HD11 Cells Research Articles

Paeoniflorin inhibits APEC-induced inflammation in HD11 cells through the NF-κB signaling pathway by activating CB2R

Paeoniflorin inhibits APEC-induced inflammation in HD11 cells through the NF-κB signaling pathway by activating CB2R

Arbutin alleviates Mycoplasma gallinarum-induced damage caused by pulmonary fibrosis via the JAK2/STAT3 pathway

Mycoplasma gallinarum (MG) can cause infectious respiratory diseases in poultry that are chronic. Arbutin (AR) possesses anti-inflammatory, bacteriostatic, antitussive, and expectorant pharmacological effects, but whether it exerts regulatory effects on MG-induced pneumonia and fibrosis remains unclear. The study results unveiled that pulmonary connective tissue hyperplasia, pulmonary capillary congestion, and inflammatory cell infiltration, as well as serum levels of cytokines (i.e., TNF-α, IL-1β, IL-6, and IL-10), were elevated after MG infection. Collagen fibers were significantly deposited in the lung tissue from MG-infected chicks. Furthermore, the expression levels of key factors in the JAK2/STAT3 and TGF-β/Smad pathways markedly increased. AR intervention significantly alleviated MG-induced pneumonic injury, and reduced collagen deposition and the expression of fibrosis markers in the lung tissue. AR reduced the degree of pulmonary fibrosis by regulating key factors of the JAK2/STAT3 signaling pathway in the MG-infected HD11 cells. Thus, AR effectively reduced the expression of inflammatory factors by regulating the JAK2/STAT3 signaling pathway, thereby improving lung inflammation and fibrosis.

Quercetin restores respiratory mucosal barrier dysfunction in Mycoplasma gallisepticum-infected chicks by enhancing Th2 immune response.

Mycoplasma gallisepticum (MG) has long been a pathogenic microorganism threatening the global poultry industry. Previous studies have demonstrated that the mechanism by which quercetin (QUE) inhibits the colonization of MG in chicks differs from that of antibiotics. However, the molecular mechanism by which QUE facilitates the clearance of MG remains unclear. The aim of this study was to investigate the molecular mechanism of MG clearance by QUE, with the expectation of providing new options for the treatment of MG. A model of MG infection in chicks and MG-induced M1 polarization in HD-11 cells were established. The mechanism of QUE clearance of MG was investigated by evaluating the relationship between tracheal mucosal barrier integrity, antibody levels, Th1/Th2 immune balance and macrophage metabolism and M1/M2 polarization balance. Furthermore, network pharmacology and molecular docking techniques were employed to explore the potential molecular pathways connecting QUE, M2 polarization, and fatty acid oxidation (FAO). The findings indicate that QUE remodels tracheal mucosal barrier function by regulating tight junctions and secretory immunoglobulin A (sIgA) expression levels. This process entails the regulatory function of QUE on the Th1/Th2 immune imbalance that is induced by MG infection in the tracheal mucosa. Moreover, QUE intervention impeded the M1 polarization of HD-11 cells induced by MG infection, while simultaneously promoting M2 polarization through the induction of FAO. Conversely, inhibitors of the FAO pathway impede this effect. The results of computer network analysis suggest that QUE may induce FAO via the PI3K/AKT pathway to promote M2 polarization. Notably, inhibition of the PI3K/AKT pathway was found to effectively inhibit M2 polarization in HD-11 cells, while having a limited effect on FAO. QUE promotes M2 polarization of HD-11 cells to enhance Th2 immune response through FAO and PI3K/AKT pathways, thereby restoring tracheal mucosal barrier function and ultimately inhibiting MG colonization.

Combining widely targeted metabolomics and RNA-sequencing to reveal the function analysis of Phyllanthus emblica Linn. Juice-induced poultry macrophages

This study explored the functional effects of cultivated and wild Phyllanthus emblica Linn juice (PEJ) in HD11 poultry macrophage lines, with the aim of potentially developing cultivated PE and its fruit residue as poultry feed additives. RNA-Seq was used to evaluate the functional differences between cultivated and wild PEJ induced HD11 cells. Both cultivated and wild PEJ could regulate cell replication by histone H1/H2 family genes and host immune response by Toll-like receptor 7 regulation. Wild PEJ inhibited M1-type polarization of host macrophages, while cultivated PEJ promoted M2-type polarization. Metabolites of cultivated and wild PE were identified by widely targeted metabolomics based on liquid chromatography-tandem mass spectrometry. Of the 911 metabolites, 238 differed functionally between cultivated and wild PE. The data provide a theoretical basis for the subsequent development of PE as a functional feed additive in poultry.

Characterization and functional analysis of chicken promyelocytic leukemia protein

In mammals, promyelocytic leukemia (PML) protein, also named as TRIM19, is the key component of nuclear membrane-less sub structures PML nuclear bodies (PML-NBs) or nuclear domains 10 (ND10). PML-NBs are dynamic foci that consist of numerous permanently or transiently associated proteins. The mammalian PMLs are involved in the regulation of various cellular pathways, including apoptosis, intrinsic and innate antiviral immunity, cell cycle, DNA damage, senescence and etc. Nevertheless, little is known about the role of chicken PML (chPML). In this study, chPML gene was cloned, and its several functions were characterized. We found that chPML was widely expressed in different tissues of chickens, and showed different subcellular distribution pattern in DF-1 cells comparing with LMH and HD11 cells. Like human PML, chPML was identified to be SUMOylated. K463 is one critical SUMOylation site and 240RARRG244 is SUMO interaction motif (SIM) of chPML. Moreover, qPCR showed that chPML could not only up-regulate the expression of host innate immune factor IFN-β and its downstream ISGs, but also antigen presentation-related factors including class II transactivator (CIITA) and MHC II DM beta 2 (DMB2). Notably, over-expression of chIFN-β could promote the expression of endogenous chPML. All these provide novel insights into the function of chPML, and pave the way for further studying the roles of chPML in biological process and anti-infection function.

The absence of luxS reduces the invasion of Avibacterium paragallinarum but is not essential for virulence.

The contagious respiratory pathogen, Avibacterium paragallinarum, contributes to infectious coryza in poultry. However, commercial vaccines have not shown perfect protection against infectious coryza. To search for an alternative approach, this research aimed to investigate whether the quorum-sensing system of pathogens plays a crucial role in their survival and pathogenicity. The LuxS/AI-2 quorum-sensing system in many Gram-negative and Gram-positive bacteria senses environmental changes to regulate physiological traits and virulent properties, and the role of the luxS gene in Av. paragallinarum remains unclear. To investigate the effect of the luxS gene in the quorum-sensing system of Av. paragallinarum, we constructed a luxS mutant. Bioluminescence analysis indicated that the luxS gene plays a vital role in the LuxS/AI-2 quorum-sensing system. The analysis of the LuxS/AI-2 system-related genes showed the level of pfs mRNA to be significantly increased in the mutant strain; however, lsrR, lsrK, and lsrB mRNA levels were not significantly different compared with the wild type. The ability of the luxS mutant strain to invade HD11 and DF-1 cells was significantly decreased compared with the wild-type strain. In addition, all chickens challenged with various doses of the luxS mutant strain developed infections and symptoms, and those challenged with the lowest dose exhibited only minor differences compared to chickens challenged with the wild-type strain. Thus, the deletion of the luxS gene reduces the invasion, but the luxS gene does not play an essential role in the pathogenesis of A. paragallinarum.

Alarming and calming: Dual functions of S100A9 on Mycoplasma gallisepticun infection in avian cells

Mycoplasma gallisepticum (MG) is the primary causative agent of chronic respiratory disease (CRD) in chickens, characterized by respiratory inflammation. S100A9 plays a pivotal role in modulating the inflammatory response to microbial pathogens. Our prior investigation revealed a significant upregulation of S100A9 in the lungs of chickens following MG infection. This study delves into the immunomodulatory effects of S100A9 during MG infection, demonstrating a notable increase in S100A9 levels in the lungs, immune organs, alveolar epithelial type II cells (AECII), and macrophage HD11 cells of MG-infected chicks and embryos. In MG-infected AECII cells, S100A9 overexpression significantly enhanced MG proliferation and adhesion, suppressed AVBD1, NFκB, pro-inflammatory factors (IL1β and TNFα), and chemokines, reduced apoptosis, and promoted cell proliferation, thereby facilitating MG infection. Conversely, inhibiting S100A9 produced opposing effects. In MG-infected HD11 cells, S100A9 impeded MG proliferation and adhesion, increased AVBD1, NFκB, pro-inflammatory factors, and chemokines, and induced cell apoptosis while inhibiting proliferation. Additional results demonstrated that S100A9 facilitates MG infection by modulating the TLR7/NFκB/JAK/STAT pathway in AECII/HD11 cells. In summary, S100A9 exhibits a dual role in activating/inhibiting the natural immune response through TLR7/NFκB/JAK/STAT pathway regulation. This dual role promotes MG infection in AECII cells while enabling MG to evade immune surveillance by HD11 cells, ultimately enhancing the overall infection process. These findings advance our understanding of host-pathogen interactions during MG infection and underscore S100A9's potential as a therapeutic target for CRD in chickens.

Avian Coronavirus Infectious Bronchitis Virus Activates Mitochondria-Mediated Apoptosis Pathway and Affects Viral Replication by Inducing Reactive Oxygen Species Production in Chicken HD11 Cells.

Infectious bronchitis virus (IBV), a coronavirus that causes severe respiratory and gastrointestinal illness in poultry, leads to substantial economic losses. According to earlier research, IBV infection causes chicken macrophage HD11 cells to undergo cell apoptosis. Reactive oxygen species (ROS) and the IBV-activated intrinsic apoptotic signaling pathway were examined in this work. The findings demonstrate that IBV infection causes ROS to accumulate. Moreover, IBV infection decreased the mitochondrial transmembrane potential in HD11 cells, which could be blocked by ROS antioxidants (PDTC and NAC). The two antioxidants significantly affected the expression of Bcl-2 and Bax and further inhibited the activation of caspase-3 and apoptosis in HD11 cells. Additionally, IBV replication was decreased by blocking ROS accumulation. Pretreating HD11 cells with ammonium chloride (NH4Cl) prevented IBV from entering the cells and reduced the oxidative stress which IBV causes. The ability to accumulate ROS was also lost in UV-inactivated IBV. The IBV N protein induces cell apoptosis through the activation of ROS. These findings provide an explanation for the processes of IBV infection in immune cells by indicating that IBV-induced ROS generation triggers cell apoptosis in HD11 cells.

The Functional Mechanism of BP9 in Promoting B Cell Differentiation and Inducing Antigen Presentation.

The Bursa of Fabricius, an avian unique humoral immune organ, is instrumental to B cell development. Bursal-derived peptide BP9 fosters B-cell development and formation. Yet, the exact mechanism wherein BP9 impacts B cell differentiation and antigenic presentation remains undefined. In this paper, B cell activation and differentiation in the spleen cells from mice immunized with the AIV vaccine and BP9 were detected following flow cytometry (FCM) analysis. Furthermore, the molecular mechanism of BP9 in B cell differentiation in vivo was investigated with RNA sequencing technology. To verify the potential functional mechanism of BP9 in the antigenic presentation process, the transcriptome molecular basis of chicken macrophages stimulated by BP9 was measured via high-throughput sequencing technology. The results proved that when given in experimental dosages, BP9 notably accelerated total B cells, and enhanced B-cell differentiation and plasma cell production. The gene expression profiles of B cells from mice immunized with 0.01 mg/mL BP9 and AIV vaccine disclosed that 0.01 mg/mL BP9 initiated the enrichment of several biological functions and significantly stimulated key B-cell pathways in immunized mice. Crucially, a total of 4093 differentially expressed genes were identified in B cells with BP9 stimulation, including 943 upregulated genes and 3150 downregulated genes. Additionally, BP9 induced various cytokine productions in the chicken macrophage HD11 cells and activated 9 upregulated and 20 downregulated differential miRNAs, which were involved in various signal and biological processes. Furthermore, BP9 stimulated the activation of multiple transcription factors in HD11 cells, which was related to antigen presentation processes. In summary, these results suggested that BP9 might promote B cell differentiation and induce antigen presentation, which might provide the valuable insights into the mechanism of B cell differentiation upon bursal-derived immunomodulating peptide stimulation and provide a solid experimental groundwork for enhancing vaccine-induced immunity.

Glycerol monolaurate regulates apoptosis and inflammation by suppressing lipopolysaccharide-induced ROS production and NF-κB activation in avian macrophages

Macrophages play a crucial role in both innate and adaptive immunity. However, their abnormal activation can lead to undesirable inflammatory reactions. This study aimed to investigate the effects of glycerol monolaurate (GML), a natural monoester known for its anti-inflammatory and immunoregulatory properties, on avian macrophages using the HD11 cell line. The results indicated that a concentration of 10 μg/mL of GML enhanced the phagocytic activity of HD11 cells (P < 0.05) without affecting cell viability (P > 0.05). GML decreased the expression of M1 macrophage polarization markers, such as CD86 and TNF-α genes (P < 0.05), while increasing the expression of M2 macrophage polarization markers, such as TGF-β1 and IL-10 genes (P < 0.05). GML suppressed ROS production, apoptosis, and the expression of proinflammatory genes (IL-1β and IL-6) induced by LPS (P < 0.05). GML also promoted the expression of TGF-β1 and IL-10 (P < 0.05), both in the presence and absence of LPS exposure. Moreover, GML suppressed the gene expression of TLR4 and NF-κB p65 induced by LPS (P < 0.05), as well as the phosphorylation of NF-κB p65 (P < 0.05). In conclusion, GML exhibited regulatory effects on the polarized state of avian macrophages and demonstrated significant anti-apoptotic and anti-inflammatory properties by suppressing intracellular ROS and the NF-κB signaling pathway.

Differential detection of chicken heterodimeric cytokines, interleukin 12 and 23 using their subunit-specific mouse monoclonal antibodies

Interleukin-23 (IL-23) is a recently identified member of the IL-12 family of heterodimeric cytokines that play a critical role in regulating T helper cell function. IL-12 and IL-23 share a common p40 subunit, but differ in their p35 and p19 subunits, respectively. This difference in subunit composition results in distinct signaling pathways and biological functions for IL-12 and IL-23. Here, we report the functional characterization and immunomodulatory properties of chicken IL-12 and IL-23 using the panels of newly developed mouse anti-IL-12p40, IL-12p35-α and IL-23p19 monoclonal antibodies (mAbs). Western blot and indirect ELISA analysis demonstrated that the anti-chicken IL-12p40 mAbs (chIL-12p40; #10G10F4 and #10D8G2) bound to both recombinant proteins (IL-12 and IL-23), the anti-chicken IL-12p35 mAb (chIL-12p35; #2F1) specifically recognized recombinant IL-12, and the anti-chicken IL-23p19 mAb (chIL-23p19; #15A3) exhibited specificity for recombinant IL-23, without any cross-reactivity. Two ELISAs detecting specific chicken IL-12 (#10G10F4 and #2F1) or IL-23 (#10D8G2 and #15A3) were developed using newly developed mAb combinations, #10G10F4/ #2F1 and #10D8G2/#15A3 for IL-12 and IL-23, respectively, identified through a pairing assay. The levels of IL-12 and IL-23 in Resiquimod-848 stimulated-HD11 chicken macrophage cells were monitored over time using antigen-capture sandwich ELISA developed in this study. Furthermore, the levels of chicken IL-12 and IL-23 in the circulation of Eimeria maxima (E. maxima) and Eimeria tenella (E. tenella)-infected chickens were determined. Notably, the anti-chIL-12p40 mAbs (#10G10F4 and #10D8G2) neutralized the function of both chIL-12 and chIL-23 proteins, which share the p40 subunit, while the anti-chIL-23p19 mAb (#15A3) specifically neutralized chIL-23 protein in HD11 cells in vitro. The anti-chIL-12p35 mAb (#2F1), which is specific to the p35 subunit of IL-12, showed a partial neutralizing effect on chIL-12 protein. Collectively, our study validates the specificity and significance of 2 newly developed antigen-capture immunoassays for chIL-12 and chIL-23 which will expand our understanding of the functional characteristics of IL-12 and IL-23 and their association in normal and diseased chickens. These mAbs for each subunit, anti-chIL-12p35, anti-chIL-12p40 and anti-chIL-23p19, will serve as valuable immune reagents to elucidate host immune responses against disease pathogenesis in both fundamental and applied studies of avian species.

Gentamicin Susceptibility and Comparison of Adhesion and Invasion of Caco-2 and HD11 Cell Lines by Salmonella enterica Serotypes

Foodborne Salmonella serovars are important facultative intracellular pathogens that cause gastroenteritis in humans. Four strains from three of the more predominant Salmonella serovars in poultry were studied: Typhimurium, Enteritidis, and Heidelberg. Gentamicin susceptibility was determined using an agar disc diffusion test and minimum inhibitory concentration (MIC) assays for S. Typhimurium ATCC 14028 and S. Heidelberg ARI-14. Both strains were susceptible to gentamicin in disc diffusion. The MIC of gentamicin was approximately 125 mg/ml for all strains tested. These strains’ adhesion and invasion abilities were determined with two different cell lines, a human intestinal epithelial cell line (Caco-2) as well as a chicken macrophage cell line (HD11). Attachment percentages for each Salmonella strain were greater than the strain’s ability to invade cells. Similar attachment percentages to Caco-2 cells were observed for S. Typhimurium and S. Heidelberg. Attachment percentages were lower in HD11 cells than in Caco-2 cells, although Salmonella exhibited higher apparent HD11 invasion, likely from HD11 phagocytosis. Salmonella Enteritidis showed lower rates of adhesion and invasion in HD11 cells compared to Salmonella Typhimurium. Developing a better understanding of Salmonella virulence mechanisms is critical to reducing Salmonella infections.

Synergy of Subgroup J Avian Leukosis Virus and Chicken Infectious Anemia Virus Enhances the Pathogenicity in Chickens.

Subgroup J avian leukemia virus (ALV-J) and chicken infectious anemia virus (CIAV) are widely acknowledged as significant immunosuppressive pathogens that commonly co-infect chickens, causing substantial economic losses in the poultry industry. However, whether co-infection of ALV-J and CIAV have synergistic pathogenicity remains uncertain. To explore their synergistic pathogenesis, we established a co-infection model of ALV-J and CIAV in HD11 cells and specific-pathogen-free (SPF) chickens. We discovered that ALV-J and CIAV can synergistically promote the secretion of IL-6, IL-10, IFN-α, and IFN-γ and apoptosis in HD11 cells. In vivo, compared to the ALV-J and CIAV mono-infected group, the mortality increased significantly by 27% (20 to 47%) and 14% (33 to 47%) in the co-infected group, respectively. We also discovered that ALV-J and CIAV synergistically inhibited weight gain and exhibited more severe organ damage in co-infected chickens. Furthermore, we found that CIAV can promote the replication of ALV-J in HD11 cells and significantly enhance ALV-J viral load in blood and tissues of co-infected chickens, but ALV-J cannot promote the replication of CIAV. Moreover, by measuring the immune organ indexes and proportions of blood CD3+CD4+ and CD3+CD8+ lymphocytes, more serious instances of immunosuppression were observed in ALV-J and CIAV co-infected chickens than in mono-infected chickens. Taken together, our findings demonstrate that ALV-J and CIAV synergistically enhance pathogenicity and immunosuppression.

Effects of immunosuppression-associated gga-miR-146a-5p on immune regulation in chicken macrophages by targeting the IRKA2 gene

Stress-induced immunosuppression (SIIS) is one of the common problems in intensive poultry production, which brings enormous economic losses to the poultry industry. Accumulating evidence has shown that microRNAs (miRNAs) were important regulators of gene expression in the immune system. However, the miRNA-mediated molecular mechanisms underlying SIIS in chickens are still poorly understood. This study aimed to investigate the biological functions and regulatory mechanism of miRNAs in chicken SIIS. A stress-induced immunosuppression model was successfully established via daily injection of dexamethasone and analyzed miRNA expression in spleen. Seventy-four differentially expressed miRNAs (DEMs) was identified, and 229 target genes of the DEMs were predicted. Functional enrichment analysis the target genes revealed pathways related to immunity, such as MAPK signaling pathway and FoxO signaling pathway. The candidate miRNA, gga-miR-146a-5p, was found to be significantly downregulated in the Dex-induced chicken spleen, and we found that Dex stimulation significantly inhibited the expression of gga-miR-146a-5p in Chicken macrophages (HD11). Flow cytometry, 5-ethynyl-2′-deoxyuridine (EdU), cell counting kit-8 (CCK-8) and other assays indicated that gga-miR-146a-5p can promote the proliferation and inhibit apoptosis of HD11 cells. A dual-luciferase reporter assay suggested that the Interleukin 1 receptor associated kinase 2 (IRAK2) gene, which encoded a transcriptional factor, was a direct target of gga-miR-146a-5p, gga-miR-146a-5p suppressed the post-transcriptional activity of IRAK2. These findings not only improve our understanding of the specific functions of miRNAs in avian stress but also provide potential targets for genetic improvement of stress resistance in poultry.

Unmasking the dynamics of Mycoplasma gallisepticum: deciphering HD11 macrophage polarization for innovative infection control strategies

Mycoplasma gallisepticum (MG) is a highly contagious avian respiratory pathogen characterized by rapid spread, widespread distribution, and long-term persistence of infection. Previous studies have shown that chicken macrophage HD11 cells play a critical role in the replication and immunomodulation of MG. Macrophages are multifunctional immunomodulatory cells that polarize into different functions and morphologies in response to exogenous stimuli. However, the effect of MG infection on HD11 polarization is not well understood. In this study, we observed a time-dependent increase in both the expression of the MG-related virulence protein pMGA1.2 and the copy number of MG upon MG infection. Polarization studies revealed an upregulation of M1-type marker genes in MG-infected HD11 cells, suggesting that MG mainly induces HD11 macrophages towards M1-type polarization. Furthermore, MG activated the inflammatory vesicle NLRP3 signaling pathway, and NLRP3 inhibitors affected the expression of M1 and M2 marker genes, indicating the crucial regulatory role of the NLRP3 signaling pathway in MG-induced polarization of HD11 macrophages. Our findings reveal a novel mechanism of MG infection, namely the polarization of MG-infected HD11 macrophages. This discovery suggests that altering the macrophage phenotype to inhibit MG infection may be an effective control strategy. These findings provide new perspectives on the pathogenic mechanism and control measures of MG.

Two intestinal microbiota-derived metabolites, deoxycholic acid and butyrate, synergize to enhance host defense peptide synthesis and alleviate necrotic enteritis

BackgroundNecrotic enteritis (NE) is a major enteric disease in poultry, yet effective mitigation strategies remain elusive. Deoxycholic acid (DCA) and butyrate, two major metabolites derived from the intestinal microbiota, have independently been shown to induce host defense peptide (HDP) synthesis. However, the potential synergy between these two compounds remains unexplored.MethodsTo investigate the possible synergistic effect between DCA and butyrate in regulating HDP synthesis and barrier function, we treated chicken HD11 macrophage cells and jejunal explants with DCA and sodium butyrate (NaB), either individually or in combination, for 24 h. Subsequently, we performed RNA isolation and reverse transcription-quantitative PCR to analyze HDP genes as well as the major genes associated with barrier function. To further determine the synergy between DCA and NaB in enhancing NE resistance, we conducted two independent trials with Cobb broiler chicks. In each trial, the diet was supplemented with DCA or NaB on the day-of-hatch, followed by NE induction through sequential challenges with Eimeria maxima and Clostridium perfringens on d 10 and 14, respectively. We recorded animal mortality after infection and assessed intestinal lesions on d 17. The impact of DCA and NaB on the microbiota in the ileum and cecum was evaluated through bacterial 16S rRNA gene sequencing.ResultsWe found that the combination of DCA and NaB synergistically induced multiple HDP genes in both chicken HD11 cells and jejunal explants. Additionally, the gene for claudin-1, a major tight junction protein, also exhibited synergistic induction in response to DCA and NaB. Furthermore, dietary supplementation with a combination of 0.75 g/kg DCA and 1 g/kg NaB led to a significant improvement in animal survival and a reduction in intestinal lesions compared to either compound alone in a chicken model of NE. Notably, the cecal microbiota of NE-infected chickens showed a marked decrease in SCFA-producing bacteria such as Bacteroides, Faecalibacterium, and Cuneatibacter, with lactobacilli becoming the most dominant species. However, supplementation with DCA and NaB largely restored the intestinal microbiota to healthy levels.ConclusionsDCA synergizes with NaB to induce HDP and claudin-1 expression and enhance NE resistance, with potential for further development as cost-effective antibiotic alternatives.

H9N2 Avian Influenza Virus Downregulates FcRY Expression in Chicken Macrophage Cell Line HD11 by Activating the JNK MAPK Pathway.

The H9N2 avian influenza virus causes reduced production performance and immunosuppression in chickens. The chicken yolk sac immunoglobulins (IgY) receptor (FcRY) transports from the yolk into the embryo, providing offspring with passive immunity to infection against common poultry pathogens. FcRY is expressed in many tissues/organs of the chicken; however, there are no reports investigating FcRY expression in chicken macrophage cells, and how H9N2-infected HD11 cells (a chicken macrophage-like cell line) regulate FcRY expression remains uninvestigated. This study used the H9N2 virus as a model pathogen to explore the regulation of FcRY expression in avian macrophages. FcRY was highly expressed in HD11 cells, as shown by reverse transcription polymerase chain reactions, and indirect immunofluorescence indicated that FcRY was widely expressed in HD11 cells. HD11 cells infected with live H9N2 virus exhibited downregulated FcRY expression. Transfection of eukaryotic expression plasmids encoding each viral protein of H9N2 into HD11 cells revealed that nonstructural protein (NS1) and matrix protein (M1) downregulated FcRY expression. In addition, the use of a c-jun N-terminal kinase (JNK) activator inhibited the expression of FcRY, while a JNK inhibitor antagonized the downregulation of FcRY expression by live H9N2 virus, NS1 and M1 proteins. Finally, a dual luciferase reporter system showed that both the M1 protein and the transcription factor c-jun inhibited FcRY expression at the transcriptional level. Taken together, the transcription factor c-jun was a negative regulator of FcRY, while the live H9N2 virus, NS1, and M1 proteins downregulated the FcRY expression through activating the JNK signaling pathway. This provides an experimental basis for a novel mechanism of immunosuppression in the H9N2 avian influenza virus.

Salmonella typhimurium Vaccine Candidate Delivering Infectious Bronchitis Virus S1 Protein to Induce Protection.

Infectious bronchitis (IB) is a highly infectious viral disease of chickens which causes significant economic losses in the poultry industry worldwide. An effective vaccine against IB is urgently needed to provide both biosafety and high-efficiency immune protection. In this study, the S1 protein of the infectious bronchitis virus was delivered by a recombinant attenuated Salmonella typhimurium vector to form the vaccine candidate χ11246(pYA4545-S1). S. typhimurium χ11246 carried a sifA- mutation with regulated delayed systems, striking a balance between host safety and immunogenicity. Here, we demonstrated that S1 protein is highly expressed in HD11 cells. Immunization with χ11246(pYA4545-S1) induced the production of antibody and cytokine, leading to an effective immune response against IB. Oral immunization with χ11246(pYA4545-S1) provided 72%, 56%, and 56% protection in the lacrimal gland, trachea, and cloaca against infectious bronchitis virus infection, respectively. Furthermore, it significantly reduced histopathological lesions in chickens. Together, this study provides a new idea for the prevention of IB.

Comparative study of Eimeria tenella development in different cell culture systems.

Cell culture systems have long been recognised as great resources to mitigate the use of animals in research, offering effective solutions for replacement or reduction with benefits commonly including lower costs, shorter duration and improved reproducibility. The use of in vitro culture methods has been extensively explored for many apicomplexan parasites, supporting significant research advances, but studies with Eimeria are often limited since they still depend on the animal host. In this study we have used 2.5D and 3D culture systems for the first time to evaluate the growth of Eimeria tenella parasites using a panel of cell lines (MDBK, HD11, COLO-680N and HCC4006). Results were compared to growth in 2D monolayers following established protocols. Observations using the fluorescent transgenic strain Et-dYFP showed invasion and development of parasites inside cells suspended in a collagen matrix (2.5D or 3D), supporting the development of asexual stages with the release of first-generation merozoites. Similar findings were observed when Scaffold-free 3D cell spheroids of HD11 cells were infected with sporozoites. No subsequent developmental stages were identified while evaluating these cell lines and further work will be required to improve in vitro culture systems to a point where reduction and replacement of animal use becomes routine.

IFN-γ inhibitory molecules derived from Eimeria maxima inhibit IL-12 secretion by modulating MAPK pathways in chicken macrophages

IFN-γ plays a crucial role in resisting intracellular parasitic protozoa, such as Eimeria species. In our previous study, we identified 4 molecules derived from Eimeria maxima (E. maxima) that significantly inhibited IFN-γ production. However, the mechanism underlying this inhibitory effect remains unknown. In this study, we first investigated the effects of these 4 IFN-γ inhibitory molecules on the expression levels of chicken Toll-like receptors (chTLRs), IL-12, IL-10, TGF-β, and TNF-α in chicken macrophage HD11 and bone marrow-derived dendritic cells (BMDCs). The results demonstrated that these 4 inhibitory molecules significantly downregulated the mRNA levels of chTLR-2, chTLR-4, chTLR-21, and both mRNA and protein levels of IL-12. Subsequently, to clarify the effects of these 4 inhibitory molecules on the IL-12 secretion-related signaling pathways in chicken macrophages, qRT-PCR and Western blot were used to detect the changes of key molecules involved in the signaling pathways of IL-12 secretion (NF-κB, ERK1/2, p38, JNK, STAT3) following coincubation with these inhibitory molecules. Finally, RNAi was employed to verify the function of key molecules in the signaling pathway. The results revealed a significant upregulation in the expression of ERK1/2 phosphorylated protein induced by the 4 inhibitory molecules. Knockdown of the ERK1/2 gene significantly reduced the inhibitory effect of the 4 E. maxima inhibitory molecules on IL-12. These findings indicate that the 4 inhibitory molecules can inhibit the secretion of IL-12 by upregulating the expression of ERK1/2 phosphorylated protein, which is a key molecule in the ERK-MAPK pathway. Our study may contribute to elucidating the mechanisms underlying immune evasion during E. maxima infections, thereby providing new insights for the control of chicken coccidiosis.