Regulation of the IL-12/IL-12R axis: a critical step in T-helper cell differentiation and effector function

Baicalein alleviates cardiomyocyte death in EAM mice by inhibiting the JAK-STAT1/4 signalling pathway

BACKGROUND

The experimental autoimmune myocarditis (EAM) model is valuable for investigating myocarditis pathogenesis. M1-type macrophages and CD4+T cells exert key pathogenic effects on EAM initiation and progression. Baicalein (5,6,7-trihydroxyflavone, C15H10O5, BAI), which is derived from the Scutellaria baicalensis root, is a primary bioactive compound with potent anti-inflammatory and antioxidant properties. BAI exerts good therapeutic effects against various autoimmune diseases; however, its effect in EAM has not been thoroughly researched.

PURPOSE

This study aimed to explore the possible inhibitory effect of BAI on M1 macrophage polarisation and CD4+T cell differentiation into Th1 cells via modulation of the JAK-STAT1/4 signalling pathway, which reduces the secretion of pro-inflammatory factors, namely, TNF-α and IFN-γ, and consequently inhibits TNF-α- and IFN-γ-triggered apoptosis in cardiomyocytes of the EAM model mice.

STUDY DESIGN AND METHODS

Flow cytometry, immunofluorescence, real-time quantitative polymerase chain reaction (q-PCR), and western blotting were performed to determine whether BAI alleviated M1/Th1-secreted TNF-α- and IFN-γ-induced myocyte death in the EAM model mice through the inhibition of the JAK-STAT1/4 signalling pathway.

RESULTS

These results indicate that BAI intervention in mice resulted in mild inflammatory infiltrates. BAI inhibited JAK-STAT1 signalling in macrophages both in vivo and in vitro, which attenuated macrophage polarisation to the M1 type and reduced TNF-α secretion. Additionally, BAI significantly inhibited the differentiation of CD4+T cells to Th1 cells and IFN-γ secretion both in vivo and in vitro by modulating the JAK-STAT1/4 signalling pathway. This ultimately led to decreased TNF-α and IFN-γ levels in cardiac tissues and reduced myocardial cell apoptosis.

CONCLUSION

This study demonstrates that BAI alleviates M1/Th1-secreted TNF-α- and IFN-γ-induced cardiomyocyte death in EAM mice by inhibiting the JAK-STAT1/4 signalling pathway.

Nuclear factor kappa B-dependent persistence of Salmonella Typhi and Paratyphi in human macrophages

Salmonella serovars Typhi and Paratyphi cause a prolonged illness known as enteric fever, whereas other serovars cause acute gastroenteritis. Mechanisms responsible for the divergent clinical manifestations of nontyphoidal and enteric fever Salmonella infections have remained elusive. Here, we show that S. Typhi and S. Paratyphi A can persist within human macrophages, whereas S. Typhimurium rapidly induces apoptotic macrophage cell death that is dependent on Salmonella pathogenicity island 2 (SPI2). S. Typhi and S. Paratyphi A lack 12 specific SPI2 effectors with pro-apoptotic functions, including nine that target nuclear factor κB (NF-κB). Pharmacologic inhibition of NF-κB or heterologous expression of the SPI2 effectors GogA or GtgA restores apoptosis of S. Typhi-infected macrophages. In addition, the absence of the SPI2 effector SarA results in deficient signal transducer and activator of transcription 1 (STAT1) activation and interleukin 12 production, leading to impaired TH1 responses in macrophages and humanized mice. The absence of specific nontyphoidal SPI2 effectors may allow S. Typhi and S. Paratyphi A to cause chronic infections.

IMPORTANCE

Salmonella enterica is a common cause of gastrointestinal infections worldwide. The serovars Salmonella Typhi and Salmonella Paratyphi A cause a distinctive systemic illness called enteric fever, whose pathogenesis is incompletely understood. Here, we show that enteric fever Salmonella serovars lack 12 specific virulence factors possessed by nontyphoidal Salmonella serovars, which allow the enteric fever serovars to persist within human macrophages. We propose that this fundamental difference in the interaction of Salmonella with human macrophages is responsible for the chronicity of typhoid and paratyphoid fever, suggesting that targeting the nuclear factor κB (NF-κB) complex responsible for macrophage survival could facilitate the clearance of persistent bacterial infections.

Interleukin-12: Structure, Function, and Its Impact in Colorectal Cancer

Interleukin 12 (IL-12) is a heterodimer consisting of 2 subunits, p35 and p40, with unique associations and interacting functions with its family members. IL-12 is one of the most important cytokines regulating the immune system response and is integral to adaptive immunity. IL-12 has shown marked therapeutic potential in a variety of tumor types. This review therefore summarizes the characteristics of IL-12 and its application in tumor treatment, focusing on its antitumor effects in colorectal cancer (CRC) and potential radiosensitization mechanisms. We aim to provide a current reference for IL-12 and other potential CRC treatment strategies.

Interleukin 23 receptor: Expression and regulation in immune cells

The importance of IL-23 and its specific receptor, IL-23R, in the pathogenesis of several chronic inflammatory diseases has been established, but the underlying pathological mechanisms are not fully understood. This review focuses on IL-23R expression and regulation in immune cells.

An optimized IL-12-Fc expands its therapeutic window, achieving strong activity against mouse tumors at tolerable drug doses

BACKGROUND

Interleukin-12 (IL-12) has emerged as one of the most potent cytokines for tumor immunotherapy due to its ability to induce interferon γ (IFNγ) and polarize Th1 responses. Clinical use of IL-12 has been limited by a short half-life and narrow therapeutic index.

METHODS

We generated a monovalent, half-life-extended IL-12-Fc fusion protein, mDF6006, engineered to retain the high potency of native IL-12 while significantly expanding its therapeutic window. In vitro and in vivo activity of mDF6006 was tested against murine tumors. To translate our findings, we developed a fully human version of IL-12-Fc, designated DF6002, which we characterized in vitro on human cells and in vivo in cynomolgus monkeys in preparation for clinical trials.

FINDINGS

The extended half-life of mDF6006 modified the pharmacodynamic profile of IL-12 to one that was better tolerated systemically while vastly amplifying its efficacy. Mechanistically, mDF6006 led to greater and more sustained IFNγ production than recombinant IL-12 without inducing high, toxic peak serum concentrations of IFNγ. We showed that mDF6006's expanded therapeutic window allowed for potent anti-tumor activity as single agent against large immune checkpoint blockade-resistant tumors. Furthermore, the favorable benefit-risk profile of mDF6006 enabled effective combination with PD-1 blockade. Fully human DF6002, similarly, demonstrated an extended half-life and a protracted IFNγ profile in non-human primates.

CONCLUSION

An optimized IL-12-Fc fusion protein increased the therapeutic window of IL-12, enhancing anti-tumor activity without concomitantly increasing toxicity.

FUNDING

This research was funded by Dragonfly Therapeutics.

Identification of a 5-Methylcytosine Site (mC-7) That May Inhibit CXCL11 Expression and Regulate E. coli F18 Susceptibility in IPEC-J2 Cells

The primary pathogen causing post-weaning diarrhea in piglets is Escherichia coli F18 (E. coli F18), hence it is essential to investigate the mechanism governing E. coli F18 resistance in native pig breeds. Based on the previous RNA-seq results of the duodenum from E. coli F18-resistant and -susceptible Meishan piglets, CXCL11, an important functional gene, was preliminarily screened. In this investigation, in order to further examine the expression regulation mechanism of E. coli F18 in intestinal porcine epithelial cells (IPEC-J2) against E. coli F18 infection, CXCL11 gene expression on IPEC-J2 cells infected by E. coli F18 was detected, which was significantly downregulated (p < 0.01). Secondly, the overexpression on the IPEC-J2 cell line was successfully structured, and a relative quantification method of the PILIN, bacteria enumeration, and immunofluorescence assay indicated that the CXCL11 overexpression significantly reduced the ability of E. coli F18 to interact with IPEC-J2 in vitro. The promoter region of the CXCL11 gene was predicted to contain a CpG island (−619 ~ −380 bp) of which 13 CpG sites in the sequencing region were methylated to varying degrees, and the methylation level of one CPG site (mC-7) positively linked negatively with the expression of the CXCL11 gene (p < 0.05). Meanwhile, a dual luciferase assay detected the mutation of the mC-7 site that significantly inhibited the luciferase activity of the CXCL11 gene promoter (p < 0.01). Transcription factor prediction and expression verification indicated that mC-7 is located in the OSR1-binding domain, and that its expression level is related to E. coli F18 susceptibility. We speculated that methylation modification of the mC-7 site of the CpG island in the promoter region of the CXCL11 gene might inhibit the binding of transcription factor OSR1 with the mC-7 site, and then affect its expression level to regulate the susceptibility to E. coli F18.

Soluble C-Type Lectin-Receptor Ligands Stimulate ROS Production in Dendritic Cells and Potentiate Killing of MRSA as Well as the MRSA Induced IL-12 Production

Methicillin resistant Staphylococcus aureus (MRSA) has developed resistance to most β-lactam antibiotics leaving few treatment options against infections with MRSA. Through mannose receptors, mannan potentiates IL-12 production induced by Gram-positive bacteria, a cytokine crucial in the clearance of S. aureus infection. We investigated the IL-12 potentiating effect of mannan pre-treatment of bone marrow-derived dendritic cells prior to stimulation with clinical MRSA strains. Mannan almost doubled IL-12 as well as IFN-β production in response to USA300, also when USA300 was treated with the β-lactam cefoxitin. The MRSA-induced IL-12 production was dependent on bacterial uptake and reactive oxygen species (ROS). Mannan alone induced ROS production, and in combination with USA300, the ROS produced corresponded to the sum induced by mannan and USA300. Addition of a monoclonal antibody against the mannose receptor likewise enhanced USA300-induced IL-12 and induced ROS production. Mannan addition further increased the endocytosis as well as the rate of endosomal killing of bacteria. Pre-treatment with soluble β-glucans also induced ROS and potentiated the USA300-induced IL-12 indicating that other C-type receptors may play a similar role. In the presence of the pro-inflammatory mediators, GM-CSF or IFN-γ, the mannan-enhanced IL-12 production increased further. The USA300-induced and the mannan-facilitated enhanced IFN-β and IL-12 showed same dependency on MAPK c-Jun N-terminal kinase signaling, suggesting that mannan enhances the signals already induced by the bacteria, rather than changing them. We suggest that the C-type lectin-induced ROS production is a key factor in the IFN-β and IL-12 potentiation.

Cytokine Receptors-Regulators of Antimycobacterial Immune Response

Cytokine receptors are critical regulators of the antimycobacterial immune response, playing a key role in initiating and coordinating the recruitment and activation of immune cells during infection. They recognize and bind specific cytokines and are involved in inducing intracellular signal transduction pathways that regulate a diverse range of biological functions, including proliferation, differentiation, metabolism and cell growth. Due to mutations in cytokine receptor genes, defective signaling may contribute to increased susceptibility to mycobacteria, allowing the pathogens to avoid killing and immune surveillance. This paper provides an overview of cytokine receptors important for the innate and adaptive immune responses against mycobacteria and discusses the implications of receptor gene defects for the course of mycobacterial infection.

TIM-3 blockade enhances IL-12-dependent antitumor immunity by promoting CD8+ T cell and XCR1+ dendritic cell spatial co-localization

BACKGROUND

T cell immunoglobulin and mucin domain containing-3 (TIM-3) blocking antibodies are currently being evaluated in clinical trials for solid and hematological malignancies. Despite its identification on T cells, TIM-3 is predominantly expressed by myeloid cells, including XCR1+ type I conventional dendritic cells (cDC1s). We have recently shown that TIM-3 blockade promotes expression of CXCR3 chemokine ligands by tumor cDCs, but how this drives a CD8+ T cell-dependent response to therapy is unclear.

METHODS

T cell infiltration, effector function, and spatial localization in relation to XCR1+ cDC1s were evaluated in a murine orthotopic mammary carcinoma model during response to TIM-3 blockade and paclitaxel chemotherapy. Mixed bone marrow chimeras and diphtheria toxin depletion were used to determine the role of specific genes in cDC1s during therapeutic responses.

RESULTS

TIM-3 blockade increased interferon-γ expression by CD8+ T cells without altering immune infiltration. cDC1 expression of CXCL9, but not CXCL10, was required for response to TIM-3 blockade. CXCL9 was also necessary for the increased proximity observed between CD8+ T cells and XCR1+ cDC1s during therapy. Tumor responses were dependent on cDC1 expression of interleukin-12, but not MHCI.

CONCLUSIONS

TIM-3 blockade increases exposure of intratumoral CD8+ T cells to cDC1-derived cytokines, with implications for the design of therapeutic strategies using antibodies against TIM-3.

Fasciola gigantica excretory-secretory products (FgESPs) modulate the differentiation and immune functions of buffalo dendritic cells through a mechanism involving DNMT1 and TET1

Background

Fasciola gigantica infection threatens the health of both humans and animals in the world. The excretory/secretory products (ESPs) of this fluke has been reported to impair the activation and maturation of immune cells. We have previously shown the influence of F. gigantica ESPs (FgESPs) on the maturation of buffalo dendritic cells (DCs). However, the underlying mechanisms remain unclear. The objective of this study was to investigate the potency of FgESPs in shifting the differentiation and immune functions of buffalo DCs.

Methods

Buffalo DCs were incubated with FgESPs directly or further co-cultured with lymphocytes in vitro. qRT-PCR was employed to determine the gene expression profile of DCs or the mixed cells, and an ELISA was used to measure cytokine levels in the supernatants. Hoechst and Giemsa staining assays, transmission electron microscopy, caspase-3/7 activity test and histone methylation test were performed to determine DC phenotyping, apoptosis and methylation. To investigate the mechanism involved with DNA methylation, a Co-IP assay and immunofluorescent staining assay were performed to observe if there was any direct interaction between FgESPs and DNMT1/TET1 in buffalo DCs, while RNAi technology was employed to knockdown DNMT1 and TET1 in order to evaluate any different influence of FgESPs on DCs when these genes were absent.

Results

qRT-PCR and ELISA data together demonstrated the upregulation of DC2 and Th2/Treg markers in DCs alone and DCs with a mixed lymphocyte reaction (MLR), suggesting a bias of DC2 that potentially directed Th2 differentiation in vitro. DC apoptosis was also found and evidenced morphologically and biochemically, which might be a source of tolerogenic DCs that led to Treg differentiation. In addition, FgESPs induced methylation level changes of histones H3K4 and H3K9, which correlate with DNA methylation. Co-IP and immunofluorescent subcellular localization assays showed no direct interaction between the FgESPs and DNMT1/TET1 in buffalo DCs. The productions of IL-6 and IL-12 were found separately altered by the knockdown of DNMT1 and TET1 in DCs after FgESPs treatment.

Conclusions

FgESPs may induce the DC2 phenotype or the apoptosis of buffalo DCs to induce the downstream Th2/Treg response of T cells, possibly through a DNMT1- or TET1-dependent manner(s).

The IL-23/IL-17 pathway in human chronic inflammatory diseases-new insight from genetics and targeted therapies

Chronic inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease, spondyloarthritis, and psoriasis cause significant morbidity and are a considerable burden for the patients in terms of pain, impaired function, and diminished quality of life, as well as for society, because of the associated high health-care costs and loss of productivity. Our limited understanding of the pathogenic mechanisms involved in these diseases currently hinders early diagnosis and the development of more specific and effective therapies. The past years have been marked by considerable progress in our insight of the genetic basis of many diseases. In particular, genome-wide association studies (GWAS) performed with thousands of patients have provided detailed information about the genetic variants associated with a large number of chronic inflammatory diseases. These studies have brought to the forefront many genes linked to signaling pathways that were not previously known to be involved in pathogenesis, pointing to new directions in the study of disease mechanisms. GWAS also provided fundamental evidence for a key role of the immune system in the pathogenesis of these diseases, because many of the identified loci map to genes involved in different immune processes. However, the mechanisms by which disease-associated genetic variants act on disease development and the targeted cell populations remain poorly understood. The challenge of the post-GWAS era is to understand how these variants affect pathogenesis, to allow translation of genetic data into better diagnostics and innovative treatment strategies. Here, we review recent results that document the importance of the IL-23/IL-17 pathway for the pathogenesis of several chronic inflammatory diseases and summarize data that demonstrate how therapeutic targeting of this pathway can benefit affected patients.

Behçet's disease: An immunogenetic perspective

Behçet's disease (BD) is a chronic and rare multisystemic disorder defined by autoimmunity and inflammatory characteristics, manifested by ocular lesions, recurrent genital and oral ulcers, skin symptoms and arthritis as well as neurological, intestinal, and vascular involvement. Despite the unknown cause of BD, there is some strong documentation for immunological, genetic, environmental, and infectious factors playing a role in the pathogenesis of BD. While the nature of the genetic variants remains unidentified, many genetic risk factors are considered to contribute to BD susceptibility. Along with human leukocyte antigen gene encoding B*51 (HLA-B*51) and areas including the major histocompatibility complex class I, genome-wide association studies have recognized numerous other BD susceptibility genes including those encoding interleukin (IL)-10, IL-12 receptor β 2 (IL-12RB2), IL-23 receptor (IL-23R), C-C chemokine receptor 1 gene, signal transducer and activator of transcription 4 (STAT4), endoplasmic reticulum aminopeptidase (ERAP1), and genes encoding killer cell lectin-like receptor family members (KLRC4-KLRK1). It is believed that BD could be considered as a disorder lying in between autoimmune and autoinflammatory syndromes. The positive responses to classical immunosuppressive agents like azathioprine and cyclosporine and involvement of autoantigens in the initiation of the disorder are the main BD features that reflect the autoimmune nature of the disorder. In this review, we address recent findings on the role of common cytokines, antibodies and immunogenetic factors in BD.

Immunological, anti-angiogenic and clinical effects of intratumoral interleukin 12 electrogene therapy combined with metronomic cyclophosphamide in dogs with spontaneous cancer: A pilot study

The immunological, anti-angiogenic and clinical effects of metronomic cyclophosphamide and 3 consecutive intratumoral interleukin (IL)-12 gene therapy (electrogene therapy (EGT)) treatments were evaluated in 6 dogs with spontaneous cancer. In all dogs, a decrease in peripheral leukocytes 2 days after IL-12 EGT coincided with erythema and swelling of the tumor. In the tumor, a transient increase in IL-12 levels was measured, whereas a continuous increase in interferon γ (IFNγ) and thrombospondin 1 (TSP-1) were determined in contrast to a continuous decrease in vascular endothelial growth factor (VEGF). In the serum, a transient increase in IL-12 and IL-10 levels were noted in contrast to a transient decrease in VEGF and TSP-1. The treatment resulted in a significant anti-angiogenic effect. Although all primary tumors continued to progress in time, this progression was slower than before treatment according to the contrast-enhanced ultrasound data. Besides the encouraging immunostimulatory and anti-angiogenic effects observed in all dogs we also noticed in 4 out of 6 dogs clinically relevant improvements in quality of life and weight. These results hold great promise for combinatorial strategies of IL-12 EGT and metronomic chemotherapy with conventional antitumor (immuno)therapies.

The influence of sex hormones on cytokines in multiple sclerosis and experimental autoimmune encephalomyelitis: a review

The female predominance of multiple sclerosis (MS) has suggested that hormonal differences between the sexes must confer some protective effect on males or enhance the susceptibility of females to this disease. There has been evidence that gonadal hormones can modulate the immune response regulated by antigen presenting cells and T cells. These cells control the immune response by the production of interacting pro- and anti-inflammatory cytokines. The first include the acute phase pro-inflammatory cytokines of the innate immune response as well as the T-helper 1 (Th1) cytokines, while the later contain the Th2 cytokines as well as the suppressor cytokines. There is some evidence that MS and experimental autoimmune encephalitis (EAE) are Th1 cell-mediated diseases. For this reason many studies have been done to influence the pro-inflammatory cytokine production of these Th1 cells in favour of an anti-inflammatory immune response as mediated by Th2 cells. However the role of the regulatory T cells in this context is not clearly understood. Here we review the studies concerning the role of sex hormones on the cytokine production in relation to the disease course of MS and EAE and in particular in the light of the recent revival of the regulatory T cells and their suppressive cytokines.

Immunopathological assessments of human Blastocystis spp. in experimentally infected immunocompetent and immunosuppresed mice

Blastocystis spp., one of the most common parasites colonizing the human intestine, is an extracellular, luminal protozoan with controversial pathogenesis. The host's immune response against Blastocystis spp. infection has also not been defined yet. Therefore, this research aimed to assess the potential pathogenicity of this parasite and its ability to modulate the immune response in experimental infected immunocompetent and immunosuppresed mice. These results demonstrated that the infected immunosuppressed mice were more affected than infected immunocompetent mice. Histopathological examination of the small intestine in the infected immunosuppressed mice showed that Blastocystis spp. infiltrated all the layers. Moreover, the epithelia showed exfoliation and inflammatory cell infiltration in submucosa compared to that of the infected immunocompetent mice. As well, examination of the large intestine of the infected immunosuppressed group showed severe goblet cell hyperplasia. Blastocystis spp. infiltrated all the large intestine layers compared to that of the infected immunocompetent group. Furthermore, there was a significant upregulation of the expression of proinflammatory cytokines: interleukin 12 (IL-12) and tumor necrosis factor alpha (TNF-α) in the infected immunosuppressed mice compared to that of the infected immunocompetent ones (p ≤ 0.004 and p ≤ 0.002, respectively). However, the expression of anti-inflammatory cytokines (IL-4 and IL-10) was significantly downregulated in the infected immunosuppressed group compared to that of the infected immunocompetent group one at 10 days postinfection (p ≤ 0.002 and p ≤ 0.001, respectively). The results of this study revealed that Blastocystis spp. affected the production of pro- and anti-inflammatory cytokines in both groups of mice compared to healthy normal (naive) group. Additionally, these data showed that there was a significant upregulation (p ≤ 0.005) of the locally synthesized antibody: secretary IgA (sIgA) in the gut of the infected immunocompetent mice when compared to that of the infected immunosuppressed ones.

Investigation of cytokines, oxidative stress, metabolic, and inflammatory biomarkers after orange juice consumption by normal and overweight subjects

Background

Abdominal adiposity has been linked to metabolic abnormalities, including dyslipidemia, oxidative stress, and low-grade inflammation.

Objective

To test the hypothesis that consumption of 100% orange juice (OJ) would improve metabolic, oxidative, and inflammatory biomarkers and cytokine levels in normal and overweight subjects with increased waist circumference.

Design

Subjects were divided into two groups in accordance with their body mass index: normal and overweight. Both groups of individuals consumed 750 mL of OJ daily for 8 weeks. Body composition (weight, height, percentage of fat mass, and waist circumference); metabolic biomarkers (total cholesterol, low-density lipoprotein-cholesterol [LDL-C], high-density lipoprotein-cholesterol [HDL-C], triglycerides, glucose, insulin, HOMA-IR, and glycated hemoglobin); oxidative biomarkers (malondialdehyde and DPPH^•); inflammatory biomarkers (high-sensitivity C-reactive protein [hsCRP]); cytokines (IL-4, IL-10, IL-12, TNF-α, and IFN-γ); and diet were evaluated before and after consumption of OJ for 8 weeks.

Results

The major findings of this study were: 1) no alteration in body composition in either group; 2) improvement of the lipid profile, evidenced by a reduction in total cholesterol and LDL-C; 3) a potential stimulation of the immune response due to increase in IL-12; 4) anti-inflammatory effect as a result of a marked reduction in hsCRP; and 5) antioxidant action by the enhancement of total antioxidant capacity and the reduction of lipid peroxidation, in both normal and overweight subjects.

Conclusions

OJ consumption has a positive effect on important biomarkers of health status in normal and overweight subjects, thereby supporting evidence that OJ acts as functional food and could be consumed as part of a healthy diet to prevent metabolic and chronic diseases.

The potential of interleukin 12 receptor beta 2 (IL12RB2) and tumor necrosis factor receptor superfamily member 8 (TNFRSF8) gene as diagnostic biomarkers of oral lichen planus (OLP)

OBJECTIVE

This study evaluated the potential of interleukin 12 receptor beta 2 and tumor necrosis factor receptor superfamily member 8 as diagnostic biomarkers of oral lichen planus (OLP).

MATERIALS AND METHODS

The mRNA expression of IL12RB2 and TNFRSF8 in FFPE OLP samples (OLP group, n = 38) were investigated with quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) analysis and compared to those of chronic non-specific mucositis (Non-OLP group, n = 25) and normal mucosa (Normal group, n = 18). Predictive modeling of the expression of IL12RB2 and TNFRSF8 was constructed using support vector machine (SVM), random forest (RF), linear discriminant analysis (LDA), neural network (NN) and naive Bayes (NB) methods.

RESULTS

Normalized expression of IL12RB2 in the OLP group (3.78 ± 1.67) was significantly higher than the Normal group (1.97 ± 1.12), but lower than the Non-OLP group (6.86 ± 1.67). TNFRSF8 gene expression in the OLP group (7.46 ± 1.51) was significantly higher than the Normal group (2.90 ± 1.61), but no significant difference was found between the OLP and Non-OLP groups. The ratio of IL12RB2/TNFRSF8 in the OLP group (0.52 ± 0.23) was significantly lower than the Normal group (0.74 ± 0.39) and the Non-OLP group (1.07 ± 0.38). In the predictive modeling, the area under receiver operating characteristic (ROC) curves (AUC) ranged from 0.83-0.92 and their accuracy was higher than 0.75 in all methods.

CONCLUSIONS

The IL12RB2/TNFRSF8 ratio can be a useful diagnostic tool for OLP.

Signal transducer and activator of transcription 4 in liver diseases

STAT4 is a member of the signal transducer and activator of transcription (STAT) family of molecules that localizes to the cytoplasm. STAT4 regulates various genes expression as a transcription factor after it is phosphorylated, dimerizes and translocates to the nucleus. STAT4 activation is detected virtually in the liver of several mouse models of liver injury, as well as the human liver of chronic liver diseases. STAT4 gene polymorphism has been shown to be associated with the antiviral response in chronic hepatitis C and drug-induced liver injury (DILI), primary biliary cirrhosis (PBC), HCV-associated liver fibrosis and in hepatocellular carcinoma (HCC). However, the roles of STAT4 in the pathogeneses of liver diseases are still not understood entirely. This review summarizes the recent advances on the functional roles of STAT4 and its related cytokines in liver diseases, especially in regulating hepatic anti-viral responses, inflammation, proliferation, apoptosis and tumorigenesis. Targeting STAT4 signaling pathway might be a promising strategy in developing therapeutic approaches for treating hepatitis in order to prevent further injury like cirrhosis and liver cancer.

Cysticerci drive dendritic cells to promote in vitro and in vivo Tregs differentiation

Regulatory T cells (Tregs) play a crucial role in immune homeostasis. Treg induction is a strategy that parasites have evolved to modulate the host's inflammatory environment, facilitating their establishment and permanence. In human Taenia solium neurocysticercosis (NC), the concurrence of increased peripheral and central Treg levels and their capacity to inhibit T cell activation and proliferation support their role in controlling neuroinflammation. This study is aimed at identifing possible mechanisms of Treg induction in human NC. Monocyte-derived dendritic cells (DC) from healthy human donors, cocultivated with autologous CD4⁺ naïve cells either in the presence or absence of cysticerci, promoted CD25^highFoxp3+ Treg differentiation. An increased Treg induction was observed when cysticerci were present. Moreover, an augmentation of suppressive-related molecules (SLAMF1, B7-H1, and CD205) was found in parasite-induced DC differentiation. Increased Tregs and a higher in vivo DC expression of the regulatory molecules SLAMF1 and CD205 in NC patients were also found. SLAMF1 gene was downregulated in NC patients with extraparenchymal cysticerci, exhibiting higher inflammation levels than patients with parenchymal parasites. Our findings suggest that cysticerci may modulate DC to favor a suppressive environment, which may help parasite establishment, minimizing the excessive inflammation, which may lead to tissue damage.

IL-12Rβ2 is critical for survival of primary Francisella tularensis LVS infection

Using a panel of vaccines that provided different degrees of protection, we previously identified the IL-12 receptor subunit β2 as a mediator, whose relative expression correlated with strength of protection against secondary lethal challenge of vaccinated mice with an intracellular bacterium, the LVS of Francisella tularensis. The present study therefore tested the hypothesis that IL-12Rβ2 is an important mediator in resistance to LVS by directly examining its role during infections. IL-12Rβ2 KO mice were highly susceptible to LVS primary infection, administered i.d. or i.n. The LD50 of LVS infection of KO mice were 2 logs lower than those of WT mice, regardless of route. Five days after infection with LVS, bacterial organ burdens were significantly higher in IL-12Rβ2 KO mice. IL-12Rβ2 KO mice infected with lethal doses of LVS had more severe liver pathology, including significant increases in the liver enzymes ALT and AST. Despite decreased levels of IFN-γ, LVS-vaccinated IL-12Rβ2 KO mice survived large lethal LVS secondary challenge. Consistent with in vivo protection, in vitro intramacrophage LVS growth was well-controlled in cocultures containing WT or IL-12Rβ2 KO LVS-immune splenocytes. Thus, survival of secondary LVS challenge was not strictly dependent on IL-12Rβ2. However, IL-12Rβ2 is important in parenteral and mucosal host resistance to primary LVS infection and in the ability of WT mice to clear LVS infection and serves to restrict liver damage.

Hepatitis B virus surface antigen can activate human monocyte-derived dendritic cells by nuclear factor kappa B and p38 mitogen-activated protein kinase mediated signaling

Hepatitis B virus Ag (HBsAg), a major antigen of hepatitis B virus (HBV), is also a vaccine component for prevention of HBV infection. Dendritic cells (DCs) of HBV carriers reportedly exhibit functional impairment. In this study, the aim was to investigate the effect of HBsAg on activation of human monocyte-derived dendritic cells (MD-DCs), and the subsequent signal transduction pathway. Treatment of MD-DCs with HBsAg resulted in enhanced cell surface expression of cluster of differentiation 80, CD83, CD86 and major histocompatibility complex class II, and increased interleukin (IL)-12 p40, IL-12p70, and IL-10 production. Furthermore, HBsAg treatment of MD-DCs with HBsAg resulted in enhanced T cell-stimulatory capacity and increased T cell secretion of interferon and IL-10. The pathway of MD-DCs activation by HBsAg was further investigated in the present study. Inhibition of nuclear factor (NF)-kappa B (κB) by helenalin and p38 mitogen-activated protein kinase (MAPK) by SB203580 prevented production of IL-12 p40, IL-12 p70, and IL-10. HBsAg also augmented MAPK phosphorylation. Thus, cytokine secretion of human MD-DCs by HBsAg is blocked by inhibition of the NF-κB and p38 MAPK pathways. Likewise, decreased inhibition of kappa B alpha concentrations and MAPK phosphorylation are critical for MD-DC maturation by HBsAg. These findings may provide a strategy for improving the prophylactic and therapeutic efficacy of vaccines and tumor therapies that utilize these pathways.

Bile acids induce monocyte differentiation toward interleukin-12 hypo-producing dendritic cells via a TGR5-dependent pathway

Dendritic cells (DCs) are known as antigen-presenting cells and play a central role in both innate and acquired immunity. Peripheral blood monocytes give rise to resident and recruited DCs in lymph nodes and non-lymphoid tissues. The ligands of nuclear hormone receptors can modulate DC differentiation and so influence various biological functions of DCs. The role of bile acids (BAs) as signalling molecules has recently become apparent, but the functional role of BAs in DC differentiation has not yet been elucidated. We show that DCs derived from human peripheral blood monocytes cultured with a BA produce lower levels of interleukin-12 (IL-12) and tumour necrosis factor-α in response to stimulation with commensal bacterial antigens. Stimulation through the nuclear receptor farnesoid X (FXR) did not affect the differentiation of DCs. However, DCs differentiated with the specific agonist for TGR5, a transmembrane BA receptor, showed an IL-12 hypo-producing phenotype. Expression of TGR5 could only be identified in monocytes and was rapidly down-regulated during monocyte differentiation to DCs. Stimulation with 8-bromoadenosine-cyclic AMP (8-Br-cAMP), which acts downstream of TGR5 signalling, also promoted differentiation into IL-12 hypo-producing DCs. These results indicate that BAs induce the differentiation of IL-12 hypo-producing DCs from monocytes via the TGR5-cAMP pathway.

Quantifying crosstalk among interferon-γ, interleukin-12, and tumor necrosis factor signaling pathways within a TH1 cell model

T helper (T(H)) cells integrate biochemical cues present in the tissue microenvironment and produce cytokines that orchestrate immune responses. Previous discoveries have revealed a qualitative understanding of how T(H) cells process this biochemical information; however, the lack of methods to quantify how well these depictions apply to a particular cell type limits our ability to translate our knowledge of the immune response from one biological system to another. We used model-based inference methods and quantitative flow cytometric analysis in mouse T(H)1 cells to determine the relative contributions of different putative branches in the signaling network that responds to the cytokine interleukin-12 (IL-12), which links innate and adaptive immunity. The response of T(H)1 cells to IL-12 exhibited hysteresis because it depended on both current and past exposure and engaged a positive feedback mechanism through the direct activation of signal transducer and activator of transcription 1. The hysteresis in the dose-response curve to IL-12 created a transient "memory" by sustaining cytokine secretion after the withdrawal of the stimulus. In summary, this combined experimental and computational approach illustrates how model-based inference can be used to better understand how cells process and act upon biochemical cues present in the tissue microenvironment.

HemoHIM ameliorates the persistent down-regulation of Th1-like immune responses in fractionated γ-irradiated mice by modulating the IL-12p70-STAT4 signaling pathway

Whole body irradiated mice appear to experience a down-regulation of the helper T (Th)1-like immune response, and maintain a persistent immunological imbalance. In the current study, we evaluated the effect of HemoHIM (an herbal product made from Angelica Radix, Cnidium officinale , and Paeonia japonica cultivated in Korea) to ameliorate the immunological imbalance induce in fractionated γ-irradiated mice. The mice were exposed to γ rays twice a week (0.5 Gy fractions) for a total dose of 5 Gy, and HemoHIM was administrated orally from 1 week before the first irradiation to 1 week before the final analysis. All experiments were performed 4 and 6 months after their first exposure. HemoHIM ameliorated the Th1- and Th2-related immune responses normally occur in irradiated mice with or without dinitrophenylated keyhole limpet hemocyanin immunization. HemoHIM also restored the natural killer cell activities without changing the percentage of natural killer cells in irradiated mice. Furthermore, the administration of HemoHIM prevented the reduction in levels of interleukin-12p70 in irradiated mice. Finally, we found that HemoHIM enhanced the phosphorylation of signal transducer and activator of transcription (STAT) 4 that was reduced in irradiated mice. Our findings suggest that HemoHIM ameliorates the persistent down-regulation of Th1-like immune responses by modulating the IL-12p70/pSTAT4 signaling pathway.

The immunological contribution of NF-κB within the tumor microenvironment: a potential protective role of zinc as an anti-tumor agent

Over decades, cancer treatment has been mainly focused on targeting cancer cells and not much attention to host tumor microenvironment. Recent advances suggest that the tumor microenvironment requires in-depth investigation for understanding the interactions between tumor cell biology and immunobiology in order to optimize therapeutic approaches. Tumor microenvironment consists of cancer cells and tumor associated reactive fibroblasts, infiltrating non-cancer cells, secreted soluble factors or molecules, and non-cellular support materials. Tumor associated host immune cells such as Th(1), Th(2), Th17, regulatory cells, dendritic cells, macrophages, and myeloid-derived suppressor cells are major components of the tumor microenvironment. Accumulating evidence suggests that these tumor associated immune cells may play important roles in cancer development and progression. However, the exact functions of these cells in the tumor microenvironment are poorly understood. In the tumor microenvironment, NF-κB plays an important role in cancer development and progression because this is a major transcription factor which regulates immune functions within the tumor microenvironment. In this review, we will focus our discussion on the immunological contribution of NF-κB in tumor associated host immune cells within the tumor microenvironment. We will also discuss the potential protective role of zinc, a well-known immune response mediator, in the regulation of these immune cells and cancer cells in the tumor microenvironment especially because zinc could be useful for conditioning the tumor microenvironment toward innovative cancer therapy.

LTβR and CD40: working together in dendritic cells to optimize immune responses

Generating an immune response tailored to destroy an infecting organism while limiting bystander damage involves guiding T-cell activation using a variety of cues taken from the immunogen (antigen type, dose, and persistence, accompanying danger signals) as well as the host (tissue environment, T-cell frequency, and affinity for antigen). Dendritic cells (DCs) serve as translators of much of this information and are critically required for effective pathogen and tumor clearance. Moreover, dysregulation of DC activation can lead to autoimmunity. Inhibition of the lymphotoxin (LT) and CD40 pathways has been shown to be effective at quieting inflammation in settings where DC-T-cell interactions are key instigators of disease progression. In this review, we compare and contrast the CD40 and LT pathways in the context of receptor/ligand expression, signal transduction, and DC biology. We provide evidence that these two pathways play complementary roles in DC cytokine secretion, thus indirectly shaping the nature of the CD8(+) T-cell response to foreign antigen. Given the distinct role of these pathways in the context of DC function, we propose that dual therapies targeted at both the CD40 and LTβ receptor may have therapeutic potential in silencing DC-driven autoimmunity or in promoting tumor clearance.

IFN-γ, IL-17 and TGF-β involvement in shaping the tumor microenvironment: The significance of modulating such cytokines in treating malignant solid tumors

Multiple innate and adaptive immune effector cells and molecules partake in the recognition and destruction of cancer cells to protect against growing tumors, a concept that is known as cancer immunosurveillance. Unfortunately, cancer cells are capable of avoiding this process by immunoselection of poorly immunogenic tumor cells variants along with subversion of the immune system and thus shaping both the tumor and its microenvironment. Cytokines represent part of the complex pattern of the immune response which can assist the development of cancer as well as to eliminate it. Simultaneously, a large number of cytokines may be involved in the complex interactions between host and tumor cells where this dynamic cross-talk, between tumors and the immune system, can either regulate tumor growth or tumor growth, invasion and metastasis take place. In this review, we are stressing on the interface between infiltrated immune cells and tumor cells with the emphasis on the bidirectional activities of specific cytokines: IFN-γ, TGF-β and IL-17 within the tumor microenvironment and their role in shaping it. In addition, the significance of modulating such cytokines in favor of anti-tumor response is discussed and merits the use of mixture of targeted modulators to overcome the network complexity of cytokines in the tumor microenvironment.

Intracellular free zinc up-regulates IFN-γ and T-bet essential for Th1 differentiation in Con-A stimulated HUT-78 cells

Zinc deficiency impairs cellular immunity. Up-regulation of mRNA levels of IFN-γ, IL-12Rβ2, and T-bet are essential for Th(1) differentiation. We hypothesized that zinc increases Th(1) differentiation via up-regulation of IFN-γ and T-bet expression. To test this hypothesis, we used zinc-deficient and zinc-sufficient HUT-78 cells (a Th(0) cell line) under different condition of stimulation in this study. We also used TPEN, a zinc-specific chelator, to decrease the bioavailability of zinc in the cells. We measured intracellular free zinc, cytokines, and the mRNAs of T-bet, IFN-γ, and IL-12Rβ2. In this study, we show that in zinc-sufficient HUT-78 cells, mRNA levels of IFN-γ, IL-12Rβ2, and T-bet in PMA/PHA-stimulated cells were increased in comparison to zinc-deficient cells. Although intracellular free zinc was increased slightly in PMA/PHA-stimulated cells, Con-A-stimulated cells in 5μM zinc medium showed a greater sustained increase in intracellular free zinc in comparison to cells incubated in 1μM zinc. The cells pre-incubated with TPEN showed decreased mRNA levels of IFN-γ and T-bet mRNAs in comparison to cells without TPEN incubation. We conclude that stimulation of cells by Con-A via TCR, release intracellular free zinc which functions as a signal molecule for generation of IFN-γ and T-bet, and IL-12Rβ2 mRNAs required for Th(1) cell differentiation. These results suggest that zinc increase Th(1) cell differentiation by up-regulation of IFN-γ and T-bet, and IL-12Rbβ2 mRNAs.

Hepatitis B virus surface antigen can activate dendritic cells and modulate T helper type immune response

Hepatitis B virus surface antigen (HBsAg) is a major antigen of hepatitis B virus (HBV). Dendritic cells (DC) of HBV carriers have been reported to exhibit functional impairment. In this study, the role of HBsAg on mice bone marrow-derived dendritic cells and immune responses in vivo was studied. The immune modulatory function of HBsAg was explored by using mice bone marrow-derived dendritic cells in vitro and also by examining an ovalbumin (OVA) specific immune response in vivo. Treatment of dendritic cells with HBsAg resulted in enhanced cell surface expression of cluster of differentiation (CD) 80, CD83, CD86, and major histocompatibility complex (MHC) class II, and enhanced production of interleukin (IL)-12 p40 and IL-12 p70. Treatment of dendritic cells with HBsAg resulted in decreased T cell secretion of IL-5 by OVA stimulation. In addition, the results showed stronger OVA-specific immunoglobulin (Ig) M and weaker IgG responses in mice sera when they had been immunized with OVA and co-injected with HBsAg. It was also found that the mice exhibited significant enhancement of anti-OVA IgG2a antibody (Ab), as well as marked inhibition of IgG1 Ab production. In cellular immune responses, IL-5 production was significantly decreased and interferon (IFN)-γ increased in the group co-injected with HBsAg. On the other hand, the induction of lymphoproliferative response to OVA stimulation in spleen cells was decreased in the HBsAg co-injected group. These results demonstrate that HBsAg can affect the differentiation of T helper (Th) cells, which might provide a strategy for improving its prophylactic and therapeutic efficacy.

Chronic effects of single and fractionated γ-irradiation on an impairment of Th1-related immune response

PURPOSE

We already reported that levels of interferon (IFN)-γ have been shown to be markedly reduced in mice seven weeks after irradiation, resulting in a T helper (Th) 1/Th2 imbalance. To investigate whether the single or fractionated γ-irradiation induced an immune imbalance, we analysed the Th1-related immune response profile until six months after the fractionated whole-body irradiation.

METHODS AND MATERIALS

Mice were exposed to γ-rays at a fractionated 5 Gy cumulative dose for five weeks. At two, four and six months later from the first exposure, experiments were performed. Cell populations in the spleen, the production of IFN-γ, interleukin (IL)- 4 and IL-12p70, natural killer (NK) cell activity and the expression of IL-12 receptors, signal transducer and activator of transcription (STAT) 4 and suppressors of cytokine signaling (SOCS) 3 were detected.

RESULTS

The IFN-γ was lower in the mice exposed by all irradiation conditions than in normal control mice, but the IL-4 had increased in all the irradiated mice. To investigate Th1 profile, NK cell activity, IL-12p70 level and its receptor expression was confirmed. In all fractionated irradiation groups, the NK cell activity as well as the absolute numbers of NK cells was much decreased. Also, all the irradiated mice showed a lower IL-12p70 level. However, the expression of IL-12 receptor β2 was lower in the irradiated mice except the 0.2 Gy × 10 mice group. The phosphoylated STAT4 was lower in all the irradiated mice. This suppression was associated with an overexpression of SOCS3.

CONCLUSIONS

The fractionated whole-body irradiations of a dose of 5 Gy appear to be the down-regulation of the Th1-like immune response. These changes, in turn, maintain an immunological imbalance that persists in the long term.

Targeting transcription factor Stat4 uncovers a role for interleukin-18 in the pathogenesis of severe lupus nephritis in mice

Polymorphisms in the transcription factor Stat4 gene have been implicated as risk factors for systemic lupus erythematosus. Although some polymorphisms have a strong association with autoantibodies and nephritis, their impact on pathophysiology is still unknown. To explore this further we used signal transducers and activators of transcription 4 (Stat4) knockout MRL/MpJ-Fas(lpr)/Fas(lpr) (MRL-Fas(lpr)) mice and found that they did not differ in survival or renal function from Stat4-intact MRL-Fas(lpr) mice. Circulating interleukin (IL)-18 levels, however, were elevated in Stat4-deficient compared to Stat4-intact mice, suggesting that this interleukin might contribute to the progression of lupus nephritis independent of Stat4. In a second approach, Stat4 antisense or missense oligonucleotides or vehicle were given to MRL-Fas(lpr) mice with advanced nephritis. Each of these treatments temporarily ameliorated disease, although IL-18 was increased in each setting. Based on these findings, studies using gene transfer to overexpress IL-18 in MRL-Fas(lpr) and IL-12p40/IL-23 knockout MRL-Fas(lpr) mice reveal a critical role for IL-18 in mediating disease. Thus, the Stat4 and IL-12 (an activator of Stat4)-independent factor, IL-18, can drive autoimmune lupus nephritis in MRL-Fas(lpr) mice. Temporarily blocking Stat4 during advanced nephritis ameliorates disease, suggesting a time-dependent compensatory proinflammatory mechanism.

Lasting effects of an impairment of Th1-like immune response in γ-irradiated mice: A resemblance between irradiated mice and aged mice

Although one of the several chronic effects of ionizing radiation is aging, there are no experimental data on radiation-induced immunological aging. The most interesting change in aging was a helper T (Th) 1/Th2 imbalance. We investigated chronic effect on immune responses after ionizing radiation and its effects in irradiated mice were compared with those of aged mice. The 2-month-old mice received a whole-body irradiation of 5Gy. At 6months after irradiation, we compared the immune functions of the irradiated mice with those of normal mice of the same age and with those of older. Interferon (IFN)-γ and antigen-specific immunoglobulin (Ig)G2a level were lower in the irradiated mice than in normal mice of same age, showing similar levels to those of old normal mice. In contrast, interleukin (IL)-4 and IL-5 and antigen-specific IgG1 level were increased in irradiated mice when compared with the same aged-normal mice. Next, we investigated the low expression of IL-12p70, IL-12 receptors and IL-18 receptors in irradiated and old mice. Also, the decrease of natural killer cell activity was intensified in the irradiated mice, showing lower than values to those of old mice. Interestingly, in irradiated mice, the absolute numbers and the percentages of natural killer (NK) cells was extremely decreased. But the absolute numbers of Th cells and cytotoxic T (Tc) cells in old mice were significantly decreased. In conclusion, an immunological imbalance by the whole-body irradiation of 5Gy induces to persist in the long term, resulting in the similar results with aging. Our results suggest that the downregulation of the Th1-like immune response shown in old mice rapidly occurred through exposure of ionizing radiation.

Inferring relevant control mechanisms for interleukin-12 signaling in naïve CD4+ T cells

Interleukin-12 (IL-12) is a key cytokine involved in shaping the cell-mediated immunity to intracellular pathogens. IL-12 initiates a cellular response through the IL-12 signaling pathway, a member of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) family of signaling networks. The JAK/STAT pathway includes several regulatory elements; however, the dynamics of these mechanisms are not fully understood. Therefore, the objective of this study was to infer the relative importance of regulatory mechanisms that modulate the activation of STAT4 in naïve CD4(+) T cells. Dynamic changes in protein expression and activity were measured using flow cytometry and these data were used to calibrate a mathematical model of IL-12 signaling. An empirical Bayesian approach was used to infer the relative strengths of the different regulatory mechanisms in the system. The model predicted that IL-12 receptor expression is regulated by a dynamic, autonomous program that was independent of STAT4 activation. In summary, a mathematical model of the canonical IL-12 signaling pathway used in conjunction with a Bayesian framework provided high-confidence predictions of the system-specific control mechanisms from the available experimental observations.

T helper 17 cells: discovery, function, and physiological trigger

In the few years since their discovery, T helper 17 cells (T(H)17) have been shown to play an important role in host defense against infections, and in tissue inflammation during autoimmunity. T(H)17 cells produce IL-17, IL-21, IL-10, and IL-22 cytokines, and thus have broad effects on a variety of tissues. Notably, the requirement for the immunosuppressive cytokine TGF-beta along with the pro-inflammatory cytokine IL-6 for T(H)17 differentiation supports the intimate relationship between the T(H)17 subset and FOXP3(+) regulatory T cells. Here, we discuss current knowledge on effector functions and differentiation of the T(H)17 lineage. Furthermore, we now know of a physiological stimulus for T(H)17 differentiation: innate immune recognition of cells undergoing apoptosis as a direct result of infection induces unique development of this subset. As our knowledge of T(H)17 and T regulatory cells grows, we are building on a new framework for the understanding of effector T cell differentiation and the biology of CD4(+) T cell adaptive immune responses.

T cells with commitment issues

T cells are a central element of cell-mediated immunity. Host detection of infectious agents leads to antigen presentation and release of cytokines that cause naïve T cells to develop into effector T cells or regulatory T cells (T(reg) cells). Effector T cells act to control the invading agents and mediate tissue inflammation. T(reg) cells maintain immune homeostasis by suppressing effector T cell responses to prevent collateral damage. Until recently, T cell differentiation into distinct subsets with different functions had been considered irreversible. However, new evidence suggests that some differentiated T cell subsets are more phenotypically flexible than others. Studying the plasticity of T cells and the underlying signaling mechanisms may lead to important clues for understanding immunity and autoimmunity.

Interleukin 12 a key immunoregulatory cytokine in infection applications

Interleukin 12 (termed IL-12p70 and commonly designated IL-12) is an important immunoregulatory cytokine that is produced mainly by antigen-presenting cells. The expression of IL-12 during infection regulates innate responses and determines the type of adaptive immune responses. IL-12 induces interferon-γ (IFN-γ) production and triggers CD4⁺ T cells to differentiate into type 1 T helper (Th1) cells. Studies have suggested that IL-12 could play a vital role in treating many diseases, such as viral and bacterial infections and cancers. The unique heterodimeric structure, which IL-12 shares with its family members including IL-23, IL-27, and IL-35, has recently brought more attention to understanding the mechanisms that regulate the functions of IL-12. This article describes the structure and biological activities of IL-12 in both the innate and adaptive arms of the immune system, and discusses the applications of IL-12 in treating and preventing infections.

Th9 and allergic disease

Helper CD4(+) T-cell subsets have improved our understanding of adaptive immunity in humans and in animal models of disease. These include T helper type 1 (Th1), Th2 and the interleukin-17 (IL-17) -producing population 'Th17'. Th2 cells have been described as orchestrating the immune response in allergic disease based on studies with patient samples and animal models. The cytokine IL-9 has largely been regarded as a Th2 cytokine that makes multifocal contributions to allergic disease. Recent data suggest that under certain conditions relevant to chronic disease (IL-4 and transforming growth factor-beta), a distinct population of IL-9-producing 'Th9' helper T cells can exist. The contribution of Th9 cells in allergic disease is currently unknown, and this review will propose a model for how these cells may regulate chronic allergic inflammation.

The effect of caffeic acid phenethyl ester on the functions of human monocyte-derived dendritic cells

Background

Propolis, an ancient herbal medicine, has been reported the beneficial effect both in asthma patients and murine model of asthma, but the mechanism was not clearly understood. In this study, the effect of caffeic acid phenethyl ester (CAPE), the most extensively studied components in propolis, on the functions of human monocyte-derived dendritic cells (MoDCs) was investigated.

Results

CAPE significantly inhibited IL-12 p40, IL-12 p70, IL-10 protein expression in mature healthy human MoDCs stimulated by lipopolysaccharides (LPS) and IL-12 p40, IL-10, IP-10 stimulated by crude mite extract. CAPE significantly inhibited IL-10 and IP-10 but not IL-12 expression in allergic patients' MoDCs stimulated by crude mite extract. In contrast, the upregulation of costimulatory molecules in mature MoDCs was not suppressed by CAPE. Further, the antigen presenting ability of DCs was not inhibited by CAPE. CAPE inhibited IκBα phosphorylation and NF-κB activation but not mitogen-activated protein kinase (MAPK) family phosphorylation in human MoDCs.

Conclusion

These results indicated that CAPE inhibited cytokine and chemokine production by MoDCs which might be related to the NF-κB signaling pathway. This study provided a new insight into the mechanism of CAPE in immune response and the rationale for propolis in the treatment of asthma and other allergic disorders.

Expression of interferon gamma and proinflammatory cytokines in the cecal mucosa of rats experimentally infected with Blastocystis sp. strain RN94-9

Blastocystis hominis is a zoonotic intestinal protozoan parasite whose pathogenic potential is still controversial. The aim of the present study was to clarify the pathogenicity of Blastocystis parasites in rats. Oral inoculation with 1 x 10(5) cysts of Blastocystis sp. strain RN94-9 in rats resulted in chronic infection in the cecum at least until 4 weeks after infection. Histological examination revealed neither mucosal sloughing nor inflammatory cell infiltration but showed a slight but significant increase in goblet cell numbers in the cecal mucosa 1-3 weeks post-infection. Differential staining of acidic and neutral mucins by the alcian blue-periodic acid-Schiff method showed that the predominantly increased cells were neutral mucin(+) but not acidic mucin(+) goblet cells. Reverse transcription real-time polymerase chain reaction studies demonstrated significant upregulation of the expression of interferon-gamma, interleukin (IL)-12, and tumor necrosis factor alpha, but not IL-6 or granulocyte-macrophage colony-stimulating factor, in the cecal mucosa at 2 and/or 3 weeks post-infection. The induction of local host responses, including mild goblet cell hyperplasia, and significant upregulation of type-1 and proinflammatory cytokines, suggest that Blastocystis sp. strain RN94-9 is a weakly pathogenic organism that could elicit proinflammatory as well as protective responses in local tissues.

Signal transducer and activation of transcription (STAT) 4beta, a shorter isoform of interleukin-12-induced STAT4, is preferentially activated by estrogen

Estrogen, a natural immunomodulatory compound, has been shown to promote the induction of a prototype T helper 1 cytokine, interferon (IFN)-gamma, as well as to up-regulate IFNgamma-mediated proinflammatory molecules (nitric oxide, cyclooxygenase 2, monocyte chemoattractant protein 1). Because IL-12 is a major IFNgamma-inducing cytokine, in this study we investigated whether estrogen treatment of wild-type C57BL/6 mice alters IL-12-mediated signaling pathways. A recent study has shown that IL-12 activates two isoforms of signal transducer and activation of transcription (STAT) 4, a normal-sized (full-length STAT4alpha) and a truncated form (STAT4beta). Interestingly, we found that estrogen treatment preferentially up-regulates the phosphorylation of STAT4beta in splenic lymphoid cells. Time kinetic data showed the differential activation of STAT4beta in splenic lymphoid cells from estrogen-treated mice, but not in cells from placebo controls. The activation of STAT4beta was mediated by IL-12 and not IFNgamma because deliberate addition or neutralization of IL-12, but not IFNgamma, affected the activation of STAT4beta. In contrast to IL-12-induced activation of STAT4beta in cells from estrogen-treated mice, STAT4alpha was not increased, rather it tended to be decreased. In this context, STAT4alpha-induced p27(kip1) protein was decreased in concanavalin A + IL-12-activated lymphocytes from estrogen-treated mice only. By using the in vitro DNA binding assay, we confirmed the ability of pSTAT4beta to bind to the IFNgamma-activated sites (IFNgamma activation sequences)/STAT4-binding sites in estrogen-treated mice. Our data are the first to show that estrogen apparently has selective effects on IL-12-mediated signaling by preferentially activating STAT4beta. These novel findings are likely to provide new knowledge with regard to estrogen regulation of inflammation.

Natural killer cells are required for accelerated type 1 diabetes driven by interferon-beta

The destruction of beta cells by the islet infiltrating lymphocytes causes type 1 diabetes. Transgenic mice models expressing interferon (IFN)-beta in beta cells, in the non-obese diabetic (NOD) strain and in a diabetes-free, major histocompatibility complex-matched, homologous strain, the non-obese resistant (NOR) mice, developed accelerated type 1 diabetes after 3 weeks of age. Our aim was to determine if natural killer (NK) cells could affect the acceleration of the disease. We determined the amount of NK cells in the pancreas, spleen and lymph nodes from NOD rat insulin promoter (RIP)-IFN-beta mice. Pancreatic cytokines were assessed by quantitative real-time polymerase chain reaction and protein arrays. To confirm the relevance of NK cells in the acceleration of autoimmune diabetes this subset was depleted with anti-asialo GM1 antibodies. An increase of intrapancreatic NK cells characterized the accelerated onset of diabetes both in NOD and NOR RIP-IFN-beta transgenic models. Cytokines involved in NK function and migration were found to be hyperexpressed in the pancreas from accelerated diabetic mice. Interestingly, the depletion of NK cells in vivo abolished completely the acceleration of diabetes. NK cells connect innate to adaptive immunity and might play a role in autoimmunity. We report here that NK cells are required critically in the pancreas for accelerated diabetes. This model links inflammation to acceleration of beta cell-specific autoimmunity mediated by NK cells.

LIGHT Is critical for IL-12 production by dendritic cells, optimal CD4+ Th1 cell response, and resistance to Leishmania major

Although studies indicate LIGHT (lymphotoxin (LT)-like, exhibits inducible expression and competes with HSV glycoprotein D for herpes virus entry mediator (HVEM), a receptor expressed by T lymphocytes) enhances inflammation and T cell-mediated immunity, the mechanisms involved in this process remain obscure. In this study, we assessed the role of LIGHT in IL-12 production and development of CD4(+) Th cells type one (Th1) in vivo. Bone marrow-derived dendritic cells from LIGHT(-/-) mice were severely impaired in IL-12p40 production following IFN-gamma and LPS stimulation in vitro. Furthermore, blockade of LIGHT in vitro and in vivo with HVEM-Ig and LT beta receptor (LTbetaR)-Ig leads to impaired IL-12 production and defective polyclonal and Ag-specific IFN-gamma production in vivo. In an infection model, injection of HVEM-Ig or LTbetaR-Ig into the usually resistant C57BL/6 mice results in defective IL-12 and IFN-gamma production and severe susceptibility to Leishmania major that was reversed by rIL-12 treatment. This striking susceptibility to L. major in mice injected with HVEM-Ig or LTbetaR-Ig was also reproduced in LIGHT(-/-) --> RAG1(-/-) chimeric mice. In contrast, L. major-infected LTbeta(-/-) mice do not develop acute disease, suggesting that the effect of LTbetaR-Ig is not due to blockade of membrane LT (LTalpha1beta2) signaling. Collectively, our data show that LIGHT plays a critical role for optimal IL-12 production by DC and the development of IFN-gamma-producing CD4(+) Th1 cells and its blockade results in severe susceptibility to Leishmania major.

Effect of danazol on NK cells and cytokines in the mouse uterus

Danazol, which has been used as a medicine for endometriosis, has a valid effect in pretreatment of patients receiving in vitro fertilization and embryo transfer, although its reproductive mechanism remains unclear. BALB/c mice were subcutaneously injected with danazol for 2 weeks. Blood and uteri were collected and cytokines were assayed. Following danazol treatment, an increase in pregnancy ratio was evident that was accompanied by up-regulation in serum macrophage-colony stimulating factor (M-CSF). RT-PCR analysis revealed that expression of M-CSF and Ly49, a phenotypic marker of natural killer (NK) cells, was up-regulated in the uteri of the danazol-treated mice. In immunohistochemical analysis, M-CSF and Ly49, together with alpha5 integrin, were clearly detected in the endometrium of the danazol-treated mice with very similar pattern of localization. These results suggest that danazol has an effect to promote pregnancy that induces recruitment of NK cells and a concomitant increase in the expression of M-CSF and alpha5 integrin in the uterus.

Selective abrogation of Th1 response by STA-5326, a potent IL-12/IL-23 inhibitor

The interleukin-12 (IL-12) cytokine induces the differentiation of naive T cells to the T helper cell type 1 (Th1) phenotype and is integral to the pathogenesis of Th1-mediated immunologic disorders. A more recently discovered IL-12 family member, IL-23, shares the p40 protein subunit with IL-12 and plays a critical role in the generation of effector memory T cells and IL-17-producing T cells. We introduce a novel compound, STA-5326, that down-regulates both IL-12 p35 and IL-12/IL-23 p40 at the transcriptional level, and inhibits the production of both IL-12 and IL-23 cytokines. Oral administration of STA-5326 led to a suppression of the Th1 but not Th2 immune response in mice. In vivo studies using a CD4+CD45Rbhigh T-cell transfer severe combined immunodeficiency (SCID) mouse inflammatory bowel disease model demonstrated that oral administration of STA-5326 markedly reduced inflammatory histopathologic changes in the colon. A striking decrease in interferon-gamma (IFN-gamma) production was observed in ex vivo culture of lamina propria cells harvested from animals treated with STA-5326, indicating a down-regulation of the Th1 response by STA-5326. These results suggest that STA-5326 has potential for use in the treatment of Th1-related autoimmune or immunologic disorders. STA-5326 currently is being evaluated in phase 2 clinical trials in patients with Crohn disease and rheumatoid arthritis.

Expression of IL-4 receptor on non-bone marrow-derived cells is necessary for the timely elimination of Strongyloides venezuelensis in mice, but not for intestinal IL-4 production

In rodents and in humans, Strongyloides infection induces an immune response which is predominantly Th2 in nature. In an attempt to understand the role of the IL-4R/STAT6 signaling pathway, the pathway activated by the Th2 cytokines IL-4 and IL-13, in the induction of protection during Strongyloides venezuelensis infection, we have carried out experiments in mice lacking the IL-4Ralpha chain. Experiments were also carried out in STAT6 (STAT6(-/-)) and IL-12-deficient (IL-12(-/-)) mice for comparison. There was enhancement of IL-13 and abolition of IFN-gamma production in the small intestine of 7 day-infected IL-12(-/-) animals but worm elimination proceeded with very similar kinetics to those of wild-type mice. In IL-4Ralpha- or STAT6-deficient mice, there was a delay in parasite elimination and a large number of S. venezuelensis adult worms was still present in the small intestine 14 days after infection. Moreover, IgE production was completely abolished in IL-4Ralpha- or STAT6-deficient mice but tissue eosinophilia was normally induced by the parasite infection in deficient mice. Bone marrow transfer experiments showed that worm elimination occurred when a functional IL-4 receptor was present only in non-bone marrow-derived cells but not when IL-4R was only expressed in bone marrow cells. The induction of IL-4, but not IL-13, occurred independently of IL-4R. We believe these results are the first direct evidence that the mechanism responsible for the timely elimination of S. venezuelensis is dependent on the activation of IL-4R and STAT6. Moreover, a functional protective response is dependent on the expression of IL-4Ralpha on non-bone marrow-derived cells.

Type I cytokine profiles of human naïve and memory B lymphocytes: a potential for memory cells to impact polarization

B cells bifurcating along 'type 1' or 'type 2' pathways under the influence of polarizing cytokines can, in turn, influence the direction of an immune response. Here, we compare the capacity of human B cells residing within naïve and memory compartments to participate in type 1 polarizing responses. B-cell receptor (BCR) engagement provided the main signal for interleukin (IL)-12Rbeta1 expression in the two subsets: this was potentiated by CD154 together with interferon-gamma (IFN-gamma) but inhibited by IL-12. IL-12Rbeta2 could be induced on a minority of B cells by the same signals, and also by IFN-gamma alone. WSX-1, a receptor for IL-27, was expressed in both subsets with no evidence for its regulation by the signals studied. While neither subset was capable of secreting much IL-12 p70, memory B cells could produce a small amount of IL-12 p40 on CD40 ligation. Memory B cells also, exclusively, expressed IL-23 p19 mRNA on BCR triggering. Importantly, products of appropriately stimulated memory--but not naive--B cells were shown to promote the synthesis of IFN-gamma in uncommitted T-helper cells. The data indicate an equal capacity for naïve and memory B cells to respond within a type 1 polarizing environment. Although poorly equipped for initiating type 1 responses, B cells--by virtue of the memory subset--reveal a capacity for their maintenance and amplification following T-dependent signalling.

Role of H1 receptors in histamine-mediated up-regulation of STAT4 phosphorylation

Histamine shifts TH1/TH2 cytokine balance from TH1 to TH2 cytokines and regulates the function of lymphocytes after binding to histamine receptors. The phosphorylation of STAT factors and the translocation to the nucleus are important steps in the regulation of TH1/TH2 cytokine balance. This study was designed to investigate the effects of histamine on the phosphorylation of STAT4. C57BL/6 splenocytes were isolated and treated with histamine (10(-4) to 10(-9) M) after activation with either PMA (phorbol 12 myristate 13-acetate) plus ionomycin or IL-12. The phosphorylated STAT4 levels were analyzed by Western Blot Analysis. Unstimulated splenocytes expressed both STAT4 and phosphorylated STAT4. However, phosphorylated STAT4 gradually declined within 24 h. Histamine increased the phosphorylation of STAT4 at lower concentrations (10(-6) to 10(-9) M), and had no effect at higher concentrations (10(-4) and 10(-5) M) after the cells were stimulated with PMA + ionomycin. Histamine did not affect IL-12-induced phosphorylation of STAT4. To characterize the histamine receptor subtypes involved in the up-regulation of STAT4 phosphorylation, various H1, H2 and H3/H4 receptor antagonists and/or agonists were employed. H1 receptor agonist (betahistine), but not H2 receptor agonist (amthamine), induced phosphorylation of STAT4. H1 receptor antagonist (pyrilamine) inhibited histamine-mediated phosphorylation of STAT4. However, H2 receptor antagonist (ranitidine) and H3/H4 receptor antagonist (thioperamide) did not alter this effect. Tyrosine kinase inhibitor (tyrphostin) failed to block histamine-mediated phosphorylation of STAT4. These observations suggest that histamine up-regulated the phosphorylation of STAT4 via H1 receptors, and that the Ca2+-PKC pathway, but not the tyrosine kinase pathway, was involved in this effect.

Mononuclear phagocytes in the pathogenesis of neurodegenerative diseases

Brain mononuclear phagocytes (MP, bone marrow monocyte-derived macrophages, perivascular macrophages, and microglia) function to protect the nervous system by acting as debris scavengers, killers of microbial pathogens, and regulators of immune responses. MP are activated by a variety of environmental cues and such inflammatory responses elicit cell injury and death in the nervous system. MP immunoregulatory responses include secretion of neurotoxic factors, mobilization of adaptive immunity, and cell chemotaxis. This incites tissue remodelling and blood-brain barrier dysfunction. As disease progresses, MP secretions engage neighboring cells in a vicious cycle of autocrine and paracrine amplification of inflammation leading to tissue injury and ultimately destruction. Such pathogenic processes tilt the balance between the relative production of neurotrophic and neurotoxic factors and to disease progression. The ultimate effects that brain MP play in disease revolves "principally" around their roles in neurodegeneration. Importantly, common functions of brain MP in neuroimmunity link highly divergent diseases (for example, human immunodeficiency virus type-one associated dementia, Alzheimer's disease and Parkinson's disease). Research into this process from our own laboratories and those of others seek to harness MP inflammatory processes with the intent of developing therapeutic interventions that block neurodegenerative processes and improve the quality of life in affected people.