Reduced T cell receptor excision circle (TREC) levels in the colonic mucosa of microscopic colitis patients indicate local proliferation rather than homing of peripheral lymphocytes to the inflamed mucosa

• Aims: Dysregulated T cell responses in the intestine may lead to chronic bowel inflammation such as collagenous colitis (CC) and lymphocytic colitis (LC), together known as microscopic colitis (MC). Having demonstrated increased local T cell responses in the intestinal mucosa of MC patients, we investigated the recent thymic emigrants by measuring T cell receptor excision circle (TREC) levels in the colonic mucosa of CC and LC patients.Methods: Mucosal biopsies from CC (n=8), LC (n=5), and CC or LC patients in histopathological remission, (CC-HR, n=3), (LC-HR, n=6), non-inflamed diarrhoea patients (n=17) and controls (n=10) were analysed for TRECs expression by real time PCR.Results: The median TREC levels were lower in both CC and LC patients as well as in LCHR patients compared to controls. In contrast to MC patients, non-inflamed diarrhoea patients presented with enhanced TREC levels compared to controls. None of the recorded differences did however reach statistical significance. No differences were observed in median TREC levels in either CC-HR or LC-HR patients compared to active CC and LC patients. A trend towards increased relative expression of CD3 was noted in all MC subgroups examined; and reached statistical significance in LC patients compared to controls. LC patients had ignificantly increased CD3 mRNA levels also compared to CC, CC-HR, LC-HR and non-inflamed iarrhoea patients.Conclusions: Reduced TRECs level in the colonic mucosa, together with our previously demonstrated enhanced expression of Ki67+ T cells, suggest local expansion of resident T lymphocytes in the inflamed mucosa of MC patients.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinsk bioteknologi -- Biomedicinsk laboratorievetenskap/teknologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Medical Biotechnology -- Biomedical Laboratory Science/Technology (hsv//eng)

Nyckelord

Microscopic colitis

collagenous colitis

lymphocytic colitis

T cells

T cell receptor excision circles (TRECs)

Biomedicin

Biomedicine

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)