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

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.