Fibroblast diversity within human gut-associated lymphoid tissues

Area of Science:

• Immunology
• Gastroenterology
• Cell Biology

Background:

• Human gut-associated lymphoid tissues (GALT) are crucial for intestinal adaptive immunity.
• Understanding the diversity and function of GALT fibroblasts (FB) is limited.
• Fibroblasts play key roles in tissue structure and immune cell regulation.

Purpose of the Study:

• To map the fibroblast landscape within human GALT, including Peyer's patches (PP), mucosal isolated lymphoid follicles (M-ILF), and submucosal ILF (SM-ILF).
• To identify specific markers and subsets of GALT fibroblasts.
• To investigate the functional differences between fibroblast populations in various GALT niches and their relevance in inflammatory diseases.

Main Methods:

• Single-cell RNA sequencing
• Flow cytometry
• Confocal laser microscopy
• Analysis of human GALT samples (PP, M-ILF, SM-ILF)

Main Results:

• CD24 identified as a marker distinguishing GALT fibroblasts from other intestinal fibroblasts.
• Distinct subsets of CD24+ fibroblasts were identified within specific GALT niches.
• Significant differences in composition and transcriptional profiles were observed between M-ILF and SM-ILF fibroblasts, with SM-ILF fibroblasts showing enhanced T cell support functions.
• Altered transcription profiles in Peyer's patch T zone reticular cells were noted in Crohn's disease.
• Fibroblast-like cells with GALT profiles were detected in other chronic inflammatory conditions.

Conclusions:

• This study provides a comprehensive map of the human GALT fibroblast landscape.
• Distinct fibroblast subsets reside in specific GALT niches, suggesting specialized roles.
• Fibroblast heterogeneity in GALT is crucial for immune regulation and may be altered in inflammatory diseases like Crohn's disease.