[When prions use the systems of communication between the immune system and the peripheral nervous system]

Prion disease pathogenesis has been largely studied since the inter-species transmissibility of the infectious protein (PrPSc), the oral uptake as natural route of infection and the exceptional implication in a problem of public health were highlighted. Two sequential preclinical stages are observed before the development of irreversible and fatal lesions in the central nervous system: the lymphoinvasion and the neuroinvasion. The first is characterized by the accumulation of PrPSc within lymphoid tissues and the second by PrPSc scattering the peripheral nervous system towards the central nervous system. The mechanisms involved in the communication between the immune and the peripheral nervous system are still debated. Recent studies even suggest that neuroinvasion can occur through the hematogenous route, independently of the peripheral nervous system. This review analyses (i) the role of immune cells, implicated in prion pathogenesis: dendritic cells as PrPSc vehicle, follicular dendritic cells as PrPSc accumulator and nerve fibres as PrPSc driver and (ii) the respective relations they maintain with peripheral nerve fibres to migrate to the brain.