Aquaporin-5 Expression Is Reduced in Lymphocytic Colitis

OBJECTIVE

Aquaporin-5 (AQP5) is a member of a family of water channel proteins involved in the bidirectional transfer of water across cell membranes. Lymphocytic colitis (LC) and collagenous colitis (CC) are clinically similar diseases characterized by chronic watery diarrhea in patients with usually unremarkable colonic mucosa on colonoscopy. The aim of this study was to determine whether AQP5 expression in colonic epithelium is altered in LC and CC.

METHODS

Sections of formalin-fixed and paraffin-embedded colorectal biopsies from three control patients (CTL), 8 patients with chronic non-bloody diarrhea with biopsies negative for active inflammation or significant distortion (CTL-D), 8 patients with LC, and 5 with CC were stained for AQP5 using immunohistochemistry. The staining intensity was scored as 3 (strong), 2 (intermediate), 1 (weak), or 0 (no staining). Statistical analysis was performed using Prism 7 Statistical Soft-ware.

RESULTS

AQP5 was strongly expressed (score 3) in the epithelial cells in all three CTL cases and all 8 CTL-D cases. In the 5 cases of CC, 3(60%) had score 3 and 2(40%) had score 2, but none had a score of 1 or 0. Of the 8 LC cases, 2(25%) had score 3, 3 had score 2(37.5%), and 3 had score 1(37.5%) (p=0.0031). In the three cases of LC with markedly reduced AQP5 (score 1), enteric steroid treatment did not lead to significant improvement in diarrhea.

CONCLUSIONS

Colorectal AQP5 expression is reduced in most cases of LC. Markedly reduced AQP5 expression in LC may identify a subset of patients with suboptimal response to enteric steroid treatment. Additional larger studies are needed to confirm these findings.This abstract was presented in part at Digestive Diseases Week in San Diego, CA, May 2019.

Evaluation of Melatonin Secretion and Metabolism Exponents in Patients with Ulcerative and Lymphocytic Colitis

Inflammatory bowel diseases, particularly ulcerative colitis (UC) and lymphocytic colitis (LC), affect many people. The role of melatonin in the pathogenesis of UC is precisely determined, whereas in LC it remains unknown. The aim of this study was to compare the expression of the melatonin-synthesizing enzymes tryptophan hydroxylase (TPH1), arylalkylamine-N-acetyltransferase (AANAT), and N-acetylserotonin methyltransferase (ASMT) in the colonic mucosa and urinary excretion of 6-sulfatoxymelatonin in patients with ulcerative and lymphocytic colitis. The study included 30 healthy subjects (group C), 30 patients with severe ulcerative colitis (group UC), and 30 patients with lymphocytic colitis (group LC). The diagnosis was based on endoscopic, histological, and laboratory examinations. Biopsy specimens were collected from right, transverse, and left parts of the colon. The levels of mRNA expression, TPH1, AANAT, and ASMT were estimated in the colonic mucosa with RT-PCR. The urine concentration of aMT6s was determined by the photometric method. The expression of TPH1, AANAT, and ASMT in colonic mucosa in UC and LC patients was significantly higher than in healthy subjects. Significant differences were found in the urinary aMT6s excretion: group C—13.4 ± 4.8 µg/24 h, group UC—7.8 ± 2.6 µg/24 h (p < 0.01), group LC—19.2 ± 6.1 µg/24 h (p < 0.01). Moreover, a negative correlation was found between fecal calprotectin and MT6s—in patients with UC − r = −0.888 and with LC − r = −0.658. These results indicate that patients with UC and those with LC may display high levels of melatonin-synthesizing enzymes in their colonic mucosa, which could possibly be related to increased melatonin synthesis as an adaptive antioxidant activity.

Enhanced levels of chemokines and their receptors in the colon of microscopic colitis patients indicate mixed immune cell recruitment

Microscopic colitis (MC), comprising collagenous colitis (CC) and lymphocytic colitis (LC), is a common cause of chronic diarrhea. Various immune cell infiltrations in the epithelium and lamina propria are seen in MC immunopathology. We compared gene and protein expressions of different immune cell attracting chemokines and their receptors in colon biopsies from MC patients in active disease or histopathological remission (CC/LC-HR) with controls, using qRT-PCR and Luminex, respectively. CC and LC patients with active disease demonstrated a mixed chemokine profile with significantly enhanced gene and/or protein expressions of the chemokines CCL2, CCL3, CCL4, CCL5, CCL7, CCL22, CXCL8, CXCL9, CXCL10, CXCL11, and CX3CL1 and the receptors CCR2, CCR3, CCR4, CXCR1, CXCR2, and CX3CR1. Enhanced chemokine/chemokine receptor gene and protein levels in LC-HR patients were similar to LC patients, whereas CC-HR patients demonstrated almost normalized levels. These findings expand the current understanding of the involvement of various immune cells in MC immunopathology and endorse chemokines as potential diagnostic markers as well as therapeutic candidates. Moreover, this study further supports the hypothesis that CC and LC are two different entities due to differences in their immunoregulatory responses.

Chromogranin A cell density as a diagnostic marker for lymphocytic colitis

BACKGROUND

Lymphocytic colitis (LC) can be mistakenly diagnosed as irritable bowel syndrome (IBS). In a previous study on IBS, some patients showed extremely high colonic chromogranin A cell density. Further examination of these patients showed that they suffered from LC.

AIMS

To investigate whether chromogranin A cell density is increased in LC patients and to examine the possibility of using this increase as a marker for the diagnosis of LC.

METHODS

Fifty-seven patients diagnosed with LC and 54 controls were included in the study. Biopsies from the right and left colon were obtained from both patients and controls, which were immunostained using the Avidin-biotin-complex method for chromogranin A, and cell density was quantified.

RESULTS

In both the right and left colon of patients with LC, the density of chromogranin A was significantly higher than in controls. This increase in chromogranin A cells occurs whether the number of these cells is expressed as number/mm(2) epithelium or as number/field. Chromogranin A cell density for the right and left colon expressed as number of cells/mm(2) epithelium or as cell number/field showed a high sensitivity and specificity as a diagnostic marker for LC.

CONCLUSIONS

Chromogranin A is a common marker for endocrine cells, and the present finding suggests that colonic hormones are involved in the pathophysiology of LC. The chromogranin cell density seems to be a good diagnostic marker with high sensitivity and specificity in both the right and left colon, thus sigmoidoscopy can be used in the diagnosis of LC using with this marker.