The study focused on post-COVID patients with neurological symptoms like brain fog, memory issues, or fatigue. They found: Elevated AT1-AA in serum and cerebrospinal fluid (CSF) Correlation with neurofilament light chain (NfL), a marker of axonal damage Signs of a compensatory

What are AT1-AA? Autoantibodies that act as agonists at the angiotensin II type 1 receptor (AT1R), which mediates pro-inflammatory, pro-thrombotic, and vasoconstrictive signals. Unlike typical antibodies, these lock the receptor in an “always on” state - driving inflammation and

NfL is a marker of axonal damage - its elevation in serum reflects ongoing or recent neural injury. In this study, NfL strongly correlated with AT1-AA levels. Suggesting that immune activation via RAS isn’t just inflammation - it may physically damage the brain.

The body tries to compensate - but often too late! In CSF, patients showed increased autoantibodies activating anti-inflammatory RAS receptors (AT2-AA, MasR-AA). This may reflect a feedback response to chronic AT1R stimulation. But in many patients, this compensatory axis isn’t

Strikingly, patients with the worst cognitive deficits had the highest levels of MasR-AA. This suggests the compensatory response may scale with injury - but fail to reverse it. Post-COVID cognitive issues may reflect measurable CNS damage.

These findings echo what we’ve seen in other diseases: Pre-eclampsia: AT1-AA drive endothelial damage Parkinson’s: AT1-AA found in serum & CSF HIV: chronic neuroinflammation, axonal loss Alzheimer’s: AT1R overactivity linked to hippocampal atrophy Long COVID may follow similar

So what are the implications? AT1-AA and NfL may serve as biomarkers for CNS-involved Long COVID Could stratify patients and guide care AT1 receptor blockers (eg telmisartan) could be repurposed - already studied in neurodegeneration

Big picture: Post-COVID is not a diagnostic trashbin. In some patients, it’s a biologically defined neuroinflammatory syndrome, with Persistent autoantibodies Axonal damage Failed CNS homeostasis And we can measure it.

Limitations? Yes - and they matter. Small cross-sectional study (n = 69). Subgroups (eg severe cognitive impairment) are even smaller. Causality can’t be established - yet. But the signal is real. And it’s consistent with prior research.

This doesn’t reinvent the wheel - it reinforces a signal we’ve seen again and again. AT1-AA, NfL, hippocampal atrophy, BBB disruption - these threads are converging! Meanwhile, public health hasn’t moved an inch. No screening. No follow-up. No guidelines. Just silence.

Bottom line: Some Long COVID patients may suffer persistent autoimmune RAS activation in the brain - a measurable, actionable form of CNS injury. We now have biomarkers. We have mechanisms. What we don’t have is urgency.

Rodriguez-Perez et al. (2025). Serum angiotensin type‑1 receptor autoantibodies and neurofilament light chain as markers of neuroaxonal damage in post‑COVID patients. Frontiers in Immunology. https://www.frontiersin.org/jo...