Figure 4.

Expression of the pentose phosphate pathway (PPP) is upregulated at the protein level in Myalgic Encephalomyelitis (ME/CFS) lymphoblasts. Error bars represent the standard error of the mean. Mass spectrometry proteomics experiment: ME/CFS n = 34, control n = 31. Each cell line was sampled once, or twice for a subset of healthy controls arbitrarily selected to act an internal control between experiments. (A) A total of 7 PPP enzymes were detected within the whole-cell proteomes of lymphoblasts from ME/CFS and control lymphoblasts. Fold change refers to the mean abundance of a given protein in the CFS group divided by the mean abundance in the control group. There was no significant difference in the proportion of upregulated PPP enzymes (binomial test with H_o set to 0.5), but the magnitude of upregulation was significantly elevated in ME/CFS lymphoblasts (single-sample t test with H_o m ≤1 and H₁ m>1, p = 0.034). (B) A total of 7 RNA transcripts encoding PPP enzymes were detected by RNA sequencing within the whole-cell transcriptomes of ME/CFS and control lymphoblasts. Mean fold change was calculated for the ME/CFS group versus the control average for each transcript. The proportions of reduced or elevated transcripts were not significantly different (binomial test with H_o set to 0.5) nor was the average magnitude of expression (single-sample t test with H_o m = 1). (C) The expression level of G6PD is significantly elevated (t test, p = 5.5 × 10⁻⁴) in whole-cell mass spectrometry proteomics experiments (independent t test). Relative abundance was obtained from Intensity-Based Absolute Quantitation values normalised to the control average within the respective individual experiments.