Yuxin Wang, PhD: No relevant financial relationship(s) with ineligible companies to disclose.
Objectives: To investigate the impact, mechanism, and transport of the microbial metabolites on epithelial monolayer.
Methods: We established a model system by seeding 1×105 cells/cm2 Caco2 and HT29 cells (9:1) onto the apical chamber in a 12-well transwell plate in DMEM with 10% FBS and 1% penicillin-streptomycin at 37°C with 5% CO2. Transepithelial electrical resistance was monitored. Upon monolayer formation, the cells were treated with 1-10 mM SCFA sodium in the apical part in PBS, with PBS-only and DMEM-only controls. SCFA and glucose levels were analyzed using gas chromatography and GOPOD. Cell viability was assessed using a cell counting kit, propidium iodide staining, and fluorescence microscopy.
Results: After 10 mM SCFA sodium treatment for 7 days, TEER values (Ω · cm2) were: DMEM (248.26 ± 11.01), PBS (268.8 ± 23.49), butyrate (698.13 ± 101.58, P < 0.0001 vs DMEM, PBS), butyrate with low glucose DMEM basolateral (1422.4 ± 151.76, P < 0.0001 vs DMEM, PBS, butyrate with high glucose DMEM), Acetate and propionate increased TEER a little.
The propionate (mM) in the apical chamber was 2.30 ± 0.30, basolateral was 3.56 ± 0.28 (P = 0.002) with 2.20 ± 0.07 g/L glucose left; High-glucose DMEM basolaterally with butyrate (mM) in the apical chamber was 2.30 ± 0.04, basolateral was 3.15 ± 0.29 (P = 0.007) with 2.88 ± 0.19 g/L glucose left (P < 0.001 vs PBS, acetate, propionate); Low-glucose DMEM basolaterally, apical butyrate was 2.11 ± 0.04, basolateral was 3.28 ± 0.07 (P < 0.0001). No acetate transportation.
Sodium butyrate decreased cell viability to 42.17 ± 2.03% (P < 0.0001 vs DMEM, PBS), while sodium propionate significantly decreased it to 62.53 ± 2.20%. Sodium acetate did not have an effect. PI staining revealed no difference in nuclei staining between DMEM and different sodium butyrate concentrations (1, 2, 5, 10 mM).
Conclusions: Our study reveals that a basolaterally fed co-cultured epithelial monolayer facilitates microbiome-epithelium interaction studies. The cells transport butyrate and propionate from apical to basolateral side and utilize butyrate alongside glucose. Sodium butyrate decreased cell viability yet significantly enhanced TEER. These findings establish a relevant model for investigating microbiome-epithelial metabolic interactions, elucidating the complex interplay between microbiome metabolites and intestinal epithelium.
