Efficacy of epicutaneous immunotherapy (EPIT) in a new model of peanut-induced eosinophilic esophagitis (EoE) and allergic enterpathy (AE)

Background Eosinophilia is often linked to allergic gastrointestinal disorders linked to food allergy. EPIT using Viaskin® device has been described as a therapeutic method in food allergy. We developed a model of mice sensitized to peanut, exhibiting EoE and AE after exclusive feeding with peanut protein extracts (PPE). This study was conducted in order to evaluate the efficacy of EPIT. Methods After oral sensitization with PPE and cholera toxin, 30 BALB/c mice were treated weekly during 8 weeks by PPE skin applications (EPIT), 20 mice were not treated (Sham) and 10 mice constituted the control group (C). Mice were then exclusively fed with PPE. Specific IgE, IgG1 and IgG2a were monitored during immunotherapy. Esophageal and jejunal samples were taken for histological analyses. Results sIgE increased after oral sensitization, respectively 0.207 ±0.03 and 0.214±0.04 μg/ml, in EPIT and Sham, with undetectable values in C. Following EPIT, sIgE decreased and sIgG2a increased, respectively 0.139±0.01 vs 0.166±0.01 μg/ml (EPIT vs Sham, p<0.05) and 14.96 ±0.60 vs 4.73±1.75 μg/ml (p<0.05). Esophageal eosinophilic infiltration (measured in 6 high power fields) was higher in Sham, 136±32, than in EPIT, 50±12 (p<0.05) and C, 7±3 cells/mm2 (p<0.01). Esophagus mucosa thickness was increased in Sham compared to EPIT and C (p<0.001). Sham group exhibited higher mRNA levels of cytokines than EPIT: eotaxin (p<0.05), IL-5 (p<0.05), IL-13 (p<0.05). The mRNA levels of these cytokines in EPIT were similar to C. The expression of Foxp3 mRNA increased significantky after EPIT compared with Sham and C (p<0.05). The jejunal villus/crypt ratio was lower in Sham than in EPIT and C, respectively 1.6 ±0.1 vs 2.3±0.2 (p<0.01) and 2.4±0.1 (p<0.001). Eosinophilic infiltration in jejunum was increased in Sham compared to EPIT (p<0.01) and C (p<0.001). Conclusion EPIT is effective in preventing EoE and AE induced by oral challenge in mice sensitized to peanut

Epicutaneous Immunotherapy (EPIT) Blocks the Allergic Esophago-Gastro-Enteropathy Induced by Sustained Oral Exposure to Peanuts in Sensitized Mice

Background: Food allergy may affect the gastrointestinal tract and eosinophilia is often associated with allergic gastrointestinal disorders. Allergy to peanuts is a life-threatening condition and effective and safe treatments still need to be developed. The present study aimed to evaluate the effects of sustained oral exposure to peanuts on the esophageal and jejunal mucosa in sensitized mice. We also evaluated the effects of desensitization with epicutaneous immunotherapy (EPIT) on these processes. Methods: Mice were sensitized by gavages with whole peanut protein extract (PPE) given with cholera toxin. Sensitized mice were subsequently exposed to peanuts via a specific regimen and were then analysed for eosinophilia in the esophagus and gut. We also assessed mRNA expression in the esophagus, antibody levels, and peripheral T-cell response. The effects of EPIT were tested when intercalated with sensitization and sustained oral peanut exposure. Results: Sustained oral exposure to peanuts in sensitized mice led to severe esophageal eosinophilia and intestinal villus sub-atrophia, i.e. significantly increased influx of eosinophils into the esophageal mucosa (136 eosinophils/mm2) and reduced villus/crypt ratios (1.660.15). In the sera, specific IgE levels significantly increased as did secretion of Th2 cytokines by peanut-reactivated splenocytes. EPIT of sensitized mice significantly reduced Th2 immunological response (IgE response and splenocyte secretion of Th2 cytokines) as well as esophageal eosinophilia (50 eosinophils/mm2, p,0.05), mRNA expression of Th2 cytokines in tissue - eotaxin (p,0.05), IL-5 (p,0.05), and IL-13 (p,0.05) -, GATA-3 (p,0.05), and intestinal villus sub-atrophia (2.360.15). EPIT also increased specific IgG2a (p,0.05) and mRNA expression of Foxp3 (p,0.05) in the esophageal mucosa. Conclusions: Gastro-intestinal lesions induced by sustained oral exposure in sensitized mice are efficaciously treated by allergen specific EPIT

Antigen Uptake by Langerhans Cells Is Required for the Induction of Regulatory T Cells and the Acquisition of Tolerance During Epicutaneous Immunotherapy in OVA-Sensitized Mice

The skin is a major immunologic organ that may induce protection, sensitization or tolerance. Epicutaneous immunotherapy (EPIT) has been proposed as an attractive strategy to actively treat food allergy and has been shown to induce tolerance in sensitized mice through the induction of Foxp3+ regulatory T cells (Tregs), especially CD62L+ Tregs. Among immune cells in the skin, dendritic cells are key players in antigen-specific immune activation or regulation. The role of different populations of skin DCs in tolerance induction remains to be elucidated. Using OVA-sensitized BALB/c mice, we demonstrated that the application of a patch containing OVA-A647 to the skin resulted in allergen uptake by Langerhans cells (LCs) and CD11b+ dermal cDC2 and subsequent migration into skin draining lymph nodes. These 2 populations induced Foxp3 expression in CD4+ cells in vitro. Only LCs induced LAP+ cells and CD62L+ Tregs. Using Langerin-eGFP-DTR mice, we analyzed the role of LCs in the mechanisms of tolerance induction by EPIT in vivo. Following complete depletion of LCs, a dramatic decrease in the number of OVA+ DCs and OVA+ CD11b+ dermal cDC2 was observed in skin draining lymph nodes 48 h after epicutaneous application. Likewise, 2 weeks of EPIT in non-depleted mice induced Foxp3+ Tregs, especially CD62L+, and LAP+ Tregs in skin draining lymph nodes and spleen, whereas no induction of Tregs was observed in LC-depleted mice. Following 8 weeks of treatment, EPIT-treated mice showed significant protection against anaphylaxis accompanied by a significant increase of Foxp3+ Tregs, especially CD62L+ Tregs, which was not seen in the absence of LCs. In summary, although both LCs and CD11b+ dermal cDC2s could induce regulatory T cells, the absence of LCs during EPIT impaired treatment efficacy, indicating their crucial role in skin-induced tolerance

Human peritoneal mesothelial cells respond to bacterial ligands through a specific subset of Toll-like receptors

Background. Bacterial infection remains a major cause of morbidity and mortality in peritoneal dialysis (PD) patients worldwide. Previous studies have identified a key role for mesothelial cells, lining the peritoneal cavity, in coordinating inflammation and host defense. Toll-like receptor (TLR) involvement in early activation events within the mesothelium, however, remains poorly defined. To investigate the initiation of bacterial peritonitis, we characterized TLR activation by bacterial ligands in human peritoneal mesothelial cells (HPMC)

Etude des activités antivirales solubles non cytolytiques des lymphocytes CD8+ au cours de l'infection par SIV (Effet d'un traitement par polychimiothérapie post-exposition, effet d'un traitement immuno-modulateur par l'interleukine 2 et mécanismes de reconstitution lymphocytaire T CD4+)

LE KREMLIN-B.- PARIS 11-BU Méd (940432101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Intact skin and not stripped skin is crucial for the safety and efficacy of peanut epicutaneous immunotherapy (EPIT) in mice

<p>Abstract</p> <p>Background</p> <p>Epicutaneous immunotherapy (EPIT) on intact skin with an epicutaneous delivery system has already been used in preclinical and clinical studies. In epicutaneous vaccination and immunotherapy, the stripping of skin before application of the allergen is suggested to facilitate the passage of allergen through immune cells.</p> <p>Objectives</p> <p>The aim of this study was to compare the immunological response induced by EPIT performed on intact and stripped skin in a mouse model of peanut allergy.</p> <p>Methods</p> <p>After oral sensitization with peanut and cholera toxin, BALB/c mice were epicutaneously treated using an epicutaneous delivery system (Viaskin® (DBV Technologies, Paris) applied either on intact skin or on stripped skin. Following EPIT, mice received an exclusive oral peanut regimen, aimed at triggering esophageal and jejunal lesions. We assessed eosinophil infiltration by histology, mRNA expression in the esophagus, antibody levels and peripheral T-cell response.</p> <p>Results</p> <p>EPIT on intact skin significantly reduced Th2 immunological response (IgE response and splenocyte secretion of Th2 cytokines) as well as esophageal eosinophilia (2.7 ± 0.9, compared to Sham 19.9 ± 1.5, p < 0.01), mRNA expression of Th2 cytokines in tissue and intestinal villus sub-atrophia (2.9 ± 0.2 vs Sham, 2.1 ± 0.2, p < 0.05). By contrast, EPIT on stripped skin reinforced Th2 systemic immunological response as well as eosinophil infiltration (26.8 ± 15.1), mRNA expression of Th2 cytokines and duodenal villus/crypt-ratio (2.4 ± 0.3).</p> <p>Conclusions</p> <p>Epicutaneous allergen-specific immunotherapy needs the integrity of superficial layers of the stratum corneum to warranty safety of treatment and to induce a tolerogenic profile of the immune response.</p

Changes in Soluble Factor-Mediated CD8(+) Cell-Derived Antiviral Activity in Cynomolgus Macaques Infected with Simian Immunodeficiency Virus SIVmac251: Relationship to Biological Markers of Progression

Cross-sectional studies have shown that the capacity of CD8(+) cells from human immunodeficiency virus (HIV)-infected patients and simian immunodeficiency virus (SIV) SIVmac-infected macaques to suppress the replication of human and simian immunodeficiency viruses in vitro depends on the clinical stage of disease, but little is known about changes in this antiviral activity over time in individual HIV-infected patients or SIV-infected macaques. We assessed changes in the soluble factor-mediated noncytolytic antiviral activity of CD8(+) cells over time in eight cynomolgus macaques infected with SIVmac251 to determine the pathophysiological role of this activity. CD8(+) cell-associated antiviral activity increased rapidly in the first week after viral inoculation and remained detectable during the early phase of infection. The net increase in antiviral activity of CD8(+) cells was correlated with plasma viral load throughout the 15 months of follow-up. CD8(+) cells gradually lost their antiviral activity over time and acquired virus replication-enhancing capacity. Levels of antiviral activity correlated with CD4(+) T-cell counts after viral set point. Concentrations of β-chemokines and interleukin-16 in CD8(+) cell supernatants were not correlated with this antiviral activity, and α-defensins were not detected. The soluble factor-mediated antiviral activity of CD8(+) cells was neither cytolytic nor restricted to major histocompatibility complex. This longitudinal study strongly suggests that the increase in noncytolytic antiviral activity from baseline and the maintenance of this increase over time in cynomolgus macaques depend on both viral replication and CD4(+) T cells

No impact of filaggrin deficiency on the efficacy of epicutaneous immunotherapy in a murine model

Background: Epicutaneous immunotherapy (EPIT&reg;), currently investigated in the treatment of food allergy, needs the integrity of the skin to warrant safety and efficacy. Mutations in the gene encoding the key epidermal protein filaggrin (FLG) are risk factors for peanut allergy and disrupt the skin intergrity. We investigated the association between FLG deficiency and peanut EPIT&reg; efficacy in a murine model. Methods: FLG mutant mice deficient in filaggrin (FLG-/-) or wild-type (WT) mice were sensitized with peanut protein extract (peanut protein) and cholera toxin. Sensitized mice received a patch per week during 8 weeks for EPIT&reg;, using Viaskin&reg;, and were then submitted to sustained peanut oral exposure. We assessed blood humoral and cellular responses and evaluated eosinophil infiltration in the gut mucosa. The different steps of allergen capture and transportation following deposition on the skin was also analyzed in sensitized mice. Results: Sensitization of mice was confirmed by a significant increase of specific Th2 biaised immunological responses. In sensitized mice, EPIT&reg; significantly reduced IgE levels, splenocytes secretion of Th2 cytokines and recruitment of eosinophils in esophagus, compared to sensitized mice without epicutaneous immunotherapy. The allergen applied onto the skin of FLG-/- mice did not undergo passive skin passage or systemic delivery. Instead, the allergen was captured by skin CD205high&nbsp;DCs, which migrated to afferent lymph nodes, as already described in WT mice. Conclusions: EPIT&reg; was efficient and safe in FLG-/- mice, suggesting that in Humans EPIT&reg; keeps efficacy and safety in the presence of loss of function of FLG

Unique epigenetic signature in T cell compartment after epicutaneous immunotherapy in peanut sensitized mice

International audienceRationale Epicutaneous immunotherapy (EPIT) induces naïve Tregs, which play a crucial role in the bystander effect identified in a model of food allergic mice. Previously, EPIT was shown to alter epigenetic modifications and expression of Th2 and Tregs without influencing the expression of Th1 in peanut-sensitized mice. This study investigates methylation modifications occurring in specific T cell compartments. Methods Mice were orally sensitized to peanut and then treated with EPIT or non-treated. Mice were sacrificed at the end of treatment or 8 weeks after the end of immunotherapy. Regulatory T cells (CD62L+Foxp3+ and CD62L-Foxp3+) were sorted directly from the spleen and Th2 and Th1 cells were purified after a short in vitro reactivation of splenocytes. DNA methylation at Gata3 promoter and Foxp3 CNS2 was analysed in all sorted cells by pyrosequencing. Results Epicutaneous immunotherapy did not modify proportions of Th1 and Th2 cells in the spleen. The hypermethylation of CpG islands of Gata3 only occurred in Th2 cells for EPIT-treated mice at the end of immunotherapy and was sustained 8 weeks later (p<0.05 vs Sham). In parallel, significant hypomethylation was observed in the Foxp3 CpG islands of naïve Tregs only (p<0.05), not effector Tregs, at the end of EPIT, and persisted for 8 weeks following the end of treatment (p<0.001). Conclusions The unique epigenetic signature of EPIT is confirmed at cellular level for Gata3 (Th2) and Foxp3 (naïve Tregs), suggesting the induction of tolerance and prevention of further sensitization. Foxp3 hypomethylation occurring only on naïve Tregs underlines the crucial role of EPIT-induced naïve Tregs