Background: Airway fibroblasts have become a critical addition to all facets of structural lung tissue changes such as in human asthma and chronic obstructive pulmonary disease, but little is known about their role in the equine recurrent airway obstruction, a disease that resembles to the human asthma. Since the equine bronchial fibroblasts (EBF) have not been isolated and characterized yet, the use of defined medium was investigated. Results: Primary EBF were cultured on non-collagen coated flasks without serum or in the presence of fetal bovine serum (FBS) or horse serum (HS) or in serum depleted medium. EBF cultured in serum-free basal media and those serum deprived were not able to proliferate and even exhibited considerable cell death. In media containing FBS or HS, proliferation of the cells was reproducible between different primary cultures and cells demonstrated expression of vimentin. Large variations were found in the ability of FBS and HS to support growth and differentiation of EBF in monolayer culture. Indications of growth-promoting actions, increasing passage number as well as maintaining fibroblast morphology were found rather in FBS than in HS. EBF culturing in HS needed longer doubling and confluence time. The protein content of the cell pellets was higher in EBF cultured in medium containing HS than FBS. Alpha-smooth muscle actin seemed to be less expressed in EBF cultured in medium containing FBS than those in HS. Conclusions: In sum, serum addition to basal EBF medium enhanced EBF differentiation into myofibroblasts, and these findings are useful to develop in vitro fibroblast culture models that mimic in vivo physiological processes and to study airway disease mechanisms and remodeling.

Horses develop recurrent airway obstruction (RAO) that resembles human bronchial asthma. Differentiated primary equine bronchial epithelial cells (EBEC) in culture that closely mimic the airway cells in vivo would be useful to investigate the contribution of bronchial epithelium in inflammation of airway diseases. However, because isolation and characterization of EBEC cultures has been limited, we modified and optimized techniques of generating and culturing EBECs from healthy horses to mimic in vivo conditions.

The molecular mechanisms by which environmental pollutants including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or widely used imidazole fungicide prochloraz display their toxic effects in vertebrates are still not well understood. Using computer analysis, we recently identified nuclear aryl hydrocarbon receptor (AhR) binding sites termed "dioxin response elements" (DREs) in the 5'-untranslated region (5'-UTR) of efflux transporter ABCG2 (Accession No. EU570105) from the bovine mammary gland. As these regulatory motifs mediate regulation of target genes by AhR agonists including TCDD and prochloraz, we have systematically investigated the effect of both contaminants on functional ABCG2 transport activity in primary bovine mammary epithelial cells. TCDD or prochloraz doubled ABCG2-mediated Hoechst H33342 secretion. This effect was almost completely reversed by specific ABCG2 inhibitor Ko143. In further mechanistic studies, we showed that this induction was due to binding of activated AhR to DRE sequences in the ABCG2 5'-UTR. Receptor binding was significantly reduced by specific AhR antagonist salicyl amide. Induction of AhR by TCDD and prochloraz resulted in a time- and dose-dependent increase of ABCG2 gene expression and transporter protein levels. As ABCG2 represents the main mammary transporter for xenobiotics including drugs and toxins, exposure to prevalent AhR agonists may enhance transporter-mediated secretion of potential harmful compounds into milk. Through identification of mammary ABCG2 as a novel target gene of pesticide prochloraz and dioxin, our results may therefore help to improve the protection of breast-feeding infants and the consumer of dairy products.

The broiler industry is pivotal in meeting the growing global demand for highly nutritious animal protein foods. Hence, there is a continuous interest in identifying novel, alternative, and even unconventional feed resources that could help sustainably support chicken meat production and quality. In this view, the microalga Spirulina (Arthrospira, formerly Spirulina, platensis), due to its unique chemical composition and some ecological advantages offered by its cultivation over traditional agriculture, has attracted great attention in the poultry sector for potential application in broiler diets, either as a functional supplement or a replacer of conventional protein sources such as soybean meal. The studies conducted so far seem to have confirmed many of the initial expectations regarding the advantages that may derive from dietary Spirulina supplementation, documenting its capacity to positively influence the intestinal and general health status of broiler chickens, leading to improved or preserved productive performance (under normal or challenging conditions, respectively), as well as to increased disease resistance and survivability. Furthermore, dietary Spirulina supplementation has been shown to induce positive changes in some important traits of broiler meat quality. However, at present, the inclusion of Spirulina in broiler diet, especially but not solely in relation to the use as an alternative protein source, presents several technical and economic limitations. To increase the overall awareness around the actual usefulness and practical usability of Spirulina as a novel natural component of the broiler diet, this review paper seeks to provide a comprehensive and integrated presentation of what is currently known about this topic, highlighting critical issues that are still pending and would require further research efforts.