Modelling IRF8 Deficient Human Hematopoiesis and Dendritic Cell Development with Engineered iPS Cells

Area of Science:

• Stem Cell Biology
• Immunology
• Hematopoiesis

Background:

• Human induced pluripotent stem (iPS) cells differentiate into all three germ layers, including hematopoietic stem cells.
• Interferon regulatory factor 8 (IRF8) is a key transcription factor in myeloid cell development, particularly for dendritic cells (DCs).
• IRF8 mutations cause severe immunodeficiencies in monocytes and DCs.

Purpose of the Study:

• To investigate the role of IRF8 in human hematopoiesis and immune cell differentiation.
• To generate and characterize IRF8 knockout (IRF8-/-) iPS and embryonic stem (ES) cells for studying IRF8 function.
• To model human immunodeficiencies related to IRF8 deficiency in vitro.

Main Methods:

• Generated IRF8-/- iPS and ES cells using CRISPR/Cas9n genome editing.
• Induced hematopoietic differentiation of engineered stem cells.
• Differentiated hematopoietic progenitors into specific DC subsets (cDC1, cDC2, pDC) and other myeloid lineages.

Main Results:

• IRF8 is dispensable for initial hematopoietic progenitor development from iPS/ES cells.
• IRF8 deficiency impaired the development of cross-presenting cDC1 and plasmacytoid pDC, but not classical cDC2.
• IRF8 knockout cells showed a bias towards granulocytes over monocytes and exhibited impaired DC function (MHC II expression, cytokine response, migration, antigen presentation).

Conclusions:

• Engineered human IRF8 knockout stem cells provide a valuable model for studying IRF8-related immunodeficiencies.
• IRF8 plays a critical, lineage-specific role in the development of certain human dendritic cell subsets.
• The study elucidates molecular mechanisms underlying IRF8-deficient DC pathophysiology and associated immunodeficiencies.