Direct effects of prolonged TNF-α and IL-6 exposure on neural activity in human iPSC-derived neuron-astrocyte co-cultures.
Goshi, Noah, Lam, Doris, Bogguri, Chandrakumar et al. · Frontiers in cellular neuroscience · 2025 · DOI
Quick Summary
This study looked at how two inflammatory chemicals (TNF-α and IL-6) that are elevated in ME/CFS and long-COVID patients affect brain cells. Researchers grew human brain cells in the lab and exposed them to these chemicals for several days. They found that these inflammatory chemicals changed how the brain cells communicate with each other, which could help explain why patients experience cognitive problems like brain fog and difficulty concentrating.
Why It Matters
This research provides direct experimental evidence that elevated inflammatory cytokines present in ME/CFS patients can impair neural communication and activity, offering a potential biological mechanism for cognitive dysfunction in this population. Understanding these direct effects may guide development of targeted treatments to restore brain function and reduce cognitive symptoms.
Observed Findings
Low TNF-α concentrations (1-25 pg/mL) reduced burst duration within days in a concentration-independent manner, which recovered by day 7, without altering broader cytokine profiles or gene expression
High TNF-α concentrations (10-100 ng/mL) reduced spiking activity and triggered increased secretion of inflammatory cytokines (IL-1β, IL-4, CXCL-10)
IL-6 exposure significantly reduced the number of spikes occurring within bursts across a wide concentration range (1 pg/mL-10 ng/mL)
When TNF-α and IL-6 were combined, TNF-α effects dominated and IL-6-induced changes to electrophysiology were suppressed
Inferred Conclusions
Elevated inflammatory cytokines associated with post-viral conditions can directly impair neural communication and activity in ways that may contribute to cognitive symptoms
TNF-α plays a more dominant role than IL-6 in altering neural function when both are present, suggesting differential therapeutic targeting may be needed
The effects of these cytokines on neural function may occur through both direct inflammatory signaling and indirect secondary immune activation depending on concentration levels
Remaining Questions
How do these findings translate to the intact brain environment in ME/CFS patients, given the complexity of blood-brain barrier penetration and multi-cellular interactions?
Can reversing elevated TNF-α and IL-6 levels restore neural function and improve cognitive symptoms in patients?
What This Study Does Not Prove
This study does not prove that TNF-α and IL-6 are the sole causes of cognitive impairment in ME/CFS, nor does it establish whether reversing these cytokine elevations would restore cognitive function in patients. The findings are from laboratory-cultured cells and may not fully replicate the complex brain environment in living patients with ME/CFS.