Increased mucosal eosinophils in colonic diverticulosis and diverticular disease

Abstract

Aims: Eosinophils contribute to tissue homeostasis, damage, and repair. The mucosa of colonic diverticula has not been evaluated for eosinophils by quantitative histology. We aimed to investigate whether mucosal eosinophils and other immune cells are increased in colonic diverticula.

Methods: Hematoxylin and eosin stained sections from colonic surgical resections (n = 82) containing diverticula were examined. Eosinophils, neutrophils, and lymphocytes, in five high power fields in the lamina propria were counted at the base, neck, and ostia of the diverticulum and counts compared to non-diverticula mucosa. The cohort was further subgrouped by elective and emergency surgical indications.

Results: Following an initial review of 10 surgical resections from patients with diverticulosis, a total of 82 patients with colonic resections containing diverticula from the descending colon were evaluated (median age 71.5, 42 M/40F). Eosinophil counts for the entire cohort were increased in the base and neck (median 99 and 42, both P = <0.001) compared with the control location (median 16). Eosinophil counts remained significantly increased in the diverticula base (both P = <0.001) and neck (P = 0.01 and <0.001, respectively) in both elective and emergency cases. Lymphocytes were also significantly increased at the diverticula base compared to controls in both elective and emergency subgroups.

Conclusion: Eosinophils are significantly and most strikingly increased within the diverticulum in resected colonic diverticula. While these observations are novel, the role of eosinophil and chronic inflammation is as yet unclear in the pathophysiology of colonic diverticulosis and diverticular disease.

Keywords: Anatomical histopathology; Diverticular disease; Diverticulitis; Diverticulosis; Eosinophil; Epidemiology; Gastroenterology; Inflammation.

Figure 1

Histopathology: colonic diverticulum with eosinophils indicated by blue arrows. Diverticulum observed digitally. H&E resection tissue from the sigmoid colon. (a) 0.5× magnification of diverticulum diagnosed as diverticulosis. (b) 40× magnification showing eosinophils in the base of lamina propria at the base of the diverticulum bulb.

Figure 2

Graphical image of a diverticulum showing regions at which cell counts were performed. 5HPF (high power fields) eosinophil (eos) counts were obtained at the base, neck, ostia, and control (non‐diverticula mucosal tissue). Image by BioRENDER.com.

Figure 3

Eosinophil counts as a whole cohort (n = 82). Box and violin plot showing the count sites: base, neck, and ostia, against the control site. Count numbers are indicated as numbers per 5HPFs. Pairwise comparisons with P‐value indicated. Median with 95% CI.

Figure 4

Neutrophil and lymphocyte cell counts in the study (n = 82). Box and violin plot showing (a) neutrophil and (b) lymphocyte counts performed at the diverticulum site: base, neck, and ostia against the control site. Count numbers are indicated as number per 5HPFs. Pairwise comparisons with P‐value indicated. Median with 95% CI.

Figure 5

Eosinophil counts for subgroups elective and emergency DD. Box and violin plot showing cell counts performed per site: base, neck, ostia against control for patients with diverticula at colonic resection for the subgroups (a) elective (n = 37) and (b) emergency (n = 45). Count numbers are indicated as numbers per 5HPFs. Pairwise comparisons with P‐value indicated. Median with 95% CI.

Figure 6

Neutrophil, and lymphocyte cell counts in subgroups elective (n = 37) and emergency (n = 45). Box and violin plot showing (a,b) for neutrophil cell counts and (c,d) for lymphocyte cell counts, for sites: base, neck, and ostia, against control site. Count numbers are indicated as numbers per 5HPFs. Top row (left to right) shows elective subgroup, and bottom row (left to right) shows emergency subgroup. Pairwise comparisons with P‐value indicated. Median with 95% CI.