Expanded CD4(+) Effector/Memory T Cell Subset in APECED Produces Predominantly Interferon Gamma

Area of Science:

• Immunology
• Genetics
• Human Pathology

Background:

• Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autoimmune disorder.
• It is caused by mutations in the AIRE gene, leading to impaired T cell populations.
• The role of CD4(+) T helper (Th) cells in APECED remains understudied.

Purpose of the Study:

• To elucidate the role of CD4(+) T helper cells in the pathogenesis of APECED.
• To investigate abnormalities in Th cell populations in APECED patients.

Main Methods:

• Analysis of ten APECED patients and ten healthy controls.
• Utilized cell culture assays, multiparameter flow cytometry, and transcriptome analysis.
• Explored CD4(+) T helper cell populations, including naive, effector/memory, and recent thymic emigrants (RTEs).

Main Results:

• Increased proportions of effector/memory Th cells and decreased naive Th cells observed.
• Naive Th cells showed abnormal activation with increased Th1, Th2, and Th17 cytokine expression.
• Transcriptome analysis indicated abnormalities in the Th1 interferon gamma (IFN-γ) pathway; IFN-γ showed the highest expression, potentially promoting CD8(+) cytotoxic cell function.
• Decreased frequency of CD4(+) RTEs in patients, with RTEs exhibiting increased cytokine production.

Conclusions:

• Abnormalities in the CD4(+) T helper cell population contribute to APECED pathogenesis.
• Evidence suggests premature activation of Th cells within the thymus may underlie these abnormalities.
• Findings highlight the importance of Th cells in understanding APECED.