Neonatal vaccination with bacillus Calmette-Guérin and hepatitis B vaccines modulates hippocampal synaptic plasticity...

Area of Science:

• Neuroscience
• Immunology
• Vaccine Research

Background:

• Immune system activation influences neural functions, including synaptic transmission.
• Neonatal vaccination is a critical public health intervention with potential neurological implications.

Purpose of the Study:

• To investigate the effects of neonatal Bacille Calmette-Guérin (BCG) and Hepatitis B virus (HBV) vaccination on hippocampal synaptic plasticity in rats.
• To explore the relationship between peripheral immune responses and neurotrophic factors in the hippocampus post-vaccination.

Main Methods:

• Rats were vaccinated neonatally with BCG or HBV.
• Hippocampal synaptic plasticity was assessed.
• Peripheral and hippocampal cytokine levels (IFN-γ, IL-4, IL-1β, IL-6, TNF-α) were measured.
• Levels of brain-derived neurotrophic factor (BDNF) and insulin-like growth factor 1 (IGF-1) in the hippocampus were quantified.

Main Results:

• BCG vaccination significantly enhanced hippocampal synaptic plasticity.
• HBV vaccination markedly hampered hippocampal synaptic plasticity.
• Vaccination altered peripheral cytokine balance, favoring T helper type 1/T helper type 2 responses.
• Peripheral IFN-γ:IL-4 ratio positively correlated with hippocampal BDNF and IGF-1.
• BCG increased hippocampal IFN-γ, IL-4, BDNF, and IGF-1, while decreasing IL-1β, IL-6, and TNF-α.
• HBV induced opposite effects on hippocampal inflammatory markers and neurotrophic factors.

Conclusions:

• Neonatal BCG vaccination promotes hippocampal synaptic plasticity and favorable neurotrophic/inflammatory profiles.
• Neonatal HBV vaccination impairs hippocampal synaptic plasticity and exacerbates neuroinflammation.
• Cytokine balance and neurotrophic factors are key mediators linking peripheral immune responses to central nervous system plasticity after neonatal vaccination.