The enteric microbiota regulates jejunal Paneth cell number and function without impacting intestinal stem cells

Area of Science:

• Gastroenterology and Microbiology
• Intestinal epithelial cell biology
• Host-microbe interactions

Background:

• Paneth cells (PCs) in the small intestine secrete antimicrobial peptides (AMPs) that modulate gut microbiota.
• The reciprocal influence of the enteric microbiota on PC function remains largely unknown.

Purpose of the Study:

• To investigate the impact of the enteric microbiota on PC biology in the mouse small intestine.
• To assess effects on epithelial proliferation, intestinal stem cell (ISC) numbers, and AMP production.

Main Methods:

• Comparison of jejunal PCs in germ-free (GF) versus conventionally raised (CR) mice.
• Evaluation of epithelial proliferation, ISC counts, and AMP expression (specifically Reg3γ).
• Analysis of CR versus GF enteroids cultured with bacterial ligands.

Main Results:

• PC numbers were significantly higher in CR mice compared to GF mice.
• No significant differences in ISC numbers or proliferation were observed between GF and CR mice.
• Reg3γ transcript expression was elevated in CR mice, but this effect was lost in cultured enteroids and not induced by bacterial ligands.

Conclusions:

• The enteric microbiota regulates PC numbers and induces Reg3γ expression, but potentially indirectly.
• The microbiota does not significantly influence jejunal ISC numbers or proliferation.
• Findings are crucial for researchers using germ-free models and enteroids to study PC and ISC biology.