2026 — Azcue — autoantibodies against GPCRs in PCC and ME/CFS
One-paragraph summary
Cross-sectional cohort comparison of plasma autoantibodies against α1, β1, β2 adrenergic and M1-M4 muscarinic receptors across 96 post-COVID-condition (PCC) patients, 59 ME/CFS patients, and 36 healthy controls. ELISA measurement, autonomic function assessed by COMPASS-31, Sudoscan, deep-breathing / Valsalva / tilt-table, and heart rate variability. Cognitive performance assessed across attention, fluency, processing speed, memory, visuoconstruction, perception, and executive functions. Key empirical results: β2-adrenergic AAb titers significantly higher in ME/CFS vs both PCC and HCs (F = 3.15, p = 0.046); PCC patients showed more borderline/pathological M3-muscarinic AAbs vs HCs; β2 AAbs correlated with autonomic symptoms in PCC (r = 0.27, p = 0.048) and sympathovagal imbalance in ME/CFS (r = 0.45, p = 0.001); in ME/CFS, M1/M3/M4 muscarinic AAb titers positively correlated with verbal and working memory performance. For the project, this paper provides head-to-head empirical differentiation of the autoantibody profile between PCC and ME/CFS — directly informing biomarker-mapping cohort dimension #7 (autoantibody panel) and providing the patient-selection logic by which Oesch-Régeni 2025's plasmapheresis+IVIG approach (used β2-AR / M3-muscarinic AAb positivity as inclusion criterion) can be extended into PCC vs ME/CFS stratification.
Claims as triples
beta2_adrenergic_autoantibody — present_in → me_cfs[evidence: ME/CFS vs HCs and vs PCC, F=3.15 p=0.046; confidence: emerging]m3_muscarinic_autoantibody — present_in → post_covid_syndrome[evidence: borderline/pathological more frequent in PCC vs HCs; confidence: emerging]beta2_adrenergic_autoantibody — correlates_with → autonomic_dysregulation[evidence: r=0.27 p=0.048 in PCC, r=0.45 p=0.001 sympathovagal in ME/CFS; confidence: emerging]muscarinic_autoantibody — correlates_with → cognitive_dysfunction[evidence: M1/M3/M4 titers positively correlate with verbal and working memory in ME/CFS; confidence: emerging]autoantibody_panel — differentiates → pcc_vs_mecfs_phenotype[evidence: distinct profile pattern between conditions; confidence: emerging]
Triangulation notes
- Direct empirical anchor for Hypothesis 3 (autoimmune-microbiome chain) cure-path stratification. Oesch-Régeni 2025 plasmapheresis+IVIG used β2-AR / M3-muscarinic AAb positivity as patient-selection criterion; Azcue provides the population-level prevalence data that supports extending the same stratification into the PCC vs ME/CFS subset distinction.
- Differentiates PCC from ME/CFS at the molecular biomarker level — the project's three-axis cube treats PCC and ME/CFS as related but distinct conditions; this paper provides empirical AAb-profile data supporting that distinction.
- Useful counterweight against van der Spek 2026's CRPS-non-specificity result — autonomic-receptor AAbs are not CRPS-specific (van der Spek) but appear to differ in profile between PCC and ME/CFS (Azcue). The disease specificity is in the pattern, not the absolute presence.
Open questions raised
- Are the M1/M3/M4 muscarinic AAb titers in ME/CFS correlating with better or worse cognitive performance? (Abstract says "positively correlated with verbal and working memory performance" — needs full-paper read for direction interpretation.)
- Does the β2-AR-high ME/CFS subset overlap with the Sotzny 2022 / Wirth & Scheibenbogen 2020 vasoconstrictive-FM-subtype empirical findings?
- Would an FcRn-blocker arm (efgartigimod / rozanolixizumab, Shi & Clark 2025) reduce these AAb titers proportionally to their pathological role?