Tier 1 Sub-Research: T-Cell Mitochondrial Exhaustion Literature Supplementation

1 Kashatus2015 — ERK2 Phosphorylation of DRP1 at Ser616 Promotes Mitochondrial Fission

  • Full Citation:: Kashatus JA, Nascimento A, Myers LJ, Sher A, Byrne FL, Hoehn KL, Counter CM, Kashatus DF. Erk2 phosphorylation of Drp1 promotes mitochondrial fission and MAP kinase-driven tumor growth. Molecular Cell. 2015;57(3):537–551. (Kashatus et al. 2015)
  • DOI:: https://doi.org/10.1016/j.molcel.2015.01.002
  • PMID:: 25658205
  • Study Design:: Biochemical + functional: phosphosite mapping, Ser616→Ala mutagenesis, in vivo tumor model.
  • Key Findings::
    • ERK2 directly phosphorylates DRP1 at Ser616
    • Ser616→Ala mutation blocks ERK2-driven mitochondrial fission
    • ERK-DRP1 axis promotes MAP kinase-driven tumor growth
  • Relevance to ME/CFS T-cell model:: Canonical demonstration that ERK phosphorylates DRP1 at the activating Ser616 site. This is the molecular link connecting ROS→pERK to DRP1 activation in the hypothesized positive feedback loop. Never tested in immune cells.
  • Certainty:: 0.85 (Molecular Cell; rigorous biochemistry + functional validation)

2 Yu2020 — PGAM5 Phosphatase Modulates DRP1 Phosphorylation Balance

  • Full Citation:: Yu B, Ma J, Li J, Wang D, Wang Z, Wang S. Mitochondrial phosphatase PGAM5 modulates cellular senescence by regulating mitochondrial dynamics. Nature Communications. 2020;11:2549. (Yu et al. 2020)
  • DOI:: https://doi.org/10.1038/s41467-020-16355-0
  • PMID:: 32339784
  • Study Design:: Genetic knockout + biochemical: PGAM5 KO cells, phosphosite analysis, senescence assays.
  • Key Findings::
    • PGAM5 dephosphorylates DRP1 at Ser637 (inhibitory site, opposing Ser616 activation)
    • Loss of PGAM5 → DRP1 Ser616 dominance → persistent fission → cellular senescence
    • DRP1 Ser616/Ser637 phosphorylation ratio determines fission-fusion steady state
  • Relevance to ME/CFS T-cell model:: Establishes that a shift in DRP1 phospho-equilibrium toward Ser616 (away from Ser637) can be self-sustaining. If PGAM5 is impaired in ME/CFS (e.g., by oxidative damage), DRP1 remains locked in fission-promoting configuration even without ongoing trigger.
  • Certainty:: 0.80 (Nature Communications; genetic + biochemical validation)

3 Kaminski2012 — Mitochondrial ROS Activates ERK in T Lymphocytes

  • Full Citation:: Kaminski MM, Sauer SW, Klemke CD, Süss D, Okun JG, Krammer PH, Gülow K. Mitochondrial reactive oxygen species control T cell activation by regulating IL-2 and IL-4 expression. Journal of Immunology. 2010;184(9):4827–4841. (Kaminski et al. 2010)
  • DOI:: https://doi.org/10.4049/jimmunol.0903021
  • PMID:: 20351185
  • Study Design:: Pharmacological + genetic: mtROS modulation in primary human T cells; p-ERK measurement.
  • Key Findings::
    • Mitochondrial ROS activate ERK1/2 in T lymphocytes
    • Pharmacological mtROS reduction suppresses p-ERK and downstream cytokine production (IL-2, IL-4)
    • mtROS→ERK signaling is required for normal T-cell activation
  • Relevance to ME/CFS T-cell model:: Demonstrates that ROS→ERK activation is an operational pathway specifically in T cells — the cell type in which the DRP1-ROS-pERK loop is hypothesized. Extends the ERK→DRP1 Ser616 link (Kashatus 2015) into the immune compartment.
  • Certainty:: 0.70 (J Immunol; pharmacological + genetic validation in primary T cells)

4 Peng2016 — Glycolysis Produces Acetyl-CoA for Histone Acetylation in T-Cell Differentiation

  • Full Citation:: Peng M, Yin N, Chhangawala S, Xu K, Leslie CS, Li MO. Aerobic glycolysis promotes T helper 1 cell differentiation through an epigenetic mechanism. Science. 2016;354(6311):481–484. (Peng et al. 2016)
  • DOI:: https://doi.org/10.1126/science.aaf6284
  • PMID:: 27708054
  • Study Design:: Metabolic tracing + ChIP-seq: acetyl-CoA measurement, histone acetylation ChIP, pharmacological glycolysis inhibition.
  • Key Findings::
    • Glycolysis → acetyl-CoA → histone H3 acetylation at Ifng locus
    • Blocking glycolysis → reduced H3K9 acetylation → failed Th1 differentiation
    • Direct metabolic-to-chromatin coupling demonstrated in T cells
  • Relevance to ME/CFS T-cell model:: Biochemical precedent for metabolic-memory hypothesis: if mitochondrial failure reduces acetyl-CoA production, histone acetylation at exhaustion loci (TOX, EOMES) drops, locking in the exhausted program. The same enzyme-catalyzed pathway that controls Th1 differentiation also controls exhaustion state.
  • Certainty:: 0.90 (Science; metabolic tracing + ChIP-seq; rigorous validation)

5 Tyrakis2016 — αKG Metabolite Controls CD8+ T-Cell Fate via TET2

  • Full Citation:: Tyrakis PA, Palazon A, Macias D, et al. S-2-hydroxyglutarate regulates CD8+ T-lymphocyte fate. Nature. 2016;540:236–241. (Tyrakis et al. 2016)
  • DOI:: https://doi.org/10.1038/nature20165
  • PMID:: 27919066
  • Study Design:: Metabolomic + genetic: 2HG measurement in CD8+ T cells; TET2 modulation; memory differentiation assays.
  • Key Findings::
    • S-2HG produced by CD8+ T cells upon TCR stimulation promotes memory formation
    • S-2HG inhibits αKG-dependent TET2 demethylase
    • Mitochondrial metabolite availability (αKG/2HG balance) directly controls CD8+ differentiation
  • Relevance to ME/CFS T-cell model:: If ME/CFS mitochondrial dysfunction depletes αKG, TET2 activity drops → DNA hypermethylation at exhaustion/memory loci. This links mitochondrial TCA cycle failure to CD8+ epigenetic state via a defined enzyme — the missing mechanistic node in the metabolic-memory hypothesis.
  • Certainty:: 0.85 (Nature; genetic knockout + metabolic rescue)

6 Bailis2019 — Mitochondrial Metabolism Uncoupled from T-Cell Differentiation

  • Full Citation:: Bailis W, Shyer JA, Zhao J, et al. Distinct modes of mitochondrial metabolism uncouple T cell differentiation and function. Nature. 2019;571:403–407. (Bailis et al. 2019)
  • DOI:: https://doi.org/10.1038/s41586-019-1367-3
  • PMID:: 31270458
  • Study Design:: Isotope tracing + CRISPR screening in primary mouse and human T cells.
  • Key Findings::
    • T cells use two separable mitochondrial modes: TCA→OXPHOS (effector function) vs TCA→citrate export→acetyl-CoA (histone acetylation)
    • These modes can be uncoupled — a T cell can be ATP-competent but epigenetically locked
    • Citrate export via ACLY is rate-limiting for H3K27 acetylation at differentiation loci
  • Relevance to ME/CFS T-cell model:: Explains how ME/CFS CD8+ TEM cells could maintain baseline ATP (Missailidis 2020 Complex V compensation) while still being epigenetically locked in exhaustion — because acetyl-CoA export is a distinct metabolic mode that may be selectively impaired. This resolves the apparent paradox of normal resting ATP + chronic exhaustion state.
  • Certainty:: 0.90 (Nature; isotope tracing + CRISPR; rigorous validation)

7 Franco2020 — Metabolic-Epigenetic Regulation of T-Cell Exhaustion (Review)

  • Full Citation:: Franco F, Jaccard A, Romero P, Ho PC. Metabolic and epigenetic regulation of T-cell exhaustion. Nature Metabolism. 2020;2:1001–1012. (Franco et al. 2020)
  • DOI:: https://doi.org/10.1038/s42255-020-00283-y
  • PMID:: 32929201
  • Study Design:: Comprehensive review synthesizing primary literature.
  • Key Findings::
    • T-cell exhaustion is both a metabolic AND epigenetic state
    • Exhausted T cells acquire distinct metabolic profile (suppressed glycolysis, FAO dependence) stabilized by chromatin remodeling
    • Key metabolic-epigenetic nodes: acetyl-CoA (histone acetylation), αKG (TET2 demethylation), SAM/SAH ratio (DNA methylation)
  • Relevance to ME/CFS T-cell model:: Formalizes the connection between mitochondrial metabolism and exhaustion chromatin state — the same connection the metabolic-memory hypothesis posits for ME/CFS, but triggered by mitochondrial failure rather than chronic antigen. Identifies measurable intermediate nodes for validating the metabolic-memory model.
  • Certainty:: 0.70 (Nature Metabolism review; authoritative synthesis of primary data)

8 Pauken2016 — Epigenetic Stability of Exhausted T Cells Limits Reversal by PD-1 Blockade

  • Full Citation:: Pauken KE, Sammons MA, Odorizzi PM, et al. Epigenetic stability of exhausted T cells limits durability of reinvigoration by PD-1 blockade. Science. 2016;354(6316):1160–1165. (Pauken et al. 2016)
  • DOI:: https://doi.org/10.1126/science.aaf2807
  • PMID:: 27789796
  • Study Design:: ATAC-seq + ChIP-seq on exhausted CD8+ T cells before/after PD-1 blockade in LCMV model.
  • Key Findings::
    • Exhausted CD8+ T cells acquire epigenetically stable chromatin landscape distinct from memory/effector
    • PD-1 blockade transiently reinvigorates but does NOT erase exhaustion epigenome
    • TCF7 locus chromatin closure is a hallmark feature of terminal exhaustion
  • Relevance to ME/CFS T-cell model:: If CD8+ TEM cells in ME/CFS have undergone similar chromatin locking (as Iu 2024 ATAC-seq data suggest), metabolic interventions alone may not fully reverse exhaustion — combined metabolic + epigenetic strategies may be required. Explains why PD-1 blockade alone may be insufficient.
  • Certainty:: 0.90 (Science; rigorous epigenomic profiling)

9 Siddiqui2019 — TCF1+ Progenitor Exhausted CD8+ T Cells Respond to Checkpoint Blockade

  • Full Citation:: Siddiqui I, Schaeuble K, Chennupati V, et al. Intratumoral Tcf1+PD-1+CD8+ T cells with stem-like properties promote tumor control in response to vaccination and checkpoint blockade immunotherapy. Immunity. 2019;50(1):195–211.e10. (Siddiqui et al. 2019)
  • DOI:: https://doi.org/10.1016/j.immuni.2018.12.021
  • PMID:: 30635237
  • Study Design:: Single-cell RNA-seq + ATAC-seq: intratumoral CD8+ T-cell subpopulations; TCF1+ vs TCF1− functional assays.
  • Key Findings::
    • TCF1 (encoded by TCF7) identifies progenitor exhausted CD8+ subset that self-renews
    • Only TCF1+PD-1+ progenitor cells respond to PD-1 blockade
    • TCF1− cells are terminally exhausted and non-responsive
  • Relevance to ME/CFS T-cell model:: TCF7 expression levels in CD8+ TEM cells (documented by Iu 2024) may stratify ME/CFS patients into reversible (TCF7-high) vs terminal (TCF7-low) exhaustion — the same biomarker framework used in cancer immunotherapy. This has direct prognostic implications without needing checkpoint inhibitors.
  • Certainty:: 0.85 (Immunity; scRNA-seq + functional validation)

10 Miller2019 — Subsets of Exhausted CD8+ T Cells in Tumor Control

  • Full Citation:: Miller BC, Sen DR, Al Abosy R, et al. Subsets of exhausted CD8+ T cells differentially mediate tumor control and respond to checkpoint blockade. Nature Immunology. 2019;20(3):326–336. (Miller et al. 2019)
  • DOI:: https://doi.org/10.1038/s41590-019-0312-6
  • PMID:: 30778252
  • Study Design:: scRNA-seq + ATAC-seq + functional assays on CD8+ TILs from murine and human tumors.
  • Key Findings::
    • Exhausted CD8+ T cells exist on a continuum: TCF7+PD-1+ progenitor → TIM-3+ terminally exhausted
    • Polyclonal exhaustion (multiple TCR specificities) implies non-antigen-selective trigger
    • Only progenitor subset proliferates upon PD-1 blockade
  • Relevance to ME/CFS T-cell model:: Polyclonal exhaustion pattern is consistent with a metabolic/mitochondrial trigger (not chronic antigen) — the model proposed for ME/CFS (immune suppression, not activation-driven exhaustion per Petrov 2026). If the ME/CFS CD8+ exhaustion is polyclonal (testable by TCR sequencing), this supports a metabolic rather than antigenic driver.
  • Certainty:: 0.85 (Nature Immunology; multi-modal sc profiling)

12 Younes2016 — HIV+ CD4+ T-Cell Mitochondrial Dysfunction Persists on ART

  • Full Citation:: Younes SA, Talla A, Pereira Ribeiro S, et al. Cycling CD4+ T cells in HIV-infected immune non-responders have mitochondrial dysfunction. Journal of Clinical Investigation. 2016;126(11):4363–4374. (Younes et al. 2016)
  • DOI:: https://doi.org/10.1172/JCI88694
  • PMID:: 27608061
  • Study Design:: Cross-sectional: metabolic flux analysis (Seahorse), mitochondrial phenotyping in CD4+ T cells from ART-suppressed HIV+ patients.
  • Key Findings::
    • HIV+ immune non-responders (viral suppression on ART, CD4 < 350): reduced mitochondrial mass, decreased OXPHOS, increased ROS
    • Mitochondrial dysfunction persists despite undetectable viral load
    • Impaired metabolic reprogramming upon activation — same demand-response failure pattern as ME/CFS
  • Relevance to ME/CFS T-cell model:: Strongest clinical precedent for post-viral T-cell mitochondrial dysfunction without ongoing viral replication. Demonstrates that clinical immune failure in a controlled post-viral state is partly a mitochondrial-metabolic problem.
  • Certainty:: 0.80 (JCI; functional metabolic assays + mito phenotyping)

13 DeRosa2000 — NAC Replenishes Glutathione in HIV (Clinical Precedent for Antioxidant T-Cell Restoration)

  • Full Citation:: De Rosa SC, Zaretsky MD, Dubs JG, et al. N-acetylcysteine replenishes glutathione in HIV infection. European Journal of Clinical Investigation. 2000;30(10):915–929. (De Rosa et al. 2000)
  • DOI:: https://doi.org/10.1046/j.1365-2362.2000.00736.x
  • PMID:: 11029607
  • Study Design:: Clinical trial: NAC supplementation with GSH/cysteine measurement and CD4/CD8 tracking.
  • Key Findings::
    • NAC increased plasma cysteine and GSH levels in HIV+ patients
    • Improved CD4+ T-cell counts and reduced immune activation markers
    • Glutathione redox axis identified as rate-limiting for T-cell survival in chronic HIV
  • Relevance to ME/CFS T-cell model:: Clinical precedent for antioxidant-based T-cell restoration in a post-viral state via GSH-redox axis. Mechanism consistent with Gil 2024 nebulized antioxidant case series, but with better-controlled evidence base. Supports the model that breaking the DRP1-ROS-pERK loop at the ROS node could partially restore T-cell function.
  • Certainty:: 0.55 (Eur J Clin Invest; well-controlled mechanistic trial; modest n)

14 Schank2021 — HIV- and ART-Induced Mitochondrial Dysfunction Review

  • Full Citation:: Schank M, Zhao J, Moorman JP, Yao ZQ. The impact of HIV- and ART-induced mitochondrial dysfunction in cellular senescence and aging. Cells. 2021;10(1):174. (Schank et al. 2021)
  • DOI:: https://doi.org/10.3390/cells10010174
  • PMID:: 33467623
  • Study Design:: Comprehensive narrative review.
  • Key Findings::
    • Both HIV proteins and ART drugs induce mitochondrial dysfunction: mtDNA depletion, ETC inhibition, ROS, impaired mitophagy
    • Mitochondrial pathology persists after viral suppression and contributes to accelerated immune aging
    • Dual-senescence-exhaustion flow phenotyping (CD28/CD57 + PD-1/TIM-3) is a standard tool in HIV research
  • Relevance to ME/CFS T-cell model:: Provides the technical roadmap (mtDNA qPCR, mitophagy markers, ETC complex assays, dual-phenotype flow panel) that ME/CFS research should adopt to characterize CD8+ mitochondrial dysfunction. Documents full spectrum of post-viral mitochondrial pathology mechanisms.
  • Certainty:: 0.65 (Cells; comprehensive review; strong literature base)

References

Bailis, W., J. A. Shyer, J. Zhao, J. C. G. Canaveras, F. J. Al Khazal, R. Qu, H. R. Steach, et al. 2019. “Distinct Modes of Mitochondrial Metabolism Uncouple T Cell Differentiation and Function.” Nature 571: 403–7. https://doi.org/10.1038/s41586-019-1367-3.
De Rosa, S. C., M. D. Zaretsky, J. G. Dubs, M. Roederer, M. Anderson, A. Green, D. Mitra, et al. 2000. “N-acetylcysteine Replenishes Glutathione in HIV Infection.” European Journal of Clinical Investigation 30 (10): 915–29. https://doi.org/10.1046/j.1365-2362.2000.00736.x.
Deguit, C. D. T., M. Hough, R. Hoh, M. Krone, C. D. Pilcher, J. N. Martin, S. G. Deeks, T. J. Henrich, P. W. Hunt, and L. C. Ndhlovu. 2022. “Some Like It TOX: CD8+ T-Cell Stemness and Exhaustion Are Linked in HIV.” AIDS 36 (14): 1981–88.
Franco, F., A. Jaccard, P. Romero, Y. R. Yu, and P. C. Ho. 2020. “Metabolic and Epigenetic Regulation of T-Cell Exhaustion.” Nature Metabolism 2: 1001–12. https://doi.org/10.1038/s42255-020-00283-y.
Kaminski, M. M., S. W. Sauer, C. D. Klemke, D. Süss, J. G. Okun, P. H. Krammer, and K. Gülow. 2010. “Mitochondrial Reactive Oxygen Species Control T Cell Activation by Regulating IL-2 and IL-4 Expression.” Journal of Immunology 184 (9): 4827–41. https://doi.org/10.4049/jimmunol.0903021.
Kashatus, Jennifer A., A. Nascimento, L. J. Myers, A. Sher, F. L. Byrne, K. L. Hoehn, C. M. Counter, and D. F. Kashatus. 2015. “Erk2 Phosphorylation of Drp1 Promotes Mitochondrial Fission and MAP Kinase-Driven Tumor Growth.” Molecular Cell 57 (3): 537–51. https://doi.org/10.1016/j.molcel.2015.01.002.
Miller, B. C., D. R. Sen, R. Al Abosy, K. Bi, Y. V. Virkud, M. W. LaFleur, K. B. Yates, et al. 2019. “Subsets of Exhausted CD8+ T Cells Differentially Mediate Tumor Control and Respond to Checkpoint Blockade.” Nature Immunology 20 (3): 326–36. https://doi.org/10.1038/s41590-019-0312-6.
Pauken, K. E., M. A. Sammons, P. M. Odorizzi, S. Manne, J. Godec, O. Khan, A. M. Drake, et al. 2016. “Epigenetic Stability of Exhausted T Cells Limits Durability of Reinvigoration by PD-1 Blockade.” Science 354 (6316): 1160–65. https://doi.org/10.1126/science.aaf2807.
Peng, M., N. Yin, S. Chhangawala, K. Xu, C. S. Leslie, and M. O. Li. 2016. “Aerobic Glycolysis Promotes T Helper 1 Cell Differentiation Through an Epigenetic Mechanism.” Science 354 (6311): 481–84. https://doi.org/10.1126/science.aaf6284.
Postow, M. A., R. Sidlow, and M. D. Hellmann. 2018. “Immune-Related Adverse Events Associated with Immune Checkpoint Blockade.” New England Journal of Medicine 378 (2): 158–68. https://doi.org/10.1056/NEJMra1703481.
Schank, M., J. Zhao, J. P. Moorman, and Z. Q. Yao. 2021. “The Impact of HIV- and ART-Induced Mitochondrial Dysfunction in Cellular Senescence and Aging.” Cells 10 (1): 174. https://doi.org/10.3390/cells10010174.
Siddiqui, I., K. Schaeuble, V. Chennupati, S. A. Fuertes Marraco, S. Calderon-Copete, D. Pais Ferreira, S. J. Carmona, et al. 2019. “Intratumoral Tcf1+PD-1+CD8+ T Cells with Stem-Like Properties Promote Tumor Control in Response to Vaccination and Checkpoint Blockade Immunotherapy.” Immunity 50 (1): 195–211.e10. https://doi.org/10.1016/j.immuni.2018.12.021.
Tyrakis, P. A., A. Palazon, D. Macias, K. L. Lee, A. T. Phan, P. Veliça, J. You, et al. 2016. “S-2-hydroxyglutarate Regulates CD8+ T-Lymphocyte Fate.” Nature 540: 236–41. https://doi.org/10.1038/nature20165.
Younes, S. A., A. Talla, S. Pereira Ribeiro, E. V. Saidakova, L. B. Korolevskaya, K. V. Shmagel, C. L. Shive, et al. 2016. “Cycling CD4+ T Cells in HIV-Infected Immune Non-Responders Have Mitochondrial Dysfunction.” Journal of Clinical Investigation 126 (11): 4363–74. https://doi.org/10.1172/JCI88694.
Yu, Bo, J. Ma, J. Li, D. Wang, Z. Wang, and S. Wang. 2020. “Mitochondrial Phosphatase PGAM5 Modulates Cellular Senescence by Regulating Mitochondrial Dynamics.” Nature Communications 11: 2549. https://doi.org/10.1038/s41467-020-16355-0.