Interleukin-6 Disrupts Synaptic Plasticity and Impairs Tissue Damage Compensation in Multiple Sclerosis

Area of Science:

• Neuroscience
• Immunology
• Clinical Neurology

Background:

• Synaptic plasticity aids in mitigating brain damage and compensating for new lesions in multiple sclerosis (MS).
• Inflammation, particularly involving interleukin-6 (IL-6), may negatively impact disease progression in relapsing-remitting MS (RR-MS).

Purpose of the Study:

• To investigate if IL-6 affects synaptic plasticity.
• To determine if IL-6 influences the brain's compensatory mechanisms for damage in MS.
• To correlate IL-6 levels with disease activity and progression in RR-MS.

Main Methods:

• In vitro experiments assessing IL-6's effect on long-term potentiation (LTP) in mouse hippocampal slices.
• Correlation analysis of cerebrospinal fluid (CSF) IL-6 levels with paired associative stimulation (PAS)-induced LTP-like effects in RR-MS patients.
• Longitudinal study examining the relationship between CSF IL-6 levels at diagnosis and subsequent disease activity in 150 RR-MS patients.

Main Results:

• IL-6 abolished in vitro LTP induction.
• A negative correlation was observed between CSF IL-6 concentrations and PAS effects in MS patients.
• Higher CSF IL-6 levels were associated with longer disease duration before diagnosis, increased inflammatory brain lesions, and greater clinical disease expression.

Conclusions:

• IL-6 interferes with synaptic plasticity mechanisms.
• This interference may impair the compensatory capacity for new brain lesions in RR-MS patients.
• Elevated IL-6 levels are linked to poorer disease outcomes in RR-MS.