Effect of simulated gastro-duodenal digestion on the allergenic reactivity of beta-lactoglobulin

• Main Authors: Bossios Apostolos, Theodoropoulou Maria, Mondoulet Lucie, Rigby Neil M, Papadopoulos Nikolaos G, Bernard Hervé, Adel-Patient Karine, Wal Jean-Michel, Mills Clare EN, Papageorgiou Photini
• Format: Article
• Language: English
• Published: Wiley 2011-08-01
• Series: Clinical and Translational Allergy
• Subjects: in vitro digestion; cow's milk allergy; β-lactoglobulin; flow cytometry; Basophil activation; skin prick test
• Online Access: http://www.ctajournal.com/content/1/1/6

<p>Abstract</p> <p>Background</p> <p>Cow's milk (CM) allergy affects about 2% of infants. The allergenicity of dietary proteins, including those from CM, has been related to their digestibility although the generality of the link and its causality remains to be demonstrated. In this study we use an in vitro digestion system, to investigate the digestibility of β-lactoglobulin (blg) during gastrointestinal transit and to assess the impact of this process on blg allergenic reactivity in CM allergic children.</p> <p>Methods</p> <p>Blg digesta were prepared using an <it>in vitro </it>digestion protocol simulating either gastric digestion alone or followed by duodenal digestion with or without phosphatidylcholine (PC). Biochemical analysis of blg digesta was performed by SDS-PAGE and their concentration was measured by a sandwich ELISA. Assessment of their allergenic reactivity was done <it>in vitro </it>by EAST inhibition, specific basophil activation (basotest) and lymphocyte proliferation (PCNA-flow cytometry) assays using sera and cells from patients allergic to blg and <it>in vivo </it>by skin prick testing (SPT) of these patients.</p> <p>Results</p> <p>Blg was only broken down to smaller peptides after gastro-duodenal digestion although a sizeable amount of intact protein still remained. Digestion did not modify the IgE binding capacity of blg except for gastro-duodenal digestion performed in the absence of PC. These results are consistent with the quantity of intact blg remaining in the digesta. Overall both gastric and gastroduodenal digestion enhanced activation of sensitized basophils and proliferation of sensitized lymphocytes by blg. However, there was a tendency towards reduction in mean diameter of SPT following digestion, the PC alone during phase 1 digestion causing a significant increase in mean diameter.</p> <p>Conclusions</p> <p>Digestion did not reduce the allergenic reactivity of blg to a clinically insignificant extent, PC inhibiting digestion and thereby protecting blg allergenic reactivity. SPT reactivity was reduced compared to blg immunoreactivity in <it>in vitro </it>tests.</p>