# Perlecan, CollagenXVIII, and Agrin Expression in Normo‐, Hypo‐, and Aganglionic Segments in Hirschsprung's Disease

## TL;DR

This study investigates the expression of specific proteoglycans in the gut of Hirschsprung's disease patients and finds differences in aganglionic segments.

## Contribution

The study provides the first detailed description of HSPG expression patterns in human HSCR patients.

## Key findings

- Perlecan, COL18A1, and agrin are expressed in the periganglionic basement membrane of the human ENS.
- Expression patterns in normoganglionic and hypoganglionic HSCR tissues are similar to controls.
- In aganglionic segments, immunoreactivity of HSPGs is reduced or absent in the intermuscular layer.

## Abstract

Secretory heparan sulphate proteoglycans (HSPGs) interact with various morphogens, growth factors, and signaling molecules contributing to the development of the enteric nervous system (ENS). Thus, HSPGs have come into focus as pathomechanistic players of enteric neuropathies, such as Hirschsprung's disease (HSCR) in animal models. However, a detailed description of HSPG expression in human HSCR patients is missing.

We characterized the expression pattern of the secretory HSPGs perlecan, COL18A1, and agrin in the human ENS and investigated differences in affected and healthy intestinal segments. Thus, comparative immunostainings were performed on human gut samples from HSCR‐patients and on non‐HSCR controls as well as tissues from human body donors.

Strikingly, we found that perlecan, COL18A1, and agrin were expressed as periganglionic basement membrane‐like structures in the human ENS. Interestingly, the expression pattern in normoganglionic and hypoganglionic HSCR‐tissues was comparable to the expression pattern in control tissues, despite the loss of neuronal differentiation markers in hypoganglionic segments. In aganglionic segments, the immunoreactivity of the investigated secretory HSPGs in the intermuscular layer was markedly reduced or not detectable. Yet, they were still readily visible in the Tunica muscularis, around blood vessels, and in the epithelium, with an almost unaltered immunoreactive pattern compared to the ganglionic segment.

Our study transferred valuable findings on the role of HSPGs in ENS development gained in animal models to human HSCR patients. Beyond their implications for understanding enteric neuropathies, we discuss our findings in the context of how the extracellular matrix might regulate homeostasis and regeneration in the human ENS.

Perlecan, COL18A1, and agrin are expressed in the human ENS and are part of the basement membrane ensheathing enteric ganglia.Expression pattern of perlecan, COL18A1, and agrin is comparable in normoganglionic segments of Hirschsprung's disease and non‐Hirschsprung controls.ENS‐related secretory HSPGs vanish with enteric ganglia in the transition zone from hypoganglionic to aganglionic gut segments.

Perlecan, COL18A1, and agrin are expressed in the human ENS and are part of the basement membrane ensheathing enteric ganglia.

Expression pattern of perlecan, COL18A1, and agrin is comparable in normoganglionic segments of Hirschsprung's disease and non‐Hirschsprung controls.

ENS‐related secretory HSPGs vanish with enteric ganglia in the transition zone from hypoganglionic to aganglionic gut segments.

The secretory heparan sulphate proteoglycans perlecan, agrin, collagen18A1 are expressed in the periganglionic sheath of enteric ganglia in resectates of Hirschsprung's disease patients and non‐Hirschsprung controls.