Inhibition of TGF-β Signaling by IL-15: A New Role for IL-15 in the Loss of Immune Homeostasis in Celiac Disease

Lack of induction of Smad7 and TGIF by IL-15 in control IEL and LPL. IEL and LPL isolated from controls were left unstimulated or cultured for 5 days with 10 ng/mL of IL-15. TGIF and Smad7 mRNA were quantified by real-time PCR. Results, expressed in arbitrary units, are from 3 independent experiments.

Phospho-c-jun up-regulation induced by IL-15 is not mediated by TNF-α secretion. Peripheral and intestinal T lymphocytes were cultured with medium added or not with IL-15 (10 ng/mL) and/or anti-TNF-α (10 μg/mL) for 5 days. (A) Histogram analysis of intracellular staining of phospho-c-jun in peripheral CD3+ lymphocytes on day 5. (B) Intracellular labeling for TNF-α was monitored every day by flow cytometry in peripheral CD3+ lymphocytes, IEL and LPL. Cells induced with PMA (50 ng/mL) and ionomycin (10−6 M) for 24 hours were used as positive controls. Results, obtained on day 1 and day 5 are shown. Results are representative of 2 independent experiments.