Stem cell mobilization with G-CSF induces type 17 differentiation and promotes scleroderma

Area of Science:

• Immunology
• Hematology
• Transplantation Biology

Background:

• Allogeneic stem cell transplantation using G-CSF mobilized stem cells is linked to increased chronic graft-versus-host disease (GVHD).
• The underlying mechanisms driving this increased GVHD, particularly sclerodermatous GVHD, remain incompletely understood.

Purpose of the Study:

• To elucidate the mechanisms by which G-CSF mobilization influences T cell differentiation and contributes to chronic GVHD.
• To identify key molecular pathways and cellular players involved in G-CSF-induced sclerodermatous GVHD.

Main Methods:

• Analysis of T cell differentiation patterns following G-CSF mobilization.
• Investigation of the role of interleukin-21 (IL-21) signaling in G-CSF-induced T cell responses.
• Assessment of the contribution of interleukin-17A (IL-17A) and macrophages to skin fibrosis in a GVHD model.

Main Results:

• G-CSF promotes type 17 T cell differentiation, distinct from type 1 or type 2.
• G-CSF-induced IL-17 production in CD4+ and CD8+ T cells is mediated by IL-21 signaling.
• Donor-derived IL-17A drives macrophage infiltration and cutaneous fibrosis, manifesting as scleroderma, with CD8+ T cells being a primary source.

Conclusions:

• G-CSF-induced IL-17A production by T cells is a key driver of sclerodermatous chronic GVHD.
• Donor CD8+ T cells play a significant role in mediating IL-17A-dependent scleroderma.
• Targeting the IL-17A pathway presents a potential therapeutic strategy for preventing or treating G-CSF-associated sclerodermatous GVHD.