The Inflammatory-Immune Axis in Thyroid Disease: A Mendelian Randomization Study

Area of Science:

• Immunology
• Endocrinology
• Genetics

Background:

• Growing evidence links inflammatory proteins to thyroid diseases.
• The causal nature of this association and the role of immune cells as intermediaries are unclear.

Purpose of the Study:

• To investigate causal relationships between inflammatory proteins, immune cells, and thyroid diseases (Graves' disease, Hashimoto's thyroiditis, thyroid cancer).
• To explore the mediating role of immune cells in these associations.

Main Methods:

• Bidirectional two-sample Mendelian randomization (MR) analysis using genome-wide association studies (GWAS) data.
• Utilized inverse variance-weighted (IVW) as the primary MR method, with sensitivity analyses for pleiotropy and heterogeneity.
• Employed a two-step MR design to assess immune cell mediation and False Discovery Rate (FDR) correction for multiple testing.

Main Results:

• CCL19 showed a negative association with Graves' disease (GD), implying reduced GD risk with higher CCL19.
• CCL19 positively correlated with Forward Scatter Area (FSC-A) on CD4+ T cells, indicating larger cell size.
• Larger CD4+ T cells (higher FSC-A) were inversely associated with GD, suggesting a protective effect.

Conclusions:

• Established a causal link between circulating inflammatory proteins and immune cells in Graves' disease.
• Immune cells, specifically CD4+ T cells characterized by FSC-A, act as intermediaries between inflammatory proteins and GD risk.