Keywords

13.1 Introduction

13.1.1 Probiotics

The World Health Organization (WHO) defined probiotic as “living microorganisms in adequate amount confer the health benefits” (Food and Agriculture Organization of the United Nations, World Health Organization 2002). The phrase “probiotic” is a Greek term and means “for life.” Originally it was termed as “substances secreted by one microorganism that stimulate the growth of another” (Lilly and Stillwell 1965). The redefinition by Parker (1974) coined the probiotics as “organisms and substances, which contribute to intestinal microbial balance.”

The adapted narration by Fuller (1989) stated as “a live microbial feed supplement, which beneficially affects the host animal by improving its microbial balance.” Marteau et al. (2001) provided the most accepted definition as “microbial cell preparations or components of microbial cells that have a beneficial effect on the health and well-being.”

The Food Safety Department, World Health Organization (2005) defined probiotics as “live microorganisms, which, when administered in adequate amounts, confer a health benefit on the host.” The international scientific community has admitted to this and has become the working definition of probiotics.

The most commonly used probiotics are lactic acid bacteria (LAB), particularly Lactobacillus and Bifidobacterium species, followed by the genera Enterococcus, Streptococcus, Propionibacterium, Pediococcus, Escherichia coli, and Bacillus (Szajewska et al. 2016). Few some yeast species are having potential as probiotics, e.g. Saccharomyces cerevisiae and Saccharomyces boulardii were utilized for the treatment of gastrointestinal diseases very often (Guarner et al. 2012; Sanders et al. 2013; Schreck Bird et al. 2017; Kerry et al. 2018). However, not all the bacteria can be probiotic, as they need to be strain-specific.

The probiotic produce is in the type of tablets, capsules, powders (which worked as a dietetic complement), and as a food component (e.g., kefirs, kombucha, tempeh, miso, yogurts, or a drug). The dairy products and functional foods are helpful for the restoration of healthy microbiota of the body and almost all adults, as well as children, consumed it (Reid 2015). Hence dairy probiotic has been commercialized all over the world in different forms. However, allergy and lactose intolerance are the main arrests of dairy probiotics. The milk proteins, casein and whey proteins may act as allergens (Kumar et al. 2015).

Among the food factors, the use of food dyes is also a major reason for food allergy. Various natural and synthetic dyes such as carmine, tartrazine, and so on are added to the food to enhance the aesthetic value but may cause adverse reactions of food coloring allergy (Laura et al. 2019).

Probiotics are the indigenous nonpathogenic bacteria that colonize the mammalian intestinal tract. 10% out of 103–104 bacteria/ml dwelling in the body are legitimate living bacteria (Sender et al. 2016). The probiotic bacteria colonize initially maternal vaginal and fecal bacteria flora with reductive potential to make an anaerobic condition to favor the development of Lactobacilli and Bifidobacteria.

13.1.2 Benefits of Probiotics

The gastrointestinal tract is one of the most microbiologically dynamic environments that assume a vital role in the working of the mucosal immune system (MIS). The consumed probiotic stimulates the immune response as well as signaling by intact bacteria or its cell wall structure (Galdeano et al. 2019).

The gut is the site where huge numbers of bacteria from the microbiota and from the intestine which get through food intake coexist with each other. The immune cells are associated with the lamina propria of the villi. This intestinal microbiota does not interrelate straightforwardly with the epithelial cells; however, the maturation and functionality of the immune cells are stimulated by this microbiota through their metabolites (Hooper et al. 2012).

The beneficial effects of probiotics have been widely used in improving the host well-being and for the treatment of diverse infectious and non-infectious pathologies in animal models. Specifically it is included: protection from infection (Park et al. 2017; Acurcio et al. 2017; Mallina et al. 2018), irritable bowel symptoms relief (Hungin et al. 2013), reduction in the gut inflammatory response (Fábrega et al. 2017), cancer prevention (Aragón et al. 2015; So et al. 2017), growth inhibition of Helicobacter pylori (Fujimura et al. 2012), and allergies prevention (Velez et al. 2015).

Even though probiotics have shown encouraging results in several health conditions in humans, such as diabetes, multi-drug resistant pathogens, irritable bowel syndrome (He et al. 2017; Abdelhamid et al. 2018; Majeed et al. 2018), extensive research is still essential to include probiotics into human health, nutrition, and regulation of diverse abnormalities.

13.1.3 How Probiotic Function for Immune System?

The primary clause for probiotic microbes is survival in the harsh conditions of the gastrointestinal (GI) tract and stomach of humans. There are various ways by which probiotic microbes modulate the immune system. Figure 13.1 presents a brief of the role of probiotics for the immune system to maintain the human health majorly include: i) Modulation of innate and adaptive immunity, ii) Growth inhibition of pathogenic bacteria, iii) Regulation of anti-inflammatory or pro-inflammatory cytokines, iv) Regulation of the gastrointestinal /mucosal immune system (Baldassarre et al. 2016).

Fig. 13.1
figure 1

Effect of probiotic on immune system

Full size image

The important properties of probiotics which help to maintain the body to exert the effects are capacity to stick to the epithelial cells, activation of innate and cytokine-mediated immune response by internalization of a fragment of probiotic bacteria inside the immune response stimulating, intestinal epithelial cells (IECs) (Galdeano and Perdigon 2004), strengthening of the intestinal barrier by increasing the number of Goblet cells which reinforce the mucus layer (De Moreno de LeBlanc et al. 2008).

Table 13.1 summarizes the diverse means to promote human health. In recent years, extensive research has been conducted on the role of probiotics in transforming the adaptive and innate immunity as a way to check or treat a wide variety of health conditions (Baldassarre et al. 2016).

Table 13.1 Summary of probiotic mechanisms to promote the human health
Full size table

Now the probiotics have been commonly considered at therapeutical and clinical research level considering the relationship between the gut microbiome and immune disorders (Kothari et al. 2019), but the clear guidelines for the clinical application have yet to be established. This is particularly significant as the efficiency of probiotic supplementation may be reliant on the strain, dosing, condition, and duration of therapy (Toscano et al. 2017).

13.2 Role of Probiotics in Allergic Airway Infection

The normal healthy microflora constitutes the basis of probiotic therapy. Probiotics commonly mentioned as “good bacteria” or like a replacement for inhabitant stomach bacteria. Although the WHO recognizes probiotics as live microbes, when consumed in adequate quantity as an ingredient of food, it provides a health benefit to the host (Food Safety Department, World Health Organization 2005). At present, any item containing probiotics is viewed as a dietetic complement and is controlled by the principles and guidelines of the Dietary Supplement Health and Education Act of 1994. As indicated by it, the producer can give just common health declare for the manufactured food however it cannot express that any of the element in the product can fix, treat, or avoid illness (Alvarez-Olmos and Oberhelman 2001).

The dysbiosis, an inequity of the microflora constitution has adversely affected the health status. Three subcategory of dysbiosis have been recognized as below: (1) beneficial microbial agents loss, (2) spreading out of potentially harmful microorganisms, and (3) overall microbial diversity loss (Petersen and Round 2014).

Microbial dysbiosis has been concerned for different chronic inflammatory diseases, together with asthma (Sutherland and Martin 2007; Smits et al. 2016), chronic rhinosinusitis (CRS) (Hoggard et al. 2017; Aurora et al. 2013), Crohn’s disease (Marin et al. 1983), and ulcerative colitis (Schmitz et al. 1999). The allergic infants reported an augmented number of Clostridia and a lower number of Bifidobacteria (Goktepe et al. 2005).

Amazingly all these persistent infections found to have altered membrane permeability and distorted functioning of epithelial barrier (Soyka et al. 2012; Steelant et al. 2016).

Probiotics have been publicized for a range of situation such as allergies, respiratory infections, including acute diarrhea, inflammatory bowel disease, and irritable bowel syndrome. This is been a choice to re-establish a healthy immune system (Dorval, 2015). Diverse probiotic strains and the mixing of microorganisms have a wide and differing range of clinical and immunologic potential and can manipulate gut microbiota in human beneficial ways (Table 13.2). The improved presence of probiotic bacteria in the intestinal microbiota has been found to correspond with defense from atopy (Moura et al. 2019). The predominance of hypersensitive ailment allergic diseases such as asthma, atopic dermatitis, and allergic rhinitis has expanded harshly over the past 2–3 decades in numerous nation, and sensitivities/allergies are presently most widely recognized chronic disease among youngsters all through the world (Tang et al. 2015).

Table 13.2 Representative studies demonstrating Probiotic effect in allergy
Full size table

The utilization of probiotic live forms could offer advantage to the patient’s immunity, prompting improved management of the ailment, along with advanced lung functioning and reduced symptoms. Moreover, another mechanism of working of the probiotics comprised the enhancement in the epithelium membrane obstruction, hindrance of the adhesion of pathogens, binding to the intestinal mucosa, prohibition from pathogenic microorganisms by rivalry, and antimicrobial substance production (Bermudez-Brito et al. 2012).

Allergic ailment represents a convincing challenge for community well-being concern due to their expanding predominance in evolved and evolving nations. Universally roughly 1 thousand million people are facing allergic symptoms and could be reached to 4 thousand million in the following 3–4 decades (Spacova et al. 2018).

Allergy is defined as a hypersensitive reaction to a particular antigen called an allergen by an immunological reaction (Ring, 2014). The commonly found allergies are against pollen grains, animal dander, mites of dust, or specific foodstuffs. Allergies are caused due to an increase in the amount of IgE (Akdis and Agache, 2014). The repeated exposure to allergen elicits activation of mast cell and basophile cells and release of allergic mediators like histamine and leukotriene resulting in five cardinal signs of allergy that vary from mild symptoms like sneezing but may become serious like difficulty in breathing and hypersensitivity.

The number of studies carried out to study the probiotic as therapy for airway allergy such as a Stockert et al. (2007) in a pilot study investigated the influence of probiotics for asthma suffering kids and discovered improved lung functioning (peak of expiratory flow [PEF]) but no effect on the quality of lives and use of asthma treatment. Furthermore, Chen et al. (2010) observed progress in signs, lung functioning, and immunological criterion in probiotic taking kids. Liu et al. (2016) described the effect of probiotics to improve the curative impact of allergen-definite immune treatment in asthma sufferers. The in vivo trial in rats having airways allergic inflammation when inoculated with Lactobacillus reuteri, improvement of inflammation and airway over sensitiveness in the probiotic receiving group of animals was observed (Forsythe et al. 2007; Karimi et al. 2009).

Moura et al. (2019) confirmed the role of probiotics as a complementary therapy for asthmatic children and teenagers. Furthermore, study is suggested to confirm the effectiveness of probiotics in asthma medication, particularly indiscriminate restricted experimental groundwork and ultimate cluster investigation, to assemble supplementary evidence and information on the promising expected advantage of probiotics for asthma sufferers.

There is a growing indication to put forward that each probiotic strain does not have a single exclusive mechanics of activity regardless of common taxonomical rank (Sanders et al. 2018).

The substantial cluster of proof is demonstrating that probiotics amend the type 1 helper T cell (Th1)/ type 2 helper T cell (Th2) (Th1/Th2) parity to forestall the improvement of inflammation infections such as allergy. The gut microbiota is having a vital role in re-establishing Th1/Th2 immunity.

The altered Th2 phenotype prompts an elevated number of IgE and hence activation of a mast cell, which will result in sensitivity to hypersensitivity disorders. The Th2- dominant phenotype of newborn displays higher receptiveness to hypersensitivity diseases. Amazingly, commensal colonization is contributed to this attribute, showing the important function of gut microflora. Commensals likewise assume a job in managing immune cell allocation. Therefore, susceptibility was accounted in adults following intense antibiotic course (Walker and Iyengar, 2015).

Another point of view of the perceptions is demonstrated in the “hygiene hypothesis.” This recommends less microbial contact through early stages due to the improved community cleanliness. It is one of the essential reasons for uplifted receptiveness to allergic hypersensitivity. Likewise, these studies set up the role of microflora to affect the allergy immune response (Sharma and Im, 2018).

13.3 The Rationale behind the Mechanism of Probiotics for Allergy

This new strategy is originated from diversified information revealing the pleiotropic impacts of probiotics that incorporate immunomodulation, re-establishment of intestinal imbalance of microbiota just as keeping up epithelium hindrance solidarity (Toh et al. 2012).

Inflammation is an elementary defense mechanism of the immune system against unknown immunogen; however, allergy is a host defensive immunity on recurring presentation to a particular unknown particle as an antigen, yet possibly harmful to the horde. Inflammation is a type of innate immune response against the foreign virulent particles associated with tissue rejuvenation. Probiotics presumably work as immunomodulators and actuator of human defense mechanism, that propose to impact disease seriousness and its rate. Probiotics therapy is established on the idea of typical fine microflora. The probiotic therapy is based on normalization of the properties of unbalanced indigenous microflora by specific strains of the healthy gut microflora. The advancement of mucosal and fundamental resilience depends on immunosuppressant action coordinated by T cells that assuage both Th1 and Th2 responses, mechanisms may incorporate regulation of the useful properties of the microbiota, epithelial cells, DC, and safe cell types.

The superior adhesion properties of probiotic facilitate the maintenance of the mucosal barrier and avoid the absorption of foreign particles and expansion of IgA mediated immune response. The proper development of bacterial colonization observed to downregulate the hypersensitivity reactions with alterations of the cytokine profile.

Figure 13.2 describes the foremost activities of probiotic to undertake the airway allergic condition. The probiotic presents in the standardization of the extended intestinal permeableness and distorted gut microbial bionomics, development of the intestinal immunological fence job, and improvement of the response of gut inflammation.

Fig. 13.2
figure 2

Mechanism of probiotic in allergic reaction

Full size image

The microbiome is fundamental for the advancement and learning of host immunity, mainly in the framework of allergic diseases. The use of probiotic influences the lung immunity followed by allergic airway infection due to augmentation of T regulatory-dependent mechanisms, however; whether this will impact the lung microbiota ruins to be determined. In reality, there is a need of elucidation of the mechanism of working of probiotic with assumed advantage for respiratory infections but there is paucity of data for airway microbiome composition.

13.3.1 Host Factors

The pathophysiology of susceptible illness, i. e. allergic disease results from an intricate series of actions including various ways of the natural immune response of innate and adaptive type. The allergic immune response involves stimulation of mast and basophil cells by IgE and succeeding allergen exposure resulted in allergic inflammation.

Host-associated factors can impact the working of the operation of the immune response in allergic hypersensitivity conditions and host and microorganisms communication (Laukens et al. 2016). Some vital characters are age, sex, host genetic structure, and microbiological status and can deviate in both human and animal investigation system (Laukens et al. 2016; Martín et al. 2017).

The pathogenic biofilm formation is the major host factor that leads to chronic infections. Biofilm formation is an accounted for about 65% and 80% of all microbial and chronic infections, respectively. Probiotic has the benefit as less cytotoxic than another quorum sensing (QS) suppressing agents and do not create strong pressure for resistance development like antibiotics. Hence probiotic could be an ideal alternative as an anti-virulent agent (Barzegari et al. 2020).

Probiotic prevents QS, biofilm formation, co-aggregation, and the survival of biofilm pathogens by interfering with biofilm formation and its quality. This is accomplished by decreasing the pH, competing for the adhesion sites with pathogens, and production of various antimicrobial agents like bacteriocin, hydrogen peroxide, and organic acids (Vuotto et al. 2014).

13.4 Allergy Prevention Studies with Probiotics

Current studies on meta-analysis of probiotics indicated a direct helpful impact on preliminary eczema impediment (Cuello-Garcia et al. 2015; Zuccotti et al. 2015), particularly to subsequent nativity to maternal and child to whom probiotics are administered. The probiotic will reduce the frequency of allergic sensitization with perinatal intercession, which is not at all the condition for pre- or postpartum cure only (Zhang et al. 2016). Nevertheless, the support of probiotic for the avoidance of allergic airway disease is rare. There is no noteworthy outcome on the breathless incident or asthma improvement (Azad et al. 2013).

Lactobacillus probiotics strain is found to modulate the pro-inflammatory cytokines such as TNF-α, IL- 6, IL 1–10, and IL 1β by activating the macrophage (Rocha-Ramírez et al. 2017).

Probiotic consumption could decrease the occurrence of respiratory tract infections. Aerosol delivery of probiotic diminishes tumor seeding in the lung and improves chemotherapy against exploratory metastases. Probiotic seems to defeat commensal microbes incited tolerance encouraging the maturation of resident antigen presenting cells.

The prevention or repairing of “leaky” epithelial barriers could serve for the pro-inflammatory response. The epithelium barrier is the primary defensive physical obstacle of the individual for the entry of detrimental particles like any pathogen, irritants, and allergic compounds (Koch and Nusrat, 2012).

Eventually, probiotics can influence the inflammatory response by contrasting the basis of pro-inflammatory motivation related with low-quality endotoxemia. Besides, probiotics and some of their emitted metabolic products can straightforwardly influence key pro-inflammatory pathways by acting as ligands for innate immune system receptors. Intercellular junctions, for instance, tight junctions (TJs), adherence junctions (AJs), and desmosomes contribute to the construction and continuation of the physical barrier.

The probiotics have an advantageous impact on epithelium barrier malfunction which is widely considered for the digestive tract. The example may include Lactobacillus plantarum MB452 which elevate the articulation of TJ-related genes by in vitro testing in well abdominal epithelial cells (IECs) (Anderson et al. 2010).

Related encouraging impacts were confirmed in case of probiotic strains such as Lactobacillus rhamnosus GG (Orlando et al., 2014), L. plantarum MB452 (Resta-Lenert and Barrett 2003), Streptococcus thermophiles ATCC19258, and the gram-negative probiotic strain Escherichia coli Nissle (Ukena et al., 2007; Zyrek et al. 2007) on abdominal epithelium barrier intactness and TJ expression. Moreover, certain Lactobacillus strains show the potential to elevate epithelium barrier integrity through the stabilization of AJs expression (Hummel et al. 2012).

In particular, to mention, the tested lactobacilli strain enhances the E-cadherin and b-catenin and diminishes the ample protein kinase C expression in T84 human abdominal epithelium cell line. Protein kinase C is the enzyme responsible for the disassembling of adherens junctions (AJs) (Hummel et al. 2012).

Several barrier-rebuilding characteristics of probiotics have also been verified in diverse in vivo models (Laval et al. 2015). There are at present scarce reports in the airways, relating the dictatorial characteristics of probiotics on the epithelium lining. The oral medication with L. rhamnosus CRL1505 could circumvent the polycytidylic acid [poly (I:C)]-induced improved permeable nature of the bronchoalveolar-capillarity barrier for in vivo experimentation, as find out by albumin levels in the lungs (Zelaya et al. 2014). This progress was associated to diminish the activation and synthesis of pro-inflammatory cells and cytokines in the lungs (Zelaya et al. 2014). Alike results were reported by nasally managed Lactococcus lactis NZ9000, which could neutralize S. pneumonia prompted permeable nature of lung tissue (Medina et al. 2008).

The in vitro studies reported dose reliant augmentation in epithelium obstacle functioning and reduction in epithelium permeability by prompting Calu-3 lung epithelium cells with the artificial bacterial lipopeptide Pam3CysSK4. This is caused due to improved articulation of the TJ proteins claudin-1 and ZO -1 and a lessen articulation of occluding.

Even though asthma is customarily viewed as a Th2-type inflammatory situation, it has been perceived as a clinically varied illness. The microflora composition of the gut and respiratory system is related to asthma incidents, as indicated by several reports. But it is not yet satisfactorily explained how disturbance of microbiota influences sensitivity to allergic asthma. It is projected that some metabolites formed during the fermentation of dietary fibers like short-chain fatty acids (SCFAs) by commensal suppress allergic airway responses (Trompette et al. 2014).

The Th2 response in the lungs is suppressed by higher serum SCFA, mainly propionate amending DC progenitors by G-protein fixed receptor in reliant way in the bone marrow. Butyrate is the foremost potent immune regulatory metabolite among the SCFAs. Histone deacetylase (HDA) inhibition is the mechanism of action for the butyrate and propionate function, with improvement in the acetylating status of histone in the Foxp3 site (Furusawa et al. 2013; Arpaia et al. 2013) and inducing tolerogenic DCs to augment Treg generation(Arpaia et al. 2013).

The Clostridiaceae family bacteria Lachnospiraceae and Ruminococcaceae are too recognized for the synthesis of SCFAs by fermented dietary fibers in the colon and thus sustaining epithelial integrity and homeostasis. But how this will helpful for humans, it needs to be confirmed by clinical trials (Sharma and Im, 2018).

13.5 Recent Advances: Clinical and In Vivo Status

In recent years, several experimental studies have investigated the capability of probiotic bacteria to improve the virulent traits of hypersensitivity disorders.

The animate models can be utilized in support of the probiotic impact and their systems of activity. This is found unrealistic in humans inferable from obscure dangers and moral concerns. The impact of such components should take into account during the experimental preliminary plan. The information exploration will encourage the advancement of superior probiotic intercessions and reinforce the proof for probiotic application in the prevention and cure of human beings ailment.

The effect of the human being genotype has likewise been proposed to assume a vital function in the result of probiotic medications, incorporating these acted with regard to allergic diseases. Individual hereditary contrasts and inclination towards inflammatory diseases ought to be thought about while surveying the impacts of probiotics in a clinical setting. The age of an individual and the influence of their gut microflora should take into consideration for the human being testing. All around elegant study and strong in vivo and in vitro investigation are thus essential to advance definite choice of probiotic species for anticipation and management of allergic illness (Spacova et al. 2018).

To date, in any case, a large portion of the study on probiotic has concentrated on the microflora only as opposed to the interaction between host and microbiota. Additionally, accessible information discards the significance of mycobiome and virome. The existing screening system is centered on the cytokine production efficiency and capability of microbes by using the cell lines or ex vivo isolated peripheral immune cells, even though they do not symbolize phenotypically to gut cells. It is a requirement to develop high-performance screening procedures to ensure the particularity and sufficiency of picked probiotics. The majority of the commercial probiotic preparations are a combination of different bacteria with distinct colony forming units (CFUs). The purpose is learning of the consumer about the period for the viability of a specific strain and number of bacteria in specific dose.

Consequently, experimental testing should be extended to incorporate distinct geological areas. Considering this, it is advantageous not to execute meta-analyses on shared records when diverse strains of bacteria were utilized since the impact can vacillate drastically between the strains. The use of probiotic strains ought not to be permitted except the security and effectors compounds of the probiotics are very well cleared (Sharma and Im, 2018).

13.6 Safety Considerations and Contraindications

Immunomodulatory action may rely upon strain-specific characters so ideal strain might be presented. Probiotics are viewed with a safe, rare short term side effect (Ciorba, 2012). Isolated instances of bacteremia or fungemia have been related to probiotics, though inhabitants information additionally shows that there is no across the board danger of these complications (Snydman, 2008). Microorganisms that are “generally regarded as safe” incorporate species of Lactobacillus and Bifidobacterium and definite yeast strains. Other bacteria, such as Enterococcus and Streptococcus strains, are not generally considered as safe, however they are utilized as probiotics (Snydman, 2008). Itself alert ought to be practiced in prescribing probiotics to these populaces. Studies examining probiotics are comparatively short in length, limiting the long term security information and the ability for the real unfavorable circumstance. To make the firm ends, an additional experimental trial examining the safety of probiotics must be led.

The inconsistent outcome may result from the contrast in the cogitation plan, readout, and patient understanding. One significant impediment for an absolute meta-analysis of probiotic studies is the implementation of diverse probiotic species and strains, mainly Bifidobacterium or Lactobacillus or combination of that (Zuccotti et al. 2015). The administered probiotic doses also change significantly among the study from 107 to 1010 or more (CFU)/day, and treatment duration may also vary from a while to quite a while (Zuccotti et al. 2015). Nonetheless, the outcome can vary among experimental set up in any event, though utilizing a similar probiotic strain and a similar direction routine because of the hidden possible significance of host-associated parameters. Along these lines, clinical studies heterogeneousness stays a significant hindrance to the conceptualization of validation-based rules on probiotic execution in allergic hypersensitivity (Forsberg et al. 2016).

Probiotics are susceptible to environmental surroundings such as moisture, heat, light, and oxygen. Customers should take precaution for storing probiotic containing product and adhered to the guidelines shown on the item label. One specific impediment restraint is the inability to indicate probiotic bacterial used for the study, depiction study duplication troublesome. Furthermore, numerous consumer diet complement exclude the particular bacterial strain or dosage of a probiotic on the mark, which makes it difficult for the drug specialist to advocate a product, in any event when a lesson is properly directed to deliver viable outcomes. Albeit numerous experimental testings bolster the protected use of probiotics, more exploration is expected to decide the long lasting safety of these items.

13.7 Future Directions

In current circumstance where the ebb and flow proof was created from hardly any preliminaries with serious extent of heterogeneity, routine utilization of probiotics as an added substance on treatment in subjects with unfavorably susceptible aviation route ailments cannot be suggested.

But the probiotic consumption emerges as a practicable way to diminish the frequency of respiratory tract diseases. Probiotics can affect together innate and adaptive immunity. Knowledge-based strategies supported with experimental data can be applied for successful clinical trials such as selection of optimal probiotic strain, microbe-derived compounds, the duration of regimens, administration forms, doses, and long follow-up time, as well as identification of potential early biomarkers of treatment efficacy. Recently scientist from Ireland, UK, and the USA propose the microbiome, live biotherapeutic product as a predictor of COVID-19 outcomes, for targeted immunomodulation in COVID-19 infection like prevention of virus attachment on host cells as well for prevention or treatment such as use of specific Lactobacillus strain as immunostimulatory adjuvant for intranasal vaccination, genetically engineered antigen producing organism. Consequently probiotics has great scope for the allergic airway infections which needs to determine.