Physiological and pathogenic T cell autoreactivity converge in type 1 diabetes

Area of Science:

• Immunology
• Endocrinology
• Autoimmunity Research

Background:

• Autoimmune diseases stem from autoantigen-driven adaptive immunity activation.
• Autoreactive T cells are present in healthy individuals, necessitating study of their dynamic changes in health and disease.
• Type 1 diabetes (T1D) serves as a key model for investigating physiological versus pathogenic autoreactive processes.

Purpose of the Study:

• To investigate the physiological and pathogenic roles of autoreactive T cells in Type 1 diabetes (T1D).
• To analyze the dynamics of T cell receptor (TCR) repertoires specific to the autoantigen glutamic acid decarboxylase 65 (GAD65) in T1D patients and healthy donors.

Main Methods:

• Employed single-cell gene expression profiling.
• Utilized tandem T cell receptor (TCR) sequencing.
• Analyzed phenotype and TCR repertoire of GAD65-specific T cells.

Main Results:

• GAD65-specific naive T cells are found in both healthy individuals and T1D patients.
• Ratios of GAD65-specific effector and memory T cell responses are similar between healthy donors and patients.
• Differential features in GAD65-specific TCRs were observed, including smaller clonal sizes of healthy donor-derived clonotypes in patients.

Conclusions:

• Proposes a model where physiological autoimmunity against GAD65 is crucial during early development.
• Suggests that dysregulation of these physiological autoimmune responses in susceptible individuals can lead to overt Type 1 diabetes.
• Highlights the importance of studying autoreactive T cell dynamics for understanding T1D pathogenesis.