Psychoneuroimmunology and immunopsychiatry of zebrafish

Chronic stress-induced immune dysregulation in breast cancer: Implications of psychosocial factors

Chronic stress refers to continuous emotional changes and psychological pressure that individuals experience when they are unable to adjust and stabilize the internal environment over an extended period. It can increase the pressure on endocrine mediators and cytokines in the circulation, as well as tissues throughout the hypothalamic-pituitary-adrenaline (HPA) axis and sympathetic nervous system (SNS); thus, evolving the internal environment of the tumor. This review assesses several key issues, involving psychosocial factors, and integrates clinical, cellular, and molecular studies-as well as the latest research progress-to provide a mechanistic understanding regarding breast oncopsychology. We propose that chronic stress contributes to large individual diferences in the prognosis of breast cancer survivors because they change the basic physiological processes of the endocrine and immune systems, which in turn regulate tumor growth. The study of psychological and physiological reactions of breast cancer patients suggests a new idea for psychological intervention and clinical treatment for breast cancer patients.

Inversely Regulated Inflammation-Related Processes Mediate Anxiety-Obesity Links in Zebrafish Larvae and Adults

Anxiety and metabolic impairments are often inter-related, but the underlying mechanisms are unknown. To seek RNAs involved in the anxiety disorder-metabolic disorder link, we subjected zebrafish larvae to caffeine-induced anxiety or high-fat diet (HFD)-induced obesity followed by RNA sequencing and analyses. Notably, differentially expressed (DE) transcripts in these larval models and an adult zebrafish caffeine-induced anxiety model, as well as the transcript profiles of inherently anxious versus less anxious zebrafish strains and high-fat diet-fed versus standard diet-fed adult zebrafish, revealed inversely regulated DE transcripts. In both larval anxiety and obesity models, these included long noncoding RNAs and transfer RNA fragments, with the overrepresented immune system and inflammation pathways, e.g., the "interleukin signaling pathway" and "inflammation mediated by chemokine and cytokine signaling pathway". In adulthood, overrepresented immune system processes included "T cell activation", "leukocyte cell-cell adhesion", and "antigen processing and presentation". Furthermore, unlike adult zebrafish, obesity in larvae was not accompanied by anxiety-like behavior. Together, these results may reflect an antagonistic pleiotropic phenomenon involving a re-adjusted modulation of the anxiety-metabolic links with an occurrence of the acquired immune system. Furthermore, the HFD potential to normalize anxiety-upregulated immune-related genes may reflect the high-fat diet protection of anxiety and neurodegeneration reported by others.

Capillary Blood Recovery Variables in Young Swimmers: An Observational Case Study

Sport diagnostics is still in pursuit of the optimal combination of biochemical and hematological markers to assess training loads and the effectiveness of recovery. The biochemical and hematological markers selected for a panel should be specific to the sport and training program. Therefore, the aim of this study was to evaluate the usefulness of selected biochemical and hematological variables in professional long-distance and sprint swimming. Twenty-seven participants aged 15–18 years took part in the study. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) activities and creatinine (Cr), C-reactive protein (CRP), ferritin, total bilirubin (TB), direct bilirubin (DB) and iron concentrations were measured for 10 weeks and compared with the traditional sport diagnostic markers of creatine kinase (CK) activity and urea (U) concentration. Additionally, capillary blood morphology was analyzed. An effective panel should consist of measurements of CK and AST activities and urea, TB, DB and ferritin concentrations. These markers provide a good overview of athletes’ post-training effort changes, can help assess the effectiveness of their recovery regardless of sex or competitive distance and are affordable. Moreover, changes in ferritin concentration can indicate inflammation status and, when combined with iron concentration and blood morphology, can help to avoid iron deficiencies, anemia and adverse inflammatory states in swimmers.

Sex differences shape zebrafish performance in a battery of anxiety tests and in response to acute scopolamine treatment

Sex differences influence human and animal behavioral and pharmacological responses. The zebrafish (Danio rerio) is a powerful, popular model system in neuroscience and drug screening. However, the impact of zebrafish sex differences on their behavior and drug responses remains poorly understood. Here, we evaluate baseline anxiety-like behavior in adult male and female zebrafish, and its changes following an acute 30-min exposure to 800-μM scopolamine, a common psychoactive anticholinergic drug. Overall, we report high baseline anxiety-like behavior and more individual variability in locomotion in female zebrafish, as well as distinct, sex-specific (anxiolytic-like in females and anxiogenic-like in males) effects of scopolamine. Collectively, these findings reinforce the growing importance of zebrafish models for studying how both individual and sex differences shape behavioral and pharmacological responses.

Acute and chronic stress differently alter the expression of cytokine and neuronal markers genes in zebrafish brain

We report the effects of acute and chronic stress on the expression of selective immune-related genes and markers of neuronal function in the brain of the zebrafish (Danio rerio). Fish were distributed into three groups: the non-stressed control group; the acute stress (AS) group, submitted to a single stressing episode; and the unpredictable chronic stress (UCS) group, submitted to two daily stressing episodes of alternating times and types of stress. The stressing protocols were applied for a period of 14 days. The UCS protocol triggered the expression of the pro-inflammatory cytokine genes IL-1β and TNF-α, the anti-inflammatory cytokine IL-10 (negative feedback from the immune system), reduction in cFOS gene expression, and caused neuro-inflammation. The AS protocol had no effect on gene expression. Altered expression of cytokine genes, as observed in our study, correlates with several pathologies associated with neuro-inflammation, and the reduction of cFOS gene expression may indicate the occurrence of reduced neuronal plasticity. Our study further extends our knowledge about the interaction of the immune system and the different forms of stress.

Differential Th Cell-Related Immune Responses in Young Physically Active Men after an Endurance Effort

The participation of T cell subsets in the modulation of immunity in athletes triggered by maximal effort was investigated. In total, 80 physically active young men (range 16-20 years) were divided into 5 age groups: 16, 17, 18, 19, and 20 years old. They performed efficiency tests on mechanical treadmills until exhaustion. White blood cell (WBC) and lymphocyte (LYM) counts were determined, and the type 1 (Th1), type 2 (Th2) helper T cells, T helper 17 (Th17), and T regulatory (Treg) cell distribution and plasma levels of selected cytokines were analyzed. An increase in WBC and LYM counts after the test and in Th1 and Treg cells after the test and in recovery was observed. There were no changes in Th2 cells. An increase in interleukins (IL): IL-2 and IL-8 was observed. The IL-6 level was altered in all studied groups. IL-17A and interferon gamma (IFN-γ) levels were increased in all studied groups. The mechanism of differential T cell subset activation may be related to athletes' age. The novel findings of this study are the involvement of Th17 cells in post-effort immune responses and the participation of IL-6 in post-effort and the long-term biological effect of endurance effort.

Acute embryonic exposure of zebrafish to permethrin induces behavioral changes related to anxiety and aggressiveness in adulthood

Permethrin (PM) is one of the most used synthetic pyrethroid worldwide. Exposure to this compound during pregnancy and early childhood has been indicated as a risk factor for neurodevelopmental disorders. We evaluated the long-term effects of embryonic PM exposure in different stages of zebrafish development. Briefly, embryos (3 hpf) were exposed to sub-lethal concentrations of PM (25 and 50 μg.L^-1) during 24 h and then behavioral parameters were evaluated during embryonic (28 hpf), eleutheroembryonic (3 dpf), larval (7 dpf), and adult stages (90 dpf). PM exposure decreased spontaneous movement at 28 hpf and decreased thigmotaxis in eleutheroembryos. The long-term effects of PM include changes in non-motor behaviors such as fear and anxiety in larva and adults. Adults embryonically exposed to PM also showed a significant increase in aggressiveness parameters. These results demonstrated that embryonic exposure to PM induces persistent neurotoxic effects in adulthood, which can impair the cognitive and behavioral fitness of non-target species contributing to a rise in neurodevelopmental disorders.

T helper cell-related changes in peripheral blood induced by progressive effort among soccer players

Objectives

The regulatory mechanisms affecting the modulation of the immune system accompanying the progressive effort to exhaustion, particularly associated with T cells, are not fully understood. We analysed the impact of two progressive effort protocols on T helper (Th) cell distribution and selected cytokines.

Methods

Sixty-two male soccer players with a median age of 17 (16–29) years performed different protocols for progressive exercise until exhaustion: YO-YO (YYRL1) and Beep. Blood samples for all analyses were taken three times: at baseline, post-effort, and in recovery.

Results

The percentage of Th1 cells increased post-effort and in recovery. The post-effort percentage of Th1 cells was higher in the Beep group compared to the YYRL1 group. Significant post-effort increase in Th17 cells was observed in both groups. The post-effort percentage of regulatory T cells (Treg) increased in the Beep group. An increased post-effort concentration of IL-2, IL-6, IL-8 and IFN-γ in both groups was observed. Post-effort TNF-α and IL-10 levels were higher than baseline in the YYRL1 group, while the post-effort IL-17A concentration was lower than baseline only in the Beep group. The recovery IL-2, IL-4, TNF-α and IFN-γ levels were higher than baseline in the YYRL1 group. The recovery IL-4, IL-6, IL-8, TNF-α and IFN-γ values were higher than baseline in the Beep group.

Conclusion

The molecular patterns related to cytokine secretion are not the same between different protocols for progressive effort. It seems that Treg cells are probably the key cells responsible for silencing the inflammation and enhancing anti-inflammatory pathways.

Infection and RNA-seq analysis of a zebrafish tlr2 mutant shows a broad function of this toll-like receptor in transcriptional and metabolic control and defense to Mycobacterium marinum infection

Background

The function of Toll-like receptor 2 (TLR2) in host defense against pathogens, especially Mycobacterium tuberculosis (Mtb) is poorly understood. To investigate the role of TLR2 during mycobacterial infection, we analyzed the response of tlr2 zebrafish mutant larvae to infection with Mycobacterium marinum (Mm), a close relative to Mtb, as a model for tuberculosis. We measured infection phenotypes and transcriptome responses using RNA deep sequencing in mutant and control larvae.

Results

tlr2 mutant embryos at 2 dpf do not show differences in numbers of macrophages and neutrophils compared to control embryos. However, we found substantial changes in gene expression in these mutants, particularly in metabolic pathways, when compared with the heterozygote tlr2^+/− control. At 4 days after Mm infection, the total bacterial burden and the presence of extracellular bacteria were higher in tlr2^−/− larvae than in tlr2^+/−, or tlr2^+/+ larvae, whereas granuloma numbers were reduced, showing a function of Tlr2 in zebrafish host defense. RNAseq analysis of infected tlr2^−/− versus tlr2^+/− shows that the number of up-regulated and down-regulated genes in response to infection was greatly diminished in tlr2 mutants by at least 2 fold and 10 fold, respectively. Analysis of the transcriptome data and qPCR validation shows that Mm infection of tlr2 mutants leads to decreased mRNA levels of genes involved in inflammation and immune responses, including il1b, tnfb, cxcl11aa/ac, fosl1a, and cebpb. Furthermore, RNAseq analyses revealed that the expression of genes for Maf family transcription factors, vitamin D receptors, and Dicps proteins is altered in tlr2 mutants with or without infection. In addition, the data indicate a function of Tlr2 in the control of induction of cytokines and chemokines, such as the CXCR3-CXCL11 signaling axis.

Conclusion

The transcriptome and infection burden analyses show a function of Tlr2 as a protective factor against mycobacteria. Transcriptome analysis revealed tlr2-specific pathways involved in Mm infection, which are related to responses to Mtb infection in human macrophages. Considering its dominant function in control of transcriptional processes that govern defense responses and metabolism, the TLR2 protein can be expected to be also of importance for other infectious diseases and interactions with the microbiome.

IFN-γ inhibits 5-HT-induced melanin biosynthesis via downregulation of 5-HT receptors in vivo/in vitro

Hypopigmentation disorders, such as vitiligo, are difficult for treatment due to complicated pathogenesis, resulting from multiple factors including neural and immune elements. 5-HT and IFN-γ both play crucial roles in these skin diseases. However, the interactions between 5-HT and IFN-γ in regulation of melanogenesis is still unknown. Our study aimed at exploring whether IFN-γ affects 5-HT-induced melanogenesis and searching the mechanism. In our study, IFN-γ attenuated 5-HT-induced pigmentation and green fluorescent protein (GFP) expression in zebrafishes. In addition, we found that IFN-γ decreased serum serotonin levels as well as the cutaneous expression of tryptophan hydroxylase 1 (TPH1), 5-HT1A receptor (5-HT1AR) and 5-HT1B receptor (5-HT1BR) in C57BL/6 mice. Moreover, IFN-γ attenuated 5-HT-induced melanin biosynthesis as well as the expression of 5-HT1AR, 5-HT1BR and 5-HT2A receptor (5-HT2AR) in B16F10 cells, which blocked by interferon-γ receptor 1 and interferon-γ receptor 2 (IFNGR1/IFNGR2) antibodies. In summary, IFN-γ not only affects melanogenesis alone, but also inhibits 5-HT response on melanin biosynthesis. Mediated by IFNGR1/IFNGR2, IFN-γ downregulated 5-HT receptors expression, which directly affect 5-HT-induced melanin biosynthesis. Our work may give insights into the drug development of hypopigmentation disorders with neuro-immune derangement.

Zebrafish models of diabetes-related CNS pathogenesis

Diabetes mellitus (DM) is a common metabolic disorder that affects multiple organ systems. DM also affects brain processes, contributing to various CNS disorders, including depression, anxiety and Alzheimer's disease. Despite active research in humans, rodent models and in-vitro systems, the pathogenetic link between DM and brain disorders remains poorly understood. Novel translational models and new model organisms are therefore essential to more fully study the impact of DM on CNS. The zebrafish (Danio rerio) is a powerful novel model species to study metabolic and CNS disorders. Here, we discuss how DM alters brain functions and behavior in zebrafish, and summarize their translational relevance to studying DM-related CNS pathogenesis in humans. We recognize the growing utility of zebrafish models in translational DM research, as they continue to improve our understanding of different brain pathologies associated with DM, and may foster the discovery of drugs that prevent or treat these diseases.

Resident Immunity in Tissue Repair and Maintenance: The Zebrafish Model Coming of Age

The zebrafish has emerged as an exciting vertebrate model to study different aspects of immune system development, particularly due to its transparent embryonic development, the availability of multiple fluorescent reporter lines, efficient genetic tools and live imaging capabilities. However, the study of immunity in zebrafish has largely been limited to early larval stages due to an incomplete knowledge of the full repertoire of immune cells and their specific markers, in particular, a lack of cell surface antibodies to detect and isolate such cells in living tissues. Here we focus on tissue resident or associated immunity beyond development, in the adult zebrafish. It is our view that, with our increasing knowledge and the development of improved tools and protocols, the adult zebrafish will be increasingly appreciated for offering valuable insights into the role of immunity in tissue repair and maintenance, in both health and disease throughout the lifecourse.