Can infection-related immune activation promote neuroinflammation and autoantibodies?

Infections can trigger systemic immune responses that extend to the central nervous system and alter self-reactive immunity. The claim is supported, with the strongest direct human data from SARS-CoV-2 cohorts and more causal mechanistic evidence from animal models.

Clinical and longitudinal evidence

• In a paired CSF/serum COVID-19 cohort (n=38; mean age 68.6 years), CSF IL-6, IL-8, IL-16, CXCL10, CCL1, and C5/C5a were elevated. CSF/serum indices suggested substantial blood-to-CSF entry of IL-6, IL-16, and CXCL10, with mild-to-moderate blood–CSF barrier dysfunction in some patients.
• Longitudinal cohorts with pre-infection samples found newly emergent autoantibodies after SARS-CoV-2 infection. Among baseline-negative individuals who developed these antibodies, 60% remained elevated at 12 months; persistence was more frequent following severe COVID-19.
• These observations demonstrate post-infectious inflammatory and serologic changes, not that autoantibodies necessarily cause neurologic or autoimmune disease.

Mechanistic evidence

• Molecular mimicry: Pathogen-directed antibodies can cross-react with structurally similar self-antigens. In Sydenham chorea, antibodies/CSF react with neural lysoganglioside and dopamine-receptor targets and activate neuronal CaMKII. In animal models, Campylobacter jejuni ganglioside-mimicking lipooligosaccharides induced cross-reactive antibodies and neural injury.
• Bystander activation: Infection-driven innate signaling, cytokines, antigen-presenting-cell activation, and costimulation can activate autoreactive lymphocytes without cognate T-cell-receptor signaling. In mice, LPS induced experimental autoimmune encephalomyelitis and relapses, with autoreactive CD4 T-cell proliferation and cytokine production dependent on LPS-responsive cells and costimulation.
• Older animals show amplified brain HMGB1, TNF, IL-1β, C1q, and microglial responses after systemic E. coli infection, relevant to vulnerability in advanced age.

Bottom line

• Infection-related immune activation can promote neuroinflammatory processes and durable autoantibody emergence; molecular mimicry and bystander activation are credible contributing mechanisms. However, persistent antibodies, CSF cytokines, or glial-reactivity signals alone do not establish pathogenic autoimmunity or sustained CNS inflammation in an individual patient.