Tissue-embedded CD4⁺ plasticity defines mucosal immunity in inflammatory bowel disease

Area of Science:

• Immunology
• Gastroenterology
• Cell Biology

Background:

• CD4⁺ T helper (Th) cell responses to gut microbiota are implicated in Inflammatory Bowel Disease (IBD).
• The coexistence and evolution of Th cell programs within human tissues in IBD remain unclear.

Purpose of the Study:

• To profile CD4⁺ memory T cells in intestinal biopsies to map phenotypes, functional states, and spatial relationships in IBD.
• To elucidate the plasticity and differentiation pathways of Th cells in the inflamed intestinal microenvironment.

Main Methods:

• Immunological and histological profiling of CD4⁺ memory T cells from intestinal biopsies.
• Analysis of cell phenotypes, functional states, and spatial distribution using techniques like trajectory visualization and correlation network analysis.
• T-cell receptor (TCR) stimulation assays during active disease to assess cytokine production.

Main Results:

• Expansion of CD4⁺ T cells and RORγt⁺ Th cells with elevated T-bet expression correlated with IBD progression.
• Emergence of Foxp3⁺ cells co-expressing RORγt indicated regulatory-Th17 plasticity, with potential differentiation towards regulatory or Th17-like fates.
• Pro-inflammatory CD4⁺ states were linked to cytotoxic CD8⁺ subsets, and distinct spatial segregation of tissue-resident CD4⁺ and CD8⁺ T cells was observed.

Conclusions:

• A dynamic, tissue-embedded CD4 T-cell landscape exists in IBD, characterized by Th cell plasticity and coordinated helper-cytotoxic lineage responses.
• Understanding these evolving Th cell programs is critical for deciphering IBD pathogenesis and developing targeted therapies.