Oral administration of bovine whey proteins to mice elicits opposing immunoregulatory responses and is adjuvant dependent

Oral tolerance: an updated review

Oral tolerance (OT) has classically been defined as the specific suppression of cellular and/or humoral immune responses to an antigen by prior administration of the antigen through the oral route. Multiple mechanisms have been proposed to explain the induction of OT including T cell clonal depletion and anergy when high doses of antigens are fed, and regulatory T (Treg) cell generation following oral administration of low and repeated doses of antigens. Oral antigen administration suppresses the immune response in several animal models of autoimmune disease, including experimental autoimmune encephalomyelitis, uveitis, thyroiditis, myasthenia, arthritis and diabetes, but also non-autoimmune inflammatory conditions such as asthma, atherosclerosis, graft rejection, allergy and stroke. However, human trials have given mixed results and a great deal remains to be learned about the mechanisms of OT before it can be successfully applied to people. One of the possible mechanisms relates to the gut microbiota and in this review, we will explore the cellular components involved in the induction of OT and the role of the gut microbiota in contributing to OT development.

Lifelong Maintenance of Oral Tolerance and Immunity Profiles in Mice Depends on Early Exposure to Antigen

Oral tolerance is defined as a state of systemic hyporesponsiveness to an antigen that has been previously administered by the oral route. Many factors affect oral tolerance induction; some of them related to antigen, and some related to the animal. The age of the animal is one of the most important factors that affect oral tolerance as ageing brings many alterations in immune responses. Herein, we demonstrated that both the oral tolerance and pattern of immune reactivity triggered in early life were kept up to 15 months regarding the magnitude of antibody production, cell proliferation and cytokine profile when compared to immune responses induced in old mice. Therefore, our results corroborate with a promising proposal for prevaccination during childhood and young age, and a booster in older age, to make sure that the primary immunization in early life is not lost in aged individuals.

XP-828L in the Treatment of Mild to Moderate Psoriasis: Randomized, Double-Blind, Placebo-Controlled Study

Background:

XP-828L, a protein extract obtained from sweet whey, has demonstrated potential benefit for the treatment of mild to moderate psoriasis in an open-label study.

Objective:

To study in a randomized, double-blind, placebo-controlled study the safety and efficacy of XP-828L in the treatment of mild to moderate psoriasis.

Design:

XP-828L 5 g/d (group A, n = 42) or placebo (group B, n = 42) was given orally for 56 days followed by XP-828L 5 g/d in group A and by XP-828L 10 g/d in group B for an additional 56 days.

Results:

Patients receiving XP-828L 5 g/d for 56 days had an improved Physician's Global Assessment (PGA) score compared with patients under placebo ( p < .05). Considering the data of group A only, the PGA score improved from day 1 to day 56 ( p < .01); the Psoriasis Area and Severity Index score improved as well, but to a lesser extent ( p < .05).

Conclusion:

Oral administration of 5 g/d XP-828L compared with a placebo significantly improved the PGA score of patients with mild to moderate psoriasis.

Effect of a protein-free diet in the development of food allergy and oral tolerance in BALB/c mice

The aim of the present study was to investigate the effect of a protein-free diet in the induction of food allergy and oral tolerance in BALB/c mice. The experimental model used was mice that were fed, since weaning up to adulthood, a balanced diet in which all dietary proteins were replaced by amino acid diet (Aa). The absence of dietary proteins did not prevent the development of food allergy to ovalbumin (OVA) in these mice. However, Aa-fed mice produced lower levels of IgE, secretory IgA and cytokines. In addition, when compared with mice from control group, Aa-fed mice had a milder aversive reaction to the allergen measured by consumption of OVA-containing solution and weight loss during food allergy development. In addition, mice that did not have dietary proteins in their diets were less susceptible to induction of oral tolerance. One single oral administration was not enough to suppress specific serum Ig and IgG1 levels in the Aa-fed group, although it was efficient to induce suppression in the control group. The present results indicate that the stimulation by dietary proteins alters both inflammatory reactivity and regulatory immune reactivity in mice probably due to their effect in the maturation of the immune system.

Oral gene application using chitosan-DNA nanoparticles induces transferable tolerance

Oral tolerance is a promising approach to induce unresponsiveness to various antigens. The development of tolerogenic vaccines could be exploited in modulating the immune response in autoimmune disease and allograft rejection. In this study, we investigated a nonviral gene transfer strategy for inducing oral tolerance via antigen-encoding chitosan-DNA nanoparticles (NP). Oral application of ovalbumin (OVA)-encoding chitosan-DNA NP (OVA-NP) suppressed the OVA-specific delayed-type hypersensitivity (DTH) response and anti-OVA antibody formation, as well as spleen cell proliferation following OVA stimulation. Cytokine expression patterns following OVA stimulation in vitro showed a shift from a Th1 toward a Th2/Th3 response. The OVA-NP-induced tolerance was transferable from donor to naïve recipient mice via adoptive spleen cell transfer and was mediated by CD4(+)CD25(+) T cells. These findings indicate that nonviral oral gene transfer can induce regulatory T cells for antigen-specific immune modulation.

Efeito protetor das frações proteicas do soro de leite em camundongos Balb/C infectados por Escherichia coli O157: H7

Avaliou-se o efeito protetor das frações proteicas do soro do leite sobre as vilosidades intestinais de camundongos Balb/C, fêmeas, infectadas por Escherichia coli O157:H7. Foram utilizados 48 animais, distribuídos aleatoriamente em oito grupos de seis fêmeas cada um. Os animais dos grupos 1 e 2 (controles) receberam dieta AIN93G padrão; os dos grupos 3 e 4, AIN93G + alfalactalbumina; os dos grupos 5 e 6, AIN93G + betalactoglobulina e os dos grupos 7 e 8, AIN93G + concentrado proteico total e água ad libitum por sete dias. No dia zero, os animais dos grupos 2, 4, 6 e 8 foram inoculados, por meio de cânula de gavagem, com 0,5mL de E. coli O157:H7, na concentração de 7 x 10(10)UFC/mL. Os animais foram acompanhados clinicamente e sacrificados, no oitavo dia experimental. Verificou-se, por meio de exames histológicos e da morfometria, que as frações betalactoglobulina e alfalactalbumina exerceram efeito protetor sobre as vilosidades intestinais do jejuno distal e do íleo (P<0,05), respectivamente. O concentrado proteico total não demonstrou efeito protetor sobre as vilosidades intestinais.

Vasoactive intestinal polypeptide enhances oral tolerance by regulating both cellular and humoral immune responses

Vasoactive intestinal polypeptide (VIP) is an important signal molecule of the neuroendocrine-immune network. In the immune system, VIP has been found to act as an endogenous anti-inflammatory mediator. In the current study, it was found that VIP administration regulated oral tolerance by inhibiting both cellular and humoral responses. Compared with vehicle-treated mice, mice treated with VIP during the development of ovalbumin (OVA)-induced oral tolerance exhibited the least delayed-type hypersensitivity (DTH), showed profoundly reduced proliferative capacity and produced less interferon (IFN)-gamma, interleukin (IL)-6, IL-5, IL-10 and interferon-inducible protein (IP-10). IgA-secreting cells in the gut as well as OVA-specific IgG and other isotypes levels in plasma were inhibited significantly after VIP-treatment. The VPAC2 receptor may be involved in VIP-mediated oral tolerance enhancement. Taken together, these results suggest that VIP enhanced oral tolerance via regulating both cellular and humoral responses.

Immunomodulation by a Malleable Matrix Composed of Fermented Whey Proteins and Lactic Acid Bacteria

Functional foods and nutraceuticals have gained in popularity over the last 10 years. Among natural health products, whey proteins and fermented milk products are paramount. A malleable protein matrix (MPM), composed of whey fermented by a lactic acid bacterium, capsular exopolysaccharides, vitamins, minerals, and peptides generated during the fermentation process, has the potential to be unique by combining multiple health-promoting components. Forced feeding experiments on healthy animals were performed to evaluate the immunomodulatory effect of MPM. Glutathione production, antibody response, and the modulation of leukocyte populations were monitored. The stimulation of the immune system by MPM consumption was evident as seen by the increased polymorphonuclear cell counts and intracellular glutathione levels. The absence of MPM-specific antibody production indicated a lack of undesirable immune recognition of MPM. The MPM, with its immunomodulatory properties, has the potential to be a food substitute or a functional food for maintenance of general immune health.

Cow's milk allergy: a complex disorder

Cow's milk allergy (CMA) is a complex disorder. Numerous milk proteins have been implicated in allergic responses and most of these have been shown to contain multiple allergenic epitopes. There is considerable heterogeneity amongst allergic individuals for the particular proteins and epitopes to which they react, and to further complicate matters, allergic reactions to cow's milk are driven by more than one immunological mechanism. Finally, the incidence and dominant allergic mechanisms change with age, with IgE-mediated reactions common in infancy and non-IgE-mediated reactions dominating in adults. The complexity of CMA has lead to many public misconceptions about this disorder, including confusion with lactose intolerance and frequent self-misdiagnosis. Indeed, the prevalence of self-diagnosed CMA in the community is 10-fold higher than the clinically proven incidence, suggesting a sizable population is unnecessarily eschewing dairy products. Avoidance of dairy foods, whether for true or perceived CMA, carries with it nutritional consequences and the provision of appropriate nutritional advice is important. In this review, the epidemiology and natural course of CMA is discussed along with our current understanding of its triggers and immunological mechanisms. We examine current strategies for the primary and secondary prevention of allergic sensitization and the ongoing search for effective therapies to ultimately cure CMA.

A novel model of sensitization and oral tolerance to peanut protein

The prevalence of food allergic diseases is rising and poses an increasing clinical problem. Peanut allergy affects around 1% of the population and is a common food allergy associated with severe clinical manifestations. The exact route of primary sensitization is unknown although the gastrointestinal immune system is likely to play an important role. Exposure of the gastrointestinal tract to soluble antigens normally leads to a state of antigen-specific systemic hyporesponsiveness (oral tolerance). A deviation from this process is thought to be responsible for food-allergic diseases. In this study, we have developed a murine model to investigate immunoregulatory processes after ingestion of peanut protein and compared this to a model of oral tolerance to chicken egg ovalbumin (OVA). We demonstrate that oral tolerance induction is highly dose dependent and differs for the allergenic proteins peanut and OVA. Tolerance to peanut requires a significantly higher oral dose than tolerance to OVA. Low doses of peanut are more likely to induce oral sensitization and increased production of interleukin-4 and specific immunoglobulin E upon challenge. When tolerance is induced both T helper 1 and 2 responses are suppressed. These results show that oral tolerance to peanut can be induced experimentally but that peanut proteins have a potent sensitizing effect. This model can now be used to define regulatory mechanisms following oral exposure to allergenic proteins on local, mucosal and systemic immunity and to investigate the immunomodulating effects of non-oral routes of allergen exposure on the development of allergic sensitization to peanut and other food allergens.