Can Borrelia infection drive persistent inflammation and neural autoimmunity?

Borrelia infection can generate durable inflammatory and broad immune activation, but the proposed progression from infection to pathogenic neural autoantibodies or clinical neuroinflammation remains mechanistically credible rather than established in most patients.

Clinical and inflammatory evidence

• Persistent immune activity is best documented in antibiotic-refractory Lyme arthritis: synovial tissue/fluid shows TNF-α, IL-1β, IFN-γ, and interferon-response signatures, including when Borrelia PCR is negative.
• In neuroborreliosis, inflammation usually declines substantially after antibiotics. In a 79-patient longitudinal study, CSF immune responses largely resolved and no longer correlated with symptoms. Some patients show residual signals—e.g., persistent CSF IL-17A, higher IL-17A among slower recoverers, or occasional CXCL13—but these are not reliable evidence of ongoing infection.
• In a 1,135-patient cohort, baseline symptoms, functional status, and psychosocial factors predicted persistent symptoms more strongly than measured immune factors.

Mechanistic evidence

• Molecular mimicry has direct but limited support. In one acute Lyme encephalitis case, a CSF CD4+ T-cell clone recognized both Borrelia peptides and CNPase, a CNS myelin protein. Experimental Borrelia-directed antibodies have also bound peripheral nerve fibers and CNS neurons.
• Bystander activation is more firmly demonstrated: B. burgdorferi lipoproteins drive B-cell proliferation and immunoglobulin production via TLR2/TLR1 independently of B-cell-receptor specificity; infected mice develop broad B-cell expansion and hypergammaglobulinemia.
• Neural models show that live or nonviable Borrelia can induce inflammatory mediators and apoptosis in oligodendrocytes, brain, and nerve-root explants, providing a separate route to neural inflammation.

Bottom line

• Borrelia can cause persistent, context-dependent inflammation and robust polyclonal immune activation. Molecular mimicry and bystander activation are plausible contributors to neural autoreactivity and neuroinflammation, but current evidence does not show that they commonly produce pathogenic neural autoantibodies, neural injury, or persistent neurologic disease in humans.