3,3′-Diindolylmethane Improves Intestinal Permeability Dysfunction in Cultured Human Intestinal Cells and the Model Animal Caenorhabditis elegans

Abstract

3,3′-Diindolylmethane (DIM), a digestive metabolite originating from cruciferous vegetables, has dietary potential for the treatment of various human intestinal diseases. Although intestinal permeability dysfunction is closely related to the initiation and progression of human intestinal inflammatory diseases (IBDs), the effect of DIM on intestinal permeability is unclear. We evaluated the effect of DIM on the intestinal permeability of human intestinal cell monolayers and the animal model Caenorhabditis elegans, which were treated with IL-1β and Pseudomonas aeruginosa, respectively, to mimic IBD conditions. DIM substantially restored the intestinal permeability of differentiated Caco-2 cells by enhancing the expression of tight junction proteins (including occludin and ZO-1). Compared to the IL-1β single treatment (551.0 ± 49.0 Ω·cm2), DIM (10 μM) significantly increased the transepithelial electrical resistance (TEER) of Caco-2 cell monolayers (919.0 ± 66.4 Ω·cm2, p < 0.001). DIM also ameliorated the impaired intestinal permeability and extended the lifespan of C. elegans fed P. aeruginosa. The mean lifespan of DIM-treated worms (10.8 ± 1.3 days) was higher than that of control-treated worms (9.7 ± 1.1 days, p < 0.01). Thus, DIM is a potential nutraceutical candidate for the treatment of leaky gut syndrome by improving intestinal permeability.

Antimicrobial Biophotonic Treatment of Ampicillin-Resistant Pseudomonas aeruginosa with Hypericin and Ampicillin Cotreatment Followed by Orange Light

“…We found a clear difference based on microscopic observation after C. elegans was fed APDT-treated and live P. aeruginosa PAO1 for 48 h. After 3 h of staining, we observed that most infected worms absorbed the dye, as their gut was damaged, with deep blue staining, as seen in Figure 9C. Conversely, APDT P. aeruginosa-fed worms showed little staining or blue color in the body, indicating that their gut was [36]. To clearly understand the infection model, we used Brilliant Blue FCF dye, which facilitates the evaluation of gut permeability during infection by P. aeruginosa PAO1.…”

“…The intestinal permeability of C. elegans was measured because bacterial toxicity can be clearly observed in this nematode model, especially in the case of P. aeruginosa PAO1-infected worms, where high toxicity leads to intestinal permeability dysfunction [36]. Age-synchronized L4 worms were treated with E. coli OP50, live P. aeruginosa PAO1, or APDT-treated P. aeruginosa PAO1 for 48 h at 20 • C. The treated worms were transferred to 96-well plates containing 100 µL of Brilliant Blue FCF and incubated for 3 h at 20 • C. The Brilliant Blue FCF was mixed with an E. coli OP50 culture to a concentration of 5% w/v.…”

“…aeruginosa is a good pathogen model for severe infection in C. elegans [36], which is itself a representative animal model for observing the therapeutic effects and side effects of biological treatments. It has already been reported that P. aeruginosa PAO1 is toxic and pathogenic to C. elegans, and can rapidly infect these nematodes [36]. For all treatments, including the control, bacterial cells were fed to the egg stage of N2 wildtype C. elegans, and the growth rate was evaluated by measuring body length after 96 h, as seen in Figure 8.…”

“…P. aeruginosa PAO1 can easily cause serious intestinal infection within a very short time in C. elegans [36]. To clearly understand the infection model, we used Brilliant Blue FCF dye, which facilitates the evaluation of gut permeability during infection by P. aeruginosa PAO1.…”

“…C. elegans has been reported as a model for Gram-positive and Gram-negative bacterial and fungal infections [35]. P. aeruginosa PAO1 was the first pathogen shown to infect and accumulate in the intestine of C. elegans [36], and this strain can also kill C. elegans [37]. In our study, we used the C. elegans model to demonstrate the effects of APDT on P. aeruginosa PAO1 pathogenesis through microscopic observation of worm growth and gut permeability.…”