Examinando por Autor "Zarza, C"

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Analysis of immunostimulatory responses and immune tolerance to β-glucans in rainbow trout cell lines.
(Elsevier, 2021-08-30) Ordás, MC; González- Torres, L; Arense, P; Heavyside, R; Zarza, C; Tafalla, C
β-glucans are widely used in fish diets as immunomodulators to enhance the defensive capacities of farmed animals and improve their resistance to pathogens. Despite their extensive use, the precise effects that β-glucans provoke on immune and intestinal cells in teleost fish have not yet been fully elucidated. In the current work, we have used the RTS11 monocyte-macrophage cell line and the RTgutGC intestinal epithelial cell line to further investigate the effects of β-glucans on rainbow trout (Oncorhynchus mykiss), determining the levels of transcription of a wide range of immune genes that code for pro-inflammatory cytokines/molecules, antimicrobial peptides or adhesion molecules. Our results show that RTS11 monocytes/macrophages are more reactive to β-glucans than intestinal epithelial cells. Despite this, β-glucans were able to enhance some of the transcriptional effects of Aeromonas salmonicida on RTgutGC cells as they did on RTS11 cells, evidencing some immunostimulatory effects on gut epithelial cells. Finally, we have also used these two cell lines to establish whether β-glucans induce tolerance, comparing the effects to those exerted by LPS. Pre-exposure of both cell lines to LPS strongly inhibited a secondary response to LPS that affected the transcription of many of the genes studied, confirming the potential of these cell lines to study mechanisms of immune tolerance. However, when both cell lines were stimulated with β-glucans, only interleukin 6 (IL6) transcription was significantly lower in cells that had been previously exposed to β-glucans in comparison to cells that had not been previously stimulated. These results provide valuable information concerning the immunostimulatory and potential tolerogenic effects exerted by β-glucans in both macrophages and gut epithelial cells.
Functional nutrition modulates the early immune response against viral haemorrhagic septicaemia virus (VHSV) in rainbow trout.
(Elsevier, 2019-11) Leal, E; Ordás, MC; Soleto, I; Zarza, C; McGurk, C; Tafalla, C
Although viruses represent a major threat for cultured fish worldwide, the commercialization of vaccines capable of providing effective and long-lasting protection is still lacking for most of these viral diseases. In this situation, the use of supplemented diets could be a suitable strategy to increase the immune status of the fish and reduce the impact of viral pathogens. Among possible immunostimulants that could be included in these functional feeds, some studies have previously shown that certain β-glucans can significantly increase certain immune parameters of fish and reduce the impact of viral diseases. However, the mechanisms through which β-glucans exert their activity have not been fully elucidated yet. In the current study, we have studied the immune response of different tissues to viral haemorrhagic septicaemia virus (VHSV) in rainbow trout fed with a non-supplemented control diet as well as in fish fed a commercial functional aquafeed (Protec™, Skretting) containing β-glucans, vitamin C, vitamin E and zinc. For this, after 30 days of feeding the fish with one of the two diets, they were subsequently infected with VHSV by bath or mock-infected. After 2 or 6 days post-infection, fish were sacrificed and the levels of transcription of different immune genes such as IgM, IgT, IgD, Mx, interferon γ (IFN γ) and perforin studied in different tissues (kidney, gut and gills). Additionally, the levels of natural IgMs in serum were also determined. Our results demonstrate that fish fed the functional diet were capable of mounting an increased IgM, IgT, IgD and Mx transcriptional response to the virus. Additionally, these fish also showed increased levels of natural IgMs in serum. These results reveal a previously undescribed effect of functional diets on fish Ig production and point to Protec™ as an adequate diet to be incorporated in holistic programs aimed at mitigating the effect of viral diseases.
L- methionine supplementation modulates IgM+ cell responses in rainbow trout.
(Frontiers Media, 2023-10-10) Martín, D; Ordás, MC; Carvalho, I; Díaz- Rosales, P; Núñez- Ortiz, N; Vicente- Gil, S; Arrogante, A; Zarza, C; Machado, M; Costas, B; Tafalla, C
The interest in dietary amino acids (AAs) as potential immunomodulators has been growing the recent years, since specific AAs are known to regulate key metabolic pathways of the immune response or increase the synthesis of some immune-related proteins. Methionine, tryptophan and lysine are among the ten essential AAs for fish, meaning that they cannot be produced endogenously and must be provided through the diet. To date, although dietary supplementation of fish with some of these AAs has been shown to have positive effects on some innate immune parameters and disease resistance, the effects that these AAs provoke on cells of the adaptive immune system remained unexplored. Hence, in the current study, we have investigated the effects of these three AAs on the functionality of rainbow trout (Oncorhynchus mykiss) IgM+ B cells. For this, splenic leukocytes were isolated from untreated adult rainbow trout and incubated in culture media additionally supplemented with different doses of methionine, tryptophan or lysine in the presence or absence of the model antigen TNP-LPS (2,4,6-trinitrophenyl hapten conjugated to lipopolysaccharide). The survival, IgM secreting capacity and proliferation of IgM+ B cells was then studied. In the case of methionine, the phagocytic capacity of IgM+ B cells was also determined. Our results demonstrate that methionine supplementation significantly increases the proliferative effects provoked by TNP-LPS and also up-regulates the number of cells secreting IgM, whereas tryptophan or lysine have either minor or even negative effects on rainbow trout IgM+ B cells. This increase in the number of IgM-secreting cells in response to methionine surplus was further verified in a feeding experiment, in which the beneficial effects of methionine on the specific response to anal immunization were also confirmed. The results presented demonstrate the beneficial effects of dietary supplementation with methionine on the adaptive immune responses of fish.