T lymphocyte activation in visceral adipose tissue of patients with oesophageal adenocarcinoma

BACKGROUND: Visceral adipose tissue may fuel obesity-associated chronic inflammation and tumorigenesis. T cells may be important in visceral adipose tissue in driving inflammation, but they have not yet been characterized in patients with cancer. This study aimed to characterize T lymphocytes in visceral adipose tissue and peripheral blood from patients with oesophageal adenocarcinoma.

METHODS: Omental fat was taken from 35 patients with oesophageal adenocarcinoma at the start of surgery. Flow cytometry was performed to assess T cell activation status and cytokine production in omentum and peripheral blood.

RESULTS: A large population of lymphocytes was present in the omentum. Omental CD4(+) and CD8(+) T cells displayed significantly enhanced expression of the T cell activation markers CD69 (P < 0·001) and CD107a (CD8(+) T cells: P < 0·01), and significantly decreased CD62L expression (P < 0·05), compared with blood. Significantly higher proportions of CD45RO(+) T cells compared with CD45RA(+) T cells were present in omentum (P < 0·001 and P = 0·012 for CD4(+) and CD8(+) cells respectively). Interferon γ was the most abundant cytokine expressed by omental T cells, with a significantly higher level than in blood and subcutaneous adipose tissue (P < 0·01).

CONCLUSION: Visceral adipose tissue is a rich source of activated proinflammatory CD4(+) and CD8(+) T cells. It may fuel chronic inflammation via T cell-mediated pathways.