DIET DERIVED AGEs · The influence of processing method on the pro-inflammatory properties of food and pathogenesis of food-related diseases

The influence of processing method on the pro-inflammatory properties of food and pathogenesis of food-related diseases.

Background The majority of foods that are consumed in our developed society have been processed. Processing promotes a non-enzymatic reaction between proteins and sugars called Maillard reaction (MR). Maillard reaction products (MRPs) and advanced Maillard reaction products (AGEs) determine taste, smell and colour of many food products therefore the MR is highly relevant for the food industry. The MR has become an important public health concern since MRPs/AGEs have been shown to contribute to increasing prevalence of diet-related inflammatory diseases including food allergy, Alzheimer's, cancer and diabetes. Immunological mechanisms underlying initiation of the innate and adaptive immune responses by MRPs/AGEs are not completely understood. Bridging this knowledge gap will significantly improve nutritional quality of food and increase the prevention of diet-mediated inflammation and food allergy. Objectives This research project aimed to relate the different processing (heating) conditions of soy proteins with the pro-inflammatory potential and allergenic capacity of obtained MRPs/AGEs. The combination of food chemistry with molecular in vitro studies allowed to verify the following research questions: 1. Does MR occurring during heating of soy proteins affect the biological potential of soy proteins (IgE binding potential, immunoreactivity, allergenicity)? How it is related to the processing conditions (time of heating/ with or without sugar)? 2. Do soy-derived MRPs interact with the receptor for advanced glycation and products (RAGE)? Do the soy processing conditions influence affinity of formed MRPs to RAGE? 3. Is it possible to adjust the parameters of an existing food processing methods in order to reduce the pro-inflammatory potential of formed MRPs? Methods and results The extraction method and processing conditions of soy proteins have been selected and optimized to stay close to the industrial conditions. The Maillard reaction products (MRPs) were obtained by heating soy protein extract (SPE) at 121°C for 5, 10, 20, 30, 45, 60, 90 and 120 minutes with the presence of glucose. The control samples were heated at the same conditions without sugar. The processed SPE were subjected to a combination of multidisciplinary approach which allowed to measure and describe several key aspects of pro-inflammatory action of MRPs: (1) biochemistry of proteins to characterize the level of Maillard reaction under different processing (heating) conditions, (2) cell biology to study an interaction of MRPs with RAGE, (3) immunology and allergology to characterize the changes in allergenic potential of processed SPE, its’ capacity to degranulate basophils and interaction with antigen-presenting cells and T-lymphocytes. For this reason serum, full blood and peripheral blood mononuclear cells (PBMCs) isolated from healthy and soy allergic donors were used. SPE heated in the presence of glucose showed higher IgE binding-capacity when compared with its heated control. This observation stay in line with the results of basophils activation test where enhanced basophil activity was observed upon exposure to SPE heated in the presence of glucose. Five out of seven soy allergic patients showed increased levels of IL-13 and IL-5 after incubation of PBMCs with SPE heated with glucose. These results suggest that the changes in protein structure caused by Maillard reaction may create the new epitopes able to induce an immune response. To induce an allergic reaction the MRPs need to be recognized and taken up by antigen presenting cells and subsequently presented to T-cells. To indicate the mechanism by which MRPs altered the physiology of immune cells, two different methods (ELISA-based and cell-based) to measure the interaction of MRPs with RAGE were successfully optimized and applied into the study. Both tests showed that soy-derived MRPs interact with RAGE and the strength of the binding is positively correlated with both time of heating with glucose and the level of Maillard reaction. Therefore RAGE has been postulated as the mechanism via which the food-derived MRPs may activate the pro-inflammatory pathway of immune cells. This conclusion is supported by ability of soy-derived MRPs to generate ROS and activate the nuclear factor kappa B (NF-ᴋB) in RAGE transfected cell line. Conclusion This project provided a better molecular understanding of largely unknown mechanism of inflammation induced by food-derived Maillard reaction products. This approach stays in line with recommendations of World Health Organisation and policy of European Union who emphasise a need to enrich our understanding of food-related inflammatory diseases at the molecular level. Utilisation of the knowledge The outcomes of this project may be transferred to the food industry to develop healthier products, advise food safety authorities on better risk assessment strategies and improve the diagnosis and prevention of food-related chronic inflammatory diseases. The results contributed to improve the diagnosis of soy allergy by the cooperation with medical institutions. On the longer term, the outcomes may contribute to development of new treatment methods based on understanding of molecular mechanisms of food allergy and food-related inflammation. Close cooperation with food industry during realisation of the project allowed to transfer the knowledge to the industry which may help to improve the processing conditions in order to increase the quality of final product. Contact details Gosia Teodorowicz Marie Curie Postdoctoral Researcher Cell Biology and Immunology Group, Wageningen University, Wageningen, the Netherlands e-mail: gosia.teodorowicz@gmail.com

Data: CORDIS, © European Union