Immune System Alterations in Depression across Baseline and Flu Vaccine Challenge

Area of Science:

• Immunology
• Neuroscience
• Genomics

Background:

• Major depression is associated with elevated inflammation.
• The impact of these immune perturbations on peripheral immune system functionality remains unclear.

Purpose of the Study:

• To investigate immune system functionality in major depression using single-cell RNA sequencing.
• To compare gene expression and cell populations in depressed patients versus healthy controls.

Main Methods:

• Single-cell RNA sequencing (scRNA-seq) of peripheral blood mononuclear cells (PBMCs).
• Analysis of gene expression and cell type proportions.
• Comparison between 9 depressed patients and 5 healthy controls at baseline.

Main Results:

• Downregulated T and B cell gene expression in depressed patients.
• Upregulated plasmablast, CD14 classical monocyte, and NK cell gene expression.
• Reduced CD4+ T, CD8+ T, plasmablasts, and NK cells; increased CD14 and CD16 monocytes and doublets in depressed individuals.

Conclusions:

• Depression is associated with significant transcriptomic and cellular immune alterations.
• Suggests impaired innate and adaptive immune responses at the molecular and cellular levels.
• Immune system dysfunction may play a role in major depression pathophysiology.