Let us know first what is’ PROBIOTICS’. In the term probiotics ,the word ‘pro’ means “for” and the word ‘biotic’ means “life”. The exact definition of probiotics is that they are the bacteria that are helpful to keep our gut healthy and when it gets disrupted through long term antibiotic use or gastrointestinal diseases probiotics restore the balance of bacteria in gut. These different strains of microorganisms has huge range in clinical and immunologic capacities to modify the intestinal microbial population that can benefit the host . From the past 2-3 decades ,the prevalence of allergic diseases like asthma ,allergic rhinitis, dermatitis ,etc. has increased sharply and now they are the most chronic diseases among the world. Research in this area shows that ‘Probiotics’ have crucial role in preventing the allergic diseases ,although further evidence is needed to determine its efficacy .In this article we will discuss what is the role of probiotics in preventing allergies? What are its benefits? How do probiotics work?
Keywords: probiotics, allergic rhinitis, dermatitis , antibiotic , gastrointestinal ,gut.
The rapid increase in prevalence of allergic diseases and high burden require new strategies for prevention, diagnosis and treatment. Day by Day this disease is most concerning around the world and need to give importance to get rid of it .As shown in graph ,we conclude that majority of the population worldwide is suffering from different types of diseases that continue to rise year after year
The allergic diseases result from undergoing failure of the immune system due to decreased exposure to microbes. In addition to environmental factors ,intestinal flora may be a contributor to allergic diseases. These allergic response are arise due to absence of microbial exposure while the immune system is developing .The gut microbiota is major source of microbial exposure. Exposure to microbial flora early in life makes a change in TH1/TH2 balance . Microbiota is an increasing body , playing a crucial role in shaping the normal development and maturation of the immune system . All the allergies , risk of atopy, asthma ,antibiotic use etc. act on microbiota. In all the studies it was found that probiotics have a crucial role in preventing allergies .According to WHO , probiotics are defined as the live organism conferring the health benefits to the host . Probiotics mechanisms of action include enhanced mucosal barrier function , modulation of innate and adaptive immune system , regulation of enteric and nervous system .The strains most generally used as probiotics belong to genera ‘Bifidobacterium and lactobacillus’ .They are provided as food supplements They also play non immune , protective roles by directly blocking intestinal pathogenic microbes and enhancing mucosal integrity through epithelial cell stimulation .
In this article ,we review the evidence supporting the mechanism of action of probiotics based on this hypothesis .We summarize the recent basic research to elucidate the mechanism of probiotics and their effects on allergic diseases.
MECHANISM OF PROBIOTICS ON ALLERGIC DISEASES
The United nation food and agriculture organization and WHO administered the health benefits of probiotics to the host .
1. Allergic diseases are associated with TH2 response with a shift of TH1/TH2 cytokine balance. This leads to activation of TH2 cytokine and production of interleukin 4 , 5 , 13 and IGE .
2.Probiotics inhibit allergic diseases by suppressing TH2 response and also the representative cytokine by TH2 cell .
3. Probiotics alters the gut microenvironment by promoting change in local microflora and also in cytokine secretion leading to activation of Th 1 response .The resulting activation of Th1 response suppresses Th2 response .
Another mechanism include the selected strain of probiotics provides maturational signal for gut associated lymphoid tissue ,development of tolerogenic dendritic and differentiation of regulatory T cell .This will improve barrier function and reduce attack of allergic reactions. Also the stimulation of toll-like receptors, which leads to production of mediators like IL6 and then IgA secretion .The production of IgA leads to exclusion of antigens from intestinal mucosa
Probiotics modulate the immune system and prevent allergies .In short probiotics have various mechanisms such as increased local IgA production, tolerance induction , antigen penetration ,stimulation of Th1 response to allergens ,production of Treg are the systemic effects of probiotics
EVIDENCE ON PREVENTION OF ASTHMA AND FOOD ALLERGY BY PROBIOTICS
1 Asthma - In today's generation asthma is the biggest problem due to increasing pollution . Numerous studies exist that try to indicate the effectiveness of probiotics supplementation in the treatment or prevention of asthma .The most recent was conducted by Giovanini and colleagues by using fermented milk containing lactobacillus casei and studying its effects on asthma patients . 187 children's were included in the study .At the end of 12 month trial investigators conclude that the Lactobacillus casei benefits children with rhinitis .Still there is insufficient data to recommend probiotics for prevention of asthma . Probiotics prevented asthma-like symptoms in infants . Pulmonary function etc. Despite numerous studies, effects of probiotics have been impeded by limitations .To overcome these limitations ,further studies are needed .
2 Food allergy - Food allergy is increasing at an alarming rate and is a major public health concern .As we know gut microbiota is important in maintaining immune functions . In a review involving 1,549 infants ,Osborn and Sinn stated the benefits of probiotics in reducing food hypersensitivity .In probiotic strains they show the ability to restore intestinal microbic equilibrium and modulate activation of the immune system . One example of probiotics is that Lactobacillus rhamnosus can induce tolerance among infants with cow's milk allergy. Probiotics can also treat food allergy by maintaining the intestinal epithelial barrier integrity, suppressing inflammatory response of intestine,inducing IgA production etc. Due to imprecise results there is a lot of uncertainty regarding use of probiotics for relieving symptoms of food allergy .That's why there is a need for a lot of research and study on probiotics and its treatment towards prevention of food allergy .
In the above article we look at the properties of probiotics and its mechanism in treatment and prevention of allergies specially we look into food allergy and asthma .The interaction between probiotics and immune system seems to be beneficial for preventing allergic disease but the studies to date are are not sufficient as well as not conclusive .Further studies will be important to refine the current research and knowledge base for potential use of probiotics in allergy treatment Future research on this concept helps to improve efficacy of probiotics for prevention and treatment of diseases . More evidence is needed for confirmation of particular species having antiallergic potential .
Department of biochemistry and biotechnology
St. Xavier’s college ,Ahmedabad
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