Oral abstracts (<scp>OAS</scp>)

<p class="MsoNormal"><b>Background:</b> Bovine beta-casein A2 milk is becomingincreasingly popular, with both producers and consumers demonstrating a risinginclination towards its production. In the beta-casein locus, alleles A1 and A2exhibit disparity at amino acid position 67, wherein A1 codes for histidine andA2 codes for proline. The breakdown of A1 beta-casein leads to the generationof beta-casomorphin (BCM)-7, a bioactive peptide possessing morphine-likeproperties. The increasing preference for A2 milk is often attributed to itsperceived benefits, particularly its potential to elicit fewer inflammatoryresponses compared to A1 milk. However, the understanding of this subjectremains limited. This study aims to comprehensively examine the effects ofBCM-7 and BCM-9, bioactive peptides resulting from the digestion of A1 and A2milk, respectively, on the integrity of the gut epithelial barrier. <o:p></o:p> <p class="MsoNormal"><b>Method:</b> A microfluidic gut-on-a-chip plate wasemployed to form a tubular barrier utilizing Caco-2 cells, enabling theassessment of the impacts of BCMs on gut epithelial cells and their barrierfunction. The concentrations of peptides utilized in the study were selectedbased on their relevance in vivo, considering the presence of these compoundsin raw milk or cheese. Following cytotoxicity assessment, transepithelialelectrical resistance (TER) measurement, paracellular permeability assay, woundhealing assay, targeted proteomics using proximity extension assay, untargetedproteomics, and RNA sequencing were performed. <o:p></o:p> <p class="MsoNormal"><b>Results:</b> Monolayer cultures did not exhibitcytotoxicity upon exposure to bovine BCM-7 and BCM-9. In addition, nosignificant findings were observed in the targeted proteomics assessment. Basedon RNA sequencing results, alterations in the expression profile of 231 geneswere identified with BCM-7 (20 ug/ml), while BCM-9 did not show any significanttranscriptome changes. Among these, KLHDC7B, HOOK3, PKD1P2, G6PC1, L3MBTL1,IDI2-AS1, and DDX60L genes showed the highest upregulation (2.27 to 3.50 fold),while TFDP2, ANAPC13, and CXCL8 genes demonstrated the most significantdownregulation (−2.47 to −2.61 fold). Pathway analysis highlighted pathwaysassociated with cellular metabolism and biogenesis, encompassing signaltransduction, organelle organization and biogenesis, cytoskeleton, andmicrotubule organization, as well as cell cycle checkpoints. <o:p></o:p> <p class="MsoNormal"><b>Conclusion:</b> Taken together, while BCM-7 showedsignificant differences in transcriptomic profiling, BCM-9 displayed aninactive nature to Caco2 cells. Conflicts of interest: The authors did notspecify any links of interest.<o:p></o:p>