Causal Associations Between Immune Cell-Specific Gene Expression and Major Depressive Disorder: A Single-Cell...

Area of Science:

• Immunology
• Psychiatry
• Genetics

Background:

• Major depressive disorder (MDD) is a common psychiatric condition linked to immune system dysfunction.
• Understanding the genetic basis of immune cell involvement in MDD is crucial for developing targeted therapies.

Purpose of the Study:

• To investigate the causal relationship between gene expression in specific immune cell types and MDD.
• To identify novel molecular targets for precision immunotherapy in MDD.

Main Methods:

• Integrated single-cell cis-eQTL data with MDD GWAS summary statistics.
• Employed single-cell transcriptome-wide Mendelian randomization (scTWMR) and Bayesian colocalization.
• Conducted functional analyses including enrichment, protein-protein interaction, and druggability assessment.

Main Results:

• Identified six significant gene-cell associations in CD4+ T cells, immature B cells, and plasma cells.
• Found strong colocalization evidence for PTCH1, MTHFD1L, and RP11-293M10.2.
• Enrichment analyses implicated Hedgehog signaling and folate metabolism pathways.

Conclusions:

• Established a genetically predicted causal link between immune cell-specific gene expression and MDD.
• PTCH1 and MTHFD1L are validated as potential drug targets for MDD.
• The study provides a framework for discovering and validating gene targets for precision immunotherapy.