Intestinal barrier to large particulates in mice

Area of Science:

• Toxicology
• Immunology
• Gastroenterology

Background:

• The intestinal barrier's integrity is crucial for preventing pathogen and foreign particle entry.
• Previous studies suggested rapid systemic absorption of ingested particles, but this requires further investigation.

Purpose of the Study:

• To evaluate the intestinal barrier function and particle translocation after oral administration of synthetic particles.
• To determine the fate and distribution of 15.8- and 5.7-micron particles in mice.

Main Methods:

• Mice were orally administered synthetic spherical particles (15.8- and 5.7-micron) acutely and chronically.
• Particle distribution was assessed in blood, Peyer's patches, mesenteric lymph nodes, liver, spleen, and lungs.

Main Results:

• 15.8-micron particles did not accumulate in tested organs, contradicting prior reports of rapid blood appearance.
• 5.7-micron particles were detected in Peyer's patches, lymph nodes, and lungs after chronic administration.
• These smaller particles persisted in tissues for at least 77 days post-ingestion, with Peyer's patches identified as the primary uptake site.

Conclusions:

• Intestinal uptake of large particles (>5 micron) poses potential hazards, though penetration frequency remains uncertain.
• Peyer's patches appear to be the main site for intestinal particle absorption, with sequestration in macrophages and lymphatic transport rather than portal blood circulation.