Mitochondrial complex activity in permeabilised cells of chronic fatigue syndrome patients using two cell types

Abstract

Abnormalities in mitochondrial function have previously been shown in chronic fatigue syndrome (CFS) patients, implying that mitochondrial dysfunction may contribute to the pathogenesis of disease. This study builds on previous work showing that mitochondrial respiratory parameters are impaired in whole cells from CFS patients by investigating the activity of individual mitochondrial respiratory chain complexes. Two different cell types were used in these studies in order to assess individual complex activity locally in the skeletal muscle (myotubes) (n = 6) and systemically (peripheral blood mononuclear cells (PBMCs)) (control n = 6; CFS n = 13). Complex I, II and IV activity and respiratory activitysupported by fatty acid oxidation and glutaminolysis were measured usingextracellular flux analysis. Cells were permeabilised and combinations of substrates and inhibitors were added throughout the assays to allow states of mitochondrial respiration to be calculated and the activity of specific aspects of respiratory activity to be measured. Results showed there to be no significant differences in individual mitochondrial complex activity or respiratory activity supported by fatty acid oxidation or glutaminolysis between healthy control and CFS cohorts in either skeletal muscle (p ≥ 0.190) or PBMCs (p ≥ 0.065). This is the first study to use extracellular flux analysisto investigate individual mitochondrial complex activity in permeabilised cells in the context of CFS. The lack of difference in complex activity in CFS PBMCs suggests that the previously observed mitochondrial dysfunction in whole PBMCs is due to causes upstream of the mitochondrial respiratory chain.

An Isolated Complex V Inefficiency and Dysregulated Mitochondrial Function in Immortalized Lymphocytes from ME/CFS Patients

“…Instead of impaired glycolytic capacity driving the shift in metabolism, our results suggest that the change may be driven by elevated usage of alternatives such as the β oxidation of fatty acids. Fatty acid utilization rates were previously reported to be unchanged in permeabilized ME/CFS lymphocytes [41]. However, the permeabilization process (with loss of cytoplasmic cellular context, e.g., metabolites) or the metabolic quiescence and greater death rates of ME/CFS lymphocytes may have obscured the result in this previous study.…”

“…Previous steady state measurements and metabolic flux measurements of mitochondrial respiratory function in ME/CFS lymphocytes have suggested that in ME/CFS cells there is either a generalized reduction [6][7][8] or little change [9,15] in mitochondrial activity and respiratory capacity. However, functionally normal OXPHOS Complex I to IV activity has also been reported in ME/CFS lymphocytes [11,41], while the expression of mitochondrial proteins is upregulated in patient saliva, platelets and lymphocytes [12,13,23]. Elevated nonmitochondrial ATP production has also been reported in ME/CFS lymphocytes [11].…”

An Isolated Complex V Inefficiency and Dysregulated Mitochondrial Function in Immortalized Lymphocytes from ME/CFS Patients

“…Instead of impaired glycolytic capacity driving the shift in metabolism, our results suggest that the change may be driven by elevated usage of alternatives such as the  oxidation of fatty acids. Fatty acid utilization rates were previously reported to be unchanged in permeabilized ME/CFS lymphocytes [47]. However, the permeabilization process (with loss of cytoplasmic cellular context eg metabolites) or the metabolic quiescence and greater death rates of ME/CFS lymphocytes may have obscured the result in this previous study.…”

“…Previous steady state measurements and metabolic flux measurements of mitochondrial respiratory function in ME/CFS lymphocytes have suggested that in ME/CFS cells there is either a generalized reduction [6][7][8] or little change [9,15] in mitochondrial activity and respiratory capacity. However, functionally normal OXPHOS Complex I to IV activity has also been reported in ME/CFS lymphocytes [11,47], while the expression of mitochondrial proteins is upregulated in patient saliva, platelets and lymphocytes [12,13,30].…”

Multi-omics Examination of Q Fever Fatigue Syndrome Identifies Similarities with Chronic Fatigue Syndrome

“…Dennis et al showed that the 4E-BP1 phosphorylation was inhibited when intracellular adenosine triphosphate (ATP) levels were lowered (48). Interestingly, chronic fatigue has previously been associated with a decrease in cell metabolism (15,18,49,50), and PBMCs of CFS patients showed a decrease in mitochondrial function compared to PBMCs of HC when stressed (51)(52)(53). Axis inhibition protein (AXIN1), negatively regulates the Wnt signalling pathway by downregulation of β-catenin (54), but has also been identi ed as a scaffold protein that activates TGF-β signalling (55).…”