69: Immune-Mediated Mechanisms Underlying SARS-CoV-2 Spike�Induced Persistent Pain

Topic: Basic Science
Subtopic: Pain category (ICD-11), Chronic pain related to Long COVID, , , , , , , , , , Developing methodology/technology, Neuroimmunology, Assessment and Measurement of Pain/Nociception

Background and Aims: Persistent pain is a frequent and disabling feature of post-COVID-19 syndrome, yet its biological mechanisms remain poorly understood. Beyond viral replication, SARS-CoV-2 structural proteins can act as immunogenic triggers capable of inducing long-lasting neuroimmune alterations. While the Spike protein has been implicated in transient nociceptive effects, its role in sustained pain processing is unclear. Here, we investigated whether peripheral exposure to the SARS-CoV-2 Spike protein is sufficient to induce persistent pain-like behaviours and sought to identify the immune pathways and mediators underlying these sensory alterations.

Methods: Recombinant SARS-CoV-2 Spike protein was administered intraplantarly in mice. Pain-related behaviours, including mechanical and thermal sensitivity, and paw inflammation were monitored for up to 35 days. Pharmacological inhibition, immune cell depletion, and genetically modified mice were used to dissect underlying mechanisms. Inflammatory markers were quantified in peripheral tissue, serum, and spinal cord by qPCR, ELISA, and immunofluorescence. Calcium imaging was performed in cultured dorsal root ganglion neurons to assess direct neuronal activation by Spike.

Results: Spike injection induced acute paw inflammation followed by long-lasting bilateral mechanical and heat hypersensitivity. These effects required TLR4 signaling and were abolished by pharmacological TLR4 blockade or genetic TLR4 deficiency. Spike did not directly activate sensory neurons or induce neuronal injury markers, indicating an inflammation-driven mechanism. Peripheral inflammation was transient, whereas systemic and spinal cytokine levels remained elevated. Depletion of phagocytic cells or inhibition of T-cell co-stimulation fully prevented persistent hypersensitivity. Notably, Spike-induced inflammation and pain were absent in IFN-γ-deficient mice.

Conclusions: Our findings demonstrate that the SARS-CoV-2 Spike protein is sufficient to trigger persistent pain-like behaviours through a TLR4-dependent immune cascade rather than direct neuronal activation. This process involves phagocyte-driven antigen presentation, T-cell engagement, and sustained spinal neuroinflammation, with IFN-γ acting as a key mediator. These results reveal a mechanistic framework linking Spike-induced immune activation to long-lasting nociceptive sensitization, offering insights into the biological basis of post-COVID pain and highlighting immune pathways as potential therapeutic targets.

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Presenting Author: Robson da Costa
Submitting Author: Robson da Costa

Senior Author: Robson da Costa

IASP 2026 Global Year theme of Neuropathic Pain: No

• Bianca de Lima Almeida: MSc - UFRJ, Brazil
• Suelen Pereira: MSc - UFRJ, Brazil
• Louise C. Vitorino: PhD - UFRJ, Brazil
• Laura I. Primicheru: MSc - King´s College London
• Fernanda Capitanio Goldoni: MSc - UNIVALI, Brazil
• Ozana Kethilen França Fernandes: Bachellor of Pharmacy - UNIVALI, Brazil
• Giulia Lima Rasga: Bachelor of Pharmacy - UFRJ, Brazil
• Marina da Cruz Nunes: Bachelor in Pharmacy - UFRJ, Brazil
• Marianne Neves Manjavachi: PhD - UFRB, Brazil
• Claudia P. Figueiredo: PhD - UFRJ, Brazil
• Nara Lins Meira Quintão: PhD - UNIVALI, Brazil
• Stuart Bevan: PhD - King´s College London, UK
• Giselle F. Passos: PhD - UFRJ, Brazil