Brucella ceti, a zoonotic pathogen of major concern to cetacean health and conservation, is responsible for severe meningo-encephalitic/myelitic lesions in striped dolphins (Stenella coeruleoalba), often leading to their stranding and death. This study investigated, for the first time, the cellular prion protein (PrP^c) expression in the brain tissue from B. ceti-infected, neurobrucellosis-affected striped dolphins. Seven B. ceti-infected, neurobrucellosis-affected striped dolphins, found stranded along the Italian coastline (6) and in the Canary Islands (1), were investigated, along with five B. ceti-uninfected striped dolphins from the coast of Italy, carrying no brain lesions, which served as negative controls. Western Blot (WB) and immunohistochemistry (IHC) with an anti-PrP murine monoclonal antibody were carried out on the brain parenchyma of these dolphins. While PrP^c IHC yielded inconclusive results, a clear-cut PrP^c expression of different intensity was found by means of WB analyses in the brain tissue of all the seven herein investigated, B. ceti-infected and neurobrucellosis-affected cetacean specimens, with two dolphins stranded along the Italian coastline and one dolphin beached in Canary Islands also exhibiting a statistically significant increase in cerebral PrP^c expression as compared to the five Brucella spp.-negative control specimens. The significantly increased PrP^c expression found in three out of seven B. ceti-infected, neurobrucellosis-affected striped dolphins does not allow us to draw any firm conclusion(s) about the putative role of PrP^c as a host cell receptor for B. ceti. Should this be the case, an upregulation of PrP^c mRNA in the brain tissue of neurobrucellosis-affected striped dolphins could be hypothesized during the different stages of B. ceti infection, as previously shown in murine bone marrow cells challenged with Escherichia coli. Noteworthy, the inflammatory infiltrates seen in the brain and in the cervico-thoracic spinal cord segments from the herein investigated, B. ceti-infected and neurobrucellosis-affected striped dolphins were densely populated by macrophage/histiocyte cells, often harboring Brucella spp. antigen in their cytoplasm, similarly to what was reported in macrophages from mice experimentally challenged with B. abortus. Notwithstanding the above, much more work is needed in order to properly assess the role of PrP^c, if any, as a host cell receptor for B. ceti in striped dolphins.

The management of gastrointestinal disease in animals represents a significant challenge in veterinary and zootechnic practice. Traditionally, acute symptoms have been treated with antibiotics and high doses of zinc oxide (ZnO). However, concerns have been raised regarding the potential for microbial resistance and ecological detriment due to the excessive application of this compound. These concerns highlight the urgency of minimizing the use of ZnO and exploring sustainable nutritional solutions. Hydrolysable tannins (HTs), which are known for their role in traditional medicine for acute gastrointestinal issues, have emerged as a promising alternative. This study examined the combined effect of food-grade HTs and subtherapeutic ZnO concentration on relevant biological functions of Caco-2 cells, a widely used model of the intestinal epithelial barrier. We found that, when used together, ZnO and HTs (ZnO/HTs) enhanced tissue repair and improved epithelial barrier function, normalizing the expression and functional organization of tight junction proteins. Finally, the ZnO/HTs combination strengthened enterocytes’ defense against oxidative stress induced by inflammation stimuli. In conclusion, combining ZnO and HTs may offer a suitable and practical approach for decreasing ZnO levels in veterinary nutritional applications.

In the symptomatic treatment of gastrointestinal disorders, high dosages of zinc oxide (ZnO) were conventionally employed. However, concerns regarding the potential for microbial resistance and ecological detriment have arisen due to the excessive application of this compound. These concerns highlight the urgency to minimize the use of ZnO and to explore sustainable nutritional solutions. Hydrolysable tannins (HTs), known for their role in traditional medicine for acute gastrointestinal issues, emerge as a promising alternative. This study examined the combined effect of food-grade HTs and lower ZnO concentration on relevant biological functions of Caco-2 cells, a widely used model of the intestinal epithelial barrier. We found that, when used together, ZnO and HTs (ZnO/HTs) enhanced tissue repair and improved epithelial barrier function, normalizing the expression and functional organization of tight junction proteins. Finally, the ZnO/HTs combination strengthened enterocyte defence against oxidative stress induced by inflammation stimuli. In conclusion, combining ZnO and HTs may offer a suitable and practical approach for decreasing ZnO levels in veterinary medical applications.