--Paneth cell niche function is critical for intestinal stem cells in radiation injury but dispensable in GVHD.

Paneth cell niche function is essential for intestinal regeneration after radiation injury but not necessary in graft-versus-host disease.

• Why it matters: Understanding the specific roles of Paneth cells in intestinal health is crucial because their contributions to stem cell support may influence treatment strategies for radiation damage and GVHD, yet their exact functions remain unclear.
• What they did: Using Lysozyme1-DTR mice to ablate Paneth cells, the study examined WNT3 and EGF expression, intestinal injury responses, and the impact on stem cell regeneration in radiation and GVHD models, including analysis of human biopsies.
• The result: Findings show Paneth cells provide critical EGF support for radiation-induced intestinal repair, but their role is redundant during GVHD, suggesting injury severity rather than Paneth cell loss drives observed changes.