Increased levels of hyaluronan and albumin after intestinal challenge in adult patients with cow's milk intolerance

Food allergy: separating the science from the mythology

Numerous genes are involved in innate and adaptive immunity and these have been modified over millions of years. During this evolution, the mucosal immune system has developed two anti-inflammatory strategies: immune exclusion by the use of secretory antibodies to control epithelial colonization of microorganisms and to inhibit the penetration of potentially harmful agents; and immunosuppression to counteract local and peripheral hypersensitivity against innocuous antigens, such as food proteins. The latter strategy is called oral tolerance when induced via the gut. Homeostatic mechanisms also dampen immune responses to commensal bacteria. The mucosal epithelial barrier and immunoregulatory network are poorly developed in newborns. The perinatal period is, therefore, critical with regard to the induction of food allergy. The development of immune homeostasis depends on windows of opportunity during which innate and adaptive immunity are coordinated by antigen-presenting cells. The function of these cells is not only orchestrated by microbial products but also by dietary constituents, including vitamin A and lipids, such as polyunsaturated omega-3 fatty acids. These factors may in various ways exert beneficial effects on the immunophenotype of the infant. The same is true for breast milk, which provides immune-inducing factors and secretory immunoglobulin A, which reinforces the gut epithelial barrier. It is not easy to dissect the immunoregulatory network and identify variables that lead to food allergy. This Review discusses efforts to this end and outlines the scientific basis for future food allergy prevention.

Bioecologic Control of Inflammation and Infection in Critical Illness

Surgical and medical emergencies and treatments are still affected by an unacceptably high rate of morbidity and mortality. Sepsis is the most common medical and surgical complication and the tenth most common cause of death. Antibiotics and antagonists and inhibitors of proinflammatory cytokines have not met expectations. Selective bowel decontamination is no longer a treatment option. After more than 30 randomized clinical trials and 30 years of dedicated efforts to combat sepsis by the use of various combinations of antibiotics, we seem ready to conclude that the vigorous use of antibiotics does not significantly reduce mortality in critically ill patients. Side effects and price constitute important obstacles, especially when it comes to use of cytokine antagonists and inhibitors.

Probiotic bacteria down-regulate the milk-induced inflammatory response in milk-hypersensitive subjects but have an immunostimulatory effect in healthy subjects

BACKGROUND

Probiotic bacteria can influence immune responses both specifically by stimulating antibody production and nonspecifically by enhancing phagocytosis of pathogens and modifying cytokine production.

OBJECTIVE

The authors hypothesized that probiotic bacteria can alleviate hypersensitivity by influencing phagocytes. The modulation of phagocytes may be different in healthy subjects compared with hypersensitive subjects.

SUBJECTS AND METHODS

In a double-blind, cross-over study, challenges with milk in milk-hypersensitive and healthy adults with or without an intestinal bacterial strain, Lactobacillus GG (ATCC 53103) were performed. The challenge-induced immunoinflammatory response was recorded by measuring the expression of phagocytosis receptors prior to and after the challenge using flow cytometry.

RESULTS

In milk-hypersensitive subjects, milk challenge increased significantly the expression of CR1, FcgammaRI and FcalphaR in neutrophils and CR1, CR3 and FcalphaR in monocytes. Milk with Lactobacillus GG prevented the increase of the receptor expression. In healthy subjects, milk challenge did not influence receptor expression while milk with Lactobacillus GG increased significantly the expression of CR1, CR3, FcgammaRIII and FcalphaR in neutrophils.

CONCLUSION

Probiotic bacteria appear to modulate the nonspecific immune response differently in healthy and hypersensitive subjects. This is seen as an immunostimulatory effect in healthy subjects, and as a down-regulation of immunoinflammatory response in milk-hypersensitive subjects.

The Influence of Mast Cells on Pathways of Transepithelial Antigen Transport in Rat Intestine

Luminal Ag challenge of intestinal segments from sensitized rats results in a rapid (∼3 min) secretory response. We previously showed in horseradish peroxidase (HRP)-sensitized rats that the initial phase of transepithelial Ag transport occurred via a transcellular route and was enhanced by sensitization. However, following the hypersensitivity reaction, Ag also crossed between epithelial cells. The aim of this study was to determine the role of mast cells in the altered transepithelial Ag transport. White spotting mast cell-deficient rats and +/+ littermate controls were sensitized to HRP. After 10 to 14 days, jejunal segments were resected, mounted in Ussing chambers, and challenged with HRP on the luminal side. Electron microscopy of jejunum fixed at 2 min showed a similarly enhanced endocytic transport of HRP in sensitized +/+ and Ws/Ws rats compared with naive controls. In sensitized +/+ rats, a secretory response occurred ∼3 min after challenge, and tissue conductance increased thereafter. Naive +/+ and sensitized Ws/Ws rats did not demonstrate a secretory response to HRP challenge, and conductance remained at baseline levels. The flux of HRP was elevated across tissue from sensitized +/+ rats but not across tissue from naive controls or sensitized Ws/Ws rats. The results indicate that sensitization enhances the initial phase of transepithelial uptake of Ag by transcytosis in a mast cell-independent manner. However, subsequent recruitment of the paracellular pathway for Ag transport in sensitized rats is dependent upon the presence of mast cells and occurs after the activation of such cells.

Elimination diet in cow's milk allergy: risk for impaired growth in young children

OBJECTIVE

The objective of this study was to evaluate the nutritional impact of therapeutic elimination diets and to identify risk factors predisposing infants with food allergy to poor growth.

STUDY DESIGN

We studied 100 children (mean age 7 months) with atopic dermatitis and challenge-proven cow's milk allergy and evaluated their growth during the symptomatic period before diagnosis and during the therapeutic elimination diet.

RESULTS

Clinical control of symptoms was achieved in all patients. The mean length SD score and weight-for-length index of patients decreased compared with those in healthy age-matched children, p < 0.0001 and p = 0.03, respectively. Low serum albumin was present in 6% of the patients, 24% had an abnormal urea concentration, and 8% had a low serum phospholipid docosahexaenoic acid. The delay in growth was more pronounced in a subgroup of patients with early onset than in those with later of symptoms (F = 6.665, p < 0.0001). The duration of breast-feeding correlated positively with the sum of n-3 polyunsaturated fatty acids (r = 0.39, p = 0.001) and with the relative amount of docosahexaenoic acid (r = 0.36, p = 0.002).

CONCLUSION

A delicate balance exists between the benefits and the risks of elimination diets.

Mechanisms of gastrointestinal reactions to food

Much of the genetic information that modulates mucosal immune responses was encoded several million years ago and has subsequently been subjected to modifications selected by the impact of microorganisms and food antigens. Confronted with these challenges, the intestinal immune system has developed two arms: (1) immune exclusion performed mainly by secretory IgA antibodies to inhibit colonization of pathogenic microorganisms and penetration of harmful antigens; and (2) down-regulatory mechanisms to avoid local and peripheral overreaction (hypersensitivity) towards innocuous substances. The latter phenomenon is called oral tolerance and apparently explains why most individuals show no adverse immune reactions food. When the mucosal barrier function is insufficient, tolerance to dietary antigens is abrogated in genetically susceptible individuals. This is most likely to occur during the vulnerable period after birth before the immunoregulatory network has been established. Breast-feeding appears to be immunologically important during this period, not only to substitute for the infant's lacking secretory antibodies but also because of its immune-modulating effects.

Double blind, placebo controlled food reactions do not correlate to IgE allergy in the diagnosis of staple food related gastrointestinal symptoms

BACKGROUND

The mechanisms for adverse reactions to foods in the gastrointestinal tract are poorly understood. There is conflicting evidence in the literature on the role for IgE mediated allergy in gastrointestinal reactions to staple foods.

AIM

The aim was therefore to study the role of IgE mediated allergy in a group of patients with a history of gastrointestinal symptoms related to staple foods (cows' milk, hens' egg, wheat and rye flour) verified in double blind placebo controlled challenges (DBPCFC).

PATIENTS

Fifteen patients with DBPCFC, identified by screening of 96 consecutive patients referred to our allergy clinic for investigation of suspected gastrointestinal symptoms due to staple foods.

METHODS

The screening included diaries as well as elimination diets and open and blinded food challenges. The frequency of atopy were compared between the double blind positive and double blind negative patients.

RESULTS

The positive DBPCFC in the 15 patients included eight patients with milk intolerance, four with wheat flour, two with egg, and one with rye flour. There was no indications of an allergic pathogenesis in all 15 patients with positive DBPCFC, as the skin prick test and radioallergosorbent test were negative for the relevant allergens. The frequency of atopy was four of 21 (19%) in the double blind negative group and three of 15 (20%) in the double blind positive group.

CONCLUSION

In adult patients with staple food induced gastrointestinal symptoms, objectively verified by DBPCFC, there were no indications of IgE mediated allergy to the relevant foods suggesting other mechanisms in adults than in children. Future studies may include measures of local events in the shock organs in relation to food intake, for instance utilising inflammatory markers in jejunal fluids.