Current concepts and controversies in prion immunopathology

Area of Science:

• Neuroscience
• Immunology
• Infectious Diseases

Background:

• Prion diseases, including scrapie in sheep and variant Creutzfeldt-Jakob disease in humans, often originate from peripheral exposure.
• Early prion accumulation occurs in the peripheral lymphoreticular system, particularly in germinal centers of lymph nodes and spleen.
• Follicular dendritic cells (FDCs) within germinal centers have been considered crucial for peripheral prion replication.

Purpose of the Study:

• To investigate the molecular requirements for prion replication in lymphoid organs.
• To examine the conditions necessary for prion passage through the mucosal-associated lymphoid system.
• To identify potential cellular mechanisms and sites involved in peripheral prion pathogenesis.

Main Methods:

• Analysis of prion replication competence in different cellular compartments of lymphoid organs.
• Investigation of transepithelial prion passage in the context of the mucosal-associated lymphoid system.
• Experimental models to assess prion accumulation and spread in the periphery.

Main Results:

• Efficient prion replication in mesenteric and inguinal lymph nodes can occur under specific conditions, independent of mature follicular dendritic cells (FDCs).
• M cells of the mucosal-associated lymphoid system are identified as a likely portal of entry for prion infection.
• The study elucidates alternative pathways for prion replication and spread in peripheral tissues.

Conclusions:

• Peripheral prion replication and pathogenesis involve complex interactions between stromal and lymphoid cells.
• M cells represent a critical entry point for peripheral prion diseases.
• The findings challenge the exclusive role of FDCs in peripheral prion replication, suggesting alternative cellular mechanisms are involved.