19 research outputs found
Binding of CML-Modified as Well as Heat-Glycated beta-lactoglobulin to Receptors for AGEs Is Determined by Charge and Hydrophobicity
Intake of dietary advanced glycation end products (AGEs) is associated with
inflammation-related health problems. Nε-carboxymethyl lysine (CML) is one of the best characterised
AGEs in processed food. AGEs have been described as ligands for receptors present on antigen
presenting cells. However, changes in protein secondary and tertiary structure also induce binding to
AGE receptors. We aimed to discriminate the role of different protein modifications in binding to AGE
receptors. Therefore, β-lactoglobulin was chemically modified with glyoxylic acid to produce CML
and compared to β-lactoglobulin glycated with lactose. Secondary structure was monitored with
circular dichroism, while hydrophobicity and formation of β-sheet structures was measured with
ANS-assay and ThT-assay, respectively. Aggregation was monitored using native-PAGE. Binding
to sRAGE, CD36, and galectin-3 was measured using inhibition ELISA. Even though no changes in
secondary structure were observed in all tested samples, binding to AGE receptors increased with
CML concentration of CML-modified β-lactoglobulin. The negative charge of CML was a crucial
determinant for the binding of protein bound CML, while binding of glycated BLG was determined
by increasing hydrophobicity. This shows that sRAGE, galectin-3, and CD36 bind to protein bound
CML and points out the role of negatively charged AGEs in binding to AGE receptors
Milk modulates compylobacter invasion into caco-2 intestinal epithelial cells
Raw milk is a recognized source of Campylobacter outbreaks, but pasteurization is an effective way to eliminate the causative agent of Campylobacteriosis. Whereas breastfeeding is protective against infectious diseases, consumption of formula milk is thought to be not. However, in relation to Campylobacter, such data is currently unavailable. Although both pasteurized and formula milk are pathogen free and prepared in a quality controlled manner, the effect they have on the virulence of Campylobacter species is unknown. Here, we studied the effect of cow, goat, horse, and formula milk on Campylobacter invasion into intestinal epithelial Caco-2 cells, a pathogenic feature of this bacterial species, using a gentamicin exclusion invasion assay. We found that all milk products modulated the invasion of Campylobacter species into the Caco-2 cells in a dose-dependent manner. Control experiments showed that the milks were not toxic for the Caco-2 cells and that the effect on invasion is caused by heat labile (e.g., milk proteins) or heat stable (e.g., sugar/lipids) components depending on the Campylobacter species studied. This in vitro study shows for the first time that pasteurized and formula milk affect the invasion of Campylobacter. We recommend a prospective study to examine whether pasteurized and formula milk affect Campylobacteriosis
Effects of bovine immunoglobulins on immune function, allergy, and infection
This review aims to provide an in depth overview of the current knowledge of the effects of bovine immunoglobulins on the human immune system. The stability and functional effects of orally ingested bovine immunoglobulins in milk products are described and potential mechanisms of action are discussed. Orally ingested bovine IgG (bovine IgG) can be recovered from feces, ranging from very low levels up to 50% of the ingested IgG that has passed through the gastrointestinal tract. In infants the recovered levels are higher than in adults most likely due to differences in stomach and intestinal conditions such as pH. This indicates that bovine IgG can be functionally active throughout the gastrointestinal tract. Indeed, a large number of studies in infants and adults have shown that bovine IgG (or colostrum as a rich source thereof) can prevent gastrointestinal tract infections, upper respiratory tract infections, and LPS-induced inflammation. These studies vary considerably in target group, design, source of bovine IgG, dosage, and endpoints measured making it hard to draw general conclusions on effectiveness of bovine immunoglobulin rich preparations. Typical sources of bovine IgG used in human studies are serum-derived IgG, colostrum, colostrum-derived IgG, or milk-derived immunoglobulins. In addition, many studies have used IgG from vaccinated cows, but studies using IgG from nonimmunized animals have also been reported to be effective. Mechanistically, bovine IgG binds to many human pathogens and allergens, can neutralize experimental infection of human cells, and limits gastrointestinal inflammation. Furthermore, bovine IgG binds to human Fc receptors which, enhances phagocytosis, killing of bacteria and antigen presentation and bovine IgG supports gastrointestinal barrier function in in vitro models. These mechanisms are becoming more and more established and explain why bovine IgG can have immunological effects in vivo. The inclusion of oral bovine immunoglobulins in specialized dairy products and infant nutrition may therefore be a promising approach to support immune function in vulnerable groups such as infants, children, elderly and immunocompromised patients
Strategies and future opportunities for the prevention, diagnosis, and management of cow milk allergy
The prevalence of food allergy has increased over the last 20-30 years, including cow milk allergy (CMA) which is one of the most common causes of infant food allergy. International allergy experts met in 2019 to discuss broad topics in allergy prevention and management of CMA including current challenges and future opportunities. The highlights of the meeting combined with recently published developments are presented here. Primary prevention of CMA should start from pre-pregnancy with a focus on a healthy lifestyle and food diversity to ensure adequate transfer of inhibitory IgG- allergen immune complexes across the placenta especially in mothers with a history of allergic diseases and planned c-section delivery. For non-breastfed infants, there is controversy about the preventive role of partially hydrolyzed formulae (pHF) despite some evidence of health economic benefits among those with a family history of allergy. Clinical management of CMA consists of secondary prevention with a focus on the development of early oral tolerance. The use of extensive Hydrolysate Formulae (eHF) is the nutrition of choice for the majority of non-breastfed infants with CMA; potentially with pre-, probiotics and LCPUFA to support early oral tolerance induction. Future opportunities are, among others, pre- and probiotics supplementation for mothers and high-risk infants for the primary prevention of CMA. A controlled prospective study implementing a step-down milk formulae ladder with various degrees of hydrolysate is proposed for food challenges and early development of oral tolerance. This provides a more precise gradation of milk protein exposure than those currently recommended
Analysis of T‐cell reactive regions and HLA‐DR4 binding motifs on the latex allergen Hev b 1 (rubber elongation factor)
A human dendritic cell-based method to identify CD4+ T-cell epitopes in potential protein allergens.
Maturation of the Immune Response
The innate immune system depends on features like extracellular and intracellular pattern recognition receptors (PRR) that recognize general molecular patterns. Different types of PRR have been described, identifying microbe-, pathogen-, and danger-associated molecular patterns (abbreviated as MAMP, PAMP, and DAMP, respectively). PRR enhance ligation and phagocytosis of microbes or have signaling ability allowing activation of the cell. Ligation of extracellular toll-like receptors (TLR) by bacterial ligands like lipopolysaccharide (LPS) (binds to TLR4), peptidoglycan (PGN) (TLR2), and flagellin (TLR5) results in MyD88-dependent production of inflammatory cytokines like interleukin (IL)-1ß, IL-6, IL-8, and partly TNF-a. The expression of TLRs is vast as they are found on the cell membranes of innate immune cells (dendritic cell (DC), macrophages, natural killer cells), cells of the adaptive immunity (T and B lymphocytes), and nonimmune cells (epithelial and en ..