Fish and shellfish immunology reports最新文献

The abilities and ways in which organisms respond to stress have long been demonstrated to affect the immune response of the organism. In mammalian studies, researchers have observed that chronic/long-term stress has a pronounced immunosuppressive effect, while studies in acute stress have demonstrated some immunoenhansive properties. These dynamics have been somewhat conserved in fish, as the effects of cortisol and chronic stress on the fish immune system are distinctly immunosuppressive, however, acute stress mediated immunomodulation is still poorly understood. This review explores the lesser studied non-cortisol stress hormones relevant to acute stress, and how they affect the immune response in Fish. Additionally, the effects of acute stress on various innate immune parameters and the regulation of immune related transcripts are discussed. Subsequently, this review attempts to establish the temporal transition between acute and chronic stress in the context of immune mediation. The conclusions of this review suggest that the modulating effects acute stress has on fish immunity is significantly different than that of chronic stress, yet more focused research must be conducted to further elucidate the mechanisms in greater detail.

Previously a pattern recognition receptor (PRR) from kuruma shrimp was found able to recognize bacterial glycans by the C-type lectin domain (CTLD) and to interact with Jak/Stat receptor Domeless by the interleukin-like coiled coil (cc) region. In the current study, its homolog, namely Pc-ccCL, was found important in the antiviral response in red swamp crayfish Procambarus clarkii. This PRR plays a role by inhibiting white spot syndrome virus (WSSV) infection in a Jak/Stat dependent manner. The CTLD can bind the viral envelope protein VP28, while the cc region determines the dependence on Jak/Stat pathway. Two anti-lipopolysaccharides factors were identified as the downstream antiviral peptides. This study provides new insights into the antiviral signaling in invertebrates. Furthermore, the mechanism that a PRR recognizes virus and directly activates Jak/Stat pathway and antiviral-effector expression represents a simple but fast antiviral strategy in crustaceans.

Polyunsaturated fatty acids such as arachidonic and eicosapentaenoic acids are the precursors of eicosanoid metabolites (e.g prostaglandins and prostacyclins) which regulate inflammatory and immune response processes in fish organs. The present research studies the differential production of PGI₂, PGI₃, PGE₂ and PGE₃ by primary liver and head kidney cells isolated from salmon and challenged with single or combined ARA and/or EPA. There was a significant increase in the production of PGE₂ and PGI₃ in both types of cells after exposure to single and combined fatty acids. Increased production of PGE₃ was only detected in liver cells after exposure to ARA+EPA. The levels of PGI₂ in liver cells were significantly increased after exposure to all the tested fatty acid systems, while the production levels in head kidney cells were only significant after exposure to ARA or ARA+EPA, but not to EPA, where the production was non-significantly decreased compared to the control cells. In general, liver cells synthetized higher prostaglandin levels than prostacyclins, and the opposite was observed in head kidney cells, which synthetized highly remarkable amounts of prostacyclin compared to liver cells. The overall production for both types of cells and various fatty acid systems were characterized by a high proportion of the omega-3 fatty acid metabolites (PGE₃+PGI₃) compared to the omega-6 counterpart (PGE₂+PGI₂). Some potential production mechanisms are proposed and comprehensively discussed. The results of the present research are the first to deliver the differential production of prostacyclins and prostaglandins by liver and head kidney cells from salmon, thereby paving the way for understanding the significance of these prostanoids in fish physiology and disease.

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.

CD40 and CD154 are one of the best-characterized costimulatory molecules essential for adaptive immunity, which extensively involved in T and B cell activation, IgM Ab production, isotype class switching, germinal center formation and affinity maturation. However, the functionality of CD40 and CD154 in IgZ-mediated immunity remains limited. In this study, we explored the regulatory role of Cd40-Cd154 interaction in IgZ-mediated antibacterial immunity in zebrafish. The results showed that the IgZ-mediated antibacterial response can be significantly induced in response to A. hydrophila infection. The percentage of Cd40⁺IgZ⁺ B cells and the production of IgZ Ab were substantially increased upon A. hydrophila stimulation, but these reactions were markedly declined in Cd154 blockade fish by administering anti-Cd154 Ab or recombinant sCd40-Ig protein, accompanied with the impairment of the vaccine-initiated IgZ-mediated immunoprotection of fish against A. hydrophila infection. These observations suggested the essential role of Cd40-Cd154 interaction in IgZ-mediated bacterial immunity. Notably, the Cd40 and Cd154 costimulatory signals are required for a TD antigen-induced IgZ immunity, but are not indispensable for a TI antigen-induced IgZ immune response. These findings indicated the differential role of Cd40-Cd154 interaction in bacterial TD and TI antigen-induced IgZ immunity, which suggested the existence of diverse regulatory mechanisms underlying IgZ-mediated antibacterial immune reactions. To our knowledge, this is the first report to show the functional role of Cd40-Cd154 costimulatory signaling pathway in IgZ-mediated immune defense against bacterial infection. We hope this study will improve the current understanding of the coevolution between the IgZ/IgT immunoglobins and CD40/CD154 costimulatory molecules.

A new cell line was isolated and characterized from the head kidney of Siganus fuscescens (rabbit fish). The new macrophagic-like cell line was named as rabbit fish macrophage (RFM), and which could be sub-cultured for over 50 cycles since the development. RFM cell line was tested for growth in different temperatures and serum concentrations: the best growing condition was optimized at 20% serum under 28 °C. In cultured RFM cells, sequencing of 18S rRNA, as well as immunostaining of cytokeratin and CD 68, confirmed the identity as macrophagic cell of S. fuscescens. Cultured RFM cells were exposed to challenge of inflammation, as triggered by LPS, showing highly sensitive responses to inflammation, including release of nitric oxide, expression of cytokine, and activation of phagocytosis. The water extract of aerial part of Scutellaria baicalensis, named as SBA, has been shown anti-inflammatory property in S. fuscescens fish. In order to extend the application of SBA in aquaculture, the extract and its effective flavonoids, i.e. baicalin and scutellarin, were applied in LPS-treated RFM cells. Application of SBA extract, baicalin or scutellarin, inhibited the expressions of LPS-induced inflammatory cytokines, i.e. IL-1β, TNF-α, as well as the signaling of transcription factor NF-κB. The results support the established RFM cell line could be an ideal in vitro model in drug screening relating to inflammation. Additionally, the notion of SBA herbal extract in fish aquaculture is supported by its efficacy against inflammation.

Interleukin-2 (IL-2) signals influence various lymphocyte subsets during differentiation, immune responses and homeostasis. IL-2 acts on different cells by binding to its receptors (IL-2R), which consists of three subunits, IL-2Rα (CD25), IL-2Rβ (CD122), and the common gamma chain or γc (CD132). In the present study, three IL-2 receptor subunits, designated as LcCD25-like (LcCD25L), LcIL-2Rβ and Lcγc, were characterized in large yellow croaker (Larimichthys crocea). The LcCD25L, like other teleost CD25L or IL-2/IL-15Rα, contains only one sushi domain at N-terminus. The synteny of CD25L from different teleost are conserved. The deduced protein of LcIL-2Rβ and Lcγc exhibits a typical class I cytokine receptors architecture, including a cytokine-binding homology domain (CHD) consisting of two fibronectin type-III (FNIII) domains (D1 and D2) and a conserved WSXWS motif in D2 domain. These three IL-2 receptor subunits were constitutively expressed in all tissues and primary immune-related cells examined. The LcCD25L was highly expressed in blood, while LcIL-2Rβ and Lcγc were highly expressed in spleen and gill. For immune-related cells, LcCD25L and LcIL-2Rβ were highly expressed in PKLs, while the Lcγc exhibited the highest expression in PKMs. These three IL-2 receptor subunits could be dramatically induced by T cell mitogen PHA in PKLs, which mainly composed of T and B lymphocytes. The results presented indicated that large yellow croaker IL-2R might exercise function on lymphocytes, especially on activated T cells.

Immunomodulation is one of the useful tools to prevent diseases in aquaculture. In this study, the immunomodulatory effects of vitamin-E (100 mg/kg feed) and commercial probiotic consortia, Rhodomax™ (5 g/kg feed) on the innate immunity of Labeo rohita and their protective effect against Aeromonas hydrophila infection were evaluated and compared. Three groups of fish at 30 numbers/tank were fed with vitamin-E, probiotic and control diets at 3% body weight for 30 days, in triplicate. Following this, the fish of all groups were injected intramuscularly with A. hydrophila N₁₀P at 2.40 × 10⁷ cells/fish. The growth indices like specific growth rate (SGR) and feed conversion ratio (FCR) during the feeding and the non-specific immune responses during the feeding and post-challenge regimen were recorded. The dietary supplementation of vitamin-E and/or commercial probiotics caused significant improvements in the innate immunity of L. rohita compared to control. Nevertheless, the vitamin-E diet offered markedly better results in terms of SGR, FCR, ceruloplasmin, antiprotease, myeloperoxidase and phagocytic activities of L. rohita during the feeding and post-challenge regimen. While the respiratory oxidative burst activity was enhanced in probiotic diet-fed L. rohita only during the feeding regimen. All the immune parameters reached normalcy on day 15 post-injection with A. hydrophila. These findings revealed that supplementation vitamin-E at 100 mg/kg feed may improve the growth indices, prime the non-specific immune responses of L. rohita against A. hydrophila infection and enhance the overall health status than the tested commercial probiotics.