TRAV26-2 T-Cell Receptor Expression Is Associated With Mucosal Lymphocyte Response to Wheat Proteins in Patients With Functional Dyspepsia.

INTRODUCTION: An association between functional dyspepsia (FD) and wheat-containing foods has been reported in observational studies; however, an adaptive response has not been demonstrated. We examined whether antigens present in wheat could provoke a response from FD duodenal lymphocytes. METHODS: Lamina propria mononuclear cells (LPMCs) were isolated from duodenal biopsies from 50 patients with FD and 23 controls. LPMCs were exposed to gluten (0.2 mg/mL) or gliadin (0.2 mg/mL) for 24 hours. Flow cytometry was performed to phenotype lymphocytes. Quantitative PCR was used to measure the expression of gliadin-associated T-cell receptor alpha variant ( TRAV ) 26-2. RESULTS: In response to gliadin (but not gluten) stimulation, the effector Th2-like population was increased in FD LPMCs compared with that in controls and unstimulated FD LPMCs. Duodenal gene expression of TRAV26- 2 was decreased in patients with FD compared with that in controls. We identified a positive association between gene expression of this T-cell receptor variant and LPMC effector Th17-like cell populations in patients with FD, but not controls after exposure to gluten, but not gliadin. DISCUSSION: Our findings suggest that gliadin exposure provokes a duodenal effector Th2-like response in patients with FD, supporting the notion that food antigens drive responses in some patients. Furthermore, these findings suggest that altered lymphocyte responses to wheat proteins play a role in FD pathogenesis.

Increased mucosal eosinophils in colonic diverticulosis and diverticular disease.

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.

Does the microbiome play a role in the pathogenesis of colonic diverticular disease? A systematic review.

BACKGROUND AND AIMS: The role of the microbiota in diverticulosis and diverticular disease is underexplored. This systematic review aimed to assess all literature pertaining to the microbiota and metabolome associations in asymptomatic diverticulosis, symptomatic uncomplicated diverticular disease (SUDD), and diverticulitis pathophysiology. METHODS: Seven databases were searched for relevant studies published up to September 28, 2022. Data were screened in Covidence and extracted to Excel. Critical appraisal was undertaken using the Newcastle Ottawa Scale for case/control studies. RESULTS: Of the 413 papers screened by title and abstract, 48 full-text papers were reviewed in detail with 12 studies meeting the inclusion criteria. Overall, alpha and beta diversity were unchanged in diverticulosis; however, significant changes in alpha diversity were evident in diverticulitis. A similar Bacteroidetes to Firmicutes ratio compared with controls was reported across studies. The genus-level comparisons showed no relationship with diverticular disease. Butyrate-producing microbial species were decreased in abundance, suggesting a possible contribution to the pathogenesis of diverticular disease. Comamonas species was significantly increased in asymptomatic diverticulosis patients who later developed diverticulitis. Metabolome analysis reported significant differences in diverticulosis and SUDD, with upregulated uracil being the most consistent outcome in both. No significant differences were reported in the mycobiome. CONCLUSION: Overall, there is no convincing evidence of microbial dysbiosis in colonic diverticula to suggest that the microbiota contributes to the pathogenesis of asymptomatic diverticulosis, SUDD, or diverticular disease. Future research investigating microbiota involvement in colonic diverticula should consider an investigation of mucosa-associated microbial changes within the colonic diverticulum itself.

Mortality risk increased in colonic diverticular disease: a nationwide cohort study.

INTRODUCTION: There are limited population cohort data on overall and cause-specific mortality in colonic diverticular disease. OBJECTIVE: To measure overall and cause-specific mortality in colonic diverticular disease, compared to matched reference individuals and siblings. METHODS: Population-based cohort study ("the ESPRESSO study") in Sweden. There were 97,850 cases with a medical diagnosis of diverticular disease (defined by international classification of disease codes) and colorectal histology identified in 1987-2017 from histopathology reports. The mortality risk between individuals with colonic diverticular disease and matched reference individuals (n = 453/634) from the general population was determined. Cox regression models adjusted for comorbidity estimated hazard ratios (HRs) for all-cause mortality. RESULTS: During follow-up, there were 32,959 deaths in individuals with colonic diverticular disease (44/1000 person-years) compared with 127,153 in matched reference individuals (34/1000 person-years), resulting in an HR of 1.27 (95%CI 1.25-1.29). Also compared to siblings, colonic diverticular disease patients were at increased risk of death, HR 1.39 (95%CI 1.33-1.45). Mortality risks were further increased in colonic diverticular disease patients with a colorectal biopsy showing any mucosal inflammation HR 1.36; (95%CI 1.33-1.38), with the most significant increase during the first year after diagnosis HR 2.18; (95%CI 2.05-2.32). CONCLUSIONS: Mortality in colonic diverticular disease is increased over reference individuals in the general population. The presence of mucosal inflammation on colorectal biopsies is a predictor of increased risk of mortality.

Type 2 and type 17 effector cells are increased in the duodenal mucosa but not peripheral blood of patients with functional dyspepsia.

Background: Functional dyspepsia is characterised by chronic symptoms of post-prandial distress or epigastric pain not associated with defined structural pathology. Increased peripheral gut-homing T cells have been previously identified in patients. To date, it is unknown if these T cells were antigen-experienced, or if a specific phenotype was associated with FD. Objective: This study aimed to characterise T cell populations in the blood and duodenal mucosa of FD patients that may be implicated in disease pathophysiology. Methods: We identified duodenal T cell populations from 23 controls and 49 Rome III FD patients by flow cytometry using a surface marker antibody panel. We also analysed T cell populations in peripheral blood from 37 controls and 61 patients. Where available, we examined the number of duodenal eosinophils in patients and controls. Results: There was a shift in the duodenal T helper cell balance in FD patients compared to controls. For example, patients had increased duodenal mucosal Th2 populations in the effector (13.03 ± 16.11, 19.84 ± 15.51, p=0.038), central memory (23.75 ± 18.97, 37.52 ± 17.51, p=0.007) and effector memory (9.80±10.50 vs 20.53±14.15, p=0.001) populations. Th17 populations were also increased in the effector (31.74±24.73 vs 45.57±23.75, p=0.03) and effector memory (11.95±8.42 vs 18.44±15.63, p=0.027) subsets. Peripheral T cell populations were unchanged between FD and control. Conclusion: Our findings identify an association between lymphocyte populations and FD, specifically a Th2 and Th17 signature in the duodenal mucosa. The presence of effector and memory cells suggest that the microinflammation in FD is antigen driven.

Duodenal Pathology in Patients with Rumination Syndrome: Duodenal Eosinophilia and Increased Intraepithelial Lymphocytes.

BACKGROUND: Rumination syndrome is a functional gastrointestinal disorder characterized by effortless, postprandial regurgitation. Duodenal eosinophilia has been described in patients with functional dyspepsia. Because of the significant symptomatic overlap between functional dyspepsia and rumination syndrome, we hypothesized that histological changes might exist among patients with rumination syndrome. METHODS: We included patients with rumination syndrome in whom we had obtained duodenal biopsies and compared these with controls. Digital images of biopsy specimens were analyzed for routine pathology and eosinophil counts by a pathologist blinded to the case-control status. RESULTS: The 22 patients with rumination syndrome had a mean age of 39.2 years (range 21-71) and 77% were female. The 10 controls had a mean age of 34.3 (range 27-69) and 80% were female. There was a significant increase in the mean eosinophil count among the patients with rumination syndrome compared to controls, 26 per mm2 (range 16-42) versus 18 per mm2 (range 10-28), p = 0.006. Intraepithelial lymphocyte counts were significantly higher in rumination patients (mean 15/100 enterocytes, range 8-29) versus controls (mean 11/100 enterocytes, range 11-18), p = 0.02. CONCLUSION: Patients with rumination syndrome have subtle duodenal pathology with eosinophilia and increased intraepithelial lymphocyte counts compared to controls.