Systemic immunization with altered myelin basic protein peptide produces sustained antidepressant-like effects

Area of Science:

• Neuroimmunology
• Behavioral Neuroscience
• Pharmacology

Background:

• Immune dysregulation and inflammation are increasingly recognized as contributors to depressive symptoms.
• Myelin basic protein (MBP) and its derived peptides are implicated in neuroinflammatory processes.
• Altered peptide ligands (APLs) of MBP have been explored for their immunomodulatory potential.

Purpose of the Study:

• To evaluate the antidepressant-like effects of immunizing with specific MBP-derived APLs.
• To investigate the underlying mechanisms, focusing on inflammatory cytokines and key signaling molecules in the prefrontal cortex.
• To assess the efficacy of MBP APLs in preventing and reversing stress-induced depressive and anxiety-like behaviors.

Main Methods:

• Administration of MBP APLs (MBP_87-99[A⁹¹, A⁹⁶], MBP_87-99[R⁹¹, A⁹⁶]) in rodent models of depression.
• Behavioral testing including forced swim test and learned helplessness paradigm.
• Assessment of chronic unpredictable stress (CUS) effects on behavior, cytokine production, microglial activation, and expression of p11, pCREB, and BDNF in the prelimbic cortex (PrL).

Main Results:

• MBP_87-99[A⁹¹, A⁹⁶] administration demonstrated significant antidepressant-like effects, reducing immobility and improving performance in learned helplessness tasks.
• This APL prevented and reversed CUS-induced depressive and anxiety-like behaviors, while MBP_87-99[R⁹¹, A⁹⁶] exacerbated anxiety.
• MBP_87-99[A⁹¹, A⁹⁶] blocked CUS-induced increases in proinflammatory cytokines and microglial activation in the PrL, and restored deficits in p11, pCREB, and BDNF.

Conclusions:

• Immunization with MBP_87-99[A⁹¹, A⁹⁶] confers prolonged antidepressant-like effects in rats, mediated by the modulation of inflammatory factors and p11 signaling in the PrL.
• These findings highlight the role of immune-neural interactions in stress response and suggest MBP APLs as a potential therapeutic strategy for depression.
• The study underscores the therapeutic potential of targeting neuroinflammation via specific immune modulations for psychiatric disorders.