Cortisol plays a role in the high environmental ammonia associated suppression of the immune response in zebrafish

Immunomodulation in Non-traditional Therapies for Methicillin-resistant Staphylococcus aureus (MRSA) Management

The rise of methicillin-resistant Staphylococcus aureus (MRSA) poses a significant challenge in clinical settings due to its ability to evade conventional antibiotic treatments. This overview explores the potential of immunomodulatory strategies as alternative therapeutic approaches to combat MRSA infections. Traditional antibiotics are becoming less effective, necessitating innovative solutions that harness the body's immune system to enhance pathogen clearance. Recent advancements in immunotherapy, including the use of antimicrobial peptides, phage therapy, and mechanisms of immune cells, demonstrate promise in enhancing the body's ability to clear MRSA infections. However, the exact interactions between these therapies and immunomodulation are not fully understood, underscoring the need for further research. Hence, this review aims to provide a broad overview of the current understanding of non-traditional therapeutics and their impact on immune responses, which could lead to more effective MRSA treatment strategies. Additionally, combining immunomodulatory agents with existing antibiotics may improve outcomes, particularly for immunocompromised patients or those with chronic infections. As the landscape of antibiotic resistance evolves, the development of effective immunotherapeutic strategies could play a vital role in managing MRSA infections and reducing reliance on traditional antibiotics. Future research must focus on optimizing these approaches and validating their efficacy in diverse clinical populations to address the urgent need for effective MRSA management strategies.

The growth performance and parasite load of angelfish juveniles Pterophyllum scalare kept at different stocking densities in two rearing systems

This study evaluated the growth performance and parasite load of angelfish juveniles Pterophyllum scalare kept at different stocking densities using two rearing systems. The experiment was conducted in a factorial design (4x2) with four stocking densities (0.1, 0.4, 0.7, and 1.0 g/L), two type of aquarium tanks (glass and ceramic aquariums), and four replicates. The experiment lasted 60 days using 148 juvenile fish (3.05 ± 0.09 g) randomly placed in 32 aquariums (50 L) equipped with filters and aeration. All fish received two meals a day ad libitum (8:00 and 16:00). Water quality parameters such as temperature, dissolved oxygen, pH, and total ammonia were measured. At the end of the experiment, all fish were measured and weighed to determine growth performance and then subjected to parasitological analysis. The data were analyzed with a two-way ANOVA with post-hoc Tukey test (p<0.05). No effects on growth performance at different stocking densities were observed. However, there was an increase in Capillaria pterophylli infestation in the high stocking density within ceramic aquariums. Thus, this study recommends the use of 1.0 g/L for the intensive aquaculture system of freshwater angelfish, and applying cleaning management to avoid parasite infestation, particularly in ceramic aquariums.

Clinico-pathological findings and expression of inflammatory cytokines, apoptosis, and oxidative stress-related genes draw mechanistic insights in Nile tilapia reared under ammonia-N exposure and Aeromonas hydrophila challenge

Fish diseases have a "stress-related" nature, whereas fish exposure to stressors will increase their susceptibility to infections. It was also noted that fish exposure to biotic and abiotic stressors would exaggerate the disease signs, elicit high mortalities, and cause severe economic losses. Motile aeromonad septicemia (MAS) is a major bacterial disease affecting a variety of finfish species throughout the globe and is caused by Aeromonas hydrophila. Herein, we have evaluated the impacts of ammonia-N stress and/or Nile tilapia challenge with pathogenic A. hydrophila on the clinical picture of MAS disease. Clinical signs, postmortem lesions, histoarchitectural changes, and gene transcription analysis were studied. Fish experimentally infected with A. hydrophila were exophthalmic and showed darkened skin. Moreover, opercular hyperemia, petechial hemorrhages, and gill congestion alongside dermal ulcerations were noticed in ammonia-exposed fish. On the other side, fish exposed to both stressors exhibited exophthalmia, corneal opacity, severe dropsy, and hemorrhagic dermal ulcerations. At the tissue levels, the histopathological lesions were exaggerated in the fish group exposed to ammonia stress and challenged with A. hydrophila than fish group exposed to each one alone. At the molecular levels, the mRNA expression analysis reveals significant upregulation of inflammatory cytokines such as interleukin-1 beta, CXC chemokine, and tumor necrosis factor-alpha in the kidney tissues of Nile tilapia exposed to ammonia and/or challenged with A. hydrophila. In a similar trend, the mRNA expression values of heat shock protein 70 (HSP70), oxidative stress related genes (SOD and CAT) and apoptosis-related genes (caspase 3, BAX, and cytochrome P450) were also increased in the hepatic tissues of fish exposed to singular or dual stressors. Interestingly, the highest expression levels of the above-mentioned genes were found in the fish group exposed to both stressors. Taken together, these findings indicate the occurrence of severe inflammatory and apoptotic changes in fish exposed to ammonia and infected with A. hydrophila more than each one alone. In contrast, there was a significant decrease in the expression values of the antioxidant enzyme glutathione-S-transferase (GST) in stressed fish, suggesting the occurrence of oxidative stress. This study will be helpful to draw mechanistic insights into the exposure of fish to ammonia stress and infection with A. hydrophila.

Inflammatory responses associated with hyposaline stress in gill epithelial cells of the spotted scat Scatophagus argus

The molecular processes of immune responses in mucosal tissues such as fish gills under environmental stress are poorly understood. In the present study, pro-inflammatory response under hyposaline stress and its regulation by cortisol/corticosteroid receptors (CRs) in gill epithelial cells of the spotted scat Scatophagus argus were analyzed. The fish were transferred to freshwater for 6 days (144 h) of acclimation. Following freshwater exposure, the cortisol concentration increased transiently before returning to the control level over time. mRNA expression of pro-inflammatory cytokines (TNF-a, IL-1b and IL-6) was stimulated by cortisol through CR signals at early stages of acclimation, but hyposaline stress inhibited their levels by the end of the experimental period. The transcriptional profile of anti-inflammatory cytokine IL-10 was quite different from these pro-inflammatory cytokines, and its value fluctuated within a narrow range during the experimental period. Full-length cDNAs of mineralocorticoid receptor (MR) and glucocorticoid receptor 1 (GR1) (different kinds of CRs) were cloned from the gills. Our results showed that MR and GR displayed mutually antagonistic effects during hyposaline stress. MR responded quickly at early stages, and its expression decreased with the drop of cortisol concentration. By contrast, GR expression was maintained at high levels after the acclimation of freshwater exposure. The tight coordination of GR and MR helps to shape the effects of stress on the immune system, which in turn, regulates the stress response. Our results confirm the interaction between endocrine and cytokine messengers and a clear difference in the sensitivity of GR and MR during the hyposaline challenge in gill epithelial cells of the spotted scat Scatophagus argus.

A Proposed Role for Pro-Inflammatory Cytokines in Damaging Behavior in Pigs

Sickness can change our mood for the worse, leaving us sad, lethargic, grumpy and less socially inclined. This mood change is part of a set of behavioral symptoms called sickness behavior and has features in common with core symptoms of depression. Therefore, the physiological changes induced by immune activation, for example following infection, are in the spotlight for explaining mechanisms behind mental health challenges such as depression. While humans may take a day off and isolate themselves until they feel better, farm animals housed in groups have only limited possibilities for social withdrawal. We suggest that immune activation could be a major factor influencing social interactions in pigs, with outbreaks of damaging behavior such as tail biting as a possible result. The hypothesis presented here is that the effects of several known risk factors for tail biting are mediated by pro-inflammatory cytokines, proteins produced by the immune system, and their effect on neurotransmitter systems. We describe the background for and implications of this hypothesis.

Modulation of inflammatory response by cortisol in the kidney of spotted scat (Scatophagus argus) in vitro under different osmotic stresses

Salinity changes on renal osmoregulation have often been investigated while the immune response of the kidney under osmotic stress is poorly understood in teleosts. Acute stress is generally associated with enhancement of circulating cortisol. The effects of osmotic stress on renal immune response and its regulation by cortisol deserve more attention. In the present study, the effects of exogenous cortisol treatment on the lipopolysaccharide (LPS)-induced immune response were analyzed in renal masses of Scatophagus argus under different osmotic stresses in vitro. mRNA expression of pro-inflammatory cytokines (TNF-α, IL1-β and IL-6) and immune-regulatory related genes (GR and SOCS1) was measured over a short course (15 h). Comprehensive analysis reveals that transcript abundances of pro-inflammatory cytokine genes such as TNF-α, IL-1β, and IL-6 induced by LPS, alone or in the combination of cortisol, are tightly associated with osmoregulation under acute osmotic stress. Our results showed that osmotic challenge could significantly enhance mRNA expression levels of pro-inflammatory cytokines in renal masses in vitro. Based on our analysis, it can be inferred that cortisol suppresses the magnitude of renal inflammatory response and attenuates LPS-induced immune response through GR signaling in the face of challenging environmental conditions.

Administration of commensal Shewanella sp. MR-7 ameliorates lipopolysaccharide-induced intestine dysfunction in turbot (Scophthalmus maximus L.)

This study was designed to evaluate whether the administration of commensal Shewanella sp. MR-7 (MR-7) could ameliorate lipopolysaccharide (LPS)-induced intestine dysfunction in turbot. Fish (body weight: 70.00 ± 2.00 g) were randomly divided into three groups including the control group treated with dough, the LPS group treated with dough plus LPS, and the LPS+MR-7 (LMR) group treated with dough plus LPS and MR-7. These three groups with 24 fish each were force-fed with 1 g dough daily for 7 continuous days. The results revealed that MR-7 administration ameliorated LPS-induced intestinal injury, showing higher intestinal villus and microvillus height. Further results showed that MR-7 could inhibit LPS-induced activation of TLR-NF-κB signaling thus maintaining the normal expression levels of cytokines and finally ameliorate the intestinal inflammatory response in turbot. Compared with the LPS group, LMR group had less goblet cells and lower mucin-2 expression level. Moreover, MR-7 restored LPS-induced down-regulation of tight junction protein-related gene expression (zonula occluden-1, occludin, tricellulin and claudin-3). Further investigations indicated that MR-7 partially counteracted LPS-induced changes in gut microbiota composition, enhanced the beneficial bacteria Lactobacillus and reduced the Pseudomonas, thus maintaining the overall microbiota balance. Taken together, the administration of MR-7 could effectively restore LPS-induced intestine function disorder in turbot by ameliorating inflammatory response, mucosal barrier dysfunction and microbiota dysbiosis.

Transcriptome analysis reveals benzotriazole ultraviolet stabilizers regulate networks related to inflammation in juvenile zebrafish (Danio rerio) brain

Benzotriazole ultraviolet stabilizers (BUVSs) are widely applied ultraviolet absorbing compounds in industrial materials and personal care products. Due to their ubiquitous use and reports of bio-accumulation in aquatic organisms, these compounds are significant environmental pollutants; however, data are limited for BUVSs toxicity. In this study, juvenile zebrafish (Danio rerio) were exposed to 4 commonly used BUVSs (UV-234, UV-326, UV-329, and UV-P) at one dose of 10 or 100 μg/L for 28 days. To characterize the underlying mechanisms of different BUVSs-induced toxicities, we performed global transcriptome sequencing (RNA-Seq) in the brain (100 μg/L). There were 390, 575, 483, and 470 differentially expressed genes (DEGs) detected following UV-234, UV-326, UV-329, and UV-P exposure at 100 μg/L, respectively. Only 59 genes were identified as DEGs following exposure to each of the BUVSs, suggesting that these chemicals can induce unique responses in fish. Noteworthy was that there were 81 common gene networks (~10%) identified following exposure to BUVSs, many of which were related to inflammation and immune function. Uniquely regulated pathways affected by different BUVSs included those related to mitochondrial respiration, interleukin 1/brain-damaging signaling, dopaminergic signaling, and adrenergic receptor cascades. Furthermore, quantitative PCR (qPCR) results revealed that mgst1 levels were increased in fish from the 100 μg/L UV-329 treatment, while the expression of pck2 was significantly down-regulated in fish from both the 10 and 100 μg/L UV-P treatment. Transcriptomic data suggest that BUVSs can alter mitochondrial bioenergetics, alter expression of a broad range of genes in the oxidative stress response, and can induce pathways related to the immune system in zebrafish brain.

Transcriptomic analysis of zebrafish (Danio rerio) embryos to assess integrated biotoxicity of Xitiaoxi River waters

Assessing the toxicity posed by mixtures of unknown chemicals to aquatic organisms is challenging. In this study, water samples from six cross-sections along the Xitiaoxi River Basin (XRB) were monthly or bimonthly collected in 2014. The year-period physiochemical parameters as well as one-month-water sample based acute biotoxicity tests showed that the river water quality of the year was generally in a good status. High performance liquid chromatography (HPLC) screening based on one-month-water samples suggested that the organic pollutants might be non-to-moderately-polar chemicals in very low concentrations. One-month-water sample based RNA-seq was performed to measure the mRNA differential expression profile of zebrafish larvae to furtherly explore the potential bioeffect and the spatial water quality change of the river. Result indicated that the number of deferentially expressed genes (DEGs) tended to increase along the downstream direction of the river. Gene ontology (GO) enrichment analysis implied that the key pollutants might mainly be the function disruptors of biological processes. Principle components analysis (PCA) combining with transcripts and one-month-water sample based physiochemical parameters indicated that the pollution might be similar at TP, DP and CTB sites while pollution homology existed on some extent between YBQ and JW sites. Although the water quality of the river had a complex time-space alternation during the year, and the one-month-data based RNA-seq could not reflex the whole year-water quality of a watershed, the gene expression profile via RNA-seq provided an alternative way for assessing integrated biotoxicity of surface water, and it was relatively fit for early-warning of water quality of a watershed with unobservable acute toxicity. However, the identification of detail toxicants and the links between DEGs and pollution level as well as physiological-biochemical toxicity needed further investigation.

Vaccine-induced antibody level as the parameter of the influence of environmental salinity on vaccine efficacy in Nile tilapia

To effectively increase production and improve economic returns, the co-culture of Nile tilapia (Oreochromis niloticus) and marine shrimp has been adopted in many countries, including China. Although O. niloticus is an euryhaline fish that can tolerate elevated salinities and even full-strength seawater, fluctuations in salinity levels can undoubtedly induce stress and affect the immune response of this fish. Therefore, this study assessed the impact of salinity on vaccine efficacy in Nile tilapia, which used serum antibody level as a surrogate marker to detect vaccine efficacy. Nile tilapia were acclimatized to 0, 10, 20, or 30 ppt salinity, and then immunized with a formalin-inactivated Streptococcus agalactiae vaccine. Significantly lower levels of antibody in vaccinated fish were found at 20 and 30 ppt salinity compared to 0 and 10 ppt salinity. White blood cell counts, absolute blood lymphocyte counts, and serum bactericidal activity levels were all significantly lower in vaccinated fish at 20 and 30 ppt salinity. Elevated cortisol levels were detected in all of the fish exposure to salinity. Concentrations of serum electrolytes (Na⁺ and Cl^-) were significantly higher in fish at 30 ppt salinity, as compared to fish at lower salinities. Furthermore, the mRNA transcription levels of three of the immune-related genes analyzed (IgM, IL-1β, and IFN-γ, but not Hsp70) were significantly inhibited in the vaccinated fish at 20 and 30 ppt salinity. A suppressed immune response and decreased vaccine efficacy were also indicated by the lower survival rate of vaccinated fish at 20 ppt salinity when challenged with S. agalactiae. Therefore, salinities ≥20 ppt negatively affected antibody production in Nile tilapia, ultimately affecting vaccine efficacy.

Psychoneuroimmunology and immunopsychiatry of zebrafish

Despite the high prevalence of neural and immune disorders, their etiology and molecular mechanisms remain poorly understood. As the zebrafish (Danio rerio) is increasingly utilized as a powerful model organism in biomedical research, mounting evidence suggests these fish as a useful tool to study neural and immune mechanisms and their interplay. Here, we discuss zebrafish neuro-immune mechanisms and their pharmacological and genetic modulation, the effect of stress on cytokines, as well as relevant models of microbiota-brain interplay. As many human brain diseases are based on complex interplay between the neural and the immune system, here we discuss zebrafish models, as well as recent successes and challenges, in this rapidly expanding field. We particularly emphasize the growing utility of zebrafish models in translational immunopsychiatry research, as they improve our understanding of pathogenetic neuro-immune interactions, thereby fostering future discovery of potential therapeutic agents.