Tight Junction Defects in Aganglionic and Ganglionic Colon in Children With Hirschsprung Disease.

Intestinal epithelial barrier loss has been suggested as a pathogenic factor in Hirschsprung-associated enterocolitis and intestinal dysfunction in children with Hirschsprung disease (HD), but there is a paucity of comprehensive studies on the tight junction proteins that regulate paracellular permeability in this population. This case-control study aimed to determine if colonic epithelial tight junction protein expression is altered in children with HD. We use quantitative immunofluorescence microscopy to assess the expression of tight junction proteins (claudin-1, claudin-2, claudin-3, claudin-4, claudin-7, claudin-15, ZO-1, ZO-2, and occludin) in 29 children with HD who underwent surgical reconstruction and 16 controls who underwent transmural colorectal surgical resection for other etiologies between January 2015 and December 2021. We found that the expression of claudin-2, claudin-15, and occludin was reduced in both ganglionic and aganglionic colon specimens from children with HD compared with controls. Expression of other tight junction proteins did not differ between the groups. Together with previous studies, these data suggest that decreased expression of paracellular Na+ and water channel-forming claudin-2 and claudin-15 may limit luminal hydration, enhance fecal stasis, and promote dysbiosis. Conversely, occludin downregulation can not only increase paracellular macromolecular flux but also limit epithelial sensitivity to apoptotic stimuli. Together, these changes in expression of claudin-2 and claudin-15, as well as occludin, may promote intestinal dysfunction and contribute to Hirschsprung-associated enterocolitis pathogenesis following surgical reconstruction.