Asthma is a heterogeneous respiratory syndrome of the lung airways characterized by intermittent episodes of wheezing and coughing [1], [2]. It affects nearly 334 million people worldwide [3]. Asthma is a disease associated prototypically with hyper activation of Th2 arm of adaptive immunity and orchestrated primarily by the network of Th2 cytokines including IL-4, IL-5 and IL-13 resulting in infiltration of inflammatory cells mainly eosinophils and lymphocytes in the lungs [4], [5]. GATA-3 and STAT-6 plays a critical role in differentiation of Th2 cells from naive CD4+ T cells [6] and regulate hyper-mucus production and airway-hyperresponsiveness (AHR) under asthmatic conditions [7].

Corticosteroids along with long-acting β2-agonists and leukotriene receptor antagonists are highly recommended and well recognized drugs for the management of asthma [8]. However, 5–10 % of patients suffering from severe asthma are relatively resistant to these treatments [9]. Moreover, a significant proportion of patients experience numerous side effects upon prolonged use of steroids/drugs [10]. Thus, there is need for the development of new intervention strategies for asthma that are safe or are associated with minimal side effects.

In recent times, it has been observed that decline in gut microbial diversity plays a critical role in the pathophysiology of asthma by triggering various inflammatory responses [11], [12], [13], [14], [15], [16]. Gut microbiota represent the most relevant source for the development of the immune system in infants and hence the microbial imbalance has been linked with the rise in allergic disorders including asthma [17]. Therefore, restoring microbiota balance through probiotics administration has emerged as a beneficial and safe strategy in amelioration of asthma [18], [19], [20], [21], [22]. Bifidobacteria, along with lactobacilli, are an important part of normal intestinal microbiota and are well characterized and widely commercialized probiotics. Bifidobacteria, along with lactobacilli, are an important part of normal intestinal microbiota and are well characterized and widely commercialized probiotics. Lactobacillus and Bifidobacterium are the lactic acid producing bacterial (LAPB) strains [23]. Important functional properties of LAPB strains include their resistance to acidic gastric juices, capacity of adhesion to the walls of the gastrointestinal tract and antagonistic action against pathogenic microorganisms which might endanger the human [24]. LAPB strains usually ferment carbohydrate substrates to produce lactic acid and short chain fatty acids (SCFAs) such as butyric acid, acetic acid or propionic acid lowering the pH of the intestinal contents [25], [26]. In addition, some lactic acid bacteria secrete substances with a bacteriostatic effect such as H2O2 and bacteriocins called lactocins (e.g. nisin, acidophilin, lactacin, lactocidin) thus preventing their own ecological niche and development of pathogenic micro-organisms [27], [28], [29]. Synbiotic comprising of probiotics and non-digestible dietary fibers (prebiotics) in diet, simulate conditions for improved fermentation resulting in production of SCFAs including acetate, propionate and butyrate [30], [31], [32], [33], [25]. SCFAs are kindred with innumerable immunomodulation properties especially differentiation/promotion of T-regulatory (T-reg) cells which, as a consequence, reduces inflammation [34]. In this regard, various studies showed that restoring gut microbiota by addition of probiotics and prebiotics confers protection to the host by regulating the immune system through their immune modulatory properties [12], [16], [35]. However, the efficacy of the probiotics is well known to be species and strain specific [36], [37]. Further, probiotic strains vary according to the geographical region which may limit their global application. Significant differences have been observed in the composition of fecal microbiota between individuals living in Amazonas of Venezuela, rural Malawi and US metropolitan areas [38]. Geographical location has an impact on the microbial populations due to prominent differences in diet across regions. A comparative study in children from Europe and rural Africa where there is intake of high fiber diet showed suppression in pathogenic bacteria among African children as compared to European children. Moreover, the ratio of Firmicutes/Bacteroidetes was found to be different among two populations [39]. Present day human beings are genetically modified to the environment in which their ancestors survived and which conditioned their genetic makeup. So, local strains may suit the patients in a region specific manner. The role of gut microbiota in allergy and inflammatory diseases has been highly addressed in western world but studies in the developing world are extremely limited. Therefore, it is imperative to test new probiotic strains, which may be useful to people residing in that particular region/country. Accordingly, the present work was designed to assess the protective efficiency of newly isolated bacterial strains i.e. Bifidobacterium breve Bif11 and Lactiplantibacillus plantarum LAB31 in asthma pathogenesis relevant with Indian population. These strains have been isolated from the feces of infants around Tricity region (Chandigarh, Mohali, Panchkula), India. Lipopolysaccharide (LPS) is a gut-transmitted endotoxin from Gram-negative bacteria, causes inflammatory diseases leading to the loss of gut barrier integrity and has been identified as a major pathogenic stimulator in many dysfunctions [40]. Interestingly, these strains have shown promising beneficial effect in amelioration of inflammation associated with ulcerative colitis and lipopolysaccharide (LPS)-induced gut inflammation and dysbiosis in mice [41], [42]. Given the anti-inflammatory effects of B. breve Bif11 and L. plantarum LAB31, we hypothesized that these strains might ameliorate allergen induced asthmatic features through modulation of immune response. After establishing the beneficial effects of both strains, we next examined the impact of oral supplementation of both individual strains on various molecular players that are known to play a critical role in orchestration of events leading to manifestation of allergic asthma in mice. Finally, our data clearly shows that a synbiotic comprising of Bif11, LAB31 and a prebiotic, Isomaltooligosaccharide (IMOS) has the ability to ameliorate various features of allergic asthma quite remarkably.