CD122 is an activation marker ensuring proper proliferation of T cells in teleost.

As one of subunits for interleukin-2 receptor (IL-2R), CD122 can bind to IL-2 and then activate downstream signal transduction to participate in adaptive immune response. Although CD122 has been identified and investigated from several teleost species, studies on its function at T-cell level are still scarce for lack of specific antibodies. In this study, a typical CD122 in Nile tilapia (Oreochromis niloticus) was characterized by bioinformatics analysis, cloned to produce retrovirus infected NIH/3T3 cells for mouse immunization. After cell fusion and screening, we successfully developed a mouse anti-tilapia CD122 monoclonal antibody (mAb), which could specifically recognize CD122 and identify CD122-producing T cells of tilapia. Using the mAb to detect, CD122 was found to widely distribute in immune-related tissues, and significantly elevate post Edwardsiella piscicida infection or T-cell activation. More importantly, the expansion of CD122+ T cells and up-regulation of CD122 occurred both in total T cells and T-cell subsets during T-cell activation upon in vitro stimulation or in vivo infection. These results indicate that CD122 can be used as a T-cell activation marker in tilapia. Notably, CD122 mAb blocking blunted the activation of MAPK/Erk and mTORC1 pathways, and inhibited T-cell proliferation, suggesting a critical role of CD122 in ensuring proper proliferation of tilapia T cells. Therefore, this study enriches the knowledge of T-cell responses in fish and provides new evidence for understanding the evolution of lymphocyte-mediated adaptive immunity.

Granzyme B secreted by T cells is involved in anti-bacterial immune response of tilapia.

Secreted by natural killer cells and cytotoxic T lymphocytes, Granzyme B is involved in regulating the adaptive immune response in vertebrates and plays a pivotal role in resisting virus invasion and removing pathogens. Although it had been extensively studied in mammals, the involvement of Granzyme B in adaptive immune response of early vertebrates remained elusive. In this study, we investigated the Granzyme B in Oreochromis niloticus (OnGrB), found that its function domain was conserved. Additionally, OnGrB was widely expressed in various tissues and could respond to T-cell activation in vitro at the transcriptional level. Furthermore, we prepared the recombinant OnGrB (rOnGrB) as an immunogen to develop a mouse anti-OnGrB monoclonal antibody (mAb). Using this anti-OnGrB mAb as a tool, we explored the expression of OnGrB in the adaptive immune response of tilapia. Our findings revealed that T cell was a significant source of OnGrB production, the expression of OnGrB at the protein level and the proportion of OnGrB + T cells increased after both T cell activation in vitro and infection with Edwardsiella piscicida in vivo. More importantly, our findings also preliminarily illuminated that p65 could regulate the transcriptional activity of OnGrB. These results indicated that OnGrB was involved in the adaptive immunity of tilapia and played a critical role in T cell function in teleost. Our study provided theoretical support and new perspectives for understanding adaptive immunity in teleost.

The TAK1/JNK axis participates in adaptive immunity by promoting lymphocyte activation in Nile tilapia.

The transforming growth factor beta-activated kinase 1 (TAK1)/c-Jun N-terminal kinase (JNK) axis is an essential MAPK upstream mediator and regulates immune signaling pathways. However, whether the TAK1/JNK axis harnesses the strength in regulation of signal transduction in early vertebrate adaptive immunity is unclear. In this study, by modeling on Nile tilapia (Oreochromis niloticus), we investigated the potential regulatory function of TAK1/JNK axis on lymphocyte-mediated adaptive immune response. Both OnTAK1 and OnJNK exhibited highly conserved sequences and structures relative to their counterparts in other vertebrates. Their mRNA was widely expressed in the immune-associated tissues, while phosphorylation levels in splenic lymphocytes were significantly enhanced on the 4th day post-infection by Edwardsiella piscicida. In addition, OnTAK1 and OnJNK were significantly up-regulated in transcriptional level after activation of lymphocytes in vitro by phorbol 12-myristate 13-acetate plus ionomycin (P + I) or PHA, accompanied by a predominant increase in phosphorylation level. More importantly, inhibition of OnTAK1 activity by specific inhibitor NG25 led to a significant decrease in the phosphorylation level of OnJNK. Furthermore, blocking the activity of OnJNK with specific inhibitor SP600125 resulted in a marked reduction in the expression of T-cell activation markers including IFN-γ, CD122, IL-2, and CD44 during PHA-induced T-cell activation. In summary, these findings indicated that the conserved TAK1/JNK axis in Nile tilapia was involved in adaptive immune responses by regulating the activation of lymphocytes. This study enriched the current knowledge of adaptive immunity in teleost and provided a new perspective for understanding the regulatory mechanism of fish immunity.

A Meta-analysis of the Efficacy of Different Surgical Methods in the Treatment of Uterine Prolapse.

AIM: The management of uterine prolapse poses a significant clinical challenge, with surgical intervention often necessary for symptom relief and restoration of pelvic floor function. However, the optimal surgical approach for uterine prolapse remains uncertain, prompting a comprehensive meta-analysis to compare the efficacy of various surgical methods. This study aims to assess the effectiveness of different surgical methods for treating uterine prolapse. METHODS: We used computer search to retrieve relevant literature to compare the therapeutic effects of different surgical methods for treating uterine prolapse. The search was conducted in the Web of Science and PubMed databases, and articles published until October 2023 were obtained. We employed random effects and fixed effects models and performed a meta-analysis using the R software. RESULTS: This study included 40 standard papers covering 25,896 patients with uterine prolapse. We used random and fixed effects models to conduct a meta-analysis of hysterectomy and uterine fixation procedures. The findings indicated that different surgical approaches had no significant impact on surgical success rates (I2 = 69%, p < 0.01; risk ratio (RR) (95% confidence intervals (CI)): 1.00 [0.98; 1.03]) or postoperative adverse reactions (I2 = 54%, p < 0.01; RR (95% CI), 1.10 [0.83; 1.45]). However, the durations of the surgical procedure for hysterectomy (I2 = 91%, p < 0.01; standardized mean difference (SMD) (95% CI), 0.78 [0.49; 1.07]), surgical blood loss (I2 = 97%, p < 0.01, SMD (95% CI): 1.14 [0.21; 2.07]), and intraoperative adverse reactions (I2 = 0%, p = 0.61, RR (95% CI): 1.37 [1.10; 1.71]) were statistically significant between hysterectomy and uterine fixation procedures. Additionally, publication bias and sensitivity tests showed no publication bias in this meta-analysis and no literature causing significant sensitivity. CONCLUSIONS: In the treatment of uterine prolapse, both hysterectomy and uterine fixation are similar in terms of surgical success rates and postoperative adverse reactions. However, hysterectomy is associated with longer duration of the surgical procedure, increased blood loss and higher incidence of intraoperative adverse reactions compared to uterine fixation.

Hyperosmotic Stress Induces Inflammation and Excessive Th17 Response to Blunt T-Cell Immunity in Tilapia.

Despite the advances in study on osmotic physiology in bony fish, the mechanism by which the immune system, especially T-cell immunity, adapts and responds to osmotic stress remains unknown. In the current study, we investigated the response of T cells to hyperosmotic stress in the bony fish Nile tilapia (Oreochromis niloticus). As a euryhaline fish, tilapia was able to adapt to a wide range of salinities; however, hypertonic stress caused inflammation and excessive T-cell activation. Furthermore, hypertonic stress increased the expression of IL-17A in T cells, upregulated the transcription factor RORα, and activated STAT3 signaling, along with IL-6- and TGF-ß1-mediated pathways, revealing an enhanced Th17 response in this early vertebrate. These hypertonic stress-induced events collectively resulted in an impaired antibacterial immune response in tilapia. Hypertonic stress elevated the intracellular ROS level, which in turn activated the p38-MK2 signaling pathway to promote IL-17A production by T cells. Both ROS elimination and the p38-MK2 axis blockade diminished the increased IL-17A production in T cells under hypertonic conditions. Moreover, the produced proinflammatory cytokines further amplified the hypertonic stress signaling via the MKK6-p38-MK2 axis-mediated positive feedback loop. To our knowledge, these findings represent the first description of the mechanism by which T-cell immunity responds to hypertonic stress in early vertebrates, thus providing a novel perspective for understanding the adaptive evolution of T cells under environmental stress.

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.

The strain regulated physical properties of PbI2/g-C3N4for potential optoelectronic device.

The van der Waals (vdW) heterostructures of Z-scheme PbI2/g-C3N4with an indirect bandgap have gained much attention in recent years due to their unique properties and potential applications in various fields. However, the optoelectronic characteristics and strain-modulated effects are not yet fully understood. By considering this, six stacking models of PbI2/g-C3N4are proposed and the stablest structure is selected for further investigation. The uniaxial and biaxial strains (-10%-10%) regulated band arrangement, charge distribution, optical absorption in the framework of density functional theory are systematically explored. The compressive uniaxial strain of -8.55% changes the band type from II→I, and the biaxial strains of -7.12%, -5.25%, 8.91% change the band type in a way of II→I→II→I, acting like the 'band-pass filter'. The uniaxial strains except -10% compressive strain, and the -6%, -4%, 2%, 4%, 10% biaxial strains will enhance the light absorption of PbI2/g-C3N4. The exerted strains on PbI2/g-C3N4generate different power conversion efficiency (ηPCE) values ranging from 3.64% to 25.61%, and the maximumηPCEis generated by -6% biaxial strain. The results of this study will pave the way for the development of new electronic and optoelectronic materials with customized properties in photocatalytic field and optoelectronic devices.

Fish Uses CTLA-4 Immune Checkpoint to Suppress mTORC1-Controlled T-Cell Glycolysis and Immunity.

As an immune checkpoint, cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) suppresses the activation, proliferation, and effector function of T cells, thus preventing an overexuberant response and maintaining immune homeostasis. However, whether and how this immune checkpoint functions in early vertebrates remains unknown. In the current study, using a Nile tilapia (Oreochromis niloticus) model, we investigated the suppression of T cell response by CTLA-4 in bony fish. Tilapia CTLA-4 is constitutively expressed in lymphoid tissues, and its mRNA and protein expression in lymphocytes are upregulated following PHA stimulation or Edwardsiella piscicida infection. Blockade of CTLA-4 signaling enhanced T cell activation and proliferation but inhibited activation-induced T cell apoptosis, indicating that CTLA-4 negatively regulated T cell activation. In addition, blocking CTLA-4 signaling in vivo increased the differentiation potential and cytotoxicity of T cells, resulting in an enhanced T cell response during E. piscicida infection. Tilapia CTLA-4 competitively bound the B7.2/CD86 molecule with CD28, thus antagonizing the CD28-mediated costimulatory signal of T cell activation. Furthermore, inhibition of mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling, c-Myc, or glycolysis markedly impaired the CTLA-4 blockade-enhanced T cell response, suggesting that CTLA-4 suppressed the T cell response of tilapia by inhibiting mTORC1/c-Myc axis-controlled glycolysis. Overall, the findings indicate a detailed mechanism by which CTLA-4 suppresses T cell immunity in tilapia; therefore, we propose that early vertebrates have evolved sophisticated mechanisms coupling immune checkpoints and metabolic reprogramming to avoid an overexuberant T cell response.

Full T-cell activation and function in teleosts require collaboration of first and co-stimulatory signals.

Mammalian T-cell responses require synergism between the first signal and co-stimulatory signal. However, whether and how dual signaling regulates the T-cell response in early vertebrates remains unknown. In the present study, we discovered that the Nile tilapia ( Oreochromis niloticus) encodes key components of the LAT signalosome, namely, LAT, ITK, GRB2, VAV1, SLP-76, GADS, and PLC-γ1. These components are evolutionarily conserved, and CD3ε mAb-induced T-cell activation markedly increased their expression. Additionally, at least ITK, GRB2, and VAV1 were found to interact with LAT for signalosome formation. Downstream of the first signal, the NF-κB, MAPK/ERK, and PI3K-AKT pathways were activated upon CD3ε mAb stimulation. Furthermore, treatment of lymphocytes with CD28 mAbs triggered the AKT-mTORC1 pathway downstream of the co-stimulatory signal. Combined CD3ε and CD28 mAb stimulation enhanced ERK1/2 and S6 phosphorylation and elevated NFAT1, c-Fos, IL-2, CD122, and CD44 expression, thereby signifying T-cell activation. Moreover, rather than relying on the first or co-stimulatory signal alone, both signals were required for T-cell proliferation. Full T-cell activation was accompanied by marked apoptosis and cytotoxic responses. These findings suggest that tilapia relies on dual signaling to maintain an optimal T-cell response, providing a novel perspective for understanding the evolution of the adaptive immune system.

The regulatory function of the d-orbital structure in TM@g-t-C4N3 for bifunctional catalysis of the oxygen evolution/reduction reaction.

Highly efficient catalysts for the oxygen evolution/reduction reaction (OER/ORR) have attracted great attention in research for energy devices with high conversion efficiency. Herein, systematic first-principles investigations are performed to explore the catalytic performance of graphitic C4N3 loaded with single transition metal atoms (TM@g-t-C4N3) for the OER/ORR. The results show that Fe, Co, Ni and Rh@g-t-C4N3 exhibit fascinating bifunctional catalytic activities for both the OER and ORR. Moreover, it is observed that better activities are easily achieved when the valence d orbitals of doped TM atoms are nearly fully occupied. Further analysis reveals the volcano relationship between the OER/ORR performance and the adsorption Gibbs free energy. The adsorption free energy of intermediates in the OER/ORR process is also found to highly correlate with the electronic structures of TM@g-t-C4N3, which are mainly characterized by two quantities, one is the descriptor φ related to the electronegativity and the number of valence electrons in d orbitals, and the other is the projected d band center. The results indicate that it is possible to predict the catalytic performance of TM@g-t-C4N3 by a detailed examination of the electronic properties of the doped TM atoms to some extent. This research not only provides several highly active g-t-C4N3-based single-atom catalysts (SACs) for the OER/ORR, but also reveals some potential regularities of SAC systems.

Cytokine networks that suppress fish cellular immunity.

Immunosuppressive cytokines are a class of cytokines produced by immune cells and certain non-immune cells that have a suppressive effect on immune function. Currently known immunosuppressive cytokines include interleukin (IL)-10, transforming growth factor beta (TGF-ß), IL-35, and IL-37. Although latest sequencing technologies have facilitated the identification of immunosuppressive cytokines in fish, IL-10 and TGF-ß were the most well-known ones that have been widely studied and received continuous attention. Fish IL-10 and TGF-ß have been identified as anti-inflammatory and immunosuppressive factors, acting on both innate and adaptive immune systems. However, unlike mammals, teleost fish underwent a third or fourth whole-genome duplication event, which significantly expanded the gene family associated with the cytokine signaling pathway, making the function and mechanism of these molecules need further investigation. In this review, we summarize the advances of studies on fish immunosuppressive cytokines IL-10 and TGF-ß since their identification, mainly focusing on production, signaling transduction, and effects on the immunological function. This review aims to expand the understanding of the immunosuppressive cytokine network in fish.

Dietary restriction to optimize T cell immunity is an ancient survival strategy conserved in vertebrate evolution.

Recent advances highlight a key role of transient fasting in optimizing immunity of human and mouse. However, it remains unknown whether this strategy is independently acquired by mammals during evolution or instead represents gradually evolved functions common to vertebrates. Using a tilapia model, we report that T cells are the main executors of the response of the immune system to fasting and that dietary restriction bidirectionally modulates T cell immunity. Long-term fasting impaired T cell immunity by inducing intense autophagy, apoptosis, and aberrant inflammation. However, transient dietary restriction triggered moderate autophagy to optimize T cell response by maintaining homeostasis, alleviating inflammation and tissue damage, as well as enhancing T cell activation, proliferation and function. Furthermore, AMPK is the central hub linking fasting and autophagy-controlled T cell immunity in tilapia. Our findings demonstrate that dietary restriction to optimize immunity is an ancient strategy conserved in vertebrate evolution, providing novel perspectives for understanding the adaptive evolution of T cell response.

Interleukin-12 induces IFN-γ secretion and STAT signaling implying its potential regulation of Th1 cell response in Nile tilapia.

As a pleiotropic cytokine consisting of IL-12p35 and IL-12p40, Interleukin-12 (IL-12) features in inflammation regulation and anti-bacterial immunity. While IL-12 homologs have been identified in non-mammalian species, the precise mechanisms by which IL-12 contributes to early adaptive immune responses in vertebrates remain incompletely understood. Herein, an evolutionary conserved Oreochromis niloticus IL-12 (defined as OnIL-12) was identified by synteny characterization, structural comparisons and phylogenetic pattern of IL-12p35b and IL-12p40a. IL-12p35b and IL-12p40a exhibited widespread expression in lymphoid-related tissues of tilapia, while their mRNA expression in head-kidney demonstrated a significant increase after Edwardsiella piscicida infection. Compared with other lymphocytes, recombinant OnIL-12 (rOnIL-12) displayed stronger affinity binding to T cells. Although stimulation of lymphocytes with the p35b or p40a subunit resulted in a significant induction of IFN-γ expression, rOnIL-12 showed stronger potential to promote IFN-γ expression than these subunits. rOnIL-12 not only elevated the mRNA expression level Th1 cell-associated transcription factor T-bet in lymphocytes, but also increased the proportion of CD4-1+IFN-γ+ lymphocytes. Moreover, the mRNA and phosphorylation levels of STAT1, STAT3, STAT4 and STAT5 were enhanced by rOnIL-12. These findings will offer previous evidence for further exploration into the regulatory mechanisms of Th1 cellular immunity in early vertebrates.

A novel magnetic bead-based immunoprecipitation method for anti-dense fine speckled 70 antibodies.

The indirect immunofluorescence assay (IIFA) on HEp-2 cells has been widely used for screening anti-nuclear antibodies (ANA) that are associated with systemic autoimmune rheumatic diseases (SARD). Sera containing ANA display multiple distinct fluorescence patterns on HEp-2 cells. Among them, a dense fine speckled (DFS) pattern caused by anti-DFS70 antibodies has been reported to have higher prevalence in healthy individuals than in patients with SARD. This DFS pattern is often difficult to distinguish amongst other SARD-associated ANA patterns, in particular a mixed homogeneous and speckled pattern. Furthermore, a strong DFS pattern can mask other SARD-associated patterns. Hence, we developed a novel immunoprecipitation method using magnetic beads to remove anti-DFS70 antibodies in serum prior to running IIFA. We also aimed to confirm the presence of anti-DFS70 and to uncover any SARD-associated ANA patterns masked by a strong DFS pattern. The sera used in our study were from 70 individuals who had routine ANA screen, of which 35 sera had an isolated DFS pattern with monospecific anti-DFS70 antibodies confirmed by a complementary assay, and 35 were control sera without a DFS pattern. An immunoprecipitation method using magnetic beads coated with recombinant human full length DFS70 protein was developed. The performance of this new method was evaluated in comparison to an immunoadsorption method using the same DFS70 protein. Our newly developed immunoprecipitation method demonstrated excellent sensitivity (91.4%) and specificity (100%) in confirming the DFS pattern associated with anti-DFS70 in sera. Additionally, our method was able to remove anti-DFS70 and uncover SARD-associated ANA patterns masked by a strong DFS pattern. It also showed a clearer background on IIFA than that of the immunoadsorption method. The novel magnetic bead-based immunoprecipitation method demonstrated satisfactory performance in removing anti-DFS70 without interfering with the detection of other antibodies. It can be easily integrated with IIFA to confirm anti-DFS70 associated DFS pattern. Additionally, it can simultaneously unmask other ANA patterns, which cannot be achieved by a conventional protocol that requires a complementary anti-DFS70 specific assay to be performed. Therefore, the novel method provides a more effective and accurate solution for ANA screening.

Glutamine Metabolism Underlies the Functional Similarity of T Cells between Nile Tilapia and Tetrapod.

As the lowest organisms possessing T cells, fish are instrumental for understanding T cell evolution and immune defense in early vertebrates. This study established in Nile tilapia models suggests that T cells play a critical role in resisting Edwardsiella piscicida infection via cytotoxicity and are essential for IgM+ B cell response. CD3 and CD28 monoclonal antibody crosslinking reveals that full activation of tilapia T cells requires the first and secondary signals, while Ca2+ -NFAT, MAPK/ERK, NF-κB, and mTORC1 pathways and IgM+ B cells collectively regulate T cell activation. Thus, despite the large evolutionary distance, tilapia and mammals such as mice and humans exhibit similar T cell functions. Furthermore, it is speculated that transcriptional networks and metabolic reprogramming, especially c-Myc-mediated glutamine metabolism triggered by mTORC1 and MAPK/ERK pathways, underlie the functional similarity of T cells between tilapia and mammals. Notably, tilapia, frogs, chickens, and mice utilize the same mechanisms to facilitate glutaminolysis-regulated T cell responses, and restoration of the glutaminolysis pathway using tilapia components rescues the immunodeficiency of human Jurkat T cells. Thus, this study provides a comprehensive picture of T cell immunity in tilapia, sheds novel perspectives for understanding T cell evolution, and offers potential avenues for intervening in human immunodeficiency.

Evolutionarily conserved IL-27ß enhances Th1 cells potential by triggering the JAK1/STAT1/T-bet axis in Nile tilapia.

As a pleiotropic cytokine in the interleukin (IL)-12 family, IL-27ß plays a significant role in regulating immune cell responses, eliminating invading pathogens, and maintaining immune homeostasis. Although non-mammalian IL-27ß homologs have been identified, the mechanism of whether and how it is involved in adaptive immunity in early vertebrates remains unclear. In this study, we identified an evolutionarily conserved IL-27ß (defined as OnIL-27ß) from Nile tilapia (Oreochromis niloticus), and explored its conserved status through gene collinearity, gene structure, functional domain, tertiary structure, multiple sequence alignment, and phylogeny analysis. IL-27ß was widely expressed in the immune-related tissues/organ of tilapia. The expression of OnIL-27ß in spleen lymphocytes increased significantly at the adaptive immune phase after Edwardsiella piscicida infection. OnIL-27ß can bind to precursor cells, T cells, and other lymphocytes to varying degrees. Additionally, IL-27ß may be involved in lymphocyte-mediated immune responses through activation of Erk and JNK pathways. More importantly, we found that IL-27ß enhanced the mRNA expression of the Th1 cell-associated cytokine IFN-γ and the transcription factor T-bet. This potential enhancement of the Th1 response may be attributed to the activation of the JAK1/STAT1/T-bet axis by IL-27ß, as it induced increased transcript levels of JAK1, STAT1 but not TYK2 and STAT4. This study provides a new perspective for understanding the origin, evolution and function of the adaptive immune system in teleost.

Hyper-IgM and acquired C1q complement deficiency in a patient with de novo ATM mutation.

Hyper-IgM syndrome (HIGM) is a rare immunodeficiency phenotype that is usually accompanied by serious infections. We present a curious case of the incidental detection of HIGM in a 45-year-old male with complement C1q deficiency. He had relatively mild sinopulmonary infections, recurrent skin infections and lipomas in his adulthood. Investigations revealed normal enumeration of total peripheral blood B cells and reduced expression of CD40L on his CD4+ T cells. C1q was noted to be absent, due to a peripheral inhibitor such as an autoantibody. Genomic sequencing of the patient and his parents revealed a novel, de novo heterozygous mutation in the ATM (ataxia telangiectasia mutated) gene although he displayed no clinical evidence of ataxia telangiectasia. This is a rare case of HIGM and acquired C1q deficiency. We present full phenotyping data that contributes to the growing understanding to these interesting immunodeficiencies.

IL-10 Negatively Controls the Primary T Cell Response of Tilapia by Triggering the JAK1/STAT3/SOCS3 Axis That Suppresses NF-κB and MAPK/ERK Signaling.

The braking mechanisms to protect the host from tissue damage and inflammatory disease caused by an overexuberant immune response are common in many T cell subsets. However, the negative regulation of T cell responses and detailed mechanisms are not well understood in early vertebrates. In the current study, using a Nile tilapia (Oreochromis niloticus) model, we investigated the suppression of T cell immunity by IL-10. Tilapia encodes an evolutionarily conserved IL-10, whose expression in lymphocytes is markedly induced during the primary adaptive immune response against Aeromonas hydrophila infection. Activated T cells of tilapia produce IL-10, which in turn inhibits proinflammatory cytokine expression and suppresses PHA-induced T cell activation. Moreover, administration of IL-10 impairs the proliferation of tilapia T cells, reduces their potential to differentiate into Th subsets, and cripples the cytotoxic function, rendering the animals more vulnerable to pathogen attack. After binding to its receptor IL-10Ra, IL-10 activates the JAK1/STAT3 axis by phosphorylation and enhances the expression of the suppressor of cytokine signaling 3 (SOCS3), which in turn attenuates the activation of the NF-κB and MAPK/ERK signaling pathways, thus suppressing the T cell response of tilapia. Our findings elucidate a negative regulatory mechanism of T cell immunity in a fish species and support the notion that the braking mechanism of T cells executed through IL-10 existed prior to the divergence of the tetrapod lineage from teleosts. Therefore, this study, to our knowledge, provides a novel perspective on the evolution of the adaptive immune system.

TGF-ß1 suppresses the T-cell response in teleost fish by initiating Smad3- and Foxp3-mediated transcriptional networks.

Transforming growth factor-ß1 (TGF-ß1) can suppress the activation, proliferation, and function of many T-cell subsets, protecting organisms from inflammatory and autoimmune disease caused by an overexuberant immune response. However, whether and how TGF-ß1 regulates T-cell immunity in early vertebrates remain unknown. Here, using a Nile tilapia (Oreochromis niloticus) model, we investigated suppression of the T-cell response by TGF-ß1 in teleost species. Tilapia encodes an evolutionarily conserved TGF-ß1, the expression of which in lymphocytes is significantly induced during the immune response following Edwardsiella piscicida infection. Once activated, tilapia T cells increase TGF-ß1 production, which in turn suppresses proinflammatory cytokine expression and inhibits T-cell activation. Notably, we found administration of TGF-ß1 cripples the proliferation of tilapia T cells, reduces the potential capacity of Th1/2 differentiation, and impairs the cytotoxic function, rendering the fish more vulnerable to bacterial infection. Mechanistically, TGF-ß1 initiates the TGF-ßR/Smad signaling pathway and triggers the phosphorylation and nuclear translocation of Smad2/3. Smad3 subsequently interacts with several transcriptional partners to repress transcription of cytokines IL-2 and IFN-γ but promote transcription of immune checkpoint regulator CTLA4 and transcription factor Foxp3. Furthermore, TGF-ß1/Smad signaling further utilizes Foxp3 to achieve the cascade regulation of these T-cell genes. Taken together, our findings reveal a detailed mechanism by which TGF-ß1 suppresses the T cell-based immunity in Nile tilapia and support the notion that TGF-ß1 had already been employed to inhibit the T-cell response early in vertebrate evolution, thus providing novel insights into the evolution of the adaptive immune system.