Lujic T, Gligorijevic N, Stanic-Vucinic D, Krstic Ristivojevic M, Mutic T, et al.
International journal of molecular sciences •
Ingestion is one of the main exposure routes of humans and animals to microplastics (MPs). During digestion, MPs can interact with both gastrointestinal enzymes and food proteins. This study investigated the adsorption of trypsin onto polypropylene (PP) and polyethylene terephthalate (PET) MPs, the influence of MPs on trypsin structure and activity, and the in vitro trypsin digestibility of bovine meat extract (BME) sarcoplasmic proteins and BME α-Gal-carrying allergens (α-GalA) in the presence of PP and PET MPs. Trypsin, BME and α-GalA proteins interact with MPs, resulting in the formation of a soft (SC) and hard (HC) corona. This interaction is dynamic, leading to the adsorption and desorption of protein through time. Trypsin adsorption onto MPs results in slight structural changes in the SC and bulk solution, while a trypsin fraction residing in the HC loses most of its specific activity. The presence of MPs slightly slows down the digestibility of proteins with a mass of 38 kDa, while it does not affect the digestion of α-GalA. According to our results, it is unlikely that realistic concentrations of MPs in the intestine would have significant effects on meat extract proteins' and allergens' digestibility by trypsin. We confirmed that during trypsin digestion, the corona on PP and PET MP is composed of BME sarcoplasmic proteins and allergenic α-Gal-carrying proteins.
Perusko M, Apostolovic D, Kiewiet MBG, Grundström J, Hamsten C, et al.
Allergy •
Mammalian meat is the most common trigger of the allergic reactions in patients with α-Gal syndrome (AGS). Milk and dairy, although less often, also cause a significant number of allergic manifestations. The aim of this study was to identify α-Gal-containing bovine milk proteins with allergenic properties among AGS patients. Thirty-eight AGS patients with IgE to milk were included in the study. Milk proteins were analyzed for the presence of α-Gal and for binding by patients' IgE using immunoblot, ImmunoCAP, and inhibition ELISA. Allergenicity of milk and milk proteins was assessed by basophil activation test. More than half of the AGS patients reported allergic reactions to milk or dairy products. Bovine γ-globulin (BGG), lactoferrin (LF), and lactoperoxidase (LPO) were identified as α-Gal carrying proteins which were recognized by AGS patients' IgE. Whey mirrored the anti-α-Gal and IgE reactivity of BGG, LF, and LPO. Eighty-nine percent of the patients displayed IgE to BGG, 91% to LF, and 57% to LPO. Inhibition of α-Gal-specific IgE binding was achieved by BGG, LF, LPO, and whey. These proteins also activated AGS patients' basophils. Interestingly, at lower concentrations, LF was the most potent inhibitor of IgE binding, and the most potent activator of basophils. BGG, LF, and LPO were all found to be relevant milk α-Gal-containing glycoproteins that bound AGS patients' IgE antibodies and activated their basophils. These proteins are probably involved in the allergic reactions to milk in AGS patients. LPO was for the first time shown to be an allergen.
Krstić Ristivojević M, Grundström J, Apostolović D, Radomirović M, Jovanović V, et al.
International journal of molecular sciences •
Transepithelial transport of proteins is an important step in the immune response to food allergens. Mammalian meat allergy is characterized by an IgE response against the carbohydrate moiety galactosyl-α-1,3-galactose (α-Gal) present on mammalian glycoproteins and glycolipids, which causes severe allergic reactions several hours after red meat consumption. The delayed reaction may be related to the processing of α-Gal carrying proteins in the gastrointestinal tract. The aim of this study was to investigate how protein glycosylation by α-Gal affects the susceptibility to gastric digestion and transport through the Caco-2 cell monolayer. We found that α-Gal glycosylation altered protein susceptibility to gastric digestion, where large protein fragments bearing the α-Gal epitope remained for up to 2 h of digestion. Furthermore, α-Gal glycosylation of the protein hampered transcytosis of the protein through the Caco-2 monolayer. α-Gal epitope on the intact protein could be detected in the endosomal fraction obtained by differential centrifugation of Caco-2 cell lysates. Furthermore, the level of galectin-3 in Caco-2 cells was not affected by the presence of α-Gal glycosylated BSA (bovine serum albumin) (BSA-α-Gal). Taken together, our data add new knowledge and shed light on the digestion and transport of α-Gal glycosylated proteins.
