"Using flow cytometry, we compared mitochondrial bioenergetic parameters in CD19 B cells as well as CD4 and CD8 T cell lymphocyte populations. Sample gating strategy for identifying these lymphocyte populations is shown in Supplementary Figure S1A. Although we did not identify any differences between healthy controls and ME/CFS or LC donors in mitochondrial mass or membrane potential (Supplementary Figure S2), decreases in mitochondrial ATP levels were observed across ME/CFS (1.6x decrease on average; HC v. ME/CFS two-sided t-test CD4 T cells p = 0.0458, CD8 T cells p = 0.0974, CD19 B cells p = 0.356) and LC donors (2.8x decrease on average; HC v. LC two-sided t-test CD4 T cells p = 0.0076, CD8 T cells p = 0.0182, CD19 B cells p = 0.0842), compared to healthy controls (Supplementary Figure S2). Our findings are consistent with a published study showing oxidative phosphorylation defects among PBMCs in CFS patients, compared to healthy controls69"
Unstimulated PBMCs are quiescent and when taken out of the body are also dying (every researcher around the world that I have spoken to who has measured this in time course experiments also finds that they die faster in ME/CFS). Naturally you will see generalised decreases in functional indicators and generalised increases in damaging or dysfunctional indicators in ex vivo disease cells that are falling apart at the seams. ROS could easily be a cause of this death/dysfunction but it could also be an consequence. This needs to be tested directly in a future study.
"Based on our results in Figure 3A, which also detected changes in acylcarnitine metabolism in ME/CFS donors, we compared lipid droplet levels using HCS LipidTox Green Neutral Lipid staining, which stains for neutral intracellular lipid droplets. As shown in Supplementary Figure 4G, we found lower lipid droplet levels in both LC and ME/CFS donors across all measured lymphocyte populations (ME/CFS: CD19 p = 5.19*10-4 , CD4 p = 4.58*10-4 , CD8 p = 3.01*10-4 ; LC: CD19 p = 0.140, CD4 p = 0.0669, CD8 p = 0.0759)."
This is a commercial dye so details about specificity and structure are scarce but one thing to bear in mind is that many neutral lipid stains are not specific to LDs and if you do whole-cell fluorescence measurements with them you will pick up signal from other cellular neutral lipids as well, not just LDs. Plasma membrane is like 40% neutral lipid or something significant like that from memory btw. This is why the chemists we worked with in the LD paper are making alternatives that are intended to be more specific. Non-LD background is a huge issue with a lot of neutral lipid dyes. I wish they did some LD imaging to complement this or that more information about the dye was available from Thermo.
Would have been good to see the kinetics of T cell stimulation between individuals compared given that the measurements were taken at the same 5 day time point. You can have cells from one individual start waning in response earlier than others particularly with this length of time from what I understand.
"We suggest that this lymphocyte dysfunction, driven by oxidative and mitochondrial damage, acts as an “energy sink”, much as an active infection does, draining the body of available energy and giving rise to debilitating fatigue and other sequelae."
Do people with ME/CFS gain less weight with comparable dietary intake? Do they have altered blood glucose? (genuinely asking, I don't know off the top of my head)
