IL-15 triggers an antiapoptotic pathway in human intraepithelial lymphocytes that is a potential new target in celiac disease–associated inflammation and lymphomagenesis
Georgia Malamut, Raja El Machhour, Nicolas Montcuquet, Séverine Martin-Lannerée, Isabelle Dusanter-Fourt, Virginie Verkarre, Jean-Jacques Mention, Gabriel Rahmi, Hiroshi Kiyono, Eric A. Butz, Nicole Brousse, Christophe Cellier, Nadine Cerf-Bensussan, Bertrand Meresse
Georgia Malamut, Raja El Machhour, Nicolas Montcuquet, Séverine Martin-Lannerée, Isabelle Dusanter-Fourt, Virginie Verkarre, Jean-Jacques Mention, Gabriel Rahmi, Hiroshi Kiyono, Eric A. Butz, Nicole Brousse, Christophe Cellier, Nadine Cerf-Bensussan, Bertrand Meresse
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Research Article Gastroenterology

IL-15 triggers an antiapoptotic pathway in human intraepithelial lymphocytes that is a potential new target in celiac disease–associated inflammation and lymphomagenesis

Abstract

Enteropathy-associated T cell lymphoma is a severe complication of celiac disease (CD). One mechanism suggested to underlie its development is chronic exposure of intraepithelial lymphocytes (IELs) to potent antiapoptotic signals initiated by IL-15, a cytokine overexpressed in the enterocytes of individuals with CD. However, the signaling pathway by which IL-15 transmits these antiapoptotic signals has not been firmly established. Here we show that the survival signals delivered by IL-15 to freshly isolated human IELs and to human IEL cell lines derived from CD patients with type II refractory CD (RCDII) — a clinicopathological entity considered an intermediary step between CD and enteropathy-associated T cell lymphoma — depend on the antiapoptotic factors Bcl-2 and/or Bcl-xL. The signals also required IL-15Rβ, Jak3, and STAT5, but were independent of PI3K, ERK, and STAT3. Consistent with these data, IELs from patients with active CD and RCDII contained increased amounts of Bcl-xL, phospho-Jak3, and phospho-STAT5. Furthermore, incubation of patient duodenal biopsies with a fully humanized human IL-15–specific Ab effectively blocked Jak3 and STAT5 phosphorylation. In addition, treatment with this Ab induced IEL apoptosis and wiped out the massive IEL accumulation in mice overexpressing human IL-15 in their gut epithelium. Together, our results delineate the IL-15–driven survival pathway in human IELs and demonstrate that IL-15 and its downstream effectors are meaningful therapeutic targets in RCDII.

Authors

Georgia Malamut, Raja El Machhour, Nicolas Montcuquet, Séverine Martin-Lannerée, Isabelle Dusanter-Fourt, Virginie Verkarre, Jean-Jacques Mention, Gabriel Rahmi, Hiroshi Kiyono, Eric A. Butz, Nicole Brousse, Christophe Cellier, Nadine Cerf-Bensussan, Bertrand Meresse

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Figure 3

The Jak3/STAT5 signaling pathway is essential for IL-15–mediated survival of RCDII IEL lines.

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The Jak3/STAT5 signaling pathway is essential for IL-15–mediated surviva...
(A) Quantification of apoptosis in 5 RCDII IEL lines cultured for 72 hours with IL-15 in the presence of kinase inhibitors. Percentages of apoptotic cells, determined by flow cytometry as in Figure 2A, increased significantly after treatment with the Jak3 inhibitor WHIP-131 (JAK3i) and IL-15 starvation (0), but not with AG490, the PI3K inhibitors LY294002 and wortmannin, or the ERK inhibitor U0126 (ERKi). *P < 0.001 versus IL-15 alone, 1-way ANOVA with Tukey’s multiple comparison test. (B) Flow cytometry indicated that WHIP-131, but not LY294002 (black histograms and text), reduced expression of Bcl-2 and Bcl-xL compared with control cells (gray filled histograms and text). (C) In contrast, proliferation of RCDII IEL lines to 10 ng/ml IL-15 assessed by 3H thymidine incorporation was inhibited by both LY294002 and WHIP-131. Shown is 1 representative experiment of 3. (D) WHIP-131 decreased expression of phospho-STAT5 and phospho-STAT3 in treated cells (black histograms and text) compared with untreated cells (gray filled histograms and text). (E and F) Specific inhibition of STAT5 and STAT3 expression by shRNA in 1 RCDII IEL line cultured in IL-15. shLuc, control shRNA directed against the luciferase protein. (E) Analysis of signaling molecules and caspase 3 activation by Western blot. (F) Cell survival, measured as the number of viable cells and the percentage of trypan blue–positive (i.e., dead) cells. Inhibition of STAT5, but not STAT3, reduced expression of Bcl-2 and Bcl-xL and induced caspase 3 activation and cell death. Dashed lines in B and D denote isotype controls.