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

Background 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. Methods 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. Results 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-6R alpha were decreased in MC but increased in UC compared to controls. Conclusions 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.