DIAPH1-Deficiency is Associated with Major T, NK and ILC Defects in Humans

Area of Science:

• Immunology
• Cell Biology
• Genetics

Background:

• Loss of function mutations in Diaphanous related formin 1 (DIAPH1) are linked to combined immunodeficiency.
• The specific impact of DIAPH1 mutations on T cells, NK cells, and ILCs remains largely unexplored.

Purpose of the Study:

• To characterize the functional defects in T cells, NK cells, and ILCs caused by DIAPH1 loss of function mutations.
• To investigate the role of DIAPH1 in immune cell development, signaling, and function.

Main Methods:

• Whole exome sequencing to identify DIAPH1 mutations.
• Flow cytometry, confocal microscopy, and qPCR to assess T and NK cell function.
• Mass spectrometry to analyze CD4+ T cell proteome.
• shRNA-mediated knockdown of DIAPH1 in Jurkat cells.

Main Results:

• DIAPH1 variants significantly reduced DIAPH1 mRNA and protein levels.
• DIAPH1-deficient T cells exhibited defects in proliferation, activation, TCR signaling, and IL-2/STAT5 axis.
• Impaired transwell migration and reduced Treg cell generation were observed.
• NK cells showed diminished cytotoxic activity and IL-2/STAT5 signaling.
• Reduced numbers of all helper ILC subsets were found in patients.

Conclusions:

• DIAPH1 deficiency leads to severe functional impairments in T cells, NK cells, and helper ILCs.
• These findings highlight the critical role of DIAPH1 in the biology and function of these key immune cell subsets.
• DIAPH1 mutations contribute to combined immunodeficiency through widespread immune cell defects.