Regulation of intestinal peptidases by nutrients in human fetuses and children

(Xeno)estrogen regulation of food allergy

Food allergy and other types of allergies are becoming epidemic in both the developed and developing countries. A large amount of information is available in literature that (xeno)estrogens can regulate the immune response in general, and the development of allergy in particular; however, the effect of (xeno)estrogens on food allergy is basically unknown. With increasing use of xenobiotics worldwide, chemicals with estrogenic activity have been accumulating in our environment. This review has summarized the current literature relating to the topic (xeno)estrogen regulation of food allergy. The effect of (xeno)estrogens on enterocytes, proteases for protein hydrolysis, dendritic cells and T-regulatory cells in the gastrointestinal tract has been discussed. Finally, considering the current confusion in literature regarding the effect of phytoestrogen genistein on the immune system, a brief discussion has been included for its effect on T(H)1-T(H)2 polarization, and possibly food allergy in its relation to windows of exposure. Sufficient evidences exist to support the notion that (xeno)estrogens can regulate food allergy, with the developmental periods more sensitive. Further clinical and animal studies are needed to determine the causal relationship between the exposure of (xeno)estrogens and incidence of food allergy, and the underlying mechanisms.

Comparison of intestinal gene expression in Atlantic cod (Gadus morhua) fed standard fish meal or soybean meal by means of suppression subtractive hybridization and real-time PCR

Gene expression was studied in Atlantic cod fed two different diets, fish meal (FM) and dehulled and extracted soybean meal (SBM). RNA was isolated from the distal part of the mid-intestine of Atlantic cod and suppression subtractive hybridization (SSH) was employed to screen for genes that showed changes in expression in response to the two dietary treatments. We made a cDNA subtracted library, isolated and sequenced 192 clones. Identification of 157 clones was predicted by BLAST. Most of the clones were previously unidentified in cod. Expression of 12 selected clones was further studied by quantitative PCR. Expression of four clones showing similarity to aminopeptidase N, transcobalamin I precursor, cytochrome P450 3A40, and ras-related nuclear protein was significantly up regulated in intestine of cod fed SBM compared to cod fed FM. A trend towards up regulation of a clone with similarity to fatty acid binding protein in SBM-fed cod was also observed. No significant differences in expression were observed for: transmembrane 4 superfamily protein member, polypeptide N-acetylgalactosaminyltransferase, glutathione peroxidase, peroxiredoxin 4, SEC61, F-BOX, and 14-3-3.

Aminopeptidase N Gene Expression and Abundance in Caprine Mammary Gland is Influenced by Circulating Plasma Peptide

This study examined the localization and the effect of circulating peptides on the expression of aminopeptidase N (EC 3.4.11.2) in caprine mammary gland. Four lactating goats in mid to late lactation were used in a crossover design and were subjected to 2 dietary treatments. Abomasal infusion of casein hydrolysate was used to increase the concentration of peptide-bound amino acid in the circulation. Samples of mammary gland tissue from each goat were taken by biopsy at the end of each treatment period to measure gene and protein expression of aminopeptidase N in the tissue. There were no measurable effects on feed intake and milk production for any of the treatments. Western blot analysis showed that aminopeptidase N is located on the basolateral side of parenchymal cells and not on the apical membranes. Abomasal infusion of casein hydrolysate caused a marked change in the profile of arterial blood free amino acids and peptide-bound amino acids smaller than 1500 Da. Abundance of aminopeptidase N mRNA and protein increased by 51 and 58%, respectively, in casein hydrolysate-infused goats compared with the control treatment. It was concluded that aminopeptidase N is one candidate actively involved in the mammary gland to support protein synthesis and milk production. In accordance with the nutritional conditions in the current experiment, it is suggested that aminopeptidase N expression is partly controlled by the metabolic requirements of the gland and postabsorptive forms of amino acids in the circulation.