Interleukin-2 family cytokines: An overview of genes, expression, signaling and functional roles in teleost

The role of interleukin (IL)-2 cytokine family in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder, which primarily impacts the nervous system, marked by its immune and inflammatory characteristics. The interleukin-2 (IL-2) cytokine family has a crucial role in regulating both neuroinflammation and immune activity, positioning it as one of the critical immune pathways in PD. Balancing pro-inflammatory and anti-inflammatory signals in PD heavily depends on the IL-2 cytokine family, that includes IL-2, IL-4, IL-7, IL-9, IL-15 and IL-21. This balance is vital for neuron survival and resistance to degeneration. Disruptions in IL-2 signaling can upset the equilibrium among regulatory T cells (Tregs) and pro-inflammatory T cells, such as Th1 and Th17, further aggravating the chronic neuroinflammation typical of PD. In PD, a decline in IL-2 or receptor dysfunction can hinder Treg activity, leading to increased inflammation and neurodegeneration. Similarly, IL-15 and IL-21 supports cytotoxic immune cell function, including natural killer (NK) cells and CD8+ T cells, which may exacerbate neuronal damage by sustaining pro-inflammatory processes. Moreover, IL-4 and IL-7 have anti-inflammatory roles in maintaining T cell homeostasis, and their dysregulation can contribute to interruption of the blood-brain barrier and increased infiltration of immune cells into the central nervous system. Targeting the IL-2 cytokine family in Parkinson's disease has shown therapeutic potential by expanding Tregs, which reduce neuroinflammation and promote dopaminergic neuron survival. Recombinant IL-2 and IL-2/anti-IL-2 complexes have demonstrated efficacy in animal models, enhancing Treg function and leading to improved neuroprotection. Additionally, IL-4-based therapies have been explored for their ability to shift microglia toward a neuroprotective phenotype, further enhancing neuronal survival by modulating inflammatory responses and cellular metabolism. Current research is exploring how to optimize cytokine delivery while minimizing immune side effects, with the goal of developing more targeted therapies for PD.

Comparative analysis of immunogenicity for viral hemorrhagic septicemia virus (VHSV) vaccines inactivated by different methods

Viral hemorrhagic septicemia virus (VHSV) belonging to the genus Novirhabdovirus and family Rhabdoviridae is a major viral disease that causes economic loss in the olive flounder (Paralichthys olivaceus). In this study, we produced formalin-, binary ethylenimine (BEI)-, β-propiolactone (BPL)-, and heat-treated, inactivated VHSV vaccines; and observed the glycoprotein changes in the inactivated VHSV vaccines and confirmed their correlation with vaccine efficacy. The control group showed a 100 % cumulative mortality rate, but the groups immunized with formalin- and BPL-inactivated VHSV vaccines had high survival rates of 80 % and 90 %, and the virus copy numbers was significantly low. Conversely, groups immunized with BEI- and heat-inactivated VHSV vaccines had low survival rates of 20 % and 30 %, and high virus copy numbers. Fish immunized with formalin- and BPL-inactivated VHSV vaccines significantly increased VHSV-specific immunoglobulin (Ig) M titers in serum, and showed significant upregulation of several immune genes (Mx, ISG15, IL-10, IFNγ, and CD8α) in the spleen. Upon VHSV challenge, the BPL group displayed significant upregulation of IL-2, CD8α, and IgM along with downregulation of Mx, IL-10, IL-17A, and IFNγ compared to the virus infected control group. When evaluating the antigenic change of VHSV glycoprotein (G) protein using 4 different VHSV G monoclonal antibodies, formalin- and BPL-inactivated VHSV conserved VHSV monomer G similar to the non-inactivated VHSV, whereas BEI- and heat-inactivated VHSV monomer G exhibited changes. These results suggest that the conserved disulfide bond-dependent G protein structure of the inactivated VHSV may induce significant immune responses in fish, resulting in high protective efficacy.

Characteristics and functions of interleukin 21 in channel catfish (Ictalurus punctatus)

Interleukin-21 (IL-21) is mainly produced by CD4+ T cells and NKT cells, belonging to the gamma chain (γc) family. It promotes the proliferation, activation, and differentiation of immune cells and activates the JAK-STAT, MAPK signaling, and PI3K pathways to regulate immune responses, crucially impacting anti-infectious inflammatory responses. In this study, IL-21 was successfully identified in channel catfish (Ictalurus punctatus, Ip), with a coding sequence (CDS) length of 438 bp encoding a 145-amino acid (aa) protein. The signal peptide comprised 19 aa, while the mature peptide consists of 126 aa, featuring four α-helix structures and two pairs of disulfide bonds from four conserved cysteine residues. qPCR data revealed highest IpIL-21 expression in channel catfish gills and spleen. Bacterial and viral infections upregulated IpIL-21 expression across multiple tissues. Poly(I:C) specifically enhanced IpIL-21 expression in channel catfish kidney cells (CCK) at 48 h post-infection (hpi). In vitro, recombinant IpIL-21 (rIpIL-21) protein induced upregulation of IL-10, IL-21, IL-1β, and STAT3 expression in CCK, while inhibiting IL-22 and IL-26 expression. IL-6 and IL-20 expressions were inhibited at low doses and induced at high doses, demonstrating a dose-dependent pattern. These findings underscored IpIL-21's significance as a critical immune factor in channel catfish, pivotal for the antibacterial inflammatory response defense system.

The Dual-Edged Sword: Risks and Benefits of JAK Inhibitors in Infections

Janus kinase inhibitors (JAKis) represent a relatively new class of immunomodulatory drugs with potent effects on various cytokine signalling pathways. They have revolutionized the treatment landscape for autoimmune diseases such as rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis. However, their ability to modulate immune responses presents a dual-edged nature, influencing both protective immunity and pathological inflammation. This review explores the complex role of JAKis in infectious settings, highlighting both beneficial and detrimental effects. On the one hand, experimental models suggest that JAK inhibition can impair host defence mechanisms, increasing susceptibility to certain bacterial and viral infections. For example, tofacitinib-treated mice exhibited more severe joint erosions in Staphylococcus aureus (S. aureus) septic arthritis and showed impaired viral clearance in herpes simplex encephalitis. Additionally, clinical data confirm an increased risk of herpes zoster in patients receiving JAKis, underscoring the need for rigorous monitoring. On the other hand, JAK inhibition has demonstrated protective effects in certain infectious and hyperinflammatory conditions. In sepsis models, including cecal ligation and puncture (CLP) and S. aureus bacteraemia, tofacitinib improved survival by attenuating excessive inflammation. Furthermore, JAKis, particularly baricitinib, have shown substantial efficacy in mitigating cytokine storms during severe COVID-19 infections, leading to improved clinical outcomes and reduced mortality. These observations suggest that JAKis have a role in modulating hyperinflammatory responses in select infectious contexts. In conclusion, JAKis present a complex interplay between immunosuppression and immunomodulation. While they increase the risk of certain infections, they also show potential in managing hyperinflammatory conditions such as cytokine storms. The key challenge is determining which patients and situations benefit most from JAKis while minimizing risks, requiring a careful and personalized treatment approach.

The Lasting Impact of IL-2: Approaching 50 Years of Advancing Immune Tolerance, Cancer Immunotherapies, and Autoimmune Diseases

BACKGROUND

The discovery of interleukin-2 (IL-2) and its receptor (IL-2R) almost 50 years ago revolutionized immunology, marking a pivotal moment in understanding T cell biology and immune regulation. Initially identified as a T cell growth factor, IL-2 unveiled critical insights into cytokine-mediated immune cell proliferation and differentiation.

METHODS

This review highlighted the characterization of IL-2R as a multi-chain receptor complex set a precedent for decoding cytokine receptor signaling. The unique interplay between IL-2 and its high-affinity receptor component, IL-2Rα, epitomizes the principle of specificity and efficiency in cytokine signaling, enabling precise immune modulation. Regulatory T cells (Tregs) exploit IL-2Rα high affinity to outcompete effector T cells for IL-2, ensuring immune tolerance and preventing autoimmunity.

RESULTS

Despite its foundational role in immune homeostasis, leveraging IL-2 for therapeutic purposes has proven challenging.

CONCLUSION

IL-2-based therapies hold transformative potential in autoimmunity, cancer immunology, and transplantation, yet they remain elusive due to the complex balance between immunostimulatory and immunosuppressive effects. This review explores the milestones in IL-2 biology, its dualistic functions, and the ongoing quest to harness its therapeutic promise.

Contribution of interleukins in the regulation of teleost fish immunity: A review from the perspective of regulating macrophages

Interleukins (ILs) are potent secreted regulators of a wide range of cell types and cellular activities, particularly in the immune system. They are able to participate in intercellular communication in homeostasis and disease, thereby exerting immune functions. Macrophages serve as the innate immune cells of vertebrates and play a pivotal role in defending against and eliminating external pathogens. In mammals, the immune response mounted by macrophages is intricately linked to ILs. Given the fact that teleost fish have evolved an innate immune system that closely resembles those of mammals, particularly in terms of the functionality of macrophages, raises the intriguing possibility that the regulatory function of ILs in macrophage-mediated immunity might be evolutionarily conserved across both mammal and teleost fish lineages. Consequently, from the perspective of interleukin regulation of macrophages, this review outlines the relationship between ILs and macrophages in teleost fish, and elucidates the regulatory role of ILs of immune cell function in teleost fish, thereby contributing to our understanding of the key role of these cytokines in the prevention and control of aquaculture diseases.

Human immune system: Exploring diversity across individuals and populations

The immune response is an intricate system that involves the complex connection of cellular and molecular components, each with distinct functional specialisations. It has a distinct capacity to adjust and mould the immune response in accordance with specific stimuli, influenced by both genetic and environmental factors. The presence of genetic diversity, particularly across different ethnic and racial groups, significantly contributes to the impact of incidence of diseases, disease susceptibility, autoimmune disorders, and cancer risks in specific regions and certain populations. Environmental factors, including geography and socioeconomic status, further modulate the variety of the immune system responses. These, in turn, affect the susceptibility to infectious diseases and development of autoimmune disorders. Despite the complexity of the relationship, there remains a gap in understanding the specificity of immune indices across races, immune reference ranges among populations, highlighting the need for deeper understanding of immune diversity for personalized approaches in diagnostics and therapeutics. This review systematically organizes these findings, with the goal of emphasizing the potential of targeted interventions to address health disparities and advance translational research, enabling a more comprehensive strategy. This approach promises significant advancements in identifying specific immunological conditions, focusing on personalized interventions, through both genetic and environmental factors.

The Potential of Glucosinolates and Their Hydrolysis Products as Inhibitors of Cytokine Storms

A cytokine storm is an intense inflammatory response characterized by the overproduction of proinflammatory cytokines, resulting in tissue damage, and organ dysfunction. Cytokines play a crucial role in various conditions, such as coronavirus disease, in which the immune system becomes overactive and releases excessive levels of cytokines, including interleukins, tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ). This anomalous response often leads to acute respiratory distress syndrome (ARDS), disseminated intravascular coagulation (DIC), and multiple organ injury (MOI). Glucosinolates are plant secondary metabolites predominantly found in Brassica vegetables, but are also present in other species, such as Moringa Adens and Carica papaya L. When catalyzed by the enzyme myrosinase, glucosinolates produce valuable products, including sulforaphane, phenethyl isothiocyanate, 6-(methylsulfinyl) hexyl isothiocyanate, erucin, goitrin, and moringin. These hydrolyzed products regulate proinflammatory cytokine production by inhibiting the nuclear factor kappa-light-chain-enhancer of activated B-cell (NF-κB) signaling pathway and stimulating the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. This action can alleviate hyperinflammation in infected cells and modulate cytokine storms. In this review, we aimed to examine the potential role of glucosinolates in modulating cytokine storms and reducing inflammation in various conditions, such as coronavirus disease. Overall, we found that glucosinolates and their hydrolysis products can potentially attenuate cytokine production and the onset of cytokine storms in diseased cells. In summary, glucosinolates could be beneficial in regulating cytokine production and preventing complications related to cytokine storms.

Cytotoxic and Immunomodulatory Effects of Hypericin as a Photosensitizer in Photodynamic Therapy Used on Skin Cell Cultures

Determination of the hypericin-photodynamic (HY-PDT) effect on the secretion of cytokines secreted by the skin cells, may be the basis for using the immunomodulatory effect of photodynamic action in the treatment of inflammatory skin diseases. The study aimed to evaluate the cytotoxic and immunomodulatory effects of hypericin (HY) in photodynamic therapy (PDT) performed in vitro on cultures of selected skin cell lines. The study used two human cell lines, primary dermal fibroblast (HDFa) and primary epidermal keratinocytes (HEKa). The MTT test was used to define the metabolic activity of treated cells. Cell supernatants subjected to sublethal PDT were assessed to determine the interleukins: IL-2, IL-8, IL-10, IL-11, IL-19, IL-22, and metalloproteinase 1 (MMP-1). The results confirm the destructive effect of HY-PDT and the immunomodulatory effects of sublethal doses on the selected skin cells, depending on the concentration of HY and the light doses. No statistically significant differences were noted in IL-2 and IL-10 concentration after HY-PDT for HEKa and HDFa lines. After using HY-PDT, the concentration of IL-8, MMP-1, IL-22, and IL-11 significantly decreased in the HEKa line. Moreover, the concentration of IL-19 and MMP-1 significantly decreased in the HDFa line. The concentration of IL-11 in the HDFa line after using only the HY, without the light, increased but decreased after HY-PDT. Our experiment confirmed that HY-PDT has not only a cytotoxic effect but, used in sublethal doses, also presents immunomodulatory properties. These may be an advantage of HY-PDT when used in the treatment of persistent skin inflammation, connected with the release of pro-inflammatory cytokines resistant to conventional treatment methods.

Inducible IL-2 production and IL-2+ cell expansion are landmark events for T-cell activation of teleost

As a multipotent cytokine, interleukin (IL)-2 plays important roles in activation, differentiation and survival of the lymphocytes. Although biological characteristics and function of IL-2 have been clarified in several teleost species, evidence regarding IL-2 production at the cellular and protein levels is still scarce in fish due to the lack of reliable antibody. In this study, we developed a mouse anti-Nile tilapia IL-2 monoclonal antibody (mAb), which could specifically recognize IL-2 protein and identify IL-2-producing lymphocytes of tilapia. Using this mAb, we found that CD3+ T cells, but not CD3- lymphocytes, are the main cellular source of IL-2 in tilapia. Under resting condition, both CD3+CD4-1+ T cells and CD3+CD4-1- T cells of tilapia produce IL-2. Moreover, the IL-2 protein level and the frequency of IL-2+ T cells significantly increased once T cells were activated by phytohemagglutinin (PHA) or CD3 plus CD28 mAbs in vitro. In addition, Edwardsiella piscicida infection also induces the IL-2 production and the expansion of IL-2+ T cells in the spleen lymphocytes. These findings demonstrate that IL-2 takes part in the T-cell activation and anti-bacterial adaptive immune response of tilapia, and can serve as an important marker for T-cell activation of teleost fish. Our study has enriched the knowledge regarding T-cell response in fish species, and also provide novel perspective for understanding the evolution of adaptive immune system.

Unveiling the potential effects of resveratrol in lung cancer treatment: Mechanisms and nanoparticle-based drug delivery strategies

Lung cancer ranks among the most prevalent forms of cancer and remains a significant factor in cancer-related mortality across the world. It poses significant challenges to healthcare systems and society as a whole due to its high incidence, mortality rates, and late-stage diagnosis. Resveratrol (RV), a natural compound found in various plants, has shown potential as a nanomedicine for lung cancer treatment. RV has varied effects on cancer cells, including promoting apoptosis by increasing pro-apoptotic proteins (Bax and Bak) and decreasing anti-apoptotic proteins (Bcl-2). It also hinders cell proliferation by influencing important signaling pathways (MAPK, mTOR, PI3K/Akt, and Wnt/β-catenin) that govern cancer progression. In addition, RV acts as a potent antioxidant, diminishing oxidative stress and safeguarding cells against DNA damage. However, using RV alone in cancer treatment has drawbacks, such as low bioavailability, lack of targeting ability, and susceptibility to degradation. In contrast, nanoparticle-based delivery systems address these limitations and hold promise for improving treatment outcomes in lung cancer; nanoparticle formulations of RV offer advantages such as improved drug delivery, increased stability, controlled release, and targeted delivery to lung cancer cells. This article will provide an overview of lung cancer, explore the potential of RV as a therapeutic agent, discuss the benefits and challenges of nanoparticle-based drug delivery, and highlight the promise of RV nanoparticles for cancer treatment, including lung cancer. By optimizing these systems for clinical application, future studies aim to enhance overall treatment outcomes and improve the prognosis for lung cancer patients.

Exploring the impact of nano-Se and nano-clay feed supplements on interleukin genes, immunity and growth rate in European Sea Bass (Dicentrarchus labrax)

This study aimed to investigate the effects of adding Nano-Selenium (NSe) and Nano-clay (NC) as feed supplements on European Sea Bass (Dicentrarchus labrax). Two separate experiments were conducted, one with NC and the other with NSe. Each experiment consisted of four sub-groups with varying concentrations of NC or NSe. The expression levels of five immune-related genes (TNF-α, TNF-β, IL-2, IL-6 and IL-12) were measured using Real-time Quantitative PCR (Rt-PCR) Assay. The results showed an increase in the expression of interleukins (IL-2, IL-6 and IL-12) and pro-inflammatory cytokines (TNF-α and TNF-β) after exposure to NC and NSe. TNF-α gene expression was significantly higher with both 1 mg and 10 mg concentrations of NC and NSe. TNF-β gene expression was highest with the 5 mg concentration of NC. The concentrations of 1 mg and 10 mg for NC, and 1 mg, 5 mg, and 10 mg for NSe, led to the highest (p < 0.05) levels of IL-2 expression compared to the control. Similar trends were observed for IL-6 and IL-12 gene expression. Understanding the impact of these concentrations on gene expression, growth rate, biochemical indices, and antioxidant status can provide valuable insights into the potential applications of NC and NSe supplements on European Sea Bass.

Pain and the biochemistry of fibromyalgia: patterns of peripheral cytokines and chemokines contribute to the differentiation between fibromyalgia and controls and are associated with pain, fat infiltration and content

Objectives

This explorative study analyses interrelationships between peripheral compounds in saliva, plasma, and muscles together with body composition variables in healthy subjects and in fibromyalgia patients (FM). There is a need to better understand the extent cytokines and chemokines are associated with body composition and which cytokines and chemokines differentiate FM from healthy controls.

Methods

Here, 32 female FM patients and 30 age-matched female healthy controls underwent a clinical examination that included blood sample, saliva samples, and pain threshold tests. In addition, the subjects completed a health questionnaire. From these blood and saliva samples, a panel of 68 mainly cytokines and chemokines were determined. Microdialysis of trapezius and erector spinae muscles, phosphorus-31 magnetic resonance spectroscopy of erector spinae muscle, and whole-body magnetic resonance imaging for determination of body composition (BC)-i.e., muscle volume, fat content and infiltration-were also performed.

Results

After standardizing BC measurements to remove the confounding effect of Body Mass Index, fat infiltration and content are generally increased, and fat-free muscle volume is decreased in FM. Mainly saliva proteins differentiated FM from controls. When including all investigated compounds and BC variables, fat infiltration and content variables were most important, followed by muscle compounds and cytokines and chemokines from saliva and plasma. Various plasma proteins correlated positively with pain intensity in FM and negatively with pain thresholds in all subjects taken together. A mix of increased plasma cytokines and chemokines correlated with an index covering fat infiltration and content in different tissues. When muscle compounds were included in the analysis, several of these were identified as the most important regressors, although many plasma and saliva proteins remained significant.

Discussion

Peripheral factors were important for group differentiation between FM and controls. In saliva (but not plasma), cytokines and chemokines were significantly associated with group membership as saliva compounds were increased in FM. The importance of peripheral factors for group differentiation increased when muscle compounds and body composition variables were also included. Plasma proteins were important for pain intensity and sensitivity. Cytokines and chemokines mainly from plasma were also significantly and positively associated with a fat infiltration and content index.

Conclusion

Our findings of associations between cytokines and chemokines and fat infiltration and content in different tissues confirm that inflammation and immune factors are secreted from adipose tissue. FM is clearly characterized by complex interactions between peripheral tissues and the peripheral and central nervous systems, including nociceptive, immune, and neuroendocrine processes.

Effects of dietary Nisin on growth performance, immune function, and gut health of broilers challenged by Clostridium perfringens

Nisin (Ni) is a polypeptide bacteriocin produced by lactic streptococci (probiotics) that can inhibit the majority of gram-positive bacteria, and improve the growth performance of broilers, and exert antioxidative and anti-inflammatory properties. The present study investigated the potential preventive effect of Nisin on necrotic enteritis induced by Clostridium perfringens (Cp) challenge. A total of 288 Arbor Acres broiler chickens of 1-d-olds were allocated using 2 × 2 factorial arrangement into four groups with six replicates (12 chickens per replicate), including: (1) control group (Con, basal diet), (2) Cp challenge group (Cp, basal diet + 1.0 × 108 CFU/mL Cp), (3) Ni group (Ni, basal diet + 100 mg/kg Ni), and (4) Ni + Cp group (Ni + Cp, basal diet + 100 mg/kg Ni + 1.0 × 108 CFU/mL Cp). The results showed that Cp challenge decreased the average daily gain (ADG) of days 15 to 21 (P<0.05) and increased interleukin-6 (IL-6) content in the serum (P < 0.05), as well as a significant reduction in villus height (VH) and the ratio of VH to crypt depth (VCR) (P<0.05) and a significant increase in crypt depth (CD) of jejunum (P<0.05). Furthermore, the mRNA expressions of Occludin and Claudin-1 were downregulated (P<0.05), while the mRNA expressions of Caspase3, Caspase9, Bax, and Bax/Bcl-2 were upregulated (P<0.05) in the jejunum. However, the inclusion of dietary Ni supplementation significantly improved body weight (BW) on days 21 and 28, ADG of days 15 to 21 (P<0.05), decreased CD in the jejunum, and reduced tumor necrosis factor-α (TNF-α) content in the serum (P<0.05). Ni addition upregulated the mRNA levels of Claudin-1 expression and downregulated the mRNA expression levels of Caspase9 in the jejunum (P<0.05). Moreover, Cp challenge and Ni altered the cecal microbiota composition, which manifested that Cp challenge decreased the relative abundance of phylum Fusobacteriota and increased Shannon index (P<0.05) and the trend of phylum Proteobacteria (0.05 Collapse

Key Words

• Clostridium perfringens
• broiler
• gut health
• necrotic enteritis
• nisin

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MESH Headings

• Animals
• Clostridium perfringens
• Chickens
• Intestines
• Clostridium Infections/prevention & control
• Clostridium Infections/veterinary
• Clostridium Infections/microbiology
• Nisin/pharmacology
• Claudin-1
• bcl-2-Associated X Protein/pharmacology
• Diet/veterinary
• RNA, Messenger/genetics
• Immunity
• Poultry Diseases/microbiology
• Dietary Supplements
• Animal Feed/analysis

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Affiliation(s)

Hua Yuan College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China
Guangdong Bai College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China College of Animal Science and Technology, Southwest University, Chongqing 400715, China
Yu Lin College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China
Xilong Yu College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China
Qinghui Yang College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China
Renkai Dou College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China
Hao Sun College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China
Zeyu Zhao College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China
Zhongyu Li College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China
Zhihui Chen College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China
Liangmei Xu College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China

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The Biological Functions and Intestinal Inflammation Regulation of IL-21 in Grass Carp (Ctenopharyngodon idella) during Infection with Aeromonas hydrophila

Interleukin (IL) 21 is a pleiotropic cytokine that plays an important role in regulating innate and adaptive immune responses. In fish, the biological functions and cell source of IL-21 remain largely unknown. In this study, we performed qRT-PCR, Western blotting and immunofluorescent microscopy to examine the expression of IL-21 at the mRNA and protein levels. We found that il21 expression was induced in the primary head kidney leukocytes of grass carp (Ctenopharyngodon idella) by heat-inactivated Aeromonas hydrophila (A. hydrophila) and LPS and in tissues after infection with A. hydrophila. Recombinant IL-21 protein produced in the CHO-S cells was effective in elevating the expression of antibacterial genes, including β-defensin and lysozyme, and, interestingly, inhibited the NF-κB signaling pathway. Furthermore, we investigated the response of the IL-21 expressing cells to A. hydrophila infection. Immunofluorescent assay showed that IL-21 protein was detected in the CD3γ/δ T cells and was markedly accumulated in the anterior, middle and posterior intestine. Collectively, the results indicate that IL-21 plays an important role in regulating the intestinal inflammation induced by bacterial infection in grass carp.

The SEB1741 Aptamer Is an Efficient Tool for Blocking CD4+ T Cell Activation Induced by Staphylococcal Enterotoxin B

Staphylococcal enterotoxin B (SEB) is a protein produced by Staphylococcus aureus, which is toxic to humans. It is well known for its ability to stimulate the exacerbated activation of proinflammatory CD4+ T cells (Th1 profile), and in vitro studies have been conducted to understand its mechanism of action and its potential use as an immune therapy. However, the efficiency of the SEB1741 aptamer in blocking SEB has not been experimentally demonstrated.

METHODS

Enrichment CD4+ T cells were stimulated with SEB, and as a blocker, we used the SEB1741 aptamer, which was previously synthesised by an "in silico" analysis, showing high affinity and specificity to SEB. The efficiency of the SEB1741 aptamer in blocking CD4+ T cell activation was compared with that of an anti-SEB monoclonal antibody. Flow cytometry and Bio-Plex were used to evaluate the T-cell function.

RESULTS

In vitro, SEB induced the activation of CD4+ T cells and favoured a Th1 profile; however, the SEB1741 aptamer was highly efficient in decreasing the frequency of CD4+ T cells positive to ki-67 and CD69 cells, this means that proliferation and activation of CD4+ T cells was decreased. Moreover, the production of interleukin 2 (IL-2) and interferon-gamma (IFN-γ) was affected, suggesting that the Th1 profile is not present when the SEB1441 aptamer is used. Thus, the SEB1741 function was similar to that of anti-SEB.

CONCLUSIONS

The SEB1741 aptamer is a valuable tool for blocking CD4+ T cell activation and the subsequent release of proinflammatory cytokines by SEB stimulation.