Microscopic colitis patients demonstrate a mixed Th17/Tc17 and Th1/Tc1 mucosal cytokine profile

• We examine effector T cell subsets related cytokines in mucosa of MC patients.
• IFN-γ and IL-12 transcripts are elevated in both forms of microscopic colitis (MC).
• IL23/Th17 pathway transcripts are also elevated in MC patients.
• IFN-γ, IL-21 and IL-22 mRNA levels were associated with clinical activity in MC.
• MC patients demonstrate a mixed Th17/Tc17 and Th1/Tc1 mucosal cytokine profile.

BackgroundMicroscopic colitis (MC) is a chronic inflammatory bowel disorder of unknown aetiology comprising collagenous colitis (CC) and lymphocytic colitis (LC). Data on the local cytokine profile in MC is limited. This study investigated the T helper (Th) cell and cytotoxic T lymphocyte (CTL) mucosal cytokine profile at messenger and protein levels in MC patients.MethodsMucosal biopsies from CC (n = 10), LC (n = 5), and CC or LC patients in histopathological remission (CC-HR, n = 4), (LC-HR, n = 6), ulcerative colitis (UC, n = 3) and controls (n = 10) were analysed by real-time PCR and Luminex for expression/production of IL-1β, -4, -5, -6, -10, -12, -17, -21, -22, -23, IFN-γ, TNF-α, T-bet and RORC2.ResultsMucosal mRNA but not protein levels of IFN-γ and IL-12 were significantly up regulated in CC, LC as well as UC patients compared to controls. Transcription of the Th1 transcription factor T-bet was significantly enhanced in CC but not LC patients. mRNA levels for IL-17A, IL-21, IL-22 and IL-6 were significantly up regulated in CC and LC patients compared to controls, albeit less than in UC patients. Significantly enhanced IL-21 protein levels were noted in both CC and LC patients. IL-6 protein and IL-1β mRNA levels were increased in CC and UC but not LC patients. Increased mucosal mRNA levels of IFN-γ, IL-21 and IL-22 were correlated with higher clinical activity, recorded as the number of bowel movements per day, in MC patients.Although at lower magnitude, IL-23A mRNA was upregulated in CC and LC, whereas TNF-α protein was increased in CC, LC as well as in UC patients.Neither mRNA nor protein levels of IL-4, IL-5 or IL-10 were significantly changed in any of the colitis groups. LC-HR and especially CC-HR patients had normalized mRNA and protein levels of the above cytokines compared to LC and CC patients. No significant differences were found between LC and CC in cytokine expression/production.ConclusionLC and CC patients demonstrate a mixed Th17/Tc17 and Th1/Tc1 mucosal cytokine profile.