Deep phenotyping of Post-infectious Myalgic Encephalomyelitis/Chronic Fatigue Syndrome [RNA-Seq]

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a disabling disorder that may occur following an infection, yet the clinical phenotype is poorly defined, the pathophysiology is unknown, and no disease-modifying treatments are available. We used rigorous criteria to recruit a cohort of post-infectious ME/CFS (PI-ME/CFS) volunteers (n=17) with matched healthy controls (n=21) to conduct deep clinical and biological phenotyping using an extensive battery of tests. Among the many physical and cognitive complaints, one defining feature of PI-ME/CFS was an alteration of effort preference, rather than physical or central fatigue, due to dysfunction of integrative brain regions potentially associated with central catechol pathway dysregulation, with consequences on autonomic functioning and physical deconditioning. Immune profiling suggested chronic antigenic stimulation with increase in naïve and decrease in switched memory B-cells. Alterations in gene expression profiles of peripheral blood mononuclear cells and metabolic pathways were consistent with cellular phenotypic studies and demonstrated differences according to sex. Together these clinical abnormalities and biomarker differences provide unique insight into the underlying pathophysiology of PI-ME/CFS, which may guide future intervention. Muscle RNA Sequencing: RNA was extracted from muscle samples using the TRIzol protocol 63. The integrity of the RNA was verified using a standard quality metric denominated RNA integrity number (RIN) value using the Agilent 4200 TapeStation system and the concentration was measured using the DeNovix DS-11 spectrophotometer. Five hundred nanograms of RNA were used to prepare the RNA sequencing libraries using the NEBNext Ultra II Directional RNA Library Prep Kit and sequenced using the Illumina NovaSeq 6000 sequencer. Reads were demultiplexed using bcl2fastq v. 2.20.0. Participants: A total of 27 post-infectious Myalgic encephalomyelitis/chronic fatigue syndrome (PI-ME/CFS) volunteers underwent research evaluation at the National Institutes of Health (NIH) Clinical Center. Two participants withdrew after providing informed consent and completing a history and physical exam without undergoing any research investigations. Of the remaining 25 PI-ME/CFS participants, four were found to have previously undiagnosed medical conditions that were related to ME/CFS symptoms. This included one case each of desmoplastic small round cell tumor, atypical inflammatory myositis, primary biliary cholangitis, and parkinsonism. Of the remaining 21 PI-ME/CFS participants, four participants were determined not to have a demonstrable infectious association to their ME/CFS symptoms during the case adjudication process (Table S2C). Details about the case adjudication process can be reviewed below in Supplement, Methods. A total of 17 adjudicated PI-ME/CFS volunteers completed the initial deep phenotyping measurements; eight of these volunteers also completed the exercise stress measurements. A total of 25 healthy volunteers (HVs) were recruited to serve as comparator volunteers. Of these, one volunteer withdrew prior to completing deep phenotyping measurements. Three volunteers were excluded after evaluation related to asymptomatic medical conditions were identified. One had leukodystrophy, another had pleocytosis in the cerebrospinal fluid, and the third had early onset dementia. A total of 21 healthy volunteer comparators completed the initial deep phenotyping measurements; nine of these comparators also completed the exercise stress measurements. contributor: The CHI Consortium