The scale of zebrafish pectoral fin buds is determined by intercellular K+ levels and consequent Ca2+-mediated signaling via retinoic acid regulation of Rcan2 and Kcnk5b.

K+ channels regulate morphogens to scale adult fins, but little is known about what regulates the channels and how they control morphogen expression. Using the zebrafish pectoral fin bud as a model for early vertebrate fin/limb development, we found that K+ channels also scale this anatomical structure, and we determined how one K+-leak channel, Kcnk5b, integrates into its developmental program. From FLIM measurements of a Förster Resonance Energy Transfer (FRET)-based K+ sensor, we observed coordinated decreases in intracellular K+ levels during bud growth, and overexpression of K+-leak channels in vivo coordinately increased bud proportions. Retinoic acid, which can enhance fin/limb bud growth, decreased K+ in bud tissues and up-regulated regulator of calcineurin (rcan2). rcan2 overexpression increased bud growth and decreased K+, while CRISPR-Cas9 targeting of rcan2 decreased growth and increased K+. We observed similar results in the adult caudal fins. Moreover, CRISPR targeting of Kcnk5b revealed that Rcan2-mediated growth was dependent on the Kcnk5b. We also found that Kcnk5b enhanced depolarization in fin bud cells via Na+ channels and that this enhanced depolarization was required for Kcnk5b-enhanced growth. Lastly, Kcnk5b-induced shha transcription and bud growth required IP3R-mediated Ca2+ release and CaMKK activity. Thus, we provide a mechanism for how retinoic acid via rcan2 can regulate K+-channel activity to scale a vertebrate appendage via intercellular Ca2+ signaling.

NAT10 Is Involved in Cardiac Remodeling Through ac4C-Mediated Transcriptomic Regulation.

BACKGROUND: Heart failure, characterized by cardiac remodeling, is associated with abnormal epigenetic processes and aberrant gene expression. Here, we aimed to elucidate the effects and mechanisms of NAT10 (N-acetyltransferase 10)-mediated N4-acetylcytidine (ac4C) acetylation during cardiac remodeling. METHODS: NAT10 and ac4C expression were detected in both human and mouse subjects with cardiac remodeling through multiple assays. Subsequently, acetylated RNA immunoprecipitation and sequencing, thiol-linked alkylation for the metabolic sequencing of RNA (SLAM-seq), and ribosome sequencing (Ribo-seq) were employed to elucidate the role of ac4C-modified posttranscriptional regulation in cardiac remodeling. Additionally, functional experiments involving the overexpression or knockdown of NAT10 were conducted in mice models challenged with Ang II (angiotensin II) and transverse aortic constriction. RESULTS: NAT10 expression and RNA ac4C levels were increased in in vitro and in vivo cardiac remodeling models, as well as in patients with cardiac hypertrophy. Silencing and inhibiting NAT10 attenuated Ang II-induced cardiomyocyte hypertrophy and cardiofibroblast activation. Next-generation sequencing revealed ac4C changes in both mice and humans with cardiac hypertrophy were associated with changes in global mRNA abundance, stability, and translation efficiency. Mechanistically, NAT10 could enhance the stability and translation efficiency of CD47 and ROCK2 transcripts by upregulating their mRNA ac4C modification, thereby resulting in an increase in their protein expression during cardiac remodeling. Furthermore, the administration of Remodelin, a NAT10 inhibitor, has been shown to prevent cardiac functional impairments in mice subjected to transverse aortic constriction by suppressing cardiac fibrosis, hypertrophy, and inflammatory responses, while also regulating the expression levels of CD47 and ROCK2 (Rho associated coiled-coil containing protein kinase 2). CONCLUSIONS: Therefore, our data suggest that modulating epitranscriptomic processes, such as ac4C acetylation through NAT10, may be a promising therapeutic target against cardiac remodeling.

How brain structure-function decoupling supports individual cognition and its molecular mechanism.

Functional signals emerge from the structural network, supporting multiple cognitive processes through underlying molecular mechanism. The link between human brain structure and function is region-specific and hierarchical across the neocortex. However, the relationship between hierarchical structure-function decoupling and the manifestation of individual behavior and cognition, along with the significance of the functional systems involved, and the specific molecular mechanism underlying structure-function decoupling remain incompletely characterized. Here, we used the structural-decoupling index (SDI) to quantify the dependency of functional signals on the structural connectome using a significantly larger cohort of healthy subjects. Canonical correlation analysis (CCA) was utilized to assess the general multivariate correlation pattern between region-specific SDIs across the whole brain and multiple cognitive traits. Then, we predicted five composite cognitive scores resulting from multivariate analysis using SDIs in primary networks, association networks, and all networks, respectively. Finally, we explored the molecular mechanism related to SDI by investigating its genetic factors and relationship with neurotransmitter receptors/transporters. We demonstrated that structure-function decoupling is hierarchical across the neocortex, spanning from primary networks to association networks. We revealed better performance in cognition prediction is achieved by using high-level hierarchical SDIs, with varying significance of different brain regions in predicting cognitive processes. We found that the SDIs were associated with the gene expression level of several receptor-related terms, and we also found the spatial distributions of four receptors/transporters significantly correlated with SDIs, namely D2, NET, MOR, and mGluR5, which play an important role in the flexibility of neuronal function. Collectively, our findings corroborate the association between hierarchical macroscale structure-function decoupling and individual cognition and provide implications for comprehending the molecular mechanism of structure-function decoupling. PRACTITIONER POINTS: Structure-function decoupling is hierarchical across the neocortex, spanning from primary networks to association networks. High-level hierarchical structure-function decoupling contributes much more than low-level decoupling to individual cognition. Structure-function decoupling could be regulated by genes associated with pivotal receptors that are crucial for neuronal function flexibility.

Decoding molecular features of bovine oocyte fate during antral follicle growth via single-cell multi-omics analysis†.

Antral follicle size is a useful predictive marker of the competency of enclosed oocytes for yielding an embryo following in vitro maturation and fertilization. However, the molecular mechanisms underpinning oocyte developmental potential during bovine antral follicle growth are still unclear. Here, we used a modified single-cell multi-omics approach to analyze the transcriptome, DNA methylome, and chromatin accessibility in parallel for oocytes and cumulus cells collected from bovine antral follicles of different sizes. Transcriptome profiling identified three types of oocytes (small, medium, and large) that underwent different developmental trajectories, with large oocytes exhibiting the largest average follicle size and characteristics resembling metaphase-II oocytes. Differential expression analysis and real-time polymerase chain reaction assay showed that most replication-dependent histone genes were highly expressed in large oocytes. The joint analysis of multi-omics data revealed that the transcription of 20 differentially expressed genes in large oocytes was associated with both DNA methylation and chromatin accessibility. In addition, oocyte-cumulus interaction analysis showed that inflammation, DNA damage, and p53 signaling pathways were active in small oocytes, which had the smallest average follicle sizes. We further confirmed that p53 pathway inhibition in the in vitro maturation experiments using oocytes obtained from small antral follicles could improve the quality of oocytes and increased the blastocyte rate after in vitro fertilization and culture. Our work provides new insights into the intricate orchestration of bovine oocyte fate determination during antral folliculogenesis, which is instrumental for optimizing in vitro maturation techniques to optimize oocyte quality.

Explore genetic susceptibility association between viral infections and Guillain-Barré syndrome risk using two-sample Mendelian randomization.

BACKGROUND: Numerous observational studies have indicated that patients with Guillain-Barré syndrome (GBS) frequently had infections with various pathogens before the onset of the disease, particularly several viral infections. Some of these infections are linked to specific clinical and immunological subgroups of GBS, suggesting a potential correlation between viral infections and the development of GBS. However, observational studies have several limitations, including the presence of confounding factors. METHOD: We explored the potential correlation between HIV, SARS-CoV-2, varicella-zoster virus, herpes simplex virus, Epstein-Barr virus, hepatitis B virus, and influenza virus with GBS using a two-sample Mendelian randomization approach. The data was derived from published summary statistics from genome-wide association studies (GWAS). After removing linkage disequilibrium, selecting strong instrumental variables and addressing confounding factors, we would conduct a two-sample Mendelian randomization analysis along with sensitivity testing and the MR-Steiger directional test. RESULT: HIV may have a causal association with GBS (IVW: p = 0.010, OR [95% CI] 1.240 [1.052-1.463]), while no such relationship exists with COVID-19 (IVW: p = 0.275, OR [95% CI] 0.831[0.596-1.159]), varicella (IVW: p = 0.543, OR [95% CI] 0.919 [0.701-1.206]), herpes zoster (IVW: p = 0.563, OR [95% CI] 0.941 [0.766-1.156]), HSV (IVW: p = 0.280, OR [95% CI] 1.244 [0.837-1.851]), EBV (IVW: p = 0.218, OR [95% CI] 0.883 [0.724-1.076]), HBV (IVW: p = 0.179, OR [95% CI] 1.072 [0.969-1.187]), or influenza virus (IVW: p = 0.917, OR [95% CI] 0.971 [0.553-1.703]). We did not find any abnormal SNPs, pleiotropy, or heterogeneity, nor is there any reverse causation. CONCLUSION: Our study results indicate a causal relationship between HIV and GBS, providing new research directions for the etiology of GBS.

Induction Therapy of Tislelizumab Combined with Cisplatin and 5-Fluorouracil and Subsequent Conversion Surgery in Patients with Unresectable Advanced Esophageal Squamous Cell Carcinoma: A Phase 2, Single Center Study.

BACKGROUND: This study reported the safety and efficacy of a phase 2, open-label, single-arm, exploratory clinical trial of induction immunochemotherapy in patients with initially unresectable advanced esophageal squamous cell carcinoma (ESCC). PATIENTS AND METHODS: Patients underwent three cycles of induction therapy with tislelizumab, cisplatin, and 5-fluorouracil. The primary endpoints were the safety, major pathological response (MPR), and pathological complete response (pCR). Secondary endpoints included the R0 resection rate, disease-free survival (DFS), and overall survival (OS). Genomic data and immune microenvironment data were analyzed exploratively. RESULTS: The treatment was safe, with a grade 3 or higher adverse event rate of 14.9% (7/47). Of the total 47 patients enrolled in the study, 19 (40.4%) achieved MPR, 12 (25.5%) achieved pCR, 4 (8.5%) achieved complete clinical response (cCR) and declined surgery, and 23 (48.94%) underwent successful resection. Median follow-up was 18 months, with a median DFS of 24 months, a median OS of 36 months. A high tumor mutation burden was associated with a better prognosis for patients who underwent surgery. Patients who achieved pCR had higher levels of immune cell infiltration and a greater proportion and concentration of tertiary lymphoid structures compared with those who experienced a major pathological response. CONCLUSIONS: Tislelizumab combined with chemotherapy is effective for ESCC, yielding high cCR, pCR, surgical conversion, and R0 resection rates, and tolerable adverse events. TRIAL REGISTRATION: NCT05469061.

Delivery of nanosecond laser pulses by multi-mode anti-resonant hollow core fiber at 1†µm wavelength.

In this paper we explore the application of low-loss multimode anti-resonant hollow-core fiber (MM-AR-HCF) in the delivery of nanosecond laser pulses at 1 µm wavelength. MM-AR-HCF with large core offers a rich content of low-loss higher-order modes which plays a key role in the efficient coupling and transmission of high-power laser of low beam quality. In the experiment, laser pulses of an average pulse energy of 21.8 mJ with 14.6 ns pulse width (corresponding a peak power of 1.49 MW) are transmitted through MM-AR-HCF of 9.8 m length without damage. 85% transmission efficiency is achieved where the incident laser beam suffers a low beam quality with M2 x and M2 y of 2.18 and 1.99 respectively. Laser-induced damage threshold (LIDT) of MM-AR-HCF was measured to be 22.6 mJ for 85% transmission efficiency, which is 7 times higher than that for a multimode silica optical fiber with a large core of 200 µm.

Alantolactone enhances the sensitivity of melanoma to MAPK pathway inhibitors by targeting inhibition of STAT3 activation and down-regulating stem cell markers.

Mitogen-activated protein kinase inhibitors (MAPKi) were the first line drugs for advanced melanoma patients with BRAF mutation. Targeted therapies have significant therapeutic effects; however, drug resistance hinders their long-term efficacy. Therefore, the development of new therapeutic strategies against MAPKi resistance is critical. Our previous results showed that MAPKi promote feedback activation of STAT3 signaling in BRAF-mutated cancer cells. Studies have shown that alantolactone inhibited the activation of STAT3 in a variety of tumor cells. Our results confirmed that alantolactone suppressed cell proliferation and promoted apoptosis by inhibiting STAT3 feedback activation induced by MAPKi and downregulating the expression of downstream Oct4 and Sox2. The inhibitory effect of alantolactone combined with a MAPKi on melanoma cells was significantly stronger than that on normal cells. In vivo and in vitro experiments showed that combination treatment was effective against drug-resistant melanomas. Our research indicates a potential novel combination therapy (alantolactone and MAPKi) for patients with BRAF-mutated melanoma.

Connection between Mechanical Relaxation and Equilibration Kinetics in a High-Entropy Metallic Glass.

The slow transition from an out-of-equilibrium glass towards a supercooled liquid is a complex relaxation phenomenon. In this Letter, we study the correlation between mechanical relaxation and equilibration kinetics in a Pd_{20}Pt_{20}Cu_{20}Ni_{20}P_{20} high-entropy metallic glass. The evolution of stress relaxation with aging time was obtained with an unprecedented detail, allowing us to pinpoint new interesting features. The long structural relaxation towards equilibrium contains a wide distribution of activation energies, instead of being just associated to the ß relaxation as commonly accepted. The stress relaxation time can be correlated with the equilibration rate and we observe a decrease of microstructural heterogeneity which contrasts with an increase of dynamic heterogeneity. These results significantly enhance our insight of the interplay between relaxation dynamics and thermodynamics in metallic glasses.

Construction of Covalent Triazine Frameworks with Electronic Donor-Acceptor System for Efficient Photocatalytic C-H Hydroxylation of Imidazole[1,2-α]Pyridine Derivatives.

Covalent triazine frameworks (CTFs) are promising heterogeneous photocatalyst candidates owing to their excellent stability, conjugacy, and tunability. In this study, a series of CTFs decorated with different substituents (H, MeO, and F) were synthesised and utilised as photocatalysts for C-H activation reactions. The corresponding optoelectronic properties could be precisely regulated by the electronic effects of different substituents in the nanopore channels of the CTFs; these CTFs were effective photocatalysts for C-H activation in organic synthesis due to their unique structures and optoelectronic properties. Methoxy-substituted CTF (MeO-CTF) exhibited extraordinary catalytic performance and reusability in C-H functionalization by constructing an electronic donor-acceptor system, achieving the highest yield in the photocatalytic C3-H hydroxylation of 2-phenylimidazole[1,2-α]pyridine. This strategy provides a new scaffold for the rational design of CTFs as efficient photocatalysts for organic synthesis.

CLIC1-mediated autophagy confers resistance to DDP in gastric cancer.

Gastric cancer has been a constant concern to researchers as one of the most common malignant tumors worldwide. The treatment options for gastric cancer include surgery, chemotherapy and traditional Chinese medicine. Chemotherapy is an effective treatment for patients with advanced gastric cancer. Cisplatin (DDP) has been approved as a critical chemotherapy drug to treat various kinds of solid tumors. Although DDP is an effective chemotherapeutic agent, many patients develop drug resistance during treatment, which has become a severe problem in clinical chemotherapy. This study aims to investigate the mechanism of DDP resistance in gastric cancer. The results show that intracellular chloride channel 1 (CLIC1) expression was increased in AGS/DDP and MKN28/DDP, and as compared to the parental cells, autophagy was activated. In addition, the sensitivity of gastric cancer cells to DDP was decreased compared to the control group, and autophagy increased after overexpression of CLIC1. On the contrary, gastric cancer cells were more sensitive to cisplatin after transfection of CLIC1siRNA or treatment with autophagy inhibitors. These experiments suggest that CLIC1 could alter the sensitivity of gastric cancer cells to DDP by activating autophagy. Overall, the results of this study recommend a novel mechanism of DDP resistance in gastric cancer.

Targeting tumorous Circ-E-Cadherinencoded C-E-Cad inhibits the recruitment and function of breast cancer-associated myeloid-derived suppressor cells.

We previously demonstrated that the C-E-cad protein encoded by circ-E-cadherin promotes the self-renewal of glioma stem cells. The expression pattern of C-E-cad in breast cancer and its potential function in the tumor microenvironment are unclear. The expression of circ-E-cadherin and C-E-cad was detected in breast cancer specimens. The influence of C-E-cad expression on MDSCs was assessed using FACS and in vivo tumorigenesis experiments. The synergistic effect of anti-C-E-cad and anti-PD-1 antibodies was validated in vivo. circ-E-cadherin and the encoded protein C-E-cad were found to be upregulated in breast cancer vs. normal samples. C-E-cad promotes the recruitment of MDSCs, especially PMN-MDSCs. C-E-cad activates EGFR signaling in tumor cells and promotes the transcription of CXCL8; moreover, C-E-cad binds to MDSCs and maintains glycolysis in PMN-MDSCs. Targeting C-E-cad enhanced anti-PD-1 efficiency. Our data suggested that C-E-cad is markedly overexpressed in breast cancer and promotes MDSC recruitment and survival. Targeting C-E-cad increases the efficacy of immune checkpoint inhibitor therapy.

TCCA/RSeSeR-Mediated Selenoalkoxy of Allenamides via a Radical Process: Synthesis of Selanyl-allylic N,O-Aminals.

An efficient TCCA (trichloroisocyanuric acid)/RSeSeR-mediated selenoalkoxy of allenamides for the construction of selanyl-allylic N,OA-aminal derivatives was developed. The reaction exhibits good functional group tolerance and high efficiency, affording the products in good to excellent yields. Mechanistic investigations indicated that a selanyl-allylic radical intermediate was first formed via the RSe radical added to the central carbon of allenamides, which subsequently furnished highly stable selanyl-allylic carbocation intermediate by abstraction of an electron by the chlorine radical. Moreover, this is the first report of using selenium reagent (RSeCl) to activate allenamides via a radical process.

Photocatalyzed C3-H Nitrosylation of Imidazo[1,2-a]pyridine under Continuous Flow and External Photocatalyst-, Oxidant-, and Additive-Free Conditions.

This study reports a protocol for the highly regioselective photocatalyzed C-H nitrosylation of imidazo[1,2-a]pyridine scaffolds at the C3 position under a combination of visible-light irradiation and continuous flow without any external photocatalyst. This protocol involves mild and safe conditions and shows good tolerance to air and water along with excellent functional group compatibility and site selectivity, generating various 3-nitrosoimidazo[1,2-a]pyridines in excellent yields under photocatalyst-, oxidant-, and additive-free conditions.Notably, the proposed nitrosylation reaction, which introduces the chromophore NO into imidazo[1,2-a]pyridine scaffolds, occurs efficiently under visible-light irradiation without any additional photocatalyst owing to the intense light-absorption characteristics of the nitrosylation products. This study could guide future studies on the development of green organic-synthesis strategies with a wide variety of potential applications.

A Systematic Review and Quality Assessment of Cardiovascular Disease-Specific Health-Related Quality-of-Life Instruments Part I: Instrument Development and Content Validity.

OBJECTIVES: Health-related quality-of-life (HRQoL) instruments for cardiovascular diseases (CVD) have been commonly used to measure important patient-reported outcomes (PROs) in clinical trials and practices. This study aimed at systematically identifying and assessing the content validity of CVD-specific HRQoL instruments in clinical studies. METHODS: The research team searched Cumulative Index to Nursing and Allied Health Literature, Embase, and PubMed from inception to January 20, 2022. The research team included studies that reported the development and content validity for CVD-specific instruments. Two reviewers independently assessed the methodological quality using the Consensus-based Standards for the Selection of Health Measurement Instruments methods on evaluating content validity of PROs. Content analysis was used to categorize the items included in the instruments. RESULTS: The research team found 69 studies reporting the content validity of 40 instruments specifically developed for CVD. Fourteen (35.0%) were rated "sufficient" with very low to moderate quality of evidence. For PRO development, all instruments were rated "doubtful" or "inadequate." Twenty-eight (70.0%) instruments cover the core concepts of HRQoL. CONCLUSIONS: The quality of development and content validity vary among existing CVD-specific instruments. The evidence on the content validity should be considered when choosing a HRQoL instrument in CVD clinical studies and health economic evaluations.

Validation of China Health-Related Outcomes Measures-Cardiovascular Disease.

OBJECTIVES: China Health-Related Outcomes Measures (CHROME) was an initiative aimed at developing a system of preference-based health-related quality of life instruments for China. CHROME-cardiovascular disease (CVD) is a CVD-specific instrument with 14 items developed under this initiative. This study aimed to test the psychometric properties of CHROME-CVD. METHODS: This validation study was conducted using cross-sectional questionnaire survey in China. Eligible patients with CVD were recruited and asked to complete the CHROME-CVD, the EQ-5D-5L, and a CVD-specific nonpreference-based health-related quality of life instrument selected according to the confirmed diagnosis of the patients. Item evaluation, internal consistency, measurement invariance, test-retest reliability, structural validity, and construct validity were tested using classic test theory. Item response theory was used to evaluate item-level performance. RESULTS: A total of 444 patients with CVD (coronary artery disease, n = 276, heart failure, n = 104, angina, n = 33, and atrial fibrillation, n = 16) from 6 provinces in China were enrolled for the validation. Exploratory factor analysis identified 4 factors: chest pain, other symptoms, physical health, and mental and social health. Cronbach's alpha and intraclass correlation coefficient were >0.8. A total of 20 of 26 (76.9%), and 90 of 95 (94.7%) predefined hypotheses were met for convergent and discriminant validities, respectively. No important difference was identified between subgroups of gender and residency. Response options of 10 items were found overlapped based on categorical response curves, which led to modification to 4-level response options. Wording of 3 items were modified by referring wordings of reference instruments. CONCLUSION: The validation of the CHROME-CVD demonstrated generally good psychometric properties. Further validation on the modified CHROME-CVD is needed.

Design and Construction of Carbon-Coated Bimetallic Selenide Heterostructures Loaded on Reduced Graphene Oxide Substrate for Superior Lithium-Ion Storage.

In this work, carbon-coated bimetallic tin-nickel selenide heterostructures loaded on reduced graphene oxide composites were prepared through a metal-organic framework-assisted strategy. The carbon coating mitigates the volume expansion and maintains the structural stability, while the introduction of reduced graphene oxide and heterojunction enhances electrical conductivity and reaction kinetics, thereby together contributing to the enhanced lithium-ion storage performance. As expected, the optimal material delivers excellent lithium-ion storage performance in terms of a high reversible capacity of 1033.4 mAh g-1 at 0.2 A g-1, outstanding rate capability, and long-term cyclability with the capacity of 726.2 mAh g-1 after 500 cycles at 1.0 A g-1 and 452.4 mAh g-1 after 1000 cycles at 2.0 A g-1. Furthermore, the electrochemical reaction mechanism of the composite is analyzed.

PoIL8-L, a teleost interleukin-8 like, enhances leukocyte cellular vitality and host defense against bacterial infections in Japanese flounder (Paralichthys olivaceus).

Interleukin-8 (IL-8), a CXC chemokine, exerts pivotal effect on cell migration, inflammatory response, and immune regulation. In this study, we examined the immunological characteristics of an IL-8 like homologue (PoIL8-L) in Japanese flounder (Paralichthys olivaceus). PoIL8-L contains a conserved chemokine CXC domain and 105 amino acid residues. PoIL8-L expression in tissues was constitutive, and significantly regulated by V. havieri or E. tarda infection. In vitro, rPoIL8-L could bind to eight tested bacteria, exhibited bacteriostatic and bactericidal effects against certain bacteria, and could bind to the targeted bacterial Ⅳ pilin protein rPilA of E. tarda. Furthermore, rPoIL8-L could attach to peripheral blood leukocytes, and enhance their immune genes expression, respiratory burst, chemotaxis, proliferation, acid phosphatase activity, and phagocytic activity. Additionally, rPoIL8-L induce neutrophils to extrude neutrophil extracellular traps. In vivo, rPoIL8-L could promote host resistance to E. tarda infection. In summary, these findings provide fresh perspectives on the immunological antibacterial properties of IL-8 in teleost.

PoCXCL8, a teleost chemokine, exerts direct bactericidal, chemotactic/phagocytic, and NETs releasing properties, promoting host anti-bacterial immunity.

As an important CXC chemokine, CXCL8 plays pleiotropic roles in immunological response. In teleost, CXCL8 is involved in cell migration and bacterial invasion. However, the immune antibacterial function of CXCL8 in Japanese flounder (Paralichthys olivaceus) (PoCXCL8) is largely scarce. In this research, we investigated the antibacterial property and leukocyte activation of PoCXCL8. PoCXCL8 consists of 100 amino acid residues, with a conserved chemokine CXC domain. PoCXCL8 was expressed in various tissues, with the highest level in liver and the lowest level in muscle, and sharply induced by V. harveyi or E. tarda in liver, spleen, and head kidney. In vitro, the recombinant PoCXCL8 (rPoCXCL8) could bind to Bacillus subtilis, Edwardsiella tarda, Escherichia coli, Pseudomonas fluorescens, Vibrio anguillarum, Vibrio harveyi, Staphylococcus aureus, and Micrococcus luteus, affect the growth of E. coli, E. tarda, M. luteus, and P. fluorescens, and have a direct bactericidal effect on E. coli and E. tarda. Moreover, rPoCXCL8 was able to bind the outer membranal protein rPilA of E. tarda. In addition, rPoCXCL8 could bind to PBLs, activating the PBLs activity including chemotaxis, proliferation, phagocytosis, reactive oxygen species, acid phosphatase activity. At same time, rPoCXCL8 could induce neutrophil to generate neutrophil extracellular traps (NETs) and promote the expression of inflammatory genes including IL-1ß, IL6, MMP13, TNF-α, and NF-κB. In flounder, the presence of rPoCXCL8 could enhance the in vivo resistance to E. tarda in liver, spleen, and head kidney. Moreover, the PoCXCL8-deficient could attenuate the fish defense against E. tarda infection in in spleen and head kidney. In conclusion, these results provided new insights into the antibacterial properties of CXCL8 in P. olivaceus.

CsIL-20, a tongue sole interleukin-20, negatively mediates leucocyte activity and antibacterial defense.

Interleukin-20 (IL-20), as an essential member of IL-10 family, plays vital roles in mammalian immunological response such as antimicrobial, inflammation, hematopoiesis, and immune diseases. In teleost, the study about immune antimicrobial function of IL-20 is largely scarce. In this article, we revealed the expression profiles and the immunological functions of the IL-20 (CsIL-20) in tongue sole Cynoglossus semilaevis. CsIL-20 is composed of 183 amino acid residues, with seven cysteine residues and a typical IL-10 domain which comprises six α-helices and two ß-sheets, and shares 34.4-71.2 % identities with other teleost IL-20. CsIL-20 was constitutively expressed in a variety of tissues and regulated by bacterial invasion, and the recombinant CsIL-20 (rCsIL-20) could bind to different bacteria. In vitro rCsIL-20 could interact with the membrane of peripheral blood leukocytes (PBLs), leading to the attenuation of reactive oxygen species (ROS) production and acid phosphatase activity in PBLs. In line with In vitro results, In vivo rCsIL-20 could obviously suppressed the host immune against bacterial infection. Furthermore, knockdown of CsIL-20 in vivo could markedly enhance the host antibacterial immunity. Collectively, these observations offer new insights into the negative effect of CsIL-20 on antibacterial immunity.