Irmeli A. Penttila

Transforming Growth Factor-β Levels in Maternal Milk and Expression in Postnatal Rat Duodenum and Ileum

After birth, the gastrointestinal tract of the neonate is exposed to food and bacterial and environmental antigens. Maternal milk components may play a role in regulation of mucosal immune activity to luminal antigens. In this study we determine the ontogeny of transforming growth factor (TGF)-β1-producing cells in the rat pup small intestine and assess maternal milk concentrations of TGF-β. Intestinal tissue samples of duodenum and ileum were collected, processed, and stained for TGF-β1, and in situ hybridization for TGF-β1 mRNA was also performed on the duodenum. TGF-β levels in milk were assayed by ELISA. TGF-β2 levels in milk were high at d 6, and declined thereafter at d 10 and 19. TGF-β1 was not detected. In contrast, the cell number and intensity of staining of TGF-β1 peptide in the small intestine was low in 3- and 10-d-old rats and increased markedly by 19 d of life. In the duodenum mRNA levels mirrored this trend. TGF-β1 expression in the lamina propria was absent before d 19, and increased progressively over time. Maternal milk TGF-β2 levels are high in early milk and decrease during the weaning period. In contrast, endogenous TGF-β production in the small intestine increases during the weaning period.

Effects of transforming growth factor-beta and formula feeding on systemic immune responses to dietary beta-lactoglobulin in allergy-prone rats.

Early nutritional events have the potential to affect health outcomes in later life including the development of allergy. Food allergy is usually the first manifestation of allergy. Breast-feeding has been associated with a protective effect against the development of allergy, but the evidence is contradictory and the mechanisms involved are not clear. We hypothesize that milk cytokines, such as transforming growth factor β (TGF-β), play a role in regulating immune responses to dietary antigens. Using a rat pup model of gastrostomy feeding, the immune response profile, at weaning and post-weaning, of allergy-prone Brown Norway rats fed formula supplementation with TGF-β was assessed. We show that feeding formula to allergy-prone rat pups results in increased total IgE immunoglobulin, β-lactoglobulin (BLG) IgG1 antibody, and mucosal mast cell activation, as measured by serum rat mast cell protease II (RMCPII) levels in the gut. Supplementation of formula with physiological levels of TGF-β down-regulated the BLG IgG1 response as well as total IgE and mucosal mast cell activation. Supplementation of formula also resulted in an increase in Th1 cytokines, interleukin (IL)-18, IL-12p40, IL-12p35, and interferon gamma (IFN-γ) and an increase in IL-10. In conclusion, TGF-β supplementation of formula moved the immune response profile of allergy prone (Th2 type) rat pups toward a Th1 profile in the suckling period. Importantly, this immune profile persisted after weaning when TGF-β was no longer present in the diet.

Maternal milk regulation of cell infiltration and interleukin 18 in the intestine of suckling rat pups

Background and aims: In neonates the gastrointestinal tract is exposed to food and bacterial antigens at a time when the gut mucosal immune system has not developed the ability to induce oral tolerance. This increases the risk for an inappropriate immune response to oral antigens. Transforming growth factor β (TGF-β) is an immunoregulatory cytokine present in high concentration in maternal milk. Interleukin 18 (IL-18) is a cytokine that mediates early immune events, and drives T cell development. We assessed the role of TGF-β in mediating mucosal immune development and specifically the effect on endogenous IL-18. Methods: Rat pups were randomly assigned to the following groups, naturally suckled, maternal milk via cannula, and formula fed with and without physiological levels of TGF-β2. A comparison of the immune response profile was then carried out. Cytokine profiles, dendritic cell, intestinal mast cell, and eosinophil numbers were assessed. Results: We show that feeding formula deficient in TGF-β2 resulted in accumulated IL-18 protein release from intestinal epithelial cells and IL-18 mRNA up regulation. A proinflammatory cytokine profile resulted in the gut, along with increased numbers of activated dendritic cells, eosinophils, and mast cells. Supplementation of the formula with TGF-β2 down regulated the proinflammatory cytokine mRNA as well as the number of activated lymphocytes, eosinophils, mast cells, CD80, and CD86 positive dendritic cells. Conclusion: The data suggests an important role for maternal milk, in regulating immune responses after exposure to food antigens, which might otherwise induce deleterious immune responses in the intestine of suckling neonates. This regulation is potentially mediated by milk TGF-β2, as well as endogenous IL-18.

Localization of transforming growth factor-beta receptor types I, II, and III in the postnatal rat small intestine.

Transforming growth factor-β2 (TGF-β2) levels in rat milk are high in early lactation, whereas endogenous TGF-β1 expression in the neonatal gut increases toward midweaning. Three types of transmembrane TGF-β receptors have been identified in mammals. The receptor III (or betaglycan) binds and presents TGF-β1 or β2 to receptor II. Receptor I then interacts with receptor II, forming a signaling receptor complex, and propagates the signal. To determine whether TGF-β receptor expression in the gut is also developmentally regulated, the present study assessed ontogeny of TGF-β receptor expression in the postnatal rat small intestine. Jejunum and ileum tissues from rat pups at d 3, 10, 14, 21, and 28 of age were collected. Cryostat sections were stained with antibodies against TGF-β receptors I, II, and III, and various cell markers by immunofluorescence. In both regions, receptor I staining was seen on apical and basolateral membranes of the villus and crypt epithelium at all ages, and staining on the apical membrane increased with age; receptor II was predominantly expressed in the crypt, and staining on the villi appeared after d 10; receptor III was distributed throughout the mucosa at early ages but diminished from the epithelium postweaning by d 28. T cells, B cells, and dendritic cells in the lamina propria expressed TGF-β receptor III but lacked expression of receptor I and II. The pattern of TGF-β receptor expression changes with age in a manner that may reflect the change in ligand from TGF-β2 (milk-derived) to TGF-β1 (endogenously produced).

Immune modulation in suckling rat pups by a growth factor extract derived from milk whey.

Oral tolerance to foreign enteral antigens is not fully developed in early neonatal life. Epidemiological evidence supports a role for maternal milk in the development of immune responses, including oral tolerance. Formula fed infants have an increased susceptibility to food allergy and the later development of autoimmune disease. This may relate to the lack in infant formula of growth factors found in maternal milk. Bovine milk contains proteins, growth factors and cytokines. Various studies have outlined the immune modulating potential of bovine milk-derived products. Fractionated whey extracts have therapeutic potential in disease states where there is an excessive inflammatory reaction, and disease preventive potential for infants who are not breast-fed. We have shown that daily oral administration of a growth factor-enriched fraction from milk whey to naturally suckling rat pups between days 4-9 postnatal can down-regulate immune activation to a specific orally administered food antigen, ovalbumin, assessed by lymphocyte proliferation. In addition, non-specific down-regulation in the intestine was observed as assessed by the expression of MHC I. Treatment of rat pups with whey extract at the time of oral sensitisation to ovalbumin also resulted in an increased secretion of TGF-beta into the culture supernatant of spleen cells incubated with specific antigen. TGF-beta is an immuno-down-regulatory cytokine involved in tolerance induction. Immune modulation by extracts derived from milk whey could be of potential benefit for formula-fed and pre-term infants in reducing susceptibility to inappropriate activation to food antigens.

Heated Allergens and Induction of Tolerance in Food Allergic Children

Food allergies are one of the first manifestations of allergic disease and have been shown to significantly impact on general health perception, parental emotional distress and family activities. It is estimated that in the Western world, almost one in ten children have an IgE-mediated allergy. Cow’s milk and egg allergy are common childhood allergies. Until recently, children with food allergy were advised to avoid all dietary exposure to the allergen to which they were sensitive, in the thought that consumption would exacerbate their allergy. However, recent publications indicate that up to 70% of children with egg allergy can tolerate egg baked in a cake or muffin without apparent reaction. Likewise, up to 75% of children can tolerate baked goods containing cow’s milk, and these children demonstrate IgE and IgG4 profiles indicative of tolerance development. This article will review the current literature regarding the use of heated food allergens as immunotherapy for children with cow’s milk and egg allergy.

Allergenicity of pasteurized whole raw Hen's egg compared with fresh whole raw Hen's egg

Oral food challenges for diagnosis and management of egg allergy using fresh egg are common; however, to limit the risk of foodborne infection, many allergy units use pasteurized raw egg. Pasteurization and drying processes have the potential to affect the structure of egg proteins in egg powder and thus the allergenicity when compared to fresh egg. Our aim was to compare the binding of serum IgE from egg‐allergic children to in vitro digested and undigested pasteurized whole raw egg powder with unpasteurized fresh whole raw egg.

Wnt blockade with dickkopf reduces intestinal crypt fission and intestinal growth in infant rats.

Objectives: Intestinal crypt fission peaks during infancy. In human and experimental familial polyposis coli, increased crypt fission is due to activation of Wnt/&bgr;-catenin signalling, but the molecular basis of crypt fission during intestinal growth has not been examined. The aim of this project was to investigate whether crypt fission and intestinal growth are affected by experimental blockade of the Wnt/&bgr;-catenin signalling pathway. Methods: Hooded Wistar rats were given either the Wnt inhibitor, dickkopf (30 and 100 ng), daily or vehicle control intraperitoneally from days 11 to 15 and were killed at day 16. Intestinal morphometry was used to measure villous area, crypt area, percentage of crypt fission, and crypt mitotic count. Intestinal stem cells were assessed by expression of real time-polymerase chain reaction for Lgr5 (a stem cell marker), and the number of &bgr;-catenin–expressing crypts by immunostaining was determined after 100-ng dickkopf treatment. Results: Dickkopf at 30 and 100 ng/day reduced villous area to 71% (P = 0.013) and 29% (P < 0.0001), crypt area to 42% (P = 0.0026) and 30% (P = 0.0067), and crypt fission to 51% (P = 0.006) and 29% (P < 0.0001), respectively, of control values. Mitotic count per crypt did not change. Lgr5 RNA expression and the number of &bgr;-catenin–expressing crypts decreased in dickkopf-treated animals. Conclusions: We conclude that intestinal crypt fission during infancy is mediated by Wnt signalling. It is possible that local treatment with Wnt agonists could be used to increase intestinal growth.

Early Oral Ovalbumin Exposure during Maternal Milk Feeding Prevents Spontaneous Allergic Sensitization in Allergy-Prone Rat Pups

There are conflicting data to support the practice of delaying the introduction of allergenic foods into the infant diet to prevent allergy development. This study investigated immune response development after early oral egg antigen (Ovalbumin; OVA) exposure in a rat pup model. Brown Norway (BN) rat pups were randomly allocated into groups: dam reared (DR), DR pups challenged daily (days 4–13) with oral OVA (DR + OVAc), DR pups challenged intermittently (on day 4, 10, 12, and 13) with oral OVA (DR + OVAi), formula-fed pups (FF), and FF pups challenged daily with oral OVA (FF + OVA). Immune parameters assessed included OVA-specific serum IgE, IgG1, and IgA. Ileal and splenic messenger ribonucleic acid (mRNA) expression of transforming growth factor-beta (TGF-β1), mothers against decapentaplegic (Smad) 2/4/7, and forkhead box P3 (Foxp3) were determined. Ileum was stained for TGF-β1 and Smad4. Results. Feeding OVA daily to DR pups maintained systemic and local gut antibody and immunoregulatory marker mRNA responses. Systemic TGF-β1 was lower in DR + OVAi pups compared to DR and DR + OVAc pups. Feeding OVA to FF pups resulted in significantly greater OVA-specific IgE and IgG1, and lower IgA and TGF-β1 and Smad expression compared to DR pups. Conclusions. Early daily OVA exposure in the presence of maternal milk maintains immune markers associated with a regulated immune response, preventing early allergic sensitization.

Allergenicity of pasteurised whole raw egg powder compared with fresh whole raw egg

Background: Antibodies of the IgE isotype and their recognition of allergens at the initiation of allergic response are crucial components of allergic reactions, with influence on the severity of the disease. Despite this, detailed information on the molecular nature of IgE-allergen interactions is still lacking for most important allergens. Method: IgE-derived antibody fragments specific for the major birch pollen allergen Bet v 1 were isolated from combinatorial libraries derived from the IgE-repertoires of nasal tissue of allergic donors. Their interactions with Bet v 1 were characterised using immunological assays. The structure of one of the IgE in single chain fragment variable (scFv) format was solved using X-ray crystallography. Results: We isolated four novel Bet v 1-specific IgE-derived antibody fragments with genetic origin in the IGHV5 germline gene, suggested to be overrepresented in some IgE repertoires. We show that that such antibodies, despite their limited diversity, are able to fulfill the basic criteria for FceRI cross-linkage by targeting two nonoverlapping epitopes. These previously undescribed IgE-reactive epitopes were further defined and a molecular basis for differential recognition of Bet v 1 isoforms and homologous allergens of the PR-10 family was identified by pinpointing important single amino acid residues within one of the epitopes. Further, we present the first highresolution structure of a human allergenspecific IgE in the scFv format, a structure that demonstrates that a human allergenspecific antigen binding site may display a protruding CDRH3. Conclusion: We here demonstrate the potential of local IgE repertoires with limited diversity in their genetic origin to fulfill the basic criteria for initiation of allergic responses. Further, the non-planar epitope targeted by MO418 and its protruding CDRH3 contrasts previous findings, suggesting IgE to favour planar epitopes, calling for further investigations of the nature of such epitopes.In recent times, allergy has become a financial, physical and psychological burden to the society as a whole. Allergic reactions can result in life-threatening situations causing morbidity and high economic cost. Therefore, more effective reagents are needed for allergy treatment. Omega-6 fatty acids have gained attention in allergic studies mainly due to their inflammatory properties. Literature suggests that a causal relationship exists between the intake of omega-6 fatty acids such as DPA and AA and atopic individuals suffering from allergies. In an allergic cascade, cytokines IL-4 and IL-13 bind to IL-4 receptor (IL-4R), which activates the STAT6 phosphorylation pathway leading to gene activation of allergen-specific IgE production by B cells. Consequently, IgE production leads to clinical symptoms of allergy. The overall aim of this study is to characterise DPA and AA and their effects on IgE production.Food allergy has continued to rise over the past few decades. Theincreasing occurrence of sensitivity to certain foods remains to be identified, and the allergen-epithelial interaction in particular remains elusive. Peanuts in particular are still one of the highest contributors of anaphylaxis after ingestion of a food allergen. Previous findings by our research group observed that peanut allergens were able to cross the Caco-2 cell culture model of the intestinal epithelium. Specifically, the major peanut allergens Ara h 1, Ara h 2 and Ara h 3, as well as Ara h 6. The direction of this research has deepened into identifying the mechanism by which the Caco-2 monolayers uptake peanut allergens, specifically by endocytosis. Here, we aim to further our understanding about the pathway from allergen to allergy.