as well as activity recordings.ResultsA total of 29 CFS patients and 18 healthy controls were included. We identified 176 genes as differentially expressed in patients compared to controls, adjusting for age and gender factors. Gene set enrichment analyses suggested impairment of B cell differentiation and survival, as well as enhancement of innate antiviral responses and inflammation in the CFS group. A pattern of co-expression could be identified, and this pattern, as well as single gene transcripts, was significantly associated with indices of autonomic nervous activity, plasma cortisol, and blood monocyte and eosinophil counts. Also, an association with symptoms of post-exertional malaise was demonstrated.ConclusionAdolescent CFS is characterized by differential gene expression pattern in whole blood suggestive of impaired B cell differentiation and survival, and enhanced innate antiviral responses and inflammation. This expression pattern is associated with neuroendocrine markers of altered HPA axis and autonomic nervous activity, and with symptoms of post-exertional malaise. Trial registration Clinical Trials NCT01040429Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-017-1201-0) contains supplementary material, which is available to authorized users.

Associations between clinical symptoms, plasma norepinephrine and deregulated immune gene networks in subgroups of adolescent with Chronic Fatigue Syndrome

“…Plasma levels of Transforming Growth Factor b (TGF-b) including three isoforms of TGF-β (TGF-β1, TGF-β2 and TGF-β3) was analyzed using Bio-Plex Human TGF-β 3-plex (Bio-Rad Laboratories Inc., Hercules, CA, USA) and performed by the Bio-Plex200 system. Neuroendocrine/autonomic markers (plasma and urine levels of norepinephrine and epinephrine) were collected as previously described and measured by the use of high performance liquid chromatography (HPLC) with a reversed-phase column and glassy carbon electrochemical detector (Antec, Leyden Deacade II SCC, Zoeterwoude, The Netherlands) 6,21 . The low frequency:high frequency (LF/HR) ratio of supine heart rate variability is an index of sympathetic versus parasympathetic heart rate control; it was calculated from 4 minutes ECG recordings of horizontal-laying participants connected to the Task Force Monitor (Model 3040i, CN Systems Medizintechnik, Graz, Austria) as described elsewhere 22 .…”

“…Random sampling of 29 CFS patients and 18 healthy controls at time of inclusion (baseline) with similar demographical and clinical parameters compared to the NorCapital cohort were used for whole blood RNA extraction 6 . These two groups were homogenous for age and gender ( Table 1).…”

“…After removing globin and ribosomal RNAs, mRNA sequencing was performed on the Illumina HiSeq 2500 according to the protocol of TruSeq Stranded mRNA single-end sequencing. Normalization of gene expression data from this whole blood was performed using RUVSeq and differential expression analysis was done using DESeq2 as described previously 6 .…”

“…The aetiology of CFS is unknown; however, several studies have linked its pathophysiology to perturbation in the immune system including altered function of B cells, Tregs, neutrophils and NK cells 3,4 and altered levels of certain cytokines associated with disease duration 5 . Recently, we identified subtle downregulation of genes encoding proteins that function in adaptive immune responses and upregulation of genes belonging to innate responses in whole blood mRNA of young CFS patients compared with healthy controls 6 . Additionally, CFS is characterized by neuroendocrine alterations including enhanced sympathetic nervous activity, increased plasma levels of catecholamines and attenuation of the hypothalamus-pituitary-adrenal axis (HPA-axis) [7][8][9] Increasing evidences in systems biology have suggested that studying higher degree of molecular interactions might shed light on the underlying mechanisms of complex diseases 10,11 .…”

Non-invasive characterization of human bone marrow by cell free messenger-RNA reveals response to growth factor stimulation and hematopoietic reconstitution after transplantation

“…(Fig 1A). To gain insights into the origin of these transcripts, similar deconvolution analysis was performed in whole blood samples from 19 healthy individuals from previously reported RNA-Seq data 20 . As expected, the whole blood transcriptome is largely composed of lymphocyte (69.1%) and granulocyte (21.8%) transcripts, with an additional 7.5% of transcripts of erythrocyte origin and minor contributions from other cell types and tissues ( Fig 1A).…”