RESUMEN
Various types of professional immune cells first emerge in fish and likely represent the primordial form and functions. Recent advancements revealed the direct connection between the central nervous system and the immune system in the mammalian brain. However, the specifics of brain-immune networks in the fish and the underlying mechanisms of teleost's brain against pathogen infection have not been fully elucidated. In this study, we investigated the distribution of markers representing cerebral cells associated with protection and professional lymphocytes in the seven major components of the Nile tilapia brain through RNA-Seq assay and observed the most dominant abundance in the medulla oblongata. The subsequent challenge test revealed the non-specific cytotoxic cells (NCCs) exhibited the strongest response against streptococcal infection of the brain. The presence of NCCs in the brain was then confirmed using immunofluorescence and the cytotoxic effects usually induced by NCCs under infection were determined as well. Collectively, these findings contribute significantly to comprehending the mechanism of fish neuroimmune interaction and enhancing our understanding of its evolutionary development.
Asunto(s)
Enfermedades de los Peces , Bulbo Raquídeo , Infecciones Estreptocócicas , Streptococcus agalactiae , Animales , Infecciones Estreptocócicas/inmunología , Infecciones Estreptocócicas/microbiología , Streptococcus agalactiae/inmunología , Streptococcus agalactiae/fisiología , Enfermedades de los Peces/inmunología , Enfermedades de los Peces/microbiología , Bulbo Raquídeo/inmunología , Encéfalo/inmunología , Encéfalo/microbiología , Tilapia/inmunología , Tilapia/microbiología , Cíclidos/inmunología , Cíclidos/microbiologíaRESUMEN
Heme oxygenase-1 (HO-1), an inducible rate-limiting metabolic enzyme, exerts critical immunomodulatory functions by potential anti-oxidant, anti-inflammatory, and anti-apoptotic activities. Although accumulative studies have focused on the immune functions of HO-1 in mammals, the roles in fish are poorly understood, and the reports on involvement in the defensive and immune response are very limited. In this study, On-HO-1 gene from Oreochromis niloticus was successfully cloned and identified, which contained an open reading frame (ORF) of 816 bp and coded for a protein of 271 amino acids. The On-HO-1 protein phylogenetically shared a high homology with HO-1 in other teleost fish (76.10%-98.89 %) and a lowly homology with HO-1 in mammals (38.98%-41.55 %). The expression levels of On-HO-1 were highest in the liver of healthy tilapias and sharply induced by Streptococcus agalactiae or Aeromonas hydrophila. Besides, On-HO-1 overexpression significantly increased non-specific immunological parameters in serum during bacterial infection, including LZM, SOD, CAT, ACP, and AKP. It also exerted anti-inflammatory and anti-apoptotic effects in response to the immune response of the infection with S. agalactiae or A. hydrophila by upregulating anti-inflammatory factors (IL-10, TGF-ß), autophagy factors (ATG6, ATG8) and immune-related pathway factors (P65, P38), and down-regulating pro-inflammatory factors (IL-1ß, IL-6, TNF-α), apoptotic factors (Caspase3, Caspase9), pyroptosis factor (Caspase1), and inflammasome (NLRP3). These results suggested that On-HO-1 involved in immunomodulatory functions and host defense in Nile tilapia.
Asunto(s)
Aeromonas hydrophila , Cíclidos , Enfermedades de los Peces , Proteínas de Peces , Infecciones por Bacterias Gramnegativas , Hemo-Oxigenasa 1 , Inmunidad Innata , Filogenia , Animales , Cíclidos/inmunología , Cíclidos/genética , Enfermedades de los Peces/inmunología , Proteínas de Peces/genética , Proteínas de Peces/inmunología , Proteínas de Peces/química , Aeromonas hydrophila/fisiología , Inmunidad Innata/genética , Hemo-Oxigenasa 1/genética , Hemo-Oxigenasa 1/inmunología , Infecciones por Bacterias Gramnegativas/inmunología , Infecciones por Bacterias Gramnegativas/veterinaria , Infecciones Estreptocócicas/inmunología , Infecciones Estreptocócicas/veterinaria , Streptococcus agalactiae/fisiología , Regulación de la Expresión Génica/inmunología , Perfilación de la Expresión Génica/veterinaria , Alineación de Secuencia/veterinaria , Secuencia de AminoácidosRESUMEN
In the present study, 59 autochthonous bacteria were isolated from the intestine of tilapia. Following enzyme producing activity, antagonistic ability, hemolytic activity, drug sensitivity assessments, and in vivo safety evaluation, 7 potential probiotic strains were screened out: Bacillus tequilensis BT0825-2 (BT), Bacillus aryabhattai BA0829-3 (BA1), Bacillus megaterium BM0505-6 (BM), Bacillus velezensis BV0505-11 (BV), Bacillus licheniformis BL0505-18 (BL), B. aryabhattai BA0505-19 (BA2), and Lactococcus lactis LL0306-15 (LL). Subsequently, tilapia were fed basal diets (CT) and basal diets supplemented with 108 CFU/g of BT, BA1, BM, BV, BL, BA2 and LL, respectively. After 56 days of continuous feeding, the growth parameters (weight gain, final weight, and specific growth rate) showed significant improvement (p < 0.05) in both BM and BA2 groups. The total cholesterol and triglycerides of serum were significantly decreased in BV and LL groups (p < 0.05). The superoxide dismutase, glutathione reductase, and lysozyme of BV, BA2 and LL groups were increased, and the malondialdehyde of BV group was significantly decreased. The villous height and amylase of midgut were increased in BV, BA2 and LL groups. In addition, the expression levels of ZO-1 and occludin genes in the midgut of tilapia were enhanced in BM, BV, BA2 and LL groups. The supplementation of probiotics reduced the abundance of Cyanobacteria and increased the abundance of Actinobacteria at the phylum level. At the genus level, the addition of probiotics increased the abundance of Romboutsia. Furthermore, improvement in the expression of immune-related genes were observed, including interleukin 1ß, interleukin 10, tumor necrosis factor alpha, and transforming growth factor beta (p < 0.05). After challenging with S. agalactiae, the survival rates of BV, BA2 and LL groups were significantly higher than CT group (p < 0.05). Above results indicated that BM, BA2, BV and LL improved growth performance, gut health or immunity of tilapia, which can be applied in tilapia aquaculture.
Asunto(s)
Alimentación Animal , Cíclidos , Resistencia a la Enfermedad , Enfermedades de los Peces , Probióticos , Infecciones Estreptocócicas , Streptococcus agalactiae , Animales , Probióticos/administración & dosificación , Probióticos/farmacología , Streptococcus agalactiae/fisiología , Cíclidos/inmunología , Cíclidos/crecimiento & desarrollo , Infecciones Estreptocócicas/veterinaria , Infecciones Estreptocócicas/inmunología , Enfermedades de los Peces/inmunología , Enfermedades de los Peces/microbiología , Alimentación Animal/análisis , Resistencia a la Enfermedad/efectos de los fármacos , Dieta/veterinaria , Intestinos/microbiología , Intestinos/inmunología , Microbioma Gastrointestinal/efectos de los fármacos , Inmunidad Innata/efectos de los fármacos , Bacillus/química , Bacillus/fisiología , Distribución AleatoriaRESUMEN
OBJECTIVES: The aim of this study was to quantify and identify metabolites of Ice Nucleation Active (INA) bacteria as an anti-biofilm agent against biofilms of fish pathogens such as Aeromonas hydrophila and Streptococcus agalactiae. RESULTS: Ice nucleation active bacteria, which have the ability to catalyze ice nucleation, isolated from rainwater in previous studies, were used. All INA isolates were tested in several assays, including the antimicrobial test, which uses streptomycin as the positive control and none of the isolates were found positive in the antimicrobial test. As for the quorum quenching assay, it was found that four out of ten isolates were able to disturb the communication system in Chromobacterium violaceum wild type, which was used as the indicator bacteria. On the next assay, all ten isolates were tested for Biofilm Inhibition and Destruction and showed anti-biofilm activity with the highest percentage inhibition of 33.49% by isolate A40 against A. hydrophila and 77.26% by isolate A19 against S. agalactiae. C1 performed the highest destruction against A. hydrophila and S. agalactiae, with percentages of 32.11% and 51.88%, respectively. As for the GC-MS analysis, supernatants of INA bacteria contain bioactive compounds such as sarcosine and fatty acids, which are known to have antibiofilm activity against several biofilm-forming bacteria. Through 16s rRNA sequencing, identified bacteria are from the Pantoea, Enterobacter, and Acinetobacter genera. As for the conclusion, ice nucleation active bacteria metabolites tested showed positive results against pathogenic bacteria Aeromonas hydrophila and Streptococcus agalactiae in destructing and inhibiting biofilm growth.
Asunto(s)
Aeromonas hydrophila , Antibacterianos , Acuicultura , Biopelículas , Streptococcus agalactiae , Biopelículas/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Aeromonas hydrophila/efectos de los fármacos , Aeromonas hydrophila/fisiología , Streptococcus agalactiae/efectos de los fármacos , Streptococcus agalactiae/fisiología , Antibacterianos/farmacología , Acuicultura/métodos , Enfermedades de los Peces/microbiología , Animales , ARN Ribosómico 16S/genética , Pruebas de Sensibilidad Microbiana , Infecciones por Bacterias Gramnegativas/microbiología , Infecciones por Bacterias Gramnegativas/tratamiento farmacológico , Hielo , Infecciones Estreptocócicas/microbiología , Infecciones Estreptocócicas/tratamiento farmacológico , Percepción de Quorum/efectos de los fármacosRESUMEN
Bacterial ClpB is an ATP-dependent disaggregate that belongs to the Hsp100/Clp family and facilitates bacterial survival under hostile environmental conditions. Streptococcus agalactiae, which is regarded as the major bacterial pathogen of farmed Nile tilapia (Oreochromis niloticus), is known to cause high mortality and large economic losses. Here, we report a ClpB homologue of S. agalactiae and explore its functionality. S. agalactiae with a clpB deletion mutant (∆clpB) exhibited defective tolerance against heat and acidic stress, without affecting growth or morphology under optimal conditions. Moreover, the ΔclpB mutant exhibited reduced intracellular survival in RAW264.7 cells, diminished adherence to the brain cells of tilapia, increased sensitivity to leukocytes from the head kidney of tilapia and whole blood killing, and reduced mortality and bacterial loads in a tilapia infection assay. Furthermore, the reduced virulence of the ∆clpB mutant was investigated by transcriptome analysis, which revealed that deletion of clpB altered the expression levels of multiple genes that contribute to the stress response as well as certain metabolic pathways. Collectively, our findings demonstrated that ClpB, a molecular chaperone, plays critical roles in heat and acid stress resistance and virulence in S. agalactiae. This finding provides an enhanced understanding of the functionality of this ClpB homologue in gram-positive bacteria and the survival strategy of S. agalactiae against immune clearance during infection.
Asunto(s)
Enfermedades de los Peces , Chaperonas Moleculares , Infecciones Estreptocócicas , Streptococcus agalactiae , Estrés Fisiológico , Animales , Ratones , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Cíclidos , Enfermedades de los Peces/microbiología , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Células RAW 264.7 , Infecciones Estreptocócicas/veterinaria , Infecciones Estreptocócicas/microbiología , Streptococcus agalactiae/fisiología , Streptococcus agalactiae/patogenicidad , Streptococcus agalactiae/genética , VirulenciaRESUMEN
Non-specific cytotoxic cells (NCCs) are vital immune cells involved in teleost's non-specific immunity. As a receptor molecule on the NCCs' surface, the non-specific cytotoxic cell receptor protein 1 (NCCRP-1) is known to play a crucial role in mediating their activity. Nevertheless, there have been limited studies on the signal molecule that transmits signals via NCCRP-1. In this study, a yeast two-hybrid (Y2H) library of tilapia liver and head kidney was constructed and subsequently screened with the bait vector NCCRP-1 of Oreochromis niloticus (On-NCCRP-1) to obtain a C-type lectin (On-CTL) with an interacting protein sequence. Consequently, the full-length sequence of On-CTL was cloned and analyzed. The expression analysis revealed that On-CTL is highly expressed in the liver and is widely distributed in other tissues. Furthermore, On-CTL expression was significantly up-regulated in the brain, intestine, and head kidney following a challenge with Streptococcus agalactiae. A point-to-point Y2H method was also used to confirm the binding between On-NCCRP-1 and On-CTL. The recombinant On-CTL (rOn-CTL) protein was purified. In vitro experiments demonstrated that rOn-CTL can up-regulate the expression of killer effector molecules in NCCs via its interaction with On-NCCRP-1. Moreover, activation of NCCs by rOn-CTL resulted in a remarkable enhancement in their ability to eliminate fathead minnow cells, indicating that rOn-CTL effectively modulates the killing activity of NCCs through the NCC receptor molecule On-NCCRP-1. These findings significantly contribute to our comprehension of the regulatory mechanisms governing NCC activity, paving the way for future research in this field.
Asunto(s)
Cíclidos , Enfermedades de los Peces , Proteínas de Peces , Lectinas Tipo C , Streptococcus agalactiae , Animales , Cíclidos/inmunología , Cíclidos/genética , Lectinas Tipo C/genética , Lectinas Tipo C/inmunología , Lectinas Tipo C/química , Proteínas de Peces/genética , Proteínas de Peces/inmunología , Enfermedades de los Peces/inmunología , Streptococcus agalactiae/fisiología , Infecciones Estreptocócicas/inmunología , Infecciones Estreptocócicas/veterinaria , Regulación de la Expresión Génica/inmunología , Secuencia de Aminoácidos , Inmunidad Innata/genética , Alineación de Secuencia/veterinaria , Filogenia , Perfilación de la Expresión Génica/veterinariaRESUMEN
Streptococcosis, the most common bacterial disease of fish in recent years, is highly infectious and lethal, and has become an important factor hindering the healthy and sustainable development of aquaculture. Chicken egg yolk antibody (IgY) has the advantages of high antigen specificity, inexpensive and easy to obtain, simple preparation, no toxic side effects, and in line with animal welfare, which is a green and safe alternative to antibiotics. In this study, the potential of specific IgY in the treatment of gastrointestinal pathogens was explored by observing the effects of specific IgY on intestinal flora, pathological tissue, apoptosis, oxidative stress, and inflammatory response of tilapia. We used the specific IgY prepared in the early stage to feed tilapia for 10 days, and then the tilapia was challenged with Streptococcus agalactiae. The results showed that feeding IgY before challenge had a small effect on the intestinal flora, and after challenge specific IgY decreased the proportion of Streptococcus and increased the diversity of the intestinal flora; in histopathology, specific IgY decreased tissue damage and maintained the integrity of tissue structure. Further study found that specific IgY can reduce intestinal epithelial cell apoptosis and reduce caspase activity; at the same time, the content of MDA was decreased, and the activities of SOD, CAT, GSH-Px and GR were increased. In addition, specific IgY can down-regulate the expression levels of IL-8 and TNF-α genes and up-regulate the expression levels of IL-10 and TGF-ß. The results of this study showed that specific IgY could improve the intestinal flora of tilapia infected with Streptococcus agalactiae, reduce intestinal cell apoptosis, oxidative stress injury and inflammatory response, thereby reducing tissue damage and protecting the health of tilapia. Overall, specific IgY can be further explored as a potential antibiotic alternative for gastrointestinal pathogen infections.
Asunto(s)
Alimentación Animal , Apoptosis , Pollos , Cíclidos , Enfermedades de los Peces , Microbioma Gastrointestinal , Inmunoglobulinas , Intestinos , Estrés Oxidativo , Infecciones Estreptocócicas , Streptococcus agalactiae , Animales , Streptococcus agalactiae/fisiología , Infecciones Estreptocócicas/veterinaria , Infecciones Estreptocócicas/inmunología , Estrés Oxidativo/efectos de los fármacos , Apoptosis/efectos de los fármacos , Inmunoglobulinas/inmunología , Cíclidos/inmunología , Pollos/inmunología , Enfermedades de los Peces/inmunología , Microbioma Gastrointestinal/efectos de los fármacos , Alimentación Animal/análisis , Intestinos/inmunología , Dieta/veterinaria , Yema de Huevo/inmunología , Yema de Huevo/químicaRESUMEN
Zinc is one of the essential microelements for the metabolism of animals. Zinc nanoparticles may have higher bioavailability due to their low specific surface area, facilitating absorption by fish. The present study aimed to evaluate the effects of supplementation with different zinc-based products on the growth and health of Nile tilapia Oreochromis niloticus. Zinc, in different sizes (nanoparticles or bulk) and forms (inorganic or organic), were used as a supplement in the tilapia diet at a dose of 15 mg kg feed-1 for 60 days. At the end of the feeding trial, production performance, hemato-immunological parameters, activity of antioxidant system enzymes, exposure to Streptococcus agalactiae and zinc concentration in the muscle were examined. After the bacterial challenge, the mean corpuscular hemoglobin concentration (MCHC) significantly increased in the fish treated with organic zinc, inorganic nano zinc, and organic nano zinc, while in the control group (inorganic zinc), MCHC remained unchanged. Regarding defense cells, dietary inorganic nano zinc increased the number of basophils (1.50 ± 1.10) compared to organic zinc (0.80 ± 0.90). Lymphocyte count increased after the challenge only in the organic zinc treatments (bulk and nanoparticles). Neutrophils decreased in the control (inorganic zinc) (2.20 ± 1.70) and inorganic nano zinc (2.60 ± 2.70) treatments after the challenge. When compared before and after the bacterial challenge, the plasma antimicrobial titer significantly increased after the bacterial challenge in all treatments. No significant differences were observed for total proteins, enzymes (SOD and CAT), cumulative survival and zinc deposition on fillet. In conclusion, organic zinc in nanoparticles or bulk size increased Nile tilapia innate defense during bacterial infection. However, the other parameters evaluated were not affected by zinc particle size or form (organic or inorganic), indicating that further evaluations should be conducted with organic zinc in nanoparticles or bulk size in the tilapia diet.
Asunto(s)
Alimentación Animal , Cíclidos , Dieta , Suplementos Dietéticos , Enfermedades de los Peces , Infecciones Estreptocócicas , Streptococcus agalactiae , Zinc , Animales , Cíclidos/inmunología , Cíclidos/crecimiento & desarrollo , Suplementos Dietéticos/análisis , Zinc/administración & dosificación , Alimentación Animal/análisis , Dieta/veterinaria , Infecciones Estreptocócicas/veterinaria , Infecciones Estreptocócicas/inmunología , Streptococcus agalactiae/fisiología , Enfermedades de los Peces/inmunología , Distribución Aleatoria , Inmunidad Innata/efectos de los fármacosRESUMEN
Group B Streptococcus (GBS; also known as Streptococcus agalactiae) is an opportunistic bacterial pathogen that causes sepsis, meningitis, pneumonia, and skin and soft tissue infections in neonates and healthy or immunocompromised adults. GBS is well-adapted to survive in humans due to a plethora of virulence mechanisms that afford responses to support bacterial survival in dynamic host environments. These mechanisms and responses include counteraction of cell death from exposure to excess metal ions that can cause mismetallation and cytotoxicity, and strategies to combat molecules such as reactive oxygen and nitrogen species that are generated as part of innate host defence. Cytotoxicity from reactive molecules can stem from damage to proteins, DNA, and membrane lipids, potentially leading to bacterial cell death inside phagocytic cells or within extracellular spaces within the host. Deciphering the ways in which GBS responds to the stress of cytotoxic reactive molecules within the host will benefit the development of novel therapeutic and preventative strategies to manage the burden of GBS disease. This review summarizes knowledge of GBS carriage in humans and the mechanisms used by the bacteria to circumvent killing by these important elements of host immune defence: oxidative stress, nitrosative stress, and stress from metal ion intoxication/mismetallation.
Asunto(s)
Metales , Infecciones Estreptocócicas , Streptococcus agalactiae , Streptococcus agalactiae/fisiología , Streptococcus agalactiae/patogenicidad , Humanos , Infecciones Estreptocócicas/microbiología , Infecciones Estreptocócicas/inmunología , Metales/metabolismo , Metales/toxicidad , Estrés Oxidativo , Especies Reactivas de Oxígeno/metabolismo , Estrés Fisiológico , Virulencia , Infecciones Oportunistas/microbiologíaRESUMEN
Fish rely on innate immune system for immunity, and nucleotide-binding oligomerization domain-like receptors (NLRs) are a vital group of receptor for recognition. In the present study, NOD1 gene was cloned and characterized from golden pompano Trachinotus ovatus, a commercially important aquaculture fish species. The ORF of T. ovatus NOD1 was 2820 bp long, encoding 939 amino acid residues with a highly conserved domains containing CARD-NACHT-LRRs. Phylogenetic analysis revealed that the T. ovatus NOD1 clustered with those of fish and separated from those of birds and mammals. T. ovatus NOD1 has wide tissue distribution with the highest expression in gills. Bacterial challenges (Streptococcus agalactiae and Vibrio alginolyticus) significantly up-regulated the expression of NOD1 with different response time. The results of T. ovatus NOD1 ligand recognition and signaling pathway analysis revealed that T. ovatus NOD1 could recognize iE-DAP at the concentration of ⧠100 ng/mL and able to activate NF-κB signaling pathway. This study confirmed that NOD1 play a crucial role in the innate immunity of T. ovatus. The findings of this study improve our understanding on the immune function of NOD1 in teleost, especially T. ovatus.
Asunto(s)
Secuencia de Aminoácidos , Enfermedades de los Peces , Proteínas de Peces , Inmunidad Innata , Proteína Adaptadora de Señalización NOD1 , Filogenia , Alineación de Secuencia , Vibrio alginolyticus , Animales , Proteína Adaptadora de Señalización NOD1/genética , Proteína Adaptadora de Señalización NOD1/inmunología , Proteína Adaptadora de Señalización NOD1/química , Proteínas de Peces/genética , Proteínas de Peces/inmunología , Proteínas de Peces/química , Inmunidad Innata/genética , Enfermedades de los Peces/inmunología , Alineación de Secuencia/veterinaria , Vibrio alginolyticus/fisiología , Infecciones Estreptocócicas/inmunología , Infecciones Estreptocócicas/veterinaria , Streptococcus agalactiae/fisiología , Regulación de la Expresión Génica/inmunología , Perfilación de la Expresión Génica/veterinaria , Vibriosis/inmunología , Vibriosis/veterinaria , Ácido Diaminopimélico/química , Ácido Diaminopimélico/análogos & derivados , Perciformes/inmunología , Perciformes/genética , Peces/inmunología , Peces/genéticaRESUMEN
Using the unique structures found in natural materials to produce new antibacterial drugs is crucial. Actinobacteria is well-known for its ability to produce naturally occurring chemicals with a variety of structural features that can be used as weapons against infectious bacteria. In the present study, the Streptomyces coeruleorubidus metabolites were characterized and their efficacy in suppressing Streptococcus agalactiae growth was carried out both in vitro and in vivo. The metabolites of S. coeruleorubidus were purified and identified as octasiloxane-hexadecamethyl (OHM). In vivo antibacterial activity of OHM revealed an inhibitory minimum concentration value of 0.5 µg/ml against S. agalactiae and induced ultrastructural cell changes revealed by scanning electron microscope. The safe concentration of OHM was determined as 0.8 mg/L for Nile tilapia. Four in vivo treatments were treated with 0 and 0.8 mg/L OHM and with or without challenge by S. agalactiae (1 × 107 CFU/mL) named control, OHM, S. agalactiae, and S. agalactiae + OHM groups. The OHM treatment improved the survival of Nile tilapia by 33.33% than S. agalactiae challenge group. Waterborne OHM treatment significantly mitigated the deleterious effects of S. agalactiae on hematological, hepato-renal functions, stress indicators, and antioxidant balance. OHM significantly alleviated nitric oxide levels, complement 3, IgM, and lysozyme activity, downregulation of liver antioxidant genes expression in S. agalactiae group. Furthermore, the addition of OHM to challenged fish with S. agalactiae-significantly reversed dramatic negative regulation of inflammatory, apoptosis, and immune related gene expression (caspase-3, bax, pcna, tnf-α, ifn-γ, il-8 il-1ß, il-10, tgf-ß, and bcl-2 in the Nile tilapia spleen. Additionally, the damaged hepatic and splenic structure induced by bacterial infection was restored with OHM treatment. Finally, S. coeruleorubidus metabolites (mainly OHM) revealed in vitro and in vivo antibacterial activity and showed alleviated effects on the physiological status of S. agalactiae infected tilapia.
Asunto(s)
Cíclidos , Enfermedades de los Peces , Infecciones Estreptocócicas , Streptomyces , Animales , Citocinas/genética , Streptococcus agalactiae/fisiología , Antioxidantes , Antibacterianos/farmacología , Estrés Oxidativo , Expresión Génica , ApoptosisRESUMEN
As a lymphocyte-specific surface receptor belonging to the cysteine-rich superfamily of scavenger receptors, CD6 acts as a pattern recognition receptor for microbial components and is involved in the regulation of inflammatory responses. However, the characteristics and functions of CD6 molecules in lower vertebrates represented by teleost fish are unknown. In this study, a CD6 homolog (designated OnCD6) was characterized from Nile tilapia (Oreochromis niloticus), and establishing its role as a PRRs that participates in immune recognition. OnCD6 contains an open reading frame of 1872 bp that encodes a peptide of 623 amino acids, and contains two conserved SR domain. Multiple sequence alignment revealed that OnCD6 shares a relatively high level of identity with those of other species. Transcriptional expression analysis revealed that OnCD6 was constitutively expressed in immunes tissues such as head kidney and thymus. The expression level of OnCD6 in mainly immune tissues were found significantly upregulated after the injection of Streptococcus agalactiae (S. agalactiae). Moreover, OnCD6 protein was located in the head kidney and brain, mainly over the plasma membrane of lymphocytes in these immune tissues. In vitro experiments showed that CD6 extracellular protein bound to and aggregated several Gram-positive and -negative bacterial strains through the recognition of bacterial surface conserved components LPS and LTA etc. In vivo experiments demonstrated that overexpression OnCD6 before S. agalactiae challenge significantly improved tilapia survival, and this was concomitant with reduced bacterial load and pro-inflammatory cytokines (IL-1ß and TNF-α). Taken together, our results illustrated the function of CD6 molecular pattern recognition receptors (PRRs) is conserved and plays an important role in antibacterial infection.
Asunto(s)
Cíclidos , Enfermedades de los Peces , Infecciones Estreptocócicas , Animales , Streptococcus agalactiae/fisiología , Secuencia de Aminoácidos , Citocinas/metabolismo , Inflamación , Proteínas de Peces/química , Infecciones Estreptocócicas/veterinaria , Regulación de la Expresión GénicaRESUMEN
Nile tilapia (Oreochromis niloticus) occupies an important position in the culture of economic fish in China. However, the high mortality caused by streptococcal disease has had a significant impact on the tilapia farming industry. Therefore, it is necessary to clarify the immune mechanism of tilapia in response to Streptococcus agalactiae. As a hub in the natural immune signaling pathway, the junction molecule can help the organism defend against and clear pathogens and is crucial in the signaling pathway. In this study, the cDNA sequence of Nile tilapia TBK1 was cloned, and the expression profile was examined in normal fish and challenged fish. The cDNA sequence of the TBK1 gene was 3378 bp, and its open reading frame (ORF) was 2172 bp, encoding 723 amino acids. The deduced TBK1 protein contained an S_TKc domain, a coiled coil domain and a ubiquitin-like domain (ULD). TBK1 had the highest homology with zebra mbuna (Maylandia zebra) and Lake Malawi cichlid fish (Astatotilapia calliptera), both at 97.59%. In the phylogenetic tree, TBK1 forms a large branch with other scleractinian fish. TBK1 expression was highest in the brain and lowest in the liver. LPS, Poly I:C, and S. agalactiae challenge resulted in significant changes in TBK1 expression in the tissues examined. The subcellular localization showed that TBK1-GFP was distributed in the cytoplasm and could significantly increase IFN-ß activation. Pull-down results showed that there was an interaction between TBK1 and TRAF3 and an interaction between STING protein and TBK1 protein. The above results provide a basis for further investigation into the mechanism of TBK1 involvement in the signaling pathway.
Asunto(s)
Cíclidos , Enfermedades de los Peces , Infecciones Estreptocócicas , Animales , Factor 3 Asociado a Receptor de TNF/genética , Secuencia de Aminoácidos , Filogenia , ADN Complementario , Inmunidad , Streptococcus agalactiae/fisiología , Proteínas de Peces/química , Regulación de la Expresión GénicaRESUMEN
Tilapia is one of the most economically important freshwater fish farmed in China. Streptococcosis outbreaks have been extensively documented in farmed tilapia species. Hybrid tilapia (Oreochromis niloticus â × O. aureus â) exhibit greater disease resistance than Nile tilapia (O. niloticus) and blue tilapia (O. aureus). However, the molecular mechanism underlying the enhanced tolerance of hybrid tilapia is still poorly understood. In this study, comparative transcriptome analysis was performed to reveal the different tolerance mechanisms to Streptococcus agalactiae in the three tilapia lines. In total, 1982, 2355, and 2076 differentially expressed genes were identified at 48 h post-infection in hybrid tilapia, Nile tilapia, and blue tilapia, respectively. Functional enrichment analysis indicated that numerous metabolic and immune-related pathways were activated in all three tilapia lines. The differential expression of specific genes associated with phagosome, focal adhesion, cytokine-cytokine receptor interaction, and toll-like receptor signaling pathways contributed to the resistance of hybrid tilapia. Notably, immune response genes in hybrid tilapia, such as P38, TLR5, CXCR3, CXCL12, PSTPIP1, and TFR, were generally suppressed under normal conditions but selectively induced following pathogen challenge. These results expand our knowledge of the molecular mechanisms underlying S. agalactiae tolerance in hybrid tilapia and provide valuable insights for tilapia breeding programs.
Asunto(s)
Cíclidos , Enfermedades de los Peces , Infecciones Estreptocócicas , Tilapia , Animales , Tilapia/genética , Cíclidos/genética , Transcriptoma , Streptococcus agalactiae/fisiología , Perfilación de la Expresión Génica/veterinariaRESUMEN
The antibacterial activity of aqueous (AE) or ethanolic extracts (EE) of caper (Capparis spinosa) against Streptococcus agalactiae was evaluated in vitro. Both caper extracts showed antagonistic activity against S. agalactiae and the inhibition zones in case of ethanolic extracts were larger than those of aqueous ones. Additionally, TEM investigations show that S. agalactiae cells treated with both C. spinosa extracts were damaged and degraded and this damage was greater in case of ethanolic extract. Another study was done to assess the promotion effects of dietary caper (C. spinosa) extracts on growth, antioxidant and immune activity, and inflammation cytokine responses of Nile tilapia (Oreochromis niloticus) and its resistance to S. agalactiae infection. However, fish (40 ± 2 g) were fed on diets containing 1.0 and 2.0 g/kg feed of each caper extract as well as the control group (free of caper) for 6 weeks. Fish were intraperitoneally injected (IP) with Streptococcus agalactiae at the end of the feeding trial, and fish mortality was tracked for additional ten days. Compared with other treatments, fish fed on 2.0 g EE/kg feed had higher counts of white and red blood cells as well as higher hemoglobin levels accompanied with lower AST and ALT activities. Antioxidant (superoxide dismutase and catalase activities) and immune, total protein, globulin, lysozyme, and immunoglobulin M) indices were increased along with significant decline in MDA levels in both caper extracts treated fish groups compared to the control group. Significant promotion in fish growth was affected positively with the increase in both caper extracts; particularly, the larger fish growth was observed in the treatment of 2.0 g EE/kg feed. Expressions of IL-1ß and IL-8 were declined; meanwhile levels of IL-10, SOD and CAT genes were upregulated in fish fed on 2.0 g EE/kg feed compared to other groups. After being challenged with S. agalactiae infection, fish survival was considerably (P < 0.05) greater in fish groups that fed on diets with caper extracts; particularly 2.0 g EE/kg feed (75%); while all fish fed on the control one were dead. According to these findings, the antioxidant and immune response of Nile tilapia fingerlings is stimulated by ethanolic extract of caper (2.0 g/kg feed), which also enhanced the growth performance and fish resistance to S. agalactiae infection.
Asunto(s)
Capparis , Cíclidos , Enfermedades de los Peces , Animales , Antioxidantes , Suplementos Dietéticos , Streptococcus agalactiae/fisiología , Citocinas , Dieta/veterinaria , Inflamación , Alimentación Animal/análisis , Resistencia a la EnfermedadRESUMEN
Apolipoprotein E (ApoE), a critical targeting protein, has been found to play an essential role in the protection against infection and inflammation. However, the immune functions of ApoE against bacterial infection in fish have not been investigated. In this study, a full-length cDNA for ApoE, named On-ApoEb was cloned from Oreochromis niloticus. The predicted cDNA sequence was 831bp in length and coded for a protein of 276 amino acid residues, which shared 63.87%-98.55% identity with ApoEb from other fishes, and about 22% identity with ApoEb from mammals. On-ApoEb from O. niloticus was highly expressed in the liver and could be activated in the tissues (liver, spleen, brain, and intestine) after infection with Streptococcus agalactiae. Moreover, the results revealed that On-ApoEb could decrease the expression levels of pro-inflammatory factors, immune-related pathways, and apoptosis, while increasing the expression levels of anti-inflammatory factors. Furthermore, On-ApoEb was noted to improve the survival rate and reduce the bacterial load in the liver and spleen. These results suggested that On-ApoEb was connected with immune response and had anti-inflammation and anti-apoptosis activities.
Asunto(s)
Cíclidos , Enfermedades de los Peces , Infecciones Estreptocócicas , Animales , Secuencia de Aminoácidos , Streptococcus agalactiae/fisiología , ADN Complementario/genética , Apolipoproteínas/genética , Apolipoproteínas E/genética , Apolipoproteínas E/metabolismo , Proteínas de Peces/química , Regulación de la Expresión Génica , Mamíferos/metabolismoRESUMEN
Interleukin 8 (IL8) is vital in promoting inflammation and is a crucial mediator in various physiopathological processes while influencing immunological function. The effect of IL8 on the immunological response to acute bacterial infections in Nile tilapia (Oreochromis niloticus) remains unknown. This work found an IL8 gene from Nile tilapia (On-IL8). It includes a 285 bp open reading frame and codes for 94 amino acids. The transcript levels of On-IL8 were highest in the head-kidney tissue and sharply induced by Streptococcus agalactiae and Aeromonas hydrophila. Besides, in vitro experiments revealed that On-IL8 regulated a variety of immunological processes and promoted inflammatory responses. Moreover, On-IL8 suppressed the NF-κB signaling pathway, consistent with in vitro results. These significant findings serve as the basis for further investigation into how IL8 confers protection to bony fish in opposition to bacterial infections.
Asunto(s)
Cíclidos , Enfermedades de los Peces , Infecciones Estreptocócicas , Animales , Interleucina-8/genética , Infecciones Estreptocócicas/veterinaria , Regulación de la Expresión Génica , Secuencia de Aminoácidos , Proteínas de Peces/química , Streptococcus agalactiae/fisiologíaRESUMEN
CD27 is a member of the TNF-receptor superfamily and plays various roles in immunities. However, the detailed information and mechanism of CD27 in bony fish immunity remain unclear. Therefore, in this research, certain interesting roles of CD27 in Nile tilapia (On-CD27) were determined. On-CD27 was largely expressed in the immune organs, head kidney, and spleen, and was sharply induced during bacterial infection. The in vitro tests suggested On-CD27 was involved in regulating inflammatory responses, activating immune-related signal pathways, and inducing apoptosis and pyroptosis progress. The scRNA data and in vivo experiments indicated that On-CD27 is mainly expressed in CD4+ T cells and involved in both innate and adaptive immunities. The present data provide a theoretical principle for further research on the mechanisms of CD27 in the innate and adaptive immunities of fish.
Asunto(s)
Cíclidos , Enfermedades de los Peces , Infecciones Estreptocócicas , Animales , Proteínas de Peces , Bazo , Riñón Cefálico , Streptococcus agalactiae/fisiología , Inmunidad Innata/genética , Regulación de la Expresión GénicaRESUMEN
Apolipoprotein A-I (ApoA-I) is a lipoprotein involved in a variety of physiological and pathological processes. However, the immunomodulatory functions of ApoA-I in fish are not well understood. In this study, ApoA-I from Nile tilapia (Oreochromis niloticus) (On-ApoA-I) was identified, and its function in bacterial infection was investigated. The open reading frame of On-ApoA-I is 792 bp, which codes for a protein containing 263 amino acids. On-ApoA-I shared over 60% sequence similarity with other teleost fish and more than 20% with mammalian ApoA-I. On-ApoA-I was found to be highly expressed in the liver and significantly induced during Streptococcus agalactiae infection by qRTâPCR analysis. Furthermore, invivo studies revealed that recombinant On-ApoA-I protein could suppress inflammation and apoptosis and improve the likelihood of surviving bacterial infection. Additionally, On-ApoA-I showed invitro antimicrobial properties against Gram-positive and Gram-negative bacteria. These findings offer a theoretical basis for further investigations into the role of ApoA-I in fish immunology.
Asunto(s)
Cíclidos , Enfermedades de los Peces , Infecciones Estreptocócicas , Animales , Apolipoproteína A-I/genética , Apolipoproteína A-I/metabolismo , Antibacterianos , Bacterias Gramnegativas , Bacterias Grampositivas , Infecciones Estreptocócicas/veterinaria , Streptococcus agalactiae/fisiología , Proteínas de Peces/química , Regulación de la Expresión Génica , Mamíferos/metabolismoRESUMEN
Nile tilapia (Oreochromis niloticus) is one of the major food fish worldwide. The farming business, on the other hand, has faced considerable obstacles, such as disease infestations. Toll-like receptors (TLRs) play an important function in the activation of the innate immune system in response to infections. Unc-93 homolog B1 (UNC93B1) is a key regulator of nucleic acid (NA)-sensing TLRs. Here the UNC93B1 gene, which was cloned from Nile tilapia tissue for this investigation, had the same genetic structure as a homologous gene in humans and mice. Phylogenetic analysis revealed that Nile tilapia UNC93B1 clustered with UNC93B1 from other species and separately from the UNC93A clade. The gene structure of the Nile tilapia UNC93B1 was found to be identical to that of human UNC93B1. Our gene expression studies revealed that Nile tilapia UNC93B1 was highly expressed in the spleen, followed by other immune-related tissues such as the head kidney, gills, and intestine. Moreover, Nile tilapia UNC93B1 mRNA transcripts were up-regulated in vivo in the head kidney and spleen tissues from poly I:C and Streptococcus agalactiae injected Nile tilapia, as well as in vitro in LPS stimulated Tilapia head kidney (THK) cells. The Nile tilapia UNC93B1-GFP protein signal was detected in the cytosol of THK cells and was co-localized with endoplasmic reticulum and lysosome but not with mitochondria. Moreover, the results of a co-immunoprecipitation and immunostaining analysis showed that Nile tilapia UNC93B1 can be pulled down with fish-specific TLRs such as TLR18 and TLR25 from Nile tilapia, and was found to be co-localized with these fish-specific TLRs in the THK cells. Overall, our findings highlight the potential role of UNC93B1 as an accessory protein in fish-specific TLR signaling.