In the present study, we conducted an study on efficacy and safety of NVP-1703 in patients with symptomatic allergic rhinitis. NVP-1703 significantly improved the clinical outcomes such as TNSS and RCAT questionnare. NVP-1703 was especially effective to reduce watery rhinorrhea, nasal congestion, tear symptom and sleep disorder. NVP-1703 also significantly improved various anti-allergic immunologic profiles such as speific IgE for Dp and Df, PGF2a as well as IL-10, IL-10/IL-4 ratio and IL-10/IL-5 ratio. We can postulate that NVP-1703 can affect the key immunologic markers associated with allergic rhinitis, which subsequently results the improvement of symptoms in allergic rhinitis.

Although several studies had been conducted to evaluate the efficacy of probiotics in allergic rhinitis, previous studies had some limitations. First, previous studies evaluated the limited efficacies of probiotics in maintaining medication for allergic rhinitis such as intranasal steroid or oral antihistamines. Because many patient with AR did not continue the medication despite suffering from rhinitis symptoms in real life, it is not appropriate to evaluate the effects of probiotics on allergic rhinitis in real world. Second, previous studies have used the Quality of Life assessment rather than the TNSS evaluation. However, the Quality of Life assessment may be insufficient in accurately evaluating the efficacies of anti-AR drugs and probiotics. Third, most previous studies evaluate the efficacies of single probiotic strain reported to be effective in preliminary animal studies including Bifidobacterium lactis, Bifodibaterium longum, lactobacillus plantatrum, and Lactobacillus paracasei. However, the effects of single probiotic strain on allergic rhinitis had not been consistent. Recently, there have been attempts to mix different probiotic strains that had been shown to have anti-allergic effects on animal study. However, these studies were also combined different strains within the same species (e.g., Bifidobacterium longum BB536, Bifidobacterium infantis M63, and Bifidobacterium breve M-16V in study of Miraglia's et al.) At this point, our study has some distint advantages on study design from previous studies. NNVP-1703, the probiotic mixture of Bifidobacterium longum IM55, which was selected from human gut bacteria collection as an regulatory T cell regulator, and Lactobacillus plantarum IM76, which was from the fermented food bacteria collection as a macrophage NF-κB inhibitor, significantly regulates innate and adaptive immunity in animal and in vitro studies[27,28]. We investigated whether NVP-1703 could significantly improve the various symptoms and quality of patients with persistent rhinitis symptoms without other controller medication. NVP-1703 significantly alleviated TNSS and RCAT scores and allergic cytokine levels. To date, NVP-1703 is the first probiotic mixtures that have been proven efficacies in patients with symptomatic AR without any rescue medication.

The improvement of clinical outcomes in NVP-1703 group seemed to be related to the improvement of anti-allergic immunologic profiles. Blood IL-10 levels were significantly higher and blood IL-4, IL-5, IL-13 levels were also significantly lower in NVP-1703 group. The ratios of IL-10/IL-4, IL-10/IL-5, and IL-10/IL-13 were also increased in the NVP-1703 group. IL-4, IL-5 and IL-13 is an important allergy-prone cytokines involved in many steps of allergic inflammation. IL-10 is an important counter-regulatory cytokines required to control allergic inflammations. IL-10-mediated regulation of T-cell mediated reponses directly regulate T helper type 2 (Th2 cells) and subsequently decrease the IL-4, IL-5 and IL-13 levels in blood. Tomiita et al reported that the ratio of IL-10/IL-5 was significantly increased in a healthy control group when compared to active asthma and remission groups [42]. Aslam et al. reported that immunotherapy in patients with wasp-vinon allergy increased the ratio of IL-10/IL-4 [43]. The administration of NVP-1703 significantly suppresses the expression of IL-4 and IL-5 and the differentiation of T cells into Th2 cells in mice with ovalbumin (OVA)- and house dust mite allergen extract (HDMA)-induced AR, while the expression of IL-10 and the differentiation of T cells into Treg cells are increased [27,28]. These results suggest that the administration of NVP-1703 can suppress the expression of Th2 cytokines IL-4 and IL13 and eosinophil cytokine IL-5 by inducing the IL-10 expression, a Treg cell cytokine, and Treg cell differentiation. These changed profiles of cytokines from NVP-1703 treatment appeared to be similar to the changes from allergen immunotherapy, which is a disease modifying immune-modulatory treatment.

NVP-1703 treatment also inhibited IgE levels, particularly Df- and Dp-secific IgEs, in the blood of individuals with AR. IL-10 indirectly facilitates IL-4-induced IgG4 production in human B cells together with the suppression of IgE [44]. IL-10 inhibits IgE-induced activation of human mast cells directly in vitro [45]. The induction of IL-10 expression suppresses the expression of IgE receptors in mast cells [46]. There results suggest that the induction of IL-10 expression by NVP-1703 can suppress the production of IgE including Dp- and Df-specific IgE production. The NVP-1703-treated group also showed a significant decrease in PGF2 in the urine compared to the placebo group after 4 weeks of ingestion. The NVP-1703-treated group also showed a significant decrease in PGF2a and LTE4 in urine. LTE4 and PGF2a produced in the early phase of the allergic inflammation [49] and are biomarkers of eosinophil or mast cell activation[50,51]. These lipid mediators are very important in the pathological mechanisms of allergic rhinitis [2]. These mediators increase venous engorgement and tissue swelling/edema, leading to concomitant rhinorrhea and nasal congestion [52,53]. Leukotriene receptor antagonist exert their action by blocking potent lipiod mediators LTE4. These results suggest that the administration of NVP-1703 stabilizes eosinophils through the action of reducing the amount of inflammatory mediators, thus contributing the improvement of symptoms of allergic rhinitis including nasal discharge and nasal congestion.

There were several limitations in our study.

The present research focused on the efficacy of NVP-1703 in human clinical trials of perennial AR. The duration and period of probiotic intake are important. It was shown that beneficial effects of probiotics are seen at least 4 weeks after continuous administration (ref). Therefore, to clearly dissolve its anti-allergic effectiveness, further researches on the active components of NVP-1703, the efficacy of NVP-1703 with rescue medication and for a long-term supplementation are necessary.

In conclusion, NVP-1703 can reduce the secretion of IL-4, IL-5, IL-13, IgE, PGD2, and LTE4 and induce IL-10 expression by suppressing the activation of mast cells, eosinophils, Th2 cells, and B cells through the induction of Treg cells, resulting in the attenuation of allergic rhinitis symptoms.