A comparison between colonic submucosa and mucosa to detect Lewy pathology in Parkinson's disease

Lewy bodies and neurites (LN), the two pathological hallmarks of Parkinson's disease (PD), are found in the enteric nervous system (ENS). Previously, we have shown that whole mounts of submucosa obtained after microdissection of colonic biopsies can be used for the detection of LN in the submucosal plexus (SMP) of PD patients. Recent reports suggest that Lewy pathology may extend beyond the submucosa to involve the digestive mucosa. The aim of the present research was to determine whether the analysis of the mucosa obtained after microdissection may help improve the sensitivity of colonic biopsies to detect Lewy pathology in the colon of PD patients.

Nine PD patients and 10 controls were included. Four biopsies were taken from the sigmoid/descending colon junction during the course of a rectosigmoidoscopy (short colonoscopy) in PD patients and during a total colonoscopy for colorectal screening in controls. Biopsies were microdissected, the mucosa was separated from the submucosa and both structures were analyzed by immunohistochemistry. Immunohistochemical analysis was performed using antibodies against phosphorylated alpha-synuclein to detect LN and neurofilaments NF200 kDa to label the neuronal structures.

Lewy neurites were present in the SMP of four patients and in the mucosa of three patients. Remarkably, among the patients who displayed LN within their mucosa, one was devoid of Lewy pathology in his SMP. No LN were observed in the mucosa and the SMP of controls.

The parallel analysis of colonic mucosa, along with the SMP, can help detect Lewy pathology in PD.