Reduced expression of the NLRP6 inflammasome in the colon of patients with Hirschsprung's disease.

Purpose: Hirschsprung's associated enterocolitis (HAEC) is the most common cause of morbidity and mortality in Hirschsprung's Disease (HSCR). The pathogenesis of HAEC remains unsatisfactorily understood. Mounting evidence of an altered microbiome in patients with HSCR adds a new angle to the pathogenesis of HAEC. NLRP6 is a member of the nucleotide-binding domain, leucine-rich-repeat-containing (NLR) innate immune receptor family, a multiprotein complex that functions as a sensor of damage-associated molecular patterns. Known as inflammasomes they have been implicated in the regulation of colonic microbial ecology and by alteration, regulators of inflammation. We designed this study to test the hypothesis that NLRP6 expression is altered in the colon of patients with HSCR.

Methods: We investigated NLPR6 protein expression in both the aganglionic and ganglionic regions of HSCR patients (n = 10) versus healthy control colon (n = 10). Protein distribution was assessed by using immunofluorescence and confocal microscopy. Gene and protein expressions were quantified using quantitative real-time polymerase chain reaction (qPCR), Western blot analysis, and densitometry.

Main Results: qPCR and Western blot analysis revealed that NLRP6 is expressed in the colon of patients with HSCR. NLRP6 expression was significantly decreased (p < 0.003) in the ganglionic and aganglionic bowel in HSCR compared to controls. Confocal microscopy revealed that NLRP6 expression in colonic epithelium was markedly decreased in HSCR specimens compared to controls.

Conclusion: We demonstrate for the first time the expression and distribution of NLRP6 in patients with HSCR. The observed decreased expression of NLRP6 may contribute to an altered colonic microbiome in patients with HSCR and increases the susceptibility to develop HAEC.