Chronic exposure to the parasite Enteromyxum leei (Myxozoa: Myxosporea) modulates the immune response and the expression of growth, redox and immune relevant genes in gilthead sea bream, Sparus aurata L

Fish Pathology Group, Department of Marine Species Biology, Culture and Pathology, Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas, Torre de la Sal, Ribera de Cabanes, Castellón, Spain.
Fish &amp Shellfish Immunology (Impact Factor: 2.67). 06/2008; 24(5):610-9. DOI: 10.1016/j.fsi.2008.01.014
Source: PubMed


The myxosporean parasite Enteromyxum leei invades the intestine of gilthead sea bream producing a slow-progressing disease, which may end in the death of fish. The present work aimed to better know the host immune response and the underlying molecular mechanisms, which may help to understand why some individuals seem to be refractory to the disease. Three main aspects involved in fish health and welfare (immune, growth and redox status) were studied in fish exposed to E. leei-contaminated effluent, in comparison with control animals (not exposed to the disease). After chronic exposure (113days), prevalence of infection was 67.8%. Among exposed fish, parasitized and non-parasitized fish exhibited clear differences in some of the measured innate immune factors (respiratory burst, serum peroxidases, lysozyme and complement), and in the expression of immune, antioxidant and GH-related genes. The respiratory burst of parasitized fish was significantly higher, and serum peroxidases and lysozyme were significantly decreased both in parasitized and non-parasitized fish. The gene expression of GHR-I, GHR-II, IGF-I and IGF-II was measured in head kidney (HK) samples, and that of interleukin (IL)-1beta, tumour necrosis factor (TNF)-alpha, alpha-2M, GR, GPx-1 and GRP-75 was measured in intestine and HK samples, by rtqPCR. Parasitized fish exhibited a down-regulation of IL-1beta, TNF-alpha and GPx-1 in the intestine, and GHR-I and IGF-I were also down regulated in HK. alpha-2M and GRP-75 were over-expressed in the intestine of parasitized animals. Non-parasitized fish had increased transcripts of GHR-I and IGF-I with respect to control animals, which could furnish their immunocytes with an advantage to combat the parasite. The expression of GHR-II and IGF-II was not altered by the parasite challenge.

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Available from: Alfonso Saera-Vila, Apr 15, 2015
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    • "Interestingly , the same lesion occurs in E. leei-infected sharpsnout sea bream (Diplodus puntazzo, Cetti) [60], a species that, as turbot, presents a high susceptibility to this myxozoan parasitosis, but not in diseased gilthead sea bream. In this sense, it is noteworthy to highlight that in E. leei-infected gilthead sea bream no significant differences in TNFa expression were found in blood or lymphohaematopietic organs (head kidney and spleen) at any time point (17 and 64 DPI in anal infection and 113 DPI in effluent infection) [34] [50]. In fact, all the changes found in the expression of cytokines were at the local intestinal level. "
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    ABSTRACT: Enteromyxum scophthalmi (Myxozoa) constitutes one of the most devastating pathogens for turbot (Scophthalmus maximus, L.) aquaculture. This parasite causes a severe intestinal parasitosis that leads to a cachectic syndrome with high morbidity and mortality rates for which no therapeutic options are available. Presence of inflammatory infiltrates, increased apoptotic rates and epithelial detaching have been described at intestinal level, as well as leukocyte depletion in lymphohaematopoietic organs. Previous investigations on enteromyxosis in turbot showed the high susceptibility of this species to the parasite and reported the existence of a dysregulated immune response against the parasite. The pleiotropic cytokine tumour necrosis factor alpha (TNFα) plays a major role in immune response and is involved in a wide range of biological activities. In teleost, the gene expression of this cytokine has been found regulated under several pathological conditions. Teleost TNFα shows some analogous functions with its mammalian counterparts, but the extent of its activities is still poorly understood. Cytokines are generally considered as a double-edge sword and TNFα has been implicated in the pathogenesis of different inflammatory diseases as well as in wasting syndromes described in mammals. The aim of this work was to analyse the expression of TNFα during enteromyxosis with molecular (Q-PCR) and morphological (immunohistochemistry) tools. Kidney, spleen and pyloric caeca from turbot with moderate and severe infections were analysed and compared to healthy naïve fish. TNFα expression was increased in both spleen and kidney in the earlier stages of the disease, whereas in severely infected fish, the expression decreased, especially in kidney. At the intestinal level, an increase in the number of TNFα-positive cells was noticed, which was proportional to the infiltration of inflammatory cells. The results demonstrate the involvement of TNFα in the immune response to E. scophthalmi in turbot, which could be related to the development of the clinic signs and lesions.
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    • "overcoming the invading pathogenic organism(s) and to deal with any foreign material until the acquired immune system is sufficiently activated [9] [10]. Many earlier studies have documented the expression levels of various immune-related genes in different fish models especially in response to various parasite infections such as Ichthyophthirius multifiliis [11], Trypanosoma carassii [12] and Enteromyxum leei [13]. The identification of L. calcarifer immunerelated genes upon challenge with bacterial lipopolysaccharide (LPS) was reported previously using the suppression subtractive hybridization (SSH) technique [14]. "
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    Fish &amp Shellfish Immunology 01/2013; 34(3). DOI:10.1016/j.fsi.2012.11.052 · 2.67 Impact Factor
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    • "Glucose-regulated protein 75, also named mortalin or mitochondrial HSP70, is one of the molecular chaperones representative of this cluster and their enhanced expression was coincident with the up-regulation of several mitochondrial ATP synthases, included in the same cluster. This finding is consistent with previous results analyzing the gene expression pattern of some target growth, redox and immune-relevant genes in the intestine of GSB [14]. The up-regulated expression of mortalin at the mRNA and protein level has also been observed in the liver tissue of GSB during both acute and chronic confinement stress [48], which emphasizes the relevance of this mitochondrial protein encoded by nuclear DNA as a stress biomarker in this fish species. "
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