Colorectal mucus non‐invasively collected from patients with inflammatory bowel disease and its suitability for diagnostic cytology

Abstract

Colorectal mucus is a key component of the protective gut barrier which is altered in inflammatory bowel disease (IBD). We aimed to cytologically characterize colorectal mucus non-invasively collected from IBD patients using our new sampling technique. Colorectal mucus was self-collected by 58 IBD patients comprising 31 ulcerative colitis (UC) and 27 Crohn's disease (CD) cases. The samples were examined cytologically, and immunocytochemically. Large numbers of well-preserved granulocytes were typically detected (neutrophils undergoing degradation were observed as well). Plasma cells and erythrophagocytosis were present in 18.2% and 29.1% of cases, respectively, predominantly in patients with UC and distal CD. Immunocytochemical visualization of calprotectin in neutrophils, eosinophil-derived neurotoxin in eosinophils and tumour necrosis factor-α in macrophages was also achieved. Correct cytological diagnosis was made in 61.8% of analysed IBD cases. Our new method of colorectal mucus sampling provides highly informative material for cytology. Findings of the presence of plasmocytes and erythrophagocytosis in colorectal mucus are unique and may reflect previously unknown mechanisms of IBD pathogenesis. Immunocytochemical detection of inflammation biomarkers demonstrates the suitability of this material for biomarker quantification. These promising results suggest a potential role for colorectal mucus cytology in the non-invasive diagnosis of IBD.

Inflammatory bowel disease detection and monitoring by measuring biomarkers in non‐invasively collected colorectal mucus

“…21 Moreover, obtained samples had low fecal contamination, 21 were abundant in mucin 2 21 , and suitable for cytology. 22 The present paper demonstrates an impressive diagnostic performance of calprotectin and EDN, proving that non-invasively sampled colorectal mucus can be successfully used for both IBD detection and monitoring of anti-inflammatory therapy.…”

“…Eosinophil‐derived neurotoxin is a major secretory protein of the eosinophils . These granulocytes are readily detectable throughout the human gut in normal conditions, and their numbers are increased in both colorectal mucosa and colorectal mucus of IBD patients. Our observation of EDN abundance in the latter material confirms eosinophil participation in the inflammatory process, which involves both the mucosa and the protective mucus barrier overlaying it.…”

“…The impressive cytological findings from Stage 1 of this study were presented in our previous papers. 21,22 Briefly, the abundance of inflammatory cells was observed in most IBD cases, whereas none or very few cells were found in inflammation-free individuals. Inflammatory cell presence was clearly associated with calprotectin and EDN concentrations.…”

Characterization of colorectal mucus using infrared spectroscopy: a potential target for bowel cancer screening and diagnosis

“…Based on this concept and with the main goal of moving towards a 'liquid biopsy' approach, it is also crucial to study fresh mucus collected from patients. For this, a potential way forward could be to collect mucus as part of the FOBT screening [38,39].…”

Proteomics and Lipidomics in Inflammatory Bowel Disease Research: From Mechanistic Insights to Biomarker Identification

“…Finally, colorectal mucus could be further explored as a potential sample source. Previous studies have established that colorectal mucus is a rich source of potential IBD biomarkers, as demonstrated by the quantification of calprotectin and eosinophil-derived neurotoxin in mucus samples from IBD patients [ 110 , 111 ].…”