Background: Intestinal epithelial barrier (IEB) dysfunction is related to multiple gastrointestinal disorders, notably inflammatory bowel disease (IBD). Betulinic acid (BA), a compound derived from birch bark, has demonstrated potential therapeutic benefits in IBD. Nevertheless, the impact of BA on IEB function has not been fully elucidated. Methods: The current study aimed to explore the potential underlying mechanisms of BA in dextran sodium sulfate (DSS)-induced IBD in mice and co-culture models involving Caco-2/HT29-MTX-E12 cell monolayers or mouse intestinal organoids (IOs) in conjunction with macrophages stimulated by lipopolysaccharide (LPS). Results: In vivo, BA treatment significantly improved body weight and colon length, alleviated disease activity index (DAI) scores, and reduced colonic histopathological injury in IBD mice. In vitro, BA reduced the flux of FITC-dextran; increased the TEER; and decreased the production of IL-6, IL-1β, and TNF-α while increasing IL-10 mRNA levels. Additionally, BA enhanced IEB formation by upregulating ZO-1, occludin (OCLN), and claudin-1 (CLDN1). Molecular docking studies revealed significant docking scores and interactions between BA and PPAR-γ. Moreover, BA significantly upregulated PPAR-γ protein expression, decreased NF-κB and MLC2 phosphorylation, and reduced MLCK protein expression. However, this effect was reversed by GW9662, an effective PPAR-γ antagonist. Conclusions: The findings reveal that BA mitigates IBD by safeguarding the intestinal barrier against dysfunction. This effect may be attributed to its ability to suppress inflammation and enhance the expression of tight junction proteins by modulating the PPAR-γ/NF-κB signaling pathway.

Background: Students’ engagement with learning materials and discussions with teachers and peers before and after lectures are among the keys to the successful implementation of blended programs. Mixed results have been reported by previous studies on blended learning. This study evaluated the effectiveness of embedding a teacher-supervised online discussion platform in a blended embryology course in terms of its impact on students’ capabilities to handle difficult and cognitively challenging tasks.Methods: Two forms of blended learning were investigated and compared in this study. Students in the control group (n = 85) learned online materials before each class, followed by classroom instruction and activities in which face-to-face discussion and communication between students were encouraged. Students in the experimental group (n = 83) followed a similar procedure with an additional teacher-supervised online discussion platform to guide, supervise and evaluate their learning progress. All participants were first-year medical students in clinical medicine at Dalian Medical University who had enrolled in 2017. All participants took the final exam to test their learning outcomes.Results: The embryology grades of students in the experimental group were significantly higher than those of students in the control group (p = 0.001). Additionally, the scores of students in the experimental group on questions with a high difficulty level (p = 0.003) and questions assessing high-order cognitive skills (p = 0.003) were higher than those of students in the control group; the effect size was moderate (η² > 0.05).Conclusions: In blended embryology courses, compared with learner-led and face-to-face discussion, the teacher-supervised online discussion platform has great potential to enable students to achieve higher grades and solve difficult and cognitively challenging tasks.