Pectin-based encapsulation systems for the protection of beneficial bacterial species and impact on intestinal barrier function in vitro

Pectin is a complex polysaccharide important to the pharmaceutical and food industry, and due to its versatility, cheapness, and notable health benefits, it is proposed to be investigated as an encapsulation material to protect sensitive food components such as living bacteria during their passage through the gastrointestinal tract. The main objective of this study was to evaluate both, the ability of pectin-based beads to maintain the viability and functionality of L. plantarum WCFS1 and the protective effect on intestinal epithelial barrier disruption in vitro. Pectin isolated from lemon with two degrees of methylation (DM18 and DM88) was used to form microbeads with either alginate or chitosan, producing four bead types, which were alginate/pectin DM18 (AlgDM18), alginate/pectin DM88 (AlgDM88), chitosan/pectin DM18 (ChitoDM18), and chitosan/pectin DM88 (ChitoDM88).

The beads were loaded with L. plantarum, and it was demonstrated that all pectin-based beads could preserve the viability of L. plantarum after encapsulation. While some differences in metabolism was observed, the alginate-pectin beads exhibited higher activity and loading capacity. Then these beads were tested on intestinal epithelial cells to assess their protective impact in the presence of a barrier disruptor A23187. The effect on gut barrier function demonstrates that the composition of the microbeads significantly affected their protective effects. Empty ChitoDM88 beads demonstrated protective effects by delaying barrier disruption and modulating the release of gut epithelial cell-specific cytokines. They increased the production of CCL20 while reducing levels of IL-8 and IL-13, which are markers of inflammation.

L. plantarum WCFS1-loaded Chitosan DM88-pectin microbeads provided the strongest protection. These beads not only delayed disruption of the gut epithelial barrier but also increased epithelial barrier function before and after treatment of the monolayer with the A23187 disruptor. Additionally, the loaded ChitoDM88 beads upregulated key genes associated with the tight junction integrity of the intestinal epithelium, including ZO-1, Occludin, and Claudin-1, further supporting their protective role. The immune response was also modulated by the loaded ChitoDM88 beads, as they increased CCL20 production and reduced IL-8 levels, highlighting a bead-type-dependent impact on epithelial immune signaling.

This study demonstrates that pectin-based microbeads can preserve the viability and functionality of encapsulated L. plantarum, protecting against gut barrier impairment. The results highlight pectin's potential as a promising polymer for probiotic delivery, with encapsulation effectiveness depending on the pectin's methylation degree and the stabilizing agent used.