Morphological, Molecular and Motility Changes in Human Small Intestine After Loop Ileostomy

Area of Science:

• Gastroenterology
• Surgical Physiology
• Molecular Biology

Background:

• Loop ileostomy surgery can lead to villous atrophy and reduced smooth muscle contractility.
• Understanding motility changes in proximal and distal ileostomy limbs is crucial for patient outcomes.

Purpose of the Study:

• To investigate the morphological, molecular, and functional changes in the motility of proximal and distal ileostomy limbs.
• To elucidate the underlying causes of altered smooth muscle contractility post-ileostomy.

Main Methods:

• Analysis of full-thickness circular muscle strips from 25 patients.
• Quantification of contractile protein expression using Western blot.
• Gene expression analysis via quantitative real-time polymerase chain reaction.

Main Results:

• The distal ileostomy limb exhibited morphological atrophy and reduced contractile responses to acetylcholine and potassium chloride.
• Significant down-regulation of key contractile proteins (myosin phosphatase targeting subunit 1, protein kinase C-potentiated phosphatase inhibitor protein-17 kDa, Rho-associated protein kinase 1) was observed in the distal limb.
• Numbers of platelet-derived growth factor receptor-α-positive (PDGFRα+) cells, interstitial cells of Cajal (ICC), and neuronal cells remained unchanged between proximal and distal limbs.

Conclusions:

• Despite morphological and molecular alterations, including contractile protein down-regulation in the distal ileostomy loop, essential cell populations (PDGFRα+, ICCs, neurons) are preserved.
• These findings may explain the successful restoration of bowel motility after ileostomy reversal and the low incidence of postoperative ileus.