In a recent paper, Perkin et al. have investigated the role of different aspects of the farming lifestyle and particularly dietary factors in the development of allergic disorders in childhood (1). In the study farmers’ children have a reduced prevalence of current asthma and of seasonal allergic rhinitis symptoms. Among all the different considered environmental factors, only the current unpasteurized milk consumption was associated with less atopy and less eczema, independently by the farming status. This consistent protective effect was not apparent for any other food assessed by food-frequency questionnaire. The effect of unpasteurized milk consumption was associated with other objective measures such as skin prick test wheal size, serum total IgE levels, and interferon-γ production in stimulated whole-blood assay, leading authors to suggest that the protective effect was a genuine phenomenon (1). Another study has recently confirmed that farm milk consumption ever in life is significantly and inversely associated with asthma, rhinitis, and sensitization to allergens (2). Of particular importance in this last study is the consistency of the same findings across children from farming, rural non-farming, anthroposophic, and urban environment. This indicates that farm milk consumption since the first year of life may represent a route of exposure that is independent of concomitant exposure to microbial compounds present in animal sheds and farm homes (2). In both papers, authors speculate about the components of the farm milk responsible for the observed protective effect, focusing in particular on the different levels or different composition of pathogenic and non-pathogenic microbes compared with milk after pasteurization (1, 2). In fact unpasteurized milk is rich in a variety of gram-negative species and of their lipopolysaccharides, which could influence from early age the developing immune system (3). Unpasteurized milk can also contain lactobacilli that could have a protective effect for eczema (4). However, it can be argued that also other compounds, different from microbes, and specifically fatty acids and/or cytokines may play a role for the effect of unpasteurized milk. Considering breast milk, a variety of different factors have been associated to the effects on the children’s immunity and development of allergic diseases. Oddy et al. showed that fatty acid profiles (increased ratio of n6:n3 fatty acids) may be associated with non-atopic eczema in infants at 6 months (5). Different cytokines are also detectable in breast milk (IL-4, IL-5, IL-6, IL-10, IL-13, IFNγ, and transforming growth factor-β1 [TGF-β]), which seem to vary in concentration according to the allergic status of the mother and to the duration of lactation (6). Indeed, epidemiologic studies focused on the role of TGF-β1 in breast milk to provide protection against allergic diseases in infancy (7). TGF-β is a multifunctional cytokine involved in cellular proliferation, differentiation, extracellular matrix regulation and survival that is considered to be primarily involved in the development of the infant immune responses (8). We have recently observed that in breastfeeding mothers TGF-β1 was significantly higher in colostrum compared with mature milk, and it was significantly lower in atopic vs. non-atopic mothers (9). Furthermore, in a recent animal model study, it has been demonstrated that orally administered TGF-β1 retains biological activity in the intestinal mucosa and enhances the induction of oral tolerance to a high-dose antigen (10).
Therefore, aim of the present study was to verify the presence and to quantify the levels of TGF-β1 in different treated cow’s milks to add further informations on the cow’s milk composition in relation to development of allergic diseases.