*2.2. The Effect of Amoxicillin and Doxycycline on the Viability, Integrity, and Permeability of Jejunum Mucosa Explants*

The single exposure of mucosa explants to either AMX (50 µg/mL) or DOX (30 µg/mL) did not provoke a significant change in TEER values during 90 min of incubation. The final measurement of TEER indicated 76.8 <sup>±</sup> 3.1 and 70.1 <sup>±</sup> 2.2 Ohm·cm<sup>2</sup> for AMX- and DOX-treated jejunum tissues, respectively. In contrast, no addition of antibiotics caused a TEER reading of 77.1 <sup>±</sup> 1.2 Ohm·cm<sup>2</sup> (Figure 1). The use of AMX did not provoke any significant change in the penetration of paracellular transport markers because the flux of LY and MAN amounted to 41.8 <sup>±</sup> 5.3 and 230.6 <sup>±</sup> 5.0 ng/min/cm<sup>2</sup> , respectively (Figures 2 and 3). Similarly, AMX did not affect the penetration rate of the transcellular transport marker. The flux of CAF was measured as 2.4 <sup>±</sup> 0.1 <sup>µ</sup>g/min/cm<sup>2</sup> in the presence of this antibiotic and 2.6 <sup>±</sup> 0.1 <sup>µ</sup>g/min/cm<sup>2</sup> when the explants were incubated in AMXfree medium (Figure 4). Likewise, the addition of DOX did not modify the intensity of CAF penetration across mucosa explants. DOX revealed the tendency to increase the intensity of transportation of paracellular transport markers. The flux of LY and MAN reached 58.7 <sup>±</sup> 5.15 and 247.8 <sup>±</sup> 18.9 ng/min/cm<sup>2</sup> , respectively (Figures 2 and 3). Additionally, none of the tested antibiotics increased the release of LDH compared to the control conditions. The enzyme activity in the KRB amounted to 5.2 ± 0.2 and 5.4 ± 0.2% of total LDH activity for AMX and DOX, respectively (Figure 5).

### *2.3. The Effect of Combined Exposure to Deoxynivalenol and Amoxicillin or Doxycycline on the Viability, Integrity, and Permeability of Jejunum Mucosa Explants*

The combined exposure of mucosa explants to DON and one of the antibiotics did not provoke a more profound alteration in intestine integrity and permeability than the mycotoxin used solely. Simultaneous exposure to AMX + DON or DOX + DON did not alter the magnitude of the TEER drop compared to the effect of DON alone. TEER readings were at the same level and amounted to 54.2 <sup>±</sup> 2.9, 54.9 <sup>±</sup> 1.5, and 52.4 <sup>±</sup> 0.7 Ohm·cm<sup>2</sup> for AMX + DON, DOX + DON, and DON, respectively (Figure 1). In the case of the penetration of paracellular and transcellular transport markers through mucosa explants, there were no remarkable differences between tissue samples incubated only in the presence of DON and those incubated in a cocktail of DON and one of the antibiotics. The flux of LY came to 87.7 <sup>±</sup> 10.6, 101.9 <sup>±</sup> 7.8, and 89.5 <sup>±</sup> 13.2 ng/min/cm<sup>2</sup> for AMX + DON, DOX + DON, and DON, respectively (Figure 2). The penetration of MAN ranked at 317.3 <sup>±</sup> 15.7, 318.4 <sup>±</sup> 12.6, and 306.0 <sup>±</sup> 8.6 ng/min/cm<sup>2</sup> , respectively, for AMX + DON, DOX + DON, and DON-containing KRB, respectively (Figure 3). Similarly, the extra addition of AMX or DOX did not cause any significant change in CAF penetration across jejunum mucosa in comparison to the effect of DON (Figure 4). However, the rate of CAF penetration was significantly higher in the presence of DOX + DON when compared to the control trial. The cytotoxicity measured in the LDH leakage test was at the same level for explants incubated in DON-containing incubation medium with and without antibiotics (Figure 5).
