Fish and shellfish immunology reports最新文献

Chemically-induced models of intestinal inflammation are a useful tool for the study of immune responses and inflammation. Although well established in mammals, application of these models is currently limited in teleosts. Based on a variety of factors, including genetic diversity, known toxicological sensitivity, and economic importance, we propose salmonids as a model family of fishes for studying intestinal inflammation. We present a rainbow trout model of chemically-induced intestinal inflammation using 2,4,6-trinitrobenzene sulfonic acid (TNBS), assessed through histological analysis of primary and secondary intestinal folding, enterocyte morphology, goblet cell size and frequency, tissue layer thickness, and immune cell infiltration. Twenty-four hours after treatment with one of three concentrations of TNBS, trout developed classic signs of intestinal inflammation, including notably increased thickness of primary and secondary folds, and increased immune cell infiltration as compared to controls. This study provides a simple, reproducible model of rapid TNBS-induction of moderate intestinal inflammation.

Lysozyme is an important immune effector in innate immunity against pathogen infection. But the study on the active region of lysozyme is limited. In this study, two highly homologous lysozymes were identified from crayfish (designated as PcLysi4 and PcLysi5). The molecular structures of PcLysi4 and PcLysi5 were predicted by SWISS-MODEL with the structure of lysozyme (PDB accession No. 4PJ2.2.B) as model. The results suggested that the structure of PcLysi4 and PcLysi5 were highly similar, but there were more α-helices at positions (127–139) and longer β-sheet at positions (49–57) in the structure of PcLysi5 than in that of PcLysi4. The antibacterial and antiviral functions of the two lysozymes were investigated. PcLysi4 and PcLysi5 could promote the bacterial clearance ability of crayfish, and increase the survival rate of Vibrio-infected crayfish. Further study showed that PcLysi5 inhibited WSSV replication, and enhanced the survival rate of WSSV-infected crayfish. There was no evidence that PcLysi4 has an influence on WSSV replication. Furthermore, PcLysi5 was detected to interact with envelope protein VP24 of WSSV. Our results would provide a new reference for the study on active region of lysozyme.

As an important pattern-recognition receptor (PRR), C-type lectins (CTLs) play significant roles in recognizing microbes and battle against pathogenic microorganism in innate immunity. In this study, two tandem threonine containing CTLs (designated as EcThr-LecA and EcThr-LecB) were identified from Exopalaemon carinicauda. The full-length cDNA of EcThr-LecA and EcThr-LecB consisted of 1521 and 1518 bp with 1251 and 1242 bp open reading frame encoding a protein with 412 and 413 amino acids, respectively. The genome structure of EcThr-LecA included 10 exons and 9 introns, and the sequences of intron6 and intron7 were variable. The nucleotide sequence of intron2 in EcThr-LecB was specific and different with that of EcThr-LecA. EcThr-LecA and EcThr-LecB proteins were predicted to have a signal peptide, two conserved carbohydrate recognition domain (CRD), and tandem threonine region. The expression levels of EcThr-LecA and EcThr-LecB in the intestine were significantly up-regulated after Vibrio parahaemolyticus and white spot syndrome virus (WSSV) challenge. RNA interference (RNAi) was used to explore the effects of EcThr-LecB silencing on the mRNA expression of anti-lipopolysaccharide factor (ALF), crustin (CRU), and lysozyme (LYSO). Knock down of EcThr-LecB could evidently down-regulate the expression of eight different antibacterial peptides (AMPs), including EcALF2, EcCRU1, EcCRU3, EcCRU4, EcLYSO1, EcLYSO2, EcLYSO3, and EcLYSO4, whereas make no effect on the transcription of EcALF1, EcALF3, EcCRU2, and EcLYSO5. The recombinant two CRD domains and tandem threonine region (RLecB) of EcThr-LecB could bind diverse bacteria, lipopolysaccharide, and peptidoglycans in vitro. In addition, RLecB could accelerate the clearance of V. parahaemolyticus in vivo. The present data indicated that new-found tandem threonine containing CTLs in E. carinicauda may act as PRR to participate in the innate immune defense against pathogens by the recognition of non-self, regulation of AMPs, and clearance of invaders.

The host immune system tends to reject xenogenic-implanted cells making tumor development in adult host animal models difficult. Immune system suppression is used for successful xenotransplantation of human cancer cells in many animal models. The studies of cancer development processes in vivo offer opportunities to understand cancer biology and discover new therapeutic strategies. In this context, zebrafish is a model that has been widely applied in the study of human diseases, such as cancer. However, the long-term immunosuppression of these adult zebrafish is still under study as a xenograft animal model for human cancer. This work aimed to evaluate the effects of 21 days of (long-term) exposure of dexamethasone in zebrafish-transplanted with MGSO-3 cells, human breast tumor cell line. Our results show that the animals, while kept on dexamethasone treatment, remained with a 50% reduction in the number of peripheral lymphocytes. In vitro data demonstrated that up to 7 days of dexamethasone treatment did not alter the morphology, proliferation, or viability of MGSO-3 cells. The animals that received a prolonged dexamethasone treatment allowed the engraftment of tumor cells in 100% of the zebrafish tested. These animals also showed tumor progression over 21 days. The experimental group that received only previous exposure to dexamethasone had their tumors regressed after 14 days. In conclusion, the prolonged use of dexamethasone in zebrafish showed a potential strategy for in vivo monitoring of xenograft tumor growth for development studies, as well as in anticancer drug discovery.

RNA interference (RNAi) is a conservative and important functional pathway in eukaryocyte. It regulates the expression of genes that are engaged in a variety of cellular physiological functions. Among the functions of RNAi, its antiviral function have attracted many attentions.The RNAi pathway molecules are able to recognize virus-related dsRNA and degrade it, therefore killing the virus. More importantly, RNAi could mediate systemic antiviral responses, transmit from cell to cell, and systemic RNA interference defective 1 (SID1) was thought to play an important role in this process. In the present study, a SID1 gene (LvSID1) of Litopenaeus vannamei was cloned. LvSID1 could locate to both plasma membrane and endoplasmic reticulum. Result of real-time RT-PCR assay showed that it was highly expressed in shrimp gills. Besides, it was shown that over-expressed LvSID1 in Sf9 cells could significant enchane RNAi efficiency. It was found that the expression of LvSID1was regulated by white spot syndrome virus (WSSV), and knockdown expression of LvSID1 increased the cumulative mortality of WSSV infection shrimp. These results suggested that LvSID1 likely to played a role in L. vannamei systemic RNAi, and was involved in WSSV resistence.

Endotoxin, the outer cell wall membrane lipopolysaccharide component of the Gram-negative bacteria is a factor responsible for a number of complications/disorders and plays important role in the associated with pathophysiological complications and pathogenesis of many diseases in animals. Unlike higher animals which are extremely sensitive to endotoxin, fish are found to be resistant to endotoxic shock and earlier studies though limited have demonstrated the patho-physiological, immuno-endocrinological and immuno-neurological effects of LPS/endotoxin in aquatic animals including fish. Herein in the present investigation, the effect of pure endotoxin on immuno-haematological parameters of stinging catfish, Heteropneustes fossilis ranging from 50–60 g was studied by intraperitoneally injecting 0.1, 0.05 and 0.01 mg endotoxin per fish. H. fossilis yearlings were found to resist the endotoxin concentration up to 0.1 mg without any mortality. While, no change in immune parameters was recorded in stinging catfish injected with low dose of endotoxin (0.01 mg), most of the immune parameters were found to be significantly elevated in catfish injected with 0.05 mg endotoxin. Different serum and immune parameters like protein, globulin, lysozyme, respiratory burst activity, myeloperoxidase activity, natural agglutination titre were found to be significantly high (p < 0.01) at a dose of 0.05 mg endotoxin per fish. On the contrary, most of these parameters were decreased at high dose i.e., 0.1 mg endotoxin per fish, thereby indicating the immuno-suppressive effect of the endotoxin. The findings of the modulation of innate immunity also corroborated with the results of Aeromonas hydrophila pathogen challenge study with highest percent of mortality in group injected with 0.1 mg endotoxin per fish and least percentage in group injected with 0.05 mg endotoxin per fish.

Probiotics application in aquaculture could be a key solution to enhance the overall immune and growth indicators of cultured fish. Several bacteria have demonstrated encouraging results as probiotics for fish. The current study evaluated the possible effects of Zado® (Ruminococcus Flavefaciens 28 × 10⁴ CFU) dietary incorporation at 1 and 2 g/kg diet for 6-weeks on growth, hematological profile, immune performance, the biochemical, and anti-oxidative profiles of Oreochromis niloticus. Sampling was performed at the end of the third and sixth week. Fish fed with Zado® enriched diets showed (P < 0.05) significantly improved hematologic (MCHC, MCH, MCV, and PCV and RBCs count) and leukocytic readings (WBCs, monocytes and lymphocytes). The immune (phagocytosis, lysozyme U/ml, and nitric oxide pmol/ml) parameters were (P < 0.05) markedly increased in Zado® incorporated groups. Biochemical parameters (globulin, albumin and total proteins; AST and ALT) levels showed significant (P < 0.05) improvement at three and six weeks in Zado® groups. Serum glucose concentration was significantly higher in Zado® groups at three weeks, while was only higher for 2 g/kg Zado® at six weeks. Also, cortisol level was lower in both Zado® groups at three weeks, while was only lower for 1 g/kg Zado® at six weeks. In addition, antioxidants Gpx, SOD, and CAT were (P < 0.05) significantly higher in Zado® treatments, while pro-oxidant MDA was (P < 0.05) significantly decreased. Moreover, growth performance was also (P < 0.05) markedly boosted in Zado® incorporated groups compared to the control. Conclusively, our results demonstrated that Zado® probiotic is a safe alternative for O. niloticus with beneficial effects on hematological parameters, immune, biochemical, antioxidants, and growth profiles.

Thrombospondins (TSPs) are extracellular, calcium-binding glycoproteins that play an essential role in cell homeostasis and development, wound-healing, angiogenesis, connective tissue organization, immune response etc. and it conserves from sea sponges to mammals. However, their role in shrimp immunity is poorly understood. In the present study, the differential expression profiling of TSP transcripts in Penaeus monodon tissues such as gills, lymphoid organs, hepatopancreas, and hemolymph challenged with white spot syndrome virus (WSSV), were studied by quantitative real-time PCR. Further, shrimps fed with the immunostimulant (β-glucan) when challenged with WSSV showed significant upregulation of TSP expression in gills, hepatopancreas, and lymphoid organ at the early phase of WSSV infection. The results suggest that TSP may be an inducible acute phase response protein to WSSV infection. The possibility of differences in mRNA expression pattern seen in immunostimmulated shrimp after the viral challenge, possibility due to altered immune mechanisms getting triggered during immunostimulant administration and virus infections in the host.

Aquaculture production has increased in the last decades, with crustacean production contributing with 9.8% of the total production. However, fisheries and aquaculture sectors present several challenges, such as fish stocks fished beyond biological sustainability, animal diseases, biosecurity, and environmental impact. It is important to improve shrimp production with healthy animals, avoiding environmental impacts, e.g. with the use of heterotrophic rearing system. It is known that the heterotrophic system can stimulate the activation of immune genes, but how it affects the shrimp immune system is unknown. To assess if a heterotrophic system influences the cellular immune response in shrimp, Litopenaeus vannamei shrimp were reared in heterotrophic and clear water systems. Cellular immune response parameters such as total and differential hemocyte counts, phagocytosis indices and the production of the superoxide anion were evaluated after 60, 120 and 180 days. After 60 days, total haemocyte counts were higher in shrimps reared in the clear water system, while after 120 days it was higher in shrimps reared in the heterotrophic system. No significant difference was observed after 180 days. Hyaline, granular and semi-granular cells showed similar behavior, peaking after 120 days in the heterotrophic system. By the 60th day, phagocytic capacity was higher in the heterotrophic system, while no differences were found for the 120th and 180th day. No differences were detected concerning the phagocytic index or superoxide anion production. The heterotrophic system can affect total and differential shrimp haemocyte counts and phagocytic capacity, depending on the period of time they were maintained in this system. However, the phagocytic index and superoxide anion production are not affected by the heterotrophic system at the time points evaluated herein.