Induction of distinct neurologic disease manifestations during relapsing fever requires T lymphocytes

Area of Science:

• Neuroscience
• Immunology
• Infectious Disease

Background:

• Relapsing fever borreliosis is a systemic infection caused by Borrelia species.
• Central nervous system (CNS) involvement varies depending on the Borrelia species.
• Neurological manifestations can range from mild symptoms to severe paralysis.

Purpose of the Study:

• To investigate the role of T cells in the development of CNS disease during Borrelia hermsii infection in a murine model.
• To understand the mechanisms underlying Borrelia-induced neuropathogenesis.

Main Methods:

• Utilized a murine model of Borrelia hermsii infection.
• Compared disease progression in wild-type (Wt) mice and T cell-deficient mice (TCR-beta x delta(-/-)).
• Assessed CNS pathology, immune cell infiltration, and microglial activation via histopathology and flow cytometry.

Main Results:

• Borrelia hermsii infection led to significant CNS disease signs in Wt mice, including paralysis.
• T cell-deficient mice showed no CNS disease, despite comparable bacteremia levels to Wt mice.
• Reduced immune cell infiltration and microglial activation were observed in the spinal cords of T cell-deficient mice.
• CNS disease severity was influenced by the Borrelia strain and the host's ability to control bacteremia (e.g., CD14(-/-) mice showed more severe disease).

Conclusions:

• T cells are essential for the induction of Borrelia-induced neuropathogenesis.
• The study highlights the critical role of T cell-mediated immunity in preventing or mediating CNS complications of relapsing fever borreliosis.
• Distinct neurological diseases arise during relapsing fever, with T cells playing a pivotal role.