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This presentation aims at getting allergists acquainted with the concept of probiotics and

their use in clinical practice, based on the evidences available to date.

Dr. Pedro Ojeda received honoraria from Allergy Therapeutics to give this

talk.

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This slide stands out the National Microbiome Initiative promoted and

endorsed by the White House in which $400 Million will be invested in

research on the human microbiome, highlighting the importance that the

microbiome is acquiring in science and therefore scientists and particularly

physicians cannot remain unaware of this emerging field and the world of

probiotics. They should at least be knowledgeable and then decide by

themselves whether they embrace it or not.

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As an allergist, for me, the fields of probiotics and immunotherapy share

important periods and concepts.

Dr. Élie Metchnikoff may be regarded as one of the fathers of Probiotics. In

1907 he published “The prolongation of life” in which he stated that the

putrefaction of food in the gut could be the origin of toxins that could shorten

individual’s life. He observed that Bulgarian people lived longer than others

and related this fact to their consumption of sour milk, as a source of

beneficial bacteria. This book may be considered the starting point of

probiotics science.

Not much later, in 1911, Leonard Noon and John Freeman published their

pivotal study “Prophylactic inoculation against hay fever”, in which they

established the basis for current allergen immunotherapy, although the concept

at that time was that hey fever was caused by a toxin and this inoculation

consisted of an “anti-toxin”.

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The 1960´s were another important period for both fields. In 1965 Dr. Daniel

Lilly and Dr. Rosalie Stillwell coined the term probiotic as a growth-

promoting factors produced by microorganisms to facilitate the proliferation

of specific bacteria in the gut.

In 1967, three independent research groups got to the discovery of the

immunoglobulin E, one of the key elements in allergic reactions.

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The end of the 20th and beginning of the 21st centuries are important dates as

well. In 1998, in a worldwide referenced position paper, the WHO endorsed

allergen immunotherapy and allergen avoidance as the only treatments that

may have an impact on the natural course of allergic diseases, by contrast with

pharmacological therapies. Three years later, the WHO and FAO set up an

expert panel to discuss for the first time on probiotics and how to better

scientifically assess their effects on human health.

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Prebiotics are essentially sugars; most of them are inulin-type fructans or inulin oligo or

polymers, galactans or mixtures of fructans and galactans; new prebiotics are being investigated.

Prebiotics are mainly used to feed the bacteria included in a probiotic product.

In some patients with intestinal bacterial overgrowth (SIBO), prebiotics may be badly

tolerated so a prebiotic-free product may be selected to treat them.

It is important to know that prebiotics have biological effects by themselves,

including immune regulation functions.

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Synbiotics are just a mixture of prebiotics and probiotics.

Again the parallelism with allergen immunotherapy: In the same way it is

important the quality of the allergenic extract as well as the kind of adjuvant

used in an allergy vaccine, it is important to kwon the genus and strain of the

probiotics, and the type of prebiotic included in this kind of products.

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The study of Hunt et al published in 1978 in the NEJM clearly showed that

immunotherapy with whole body hymenoptera extract was no better, even

worse, than placebo to treat hymenoptera sting allergy: the rate of reactors

after hymenoptera sting following a course of immunotherapy was very

similar in the group of patients having received whole body extract and

placebo. However, the rate of reactors was 10 times lower in the patients

receiving pure hymenoptera venom extract. Since then, allergy vaccines for

hymenoptera allergy are only produced from pure hymenoptera venom, and

the cure rate in theses patients may be as high as 98% for wasp allergy.

This is a clear example of the importance of conducting properly designed

studies to show the efficacy of a particular treatment in a specific disease.

Therefore, if we want to assess the efficacy and safety of probiotics-containing

products, properly designed trials must be conducted.

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These are the results of a PubMed search looking for “probiotics” and

“human”, and filtering by any kind of article, clinical trials, or meta-analysis.

Although publications on probiotics started already in the 1960s, it was not

until the 1980s that the scientific production started to blossom. Similarly, the

publication of clinical trials on probiotics in humans began to increase by the

end of the 20th Century, and meta-analyses began to be conducted by the mid-

first decade of the 21st Century.

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However, probiotics are living organisms and as proposed in this publication,

several factors of the host and the product and production process have to be

taken into account when carrying out clinical trials.

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In 2002, the FAO and the WHO put together a Working Group to establish the

guidelines for the evaluation of probiotics in foods.

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The steps included in these guidelines are summarized in this slide.

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However, in 2008, Hoffman et al published in Clinical Infectious Diseases the

main needs that still have to be met in order to properly establish the efficacy

of probiotics in human health and diseases. One of the key points is the

importance of properly differentiating the characteristics and effects that may

be generalized to a genus or species and which other are specific of a strain.

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In 2010, Dr. Gregor Reid, who was the chairman of the 2001 WHO/FAO

Expert Panel on probiotics, criticized the policies of both the FDA and the

EFSA about the evaluation of probiotic-containing products, setting up

excessively stringent standards for the authorization of these products, and

proposed, in this publication, a new way of evaluating probiotics.

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To date, the FDA requires the opening of a New Investigational Drug (NID)

file for every product for use in the diagnosis, cure, mitigation, treatment or

prevention of any disease; in this example, the product Polagen by Allergy

Therapeutics, sold in Spain as a “synbiotic food supplement, based on

probiotics, indicated for the treatment of grass pollen-induced allergic rhinitis”

should undergo an NID process of evaluation in order to obtain the license to

be sold in the US market.

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The implications of an NID file are shown in this slide.

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A group of experts put together by the School of Law of the University of

Maryland published a report with recommendations for change in the

assessment process and regulation of probiotics. Among other proposals, the

considered the creation of a new category less regulated than drugs and

medical devices for probiotics.

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In the EU, the Regulation No. 1924/2006 establishes the rules dictating the

labeling and health claims of functional foods, including probiotics and

probiotic-containing foods. It is clearly established that sound scientific works

must endorsed the health claims of these products.

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The rationale for the use of probiotics in allergic diseases derives from the

basic and experimental studies in animals that have shown a potential to

down-regulate Th2-type (pro-allergenic) immune responses and promote Th1-

type responses and the population of regulatory T lymphocytes, along with

some other immunological and non-immunological, but important effects such

as increased mucosal IgA, anti-inflammatory effects and improvement of the

epithelial barrier that may be paramount for allergen exclusion at the skin and

intestinal barriers.

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One of the first RCT on the use of probiotics for the prevention of allergic

diseases using L. reuteri vs placebo during the last month in utero and the first

year of life failed to demonstrate an effect on the prevention of allergic

sensitization or any other allergic disease up to 7 years of follow-up.

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Some other trials and meta-analyses have been performed later on and I focus

on the latest two published, respectively in the Journal of Allergy and Clinical

Immunology (2015) and Allergy (2015). In the first one, it was shown that

probiotics reduced the risk of eczema when introduced prenatally, during

breast-feeding and when given to infants during the first year of live; however,

the certainty of this results was low.

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The second meta-analysis again showed this protective effect on the

prevention of atopic eczema, specially when mixtures of probiotics

(lactobacilli and bifidobacteria) were given, but no effect was shown on the

prevention of allergic rhinoconjunctivitis or asthma.

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However, letters to the editor were written criticizing both meta-analyses: in

the first case, because of pooling data from studies using different species and

strains of probiotics, arguing that studies and meta-analysis should be done

with specific strains for particular health effects; the authors argued it would

be the same as carrying out a meta-analysis to show whether any kind of

antibiotic is useful to treat pneumonia.

In the second case, the authors disagreeing state that the studies included in the

meta-analysis are the same but taken at different periods of their lives and

published in different studies and, again, the argue against the heterogeneity of

the species of probiotics used in the different studies analyzed.

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This other meta-analysis has shown, however, a protective effect on

sensitization (positive skin prick tests) to inhalant and food allergens when

probiotics are administered prenatally to the mother and postnatally to the

infants.

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Regarding the treatment (not prevention) of atopic eczema the evidence shows

that the use of probiotics may help improve the course of the disease both in

children and adults with moderate to severe disease. The use of probiotic

mixtures, and particularly Lactobacilli showed the greatest benefit.

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Two meta-analyses have shown that probiotic used pre-and co-seasonally for

allergic rhinitis helps reducing the symptoms score and improve quality of life

results.

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Besides, the second one have shown immunological changes favoring the

skewing of the immunological response towards a Th1 response. Moreover, it

seems that Lactobacillus paracasei strain 33 yields the more consistent

benefits.

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Several meta-analyses have been carried out and none of them has shown a

benefit of probiotics in the prevention or treatment of asthma or wheezing, so

there is no evidence supporting their use for this condition.

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However, a couple of meta-analyses have shown a reduction of upper and

lower respiratory infections in children, and less days loss of school

attendance with the use of probiotics. So, in children particularly prone to

respiratory infections there is a basis for the use of probiotics to help them

improve their condition.

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The different meta-analyses have failed to show a beneficial effect of the use

of probiotics for the prevention of food allergies and the latest EAACI

guidelines on food allergy and anaphylaxis do not recommend their use for

this purpose; however, as mentioned a few slides before, one meta-analysis

have shown a reduction in the rate of positive SPT with food allergens.

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Notwithstanding, there is one study showing that the addition of Lactobacillus

rhamnosus (LGG) to an extensive hydrosilate of cow’s milk proteins

considerably and significantly improves the rate of natural acquisition of

cow’s milk tolerance at one year of age in both milk allergic and intolerant

infants.

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Another study has shown that the combination of probiotics (LGG) to oral

tolerance induction therapy with peanut clearly improves the tolerance to this

food, even when interrupting peanut ingestion for 4-5 weeks after acquisition

of tolerance, as compared to a control group of peanut-allergic children treated

with sham OTI+placebo. In my opinion, the design could have been better if

two groups of peanut-OTI treated patients were compared, one using probiotic

and the other group using placebo.

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This is a very rapidly changing area of research and this is reflected in the

recommendations of the World Allergy Organization (WAO) since in 2012 in

its position paper this Institution did not recommended the use of probiotics in

allergy clinical practice given the lack of sufficient evidence and three years

later, this same scientific society did recommend the use of probiotics pre and

postnatally, and in breastfeeding mothers for the prevention of atopic eczema

in high risk infants (those with mother and/or father and/or siblings) with

allergic diseases.

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