He et al 2026 — P2X7-mediated cGAS-STING activation in chronic stress

One-paragraph summary

Mouse-model mechanistic study demonstrating that chronic restraint stress activates microglial P2X7 receptors in the hippocampus, which in turn cause mitochondrial damage, mtDNA release into the cytosol, and cGAS-STING pathway activation — producing TBK1/IRF3 phosphorylation, type I IFN, and pro-inflammatory cytokines, ultimately driving depressive-like behavior. Pharmacological inhibition at either of two pathway points blocks the chain: P2X7 inhibition (JNJ-47965567) and STING inhibition (H-151) both attenuate neuroinflammation and rescue depressive-like behavior. In vitro confirmation in BV2 microglia shows that LPS stimulation reproduces the same mtDNA-release / cGAS-STING activation cascade, and P2X7 knockdown blocks it. For the project's HERV-mitochondrial-inflammation loop, this paper supplies a parallel upstream entry point — chronic stress (a known FM trigger that the H2 chain explicitly invokes) can drive the same mtDNA → cGAS-STING → type I IFN amplification step that HERV-W ENV drives via the circ_0001810/AK2 pathway. The two upstream paths (HERV-driven and stress-P2X7-driven) converge on the same downstream amplifier, which has implications for both biomarker interpretation (an ISG signature could reflect either upstream driver in an FM patient) and therapy (STING inhibition would interrupt the loop regardless of which upstream path initiated it).

Claims as triples

• sustained_stress — causes → mast_cell_activation [evidence: chronic restraint stress → microglial P2X7 activation, conceptually adjacent to MC activation under stress; confidence: bridging]
• sustained_stress — causes → mtDNA [evidence: mouse-model mtDNA release under chronic stress; confidence: emerging]
• mtDNA — causes → cGAS_STING_pathway [evidence: in vivo + in vitro mtDNA-release-driven cGAS-STING activation; confidence: established (already in ontology, this paper reinforces)]
• cGAS_STING_pathway — responds_to → STING_inhibitor [evidence: H-151 attenuates neuroinflammation + behavior in mice; confidence: established (reinforces existing edge)]
• microglia — modulates → cGAS_STING_pathway [evidence: microglial P2X7 → mitochondrial damage chain; confidence: emerging]
• cGAS_STING_pathway — causes → depression [evidence: pathway inhibition rescues depressive-like behavior; confidence: emerging]

Methods note

In vivo: chronic restraint stress paradigm in mice (standard model of stress-induced depressive-like phenotype). Hippocampus harvested for protein/mRNA analysis: phosphorylated STING and IRF3, pro-inflammatory cytokines. Behavioral testing via standard depression-relevant assays. Pharmacological intervention arms: P2X7 antagonist JNJ-47965567 and STING inhibitor H-151. In vitro: BV2 microglia with LPS stimulation; P2X7 siRNA knockdown and pharmacological inhibition; mtDNA release quantification; Western for STING/IRF3 phosphorylation.

Limitations

• Mouse model. Translation to FM specifically is by mechanistic analogy, not direct demonstration. The depressive-like phenotype is the readout, not pain or fatigue.
• Single laboratory's finding. Independent replication of the P2X7 → mtDNA release → cGAS-STING chain in chronic-stress models would strengthen the claim.
• Pathway connectivity vs. quantitative contribution. The paper shows the pathway operates; it does not establish what fraction of stress-driven neuroinflammation goes through this route vs. parallel mechanisms.
• No FM-cohort data. Whether FM patients (HERV-W-positive or otherwise) show elevated P2X7 expression in monocytes / microglia is open.

Open questions raised

• Do FM patients show elevated microglial P2X7 expression on TSPO-PET-positive scans, or on PBMC monocyte panels? Tractable in any FM cohort with stored PBMCs.
• Does P2X7 antagonism (JNJ-47965567 or analogues) attenuate FM symptoms preferentially in stress-trigger-onset FM subset? Cheap pilot; safety profile of P2X7 antagonists is reasonable.
• Are the HERV-driven and stress-P2X7-driven cGAS-STING activation paths additive or synergistic in FM patients with both upstream features?

Triangulation notes

• Adds a parallel upstream entry to the HERV-mitochondrial-inflammation loop. The loop document (synthesis/herv-mitochondrial-inflammation-loop.md) currently has HERV-W ENV → mitochondrial damage → mtDNA → cGAS-STING as the primary driver. He et al 2026 adds a stress-driven entry: sustained stress → microglial P2X7 → mitochondrial damage → mtDNA → cGAS-STING. Same downstream amplifier, different upstream driver.
• Reinforces STING inhibition as a chain-agnostic intervention. A STING inhibitor would interrupt the IFN-amplification step regardless of whether the upstream is HERV reactivation, P2X7-mediated stress signalling, or another mtDNA-release driver. This makes STING inhibition more attractive than HERV-W-targeted therapy (temelimab) as a broad-spectrum interrupter.
• Bridges H2 (mast cell, post-viral / stress) and the HERV-mito-loop framework. Stress-trigger FM, which has historically been H2-mapped, may operate through the same downstream amplifier as HERV-positive FM, with P2X7 as the H2-side entry node.
• Compatible with Coluzzi 2025 TSPO-PET findings. Microglial activation visible on TSPO-PET in nociplastic pain may partly reflect P2X7-driven cGAS-STING activation in the microglial compartment. Tractable to investigate by adding monocyte P2X7 RT-qPCR to the biomarker-mapping cohort.

Bridges

• Strengthens the HERV-mito-loop framework by establishing a chain-redundancy property: the loop's downstream amplifier (cGAS-STING → type I IFN) can be entered from multiple upstream drivers, which is what would explain the broad post-trigger durability across heterogeneous FM patients.
• New candidate B13 — chronic stress ↔ FM via P2X7-mediated cGAS-STING activation. Distinct from the H2-MC-activation route; this is microglial rather than mast-cell-mediated.