Interleukin-34 Regulates Th1 and Th17 Cytokine Production by Activating Multiple Signaling Pathways through CSF-1R in Chicken Cell Lines

Evolution of developmental and comparative immunology in poultry: The regulators and the regulated

Avian has a unique immune system that evolved in response to environmental pressures in all aspects of innate and adaptive immune responses, including localized and circulating lymphocytes, diversity of immunoglobulin repertoire, and various cytokines and chemokines. All of these attributes make birds an indispensable vertebrate model for studying the fundamental immunological concepts and comparative immunology. However, research on the immune system in birds lags far behind that of humans, mice, and other agricultural animal species, and limited immune tools have hindered the adequate application of birds as disease models for mammalian systems. An in-depth understanding of the avian immune system relies on the detailed studies of various regulated and regulatory mediators, such as cell surface antigens, cytokines, and chemokines. Here, we review current knowledge centered on the roles of avian cell surface antigens, cytokines, chemokines, and beyond. Moreover, we provide an update on recent progress in this rapidly developing field of study with respect to the availability of immune reagents that will facilitate the study of regulatory and regulated components of poultry immunity. The new information on avian immunity and available immune tools will benefit avian researchers and evolutionary biologists in conducting fundamental and applied research.

miRNA expression profiles of the perilesional skin of atopic dermatitis and psoriasis patients are highly similar

Atopic dermatitis (AD) and psoriasis vulgaris (PV) are chronic inflammatory skin diseases with heterogeneous molecular backgrounds. MicroRNAs (miRNAs) contribute to either development or regulation of many immune system related diseases. Only few miRNA profiling studies are available for AD and no comparisons between AD and PV skin miRNA profiles have been performed recently. We conducted a miRNA profiling analysis of skin, as well as serum, from adult AD and PV patients and control individuals. 130 miRNAs were differentially expressed in AD skin, of which 77 were common differentially expressed in AD and PV. No differentially expressed miRNAs were detected in serum. Pathway analyses revealed differentially expressed miRNAs to potentially target immune-system related pathways, including TNF-α, IL-2/STAT4 and IL-6/JAK/STAT3. Additional genetic analysis of published AD GWAS dataset detected association of several target genes of differentially expressed miRNAs in skin. Moreover, miR-28-5p, miR-31-5p, miR-378a-3p and miR-203a were validated as upregulated in the skin of AD and PV patients. All validated miRNAs were reliable predictive markers for AD or PV. In conclusion, miRNA expression pattern in the skin of adult AD patients is highly similar to that of PV with multiple differentially expressed miRNAs potentially involved in the regulation of immune responses in AD and PV.

Molecular and functional characterization of chicken interleukin 1 receptor 2 (chIL-1R2)

Interleukin-1 receptor type 2 (IL1R2) is a decoy receptor for exogenous IL-1. However, its functional role in chicken immunity is poorly understood. Herein, chicken IL-1R2 (chIL-1R2) was identified and functionally characterized in vivo and in vitro. The chIL-1R2 coding sequence includes 1,236 nucleotides encoding 412 amino acids, is highly conserved, and has a close relationship with its mammalian counterpart. Its extracellular region has three Ig-like domains but no TIR domain for intracellular signaling. Using ELISA, the recombinant chIL-1R2 protein was demonstrated to specifically bind to the chicken IL-1β. ChIL-1R2 mRNA expression was shown to be higher in the spleen, lung, kidney, small intestine, and liver. The expression of chIL-1R2 and chIL-1R1 was significantly upregulated in DF-1 cells treated with poly (I:C), but significantly downregulated in the presence of NF-κB, JNK, and MEK inhibitors, indicating that the NF-κB, JNK, and MEK signaling pathways are required for the transcriptional regulation of chIL-1R1 and chIL-1R2 expression. It is worth noting that while the p30 MAPK pathway was required for chIL-1R1 expression, it was not required for chIL-1R2 expression. Furthermore, chIL-1R2 expression increased as early as day 1, and then significantly decreased until day 3, while chIL-1R1 was dramatically upregulated in four organs of chickens infected with the highly pathogenic avian influenza virus (HPAIV). These findings indicate that chIL-1R1 and chIL-1R2 may play a crucial in innate and adaptive immune responses toward HPAIV infection. In summary the present study showed that chIL-1R2 binds to chIL-1β antibody. ChIL-1R2 expression can be induced by a viral infection, and may be regulated through NF-κB/JNK/MEK-mediated signaling pathways.

The twin cytokines interleukin-34 and CSF-1: masterful conductors of macrophage homeostasis

Macrophages are specialized cells that control tissue homeostasis. They include non-resident and tissue-resident macrophage populations which are characterized by the expression of particular cell surface markers and the secretion of molecules with a wide range of biological functions. The differentiation and polarization of macrophages relies on specific growth factors and their receptors. Macrophage-colony stimulating factor (CSF-1) and interleukine-34 (IL-34), also known as "twin" cytokines, are part of this regluatory landscape. CSF-1 and IL-34 share a common receptor, the macrophage-colony stimulating factor receptor (CSF-1R), which is activated in a similar way by both factors and turns on identical signaling pathways. However, there is some discrete differential activation leading to specific activities. In this review, we disscuss recent progress in understanding of the role of the twin cytokines in macrophage differentiation, from their interaction with CSF-1R and the activation of signaling pathways, to their implication in macrophage polarization of non-resident and tissue-resident macrophages. A special focus on IL-34, its involvement in pathophsyiological contexts, and its potential as a theranostic target for macrophage therapy will be proposed.

Molecular identification and characterisation of a novel chicken leukocyte immunoglobulin-like receptor A5

1. Leukocyte immunoglobulin-like receptor A5 (LILRA5) is a key molecule that regulates the immune system. However, the LILRA5 gene has not been characterised in avian species, including chickens. The present study aimed to identify and functionally characterise LILRA5 identified from two genetically disparate chicken lines, viz., Marek's disease (MD)-resistant (R) line 6.3 and MD-susceptible (S) line 7.2. 2. Multiple sequence alignment and phylogenetic analyses confirmed that the identity and similarity homologies of amino acids of LILRA5 in chicken lines 6.3 and 7.2 ranged between 93% and 93.7%, whereas those between chicken and mammals ranged between 20.9% and 43.7% and 21.1% to 43.9%, respectively. The newly cloned LILRA5 from chicken lines 6.3 and 7.2 revealed high conservation and a close relationship with other known mammalian LILRA5 proteins. 3. The results indicated that LILRA5 from chicken lines 6.3 and 7.2 was associated with phosphorylation of Src kinases and protein tyrosine phosphatase non-receptor type 11 (SHP2), which play a regulatory role in immune functions. Moreover, the results demonstrated that LILRA5 in these lines was associated with the activation of major histocompatibility complex (MHC) class I and β2-microglobulin and induced the expression of the transporter associated with antigen processing. In addition, LILRA5 in both chicken lines activated and induced Janus kinase (JAK)-signal transducer and the activator of transcription (STAT), nuclear factor kappa B (NF-κB), phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT) and the extracellular signal-regulated kinase (ERK)1/2 signalling pathways; toll-like receptors; and Th1-, Th2-, and Th17- cytokines. 4. The data suggested that LILRA5 has innate immune receptors essential for macrophage immune response and provide novel insights into the regulation of immunity and immunopathology.

Interleukin-dependent modulation of the expression of MHC class I and MHC class II genes in chicken HD11 cells

Interleukins (ILs) regulate cell surface antigens known as activation markers, which have distinct functional roles. However, the regulation of major histocompatibility complex (MHC) class I, MHC class II, and related genes by cytokines in chickens is not well understood. In the present study, we evaluated the influence of certain recently discovered chicken interleukins-i.e., IL-11, IL-12B, IL-17A, IL-17B, IL-26, and IL-34-on the expression and regulation of genes related to MHC class I, MHC class II, and the associated proteins in an HD11 chicken macrophage cell line. We used quantitative reverse transcription polymerase chain reaction (qRT-PCR), immunocytochemical, and flow cytometric analyses to assess dose- and time-dependent expression in the HD11 cell line and found that the ILs induced MHC class I, MHC class II, and associated protein. As NF-κB is actively involved in cell activation and is constitutively activated in many immune cells, we also determined whether NF-κB regulates MHC class I, MHC class II, and related gene expression in the HD11 cell line. The NF-κB inhibitor sulfasalazine (Sz) dose-dependently inhibited MHC class I and MHC class II in the HD11 cell line. Sz also downregulated the expression of MHC class I, MHC class II, and the associated proteins in the IL-induced HD11 cell line. The expression of MHC class I, MHC class II, and associated genes was accompanied by the Sz-sensitive degradation of the p65 (RelA) and p50 subunits of NF-κB and IκBα. Our results indicate that the different effects of each IL on the expression of genes related to MHC class I, MHC class II, and the associated proteins are involved with the regulation of the dose and duration of antigenic peptide presentation and, thus, also influence Th1, Th2, and Th17 production.

Mudskipper interleukin-34 modulates the functions of monocytes/macrophages via the colony-stimulating factor-1 receptor 1

Interleukin-34 (IL-34) is a novel cytokine that plays an important role in innate immunity and inflammatory processes by binding to the colony-stimulating factor-1 receptor (CSF-1R). However, information on the function of IL-34 in fish remains limited. In the present study, we identified an IL-34 homolog from mudskippers (Boleophthalmus pectinirostris). In silico analysis showed that the mudskipper IL-34 (BpIL-34) was similar to other known IL-34 variants in sequence and structure and was most closely related to an orange-spotted grouper (Epinephelus coioides) homolog. BpIL-34 transcripts were constitutively expressed in various tissues, with the highest level of expression found in the brain. Edwardsiella tarda infection significantly up-regulated the mRNA expression of BpIL-34 in the mudskipper tissues. The recombinant mature BpIL-34 peptide (rBpIL-34) was purified and used to produce anti-rBpIL-34 IgG. Western blot analysis combined with PNGase F digestion revealed that native BpIL-34 in monocytes/macrophages (MOs/MФs) was N-glycosylated. In vitro, rBpIL-34 treatment enhanced the phagocytotic and bactericidal activity of mudskipper MOs/MФs, as well as the mRNA expression of pro-inflammatory cytokines like tumor necrosis factor α (BpTNF-α) and BpIL-1β in these cells. Furthermore, the knockdown of mudskipper CSF-1R1 (BpCSF-1R1), but not mudskipper BpCSF-1R2, significantly inhibited the rBpIL-34-mediated enhanced effect on MO/MФ function. In conclusion, our results indicate that mudskipper BpIL-34 modulates the functions of MOs/MФs via BpCSF-1R1.

Interleukin 34 Serves as a Novel Molecular Adjuvant against Nocardia Seriolae Infection in Largemouth Bass (Micropterus Salmoides)

DNA vaccines have been widely employed in controlling viral and bacterial infections in mammals and teleost fish. Co-injection of molecular adjuvants, including chemokines, cytokines, and immune co-stimulatory molecules, is one of the potential strategies used to improve DNA vaccine efficacy. In mammals and teleost fish, interleukin-34 (IL-34) had been described as a multifunctional cytokine and its immunological role had been confirmed; however, the adjuvant capacity of IL-34 remains to be elucidated. In this study, IL-34 was identified in largemouth bass. A recombinant plasmid of IL-34 (pcIL-34) was constructed and co-administered with a DNA vaccine encoding hypoxic response protein 1 (Hrp1; pcHrp1) to evaluate the adjuvant capacity of pcIL-34 against Nocardia seriolae infection. Our results indicated that pcIL-34 co-injected with pcHrp1 not only triggered innate immunity and a specific antibody response, but also enhanced the mRNA expression level of immune-related genes encoding for cytokines, chemokines, and humoral and cell-mediated immunity. Moreover, pcIL-34 enhanced the protection of pcHrp1 against N. seriolae challenge and conferred the relative percent survival of 82.14%. Collectively, IL-34 is a promising adjuvant in a DNA vaccine against nocardiosis in fish.

Interleukin-34 mediated by hepatitis B virus X protein via CCAAT/enhancer-binding protein α contributes to the proliferation and migration of hepatoma cells

Objectives

Interleukin‐34 (IL‐34) is associated with hepatitis B virus (HBV) infection and hepatocellular carcinoma (HCC). However, the role and associated mechanisms of IL‐34 in HBV‐related HCC remain unclear. In this study, the expression, biological function and associated mechanisms of IL‐34 in HBV‐related HCC cells were investigated.

Methods

IL‐34 expression induced by HBV and HBV X (HBX) gene was measured in hepatoma cells. The role of CCAAT/enhancer‐binding protein α (CEBP/α) in HBX‐induced IL‐34 expression was examined. The signal pathways involved in the expression of CEBP/α and IL‐34 induced by HBX were assessed. The role of IL‐34 in the proliferation and migration of HCC cells, and related mechanisms were explored.

Results

Dependent on HBX, HBV increased IL‐34 expression in hepatoma cells, and HBX upregulated and interacted with CEBP/α to enhance the activity of IL‐34 promoters. CEBP/α mediated by HBX was associated with the activation of PI3‐K and NF‐κB pathways to promote IL‐34 expression. Via CSF1‐R and CD138, IL‐34 promoted the proliferation and migration of hepatoma cells, and contributed to the activation of ERK and STAT3 pathways and the upregulation of Bcl‐xl and c‐Myc mediated by HBX.

Conclusion

We demonstrate that IL‐34 contributes to HBX‐mediated functional abnormality of HCC cells and provides a novel insight into the molecular mechanism of carcinogenesis mediated by HBX.