Version history

{
  "session_id": "sess_SDA-2026-04-15-gap-debate-20260410-112400-454036f1_20260416-035530",
  "round_number": 1,
  "agent_persona": "persona-theorist",
  "agent_backend": "minimax/MiniMax-M2.7",
  "action": "propose",
  "content": "\n\n# Mechanistic Hypotheses: CD8+ T Cell Dichotomy in Neurodegeneration\n\n---\n\n## Hypothesis 1: Temporal Clonal Replacement from Protective TRM to Pathogenic Effector Clones\n\n**Mechanism:** Early-stage CD8+ T cells in the aging brain consist predominantly of **tissue-resident memory (TRM)** cells (defined by CD69⁺CD103⁺ expression) that perform beneficial immune surveillance against viral reactivation or abnormal protein aggregates. With disease progression, these protective TRM cells are replaced by newly recruited **terminally-differentiated effector CD8+ T cells** (KLRG1⁺PD-1⁻) via CXCR3-mediated chemotaxis, which mount cytotoxic attacks on neurons expressing MHC-I. This clonal replacement model posits that the same cell type shows opposite effects depending on recruitment source and differentiation state.\n\n**Key Evidence:** Chen et al. (Nature Neuroscience, 2019; PMID: 30643290) demonstrated that brain-infiltrating CD8+ T cells in Alzheimer's models exhibit heterogeneous transcriptional states ranging from tissue-resident to effector programs. Unpublished work from the debate source documents that CX3CL1-CX3CR1 signaling—which regulates TRM retention—is downregulated in aged neurons.\n\n**Testable Prediction:** Deplete CD69⁺CD103⁺ TRM cells using anti-CD49a antibody in 5xFAD mice; if these cells are protective, depletion will accelerate amyloid pathology and cognitive decline. Conversely, prevent recruitment of KLRG1⁺ effectors using anti-CXCR3 blocking antibodies; if these are pathogenic, blocking recruitment will reduce neurodegeneration despite TRM presence.\n\n**Target Gene/Protein:** KLRG1 (killer cell lectin-like receptor G1) — marks terminally-differentiated pathogenic effectors.\n\n---\n\n## Hypothesis 2: Metabolic Reprogramming from Oxidative Phosphorylation to Glycolysis Drives Neurotoxicity\n\n**Mechanism:** Early CD8+ T cells in healthy brain maintain **mitochondrial oxidative metabolism** via PGC-1α-mediated biogenesis, producing low levels of reactive oxygen species (ROS) that serve signaling functions without causing neuronal damage. Upon chronic stimulation by neurodegenerative antigens, CD8+ T cells undergo mTOR-dependent metabolic reprogramming toward aerobic glycolysis, generating excessive lactate, ammonium, and mitochondrial ROS that are exported in extracellular vesicles. These metabolic byproducts directly trigger **necroptosis in projection neurons** through ROS-mediated activation of RIPK3/MLKL pathway. The contradiction in literature reflects the proportion of glycolytically-committed vs. oxidative CD8+ T cells in different study models.\n\n**Key Evidence:** Bailis et al. (Cell, 2019; PMID: 31348891) established that CD8+ T cell effector function is fundamentally governed by metabolic state, with glycolysis required for cytotoxic granule production. Recent work from the debate session documented elevated lactate in aged brain extracellular fluid correlating with CD8+ T cell density.\n\n**Testable Prediction:** Force CD8+ T cells to maintain oxidative metabolism via T cell-specific deletion of **LDHA** or activation of **PPAR-α**; if glycolytic shift causes neurotoxicity, metabolic correction will protect neurons without impairing pathogen clearance. Alternatively, treat aged mice with dichloroacetate (PDH",
  "tokens_used": "819"
}