Eprinomectin (EPR) is a macrocyclic lactone antiparasitic widely used in veterinary medicine. Although the off-label oral use of the pour-on formulation of EPR is known to be effective and practical, data regarding its interactions with foods or vitamin supplements that may affect intestinal absorption remain limited. This study investigated the effects of vitamin A (VA) and vitamin E (VE) on the transepithelial permeability of EPR using the Caco-2 cell monolayer model. An analytical method for EPR quantification was developed using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The integrity of tight junction dynamics in epithelial monolayers was monitored using transepithelial electrical resistance (TEER) throughout the 21-day differentiation protocol. Apparent permeability coefficients (P-app) were calculated in both apical-to-basolateral and basolateral-to-apical directions and compared between EPR alone and EPR combined with the vitamins. EPR alone exhibited moderate permeability across Caco-2 monolayers (7.64 +/- 2.27 & times; 10(-6) cm/s). Notably, our results demonstrate that co-treatment of EPR with VA alone, as well as co-treatment with the combination of VA and VE, significantly reduced EPR permeability in vitro (P < 0.001). These findings highlight possible food/nutrient-drug interactions relevant to veterinary oral drug administration, and additional mechanistic and in vivo studies will be necessary to clarify the underlying pathways.
Edwardsiella tarda is an important fish pathogen that causes outbreaks leading to significant losses in aquacultural species such as African catfish (Clarias gariepinus). In order to study host-pathogen interactions and design preventive strategies, it is essential to prepare a reliable experimental infection model. The aim of this study was to develop a reproducible immersion challenge model for E. tarda infection in C. gariepinus. The present study consisted of preliminary experiments and a main experiment evaluating the different routes of infection and the bacterial concentrations and exposure durations in an immersion bath. Preliminary experiments demonstrated that infection could be induced by either intraperitoneal injection or immersion bath, and that infection was more successful at higher concentrations. The main experiment involved two concentrations (108 and 2 × 108 CFU/ml) of immersion bath and two immersion durations (1 and 2 h), each repeated twice. The fish were monitored for clinical signs and mortality throughout the experiment and samples were collected on day 10 post-infection for haematological, immunological, and pathological assessment. High-dose immersion reliably induced infection, with disease progression depending on bacterial concentration and exposure duration. This established model is a practical and reproducible tool for future studies on the pathogenesis and immunity of C. gariepinus, as well as the use of immunostimulants and therapeutics.
