Volume 138, Issue 7, Pages 2378-2387 (June 2010) Interleukin-15 and Its Soluble Receptor Mediate the Response to Infliximab in Patients With Crohn's Disease  Gregory Bouchaud, Erwan Mortier, Mathurin Flamant, Isabelle Barbieux, Ariane Plet, Jean–Paul Galmiche, Yannick Jacques, Arnaud Bourreille  Gastroenterology  Volume 138, Issue 7, Pages 2378-2387 (June 2010) DOI: 10.1053/j.gastro.2010.02.044 Copyright © 2010 AGA Institute Terms and Conditions

Figure 1 Clinical and biological markers of activity. The CDAI scores were calculated before and after IFX in CD patients. Total TNFα and CRP levels were measured in the sera of 40 CD patients before and after 3 infusions of IFX and in 37 healthy controls. In responder patients, (A) CDAI scores, (C) TNF levels, and (E) CRP levels were significantly higher compared with controls and decreased after 3 infusions of IFX. In contrast, in nonresponder patients, (B) CDAI scores, (D) TNF levels, and (F) CRP levels, which were significantly higher before the treatment compared with controls, remained increased after the treatment. ***P < .001. Gastroenterology 2010 138, 2378-2387DOI: (10.1053/j.gastro.2010.02.044) Copyright © 2010 AGA Institute Terms and Conditions

Figure 2 Serum cytokine levels. Total IL-6 and IL-1β levels were measured in the sera of 40 CD patients before and after IFX and in 10 healthy controls. In responder patients, (A) IL-6 and (C) IL-1β levels were significantly higher compared with controls and decreased after 3 infusions of IFX. In contrast, in nonresponder patients, (B) IL-6 levels and (D) IL-1β levels, which were significantly higher before the treatment compared with controls, remained increased after the treatment. ** P < .01. ***P < .001. Gastroenterology 2010 138, 2378-2387DOI: (10.1053/j.gastro.2010.02.044) Copyright © 2010 AGA Institute Terms and Conditions

Figure 3 IL-15, sIL-15Rα, and IL-15/sIL-15Rα complex levels in the serum of CD patients before and after IFX. Before IFX, IL-15 levels were significantly higher than in healthy controls in responder patients. (A) In contrast, in nonresponder patients, IL-15 levels were comparable with those of controls. (B and C) sIL-15Rα and IL-15/sIL-15Rα complex levels in the serum of CD patients before IFX were significantly higher than in healthy controls in responder patients and comparable with those of the controls in nonresponder patients. Gastroenterology 2010 138, 2378-2387DOI: (10.1053/j.gastro.2010.02.044) Copyright © 2010 AGA Institute Terms and Conditions

Figure 4 During IFX treatment, IL-15 level (A) increased in responder patients but (D) remained stable in nonresponder patients. (B and C) sIL-15Rα and IL-15/sIL-15Rα complex levels increased significantly after 3 infusions of IFX in responder patients. (E and F) In contrast, in nonresponder patients, sIL-15Rα and complex levels were not modified after IFX. *P < .05. **P <.01. Gastroenterology 2010 138, 2378-2387DOI: (10.1053/j.gastro.2010.02.044) Copyright © 2010 AGA Institute Terms and Conditions

Figure 5 Cellular expression of ADAM17 (in green) in (A) healthy controls and on (B) colonic biopsy specimens obtained from CD patients before IFX. (A and B) The cellular expression of ADAM17 was higher in CD patients compared with healthy controls. Cellular expression of IL-15Rα (in red) in (C) healthy controls and on (D) colonic biopsy specimens obtained from CD patients before IFX. (C and D) The cellular expression of IL-15Rα was higher in CD patients compared with healthy controls. IL-15Rα also is co-localized with cytokeratin in (E) CD patients and in (D) healthy controls. ADAM17 also is co-localized with IL-15Rα in (H) CD patients and not in (G) healthy controls. Immunostaining was specific for IL-15Rα and ADAM-17. Gastroenterology 2010 138, 2378-2387DOI: (10.1053/j.gastro.2010.02.044) Copyright © 2010 AGA Institute Terms and Conditions

Figure 6 (A) Dose-response curve of IFX. Serial 10-fold dilutions (final concentrations, 0.01–100 μg/mL) of anti-TNFα agents were added to each well. HT-29 cells were incubated in RPMI 1640 with 10% fresh human serum in 24-well culture plates for 6 hours at 37°C in a 5% CO2 incubator. Supernatants were collected, cleared, and sIL-15Rα was measured by radioimmunoassay. Values are the mean ± SD. IFX induced a secretion of sIL-15Rα in a dose-dependent manner from 0.01 to 100 μg/mL and reached a plateau at 1 μg/mL. (B) sIL-15Rα secretion by epithelial cell line HT-29. Cells were cultured in medium supplemented with IFX with or without GM-6001 or GM-6001neg. sIL-15Rα secretion increased significantly when cells were cultured in the presence of IFX compared with the cells cultured in the absence of IFX. The sIL-15Rα secretion was significantly lower when cells were incubated with GM-6001 during IFX treatment compared with cells cultured in the presence of IFX alone. (C and D) Cells were cultured in medium supplemented with etanercept or adalimumab with or without GM-6001. sIL-15Rα secretion was not modified when cells were cultured in the presence of GM-6001 alone compared with control cells or supplemented with etanercept or adalimumab. Even at 100 μg/mL of etanercept or adalimumab only a low level of sIL-15Rα was detected in the culture supernatant. Gastroenterology 2010 138, 2378-2387DOI: (10.1053/j.gastro.2010.02.044) Copyright © 2010 AGA Institute Terms and Conditions