Transforming growth factor-β1 expression in endangered age-0 shortnose suckers (Chasmistes brevirostris) from Upper Klamath Lake, OR relative to histopathology, meristic, spatial, and temporal data

Cytokine networks that suppress fish cellular immunity

Immunosuppressive cytokines are a class of cytokines produced by immune cells and certain non-immune cells that have a suppressive effect on immune function. Currently known immunosuppressive cytokines include interleukin (IL)-10, transforming growth factor beta (TGF-β), IL-35, and IL-37. Although latest sequencing technologies have facilitated the identification of immunosuppressive cytokines in fish, IL-10 and TGF-β were the most well-known ones that have been widely studied and received continuous attention. Fish IL-10 and TGF-β have been identified as anti-inflammatory and immunosuppressive factors, acting on both innate and adaptive immune systems. However, unlike mammals, teleost fish underwent a third or fourth whole-genome duplication event, which significantly expanded the gene family associated with the cytokine signaling pathway, making the function and mechanism of these molecules need further investigation. In this review, we summarize the advances of studies on fish immunosuppressive cytokines IL-10 and TGF-β since their identification, mainly focusing on production, signaling transduction, and effects on the immunological function. This review aims to expand the understanding of the immunosuppressive cytokine network in fish.

Effect of diet enriched with Agaricus bisporus polysaccharides (ABPs) on antioxidant property, innate-adaptive immune response and pro-anti inflammatory genes expression in Ctenopharyngodon idella against Aeromonas hydrophila

The effect of Agaricus bisporus polysaccharides (ABPs) supplemented diet on growth rate, antioxidant capacity, innate-adaptive immune response, proinflammatory and antiinflammatory genes expression in Ctenopharyngodon idella against Aeromonas hydrophila is reported. In both normal and challenged groups fed with 1.0 and 1.5 mg kg^-1 ABPs diets resulted in a significant weight gain and feed intake. The survival was 100% in normal fish fed without or with any ABPs diet; the challenged fish fed with 1.0 mg kg^-1 ABPs diet had 98.6% survival. The RBC and WBC counts, Hb, and Hct levels were significant in both normal and challenged groups fed with 1.0 and 1.5 mg kg^-1 ABPs diets. A significant increase in total protein and albumin level was observed in both groups fed with 1.0 and 1.5 mg kg^-1 ABPs diets. Significant increase in GPx, ROS, GR, GSH, PC, and MnSOD activity was observed in HK of both groups fed with 1.0 and 1.5 mg kg^-1 ABPs diets; similarly both groups when fed with the same ABPs diets showed significant Lz, C3, and C4 activity. However, both groups fed with 1.0 mg kg^-1 ABPs diet showed significant β-defensin, LEAP-2A, IL-6, and NF-κB P65 mRNA expression. Similarly, IFN-γ2, IL-10, and TNFα mRNA expressions were significant in both groups fed with 1.0 mg kg^-1 ABPs diet. The results indicate that both normal and challenged C. idella fed with a 1.0 mg kg^-1 ABPs diet had better growth, antioxidant status, immune response, and pro-anti-inflammatory gene modulation against A. hydrophila.

Effect of dietary astaxanthin administration on the growth performance and innate immunity of juvenile crucian carp (Carassius auratus)

The present study aims to explore the effects of oral astaxanthin administration on the growth performance and innate immunity of juvenile crucian carp (Carassius auratus). Juvenile crucian carps with a bodyweight of 40.06 ± 2.17 g were randomly assigned to four groups, i.e., one control group fed with a basic diet and three treatment groups fed with a diet that contains 200, 400 and 800 mg/kg astaxanthin. After 60 days of feeding, the groups fed with astaxanthin-containing diets had improved body weight gain rate; feed conversion ratio; intestinal digestive protease, lipase and amylase levels; serum superoxide dismutase, catalase, acid phosphatase, alkaline phosphatase and lysozyme activities; complement 3 and complement 4 levels; interleukin (IL)-10 and resistance to Aeromonas hydrophilia and reduced serum aspartate aminotransferase and alanine aminotransferase activities and tumour necrosis factor-α, IL-1β and IL-8 levels compared with those of the control group. Based on the efficiency of the oral administration of astaxanthin on the growth performance of juvenile crucian carps, the optimum dose of astaxanthin was 400 mg/kg. Results indicated that astaxanthin may be used as a dietary supplement for the crucian carp.

The growth performance and non-specific immunity of juvenile grass carp (Ctenopharyngodon idella) affected by dietary alginate oligosaccharide

The effects of alginate oligosaccharides (AOs) on the growth performance and non-specific immunity of juvenile grass carp (Ctenopharyngodon idella) were investigated by performing a 60-day feeding trial. Four trial diets were formulated and supplemented with different doses of AOs (0, 100, 200 and 400 mg/kg). Triplicate groups of grass carp were fed with one of the diets twice daily. The grass carps fed with diets containing an appropriate dose of AOs for 60 days exhibited higher survival rates; body weight gains; specific growth rates; resistance to Aeromonas hydrophila; superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase activities; and serum total protein, lysozyme, alkaline phosphatase, complement C3, complement C4 and interleukin-10 expression levels and lower feed conversion ratios and malondialdehyde, alanine aminotransferase, aspartate aminotransferase, IL-1β expression, IL-8 expression and tumor necrosis factor-α expression levels than the control group (p < 0.05). Based on the effects of AOs on growth performance and survival percent, the optimum dose of AOs was 200 mg/kg. Results indicate that AOs as a dietary supplement enhances the growth performance and non-specific immunity of grass carps and their resistance to diseases.

Dietary biotin deficiency decreased growth performance and impaired the immune function of the head kidney, spleen and skin in on-growing grass carp (Ctenopharyngodon idella)

The aim of this study was to investigate the effects of dietary biotin deficiency on the growth performance and immune function of the head kidney, spleen and skin in on-growing grass carp (Ctenopharyngodon idella). A total of 540 on-growing grass carp (117.11 ± 0.48 g) were fed six diets containing increasing levels of biotin (0.012, 0.110, 0.214, 0.311, 0.427 and 0.518 mg/kg diet) for 70 days. Subsequently, a challenge experiment was performed by infecting them with Aeromonas hydrophila for six days. Our results showed that compared with the appropriate biotin level, (1) biotin deficiency (0.012 mg/kg diet) reduced the activities of lysozyme (LZ) and acid phosphatase (ACP), decreased the contents of complement 3 (C3), C4 and immunoglobulin M (IgM), as well as reduced the mRNA levels of antimicrobial peptides in the head kidney, spleen and skin of on-growing grass carp; (2) biotin deficiency reduced the mRNA levels of anti-microbial substances: liver-expressed antimicrobial peptide (LEAP) -2A, LEAP-2B, hepcidin, β-defensin-1 and mucin 2 in the head kidney, spleen and skin of on-growing grass carp; (3) biotin deficiency increased the mRNA levels of pro-inflammatory cytokines interleukin 1β (IL-1β), IL-6, IL-8, IL-12p40, IL-15, IL-17D, tumour necrosis factor α (TNF-α) and interferon γ2 (IFN-γ2) partially in association with nuclear factor-kappa B (NF-κB) signalling and reduced anti-inflammatory IL-4/13A, IL-10, IL-11 and transforming growth factor β1 (TGF-β1) mRNA levels partially in association with target of rapamycin (TOR) signalling in the head kidney, spleen and skin of on-growing grass carp. Interestingly, biotin deficiency had no effect on the expression of IL-12p35, IL-4/13B, TGF-β2, 4E-BP1 (skin only) or IKKα in the head kidney, spleen and skin of on-growing grass carp. In conclusion, the results indicated that biotin deficiency impaired the immune function of the head kidney, spleen and skin in fish. Finally, based on the percent weight gain (PWG), the ability to prevent skin haemorrhages and lesions, the LZ activity in the head kidney and the C4 content in the spleen, the optimal dietary biotin levels for on-growing grass carp (117-534 g) were estimated as 0.210, 0.230, 0.245 and 0.238 mg/kg diet, respectively.

Serum biochemistry, liver histology and transcriptome profiling of bighead carp Aristichthys nobilis following different dietary protein levels

Dietary protein plays a major role in determining the rate of fish growth and overall health. Given that the liver is an important organ for metabolism and detoxification, we hypothesized that optimal dietary protein levels may benefit liver function. Herein, we investigated the effects of dietary protein level on serum biochemistry, liver histology and transcriptome profiling of juvenile bighead carp Aristichthys nobilis fed for 8 weeks on a diet supplemented with high protein (HP, 40%), low protein (LP, 24%) or optimal protein (OP, 32%; controls). The results revealed a significant change in liver morphology in LP and HP groups compared with the OP group, coupled with increased serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activity. RNA sequencing (RNA-Seq) analysis of the liver transcriptome yielded 47 million high-quality reads using an Illumina platform, which were de novo assembled into 80,777 unique transcript fragments (unigenes) with an average length of 1021 bp. Subsequent bioinformatics analysis identified 878 and 733 differentially expressed unigenes (DEGs) in liver in response to LP and HP diets, respectively. KEGG enrichment analysis of DEGs identified immune and metabolism-related pathways, including Toll-like receptor signaling, PI3K-Akt signaling, NF-κB signaling, complement and coagulation, peroxisome, nitrogen metabolism, PPAR signaling, and glycolysis and gluconeogenesis pathways. Transcriptome profiling results were validated by quantitative real-time PCR for 16 selected DEGs. The findings expand our understanding of the molecular mechanisms underlying the effects of dietary protein level on liver function in bighead carp.

Dietary protein levels regulated antibacterial activity, inflammatory response and structural integrity in the head kidney, spleen and skin of grass carp (Ctenopharyngodon idella) after challenged with Aeromonas hydrophila

This study investigated the effects of dietary protein levels on disease resistance, immune function and structural integrity in the head kidney, spleen and skin of grass carp (Ctenopharyngodon idella). A total of 540 grass carp (264.11 ± 0.76 g) were fed six diets containing graded levels of protein (143.1, 176.7, 217.2, 257.5, 292.2 and 322.8 g digestible protein kg^-1 diet) for 8 weeks. After the growth trial, fish were challenged with Aeromonas hydrophila for 14 days. The results indicated that optimal levels of dietary protein: (1) (1) increased the lysozyme (LA) and acid phosphatase (ACP) activities and the complement 3 (C3) and C4 contents, up-regulated antimicrobial peptides, anti-inflammatory cytokines, inhibitor of κBα, target of rapamycin and ribosomal protein S6 kinases 1 mRNA levels, whereas down-regulated pro-inflammatory cytokines, nuclear factor kappa B (NF-κB) P65, IKKβ, IKKγ, eIF4E-binding proteins (4E-BP) 1 and 4E-BP2 mRNA levels in the head kidney, spleen and skin of grass carp (P < 0.05), suggesting that optimal level of dietary protein could enhance immune function in the head kidney, spleen and skin of fish; (2) increased the activities and mRNA levels of antioxidant enzymes, enhanced the glutathione content, decreased reactive oxygen species, malondialdehyde (MDA) and protein carbonyl contents, and up-regulated the mRNA levels of NF-E2-related factor 2, B-cell lymphoma protein-2, inhibitor of apoptosis proteins, myeloid cell leukemia-1 and tight junction complexes, whereas down-regulated Kelch-like-ECH-associated protein (Keap) 1b, cysteinyl aspartic acid-protease 3, 8, 9, Fas ligand, apoptotic protease activating factor-1, Bcl-2 associated X protein and myosin light chain kinase mRNA levels in the head kidney, spleen and skin of grass carp (P < 0.05), indicating that optimal level of dietary protein could improve structural integrity in the head kidney, spleen and skin of fish. Finally, based on the skin hemorrhage and lesion morbidity, LA activity and MDA content, the optimal levels of dietary protein for grass carp (264 g-787 g) were estimated to be 241.45 g kg^-1 diet (217.68 g digestible protein kg^-1 diet), 301.68 g kg^-1 diet (265.48 g digestible protein kg^-1 diet) and 307.84 g kg^-1 diet (272.71 g digestible protein kg^-1 diet), respectively.

Effects of dietary protein levels on the disease resistance, immune function and physical barrier function in the gill of grass carp (Ctenopharyngodon idella) after challenged with Flavobacterium columnare

The effects of dietary protein levels on the disease resistance, gill immune function and physical barrier function of grass carp (Ctenopharyngodon idella) were investigated in this study. A total of 540 grass carp (264.11 ± 0.76 g) were fed six diets containing graded levels of protein (143.1, 176.7, 217.2, 257.5, 292.2 and 322.8 g digestible protein kg(-1) diet) for 8 weeks. After the growth trial, fish were challenged with Flavobacterium columnare for 3 days. The results indicated that optimal levels of dietary protein had the following effects: (1) the production of antibacterial components increased, and anti-inflammatory cytokines, inhibitor of κBα, target of rapamycin and ribosomal protein S6 kinases 1 mRNA levels were up-regulated, whereas mRNA levels of pro-inflammatory cytokines, nuclear factor kappa B (NF-κB) P65, NF-κB P52, IκB kinase (IKK) α, IKKβ, IKKγ, eIF4E-binding proteins (4E-BP) 1 and 4E-BP2 were down-regulated in the gills of grass carp (P < 0.05), indicating that fish gill immune function was enhanced at an optimal level of dietary protein; (2) the activities and mRNA levels of antioxidant enzymes and glutathione content increased, the contents of reactive oxygen species, malondialdehyde and protein carbonyl (PC) decreased, and NF-E2-related factor 2, B-cell lymphoma protein-2, inhibitor of apoptosis proteins, myeloid cell leukemia-1 and tight junction complexes mRNA levels were up-regulated, whereas Kelch-like-ECH-associated protein (Keap) 1a, Keap1b, cysteinyl aspartic acid-protease 3, 8, 9, fatty acid synthetase ligand, apoptotic protease activating factor-1, Bcl-2 associated X protein, c-Jun N-terminal protein kinase, myosin light chain kinase and p38 mitogen-activated protein kinase mRNA levels were down-regulated in the gills of grass carp (P < 0.05), indicating that the fish gill physical barrier function improved at an optimal level of dietary protein. Finally, based on the gill rot morbidity, ACP activity and PC content, the optimal levels of dietary protein for grass carp were estimated to be 286.65 g kg(-1) diet (253.73 g digestible protein kg(-1) diet), 290.46 g kg(-1) diet (257.76 g digestible protein kg(-1) diet) and 296.25 g kg(-1) diet (260.69 g digestible protein kg(-1) diet), respectively.