Fishing for lymphoid genes

Zebrafish (Danio rerio) as a Model System to Investigate the Role of the Innate Immune Response in Human Infectious Diseases

The zebrafish (Danio rerio) has emerged as a valuable model for studying host-pathogen interactions due to its unique combination of characteristics. These include extensive sequence and functional conservation with the human genome, optical transparency in larvae that allows for high-resolution visualization of host cell-microbe interactions, a fully sequenced and annotated genome, advanced forward and reverse genetic tools, and suitability for chemical screening studies. Despite anatomical differences with humans, the zebrafish model has proven instrumental in investigating immune responses and human infectious diseases. Notably, zebrafish larvae rely exclusively on innate immune responses during the early stages of development, as the adaptive immune system becomes fully functional only after 4-6 weeks post-fertilization. This window provides a unique opportunity to isolate and examine infection and inflammation mechanisms driven by the innate immune response without the confounding effects of adaptive immunity. In this review, we highlight the strengths and limitations of using zebrafish as a powerful vertebrate model to study innate immune responses in infectious diseases. We will particularly focus on host-pathogen interactions in human infections caused by various bacteria (Clostridioides difficile, Staphylococcus aureus, and Pseudomonas aeruginosa), viruses (herpes simplex virus 1, SARS-CoV-2), and fungi (Aspergillus fumigatus and Candida albicans).

Cuban Policosanol (Raydel®) Exerts Higher Antioxidant and Anti-Glycation Activities than Chinese Policosanol (BOC Sciences) in Reconstituted High-Density Lipoproteins: In Vivo Anti-Inflammatory Activities in Zebrafish and Its Embryos

The present study compares sugarcane-wax purified policosanols sourced from Cuba (Raydel®) and China (BOC Sciences) and utilized following the synthesis of reconstituted high-density lipoproteins (rHDL). The two policosanols exhibited distinctly different ingredient ratios of long-chain aliphatic alcohols, particularly 1-octacosanol (C28) and 1-tetratriacotanol (C34). After synthesizing rHDL with apolipoprotein A-I (apoA-I), the two policosanols bound well with phospholipid and apoA-I to form the discoidal rHDL. Notably, rHDL-1, containing Cuban policosanol, displayed the largest particle diameter at approximately 78 ± 3 nm. In contrast, both control rHDL (rHDL-0) and rHDL containing Chinese policosanol (rHDL-2) exhibited smaller particles, with diameters of approximately 58 ± 3 nm and 61 ± 2 nm, respectively. Furthermore, rHDL-1 demonstrated enhanced anti-glycation activity, safeguarding apoA-I from degradation within HDL, and displayed the antioxidant ability to inhibit LDL oxidation. A microinjection of each rHDL into zebrafish embryos in the presence of carboxymethyllysine (CML) revealed rHDL-1 to have the strongest antioxidant activity with the highest embryo survivability and normal developmental morphology. Dermal application to recover the wound revealed rHDL-1 to have the highest wound-healing activity (75%) and survivability (92%) in the cutaneous wound area in the presence of CML. In adult zebrafish, injecting CML (250 μg) caused acute death and hyperinflammation, marked by heightened neutrophil infiltration and interleukin (IL)-6 production in liver. However, co-administering rHDL-1 notably increased survival (85%) and exhibited strong anti-inflammatory properties, reducing IL-6 production while improving the blood lipid profile. However, a co-injection of rHDL-2 resulted in the lowest survivability (47%) with more hepatic inflammation. In conclusion, Cuban policosanol (Raydel®) has more desirable properties for the in vitro synthesis of rHDL with stronger anti-glycation and antioxidant activities than those of Chinese policosanol (BOC Sciences). Moreover, Raydel-policosanol-integrated rHDL demonstrates a noteworthy effect on accelerated wound healing and robust anti-inflammatory properties, leading to increased survivability in zebrafish embryos and adults by effectively suppressing CML-induced hyperinflammation.

Synergistic Anti-Inflammatory Activity of Apolipoprotein A-I and CIGB-258 in Reconstituted High-Density Lipoproteins (rHDL) against Acute Toxicity of Carboxymethyllysine in Zebrafish and Its Embryo

CIGB-258 is a 3 kDa altered peptide ligand from heat shock protein (HSP) 60 that exhibits anti-inflammatory activity against the acute toxicity of carboxymethyllysine (CML) with antioxidant and anti-glycation activities via protection of high-density lipoprotein (HDL) and apolipoprotein A-I (apoA-I). It is necessary to test a synergistic interaction between apoA-I and CIGB-258 in reconstituted high-density lipoproteins (rHDL). Several rHDLs were synthesized containing palmitoyloleoyl phosphatidylcholine (POPC), cholesterol, apoA-I, and CIGB-258 at molar ratios of 95:5:1:0, 95:5:1:0.1, 95:5:1:0.5, and 95:5:1:1 for rHDL-(1:0), rHDL-(1:0.1), rHDL-(1:0.5), and rHDL-(1:1), respectively. As the CIGB-258 content in rHDL was increased, the particle size of rHDL was 1.4-times higher than rHDL-(1:0) to rHDL-(1:1), from 60 nm to 83 nm, respectively. As the CIGB-258 content was increased, the rHDL showed the most resistance to isothermal denaturation by a urea treatment, and rHDL-(1:1) exhibited the highest structural stability and the strongest antioxidant ability against LDL oxidation. Co-treatment of rHDL-(1:0), rHDL-(1:0.5), and rHDL-(1:1) resulted in up to 10%, 24%, and 34% inhibition of HDL glycation, inhibition of HDL glycation, which was caused by the CML, with protection of apoA-I. Microinjection of each rHDL into zebrafish embryos in the presence of CML showed that a higher CIGB-258 content in rHDL was associated with higher survivability with the least inflammation and apoptosis. Furthermore, an intraperitoneal injection of rHDL and CML showed that a higher CIGB-258 content in rHDL was also associated with higher survivability of zebrafish and faster recovery of swimming ability. The rHDL-(1:1) group showed the lowest triglyceride, AST, and ALT serum levels with the least production of interleukin-6, oxidized product, and neutrophil infiltration in hepatic tissue. In conclusion, CIGB-258 could bind well to phospholipids and cholesterol to stabilize apoA-I in the rHDL structure against denaturation stress and larger particle sizes. The rHDL containing CIGB-258 enhanced the in vitro antioxidant ability against LDL oxidation, the anti-glycation activity to protect HDL, and the in vivo anti-inflammatory activity against CML toxicity in zebrafish adults and embryos. Overall, incorporating apoA-I and CIGB-258 in rHDL resulted in a synergistic interaction to enhance the structural and functional correlations in a dose-dependent manner of CIGB-258.

Combination Therapy of Cuban Policosanol (Raydel®, 20 mg) and Intensive Exercise for 12 Weeks Resulted in Improvements in Obesity, Hypertension, and Dyslipidemia without a Decrease in Serum Coenzyme Q10: Enhancement of Lipoproteins Quality and Antioxidant Functionality in Obese Participants

Obesity and overweight, frequently caused by a lack of exercise, are associated with many metabolic diseases, such as hypertension, diabetes, and dyslipidemia. Aerobic exercise effectively increases the high-density lipoproteins-cholesterol (HDL-C) levels and alleviates the triglyceride (TG) levels. The consumption of Cuban policosanol (Raydel®) is also effective in enhancing the HDL-C quantity and HDL functionality to treat dyslipidemia and hypertension. On the other hand, no study has examined the effects of a combination of high-intensity exercise and policosanol consumption in obese subjects to improve metabolic disorders. In the current study, 17 obese subjects (average BMI 30.1 ± 1.1 kg/m2, eight male and nine female) were recruited to participate in a program combining exercise and policosanol (20 mg) consumption for 12 weeks. After completion, their BMI, waist circumference, total fat mass, systolic blood pressure (SBP), and diastolic blood pressure (DBP) reduced significantly up to around -15%, -13%, -33%, -11%, and -13%, respectively. In the serum lipid profile, at Week 12, a significant reduction was observed in the total cholesterol (TC) and triglyceride (TG) levels, up to -17% and -54% from the baseline, respectively. The serum HDL-C was elevated by approximately +12% from the baseline, as well as the percentage of HDL-C in TC, and HDL-C/TC (%), was enhanced by up to +32% at Week 12. The serum coenzyme Q10 (CoQ10) level was increased 1.2-fold from the baseline in all participants at Week 12. In particular, the male participants exhibited a 1.4-fold increase from the baseline. The larger rise in serum CoQ10 was correlated with the larger increase in the serum HDL-C (r = 0.621, p = 0.018). The hepatic function parameters were improved; the serum γ-glutamyl transferase decreased at Week 12 by up to -55% (p < 0.007), while the aspartate aminotransferase and alanine transaminase levels diminished within the normal range. In the lipoprotein level, the extent of oxidation and glycation were reduced significantly with the reduction in TG content. The antioxidant abilities of HDL, such as paraoxonase (PON) and ferric ion reduction ability (FRA), were enhanced significantly by up to 1.8-fold and 1.6-fold at Week 12. The particle size and number of HDL were elevated up to +10% during the 12 weeks, with a remarkable decline in the TG content, glycation extent, and oxidation. The improvements in HDL quality and functionality were linked to the higher survivability of adult zebrafish and their embryos, under the co-presence of carboxymethyllysine (CML), a pro-inflammatory molecule known to cause acute death. In conclusion, 12 weeks of Cuban policosanol (Raydel®, 20 mg) consumption with high-intensity exercise displayed a significant improvement in blood pressure, body fat mass, blood lipid profile without liver damage, CoQ10 metabolism, and renal impairment.

Enhancement of Antioxidant and Anti-Glycation Properties of Beeswax Alcohol in Reconstituted High-Density Lipoprotein: Safeguarding against Carboxymethyllysine Toxicity in Zebrafish

The antioxidant and anti-inflammatory abilities of beeswax alcohol (BWA) are well reported in animal and human clinical studies, with a significant decrease in malondialdehyde (MDA) in the blood, reduced liver steatosis, and decreased insulin. However, there has been insufficient information to explain BWAs in vitro antioxidant and anti-inflammatory activity owing to its limited solubility in an aqueous buffer system. Herein, three distinct reconstituted high-density lipoproteins (rHDL) were prepared with palmitoyloleoyl phosphatidylcholine (POPC), cholesterol, apolipoprotein A-I (apoA-I), and BWA at molar ratios of 95:5:1:0 (rHDL-0), 95:5:1:0.5 (rHDL-0.5), and 95:5:1:1 (rHDL-1) and examined for antioxidant and anti-glycation effects. A rHDL containing BWA, precisely rHDL-1, displayed a remarkable anti-glycation effect against fructose (final 250 mM), induced glycation of HDL, and prevented proteolytic degradation of apoA-I. Also, BWA incorporated rHDL-0.5, and rHDL-1 displayed substantial antioxidant activity by inhibiting cupric ion-mediated low-density lipoprotein (LDL) oxidation. In contrast to rHDL-0, a 20 and 22% enhancement in ferric ion reduction ability (FRA) and paraoxonase (PON) activity was observed in HDL treated with rHDL-1, signifying the effect of BWA on the antioxidant activity enhancement of HDL. rHDL-1 efficiently inhibits Nε-carboxylmethyllysine (CML)-induced reactive oxygen species (ROS) generation and apoptosis in zebrafish embryos, consequently improving embryo survivability and developmental deformities impaired by the CML. The dermal application of rHDL-1 to the CML-impaired cutaneous wound of the adult zebrafish inhibited ROS production and displayed potent wound-healing activity. Conclusively, incorporating BWA in rHDL significantly enhanced the anti-glycation and antioxidant activities in rHDL via more stabilization of apoA-I with a larger particle size. The rHDL containing BWA facilitated the inherent antioxidant ability of HDL to suppress the CML-induced toxicities in zebrafish embryos and ameliorate CML-aggravated chronic wounds in adult zebrafish.

Development of the Thymus and Kidney and Effects of Resveratrol on Their Aging in a Short-Lived Fish

Annual fishes of the genus Nothobranchius have been widely used in cognitive, behavioral, and genetic studies, and have become an excellent animal model for studying aging. However, the development and degeneration of immune organs in annual fishes and the antagonistic effects of resveratrol remain unclear. In the present study, the development of thymus and kidney was investigated systematically using Nothobranchius guentheri from larvae, juveniles, and young and old fish with hematoxylin and eosin staining. We found that thymus primordium was observed first in the larvae at 2 days after hatching (dah). After the lymphoid cells became evident at 5 dah, the thymus acquired an irregular shape at 7 dah. Then it formed a wedge shape at 15 dah. Thymus looked as homogeneous distribution of lymphocytes at 1 month old, and it differentiated into cortex and medulla approximately in 2-month-old fish. Combined with TUNEL and senescence-associated β-galactosidase (SA-β-gal) staining, it showed the degeneration of the thymus appeared in 4-month-old fish. Kidney primordium appeared on 1 dah, and the glomerulus was visible at 7 dah. The nephrogenic activity was most apparent in 1-month-old fish. A large hematopoietic tissue was arranged in the renal interstitium in 2- and 3-month-old fish. In 6-month-old fish, the kidney structure became less dense. By 12 months, the kidney exhibited the most pronounced histological characteristics of aging. Feeding resveratrol ameliorated renal fibrosis and SA-β-gal staining with age, increased SIRT1 and SIRT3 expression, and decreased the levels of NF-κB and inflammatory factors in thymus and kidney of the fish. We provided basic data for the development and degeneration of immune organs and resveratrol's anti-aging effects in short-lived fish.

Beneficial Effect of Cuban Policosanol on Blood Pressure and Serum Lipoproteins Accompanied with Lowered Glycated Hemoglobin and Enhanced High-Density Lipoprotein Functionalities in a Randomized, Placebo-Controlled, and Double-Blinded Trial with Healthy Japanese

This study evaluated the efficacy and safety of 20 mg of Cuban policosanol in blood pressure (BP) and lipid/lipoprotein parameters of healthy Japanese subjects via a placebo-controlled, randomized, and double-blinded human trial. After 12 weeks of consumption, the policosanol group showed significantly lower BP, glycated hemoglobin (HbA1c), and blood urea nitrogen (BUN) levels. The policosanol group also showed lower aspartate aminotransferase (AST), alanine aminotransferase (ALT), and γ-glutamyl transferase (γ-GTP) levels at week 12 than those at week 0: A decrease of up to 9% (p < 0.05), 17% (p < 0.05), and 15% (p < 0.05) was observed, respectively. The policosanol group showed significantly higher HDL-C level and HDL-C/TC (%), approximately 9.5% (p < 0.001) and 7.2% (p = 0.003), respectively, than the placebo group and a difference in the point of time and group interaction (p < 0.001). In lipoprotein analysis, the policosanol group showed a decrease in oxidation and glycation extent in VLDL and LDL with an improvement of particle shape and morphology after 12 weeks. HDL from the policosanol group showed in vitro stronger antioxidant and in vivo anti-inflammatory abilities. In conclusion, 12 weeks of Cuban policosanolconsumption in Japanese subjects showed significant improvement in blood pressure, lipid profiles, hepatic functions, and HbA1c with enhancement of HDL functionalities.

Cuban Sugar Cane Wax Alcohol Exhibited Enhanced Antioxidant, Anti-Glycation and Anti-Inflammatory Activity in Reconstituted High-Density Lipoprotein (rHDL) with Improved Structural and Functional Correlations: Comparison of Various Policosanols

Policosanols from various sources, such as sugar cane, rice bran, and insects, have been marketed to prevent dyslipidemia, diabetes, and hypertension by increasing the blood high-density lipoproteins cholesterol (HDL-C) levels. On the other hand, there has been no study on how each policosanol influences the quality of HDL particles and their functionality. Reconstituted high-density lipoproteins (rHDLs) with apolipoprotein (apo) A-I and each policosanol were synthesized using the sodium cholate dialysis method to compare the policosanols in lipoprotein metabolism. Each rHDL was compared regarding the particle size and shape, antioxidant activity, and anti-inflammatory activity in vitro and in zebrafish embryos. This study compared four policosanols including one policosanol from Cuba (Raydel^® policosanol) and three policosanols from China (Xi'an Natural sugar cane, Xi'an Realin sugar cane, and Shaanxi rice bran). The synthesis of rHDLs with various policosanols (PCO) from Cuba or China using a molar ratio of 95:5:1:1 with palmitoyloleoyl phosphatidylcholine (POPC): free cholesterol (FC): apoA-I:PCO (wt:wt) showed that rHDL containing Cuban policosanol (rHDL-1) showed the largest particle size and the most distinct particle shape. The rHDL-1 showed a 23% larger particle diameter and increased apoA-I molecular weight with a 1.9 nm blue shift of the maximum wavelength fluorescence than rHDL alone (rHDL-0). Other rHDLs containing Chinese policosanols (rHDL-2, rHDL-3, and rHDL-4) showed similar particle sizes with an rHDL-0 and 1.1-1.3 nm blue shift of wavelength maximum fluorescence (WMF). Among all rHDLs, the rHDL-1 showed the strongest antioxidant ability to inhibit cupric ion-mediated LDL oxidation. The rHDL-1-treated LDL showed the most distinct band intensity and particle morphology compared with the other rHDLs. The rHDL-1 also exerted the highest anti-glycation activity to inhibit the fructose-mediated glycation of human HDL₂ with the protection of apoA-I from proteolytic degradation. At the same time, other rHDLs showed a loss of anti-glycation activity with severe degradation. A microinjection of each rHDL alone showed that rHDL-1 had the highest survivability of approximately 85 ± 3%, with the fastest developmental speed and morphology. In contrast, rHDL-3 showed the lowest survivability, around 71 ± 5%, with the slowest developmental speed. A microinjection of carboxymethyllysine (CML), a pro-inflammatory advanced glycated end product, into zebrafish embryos resulted in severe embryo death of approximately 30 ± 3% and developmental defects with the slowest developmental speed. On the other hand, the phosphate buffered saline (PBS)-injected embryo showed 83 ± 3% survivability. A co-injection of CML and each rHDL into adult zebrafish showed that rHDL-1 (Cuban policosanol) induced the highest survivability, around 85 ± 3%, while rHDL-0 showed 67 ± 7% survivability. In addition, rHDL-2, rHDL-3, and rHDL-4 showed 67 ± 5%, 62 ± 37, and 71 ± 6% survivability, respectively, with a slower developmental speed and morphology. In conclusion, Cuban policosanol showed the strongest ability to form rHDLs with the most distinct morphology and the largest size. The rHDL-containing Cuban policosanol (rHDL-1) showed the strongest antioxidant ability against LDL oxidation, anti-glycation activity to protect apoA-I from degradation, and the highest anti-inflammatory activity to protect embryo death under the presence of CML.

Marine fungal metabolite butyrolactone I prevents cognitive deficits by relieving inflammation and intestinal microbiota imbalance on aluminum trichloride-injured zebrafish

Background

Mounting evidences indicate that oxidative stress, neuroinflammation, and dysregulation of gut microbiota are related to neurodegenerative disorders (NDs). Butyrolactone I (BTL-I), a marine fungal metabolite, was previously reported as an in vitro neuroprotectant and inflammation inhibitor. However, little is known regarding its in vivo effects, whereas zebrafish (Danio rerio) could be used as a convenient in vivo model of toxicology and central nervous system (CNS) diseases.

Methods

Here, we employed in vivo and in silico methods to investigate the anti-NDs potential of BTL-I. Specifically, we established a cognitive deficit model in zebrafish by intraperitoneal (i.p.) injection of aluminum trichloride (AlCl₃) (21 μg) and assessed their behaviors in the T-maze test. The proinflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) as well as acetylcholinesterase (AChE) activity or glutathione (GSH) levels were assayed 24 h after AlCl₃ injection. The intestinal flora variation of the zebrafish was investigated by 16S rDNA high-throughput analysis. The marine fungal metabolite, butyrolactone I (BTL-I), was used to modulate zebrafish cognitive deficits evoked by AlCl₃ and evaluated about its effects on the above inflammatory, cholinergic, oxidative stress, and gut floral indicators. Furthermore, the absorption, distribution, metabolism, excretion, and toxicity (ADMET) and drug-likeness properties of BTL-I were studied by the in silico tool ADMETlab.

Results

BTL-I dose-dependently ameliorated AlCl₃-induced cognitive deficits in zebrafish. While AlCl₃ treatment elevated the levels of central and peripheral proinflammatory cytokines, increased AChE activity, and lowered GSH in the brains of zebrafish, these effects, except GSH reduction, were reversed by 25–100 mg/kg BTL-I administration. Besides, 16S rDNA high-throughput sequencing of the intestinal flora of zebrafish showed that AlCl₃ decreased Gram-positive bacteria and increased proinflammatory Gram-negative bacteria, while BTL-I contributed to maintaining the predominance of beneficial Gram-positive bacteria. Moreover, the in silico analysis indicated that BTL-I exhibits acceptable drug-likeness and ADMET profiles.

Conclusions

The present findings suggest that BTL-I is a potential therapeutic agent for preventing CNS deficits caused by inflammation, neurotoxicity, and gut flora imbalance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02403-3.

Natural Polyphyllins (I, II, D, VI, VII) Reverses Cancer Through Apoptosis, Autophagy, Mitophagy, Inflammation, and Necroptosis

Cancer is the second leading cause of mortality worldwide. Conventional therapies, including surgery, radiation, and chemotherapy, have limited success because of secondary resistance. Therefore, safe, non-resistant, less toxic, and convenient drugs are urgently required. Natural products (NPs), primarily sourced from medicinal plants, are ideal for cancer treatment because of their low toxicity and high success. NPs cure cancer by regulating different pathways, such as PI3K/AKT/mTOR, ER stress, JNK, Wnt, STAT3, MAPKs, NF-kB, MEK-ERK, inflammation, oxidative stress, apoptosis, autophagy, mitophagy, and necroptosis. Among the NPs, steroid saponins, including polyphyllins (I, II, D, VI, and VII), have potent pharmacological, analgesic, and anticancer activities for the induction of cytotoxicity. Recent research has demonstrated that polyphyllins (PPs) possess potent effects against different cancers through apoptosis, autophagy, inflammation, and necroptosis. This review summarizes the available studies on PPs against cancer to provide a basis for future research.

A Sulfated Polysaccharide from Saccharina japonica Suppresses LPS-Induced Inflammation Both in a Macrophage Cell Model via Blocking MAPK/NF-κB Signal Pathways In Vitro and a Zebrafish Model of Embryos and Larvae In Vivo

Inflammation is a complicated host-protective response to stimuli and toxic conditions, and is considered as a double-edged sword. A sulfated Saccharinajaponica polysaccharide (LJPS) with a sulfate content of 9.07% showed significant inhibitory effects against lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 macrophage cells and zebrafish. Its chemical and structural properties were investigated via HPLC, GC, FTIR, and NMR spectroscopy. In vitro experiments demonstrated that LJPS significantly inhibited the generation of nitric oxide (NO) and prostaglandin E2 (PGE2) via the downregulation of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression and suppressed pro-inflammatory cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-1β production via the nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signal pathways in LPS-induced RAW 264.7 cells. Moreover, LJPS showed strong protective effects against LPS-induced inflammatory responses in zebrafish, increasing the survival rate, reducing the heart rate and yolk sac edema size, and inhibiting cell death and the production of intracellular reactive oxygen species (ROS) and NO. Its convenience for large-scale production and significant anti-inflammatory activity indicated the potential application of LJPS in functional foods, cosmetics, and pharmaceutical industries.

Fucoidan from acid-processed Hizikia fusiforme attenuates oxidative damage and regulate apoptosis

We had observed in our previous study that the active fucoidan (JHCF4), isolated from the crude fucoidan in acid-processed Hizikia fusiforme, possessed an anticancer effect. In this study, the antioxidant effect of JHCF4 was evaluated. Among the fractions, JHCF4 showed the highest scavenging activity against 2, 2-diphenyl-1-picrylhydrazyl (DPPH), alkyl, and hydroxyl radicals, as well as protective effect against reactive oxygen species (ROS) in 2, 2'-azobis (2-amidinopropane) dihydrochloride (AAPH)-treated Vero cells. Furthermore, JHCF4 showed a protective activity against AAPH-induced apoptosis, as observed by nuclear staining with Hoechst 33342. Our results showed that JHCF4 can up-regulate Bcl-xL, down-regulate Bax and cleave caspase-3 with increased concentrations in AAPH-induced Vero cells. JHCF4 induced anti-apoptosis via a mitochondria-mediated pathway. Additionally, JHCF4 was selected for further in vivo screening in a zebrafish model, which markedly decreased ROS generation and lipid peroxidation. Thus, JHCF4 showed a potential protective activity against AAPH-induced ROS both in vitro and in the zebrafish model.

Immune-related genes response to stimulation of miR-155 overexpression in CIK (ctenopharyngodon idella kidney) cells and zebrafish

MiR-155 regulates the development of germinal-center and the generation of immunoglobulin class-switched plasma cells. However, whether miR-155 is involved in immune response in fish is still unclear. Here, CIK cells transfected with miR-155 overexpressed plasmid inhibited mRNA expression of mIg and Rag2 (P < 0.05). Interestingly, mIg was predicted as a potential target gene of miR-155 by RNAhybrid, with a putative binding site in its CDS. Further, mIg luciferase reporter vectors with successive deletions of mIg cDNA sequence were constructed and dual luciferase reporter assay showed that vectors containing the sequence from 318 to 347 in CDS exhibited lower relative luciferase activity than others without predicted binding region (P < 0.05), which indicated mIg is the target gene of miR-155 and reveal bona fide targeted binding site of mIg for miR-155 in fish. In vivo, the zebrafish were respectively injected with miR-155 overexpressed and empty vector, and showed that miR-155 efficiently expressed in zebrafish (P < 0.01), which consistently decreased mRNA level of immune-related genes, including mIg (P < 0.01), sIg (P < 0.05), AID (P < 0.01), PU.1 (P < 0.05) and Rag2 (P < 0.05) at d 3 and d 6 post injection, comparing to control. Collectively, this work indicates that overexpression of miR-155 suppresses the mRNA level of immune-related genes in CIK cells and zebrafish, and mIg is a novel target gene of miR-155 in fish. These findings provide an insight into the miR-155 modulating adaptive immunity in grass carp and zebrafish.

Zebrafish are Resistant to Staphylococcus aureus Endophthalmitis

Gram-positive bacteria remain the leading cause of endophthalmitis, a blinding infectious disease of the eye. Murine models have been widely used for understanding the pathogenesis of bacterial endophthalmitis. In this study, we sought to develop an alternative zebrafish (Danio rerio) model for Staphylococcus aureus and compare the disease pathobiology to a murine model. Endophthalmitis was induced in zebrafish and C57BL/6 mice through the intravitreal injection of S. aureus. Disease progression was monitored by assessing corneal haze, opacity, bacterial burden, and retinal histology. Our results demonstrated that, unlike the murine models, zebrafish maintained ocular integrity, corneal transparency, and retinal architecture. We found that the zebrafish was capable of clearing S. aureus from the eye via transport through retinal vessels and the optic nerve and by mounting a monocyte/macrophage response beginning at 8 hour post-infection (hpi). The bacterial burden increased up to 8 hpi and significantly decreased thereafter. An assessment of the innate retinal response revealed the induced expression of Il-1β and Il-6 transcripts. Collectively, our study shows that unlike the murine model, zebrafish do not develop endophthalmitis and rapidly clear the pathogen. Hence, a better understanding of the zebrafish protective ocular innate response may provide new insights into the pathobiology of bacterial endophthalmitis.

Is related the hematopoietic stem cells differentiation in the Nile tilapia with GABA exposure?

The signaling mediated by small non-proteinogenic molecules, which probably have the capacity to serve as a bridge amongst complex systems is one of the most exiting challenges for the study. In the current report, stem cells differentiation of the immune system in Nile tilapia treated with sub-basal doses of GABA evaluated as c-kit⁺ and Sca-1⁺ cells disappearance on pronephros, thymus, spleen and peripheral blood mononuclear cells by flow cytometry was assessed. Explanation of biological response was performed by molecular docking approach and multiparametric analysis. Stem cell differentiation depends on a delicate balance of negative and positive interactions of this neurotransmitter with receptors and transcription factors involved in this process. This in turn depends on the type of interaction with hematopoietic niche to differentiate into primordial, early or late hematopoiesis as well as from the dose delivery. In fish treated with the low doses of GABA (0.1% over basal value) primordial hematopoiesis is regulated by interaction of glutamate (Glu) with the Ly-6 antigen. Early hematopoiesis was influenced by the bond of GABA near or adjacent to turns of FLTR3-Ig-IV domain. During late hematopoiesis, negative regulation by structural modifications on PU.1/IRF-4 complex, IL-7Rα and GM-CSFR mainly prevails. Results of molecular docking were in agreement with the percentages of the main blood cells lineages estimated in pronephros by flow cytometry. Current study provides the first evidences about the role of inhibitory and excitatory neurotransmitters such as GABA and Glu, respectively with the most transcriptional factors and receptors involved on hematopoiesis in adult Nile tilapia.

Zebrafish and Medaka: Two Teleost Models of T-Cell and Thymic Development

Over the past two decades, studies have demonstrated that several features of T-cell and thymic development are conserved from teleosts to mammals. In particular, works using zebrafish (Danio rerio) and medaka (Oryzias latipes) have shed light on the cellular and molecular mechanisms underlying these biological processes. In particular, the ease of noninvasive in vivo imaging of these species enables direct visualization of all events associated with these processes, which are, in mice, technically very demanding. In this review, we focus on defining the similarities and differences between zebrafish and medaka in T-cell development and thymus organogenesis; and highlight their advantages as two complementary model systems for T-cell immunobiology and modeling of human diseases.

Loss of runx1 function results in B cell immunodeficiency but not T cell in adult zebrafish

Transcription factor RUNX1 holds an integral role in multiple-lineage haematopoiesis and is implicated as a cofactor in V(D)J rearrangements during lymphocyte development. Runx1 deficiencies resulted in immaturity and reduction of lymphocytes in mice. In this study, we found that runx1^W84X/W84X mutation led to the reduction and disordering of B cells, as well as the failure of V(D)J rearrangements in B cells but not T cells, resulting in antibody-inadequate-mediated immunodeficiency in adult zebrafish. By contrast, T cell development was not affected. The decreased number of B cells mainly results from excessive apoptosis in immature B cells. Disrupted B cell development results in runx1^W84X/W84X mutants displaying a similar phenotype to common variable immunodeficiency—a primary immunodeficiency disease primarily characterized by frequent susceptibility to infection and deficient immune response, with marked reduction of antibody production of IgG, IgA and/or IgM. Our studies demonstrated an evolutionarily conserved function of runx1 in maturation and differentiation of B cells in adult zebrafish, which will serve as a valuable model for the study of immune deficiency diseases and their treatments.

In Vitro and In Vivo Anti-Inflammatory Effects of Polyphyllin VII through Downregulating MAPK and NF-κB Pathways

Background: Polyphyllin VII (PP7), a steroidal saponin from Paris polyphylla, has been found to exert strong anticancer activity. Little is known about the anti-inflammatory property of PP7. In this study, the anti-inflammatory activity and its underlying mechanisms of PP7 were evaluated in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and in multiple animal models. Methods: The content of nitric oxide (NO) was determined by spectrophotometry. The levels of prostaglandin E2 (PGE₂) and cytokines were measured by enzyme-linked immunosorbent assay (ELISA) assay. The mRNA expression of pro-inflammatory genes was determined by qPCR. The total and phosphorylated protein levels were examined by Western blotting. The in vivo anti-inflammatory activities were evaluated by using mouse and zebrafish models. Results: PP7 reduced the production of NO and PGE₂ and the protein and mRNA expressions of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and enzymes (inducible NO synthase [iNOS], cyclooxygenase-2 [COX-2], and Matrix metalloproteinase-9 [MMP-9]) in LPS-induced RAW264.7 cells by suppressing the NF-κB and MAPKs pathways. Notably, PP7 markedly inhibited xylene-induced ear edema and cotton pellet-induced granuloma formation in mice and suppressed LPS and CuSO₄-induced inflammation and toxicity in zebrafish embryos. Conclusion: This study demonstrates that PP7 exerts strong anti-inflammatory activities in multiple in vitro and in vivo models and suggests that PP7 is a potential novel therapeutic agent for inflammatory diseases.

Mussel (Mytilus coruscus) Water Extract Containing Taurine Prevents LPS-Induced Inflammatory Responses in Zebrafish Model

Mussel (Mytilus coruscus) water extract had strong anti-inflammatory activities, but the effects and its mechanisms of mussel on anti-inflammatory properties in vivo remain to be determined. This study, therefore, was designed to investigate anti-inflammatory activities of mussel water extract containing a large amounts of taurine (151.96 nmol/mg) using the lipopolysaccharide (LPS)-induced inflammatory zebrafish model. In this study, mussel water extract containing taurine shows potent protective effects against the cell death stimulated by LPS exposure in zebrafish embryos. In addition, zebrafish subjected to LPS treatment exhibited significantly increased reactive oxygen species (ROS) and nitric oxide (NO) levels. However, mussel water extract markedly suppressed LPS-induced ROS and NO production. Our results indicate that mussel water extract attenuated inflammation by inhibiting the LPS-induced intracellular ROS and NO production in zebrafish embryos. These findings could demonstrate the anti-inflammatory activity of mussel water extract containing taurine, which might have a protective effects on inflammatory diseases.

Effects of Sex Steroids on Fish Leukocytes

In vertebrates, in addition to their classically reproductive functions, steroids regulate the immune system. This action is possible mainly due to the presence of steroid receptors in the different immune cell types. Much evidence suggests that the immune system of fish is vulnerable to xenosteroids, which are ubiquitous in the aquatic environment. In vivo and in vitro assays have amply demonstrated that oestrogens interfere with both the innate and the adaptive immune system of fish by regulating the main leukocyte activities and transcriptional genes. They activate nuclear oestrogen receptors and/or G-protein coupled oestrogen receptor. Less understood is the role of androgens in the immune system, mainly due to the complexity of the transcriptional regulation of androgen receptors in fish. The aim of this manuscript is to review our present knowledge concerning the effect of sex steroid hormones and the presence of their receptors on fish leukocytes, taking into consideration that the studies performed vary as regard the fish species, doses, exposure protocols and hormones used. Moreover, we also include evidence of the probable role of progestins in the regulation of the immune system of fish.

Cadmium exposure exacerbates severe hyperlipidemia and fatty liver changes in zebrafish via impairment of high-density lipoproteins functionality

Cadmium (Cd) is a heavy metal with several toxicities that have destructive effect on most organ systems. However, its toxic effects on human lipoproteins are largely remained unknown especially in hyperlipidemic zebrafish model. Treatment of human high-density lipoprotein (HDL) with cadmium chloride (CdCl₂, final 12 and 24μM) caused spontaneous formation of multimeric apoA-I as well as increased production of glycated extent products. Cd-HDL₃ accelerated uptake of oxidized LDL (oxLDL) into macrophages and induced severe senescence in human dermal fibroblast (HDF) cells. Microinjection of Cd-HDL₃ into zebrafish embryos resulted in acute embryonic toxicity with high mortality. Exposure of zebrafish embryos to water containing CdCl₂ (final 12 and 24μM) caused early embryonic death along with increased production of oxidized products and impairment of skeletal development. Consumption of CdCl₂ (12 and 24μM) by zebrafish for 4weeks resulted in severe elevation of plasma total cholesterol (TC) and triglyceride (TG) levels as well as cholesteryl ester (CE) transfer activity. Furthermore, consumption of CdCl₂ resulted in acceleration of fatty liver changes and increased production of reactive oxygen species (ROS). In conclusion, CdCl₂ caused structural modification of HDL₃ and impaired the beneficial functions of HDL₃, including anti-oxidation, anti-atherosclerosis, and anti-senescence effects. Consumption of CdCl₂ also resulted in exacerbated hyperlipidemia and fatty liver changes in zebrafish via enhancement of cholesteryl ester transfer protein (CETP) activity.

The bias of experimental design, including strain background, in the determination of critical Streptococcus suis serotype 2 virulence factors

Streptococcus suis serotype 2 is an important porcine bacterial pathogen and emerging zoonotic agent mainly responsible for sudden death, septic shock, and meningitis. However, serotype 2 strains are genotypically and phenotypically heterogeneous. Though a multitude of virulence factors have been described for S. suis serotype 2, the lack of a clear definition regarding which ones are truly “critical” has created inconsistencies that have only recently been highlighted. Herein, the involvement of two factors previously described as being critical for S. suis serotype 2 virulence, whether the dipeptidyl peptidase IV and autolysin, were evaluated with regards to different ascribed functions using prototype strains belonging to important sequence types. Results demonstrate a lack of reproducibility with previously published data. In fact, the role of the dipeptidyl peptidase IV and autolysin as critical virulence factors could not be confirmed. Though certain in vitro functions may be ascribed to these factors, their roles are not unique for S. suis, probably due to compensation by other factors. As such, variations and discrepancies in experimental design, including in vitro assays, cell lines, and animal models, are an important source of differences between results. Moreover, the use of different sequence types in this study demonstrates that the role attributed to a virulence factor may vary according to the S. suis serotype 2 strain background. Consequently, it is necessary to establish standard experimental designs according to the experiment and purpose in order to facilitate comparison between laboratories. Alongside, studies should include strains of diverse origins in order to prevent erroneous and biased conclusions that could affect future studies.

Transgenic overexpression of BAFF regulates the expression of immune-related genes in zebrafish, Danio rerio

The B-cell activating factor (BAFF) is a member of tumour necrosis factor (TNF) superfamily that specifically regulates B lymphocyte proliferation and survival. Excess BAFF leads to overproduction of antibodies for secretion, anti-dsDNA antibodies and a lupus-like syndrome in mice. To investigate whether transgenic overexpression of the zebrafish BAFF leads to immunoglobulin changes and/or early maturing of the immune system, a Tol2-GFP-2A-BAFF/His recombinant plasmid was constructed by inserting a 2A peptide between the green fluorescent protein (GFP) and BAFF sequences. Functional GFP and BAFF proteins were expressed separately and confirmed in HeLa cells. The relative expression of immune-related genes (IgLC-1, IgLC-2, IgLC-3, IgD, IgM and IL-4), early lymphoid markers (Ikaros, Rag-1 and TCRAC), and the protooncogene Bcl-2 were evaluated by quantitative polymerase chain reaction (PCR) in F0 founder of transgenic zebrafish juveniles and adults. Ectopic expression of BAFF in adults was confirmed using Western blots and was shown to upregulate IgLC-1, IgLC-2, IgD, IgM, IgZ/T, Ikaros, Rag-1, TCRAC, IL-4 and Bcl-2 expression in juveniles on day 21 and IgLC-1, IgLC-2, IgD, IgM,IgZ/T, Rag-1, TCRAC and Bcl-2 expression in zebrafish three months postfertilization. The relative titers of specific IgM against Edwardsiella tarda WED were assessed using modified enzyme-linked immunosorbent assay (ELISA) with the whole body homogenate of zebrafish and demonstrated a significant increase in BAFF-transgenic group. Therefore, our findings provided novel insight into further exploration of modulating adaptive immunity and studying autoimmune diseases caused by regulating BAFF.

Breast Milk from Smokers Contains Less Cholesterol and Protein and Smaller Size of Apolipoprotein A-I Resulting in Lower Zebrafish Embryo Survivability

BACKGROUND

To determine the quality of breast milk (BM), we compared the functions of BM from ex-smokers and nonsmokers.

SUBJECTS AND METHODS

We analyzed the contents of lipids, glucose, and protein in BM from ex-smokers (10 cigarettes/day for 13 ± 3 years) as well as infant formula.

RESULTS

Nonsmokers' BM showed 2.4- and 1.4-fold higher cholesterol and protein contents, respectively, than BM from smokers. Infant formula contained almost no cholesterol, but did show remarkably higher glucose and triglyceride levels than BM. Microinjection of BM (50 nL) from nonsmokers and smokers into zebrafish embryos resulted in 59% and 44% survival, respectively, whereas formula injection resulted in 31% survival. The higher cholesterol and protein contents of BM were directly correlated with higher embryo survivability, suggesting that cholesterol content is directly and critically associated with growth of neonate infants. Smokers' BM contained smaller-sized apolipoproteinA-I (apoA-I) (24.4 ± 0.2 kDa) than BM from nonsmokers (26.7 ± 0.4 kDa), suggesting that putative modification and cleavage occurred in apoA-I. BM containing higher molecular weight apoA-I resulted in higher embryo survivability.

CONCLUSIONS

Smoking before pregnancy can affect the composition and quality of BM, resulting in almost complete loss of cholesterol and protein, especially lactoferrin, lactalbumin, and apoA-I, accompanied by proteolytic degradation. These impairment effects of BM are associated with elevation of oxidative stress and lower embryo survivability.

Anti-inflammatory Effects of Galactose-Taurine Sodium Salt: A Taurine Derivate in Zebrafish In Vivo Model

Taurine, the plentiful amino acids in mammalian cells exerts various biological activities including antioxidant and anti-inflammatory effects. Inflammation can cause several diseases such as cancer, heart disease, rheumatoid arthritis and immune system reactions. Here, we investigated anti-inflammatory effects of Galactose-Taurine sodium salt (Gal-Tau), a newly synthesized taurine derivate in LPS-stimulated zebrafish embryos in vivo model. The result showed that Gal-Tau improved the survival rate and the edema in LPS-treated zebrafish embryos. Also, Gal-Tau effectively reduced the productions of nitric oxide (NO), reactive oxygen species (ROS) and cell death induced by LPS in zebrafish embryos. In addition, Gal-Tau regulated the expression levels of inflammatory mediators such as inducible NOS (iNOS) and cycloxygenase 2 (COX-2) as well as IL-6 and TNF-α, inflammatory cytokines known as important key mediators of inflammation. Taken together, this study first indicates that Gal-Tau could be considered as an effective anti-inflammatory material with its anti-inflammatory activity.

The zebrafish as a model to study intestinal inflammation

Starting out as a model for developmental biology, during the last decade, zebrafish have also gained the attention of the immunologists and oncologists. Due to its small size, high fecundity and full annotation of its genome, the zebrafish is an attractive model system. The fact that fish are transparent early in life combined with the growing list of immune cell reporter fish, enables in vivo tracking of immune responses in a complete organism. Since zebrafish develop ex utero from a fertilized egg, immune development can be monitored from the start of life. Given that several gut functions and immune genes are conserved between zebrafish and mammals, the zebrafish is an interesting model organism to investigate fundamental processes underlying intestinal inflammation and injury. This review will first provide some background on zebrafish intestinal development, bacterial colonization and immunity, showing the similarities and differences compared to mammals. This will be followed by an overview of the existing models for intestinal disease, and concluded by future perspectives in light of the newest technologies and insights.

Granulomatous Uveitis Associated with Vaccination in the Atlantic Salmon

This study addressed histologic and immunopathologic changes in ocular tissues and investigated the distribution of major histocompatibility class II (MHC class II)-positive cells in Atlantic salmon ( Salmo salar) suffering from severe postvaccination disease. Twenty-nine fish with generalized inflammation, probably a result of vaccination, were investigated. One individual that had escaped vaccination was included in the study. Material was investigated by cultivation methods for fungi and bacteria. Histology using conventional staining procedures and immunohistochemistry with antisera against MHC class II β chain were performed. No growth was observed from the cultivation investigations. Histology revealed occlusion of the lumen in the larger choroid vessels and in the choriocapillaris, inflammatory infiltrations and loss of structure in the choroid rete, and, in some cases, aggregations of multinucleated giant cells (MGC) and Splendore-Hoeppli material. Immunohistochemistry demonstrated massive MHC class II+ cellular infiltrations in the uveal tract. Such infiltrations were also seen in the ventral ciliary cleft, a condition that is associated with glaucoma. Immunoreactive cells included dendritelike cells, epithelioid cells, and MGCs. The endothelia of smaller vessels were frequently MHC class II+, and immunoreactive infiltrations were seen in the optic nerve in several individuals. No pathologic changes were detected in the unvaccinated individual. In conclusion, generalized inflammatory reactions in fish may lead to severe ocular inflammation, occlusion of uveal vessels, and perivascular changes with MHC class II+ upregulation in cells in the uveal tract and optic nerve.

Recent findings on vertebrate developmental immunity using the zebrafish model

To grant survival against sterile or microbe induced inflammation, all animals rely on correct immune system functioning. The development of immunity occurs in vertebrates during embryogenesis in a process called hematopoiesis, which is characterized by the formation of blood cellular components such as embryonic erythrocytes and primitive macrophages. These cells are formed in a sterile environment from a rare subset of pluripotent hematopoietic stem cells (HSC) during a brief period of the primitive hematopoietic wave. Diverse signals, like Notch, are indispensable in HSC emergence and differentiation. However, to successfully replicate the process in vitro using pluripotent precursors, the full set of required signals is still a matter of debate. Among the latest findings, proinflammatory signals produced by transient primitive myelocites in zebrafish have been seen to act as essential mediators in establishing the HSC program of the adult vertebrate hematopoietic system. In this regard, the zebrafish immune model has emerged as a feasible live vertebrate model for examining developmental immunity and related host-microbe interactions, both at the molecular and cellular level. Thus, using the zebrafish embryo, this review summarizes recent findings, on the signals required for immune development and further maturation of the system, in a context where no adaptive immune response has yet been developed.

T Cells in Fish

Cartilaginous and bony fish are the most primitive vertebrates with a thymus, and possess T cells equivalent to those in mammals. There are a number of studies in fish demonstrating that the thymus is the essential organ for development of T lymphocytes from early thymocyte progenitors to functionally competent T cells. A high number of T cells in the intestine and gills has been reported in several fish species. Involvement of CD4⁺ and CD8α⁺ T cells in allograft rejection and graft-versus-host reaction (GVHR) has been demonstrated using monoclonal antibodies. Conservation of CD4⁺ helper T cell functions among teleost fishes has been suggested in a number studies employing mixed leukocyte culture (MLC) and hapten/carrier effect. Alloantigen- and virus-specific cytotoxicity has also been demonstrated in ginbuna and rainbow trout. Furthermore, the important role of cell-mediated immunity rather than humoral immunity has been reported in the protection against intracellular bacterial infection. Recently, the direct antibacterial activity of CD8α⁺, CD4⁺ T-cells and sIgM⁺ cells in fish has been reported. In this review, we summarize the recent progress in T cell research focusing on the tissue distribution and function of fish T cells.

Understanding the complexities of Salmonella-host crosstalk as revealed by in vivo model organisms

Foodborne infections caused by non-typhoidal Salmonellae, such as Salmonella enterica serovar Typhimurium (ST), pose a major challenge in the developed and developing world. With constant rise of drug-resistant strains, understanding the epidemiology, microbiology, pathogenesis and host-pathogen interactions biology is a mandatory requirement to enable health systems to be ready to combat these illnesses. Patient data from hospitals, at least from some parts of the world, have aided in epidemiological understanding of ST-mediated disease. Most of the other aspects connected to Salmonella-host crosstalk have come from model systems that offer convenience, genetic tractability and low maintenance costs that make them extremely valuable tools. Complex model systems such as the bovine model have helped in understanding key virulence factors needed for infection. Simple systems such as fruit flies and Caenorhabditis elegans have aided in identification of novel virulence factors, host pathways and mechanistic details of interactions. Some of the path-breaking concepts of the field have come from mice model of ST colitis, which allows genetic manipulations as well as high degree of similarity to human counterpart. Together, they are invaluable for correlating in vitro findings of ST-induced disease progression in vivo. The current review is a compilation of various advances of ST-host interactions at cellular and molecular levels that has come from investigations involving model organisms.

Zebrafish as a model for leukemia and other hematopoietic disorders

Zebrafish is an established model for the study of vertebrate development, and is especially amenable for investigating hematopoiesis, where there is strong conservation of key lineages, genes, and developmental processes with humans. Over recent years, zebrafish has been increasingly utilized as a model for a range of human hematopoietic diseases, including malignancies. This review provides an overview of zebrafish hematopoiesis and describes its application as a model of leukemia and other hematopoietic disorders.

Oleuropein suppresses LPS-induced inflammatory responses in RAW 264.7 cell and zebrafish

Oleuropein is one of the primary phenolic compounds present in olive leaf. In this study, the anti-inflammatory effect of oleuropein was investigated using lipopolysaccharide (LPS)-stimulated RAW 264.7 and a zebrafish model. The inhibitory effect of oleuropein on LPS-induced NO production in macrophages was supported by the suppression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In addition, our enzyme immunoassay showed that oleuropein suppressed the release of pro-inflammatory cytokines such as interleukin-1β (IL-1β) and interleukin-6 (IL-6). Oleuropein inhibited the translocation of p65 by suppressing phosphorylation of inhibitory kappa B-α (IκB-α). Oleuropein also decreased activation of ERK1/2 and JNK, which are associated with LPS-induced inflammation, and its downstream gene of AP-1. Furthermore, oleuropein inhibited LPS-stimulated NO generation in a zebrafish model. Taken together, our results demonstrated that oleuropein could reduce inflammatory responses by inhibiting TLR and MAPK signaling, and may be used as an anti-inflammatory agent.

The involvement of cholesterol in sepsis and tolerance to lipopolysaccharide highlighted by the transcriptome analysis of zebrafish (Danio rerio)

Septic shock is the most common cause of death in intensive care units due to an aggressive inflammatory response that leads to multiple organ failure. However, a lipopolysaccharide (LPS) tolerance phenomenon (a nonreaction to LPS), is also often described. Neither the inflammatory response nor the tolerance is completely understood. In this work, both of these responses were analyzed using microarrays in zebrafish. Fish that were 4 or 6 days postfertilization (dpf) and received a lethal dose (LD) of LPS exhibited 100% mortality in a few days. Their transcriptome profile, even at 4 dpf, resembled the profile in humans with severe sepsis. Moreover, we selected 4-dpf fish to set up a tolerance protocol: fish treated with a nonlethal concentration of Escherichia coli LPS exhibited complete protection against the LD of LPS. Most of the main inflammatory molecules described in mammals were represented in the zebrafish microarray experiments. Additionally and focusing on this tolerance response, the use of cyclodextrins may mobilize cholesterol reservoirs to decrease mortality after a LD dose of LPS. Therefore, it is possible that the use of the whole animal could provide some clues to enhance the understanding of the inflammatory/tolerance response and to guide drug discovery.

Complement system in zebrafish

Zebrafish is recently emerging as a model species for the study of immunology and human diseases. Complement system is the humoral backbone of the innate immune defense, and our knowledge as such in zebrafish has dramatically increased in the recent years. This review summarizes the current research progress of zebrafish complement system. The global searching for complement components in genome database, together with published data, has unveiled the existence of all the orthologues of mammalian complement components identified thus far, including the complement regulatory proteins and complement receptors, in zebrafish. Interestingly, zebrafish complement components also display some distinctive features, such as prominent levels of extrahepatic expression and isotypic diversity of the complement components. Future studies should focus on the following issues that would be of special importance for understanding the physiological role of complement components in zebrafish: conclusive identification of complement genes, especially those with isotypic diversity; analysis and elucidation of function and mechanism of complement components; modulation of innate and adaptive immune response by complement system; and unconventional roles of complement-triggered pathways.

Knockdown of PU.1 mRNA and AS lncRNA regulates expression of immune-related genes in zebrafish Danio rerio

The transcription factor PU.1 plays a key role in the development of immune system. Recent evidence demonstrated bidirectional transcription and a sense/antisense transcriptional regulatory manner in PU.1 locus. However, the effect of PU.1 mRNA and its antisense long non-coding RNA (AS lncRNA) on adaptive immunity in vivo is still not clear. In this study, we first confirmed the expression of PU.1 AS lncRNA by strand-specific RT-PCR in zebrafish. Additionally, we found that GFP was detected in zebrafish kidney using tissue smears after zebrafish was intraperitoneally injected with pLentiHI-PU.1 shRNA or pLentiHI-PU.1 AS shRNA for 2 days. Moreover, on day 0, 2 and 4, the levels of PU.1 and immune-related genes including TCRAC, Rag2, AID, IgLC-1, mIg, and sIg mRNAs were detected using real-time qPCR. The results showed that the levels of PU.1 and above 6 immune-related gene mRNAs were significantly downregulated on day 2 (P<0.05) and day 4 (P<0.01) by the treatment with the pLentiHI-PU.1 shRNA, whereas these genes were markedly upregulated by the treatment with the pLentiHI-PU.1 AS shRNA. Based on our results, we suggested that the effects of PU.1 transcripts including mRNA and AS lncRNA on immune-related gene expression in zebrafish were opposite. To our knowledge, this was the first report that a novel functional AS lncRNA in adaptive immunity was transcribed from the zebrafish PU.1 locus. Our findings provided novel insight into further exploration on modulating adaptive immunity by regulating PU.1 mRNA and AS lncRNA.

Identification of HIF-1α promoter and expression regulation of HIF-1α gene by LPS and hypoxia in zebrafish

The ubiquitously expressed hypoxia-inducible factor-1α (HIF-1α) acts as a key transcription factor in regulating metabolism, development, cellular survival, proliferation and pathology under hypoxia condition. Compared to mammals, fish are more vulnerable to hypoxia stress and contamination; however, the regulation of HIF-1α in fish remains obscure. In this study, zebrafish HIF-1α promoter was cloned and found to possess a CpG island located at -97 to +403, but the canonical TATA-box was absent. Aligning 240-bp HIF-1α proximal promoter region of zebrafish with other vertebrates showed more than 82 % identity with cyprinid fishes. Further luciferase analysis suggested that the minimal core promoter might locate at -134 to +97, and several putative transcription factor binding sites were found in this region by bioinformatic analysis. Moreover, it was shown that the zebrafish HIF-1α mRNA was significantly activated by 10 μg/mL lipopolysaccharide (LPS) under hypoxia condition and peaked at 8 h after treatment, suggesting LPS- and hypoxia-regulated zebrafish HIF-1α transcriptional activity in a synergistic pattern. This synergistic effect was closely related to the living environment of fish, indicating that this mechanism would be more conducive to fish survival.

Abundance of the Quorum-Sensing Factor Ax21 in Four Strains of Stenotrophomonas maltophilia Correlates with Mortality Rate in a New Zebrafish Model of Infection

Stenotrophomonas maltophilia is a Gram-negative pathogen with emerging nosocomial incidence. Little is known about its pathogenesis and the genomic diversity exhibited by clinical isolates complicates the study of pathogenicity and virulence factors. Here, we present a strategy to identify such factors in new clinical isolates of S. maltophilia, incorporating an adult-zebrafish model of S. maltophilia infection to evaluate relative virulence coupled to 2D difference gel electrophoresis to explore underlying differences in protein expression. In this study we report upon three recent clinical isolates and use the collection strain ATCC13637 as a reference. The adult-zebrafish model shows discrimination capacity, i.e. from very low to very high mortality rates, with clinical symptoms very similar to those observed in natural S. maltophilia infections in fish. Strain virulence correlates with resistance to human serum, in agreement with previous studies in mouse and rat and therefore supporting zebrafish as a replacement model. Despite its clinical origin, the collection strain ATCC13637 showed obvious signs of attenuation in zebrafish, with null mortality. Multilocus-sequence-typing analysis revealed that the most virulent strains, UV74 and M30, exhibit the strongest genetic similitude. Differential proteomic analysis led to the identification of 38 proteins with significantly different abundance in the three clinical strains relative to the reference strain. Orthologs of several of these proteins have been already reported to have a role in pathogenesis, virulence or resistance mechanisms thus supporting our strategy. Proof of concept is further provided by protein Ax21, whose abundance is shown here to be directly proportional to mortality in the zebrafish infection model. Indeed, recent studies have demonstrated that this protein is a quorum-sensing-related virulence factor.

Methylthioadenosine/S-adenosylhomocysteine nucleosidase (Pfs) of Staphylococcus aureus is essential for the virulence independent of LuxS/AI-2 system

Staphylococcus aureus is a major cause of infectious morbidity and mortality in both community and hospital settings. The bacterium continues to cause diverse invasive, life-threatening infections, such as pneumonia, endocarditis, and septicemia. Methylthioadenosine/S-adenosylhomocysteine nucleosidase (Pfs) is predicted to be an important enzyme involved in methylation reactions, polyamine synthesis, vitamin synthesis, and quorum sensing pathways. For the first time, we demonstrate that Pfs is essential for the virulence of S. aureus. The pfs mutant strain, as compared to the isogenic wild type, displayed a decreased production of extracellular proteases, which was correlated with a dramatic decrease in the expression of the sspABC operon and a moderate decrease of aur expression. The mouse model of sepsis and subcutaneous abscesses indicated that the pfs mutant strain displayed highly impaired virulence compared to the isogenic wild type. The decreased virulence of the pfs mutant strain is in correspondence with its decreased proliferation in vivo, indicated with a real-time analysis in the transparent system of zebrafish embryos. These phenotypes of the pfs mutant strain are LuxS/AI-2 independent despite the essential role pfs plays in AI-2 production. Our data suggest that Pfs is a potential novel target for anti-infection therapy.

Identification of a novel collagen type І-binding protein from Streptococcus suis serotype 2

Streptococcus suis, a major pathogen of pigs, is an emerging zoonotic agent that causes meningitis and septic shock. cbp40 is a putative virulent gene that has been identified using suppression subtractive hybridization performed on the virulent S. suis serotype 2 strain HA9801 and the avirulent S. suis serotype 2 strain T15. Based on predicted protein features showing a shared conserved domain with the collagen-binding protein Cna of Staphylococcus aureus, Cbp40 is likely to function as a direct mediator of collagen adhesion. Here, the cbp40 gene was cloned and the recombinant protein purified. Western blotting using swine convalescent sera confirmed its role as an immunogenic protein. Collagen binding activity could be detected by western affinity blot and ELISA. Conversely, deletion of the cbp40 gene reduced bacterial adhesion to HEp-2 cells, capacity for biofilm formation, and virulence in a zebrafish infection model. The response of the bEnd.3 cell line to infection with the S. suis serotype 2 strain ZY05719 and the cbp40-knockout strain was evaluated using gene expression arrays. The differentially expressed genes were involved in inflammatory and immune responses, leukocyte adhesion and heterophilic cell adhesion. Collectively, these data suggest that Cbp40 plays an important role as an extracellular matrix adhesion protein that interacts with host cells during infection.

Functional complexity of the Leishmania granuloma and the potential of in silico modeling

In human and canine visceral leishmaniasis and in various experimental models of this disease, host resistance is strongly linked to efficient granuloma development. However, it is unknown exactly how the granuloma microenvironment executes an effective antileishmanial response. Recent studies, including using advanced imaging techniques, have improved our understanding of granuloma biology at the cellular level, highlighting heterogeneity in granuloma development and function, and hinting at complex cellular, temporal, and spatial dynamics. In this mini-review, we discuss the factors involved in the formation and function of Leishmania donovani-induced hepatic granulomas, as well as their importance in protecting against inflammation-associated tissue damage and the generation of immunity to rechallenge. Finally, we discuss the role that computational, agent-based models may play in answering outstanding questions within the field.

Anti-inflammatory effect of fucoidan extracted from Ecklonia cava in zebrafish model

Fucoidan extracted from Ecklonia cava had strong anti-inflammatory activities. However, the direct effects of fucoidan of E. cava on anti-inflammatory activities in vivo model remained to be determined. Therefore, the present study was designed to assess in vivo anti-inflammatory effect of fucoidan extracted from E. cava (ECF) using tail-cutting-induced and lipopolysaccharide (LPS)-stimulated zebrafish model. Treating zebrafish model with tail-cutting and LPS-treatment significantly increased the ROS and NO level. However, ECF inhibited this tail-cutting-induced and LPS-stimulated ROS and NO generation. These results show that ECF alleviated inflammation by inhibiting the ROS and NO generation induced by tail-cutting and LPS-treatment. In addition, ECF has a protective effect against the toxicity induced by LPS exposure in zebrafish embryos. This outcome could explain the potential anti-inflammatory activity of ECF, which might have a beneficial effect during the treatment of inflammatory diseases.

Alternative TEL-JAK2 fusions associated with T-cell acute lymphoblastic leukemia and atypical chronic myelogenous leukemia dissected in zebrafish

BACKGROUND

Chromosomal translocations resulting in alternative fusions of the human TEL (ETV6) and JAK2 genes have been observed in cases of acute lymphoblastic leukemia and chronic myelogenous leukemia, but a full understanding of their role in disease etiology has remained elusive. In this study potential differences between these alternative TEL-JAK2 fusions, including their lineage specificity, were investigated.

DESIGN AND METHODS

TEL-JAK2 fusion types derived from both T-cell acute lymphoblastic leukemia and atypical chronic myelogenous leukemia were generated using the corresponding zebrafish tel and jak2a genes and placed under the control of either the white blood cell-specific spi1 promoter or the ubiquitously-expressed cytomegalovirus promoter. These constructs were injected into zebrafish embryos and their effects on hematopoiesis examined using a range of molecular approaches. In addition, the functional properties of the alternative fusions were investigated in vitro.

RESULTS

Injection of the T-cell acute lymphoblastic leukemia-derived tel-jak2a significantly perturbed lymphopoiesis with a lesser effect on myelopoiesis in zebrafish embryos. In contrast, injection of the atypical chronic myelogenous leukemia-derived tel-jak2a resulted in significant perturbation of the myeloid compartment. These phenotypes were observed regardless of whether expressed in a white blood cell-specific or ubiquitous manner, with no overt cellular proliferation outside of the hematopoietic cells. Functional studies revealed subtle differences between the alternative forms, with the acute lymphoblastic leukemia variant showing higher activity, but reduced downstream signal transducer and activator of transcription activation and decreased sensitivity to JAK2 inhibition. JAK2 activity was required to mediate the effects of both variants on zebrafish hematopoiesis.

CONCLUSIONS

This study indicates that the molecular structure of alternative TEL-JAK2 fusions likely contributes to the etiology of disease. The data further suggest that this class of oncogene exerts its effects in a cell lineage-specific manner, which may be due to differences in downstream signaling.

Tbl3 regulates cell cycle length during zebrafish development

The regulation of cell cycle rate is essential for the correct timing of proliferation and differentiation during development. Changes to cell cycle rate can have profound effects on the size, shape and cell types of a developing organ. We previously identified a zebrafish mutant ceylon (cey) that has a severe reduction in T cells and hematopoietic stem/progenitor cells (HSPCs). Here we find that the cey phenotype is due to absence of the gene transducin (beta)-like 3 (tbl3). The tbl3 homolog in yeast regulates the cell cycle by maintaining rRNA levels and preventing p53-induced cell death. Zebrafish tbl3 is maternally expressed, but later in development its expression is restricted to specific tissues. Tissues expressing tbl3 are severely reduced in cey mutants, including HSPCs, the retina, exocrine pancreas, intestine, and jaw cartilage. Specification of these tissues is normal, suggesting the reduced size is due to a reduced number of differentiated cells. Tbl3 MO injection into either wild-type or p53-/- mutant embryos phenocopies cey, indicating that loss of tbl3 causes specific defects in cey. Progression of both hematopoietic and retinal development is delayed beginning at 3 day post fertilization due to a slowing of the cell cycle. In contrast to yeast, reduction of Tbl3 causes a slowing of the cell cycle without a corresponding increase in p53 induced cell death. These data suggest that tbl3 plays a tissue-specific role regulating cell cycle rate during development.

Zebrafish: model for the study of inflammation and the innate immune response to infectious diseases

The zebrafish (Danio rerio) has been extensively used in biomedical research as a model to study vertebrate development and hematopoiesis and recently, it has been adopted into varied fields including immunology. After fertilization, larvae survive with only the innate immune responses because adaptive immune system is morphologically and functionally mature only after 4-6 weeks postfertilization. This temporal separation provides a suitable system to study the vertebrate innate immune response in vivo, independently from the adaptive immune response. The transparency of early life stages allows a useful real-time visualization. Adult zebrafish which have complete (innate and adaptative) immune systems offer also advantages over other vertebrate infection models: small size, relatively rapid life cycle, ease of breeding, and a growing list of molecular tools for the study of infectious diseases. In this review, we have tried to give some examples of the potential of zebrafish as a valuable model in innate immunity and inflammation studies.