The role and potential use of oral transforming growth factor-beta in the prevention of infant allergy

Oral Tolerance Induction to Newly Introduced Allergen is Favored by a Transforming Growth Factor-β-Enriched Formula

Food allergies have become a major healthcare concern, hence preventive efforts to ensure oral tolerance induction to newly introduced antigens are particularly relevant. Given that transforming growth factor-β (TGF-β) plays a key role in immune tolerance, we tested whether an infant formula enriched with TGF-β would improve oral tolerance induction. A partially hydrolyzed whey protein-based formula was enriched with cow's-milk-derived TGF-β (TGF-β-enriched formula) by adding a specific whey protein isolate (WPI). The manufacturing process was optimized to achieve a concentration of TGF-β within the range of human breast milk concentrations. Protection from allergic sensitization and immune response was assessed in a mouse model. Adult mice received the TGF-β-enriched formula, a control non-enriched formula, or water ad libitum for 13 days before sensitization and suboptimal tolerization to ovalbumin (OVA). When compared to non-tolerized mice, suboptimally-tolerized mice supplemented with the TGF-β-enriched formula showed significantly lower levels of total immunoglobulin-E (IgE) and OVA-specific (IgG1). Mouse mast-cell protease-1 (mMCP-1) and cytokine levels were also significantly decreased in suboptimally-tolerized mice fed the TGF-β-enriched formula. In conclusion, oral supplementation with cow's-milk-derived TGF-β decreased allergic responses to newly introduced allergens and thus reduced the risk of developing food allergy.

Genetic evidence for the role of transforming growth factor-β in atopic phenotypes

New evidence in humans and mice supports a role for transforming growth factor-β (TGF-β) in the initiation and effector phases of allergic disease, as well as in consequent tissue dysfunction. This pleiotropic cytokine can affect T cell activation and differentiation and B cell immunoglobulin class switching following initial encounter with an allergen. TGF-β can also act on mast cells during an acute allergic episode to modulate the strength of the response, in addition to driving tissue remodeling following damage caused by an allergic attack. Accordingly, genetic disorders leading to altered TGF-β signaling can result in increased rates of allergic disease.

Atopic dermatitis prevention in children following maternal probiotic supplementation does not appear to be mediated by breast milk TSLP or TGF-β

Background

The Probiotics in Prevention of Allergy among Children in Trondheim (ProPACT) study, a randomised, placebo controlled trial, demonstrated that maternal supplementation with probiotic milk reduced the incidence of atopic dermatitis (AD) in infancy. The mechanisms behind this effect are incompletely understood and breast milk cytokines have been postulated as possible mediating factors. In this study we aimed to assess whether breast milk TLSP and TGF-β are affected by a maternal probiotic supplementation regime, and their contribution to the preventive effect of this regime on AD in the offspring.

Methods

TSLP and TGF-β isoforms (TGF-β₁, TGF-β₂ and TGF-β₃) were measured using ELISA and multiplex assays, respectively, in breast milk samples collected at 10 days and 3 months postpartum from women participating in the ProPACT trial (n = 259). The natural indirect and direct effects of maternal probiotics on AD, due to changes in breast milk cytokines, were estimated using causal mediation techniques.

Results

Probiotic supplementation tend to lead to high levels of breast milk TSLP at 10 days postpartum (p = 0.062), but this change did not contribute to the prevention of AD according to the mediation analysis. Probiotics had no apparent effect on TSLP at 3 months or TGF-βs at either time points. Thus, these are unlikely to be mediators of the effect of maternal probiotics on AD in offspring.

Conclusions

Whilst maternal probiotic supplementation resulted in higher breast milk concentrations of TLSP at 10 days postpartum, this does not appear to be a mechanism for prevention of AD by maternal probiotics.

Trial registration The original trial protocol is registered in ClinicalTrials.gov (identifier NCT00159523)