Intestinal fibroblast heterogeneity - unifying RNA-seq studies and introducing consensus-driven nomenclature.

Area of Science:

• Gastroenterology
• Cell Biology
• Immunology

Background:

• The colonic mucosa relies on a fibroblast network for extracellular matrix (ECM) production, remodeling, and epithelial support.
• Fibroblast heterogeneity is recognized, but inconsistent nomenclature and lack of specific markers impede classification and functional understanding.

Purpose of the Study:

• To comprehensively characterize fibroblast diversity in the mouse colonic mucosa using single-cell RNA sequencing (scRNA-seq).
• To define the specialized functions and spatial organization of distinct fibroblast subpopulations.
• To propose a standardized nomenclature for intestinal fibroblasts to improve research communication.

Main Methods:

• Single-cell RNA sequencing (scRNA-seq) was employed to analyze fibroblast populations in mouse colonic mucosa.
• Spatial mapping techniques were used to determine the tissue localization of identified fibroblast subsets.
• Trajectory analysis was performed to infer fibroblast differentiation pathways.
• Cell cycle scoring assessed fibroblast proliferation status during homeostasis.

Main Results:

• Six distinct fibroblast subpopulations with unique molecular profiles and functions were identified.
• Specific fibroblast subsets were found to be responsible for ECM production/remodeling, contractility, and secretion of signaling molecules (cytokines).
• These cytokine-secreting fibroblasts play roles in epithelial differentiation and stem cell niche maintenance.
• Spatial mapping revealed organized distribution within the mucosa, and trajectory analysis suggested distinct developmental routes.
• Fibroblasts were confirmed to be largely non-proliferative in the homeostatic state.

Conclusions:

• This study provides a detailed molecular and functional classification of colonic fibroblasts.
• The proposed standardized nomenclature facilitates clearer communication regarding fibroblast diversity and function.
• Understanding fibroblast heterogeneity is crucial for elucidating their roles in maintaining gut homeostasis and in the pathogenesis of gastrointestinal diseases.