# Increased Colonic Levels of CD8+ Cytotoxic T lymphocyte-Associated Mediators in Patients With Microscopic Colitis

## TL;DR

Patients with microscopic colitis show higher levels of immune-related molecules linked to CD8+ T cells, suggesting a different disease mechanism compared to ulcerative colitis.

## Contribution

The study identifies distinct immune mediator profiles in microscopic colitis compared to ulcerative colitis and controls.

## Key findings

- Granzyme B and CCL5 levels were higher in active collagenous colitis than in ulcerative colitis.
- Microscopic colitis showed increased levels of CD8+ T cell-associated mediators compared to controls.
- MMP-1 and MMP-3 levels were higher in collagenous colitis than in lymphocytic colitis.

## Abstract

For unidentified reasons, possibly due to increased immune surveillance, patients with collagenous colitis (CC) and lymphocytic colitis (LC), both forms of microscopic colitis (MC), have lower risk of colorectal cancer than controls and ulcerative colitis (UC) patients. Levels of secreted and cell-bound mediators in MC patients with active disease and in histological remission (HR) compared to UC patients and controls were investigated.

Median fluorescence intensity of 54 analytes in colonic biopsies from patients with active CC (n = 21), LC (n = 11), and UC (n = 19); CC-HR (n = 6), LC-HR (n = 9), UC in remission (n = 19), non-diarrhea controls (n = 48), and diarrhea controls (n = 25) was measured using Luminex.

Granzyme B and CCL5 levels were higher in active CC than in UC, whereas CCL4 and CD163 levels were similar in CC and UC, and both groups had higher levels of matrix metalloproteinase (MMP)-1, MMP-3, and tumor necrosis factor receptor II than both control groups. APRIL, BAFF, BCMA, CCL20, CXCL8, chitinase 3-like 1, pentraxin-3, Fas, and IL-33 were higher in UC than MC. Increases in 4-1BB and perforin in MC compared to controls were lower than in UC. Levels of gp130 and IL-6Rα were decreased in MC but increased in UC compared to controls.

Microscopic colitis patients exhibit increased levels of several analytes, including some associated with CD8+ T lymphocytes, suggesting a different pathogenesis of MC compared to UC. Higher levels of MMP-1 and MMP-3 in CC than LC indicate separate disease entities.

Graphical Abstract