Bibliographic updates

The Monthly choice - April 2016

Claude MOLINA & Jacques GAYRAUD

1. Occupational asthma: Predictive value of métacholine bronchial challenge.
2. Lidocaïne and severe Atopic Dermatitis
3. Avoidance on peanut allergy in infants after early consumption
4. Introduction of Allergenic Foods in breast-fed infants and Prevalence of Allergy.
5. Prevention of food allergy in Infancy

1. Occupational Asthma: (OA) Predictive value of methacholine bronchial challenge
(J.A.Pralong JACI 2016 137 2 412-416)
The Canadian authors sought to evaluate the sensitivity, specificity, positive and negative predictive value of methacholine challenge at baseline of the specific inhalation test:“gold standard” of the diagnosis. A database was used to review 1012 cases suspected of OA between 1983 and 2011 and submitted to specific and nonspecific challenges at the work place and outside work.
When considering all subjects tested at work (479 cases) it appears that the sensitivity value is 98,1% and the negative predictive value 97,7%.
So even in doubtful cases, a negative methacholine challenge in patients still exposed to causative agent, makes the diagnosis very unlikely

2. Lidocaïne and Severe Atopic Dermatitis
(H.Li et al JACI 2016 Feb 137 2 613-617)
Lidocaïne (L) is a widely used short-acting local anesthetic which, in previous studies has demonstrated, by aerosols in patients with severe asthma, attenuation of bronchoconstriction. Because of the similarity of allergic diseases, L was used by Chinese authors in the treatment of severe AD in young patients and in murine models sensitized by ovalbumin. 20 patients were administered 3mg/kg day L. via a slow intravenous drip, with a good tolerance, improvement of skin inflammation and clinical remission. Skin biopsies and immune studies uncovered the molecular mechanism of L. in T.reg regulation, with promotion of Fox P3 transcription by activating TGF β -induced Smad3 phosphorylation. Moreover L. improved the TH1/TH2 cell et 17A/17 E cytokine imbalance, in both patients with AD and murine models, exerting its regulatory effects on immune cells.

3. Avoidance on peanut allergy in infants after early consumption
(G.Du Toit et al : NEJM 2016 March 4 On line first)
In a previous randomized trial in more than 600 infants at high risk for allergy, the early introduction of peanuts was shown to prevent peanut allergy. At the end of the primary trial, the authors instructed participants to avoid peanuts for 12 months; then 2 groups are followed until 5 years of age; the first group with exclusive avoidance and the 2nd group who carry on peanut consumption. At 72 months, peanut allergy was most prevalent in the peanut avoidance group than among those in the peanut consumption group. So it appears that a 12 months period of peanut avoidance was not associated with an increase of peanut allergy. Moreover the participants of this group have a higher level of IgG4, high level of Ara2 and higher IgG4/IgE ratio.
So the tolerance went on for a few years after early consumption.

4. Introduction of Allergenic Foods in breast-fed infants and Prevalence of Allergy
M.R.Perkin et al : NEJM 4 March 2016
The British authors sought to evaluate whether early introduction of allergenic foods in the diet of breast-fed infants would protect them against food allergy. They recruited from the general population 1303 infants, exclusively breast-fed, who were 3 months of age, and randomly assigned them to : either early introduction of six allergenic foods : peanut, cooked egg, cow’s milk, sesame, white fish , wheat, or carry on exclusive breast-feeding to 6 months of age. The primary outcome being food allergy to one or more of the six foods between 1 and 3 years of age. The results were disappointing: 7.2% of Food allergy in the standard group, 5.6% in the early introduction group. However a per-protocol analysis showed a lower prevalence of peanut and egg allergy, maybe dose-dependent.
In conclusion, this trial, which was totally safe, did not show the efficacy of early introduction of multiple allergenic foods.

5. Prevention of food allergy in Infancy
G.W.K.Wang NEJM 2016 Editorial On line first
The age at which allergenic foods should be introduced into the diet of breast-fed infants is uncertain. Classical recommendation for decades urged parents to avoid early exposure which risk allergic sensitization.
The first compelling trial of British pediatricians: Learning Early about Peanut Allergy (LEAP) showing that the early consumption in infants, on the contrary, decreased the risk of peanut allergy, turned this idea on its head and provided new guidance as primary preventive strategy. But what about other common foods such milk, egg and fish?
The second important trial (Enquiry about Tolerance - EAT) attempted to answer these questions in designing a protocol with early introduction of six foods in exclusively breast fed infants from the general population and starting at 3 months until 3 years of age. The first analysis (intention to treat) and a such demanding protocol in real life, makes the early feeding approach ineffective. However we know that administering these foods is safe and at a population level, evidence is building that early rather delayed consumption is likely to be more beneficial as prevention strategy.
So, in conclusion, the author gives with humor this advice:” Feed your children and hope that they will EAT”.

Comments and questions may be sent to:

Claude Molina
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Jacques Gayraud
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Last updated 27 December 2016