Expression and function of IL-12 and IL-18 receptors on human tonsillar B cells

A Narrative Review of the IL-18 and IL-37 Implications in the Pathogenesis of Atopic Dermatitis and Psoriasis: Prospective Treatment Targets

Atopic dermatitis and psoriasis are prevalent inflammatory skin conditions that significantly impact the quality of life of patients, with diverse treatment options available. Despite advances in understanding their underlying mechanisms, recent research highlights the significance of interleukins IL-18 and IL-37, in Th1, Th2, and Th17 inflammatory responses, closely associated with the pathogenesis of psoriasis and atopic dermatitis. Hence, IL-18 and IL-37 could potentially become therapeutic targets. This narrative review synthesizes knowledge on these interleukins, their roles in atopic dermatitis and psoriasis, and emerging treatment strategies. Findings of a literature search up to 30 May 2024, underscore a research gap in IL-37-targeted therapies. Conversely, IL-18-focused treatments have demonstrated promise in adult-onset Still's Disease, warranting further exploration for their potential efficacy in psoriasis and atopic dermatitis.

IL-12 induces a B cell-intrinsic IL-12/IFNγ feed-forward loop promoting extrafollicular B cell responses

While some infections elicit germinal centers, others produce only extrafollicular responses. The mechanisms controlling these dichotomous fates are poorly understood. We identify IL-12 as a cytokine switch, acting directly on B cells to promote extrafollicular and suppress germinal center responses. IL-12 initiates a B cell-intrinsic feed-forward loop between IL-12 and IFNγ, amplifying IFNγ production, which promotes proliferation and plasmablast differentiation from mouse and human B cells, in synergy with IL-12. IL-12 sustains the expression of a portion of IFNγ-inducible genes. Together, they also induce unique gene changes, reflecting both IFNγ amplification and cooperative effects between both cytokines. In vivo, cells lacking both IL-12 and IFNγ receptors are more impaired in plasmablast production than those lacking either receptor alone. Further, B cell-derived IL-12 enhances both plasmablast responses and T helper 1 cell commitment. Thus, B cell-derived IL-12, acting on T and B cells, determines the immune response mode, with implications for vaccines, pathogen protection and autoimmunity.

Analysis of Changes in Plasma Cytokine Levels in Response to IL12 Therapy in Three Clinical Trials

The ability of IL12 to stimulate natural killer (NK) cell and T-cell antitumor activity makes it an attractive candidate for the immune therapy of cancer. Our group has demonstrated that IL12 enhances the NK cell response to antibody-coated tumor cells and conducted three clinical trials utilizing IL12 with mAbs (OSU-9968, OSU-0167, and OSU-11010). To better characterize IL12-induced immunity, plasma cytokine levels were measured in 21 patients from these trials with favorable and unfavorable responses. t-statistics and linear modeling were used to test for differences within and between response groups by examining levels at baseline and post-IL12 administration. Patients exhibited significant increases in 11 cytokines post-IL12 administration when analyzed collectively. However, several cytokines were differentially induced by IL12 depending on response. GMCSF was significantly increased in complete/partially responding patients, while stable disease patients had significant increases in IL10 and decreases in VEGF-C. Patients who experienced progressive disease had significant increases in CCL3, CCL4, IL18, TNFα, CXCL10, CCL8, CCL2, IL6, and IFNγ. The increases in CCL3, CCL4, and IL6 in progressive disease patients were significantly higher than in clinically benefitting patients and most prominent within the first two cycles of IL12 therapy. This correlative pilot study has identified changes that occur in levels of circulating cytokines following IL12 administration to patients with cancer, but this report must be viewed as exploratory in nature. It is meant to spark further inquiry into the topic via the analysis of additional cohorts of patients with similar characteristics who have received IL12 in a uniform fashion.

SIGNIFICANCE

IL12 activates immune cells and is used to treat cancer. The profile of circulating cytokines was measured in an exploratory fashion in patients with cancer that received IL12 in combination with mAbs. This correlative pilot study could serve as the basis for additional studies of IL12 effects on the production of immune cytokines.

Biological and clinical roles of IL-18 in inflammatory diseases

Several new discoveries have revived interest in the pathogenic potential and possible clinical roles of IL-18. IL-18 is an IL-1 family cytokine with potent ability to induce IFNγ production. However, basic investigations and now clinical observations suggest a more complex picture. Unique aspects of IL-18 biology at the levels of transcription, activation, secretion, neutralization, receptor distribution and signalling help to explain its pleiotropic roles in mucosal and systemic inflammation. Blood biomarker studies reveal a cytokine for which profound elevation, associated with detectable 'free IL-18', defines a group of autoinflammatory diseases in which IL-18 dysregulation can be a primary driving feature, the so-called 'IL-18opathies'. This impressive specificity might accelerate diagnoses and identify patients amenable to therapeutic IL-18 blockade. Pathogenically, human and animal studies identify a preferential activation of CD8+ T cells over other IL-18-responsive lymphocytes. IL-18 agonist treatments that leverage the site of production or subversion of endogenous IL-18 inhibition show promise in augmenting immune responses to cancer. Thus, the unique aspects of IL-18 biology are finally beginning to have clinical impact in precision diagnostics, disease monitoring and targeted treatment of inflammatory and malignant diseases.

Transcriptomic analysis of human cytomegalovirus to survey the indirect effects on renal transplant recipients

Post-transplant human cytomegalovirus (HCMV) viremia has been linked to adverse "indirect effects" among transplant patients. HCMV-created immunomodulatory mechanisms could be associated with the indirect effects.

OBJECTIVE

In the present study, the RNA-Seq whole transcriptome of renal transplant (RT) patients was analyzed to seek the underlying pathobiologic pathways associated with the long-term indirect effects of HCMV.

METHODS

To investigate the activated biological pathways in HCMV infection, total RNA was extracted from PBMCs of 2 RT patients with active HCMV and 2 RT patients without infection and then were sequenced using RNA-Seq. The resulted raw data were analyzed by conventional RNA-Seq software to determine the Differentially Expressed Genes (DEGs). Afterward, Gene Ontology (GO) and pathway enrichment analyses were conducted to determine the enriched pathways and biological processes by DEGs. Eventually, the relative expressions of some significant genes were validated in the twenty external RT patients.

RESULT

The analysis of RNA-Seq data related to RT patients with HCMV active viremia led to the identification of 140 up-regulated and 100 down-regulated DEGs. KEGG pathway analysis revealed the enrichment of DEGs in IL18 signaling, AGE-RAGE signaling pathway in diabetic complications, signaling by GPCR, Platelet activation, signaling and aggregation, Estrogen signaling pathway and signaling by Wnt due to HCMV infection. The expression levels of six genes involved in enriched pathways including F3, PTX3, ADRA2B, GNG11, GP9, HBEGF were then verified using RT-qPCR. The results were in consistent with RNA-Seq resultsoutcomes.

CONCLUSION

This study specifies some pathobiological pathways which are activated in HCMV active infection and could be linked to the adverse indirect effects caused by HCMV infection in transplant patients.

Analysis of potential biomarkers of response to IL‐12 therapy

IL‐12 is a proinflammatory cytokine capable of inducing a wide range of effects on both innate and adaptive immune responses. Its stimulatory effects on T cells and NK cells have led to its classification as a potential inducer of antitumor immunity. Clinical trials have been attempting to harness its immune‐stimulating capacity since the 1990s and have had much success despite notable toxicity issues early on. Several methods of IL‐12 delivery have been employed including i.v., s.c., and local administrations as well as plasmid and gene therapies. However, despite differing methods, dosages, and cancer types utilized in these clinical trials, there are still many patients who do not respond to IL‐12 therapy. This creates an opportunity for further investigation into the immunologic differences between responding and nonresponding patients in order to better understand the variable efficacy of IL‐12 therapy. This review focuses on a limited collection of IL‐12 clinical trials, which further analyzed these individual subsets and detected biologic variables correlating with differential patient responses. A comprehensive review of these potential biomarkers identified 7 analytes that correlated with beneficial patient responses in 3 or more clinical trials. These were increased levels of IFN‐γ, IP‐10, TNF‐α, MIP‐1α, MIG, and CD4⁺ and CD8⁺ T cells, with a decrease in VEGF, bFGF, FoxP3⁺ T regulatory cells, and M2 macrophages. These potential biomarkers highlight the possibility of identifying immunologic determinants of patient response to IL‐12 therapy to conserve valuable resources and benefit patients.

Schnitzler syndrome and Schnitzler-like syndromes

Schnitzler syndrome is a rare disease of adult-onset with main features including chronic urticarial rash, recurrent fever, arthralgia or arthritis, monoclonal gammopathy of undetermined significance (MGUS), and marked systemic inflammation. Schnitzler syndrome is often underdiagnosed. Patients with Schnitzler syndrome may present to dermatologists and allergists for urticaria, hematologists for MGUS, or rheumatologists for arthritis. It is important to recognize Schnitzler syndrome for its remarkable response to interleukin (IL)-1 blockade. Besides, many cases of Schnitzler-like syndromes do not meet the diagnostic criteria of classical Schnitzler syndrome but display excellent response to IL-1 inhibitors. The overly produced IL-1 is the result of a somatic mosaic gain of function mutation of NLRP3 (nucleotide-binding oligomerization domain [NOD]-like receptor [NLR] family pyrin domain containing 3) gene in some patients with Schnitzler-like syndromes. Inflammasome activation is evident in patients with classical Schnitzler syndrome although no NLRP3 gene mutation is identified. Collectively, Schnitzler syndrome and Schnitzler-like syndromes represent a spectrum of IL-1 mediated adult-onset autoinflammatory diseases.

Engineered Cytokine Signaling to Improve CAR T Cell Effector Function

Adoptive immunotherapy with T cells genetically modified to express chimeric antigen receptors (CARs) is a promising approach to improve outcomes for cancer patients. While CAR T cell therapy is effective for hematological malignancies, there is a need to improve the efficacy of this therapeutic approach for patients with solid tumors and brain tumors. At present, several approaches are being pursued to improve the antitumor activity of CAR T cells including i) targeting multiple antigens, ii) improving T cell expansion/persistence, iii) enhancing homing to tumor sites, and iv) rendering CAR T cells resistant to the immunosuppressive tumor microenvironment (TME). Augmenting signal 3 of T cell activation by transgenic expression of cytokines or engineered cytokine receptors has emerged as a promising strategy since it not only improves CAR T cell expansion/persistence but also their ability to function in the immunosuppressive TME. In this review, we will provide an overview of cytokine biology and highlight genetic approaches that are actively being pursued to augment cytokine signaling in CAR T cells.

Interleukin-18 in Inflammatory Kidney Disease

Interleukin (IL)-18, a member of the IL-1 superfamily, is a pro-inflammatory cytokine that is structurally similar to IL-1β. IL-18 promotes the production of interferon gamma (IFN-γ) and strongly induces a Th1 response. IL-18 drives the same myeloid differentiation factor 88 (MyD88)/nuclear factor kappa B (NF-κB) signaling pathway as IL-1β. In physiological conditions, IL-18 is regulated by the endogenous inhibitor IL-18 binding protein (IL-18BP), and the activity of IL-18 is balanced. It is reported that in several inflammatory diseases, the IL-18 activity is unbalanced, and IL-18 neutralization by IL-18BP is insufficient. IL-18 acts synergistically with IL-12 to induce the production of IFN-γ as a Th1 cytokine, and IL-18 acts alone to induce the production of Th2 cytokines such as IL-4 and IL-13. In addition, IL-18 alone enhances natural killer (NK) cell activity and FAS ligand expression. The biological and pathological roles of IL-18 have been studied in many diseases. Here we review the knowledge regarding IL-18 signaling and the role of IL-18 in inflammatory kidney diseases. Findings on renal injury in coronavirus disease 2019 (COVID-19) and its association with IL-18 will also be presented.

Targeted Delivery of IL-12 Adjuvants Immunotherapy by Oncolytic Viruses

The great hopes raised by the discovery of the immunoregulatory cytokine interleukin 12 (IL-12) as an anticancer agent were marred during early clinical experimentation because of severe adverse effects, which prompted a search for alternative formulations and routes of administration. Onco-immunotherapeutic viruses (OIVs) are wild-type or genetically engineered viruses that exert antitumor activity by causing death of the tumor cells they infect and by overcoming a variety of immunosuppressive mechanisms put in place by the tumors. OIVs have renewed the interest in IL-12, as they offer the opportunity to encode the cytokine transgenically from the viral genome and to produce it at high concentrations in the tumor bed. A large body of evidence indicates that IL-12 serves as a potent adjuvant for the immunotherapeutic response elicited by OIVs in murine tumor models. The list of OIVs includes onco-immunotherapeutic herpes simplex, adeno, measles, Newcastle disease, and Maraba viruses, among others. The large increase in IL-12-mediated adjuvanticity was invariably observed for all the OIVs analyzed. Indirect evidence suggests that locally delivered IL-12 may also increase tumor antigenicity. Importantly, the OIV/IL-12 treatment was not accompanied by adverse effects and elicited a long-lasting immune response capable of halting the growth of distant tumors. Thus, OIVs provide an avenue for reducing the clinical toxicity associated with systemic IL-12 therapy, by concentrating the cytokine at the site of disease. The changes to the tumor microenvironment induced by the IL-12-armed OIVs primed the tumors to an improved response to the checkpoint blockade therapy, suggesting that the triple combination is worth pursuing in the future. The highly encouraging results in preclinical models have prompted translation to the clinic. How well the IL-12-OIV-checkpoint inhibitors' combination will perform in humans remains to be fully investigated.

The Differentiation in vitro of Human Tonsil B Cells With the Phenotypic and Functional Characteristics of T-bet+ Atypical Memory B Cells in Malaria

Malaria is a deadly infectious disease associated with fundamental changes in the composition of the memory B cell (MBC) compartment, most notably a large expansion of T-bet⁺ MBCs, termed atypical MBCs. However, we know little about the precursors of atypical MBCs and the conditions that drive their differentiation. We compared the responses of human tonsil naïve B cells, MBCs, and germinal center B cells to a variety of stimulatory conditions. We determined that prolonged antigen presentation in the presence of CpG and IFN-γ induced maximal expression of T-bet and other phenotypic markers of malaria-associated atypical MBCs primarily in naïve B cells in vitro. Importantly T-bet⁺ naïve-derived B cells resembled atypical MBCs in their hypo-responsiveness to signaling through their B cell receptors. Thus, naïve B cells can be induced to differentiate into phenotypically and functionally atypical-like MBCs in vitro under conditions that may prevail in chronic infectious diseases in vivo.

Lipid nanoparticles that deliver IL-12 messenger RNA suppress tumorigenesis in MYC oncogene-driven hepatocellular carcinoma

Interleukin-12 (IL-12) is a promising candidate for cancer immunotherapy because of its ability to activate a number of host immune subsets that recognize and destroy cancer cells. We found that human hepatocellular carcinoma (HCC) patients with higher than median levels of IL-12 have significantly favorable clinical outcomes. Here, we report that a messenger RNA (mRNA) lipid nanoparticle delivering IL-12 (IL-12-LNP) slows down the progression of MYC oncogene-driven HCC. IL-12-LNP was well distributed within the HCC tumor and was not associated with significant animal toxicity. Treatment with IL-12-LNP significantly reduced liver tumor burden measured by dynamic magnetic resonance imaging (MRI), and increased survival of MYC-induced HCC transgenic mice in comparison to control mice. Importantly, IL-12-LNP exhibited no effect on transgenic MYC levels confirming that its therapeutic efficacy was not related to the downregulation of a driver oncogene. IL-12-LNP elicited marked infiltration of activated CD44⁺ CD3⁺ CD4⁺ T helper cells into the tumor, and increased the production of Interferon γ (IFNγ). Collectively, our findings suggest that IL-12-LNP administration may be an effective immunotherapy against HCC.

Synoviocytes-derived Interleukin 35 Potentiates B Cell Response in Patients with Osteoarthritis and Rheumatoid Arthritis

OBJECTIVE

Elevated expression of interleukin 35 (IL-35) is associated with autoimmune disease, including rheumatoid arthritis (RA). The present study was undertaken to determine the functional interaction among IL-35, B cells, and stromal cells residing in the synovium of patients with RA and osteoarthritis (OA).

METHODS

IL-35 (EBI-3/p35) expression was investigated in RA and OA synovium using quantitative real-time PCR (qRT-PCR) and immunohistochemistry. IL-35 receptor (IL-35R) expression on B cells dissociated from synovium and periphery of patients with RA, OA, and healthy donor controls (HC) was determined by flow cytometry. The degree of B cells activation after IL-4 and/or IL-35 stimulation was measured by flow cytometry and qRT-PCR. Synovial fibroblasts (SF) purified from RA and OA synovium were cocultured with peripheral HC B cells in the presence/absence of tumor necrosis factor-α (TNF-α) and with/without anti-IL-35-blocking antibodies.

RESULTS

EBI-3/p35 transcripts were expressed in close proximity to B cells residing in RA and OA synovium. IL-35R subunits, gp130 and IL-27Rα, but not IL-12Rβ2, were expressed in B cells extracted from the synovium and periphery of patients with RA/OA. Notably, RA synovium expressed the highest level of IL-27Rα on their cell surface. IL-35 induced proliferation and IgG production in HC B cells. Cocultures of HC B cells with RASF, but not OASF, exhibited significantly elevated B cells activation. TNF-α-induced, RASF-dependent secretion of IgG in B cells is partly IL-35-dependent.

CONCLUSION

To our knowledge, for the first time we demonstrated that synovial/peripheral B cells expressed IL-35R and were responsive to IL-35 stimulation. SF residing in RA synovium can be linked to B cell activation and maintenance in RA synovium through IL-35.

Experimental vaccine induces Th1-driven immune responses and resistance to Neisseria gonorrhoeae infection in a murine model

Female mice were immunized intravaginally with gonococcal outer membrane vesicles (OMVs) plus microencapsulated interleukin-12 (IL-12), and challenged using an established model of genital infection with Neisseria gonorrhoeae. Whereas sham-immunized and control animals cleared the infection in 10-13 days, those immunized with OMV plus IL-12 cleared infection with homologous gonococcal strains in 6-9 days. Significant protection was also seen after challenge with antigenically distinct strains of N. gonorrhoeae, and protective anamnestic immunity persisted for at least 6 months after immunization. Serum and vaginal immunoglobulin G (IgG) and IgA antibodies were generated against antigens expressed by homologous and heterologous strains. Iliac lymph node CD4⁺ T cells secreted interferon-γ (IFNγ), but not IL-4, in response to immunization, and produced IL-17 in response to challenge regardless of immunization. Antigens recognized by immunized mouse serum included several shared between gonococcal strains, including two identified by immunoproteomics approaches as elongation factor-Tu (EF-Tu) and PotF3. Experiments with immunodeficient mice showed that protective immunity depended upon IFNγ and B cells, presumably to generate antibodies. The results demonstrated that immunity to gonococcal infection can be induced by immunization with a nonliving gonococcal antigen, and suggest that efforts to develop a human vaccine should focus on strategies to generate type 1 T helper cell (Th1)-driven immune responses in the genital tract.

IL-18 Drives ILC3 Proliferation and Promotes IL-22 Production via NF-κB

Group 3 innate lymphoid cells (ILC3s) are important regulators of the immune system, maintaining homeostasis in the presence of commensal bacteria, but activating immune defenses in response to microbial pathogens. ILC3s are a robust source of IL-22, a cytokine critical for stimulating the antimicrobial response. We sought to identify cytokines that can promote proliferation and induce or maintain IL-22 production by ILC3s and determine a molecular mechanism for this process. We identified IL-18 as a cytokine that cooperates with an ILC3 survival factor, IL-15, to induce proliferation of human ILC3s, as well as induce and maintain IL-22 production. To determine a mechanism of action, we examined the NF-κB pathway, which is activated by IL-18 signaling. We found that the NF-κB complex signaling component, p65, binds to the proximal region of the IL22 promoter and promotes transcriptional activity. Finally, we observed that CD11c+ dendritic cells expressing IL-18 are found in close proximity to ILC3s in human tonsils in situ. Therefore, we identify a new mechanism by which human ILC3s proliferate and produce IL-22, and identify NF-κB as a potential therapeutic target to be considered in pathologic states characterized by overproduction of IL-18 and/or IL-22.

Interleukin-31 and thymic stromal lymphopoietin expression in plasma and lymph node from Hodgkin lymphoma patients

Hodgkin Lymphoma (HL) is a tumor of B-cell origin characterized by Hodgkin and Reed-Stenberg (H/RS) cells embedded in an inflammatory tissue where numerous cytokines/chemokines contribute to shape the microenvironment, leading to the typical clinical symptoms.

We investigated: i) the expression of Interleukin-IL-31 (IL-31) and Thymic Stromal Lymphopoietin (TSLP), two Th2-related cytokines with tumor-promoting and pruritogenic functions, and of the respective receptors in HL invaded lymph nodes by flow cytometry, and ii) the potential association of IL-31/TSLP plasma concentrations with clinical characteristics by ELISA.

H/RS cells and the major immune cell types infiltrating HL lymph nodes expressed intracytoplasmic and surface IL-31/TSLP, and their receptors. A subgroup of patients showing at diagnosis elevated IL-31 and TSLP plasma levels had an International Prognostic Score>2, indicative of high risk of relapse, and a subsequent positive interim PET-scan, indicative of insufficient response to chemotherapy. No correlation was found between IL-31/TSLP plasma levels and overall or event-free survival.

In conclusion, IL-31/TSLP and their receptors are expressed in HL cells and in immune cells infiltrating affected lymph nodes, where both cytokines may contribute to local immune suppression. The clinical impact of IL-31 and TSLP plasma levels has to be further defined in larger patient cohorts.

Evidence for the existence of regulatory and effector B cell populations in Peyer's patches of sheep

IL-10 secreting CD21(+) B cells exist in sheep Peyer's patches (PP). It's not known however, whether all PP B cells are regulatory or whether an effector population also exists in this tissue. To further characterize the subpopulations of B cells in PP's, highly purified B cells were negatively sorted from jejunal PP and fractionated according to co-expression of CD72(+)CD21(+)or CD72(+)CD21(-) molecules and then stimulated with the TLR9-agonist, CpG ODN. IL-10, IL-12, IFN-γ, and IgM production were then assayed. We observed that only highly purified CD72(+)CD21(+) B cells spontaneously secreted high levels of IL-10, but they did not produce any IL-12, IFN-γ or IgM suggesting that this cell population contains regulatory B cells. In contrast, CD72(+)CD21(-) B cells did not secrete IL-10, but secreted IL-12, IFN-γ, and IgM, suggesting they include effector cells. In addition, B cells expressing surface IgA, IgM and IgG1 all secreted similar levels of IL-10. We further confirmed that only B cells produce IL-10, while other cells in the PP including DCs and T cells do not. Our investigations may provide evidence for the existence of two sub-populations in sheep PP; IL-10 secreting regulatory (CD72(+)CD21(+)) cells, and IL-12/IFN-γ/IgM-secreting effector (CD72(+)CD21(-)) cells.

Functional analysis of differences in transcriptional activity conferred by genetic variants in the 5' flanking region of the IL12RB2 gene

Interleukin 12 receptor β chain (IL12RB2) is a crucial regulatory factor involved in cell-mediated immune responses, and genetic variants of the gene encoding IL12RB2 are associated with susceptibility to various immune-related diseases. We previously demonstrated that haplotypes with single nucleotide polymorphisms (SNPs) in the 5' flanking region of IL12RB2, including -1035A>G (rs3762315) and -1023A>G (rs3762316), affect the expression of IL12RB2, thereby altering susceptibility to leprosy and periodontal diseases. In the present study, we identified transcription factors associated with the haplotype-specific transcriptional activity of IL12RB2 in T cells and NK cells. The -1023G polymorphism was found to create a consensus binding site for the transcription factor activating protein (AP)-1, and enzyme-linked immunosorbent assay (ELISA)-based binding assays showed that these SNPs enhanced AP-1 binding to this region. In reporter assays, suppression of JunB expression using siRNA eliminated differences in the -1035G/-1023G and -1035A/-1023A regions containing IL12RB2 promoter activity in Jurkat T cells and NK3.3 cells. These results suggested that the -1035/-1023 polymorphisms created differential binding affinities for JunB that could lead to differential IL12RB2 expression. Moreover, the -1035G and -1035A alleles formed binding sites for GATA-3 and myocyte enhancer factor-2 (MEF-2), respectively. Our data indicated that in addition to JunB, the SNP at -1035/-1023 influenced GATA-3 and MEF-2 binding affinity, potentially altering IL12RB2 transcriptional activity. These findings confirm the effects of rs3762315 and rs3762316 on IL12RB2 transcription. These genetic variants may alter cellular activation of T cells and NK cells and modify cell-mediated immune responses.

IL12RB2 Polymorphisms correlate with risk of lung adenocarcinoma

In a previous study, lack of IL-12 signaling in il12rb2 knock-out mice was found to predispose to lung adenocarcinoma (LAC). We asked whether specific polymorphisms of the human IL12RB2 gene may confer susceptibility to LAC. We studied IL12RB2 single nucleotide polymorphisms (SNPs) spanning from the promoter to the first untranslated exon of the gene. Genotypes of 49 individuals with LAC were compared with those of 93 healthy subjects. Two allele variants were found to be associated with increased susceptibility to LAC. One haplotype (hap), hap18, was more frequent in patients (18%) versus controls (6%) and significantly associated with increased probability of disease occurrence. Furthermore, IL-12 driven STAT4 phosphorylation in T cell blasts from healthy individuals was found to correlate with both single allele variants and haplotypes. In conclusion, genetically determined low signaling activity of IL-12R predisposes to the development of LAC.

Aberrant expression of the CHFR prophase checkpoint gene in human B-cell non-Hodgkin lymphoma

Checkpoint with FHA and Ring Finger (CHFR) is a checkpoint protein that reportedly initiates a cell cycle delay in response to microtubule stress during prophase in mitosis, which has become an interesting target for understanding cancer pathogenesis. Recently, aberrant methylation of the CHFR gene associated with gene silencing has been reported in several cancers. In the present study, we examined the expression of CHFR in B-cell non-Hodgkin lymphoma (B-NHL) in vitro and in vivo. Our results showed that the expression level of CHFR mRNA and protein was reduced in B-NHL tissue samples and B cell lines. Furthermore, CHFR methylation was detected in 39 of 122 B-NHL patients, which was not found in noncancerous reactive hyperplasia of lymph node (RH) tissues. CHFR methylation correlated with the reduced expression of CHFR, high International Prognostic Index (IPI) scores and later pathologic Ann Arbor stages of B-NHL. Treatment with demethylation reagent, 5-Aza-dC, could eliminate the hypermethylation of CHFR, enhance CHFR expression and cell apoptosis and inhibit the cell proliferation of Raji cells, which could be induced by high expression of CHFR in Raji cells. Our results indicated that aberrant methylation of CHFR may be associated with the pathogenesis, progression for B-NHL, which might be a novel molecular marker as prognosis and treatment for B-NHL.

New insights into IL-12-mediated tumor suppression

During the past two decades, interleukin-12 (IL-12) has emerged as one of the most potent cytokines in mediating antitumor activity in a variety of preclinical models. Through pleiotropic effects on different immune cells that form the tumor microenvironment, IL-12 establishes a link between innate and adaptive immunity that involves different immune effector cells and cytokines depending on the type of tumor or the affected tissue. The robust antitumor response exerted by IL-12, however, has not yet been successfully translated into the clinics. The majority of clinical trials involving treatment with IL-12 failed to show sustained antitumor responses and were associated to toxic side effects. Here we discuss the therapeutic effects of IL-12 from preclinical to clinical studies, and will highlight promising strategies to take advantage of the antitumor activity of IL-12 while limiting adverse effects.

IL-10 secreting CD21⁺ B cells are present in jejunal Peyer's patches of sheep during fetal development

We recently reported a novel interleukin-10 (IL-10)-secreting CD21(+) B cell population in jejunal Peyer's patches (JPP) of sheep with a regulatory function (Bregs) suppressing Toll-like receptor 9 (TLR9)-induced cytokine responses. However, little is known about the development of these cells. Therefore, we investigate their existence in JPP cells from fetal and newborn lambs. CD21(+) B cells were purified from JPP cells by magnetic cell sorting and subsequently stimulated with the TLR9 agonist, CpG ODN (CpG oligodeoxynucleotide). Lymphocyte proliferative responses, cytokine production (IL-10, IL-12 and interferon-γ [INF-γ]) and antibody secretion were assayed. We found that fetal and neonatal CD21(+) B cells spontaneously secreted high levels of IL-10 regardless of CpG stimulation but that these cells did not produce any IL-12 or INF-γ upon stimulation with CpG. The observed responses are consistent with those previously reported for Bregs characterized in JPP of older lambs. Surprisingly, unlike in older lambs, fetal and neonatal JPP CD21(+) B cells proliferated in response to CpG stimulation. Our investigations of fetal and neonatal lambs provide evidence for the development of IL-10-secreting CD21(+) B cells in PPs prior to antigen exposure.

Enhancement of adaptive immunity to Neisseria gonorrhoeae by local intravaginal administration of microencapsulated interleukin 12

Gonorrhea remains one of the most frequent infectious diseases, and Neisseria gonorrhoeae is emerging as resistant to most available antibiotics, yet it does not induce a state of specific protective immunity against reinfection. Our recent studies have demonstrated that N. gonorrhoeae proactively suppresses host T-helper (Th) 1/Th2-mediated adaptive immune responses, which can be manipulated to generate protective immunity. Here we show that intravaginally administered interleukin 12 (IL-12) encapsulated in sustained-release polymer microspheres significantly enhanced both Th1 and humoral immune responses in a mouse model of genital gonococcal infection. Treatment of mice with IL-12 microspheres during gonococcal challenge led to faster clearance of infection and induced resistance to reinfection, with the generation of gonococcus-specific circulating immunoglobulin G and vaginal immunoglobulin A and G antibodies. These results suggest that local administration of microencapsulated IL-12 can serve as a novel therapeutic and prophylactic strategy against gonorrhea, with implications for the development of an effective vaccine.

Differential expression and function of human IL-12Rβ2 polymorphic variants

The receptor for interleukin-12, formed by IL-12Rβ1 and IL-12Rβ2, mediates the type I immune responses of various types of lymphocytes. Polymorphisms in IL12RB2, the gene encoding IL-12Rβ2, were reported to be associated with several immune related diseases, such as Crohn's disease. Because the IL23R and IL12RB2 genes are located in close proximity on the genome, the reported associations might also be attributable to linked polymorphisms in IL23R, which were found to be associated with immune related diseases as well. To clarify the role of IL-12Rβ2 in immune diseases, we investigated the functional consequences of thirteen amino acid substitutions in IL-12Rβ2. We developed a model with retroviral expression of IL-12Rβ2 in B cell lines. With the use of this model the expression and function of the variants was compared within the same genetic background. Four of the IL-12Rβ2 variants, N271Y, R313G, A604V and L808R showed reduced IL-12 responses compared to the wild type variant. Two of these are relatively common in some populations and may be used in future association studies to reveal a role for IL-12 in infectious and/or immune related diseases.

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.

Inflammatory signals direct expression of human IL12RB1 into multiple distinct isoforms

IL12RB1 is essential for human resistance to multiple intracellular pathogens, including Mycobacterium tuberculosis. In its absence, the proinflammatory effects of the extracellular cytokines IL-12 and IL-23 fail to occur, and intracellular bacterial growth goes unchecked. Given the recent observation that mouse leukocytes express more than one isoform from il12rb1, we examined whether primary human leukocytes similarly express more than one isoform from IL12RB1. We observed that human leukocytes express as many as 13 distinct isoforms, the relative levels of each being driven by inflammatory stimuli both in vitro and in vivo. Surprisingly, the most abundant isoform present before stimulation is a heretofore uncharacterized intracellular form of the IL-12R (termed "isoform 2") that presumably has limited contact with extracellular cytokine. After stimulation, primary PBMCs, including the CD4(+), CD8(+), and CD56(+) lineages contained therein, alter the splicing of IL12RB1 RNA to increase the relative abundance of isoform 1, which confers IL-12/IL-23 responsiveness. These data demonstrate both a posttranscriptional mechanism by which cells regulate their IL-12/IL-23 responsiveness, and that leukocytes primarily express IL12RB1 in an intracellular form located away from extracellular cytokine.

Unraveling effector functions of B cells during infection: the hidden world beyond antibody production

Antibodies made by B cells are critically important for immune protection to a variety of infectious agents. However, it is becoming increasingly clear that B cells do more than make antibodies and that B cells can both enhance and suppress immune responses. Furthermore, there is growing evidence that B cells modulate cellular immune responses by antibody dependent and independent mechanisms. Although we have a good understanding of the roles played by antibody- secreting effector B cells during immune responses, we know very little about the Ab independent "effector" functions of B cells in either health or disease. Given the recent data suggesting that B cells may contribute to autoimmune disease pathogenesis via an antibody independent mechanism and the increasing use of B cell depletion therapy in autoimmune patients, investigators are beginning to reassess the multiple roles for B cells during immune responses. In this article, we review data describing how B cells mediate protection to pathogens independently of antibody production. In particular, we will focus on the role that B cells play in facilitating dendritic cell and T cell interactions in lymph nodes, the importance of antigen-presenting B cells in sustaining effector T cell and T follicular helper responses to pathogens and the relevance of cytokine-producing effector and regulatory B cells in immune responses.

Molecular characterization, tissue distribution and expression analysis of interleukin-12 receptor β2 chain in sheep

Ovine β2 subunit of the interleukin (IL)-12 receptor (IL-12Rβ2) was cloned from mRNA preparation of mitogen-activated peripheral blood mononuclear cells (PBMCs). The complete coding sequence for ovine IL-12 Rβ2 was found to be 2586 nucleotides in length encoding 862-amino-acid residue protein. It showed 96.4% homology at the nucleotide level and 94.1% homology at the amino acid level with bovine IL-12 Rβ2. The ovine IL-12 Rβ2 subunit shares common structural and functional elements with their counterparts from the other species. Phylogenetic tree showed that ovine IL-12Rβ2 was clustered into the Artiodactyla group, together with those of cattle and pig, which was distinct from the other groups. Real-time RT-PCR was used to investigate expression of the IL-12Rβ2 in different tissues of sheep in order to determine the characterization of this receptor in tissue. Expression analysis showed that IL-12Rβ2 mRNA expression was detected at all the detected tissues with the exception of thymus.

Interferon-alpha triggers B cell effector 1 (Be1) commitment

B-cells can contribute to the pathogenesis of autoimmune diseases not only through auto-antibody secretion but also via cytokine production. Therapeutic depletion of B-cells influences the functions and maintenance of various T-cell subsets. The mechanisms governing the functional heterogeneity of B-cell subsets as cytokine-producing cells are poorly understood. B-cells can differentiate into two functionally polarized effectors, one (B-effector-1-cells) producing a Th-1-like cytokine pattern and the other (Be2) producing a Th-2-like pattern. IL-12 and IFN-γ play a key role in Be1 polarization, but the initial trigger of Be1 commitment is unclear. Type-I-interferons are produced early in the immune response and prime several processes involved in innate and adaptive responses. Here, we report that IFN-α triggers a signaling cascade in resting human naive B-cells, involving STAT4 and T-bet, two key IFN-γ gene imprinting factors. IFN-α primed naive B-cells for IFN-γ production and increased IFN-γ gene responsiveness to IL-12. IFN-γ continues this polarization by re-inducing T-bet and up-regulating IL-12Rβ2 expression. IFN-α and IFN-γ therefore pave the way for the action of IL-12. These results point to a coordinated action of IFN-α, IFN-γ and IL-12 in Be1 polarization of naive B-cells, and may provide new insights into the mechanisms by which type-I-interferons favor autoimmunity.

Programming the magnitude and persistence of antibody responses with innate immunity

Many successful vaccines induce persistent antibody responses that can last a lifetime. The mechanisms by which they do so remain unclear, but emerging evidence indicates that they activate dendritic cells via Toll-like receptors (TLRs). For example, the yellow fever vaccine YF-17D, one of the most successful empiric vaccines ever developed, activates dendritic cells via multiple TLRs to stimulate proinflammatory cytokines. Triggering specific combinations of TLRs in dendritic cells can induce synergistic production of cytokines, which results in enhanced T-cell responses, but its impact on antibody responses remain unknown. Learning the critical parameters of innate immunity that program such antibody responses remains a major challenge in vaccinology. Here we demonstrate that immunization of mice with synthetic nanoparticles containing antigens plus ligands that signal through TLR4 and TLR7 induces synergistic increases in antigen-specific, neutralizing antibodies compared to immunization with nanoparticles containing antigens plus a single TLR ligand. Consistent with this there was enhanced persistence of germinal centres and of plasma-cell responses, which persisted in the lymph nodes for >1.5 years. Surprisingly, there was no enhancement of the early short-lived plasma-cell response relative to that observed with single TLR ligands. Molecular profiling of activated B cells, isolated 7 days after immunization, indicated that there was early programming towards B-cell memory. Antibody responses were dependent on direct triggering of both TLRs on B cells and dendritic cells, as well as on T-cell help. Immunization protected completely against lethal avian and swine influenza virus strains in mice, and induced robust immunity against pandemic H1N1 influenza in rhesus macaques.

Interleukin-12 as an adjuvant for induction of protective antibody responses

Interleukin (IL)-12 is a pivotal cytokine that strongly stimulates Th1-associated cellular immunity. It is now recognized that IL-12 also activates humoral immunity to both T-dependent and T-independent antigens. This has let to considerable interest in exploiting IL-12 as a vaccine adjuvant for protection against various bacterial and viral pathogens, particularly in the lung. Studies examining the efficacy of IL-12-mediated effects on protective antibody response in the mouse model are summarized in this review.

IL-12 inhibits TNF-alpha induced osteoclastogenesis via a T cell-independent mechanism in vivo

It has been reported that TNF-alpha plays an important role in bone resorption in pathological conditions. IL-12, which is a T cell mediator, is also an important inflammatory cytokine. We previously reported that IL-12 induces apoptosis in bone marrow cells treated with TNF-alpha in vitro via an interaction between TNF-alpha-induced Fas and IL-12-induced Fas ligand (FasL), and that, as a result, osteoclastogenesis is inhibited. The purpose of this study was to investigate the effects of IL-12 on TNF-alpha-mediated osteoclastogenesis in vivo. We administered TNF-alpha with and without IL-12 into the supracalvaria in mice. The numbers of osteoclasts in the sutures in the calvaria were higher in mice administered TNF-alpha than in control mice not administered TNF-alpha. The numbers of osteoclasts in mice administered both TNF-alpha and IL-12 were lower than those in mice administered only TNF-alpha. Next, we determined the levels of mRNAs for cathepsin K and tartrate-resistant acid phosphatase (TRAP). mRNA levels were increased in mice administered TNF-alpha compared with control mice, but not in mice administered both TNF-alpha and IL-12. We also evaluated the amounts of tartrate-resistant acid phosphatase 5b (TRACP 5b) in mouse sera. The levels of TRACP 5b in mice administered TNF-alpha were higher than those in control mice. On the other hand, in mice administered both TNF-alpha and IL-12, the levels were lower than those in mice administered TNF-alpha alone. Fas and FasL expression levels were analyzed by real-time RT-PCR. The levels of Fas mRNA were increased in the calvaria of mice administered TNF-alpha compared with control mice, while those of FasL mRNAs were increased in the calvaria of mice administered IL-12. In TdT-mediated dUTP-biotin nick end-labeling (TUNEL) assays, many apoptotic cells were found in the sutures in the calvaria of mice administered both TNF-alpha and IL-12. IL-12 also inhibited TNF-alpha-induced osteoclastogenesis in mice whose T cells were blocked by anti-CD4 and anti-CD8 antibodies. These results suggest that IL-12 inhibits TNF-alpha-mediated osteoclastogenesis and induces apoptotic changes through an interaction between TNF-alpha-induced Fas and IL-12-induced FasL, in vivo, via a T cell-independent mechanism.

Interleukin-12 receptor beta2: from cytokine receptor to gatekeeper gene in human B-cell malignancies

Interleukin (IL) -12 is a cytokine that has been extensively characterized for its immunoregulatory activities. IL-12 binds to a heterodimeric receptor composed of the beta1 and beta2 chains. In this review article, we discuss recent findings on the expression and function of IL-12 receptor (IL-12R) in malignant B cells frozen at various stages of differentiation and in their normal counterparts. These studies, together with others performed in Il12rb2 knockout mice, have established the concept that the IL-12Rbeta2 gene is a gatekeeper from cancer. We will delineate three paradigms reflecting the differential expression of IL-12Rbeta2 in different groups of malignant B cells and discuss the therapeutic perspectives stemming from these studies.

Sequential priming with simian immunodeficiency virus (SIV) DNA vaccines, with or without encoded cytokines, and a replicating adenovirus-SIV recombinant followed by protein boosting does not control a pathogenic SIVmac251 mucosal challenge

Previously, combination DNA/nonreplicating adenovirus (Ad)- or poxvirus-vectored vaccines have strongly protected against SHIV(89.6P), DNAs expressing cytokines have modulated immunity elicited by DNA vaccines, and replication-competent Ad-recombinant priming and protein boosting has strongly protected against simian immunodeficiency virus (SIV) challenge. Here we evaluated a vaccine strategy composed of these promising components. Seven rhesus macaques per group were primed twice with multigenic SIV plasmid DNA with or without interleukin-12 (IL-12) DNA or IL-15 DNA. After a multigenic replicating Ad-SIV immunization, all groups received two booster immunizations with SIV gp140 and SIV Nef protein. Four control macaques received control DNA plasmids, empty Ad vector, and adjuvant. All vaccine components were immunogenic, but the cytokine DNAs had little effect. Macaques that received IL-15-DNA exhibited higher peak anti-Nef titers, a more rapid anti-Nef anamnestic response postchallenge, and expanded CD8(CM) T cells 2 weeks postchallenge compared to the DNA-only group. Other immune responses were indistinguishable between groups. Overall, no protection against intrarectal challenge with SIV(mac251) was observed, although immunized non-Mamu-A*01 macaques as a group exhibited a statistically significant 1-log decline in acute viremia compared to non-Mamu-A*01 controls. Possible factors contributing to the poor outcome include administration of cytokine DNAs to sites different from the Ad recombinants (intramuscular and intratracheal, respectively), too few DNA priming immunizations, a suboptimal DNA delivery method, failure to ensure delivery of SIV and cytokine plasmids to the same cell, and instability and short half-life of the IL-15 component. Future experiments should address these issues to determine if this combination approach is able to control a virulent SIV challenge.

Constitutive expression of IL-12R beta 2 on human multiple myeloma cells delineates a novel therapeutic target

The interleukin-12 (IL-12) receptor (R) B2 gene acts as tumor suppressor in human acute and chronic B-cell leukemias/lymphomas and IL-12rb2-deficient mice develop spontaneously localized plasmacytomas. With this background, we investigated the role of IL-12R beta 2 in multiple myeloma (MM) pathogenesis. Here we show the following: (1) IL-12R beta 2 was expressed in primary MM cells but down-regulated compared with normal polyclonal plasmablastic cells and plasma cells (PCs). IL-6 dampened IL-12R beta 2 expression on polyclonal plasmablastic cells and MM cells. (2) IL-12 reduced the proangiogenic activity of primary MM cells in vitro and decreased significantly (P = .001) the tumorigenicity of the NCI-H929 cell line in SCID/NOD mice by inhibiting cell proliferation and angiogenesis. The latter phenomenon was found to depend on abolished expression of a wide panel of proangiogenic genes and up-regulated expression of the antiangiogenic genes IFN-gamma, IFN-alpha, platelet factor-4, and TIMP-2. Inhibition of the angiogenic potential of primary MM cells was related to down-regulated expression of the proangiogenic genes CCL11, vascular endothelial-cadherin, CD13, and AKT and to up-regulation of an IFN-gamma-related antiangiogenic pathway. Thus, IL-12R beta 2 directly restrains MM cell growth, and targeting of IL-12 to tumor cells holds promise as new therapeutic strategy.

Priming of naive CD8+ T cells in the presence of IL-12 selectively enhances the survival of CD8+CD62Lhi cells and results in superior anti-tumor activity in a tolerogenic murine model

During the antigen-dependant activation process several subsets CD8+ T cells appear with different phenotypic and functional characteristics. Recent studies indicate that the state of T cell differentiation radically affects their ability to effectively respond to tumor challenge, with early effector CD8+ T (CD62Lhigh) cells having better anti-tumor activity. Thus strategies aimed at optimizing the generation of such subpopulations could significantly enhance the effectiveness of adoptive cell therapy (ACT) for cancer. In this study, we show that priming of naïve CD8+ T cells in the presence of IL-12 selectively rescued early CD8+ CD62L(hi) from activation induced cell death and resulted in the increased accumulation of this subset of CD8+ T cells. Furthermore, we demonstrated that IL-12 directly modulated the expression of CD62L on activated CD8+ T cells. When used for ACT, naïve CD8+ T cells primed in vitro in the presence of IL-12 showed superior anti-tumor activity toward B16 melanoma. Importantly, using the Pmel-1 model, priming pmel-1 cells in vitro with IL-12 reduced the state of functional tolerance associated with the non-mutated "self" tumor antigen gp100, as demonstrated by significant tumor responses in the absence of vaccination. Together, our results suggest that in vitro conditioning of naïve CD8+ T cells with IL-12 prior to ACT could significantly enhance their anti-tumor activity.

Aberrant methylation of IL-12Rbeta2 gene in lung adenocarcinoma cells is associated with unfavorable prognosis

BACKGROUND

Interleukin-12 receptor beta2 (IL-12Rbeta2) knock-out mice develop lung adenocarcinoma, and epigenetic silencing by CpG methylation leads to loss of this gene in B-cell malignancies. The aim of this study was to determine whether IL-12Rbeta2 methylation is a common feature in human lung cancer.

METHODS

We examined mRNA expression of IL-12Rbeta2 in lung cancer cell lines, and normal bronchial, and tracheal epithelial cells using RT-PCR, and we examined the methylation status of IL-12Rbeta2 in primary lung cancers.

RESULTS

Loss of expression was found in 10 of 13 (77%) NSCLC cell lines, and 2 of 5 (40%) SCLC cell lines compared with normal bronchial or tracheal cells. Treatment of 11 expression-negative cell lines with a demethylating agent restored expression in all cases. Aberrant methylation status of IL-12Rbeta2 gene was reversely concordant with its mRNA expression. IL-12Rbeta2 methylation was detected in 96 of 230 primary NSCLCs (42%) and 3 of 6 primary SCLCs (50%). IL-12Rbeta2 methylation correlated with poorer prognosis in lung adenocarcinomas (hazard ratio = 2.33, P = 0.0059).

CONCLUSIONS

We conclude that epigenetic silencing of IL-12Rbeta2 is a frequent event in lung cancers. Aberrant methylation of this gene seems to be a useful predictor of long-term outcome for adenocarcinoma of the lung.

Endogenous IL-12 triggers an antiangiogenic program in melanoma cells

The IL12RB2 gene acts as a tumor suppressor in human B cell malignancies. Indeed, Il12rb2 knockout (KO) mice develop spontaneously B cell tumors, but also lung epithelial tumors. This latter phenotype may be related to (i) impairment of host IL-12-mediated immunosurveillance and/or (ii) IL-12 inability to inhibit directly the growth of IL-12 unresponsive malignant cells. To address this issue, we transplanted IL-12R(+) B16 melanoma cells into syngeneic Il12rb2 KO mice with the following rationale: (i) these mice have severe defects in IFN-gamma production, as well as in cytotoxic T lymphocyte and natural killer cell cytotoxicity, and (ii) they produce but do not use IL-12 that can potentially bind to and target tumor cells only. Il12rb2 KO mice displayed higher endogenous serum levels of IL-12 and developed smaller B16 tumors than WT animals. These tumors showed reduced proliferation, increased apoptosis, and defective microvessel formation related to down-regulated expression of a set of proangiogenic genes previously unrelated to IL-12. Such effects depended on direct activity of endogenous IL-12 on tumor cells in KO mice, and hydrodynamic delivered IL-12 caused further reduced tumorigenicity of B16 cells in these mice. A previously undescribed mechanism of the IL-12 antitumor activity has been here identified and characterized.

Tumor mRNA-transfected dendritic cells stimulate the generation of CTL that recognize neuroblastoma-associated antigens and kill tumor cells: immunotherapeutic implications

Several observations suggest a potential role of T-cell-mediated immunity in the control of neuroblastoma (NB). However, the generation of NB-specific cytotoxic T lymphocytes (CTL) on T-cell priming with tumor mRNA-transfected dendritic cells (DC) has never been investigated before. In the present study, the feasibility of this strategy has been analyzed, both in healthy donors and in NB patients. Monocyte-derived DC were raised from three human leukocyte antigen (HLA) A2+ NB patients and seven HLA-A1+ or HLA-A2+ healthy donors transfected with mRNA from four NB cell lines and cocultured with autologous CD8+ lymphocytes. Expanded CTL expressed an effector/memory phenotype and a T cytotoxic 1-like profile of cytokine secretion. CTL specificity was demonstrated by interferon-gamma release on incubation with HLA-matched NB cell lines. The latter cell lines, but not autologous T-cell blasts, were lysed by CTL in an HLA-restricted manner. Cytotoxicity was found to involve the release of granzyme B. When tested for reactivity against NB-associated antigens, CTL from normal individuals recognized anaplastic lymphoma-associated kinase (ALK) and preferentially expressed antigen of melanoma (PRAME) peptides only, whereas patients' CTL reacted also to survivin, telomerase, and tyrosine hydroxylase peptides. This study demonstrates that DC transfected with NB mRNA induce the generation of patients' CTL specific for different NB-associated antigens, supporting the feasibility of NB T-cell immunotherapy.

A potential role for interleukin-18 in inhibition of the development of Cryptosporidium parvum

Accumulating evidence suggests that intestinal epithelial cells (IECs) constitutively express the immunoregulatory cytokine interleukin (IL)-18. IECs also serve as the host cell for the intracellular parasitic protozoan Cryptosporidium parvum. In the present study, C. parvum infection of a human enterocyte cell-line HCT-8 resulted in increased expression of IL-18 mRNA as measured by quantitative reverse transcription-polymerase chain reaction (RT-PCR). IL-18 protein was detected in control uninfected cells and following infection there was increased expression as measured by enzyme-linked immunosorbent assay (ELISA). Gene expression revealed the presence of the IL-18 receptor subunits not only in cell-lines but also in freshly isolated IECs, suggesting that IL-18-mediated signalling events may contribute to epithelial host defence during infection. Recombinant IL-18 inhibited intracellular development of the parasite in HCT-8 and HT-29 cells. Increased expression of bactericidal antibiotic peptides LL-37 and alpha-defensin 2 by IL-18 in HCT-8 and HT-29 cells may represent one mode of action by which this pluripotent cytokine aids in limiting the development of intracellular pathogens such as C. parvum in the gastrointestinal tract.

Tumor suppressor gene methylation in follicular lymphoma: a comprehensive review

Transcriptional silencing of tumor suppressor genes, associated with DNA methylation, is a common epigenetic event in hematologic malignancies. Although DNA hypermethylation of CpG islands is well described in acute leukemias and myelodysplastic syndromes, much less is known of the specific methylation changes that commonly occur in follicular B cell lymphomas. Earlier methylation studies of follicular lymphoma involved only cell lines; however there is a growing literature of methylation changes in primary human FL samples. Published studies of primary follicular lymphoma specimens have demonstrated that: androgen receptor, SHP1, and death-associated protein kinase genes are commonly methylated. By contrast, the cyclin dependent kinase inhibitors p15, p16, and p57 are uncommon epigenetic events in follicular lymphoma. Methylation of cyclin dependent kinase inhibitors is more common in high grade lymphomas, and may be an important step in the progression and transformation of follicular lymphoma. Further methylation studies in follicular lymphoma should investigate the prognostic and therapeutic significance of these epigenetic changes and investigate methylation of other genes. Finally, reactivation of methylated tumor suppressor genes through the use of hypomethylating agents is a promising and novel approach to the treatment of indolent and transformed follicular lymphomas.

Cooperative IFN-gamma production of mouse liver B cells and natural killer cells stimulated with lipopolysaccharide

BACKGROUND/AIMS

Although mouse liver contains a large population of B cells, little is known about how hepatic B cells respond to bacterial lipopolysaccharide (LPS).

METHODS

The cytokine and IgM productions of hepatic B cells were compared with those of splenic B cells. The effect of LPS-treated hepatic B cells on IFN-gamma production from co-cultured NK1.1+ cells was also examined by irradiation and transwell experiments.

RESULTS

Hepatic B cells stimulated with LPS produced substantial amounts of IFN-gamma and IL-12 but a small amount of IgM, while splenic B cells did not produce any of these cytokines but produced a large amount of IgM. The hepatic B cells expressed surface markers similar to those on spleen B cells but expressed more C-X-C chemokine receptor 3 than spleen B cells. Notably, depletion of B220+ cells from liver MNCs (but not from spleen MNCs) greatly decreased LPS-induced IFN-gamma production. Furthermore, LPS-treated hepatic B cells stimulated liver NK1.1+ cells to produce a remarkable amount of IFN-gamma, not only through their soluble factors but also through direct cell-cell contact.

CONCLUSIONS

Liver B cells may play an important role in the defense against gram-negative bacterial infections by inducing IFN-gamma production from liver NK 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.

Methylation of the IL-12Rbeta2 gene as novel tumor escape mechanism for pediatric B-acute lymphoblastic leukemia cells

Previous studies have shown that the interleukin-12 receptor beta2 (IL-12Rbeta2) gene is expressed in normal naive, germinal center and memory B cells but not in their malignant counterparts. The aim of this study was to investigate (i) whether the IL-12Rbeta2 gene is silenced in B-cell acute lymphoblastic leukemia (B-ALL) cells, and (ii) what the functional implications of such silencing for tumor growth are. Here, we show that although mature B cells expressed both chains of the IL-12R, normal pro-B and pre-B cells failed to express the IL-12Rbeta2 chain. Similarly, primary tumor cells from pediatric pro-B, early pre-B, and pre-B ALL (30 cases) did not express the IL-12Rbeta2 chain. IL-12Rbeta2 gene silencing in B-ALL was found to depend on methylation of a CpG island in exon 1. Such methylation was not detected in normal early B cells that when differentiated into mature B cells expressed the IL-12Rbeta2 gene. Detection of IL-12Rbeta2 mRNA and protein in the tumorigenic 697 pre-B-ALL cell line allowed to perform functional experiments in severe combined immunodeficient/nonobese diabetic mice receiving 697 cells with or without human recombinant IL-12 (hrIL-12). hrIL-12 administration reduced tumor growth and metastasis through antiproliferative and proapoptotic rather than antiangiogenic, activities. In conclusion, epigenetic silencing of the IL-12Rbeta2 gene represents a novel mechanism of tumor escape for B-ALL cells.

T Cell-Independent, TLR-Induced IL-12p70 Production in Primary Human Monocytes

IL-12p70 is a key cytokine for the induction of Th1 immune responses. IL-12p70 production in myeloid cells is thought to be strictly controlled by T cell help. In this work we demonstrate that primary human monocytes can produce IL-12p70 in the absence of T cell help. We show that human monocytes express TLR4 and TLR8 but lack TLR3 and TLR7 even after preincubation with type I IFN. Simultaneous stimulation of TLR4 and TLR8 induced IL-12p70 in primary human monocytes. IL-12p70 production in peripheral blood myeloid dendritic cells required combined stimulation of TLR7/8 ligands together with TLR4 or with TLR3 ligands. In the presence of T cell-derived IL-4, but not IFN-gamma, stimulation with TLR7/8 ligands was sufficient to stimulate IL-12p70 production. In monocytes, type I IFN was required but not sufficient to costimulate IL-12p70 induction by TLR8 ligation. Furthermore, TLR8 ligation inhibited LPS-induced IL-10 in monocytes, and LPS alone gained the ability to stimulate IL-12p70 in monocytes when the IL-10 receptor was blocked. Together, these results demonstrate that monocytes are licensed to synthesize IL-12p70 through type I IFN provided via the Toll/IL-1R domain-containing adaptor inducing IFN-beta pathway and the inhibition of IL-10, both provided by combined stimulation with TLR4 and TLR8 ligands, triggering a potent Th1 response before T cell help is established.