Down-regulation of Laminin and its Correlated Significance to Interstitial Cells of Cajal in Hirschsprung's Disease.

Introduction: Hirschsprung's Disease (HSCR) is characterized by aganglionosis in the distal gut, but the role of Extracellular Matrix (ECM) components in its pathogenesis remains unclear. This study investigated the relationship between laminin, a key ECM protein, and Interstitial Cells of Cajal (ICC) in HSCR.

Methods: Immunofluorescence staining was used to analyze the expression and localization of laminin and ICC in paraffin-embedded colon sections from HSCR patients. Whole-mount preparations and confocal microscopy were employed to visualize the ICC network. Laminin and c-Kit expression levels were evaluated by Western blot and qPCR. Isolated ICCs were treated with laminin-targeting siRNA or exogenous laminin protein. The effects on c-Kit expression, cell viability, and apoptosis were assessed via Western blot, qRT-PCR, MTT assay, and TUNEL staining.

Results: Laminin and ICCs were localized in the muscle layers and intermuscular regions, with laminin partially colocalizing with ICCs. In HSCR colon segments, laminin and ICC expression were significantly reduced, and ICC networks were disrupted (p < 0.05). Silencing laminin decreased c- Kit expression, ICC viability, and increased apoptosis, whereas exogenous laminin restored c-Kit expression, enhanced viability, and reduced apoptosis (p < 0.05).

Discussion: Our findings suggest laminin deficiency contributes to ICC loss in HSCR, impairing intestinal motility. This aligns with prior ECM-neural crest cell studies but contrasts with reports of elevated laminin in whole-tissue analyses, possibly due to regional or temporal differences. Limitations include reliance on rodent ICC models.

Conclusion: Laminin supports ICC viability and prevents apoptosis. Reduced laminin expression in HSCR contributes to the loss of ICC, disrupting pacemaker activity and impairing colonic motility.