Chemicals in food and allergy: fact and fiction

CD4+ T cell responses in Balb/c mice with food allergy induced by trinitrobenzene sulfonic acid and ovalbumin

The rapid increase in atopic diseases is potentially linked to increased hapten exposure, however, the role of haptens in the pathogenesis of food allergy remains unknown. Further studies are required to elucidate the cluster of differentiation 4 positive (CD4+) T cell response to food allergy induced by haptens. Dendritic cells were primed by trinitrobenzene sulfonic acid (TNBS) as a hapten or ovalbumin (OVA) as a model antigen, in a cell culture model. BALB/c mice were sensitized using TNBS and/or OVA. Intestinal Th1/Th2 cell and ovalbumin specific CD4+ T cells proliferation, intestinal cytokines (interleukin‑4 and interferon‑γ) in CD4+ T cells were evaluated. TNBS increased the expression of T cell immunoglobulin and mucin domain‑4 and tumor necrosis factor ligand superfamily member 4 in dendritic cells. Skewed Th2 cell polarization, extensive expression of interleukin‑4, reduced expression of interferon‑γ and forkhead box protein P3 were elicited following concomitant exposure to TNBS and OVA, with reduced regulatory T cells in the mouse intestinal mucosa, whereas a Th1 response was detected when challenged by TNBS or OVA alone. This data suggests that TNBS, as a hapten, combined with food antigens may lead to a Th2 cell response in the intestinal mucosa.

Authentication of commercial candy ingredients using DNA PCR-cloning methodology

BACKGROUND

Commercial candies are consumed by all population age sectors worldwide. Methods for quality control and composition authentication are therefore needed for best compliance with consumers' preferences. In this study applications of DNA-based methodology for candy quality control have been tested. Eighteen samples of commercial candies (marshmallows, gumdrops, jelly, sherbet, gelatin-based desserts) produced by five countries were analyzed to identify the component species by polymerase chain reaction, cloning and sequencing of 16S rRNA and ribulose -1,5-diphosphate carboxylase oxygenase genes, and the species determined from BLAST comparison with universal databases and phylogenetic analysis.

RESULTS

Positive DNA extraction and amplification of the target genes were obtained for 94% of candies assayed, even those containing as little as <0.0005 ng µL(-1) DNA concentration. The results demonstrated that the species detected from DNA were compatible with the information provided on candy labels only in a few products. DNA traces of undeclared species, including fish, were found in most samples, and two products were labeled as vegetarian but contained porcine DNA.

CONCLUSION

Based on the inaccuracy found on the labels of sweets we recommend the use of DNA tests for quality control of these popular sweets. DNA tests have been useful in this field but next-generation sequencing methods could be more effective.

Trends in the utilization of food additives

The frequent media reports on food additives weakened consumers’ trust in food producers and food control authorities as well. Furthermore, consumers’ uncertainty is also raised by the fact that they obtain their information from inadequate, mistrustful sources and, therefore, consumers might avoid the consumption of certain foodstuffs. While food producers may react by replacing artificial components by natural ones, they try to emphasize the favourable characteristics of their products. The authors describe the main trends and efforts related to food additives. On the basis of the overview it can be concluded that – besides taking into consideration consumers’ needs – product development and research directions are promising. Food producers’ efforts may help to restore consumer confidence and trust and they may help them to have informed choice. Orv. Hetil., 154(46), 1813–1819.

Food-additive-induced urticaria: a survey of 838 patients with recurrent chronic idiopathic urticaria

BACKGROUND

Recurrent chronic idiopathic urticaria (RCIU) is a common skin condition that affects 0.1-3% of the population in the USA and Europe and accounts for nearly 75% of all 'ordinary' chronic urticaria (CU) cases.

METHODS

We studied 838 consecutive patients with RCIU referred to hospital between 1998 and 2003. Patients with known causes of CU were excluded. Clinical history, physical examination, and symptom diaries were evaluated during two periods, a diet-free period (1 week) and a food-additive-free diet (FAFD) period (4 weeks), respectively, and two double-blind placebo-controlled (DBPC) challenges of six food additives were administered. The first DBPC challenge included a mixture of the six food additives (DBPCmixed) given to all patients. The second DBPC challenge comprised the single food additives, administered at increasing doses (DBPCsingle) to patients with a positive DBPCmixed test and 105 patients with a negative DBPCmixed test, as a control.

RESULTS

The DBPCmixed challenge was positive in 116 patients. None of the 105 control patients had a positive DBPCsingle test. Only 31 DBPCsingle tests were positive in patients with positive DBPCmixed challenge. Twenty-four of the 116 patients showing a positive DBPCmixed challenge also had a positive DBPCsingle result.

CONCLUSIONS

Our results confirmed that food additive hypersensitivity reactions occurred in few RCIU patients using DBPCsingle challenge. The combination of the results of FAFD and DBPCmixed challenge seems to be of considerable practical interest for allergists, internists and dermatologists, rather than the data of clinical history and the results of DBPCsingle challenge, in patients with RCIU.

Short-term moderate aflatoxin B1 exposure has only minor effects on the gut-associated lymphoid tissue of Brown Norway rats

Aflatoxin B1 (AFB1) is toxic to the systemic immune system in various animal species, whereas little is known about its effect on the gut-associated lymphoid tissue (GALT). It may be hypothesized that the toxicity of AFB1 and its locally generated metabolites in the intestinal tissue may result in a disturbed intestinal integrity and, subsequently, in an impaired immune response towards dietary proteins. The objective of our study was to investigate the toxic effect of short-term moderate AFB1 exposure on the intestinal epithelium and on the immune cells associated with the intestinal tract. The toxicological potential of AFB1 and its metabolites to the intestinal epithelium was determined by measuring viability and genotoxic damage in isolated jejunal epithelial cells (comet assay) after 30 min incubation in vitro. In vivo toxicology studies were carried out with Brown Norway (BN) rats, which were exposed orally once a week with AFB1 (1 x 100 microg/kg body weight (b.w.)/week) for 5 consecutive weeks. Viability and genotoxicity were measured in explanted jejunal epithelial cells. For studying the effectiveness of AFB1 on immunological parameters BN rats were treated with a high (study 1: 1 x 1 mg/kg b.w./week) or a low (study 2: 1 x 100 microg/kg b.w./week) AFB1 dose for 5 consecutive weeks with or without ovalbumin (OVA). Mesenteric lymphocytes were isolated and proliferative responsiveness, secretion of interferon-gamma, and changes in lymphocyte subpopulations as well as mucosal mast cell specific protease and anti-OVA specific antibody concentrations were measured. In vitro, AFB1 ( >30 microM) induced genotoxicity in rat jejunal epithelial cells. The oral administration of AFB1 (1 x 100 microg/kg b.w./week) did not induce DNA damage in jejunal epithelial cells. The high AFB1 dose increased the number of CD8+ and CD8/CD71 + cells in mesenteric lymph nodes. The immune response towards OVA was not affected. The low AFB1 dose only reduced the proliferative responsiveness of mesenteric lymphocytes (P < 0.05). Serum concentrations of anti-OVA specific IgE antibody, of RMCPII, and the capacity of mesenteric lymphocytes to produce interferon-gamma were not impaired by AFB1. In conclusion, exposure to moderate doses of AFB1 does not damage the intestinal epithelium and has only minor effects on the GALT. The low exposure, as it may predominantly occur in western countries, does not appear to increase the risk for sensitization to dietary antigens.