Abstract
We designed and conducted two in vitro experiments to evaluate the effects of two Bacillus spp. probiotics on gut barrier integrity using the transepithelial electrical resistance (TEER) assay under two different challenge models. In Exp. 1, intestinal epithelial cells received or not (CON) B. paralicheniformis 809 (BLI) or B. subtilis 810 (BSU) at a rate of 1 × 108 colony forming units (CFU)/transwell. Two hours after treatment application (CON, BLI, or BSU), 5 mM of the reactive oxygen species hydrogen peroxide, mimicking mucosal oxidative stress, was added alone (HYP) or with each of the Bacillus spp. (HYP + BLI or HYP + BSU). In Exp. 2, cells were assigned to the same treatments as in Exp. 1 (CON, BLI, and BSU), or mycotoxin deoxynivalenol (DON), which was added alone or in combination with BLI or BSU, resulting in another two treatments (DON + BLI and DON + BSU). Transepithelial electrical resistance was measured for 14 h postchallenge. In Exp. 1, a treatment × hour interaction was observed for TEER (P < 0.0001). Adding BLI and BSU resulted in greater TEER values vs. CON for most of the experimental period (P < 0.02), whereas HYP reduced mean TEER and area under the curve (AUC), while increasing the amount of sugar that translocated through the monolayer cells (P < 0.001). A treatment × hour interaction was also observed in Exp. 2 (P < 0.0001), as DON led to an immediate and acute drop in TEER that lasted until the end of the experimental period (P < 0.0001). Both BLI and BSU alleviated the DON-induced damaging effects on the integrity of intestinal epithelial cells, whereas both Bacillus spp. alleviated the damage caused by DON alone and the proportion of sugar that translocated through the monolayer cells was not different between CON and DON + BLI (P = 0.14) and DON + BLI and DON + BSU (P = 0.62). In summary, both Bacillus spp. strains (B. paralicheniformis 809 and B. subtilis 810) were able to counteract the damaging effects of the challenge agents, hydrogen peroxide and deoxynivalenol, on gut barrier integrity.