AUTHOR=Kuntz Sabine , Kunz Clemens , Borsch Christian , Hill David , Morrin Sinéad , Buck Rachael , Rudloff Silvia 

TITLE=Influence of microbially fermented 2´-fucosyllactose on neuronal-like cell activity in an in vitro co-culture system

JOURNAL=Frontiers in Nutrition

VOLUME=11

YEAR=2024

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2024.1351433

DOI=10.3389/fnut.2024.1351433

ISSN=2296-861X

ABSTRACT=<sec id="sec1"><title>Scope</title><p>2´-Fucosyllactose (2´-FL), the most abundant oligosaccharide in human milk, plays an important role in numerous biological functions, including improved learning. It is not clear, however, whether 2´-FL or a cleavage product could influence neuronal cell activity. Thus, we investigated the effects of 2´-FL, its monosaccharide fucose (Fuc), and microbial fermented 2´-FL and Fuc on the parameters of neuronal cell activity in an intestinal–neuronal transwell co-culture system <italic>in vitro</italic>.</p></sec><sec id="sec2"><title>Methods</title><p>Native <sup>13</sup>C-labeled 2´-FL and <sup>13</sup>C-Fuc or their metabolites, fermented with <italic>Bifidobacterium (B.) longum</italic> ssp<italic>. infantis</italic> and <italic>B. breve</italic>, which were taken from the lag-, log- and stationary (stat-) growth phases of batch cultures, were applied to the apical compartment of the co-culture system with Caco-2 cells representing the intestinal layer and all-<italic>trans</italic>-retinoic acid-differentiated SH-SY5Y (SH-SY5Y<sub>ATRA</sub>) cells mimicking neuronal-like cells. After 3 h of incubation, the culture medium in the basal compartment was monitored for <sup>13</sup>C enrichment by using elemental analysis isotope-ratio mass spectrometry (EA-IRMS) and effects on cell viability, plasma, and mitochondrial membrane potential. The neurotransmitter activation (BDNF, GABA, choline, and glutamate) of SH-SY5Y<sub>ATRA</sub> cells was also determined. Furthermore, these effects were also measured by the direct application of <sup>13</sup>C-2´-FL and <sup>13</sup>C-Fuc to SH-SY5Y<sub>ATRA</sub> cells.</p></sec><sec id="sec3"><title>Results</title><p>While no effects on neuronal-like cell activities were observed after intact 2´-FL or Fuc was incubated with SH-SY5Y<sub>ATRA</sub> cells, supernatants from the stat-growth phase of 2´-FL, fermented by <italic>B. longum</italic> ssp. <italic>infantis</italic> alone and together with <italic>B. breve</italic>, significantly induced BDNF release from SH-SY5Y<sub>ATRA</sub> cells. No such effects were found for 2´-FL, Fuc, or their fermentation products from <italic>B. breve</italic>. The BDNF release occurred from an enhanced vesicular release, which was confirmed by the use of the Ca<sup>2+</sup>-channel blocker verapamil. Concomitant with this event, <sup>13</sup>C enrichment was also observed in the basal compartment when supernatants from the stat-growth phase of fermentation by <italic>B. longum</italic> ssp. <italic>infantis</italic> alone or together with <italic>B. breve</italic> were used.</p></sec><sec id="sec4"><title>Conclusion</title><p>The results obtained in this study suggest that microbial products of 2´-FL rather than the oligosaccharide itself may influence neuronal cell activities.</p></sec>