Abnormalities in the distribution of laminin and collagen type IV in Hirschsprung's disease

In vitro neurite outgrowth and neuronal survival are promoted by laminin, and neuronal migration is promoted by collagen type IV. This led to the hypothesis that Hirschsprung's disease (HD) could be the result of an abnormal extracellular matrix microenvironment in the affected bowel during embryogenesis. Using indirect immunohistochemistry, we studied the distribution of laminin and collagen type IV in the bowel specimens of eight HD patients (four neonates and four infants) and 16 age- and site-matched controls from non-HD patients. In eight HD specimens, the tissue studied was from the aganglionic, transitional, and proximal normoganglionic zones. Uniform distribution of laminin and collagen type IV was observed in the basement membranes of all control specimens. The semiquantitative abnormality in the distribution of these proteins in HD occurred as follows: immunoreactivities were more intense in the inner circular layer, diminishing with a gradient in the outer muscularis externa in six of six aganglionic, four of five transitional, and three of eight normoganglionic sections. The qualitative abnormality of these proteins in HD was speckled immunofluorescence outside the basement membranes of the muscularis externa in all three zones of neonatal specimens only. These findings support the microenvironment hypothesis of the pathogenesis of HD.