IL-10-inducing adjuvants enhance sublingual immunotherapy efficacy in a murine asthma model.

BACKGROUND: IL-10-inducing adjuvants could enhance the efficacy of allergy vaccines in establishing allergen-specific tolerance. The aim of this study was to identify such adjuvants using in vitro cultures of human and murine cells and to evaluate them in a therapeutic murine model of sublingual immunotherapy (SLIT). METHODS: Adjuvants stimulating IL-10 gene expression by human or murine immune cells were tested sublingually in BALB/c mice sensitized to ovalbumin (OVA), assessing the reduction in airway hyperresponsiveness (AHR) by whole-body plethysmography. The induction of regulatory T cells (T(reg)) was evaluated using phenotypic and functional assays. T-cell proliferation in cervical lymph nodes (LNs) was assessed following intravenous transfer of CFSE-labelled OVA-specific T cells and FACS analysis. RESULTS: A combination of 1,25-dihydroxyvitamin D3 plus dexamethasone (VitD3/Dex) as well as Lactobacillus plantarum were found to induce IL-10 production by human and murine dendritic cells (DCs). The former inhibits LPS-induced DC maturation, whereas L. plantarum induces DC maturation. Following stimulation with VitD3/Dex-pretreated DCs, CD4+ naïve T cells exhibit a T(reg) profile. In contrast, a Th1/T(reg) pattern of differentiation is observed in the presence of DCs treated with L. plantarum. Both adjuvants significantly enhance SLIT efficacy in mice, in association with either induction of Foxp3+ T(reg) cells (for VitD3/Dex) or proliferation of OVA-specific T cells in cervical LNs (for L. plantarum). CONCLUSIONS: Both VitD3/Dex and L. plantarum polarize naïve T cells towards IL-10-expressing T cells, through distinct mechanisms. As adjuvants, they both enhance SLIT efficacy in a murine asthma model.

A synthetic triacylated pseudo-dipeptide molecule promotes Th1/TReg immune responses and enhances tolerance induction via the sublingual route.

In this study, we tested two triacylated pseudo-dipeptidic molecules, OM-197-MP-AC and OM-294-BA-MP as candidate adjuvants for allergy vaccines. Both molecules induce human dendritic cell (h-DC) maturation and polarize naïve T cells toward the Th1 type with IFNgamma production. Only OM-294-BA-MP induces IL10 gene expression both in monocyte-derived DCs and CD4+ naïve T cells. Sublingual administration of OM-294-BA-MP plus the antigen enhances tolerance induction in BALB/c mice with established asthma to ovalbumin with an impact on both airways hyperresponsiveness and lung inflammation. Given its Th1/Treg polarizing properties, OM-294-BA-MP is a valid candidate for sublingual allergy vaccines.

Improvement of sublingual immunotherapy efficacy with a mucoadhesive allergen formulation.

BACKGROUND: Sublingual immunotherapy is a noninvasive and efficacious treatment of type I respiratory allergies. A murine model of sublingual immunotherapy is needed to understand better the immune mechanisms involved in successful immunotherapy and to assess second-generation candidate vaccines. OBJECTIVE: Herein, we developed a therapeutic murine model of sublingual immunotherapy in which we document the value of mucoadhesive formulations to enhance treatment efficacy. METHODS: BALB/c mice were sublingually treated with soluble or formulated ovalbumin before or after sensitization with ovalbumin. Airways hyperresponsiveness and lung inflammation were assessed by whole-body plethysmography and lung histology, respectively. Humoral and cellular immune responses were monitored by ELISA and ELISPOT techniques. RESULTS: Prophylactic sublingual administration of ovalbumin completely prevents airways hyperresponsiveness as well as IL-5 secretion and IgE induction. Therapeutic administration of ovalbumin as a solution via either the sublingual or oral route has a limited efficacy. In contrast, sublingual application of ovalbumin formulated with maltodextrin to enhance mucosal adhesion results in a major reduction of established airways hyperresponsiveness, lung inflammation, and IL-5 production in splenocytes. This mucoadhesive formulation significantly enhances ovalbumin-specific T-cell proliferation in cervical but not mesenteric lymph nodes, and IgA production in the lungs. CONCLUSION: A mucoadhesive maltodextrin formulation of ovalbumin enhances priming of the local mucosal immune system and tolerance induction via the sublingual route. CLINICAL IMPLICATIONS: Mucoadhesive formulations offer the opportunity to improve dramatically sublingual immunotherapy in human beings, most particularly by simplifying immunization schemes.

Excipient effects on in vitro cytotoxicity of a novel paclitaxel self-emulsifying drug delivery system.

Paclitaxel is a potent chemotherapeutic agent currently administered intravenously in polyoxyethylated castor oil (Cremophor EL) and dehydrated ethanol (1:1) for the treatment of solid tumors. The objective of this work was to develop a novel self-emulsifying drug delivery system (SEDDS) devoid of cremophor for the i.v./oral delivery of paclitaxel and to investigate the in vitro cytotoxicity of the combined excipients. The SEDDS formulations were characterized in terms of droplet size using a ternary phase diagram. The Caco-2 cell line was used to monitor the cytotoxicity of the excipients. Cell viability was determined colorimetrically at 570 nm utilizing the MTT assay. The distribution of the formulations on the phase diagram indicated the presence of macroemulsions ( approximately 1 microm), submicron emulsions (50-200 nm), and microemulsions (below 10 nm). An increase in the sodium deoxycholate excipient content led to an increase in physical stability but caused more chemical degradation of the drug and more cytotoxicity. The drug in the novel SEDDS was chemically stable for at least 1 year when kept as a two-part formulation. The drug loading was increased by approximately fivefold compared to the marketed i.v. formulation; the excipients presented a significantly reduced cytotoxicity and led to a stable microemulsion.