Epicutaneous Immunotherapy Compared with Sublingual Immunotherapy in Mice Sensitized to Pollen (Phleum pratense)

Abstract

Background. The aim of this study was to compare the efficacy of epicutaneous immunotherapy (EPIT) to sublingual immunotherapy (SLIT) in a model of mice sensitized to Phleum pratense pollen. Methods. BALB/c mice were sensitized by sub-cutaneous route to pollen protein extract mixed treated for 8 weeks, using sham, EPIT, or SLIT. Measurements involved the serological response and cytokine profile from reactivated splenocytes, plethysmography after aerosol challenge to pollen, cell, and cytokine contents in the bronchoalveolar lavages (BALs). Results. After immunotherapy, sIgE was significantly decreased in the treated groups compared to sham (P < 0.001), whereas sIgG2a increased with EPIT and SLIT (P < 0.001 and P < 0.005 versus sham). Reactivated splenocytes secreted higher levels of Th2 cytokines with sham (P < 0.01). Penh values were higher in sham than EPIT and SLIT. Eosinophil recruitment in BAL was significantly reduced only by EPIT (P < 0.01). Conclusion. In this model of mice sensitized to pollen, EPIT was at least as efficient as SLIT.

Figure 1

Study design. Mice were sensitized to pollen proteins by 3 subcutaneous injections, with aluminium hydroxide as adjuvant, separated at 1-week interval. Immunotherapy was conducted during 8 weeks with one treatment per week: one sublingual administration or one 48-h application of Viaskin epicutaneous delivery system. Blood was sampled before immunotherapy (D0) to validate the phase of sensitization and during immunotherapy (D21, D38, D63).

Figure 2

Ex vivo cytokine production of spleen cells restimulated with Phl p extract (100 μg/mL). Treatment groups were EPIT (epicutaneous immunotherapy), SLIT (sublingual immunotherapy), sham (sensitized not treated), and C (control, not sensitized, and not treated). *P < 0.05, **P < 0.01, ***P < 0.001.

Figure 3

Recruitment of eosinophils in the BAL fluid measured 48 h after the last aerosol challenge. Treatment groups were EPIT (epicutaneous immunotherapy), SLIT (sublingual immunotherapy), sham (sensitized not treated), and C (control, not sensitized and not treated). *P < 0.05, **P < 0.01, ***P < 0.001.

Figure 4

Th2 cytokines (IL-4 (a) and IL-5 (b)) measured in the BAL fluid. After the sensitization and treatment periods, mice were challenged by aerosol during 3 consecutive days. Forty-eight hours after the last challenge, BAL fluids were collected. Treatment groups were EPIT (epicutaneous immunotherapy), SLIT (sublingual immunotherapy), sham (sensitized not treated), and C (control, not sensitized, and not treated). *P < 0.05, **P < 0.01, ***P < 0.001.

Figure 5

Airway hyperresponsiveness after immunotherapy. Mice were exposed to increasing doses of methacholine the day following the last 30-minute aerosol challenge: (a) dose-response curves and (b) individual area under the curve (AUC) calculated from data of graph (a) Treatment groups were EPIT (epicutaneous immunotherapy), SLIT (sublingual immunotherapy), sham (sensitized not treated), and C (control, not sensitized, and not treated). *P < 0.05, **P < 0.01, ***P < 0.001.