Modeling acute graft-versus-host disease (aGVHD) in murine bone marrow transplantation (BMT) models with MHC disparity

For more than 50years, hematopoietic stem cell transplantation (HSCT) has been the major curative therapy for hematological malignancies and genetic disorders, but its success is limited by the development of graft-versus-host disease (GVHD). GVHD represents a post-transplantation disorder representing the immune-mediated attack of transplant-derived T cells against recipient tissue finally leading to increased morbidity and mortality of the recipient. GVHD develops if donor and recipient are disparate in major or minor histocompatibility antigens (MHC, miHA). Most of the initial knowledge about the biology of GVHD is derived from murine bone marrow transplantation (BMT) models. Of course, GVHD mouse models do not reflect one to one the human situation, but they contribute significantly to our understanding how conditioning and danger signals activate the immune system, enlighten the role of individual molecules, e.g., cytokines, chemokines, death-inducing ligands, define the function of lymphocytes subpopulations for GVHD development and have significant impact on establishing new treatment and prevention strategies used in clinical HSCT. This chapter describes in detail the procedure of allogeneic BMT and the development of GVHD in two commonly used allogeneic murine BMT models (B6→B6.bm1, B6→B6D2F1) with different MHC disparities, which can be used as a basis for advanced studies of GVHD pathology or the development of new treatment strategies.

U-DCS: characterization of the first permanent human dendritic sarcoma cell line

A dendritic cell sarcoma cell line, U-DCS, was established from a dendritic cell sarcoma in a 53-year-old Caucasian male patient. Since its establishment, U-DCS has maintained stable phenotypic characteristics in vitro and has a doubling time of approximately 2 days under standard culture conditions. U-DCS is growing with typical dendritic cell morphology in tissue and expresses the dendritic cell sarcoma immunophenotypic markers S100 protein, MHCI, MHCII, and vimentin. Expression analysis revealed transcripts for the toll-like receptors TLR3, -4, -9 and DDX58 (RIG-I), but not for TLR2. U-DCS shows functional features of dendritic cells with the ability of phagocytosis and antigen-specific T cell stimulation. Karyotype-, CGH-, and mFISH analysis point to a chromosomal instability and a hypotetraploid karyotype with approximately 130 chromosomes. U-DCS is the first immortalized human dendritic cell sarcoma cell line and has some morphological and functional features of dendritic cells without dependency on growth factors.

Rapamycin-based graft-versus-host disease prophylaxis increases the immunosuppressivity of myeloid-derived suppressor cells without affecting T cells and anti-tumor cytotoxicity

The immunosuppressant rapamycin (RAPA) inhibits mammalian target of rapamycin (mTOR) functions and is applied after allogeneic bone marrow transplantation (BMT) to attenuate the development of graft‐versus‐host disease (GVHD), although the cellular targets of RAPA treatment are not well defined. Allogeneic T cells are the main drivers of GVHD, while immunoregulatory myeloid‐derived suppressor cells (MDSCs) were recently identified as potent disease inhibitors. In this study, we analyzed whether RAPA prevents the deleterious effects of allogeneic T cells or supports the immunosuppressive functions of MDSCs in a BMT model with major histocompatibility complex (MHC) classes I and II disparities. RAPA treatment efficiently attenuated clinical and histological GVHD and strongly decreased disease‐induced mortality. Although splenocyte numbers increased during RAPA treatment, the ratio of effector T cells to MDSCs was unaltered. However, RAPA treatment induced massive changes in the genomic landscape of MDSCs preferentially up‐regulating genes responsible for uptake or signal transduction of lipopeptides and lipoproteins. Most importantly, MDSCs from RAPA‐treated mice exhibited increased immunosuppressive potential, which was primarily inducible nitric oxide synthase (iNOS)‐dependent. Surprisingly, RAPA treatment had no impact on the genomic landscape of T cells, which was reflected by unchanged expression of activation and exhaustion markers and cytokine profiles in T cells from RAPA‐treated and untreated mice. Similarly, T cell cytotoxicity and the graft‐versus‐tumor effect were maintained as co‐transplanted tumor cells were efficiently eradicated, indicating that the immunosuppressant RAPA might be an attractive approach to strengthen the immunosuppressive function of MDSCs without affecting T cell immunity.

Aneuploidy-inducing gene knockdowns overlap with cancer mutations and identify Orp3 as a B-cell lymphoma suppressor

Aneuploidy can instigate tumorigenesis. However, mutations in genes that control chromosome segregation are rare in human tumors as these mutations reduce cell fitness. Screening experiments indicate that the knockdown of multiple classes of genes that are not directly involved in chromosome segregation can lead to aneuploidy induction. The possible contribution of these genes to cancer formation remains yet to be defined. Here we identified gene knockdowns that lead to an increase in aneuploidy in checkpoint-deficient human cancer cells. Computational analysis revealed that the identified genes overlap with recurrent mutations in human cancers. The knockdown of the three strongest selected candidate genes (ORP3, GJB3, and RXFP1) enhances the malignant transformation of human fibroblasts in culture. Furthermore, the knockout of Orp3 results in an aberrant expansion of lymphoid progenitor cells and a high penetrance formation of chromosomal instable, pauci-clonal B-cell lymphoma in aging mice. At pre-tumorous stages, lymphoid cells from the animals exhibit deregulated phospholipid metabolism and an aberrant induction of proliferation regulating pathways associating with increased aneuploidy in hematopoietic progenitor cells. Together, these results support the concept that aneuploidy-inducing gene deficiencies contribute to cellular transformation and carcinogenesis involving the deregulation of various molecular processes such as lipid metabolism, proliferation, and cell survival.

Clinical utility of a protein-based oncopanel in patients with end-stage head and neck cancer

Aim: In a prospective clinical initiative, we selected heavily pretreated head and neck carcinoma patients and assessed the clinical utility of a protein-based oncopanel for identification of potential targetable markers. Patients & methods: Tumor samples of 45 patients were evaluated using a 12-marker immunohistochemistry panel. The primary end point was the prevalence of potentially actionable markers. Results: At least one expressed marker in each case could be identified. We noted a high prevalence of EGFR (80%, 39/45) and MET (57.4%, 28/45). Three patients received oncopanel-based therapy with variable results. Conclusion: Despite the limited number of treated subjects, oncopanel analysis in end-stage head and neck cancer is operationally and technically feasible. Combination with targeted next generation sequencing might provide additional therapy options.

Block of NF-kB signaling accelerates MYC-driven hepatocellular carcinogenesis and modifies the tumor phenotype towards combined hepatocellular cholangiocarcinoma

Primary liver cancer ranks among the leading causes of cancer death worldwide. Risk factors are closely linked to inflammation, such as viral hepatitis and alcoholic as well as non-alcoholic steatohepatitis. Among the pathways involved in the pathogenesis of malignant liver tumors, dysregulation of NF-κB signaling plays a prominent role. It provides a link between inflammation and cancer. To examine the role of NF-κB in a MYC-induced model of hepatocellular carcinoma we deleted NEMO (IKKγ) specifically from hepatocytes. NEMO deletion accelerated tumor development and shortened survival, suggesting a tumor-suppressive function of NF-κB signaling. We observed increased proliferation, inflammation and fibrosis, as well as activation of MAPK and STAT signaling. Importantly, deletion of NEMO modified the tumor phenotype from hepatocellular carcinoma to combined hepatocellular cholangiocarcinoma. The intrahepatic cholangiocarcinoma tumor component showed increased expression of progenitor markers such as Sox9 and reduced expression of mature hepatic markers such as CPS1. In both cases tumorigenesis was reversible by turning off MYC expression. To our knowledge this is the first mouse model of combined hepatocellular cholangiocarcinoma and may provide insights into the development of this rare malignant tumor.

CK1α overexpression correlates with poor survival in colorectal cancer

Background

Colorectal cancer (CRC) is the fourth leading cause of cancer related deaths worldwide and prognosis in advanced tumor stage still remains poor. Since CK1 isoforms have been reported to be deregulated in several tumor entities CK1 has emerged as a novel drug target in cancer therapy. In this study we set out to investigate whether CK1α might have the potential to serve as prognostic marker.

Methods

CK1α RNA and protein expression levels in healthy and tumor tissue of CRC patients were analyzed using quantitative real-time PCR and Western Blot analysis, respectively. Prognostic relevance was investigated by correlating obtained CK1α expression levels with patients’ survival rate generating Kaplan-Meier survival plots.

Results

It could be shown that CK1α is overexpressed in colorectal tumor tissue compared to normal tissue and CK1α overexpression in tumor tissue correlates with poor survival in CRC patients. Results become more significant when only considering patients with high-grade tumors, as well as patients assigned to UICC II and UICC III stage. Furthermore, Cox regression analysis revealed that CK1α is an independent prognostic factor. In addition, tumors expressing decreased levels of the kinase reveal positive effects on overall survival when localized in the right colon compared to those in the left side.

Conclusion

In summary, this study provides evidence for the first time that CK1α RNA levels might serve as prognostic marker for CRC.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4019-0) contains supplementary material, which is available to authorized users.

CDK9 is a prognostic marker and therapeutic target in pancreatic cancer

Despite recent advances in diagnosis and therapy, prognosis of pancreatic cancer still remains very poor. Besides valid prognostic markers, novel therapeutic approaches are urgently needed. The family of cyclin-dependent kinases comprises 20 kinases which contribute to malignancy by promoting proliferation, migration, invasion, and apoptotic resistance of cancer cells. In this work, we investigated the role of CDK9 in pancreatic cancer. Immunohistochemical analysis of CDK9 expression in tumor and normal tissue of pancreatic cancer patients revealed an overexpression of CDK9 in pancreatic cancer tissue. In addition, high CDK9 expression in tumor tissue is associated with significantly shortened survival, especially in well-differentiated tumors. Moreover, the therapeutic potential of selective CDK9 inhibition on pancreatic cancer cells was evaluated by analysis of cell viability, long-term survival, and induction of apoptosis and characterized by western blotting and flow cytometry. Pharmacological CDK9 inhibition by SNS-032 drastically reduced cell viability in pancreatic cancer cells and potently suppressed long-term survival. Analyzing the mechanism of action revealed that CDK9 inhibition induced apoptosis and cell cycle arrest in a time-dependent manner by suppression of anti-apoptotic proteins. Furthermore, CDK9 inhibition potently enhances the therapeutic effect of chemotherapeutics in pancreatic cancer cells. In conclusion, we identified CDK9 as a negative prognostic marker in pancreatic cancer. Furthermore, pharmacological CDK9 inhibition is a novel and promising therapeutic approach for pancreatic cancer.

Canonical NF-κB signaling in hepatocytes acts as a tumor-suppressor in hepatitis B virus surface antigen-driven hepatocellular carcinoma by controlling the unfolded protein response

Chronic hepatitis B virus (HBV) infection remains the most common risk factor for hepatocellular carcinoma (HCC). Efficient suppression of HBV viremia and necroinflammation as a result of nucleos(t)ide analogue treatment is able to reduce HCC incidence; nevertheless, hepatocarcinogenesis can occur in the absence of active hepatitis, correlating with high HBV surface antigen (HBsAg) levels. Nuclear factor κB (NF-κB) is a central player in chronic inflammation and HCC development. However, in the absence of severe chronic inflammation, the role of NF-κB signaling in HCC development remains elusive. As a model of hepatocarcinogenesis driven by accumulation of HBV envelope polypeptides, HBsAg transgenic mice, which show no HBV-specific immune response, were crossed to animals with hepatocyte-specific inhibition of canonical NF-κB signaling. We detected prolonged, severe endoplasmic reticulum stress already at 20 weeks of age in NF-κB-deficient hepatocytes of HBsAg-expressing mice. The unfolded protein response regulator binding immunoglobulin protein/78-kDa glucose-regulated protein was down-regulated, activating transcription factor 6, and eIF2α were activated with subsequent overexpression of CCAAT/enhancer binding protein homologous protein. Notably, immune cell infiltrates and liver transaminases were unchanged. However, as a result of this increased cellular stress, insufficient hepatocyte proliferation due to G1 /S-phase cell cycle arrest with overexpression of p27 and emergence of ductular reactions was detected. This culminated in increased DNA damage already at 20 weeks of age and finally led to 100% HCC incidence due to NF-κB inhibition.

CONCLUSION

The role of canonical NF-κB signaling in HCC development depends on the mode of liver damage; in the case of HBsAg-driven hepatocarcinogenesis, NF-κB in hepatocytes acts as a critical tumor suppressor by augmenting the endoplasmic reticulum stress response.

Decreased CK1δ expression predicts prolonged survival in colorectal cancer patients

Cancers arising from the large intestine or rectum are called colorectal cancer (CRC) and represent the fourth leading cause of cancer-related death worldwide. Since casein kinase 1 (CK1) isoforms are involved in many cellular processes and have been reported to be deregulated in various tumor entities, CK1 has become an interesting drug target. In this study, we examined the potential of CK1δ expression levels in tumor tissue of CRC patients as a prognostic biomarker. We show by quantitative RNA expression analyses that decreased CK1δ expression levels in tumor tissue predict prolonged survival rates. Random sampling of CK1δ stained tumor tissue indicates that CK1δ gene expression corresponds with CK1δ protein expression. Especially in low grade (grade 1, grade 2) and in UICC II/III classified tumors decreased CK1δ RNA levels correlate with significantly improved survival rates when the tumor was located in the right colon. We furthermore found gender-specific differences within these subgroups, revealing most significant increase in overall survival rates in male patients with tumors in right colon expressing low levels of CK1δ RNA. Results become even clearer, when only male patients over 50 years were considered. Together, these findings support the assumption that CK1δ might be a prognostic biomarker for CRC thereby providing an interesting drug target for the development of new therapy concepts.

FOXO1 downregulation contributes to the oncogenic program of primary mediastinal B-cell lymphoma

Recently we have shown that the transcription factor FOXO1, highly expressed in B cells, is downregulated in classical Hodgkin lymphoma (cHL). As primary mediastinal B cell lymphoma (PMBL) has similarities with the cHL transcription program we investigated FOXO1 expression in this entity. By using immunohistochemistry we found that FOXO1 was absent or expressed at low levels in 19 of 20 primary PMBL cases. PMBL cell lines reproduce the low FOXO1 expression observed in primary cases. By analyzing gene expression profiling data we found that FOXO1 expression inversely correlated with JAK2 in PMBL cases. Targeting JAK2 activity by the small molecular weight inhibitor TG101348 resulted in upregulation of FOXO1 mRNA and protein expression in MedB-1 and U2940 cell lines, and the MYC inhibitor 10058-F4 increased FOXO1 mRNA in MedB-1 cells. Moreover, in MedB-1 cells FOXO1 expression was strongly upregulated by the inhibitor of DNA methylation 5-aza-2-deoxycytidine and by the histone deacetylase inhibitor trichostatin A. Since FOXO1 promoter was unmethylated, this effect is most likely indirect. FOXO1 activation in the FOXO1-negative MedB-1 cell line led to growth arrest and apoptosis, which was accompanied by repression of MYC and BCL2L1/BCLx_L. Thus, FOXO1 repression might contribute to the oncogenic program and phenotype of PMBL.

Nck adaptor proteins modulate differentiation and effector function of T cells

Understanding the molecular mechanisms regulating T cell reactivity is required for successful reprogramming of immune responses in medical conditions, characterized by dysfunctions of the immune system. Nck proteins are cytoplasmic adaptors mediating diverse cellular functions, including TCR signaling. By enhancing TCR signal strength, Nck proteins influence thymic selection and regulate the size and sensitivity of the peripheral T cell repertoire. Here, we investigated the contribution of Nck proteins to CD4(+) T cell differentiation and effector function using Nck.T(-/-) mice. Impaired GC formation and reduced Tfh were observed in Nck.T(-/-) mice after immunization with T cell-dependent antigens. Th2/Tfh-related cytokines, such as IL-4, IL-10, and IL-21, were decreased in Nck.T(-/-) mice T cells. Moreover, an increased susceptibility to cell death of Tfh cells in Nck.T(-/-) mice was associated with decreased levels of Akt phosphorylation. As a result of this dysregulation in Tfh cells of Nck.T(-/-) mice, we found impaired production and affinity maturation of antibodies against T cell-dependent antigens. Thus, Nck proteins not only participate in thymic selection and generation of the peripheral T cell repertoire but also are involved in the differentiation and effector functions of CD4(+) T cells.

CK1δ in lymphoma: gene expression and mutation analyses and validation of CK1δ kinase activity for therapeutic application

The prognosis of lymphoid neoplasms has improved considerably during the last decades. However, treatment response for some lymphoid neoplasms is still poor, indicating the need for new therapeutic approaches. One promising new strategy is the inhibition of kinases regulating key signal transduction pathways, which are of central importance in tumorigenesis. Kinases of the CK1 family may represent an attractive drug target since CK1 expression and/or activity are associated with the pathogenesis of malignant diseases. Over the last years efforts were taken to develop highly potent and selective CK1-specific inhibitor compounds and their therapeutic potential has now to be proved in pre-clinical trials. Therefore, we analyzed expression and mutational status of CK1δ in several cell lines representing established lymphoma entities, and also measured the mRNA expression level in primary lymphoma tissue as well as in non-neoplastic blood cells. For a selection of lymphoma cell lines we furthermore determined CK1δ kinase activity and demonstrated therapeutic potential of CK1-specific inhibitors as a putative therapeutic option in the treatment of lymphoid neoplasms.

Effects of altered expression and activity levels of CK1δ and ɛ on tumor growth and survival of colorectal cancer patients

Colorectal cancer (CRC) is the fourth leading cause of cancer related death worldwide due to high apoptotic resistance and metastatic potential. Because mutations as well as deregulation of CK1 isoforms contribute to tumor development and tumor progression, CK1 has become an interesting drug target. In this study we show that CK1 isoforms are differently expressed in colon tumor cell lines and that growth of these cell lines can be inhibited by CK1-specific inhibitors. Furthermore, expression of CK1δ and ɛ is changed in colorectal tumors compared to normal bowel epithelium, and high CK1ɛ expression levels significantly correlate with prolonged patients' survival. In addition to changes in CK1δ and ɛ expression, mutations within exon 3 of CK1δ were detected in colorectal tumors. These mutations influence ATP binding resulting in changes in kinetic parameters of CK1δ. Overexpression of these mutants in HT29 cells alters their ability to grow anchorage independently. Consistent with these results, these CK1δ mutants lead to differences in proliferation rate and tumor size in xenografts due to changes in gene expression, especially in genes involved in regulation of cell proliferation, cell cycle, and apoptosis. In summary, our results provide evidence that changes in the expression levels of CK1 isoforms in colorectal tumors correlate with patients' survival. Furthermore, CK1 mutants affect growth and proliferation of tumor cells and induce tumor growth in xenografts, leading to the assumption that CK1 isoforms provide interesting targets for the development of novel effective therapeutic concepts to treat colorectal cancer.

Hepatic activation of IKK/NFκB signaling induces liver fibrosis via macrophage-mediated chronic inflammation

Liver damage in humans is induced by various insults including alcohol abuse, hepatitis B/C virus infection, autoimmune or metabolic disorders and, when persistent, leads to development of liver fibrosis. Because the nuclear factor-κB (NF-κB) system is activated in response to several of these stresses, we hypothesized that NF-κB activation in hepatocytes may contribute to fibrosis development. To activate the NF-κB signaling pathway in a time- and cell-type-specific manner in the liver, we crossed transgenic mice carrying the tetracycline-responsive transactivator under the control of the liver activator protein promotor with transgenic mice carrying a constitutively active form of the Ikbkb gene (IKK2 protein [CAIKK2]). Double-transgenic mice displayed doxycycline-regulated CAIKK2 expression in hepatocytes. Removal of doxycycline at birth led to activation of NF-κB signaling, moderate liver damage, recruitment of inflammatory cells, hepatocyte proliferation, and ultimately to spontaneous liver fibrosis development. Microarray analysis revealed prominent up-regulation of chemokines and chemokine receptors and this induction was rapidly reversed after switching off the CAIKK2 expression. Turning off the transgene expression for 3 weeks reversed stellate cell activation but did not diminish liver fibrosis. The elimination of macrophages by clodronate-liposomes attenuated NF-κB-induced liver fibrosis in a liver-injury-independent manner.

CONCLUSION

Our results revealed that hepatic activation of IKK/NF-κB is sufficient to induce liver fibrosis by way of macrophage-mediated chronic inflammation. Therefore, agents controlling the hepatic NF-κB system represent attractive therapeutic tools to prevent fibrosis development in multiple chronic liver diseases.

Impaired CK1 delta activity attenuates SV40-induced cellular transformation in vitro and mouse mammary carcinogenesis in vivo

Simian virus 40 (SV40) is a powerful tool to study cellular transformation in vitro, as well as tumor development and progression in vivo. Various cellular kinases, among them members of the CK1 family, play an important role in modulating the transforming activity of SV40, including the transforming activity of T-Ag, the major transforming protein of SV40, itself. Here we characterized the effects of mutant CK1δ variants with impaired kinase activity on SV40-induced cell transformation in vitro, and on SV40-induced mammary carcinogenesis in vivo in a transgenic/bi-transgenic mouse model. CK1δ mutants exhibited a reduced kinase activity compared to wtCK1δ in in vitro kinase assays. Molecular modeling studies suggested that mutation N172D, located within the substrate binding region, is mainly responsible for impaired mutCK1δ activity. When stably over-expressed in maximal transformed SV-52 cells, CK1δ mutants induced reversion to a minimal transformed phenotype by dominant-negative interference with endogenous wtCK1δ. To characterize the effects of CK1δ on SV40-induced mammary carcinogenesis, we generated transgenic mice expressing mutant CK1δ under the control of the whey acidic protein (WAP) gene promoter, and crossed them with SV40 transgenic WAP-T-antigen (WAP-T) mice. Both WAP-T mice as well as WAP-mutCK1δ/WAP-T bi-transgenic mice developed breast cancer. However, tumor incidence was lower and life span was significantly longer in WAP-mutCK1δ/WAP-T bi-transgenic animals. The reduced CK1δ activity did not affect early lesion formation during tumorigenesis, suggesting that impaired CK1δ activity reduces the probability for outgrowth of in situ carcinomas to invasive carcinomas. The different tumorigenic potential of SV40 in WAP-T and WAP-mutCK1δ/WAP-T tumors was also reflected by a significantly different expression of various genes known to be involved in tumor progression, specifically of those involved in wnt-signaling and DNA repair. Our data show that inactivating mutations in CK1δ impair SV40-induced cellular transformation in vitro and mouse mammary carcinogenesis in vivo.

In vitro-established alloantigen-specific CD8+ CTLs mediate graft-versus-tumor activity in the absence of graft-versus-host disease

Mature donor-derived T cells in allogeneic bone marrow (BM) transplants mediate the graft-versus-tumor (GVT) effect by recognizing alloantigens on leukemic cells. However, alloantigen reactivity towards non-malignant tissues also induces graft-versus-host disease (GVHD). Defining T-cell subpopulations that mediate the GVT effect in the absence of GVHD induction remains a major challenge in allogeneic BM transplantation. In this study, we show that in vitro-generated alloantigen-specific CD8(+) cytotoxic T cells (CTLs) established by weekly stimulation with alloantigen-expressing antigen-presenting cells did not induce GVHD in two major histocompatibility complex-mismatched BM transplantation models, where induction of lethal GVHD is dependent on the presence of either CD4(+) or CD8(+) T cells. Despite their strong alloantigen specificity, transplantation of CTLs did not induce the expression of GVHD-associated cytokines IFN-γ and TNF-α or clinical or histological signs of GVHD, and lead to a survival rate of above 90%. However, transplantation of unstimulated CD8(+) T cells, which were not primed by the alloantigen in vitro, induced GVHD in both the transplantation models. Although CTLs were impaired in GVHD induction, they efficiently eradicated Bcr-Abl-transformed B-cell leukemias or mastocytomas. Thus, in vitro-derived CTLs might be useful for optimizing anti-tumor therapy in the absence of GVHD induction.

Analysis of cell type-specific expression of CK1 epsilon in various tissues of young adult BALB/c Mice and in mammary tumors of SV40 T-Ag-transgenic mice

Casein kinase 1 epsilon (CK1epsilon) is involved in various cellular processes, including cell growth, differentiation, and apoptosis, vesicle transport, and control of the circadian rhythm. Deregulation of CK1epsilon has been linked to neurodegenerative diseases and cancer. To better understand the cell type-specific functions of CK1epsilon, we determined its localization by immunhistochemistry in tissues of healthy, young adult BALB/c mice and in mammary tumors of SV40 T-antigen-transgenic mice. CK1epsilon expression was found to be highly regulated in normal tissues of endodermal, mesodermal, and ectodermal origin and in neoplastic tissue of mammary cancer. The data presented here give an overview of CK1epsilon reactivity in different organs under normal conditions and outline changes in its expression in mammary carcinomas. Our data suggest a cell/organ type-specific function of CK1epsilon and indicate that tumorigenic conversion of mammary glands in SV40 T-antigen-transgenic mice leads to downregulation of CK1epsilon. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

IL-22-dependent attenuation of T cell-dependent (ConA) hepatitis in herpes virus entry mediator deficiency

Coinhibitors and costimulators control intrahepatic T cell responses that trigger acute hepatitis. We used the ConA-induced hepatitis model in the mouse to test if the coinhibitor herpes virus entry mediator (HVEM) modulates hepatitis-inducing T cell responses. Compared with ConA-injected, wild-type (wt) C57BL/6 (B6) mice, HVEM-deficient (HVEM(-/-)) B6 mice showed lower serum transaminase levels and lower proinflammatory IFN-gamma, but higher protective IL-22 serum levels and an attenuated liver histopathology. The liver type I invariant NKT cell population that initiates acute hepatitis in this model was reduced in HVEM(-/-) mice but their surface phenotype was similar to that of untreated or ConA-treated wt controls. In response to mitogen injection, liver invariant NKT cells from HVEM(-/-) B6 mice produced in vivo more IL-22 but lower amounts of IFN-gamma and IL-4 than wt controls. Bone marrow chimeras showed that HVEM deficiency of the liver nonparenchymal cell population, but not of the parenchymal cell population, mediated the attenuated course of the dendritic cell- and T cell-dependent ConA hepatitis. IL-22 is produced more efficiently by liver NKT cells from HVEM(-/-) than from wt mice, and its Ab-mediated neutralization of IL-22 aggravated the course of hepatitis in wt and HVEM(-/-) mice. Hence, HVEM expression promotes pathogenic, proinflammatory Th1 responses but down-modulates protective IL-22 responses of T cells in this model of acute hepatitis.

IL-20 receptor 2 signaling down-regulates antigen-specific T cell responses

The recently described cytokines IL-19, IL-20, and IL-24 share structural homology with IL-10 and are therefore classified as members of the IL-10 family of cytokines. Although it has long been speculated that signaling by their heterodimeric receptor complexes (IL-20R1/IL-20R2 and IL-22R/IL-20R2) influences immunological processes, the target cells for this group of cytokines are still unclear. By generating a knockout mouse strain deficient for the common IL-20R beta-chain (IL-20R2), we show that IFN-gamma and IL-2 secretion is significantly elevated after stimulation of IL-20R2-/--deficient CD8 and CD4 T cells with Con A or anti-CD3/CD28 in vitro. IL-10 secretion by activated IL-20R2-/- CD4 cells was diminished. Consistent with our in vitro results, significantly more Ag-specific CD8 IFN-gamma+ and CD4 IFN-gamma+ T cells developed to locally applied DNA vaccines in IL-20R2-deficient mice. In a T cell-dependent model of contact hypersensitivity, IL-20R2 knockout mice were more sensitive to the contact allergen trinitro-chloro-benzene. Thus, IL-20R2 signaling directly regulates CD8 and CD4 T cell answers in vitro and in vivo. For the first time, we provide evidence that IL-19, IL-20, and IL-24 are part of a signaling network that normally down-modulates T cell responses in mice.

Immunohistochemical characterisation of cell-type specific expression of CK1delta in various tissues of young adult BALB/c mice

BACKGROUND

Casein kinase 1 delta (CK1delta) phosphorylates many key proteins playing important roles in such biological processes as cell growth, differentiation, apoptosis, circadian rhythm and vesicle transport. Furthermore, deregulation of CK1delta has been linked to neurodegenerative diseases and cancer. In this study, the cell specific distribution of CK1delta in various tissues and organs of young adult BALB/c mice was analysed by immunohistochemistry.

METHODOLOGY/PRINCIPAL FINDINGS

Immunohistochemical staining of CK1delta was performed using three different antibodies against CK1delta. A high expression of CK1delta was found in a variety of tissues and organ systems and in several cell types of endodermal, mesodermal and ectodermal origin.

CONCLUSIONS

These results give an overview of the cell-type specific expression of CK1delta in different organs under normal conditions. Thus, they provide evidence for possible cell-type specific functions of CK1delta, where CK1delta can interact with and modulate the activity of key regulator proteins by site directed phosphorylation. Furthermore, they provide the basis for future analyses of CK1delta in these tissues.

Anti-apoptotic and growth-stimulatory functions of CK1 delta and epsilon in ductal adenocarcinoma of the pancreas are inhibited by IC261 in vitro and in vivo

BACKGROUND

Pancreatic ductal adenocarcinomas (PDACs) are highly resistant to treatment due to changes in various signalling pathways. CK1 isoforms play important regulatory roles in these pathways.

AIMS

We analysed the expression levels of CK1 delta and epsilon (CK1delta/in) in pancreatic tumour cells in order to validate the effects of CK1 inhibition by 3-[2,4,6-(trimethoxyphenyl)methylidenyl]-indolin-2-one (IC261) on their proliferation and sensitivity to anti-CD95 and gemcitabine.

METHODS

CK1delta/in expression levels were investigated by using western blotting and immunohistochemistry. Cell death was analysed by FACS analysis. Gene expression was assessed by real-time PCR and western blotting. The putative anti-tumoral effects of IC261 were tested in vivo in a subcutaneous mouse xenotransplantation model for pancreatic cancer.

RESULTS

We found that CK1delta/in are highly expressed in pancreatic tumour cell lines and in higher graded PDACs. Inhibition of CK1delta/in by IC261 reduced pancreatic tumour cell growth in vitro and in vivo. Moreover, IC261 decreased the expression levels of several anti-apoptotic proteins and sensitised cells to CD95-mediated apoptosis. However, IC261 did not enhance gemcitabine-mediated cell death either in vitro or in vivo.

CONCLUSIONS

Targeting CK1 isoforms by IC261 influences both pancreatic tumour cell growth and apoptosis sensitivity in vitro and the growth of induced tumours in vivo, thus providing a promising new strategy for the treatment of pancreatic tumours.

Commensal gut flora drives the expansion of proinflammatory CD4 T cells in the colonic lamina propria under normal and inflammatory conditions

We tested in B6 mice whether the local expansion of CD4 T cells producing proinflammatory cytokines including IL-17 (Th17 cells) in the colonic lamina propria (cLP) depends on the commensal microflora. High numbers of CD4 Th17 cells were found in the lamina propria of the ileum and colon but not the duodenum, jejunum, mesenteric lymph nodes, spleen, or liver of specific pathogen-free (SPF) mice. The microflora is required for the accumulation of cytokine (IL-17, IFN-gamma, TNF-alpha, IL-10)-producing CD4 T cells in the cLP because only low numbers of cytokine-producing cLP CD4 T cells were found in syngeneic (age- and sex-matched) germfree mice. The fraction of cLP Th17 cells was higher in (type I and type II) IFN- but not IL-4- or IL-12p40-deficient SPF congenics. cLP CD4 Th17 cells produce IL-17 but not IFN-gamma, TNF-alpha, IL-4, or IL-10. cLP CD4 Th17 cells accumulate locally in colitis induced by adoptive transfer of IFN-gamma+/+ or IFN-gamma-/- CD4 T cells into congenic SPF (but not germfree) RAG-/- hosts. In this colitis model, cLP CD4 T cells that "spontaneously" produce IL-17 progressively increase in number in the inflamed cLP, and increasing serum IL-17 levels appear as the disease progresses. Commensal bacteria-driven, local expansion of cLP CD4 Th17 cells may contribute to the pathogenesis of this inflammatory bowel disease.

Target Sequence Accessibility Limits Activation-Induced Cytidine Deaminase Activity in Primary Mediastinal B-Cell Lymphoma

Activation-induced cytidine deaminase (AID) initiates somatic hypermutation (SHM) and class switch recombination (CSR) in activated B lymphocytes and is potentially implicated in genomic instability of B-cell malignancies. For unknown reasons, B-cell neoplasms often lack SHM and CSR in spite of high AID expression. Here, we show that primary mediastinal B-cell lymphoma (PMBL), an immunoglobulin (Ig)-negative lymphoma that possesses hypermutated, class-switched Ig genes, expresses high levels of AID with an intact primary structure but does not do CSR in 14 of 16 cases analyzed. Absence of CSR coincided with low Ig germ-line transcription, whereas high level germ-line transcription was observed only in those two cases with active CSR. Interleukin-4/CD40L costimulation induced CSR and a marked up-regulation of germ-line transcription in the PMBL-derived cell line MedB-1. In the PMBL cell line Karpas 1106P, CSR was not inducible and germ-line transcription remained low on stimulation. However, Karpas 1106P, but not MedB-1, had ongoing SHM of the Ig gene and BCL6. These genes were transcribed in Karpas 1106P, whereas transcription was undetectable or low in MedB-1 cells. Thus, accessibility of the target sequences seems to be a major limiting factor for AID-dependent somatic gene diversification in PMBL.

Foxp3-expressing CD103+ regulatory T cells accumulate in dendritic cell aggregates of the colonic mucosa in murine transfer colitis

Little is known of the anatomical compartmentalization of colitogenic or regulatory T-cell responses in the murine transfer colitis model. Therefore, we analyzed the putative function of large intestinal dendritic cell (DC) aggregates, to which donor CD4+ T cells selectively home before colitis becomes manifest. The co-stimulatory molecules MHC-II, CD40, CD80, and CD86 were expressed in DC aggregates. IL-23 was primarily absent from DC aggregates at all stages of disease but was expressed at high levels in the severely inflamed lamina propria. Interferon-gamma was up-regulated in the lamina propria during early and advanced disease, whereas in DC aggregates it was detectable to a significant degree only in fully developed colitis. In contrast, Foxp3, a marker of regulatory T cells, was expressed in DC aggregates on T-cell transfer, coinciding with the appearance of CD103+ CD25- T cells in these clusters. Foxp3 was enriched in the CD103+ T-cell fraction isolated from the lamina propria of diseased mice. T-cell grafts depleted of CD103+ T cells generated similar numbers of colonic CD103+ T cells as unfractionated T cells. We conclude that DC aggregates are structures involved in the expansion and/or differentiation of CD103+ CD25- CD4+ Foxp3-expressing regulatory T cells.

AID expression identifies interfollicular large B cells as putative precursors of mature B-cell malignancies

Neoplastic transformation of mature B cells can be triggered by class-switch recombination of the immunoglobulin gene, which aberrantly targets a protooncogene and promotes translocation. Class-switch recombination is initiated by the B-cell-specific protein activation-induced cytidine deaminase (AID). Using immunohistochemistry with a newly generated monoclonal antibody and quantitative reverse-transcription-polymerase chain reaction (RT-PCR) on microdissected tissue from lymph node, tonsil, and thymus, we demonstrate that AID expression is found in secondary lymphoid organs outside germinal centers and in the thymic medulla at substantial levels. This is accompanied by the presence of circle transcripts, indicating class-switch recombination to be active at these sites. The dominant AID-expressing cell population outside germinal centers displays cytomorphologic properties corresponding to those that define the recently characterized interfollicular large B-cell subset. These findings indicate that interfollicular large B cells and AID-expressing B lymphocytes of the thymic medulla could give rise to mature B-cell malignancies. (Blood. 2006;107:2470-2473)

Epigenetic processes play a major role in B-cell-specific gene silencing in classical Hodgkin lymphoma

Many B-lineage-specific genes are down-regulated in Hodgkin and Reed-Sternberg (HRS) cells of classical Hodgkin lymphoma (cHL). We investigated the involvement of epigenetic modifications in gene silencing in cHL cell lines and in microdissected primary HRS cells. We assessed the expression and methylation status of CD19, CD20, CD79B, SYK, PU.1, BOB.1/OBF.1, BCMA, and LCK, all of which are typically down-regulated in cHL. We could reactivate gene expression in cHL cell lines with the DNA demethylating agent 5-aza-deoxycytidine (5-aza-dC). Using methylation-specific polymerase chain reaction (MSP), bisulfite genomic sequencing, and digestion with methylation-sensitive endonuclease followed by polymerase chain reaction (PCR), we determined the methylation status of promoter regions of PU.1, BOB.1/OBF.1, CD19, SYK, and CD79B. Down-regulation of transcription typically correlated with hypermethylation. Using bisulfite genomic sequencing we found that in microdissected HRS cells of primary cHL SYK, BOB.1/OBF.1, and CD79B promoters were also hypermethylated. Ectopic expression of both Oct2 and PU.1 in a cHL cell line potentiated endogenous PU.1 and SYK expression after 5-aza-dC treatment. These observations indicate that silencing of the B-cell-specific genes in cHL may be the consequence of a compromised regulatory network where down-regulation of a few master transcription factors results in silencing of numerous genes.

Biallelic deletion within 16p13.13 includingSOCS-1in Karpas1106P mediastinal B-cell lymphoma line is associated with delayed degradation of JAK2 protein

Activity of Janus kinase 2 (JAK2) in the JAK2/STAT5 signaling pathway is critically controlled by suppressor of cytokine signaling-1 (SOCS-1). We have previously shown that SOCS-1 is biallelically mutated in the primary mediastinal B-cell lymphoma (PMBL) cell line MedB-1, resulting in impaired JAK2 degradation and sustained phospho-JAK2 action. SOCS-1 is frequently mutated in PMBL tumor primaries. Here, we report that the PMBL cell line Karpas1106P has a biallelic deletion of the SOCS-1 region on chromosome 16p13.13. By fluorescence in situ hybridization and microsatellite analysis, this deletion was narrowed down to a range of 650 kb to 1.48 Mb. Like MedB-1, Karpas1106P harbors gains of the JAK2 gene on chromosomal region 9p24 and elevated levels of JAK2 mRNA. Nevertheless, JAK2 protein was not increased but constitutively phosphorylated in Karpas1106P cells. In analogy to MedB-1 cells, Karpas1106P cells exhibited a retarded degradation of de novo synthesized JAK2 protein revealed by pulse/chase experiments. Therefore, we conclude that loss of SOCS-1 function either by mutation or by the complete deletion of the gene plays an important role in the dysregulation of JAK/STAT signaling in Karpas1106P and PMBL.

Report: workshop on mediastinal grey zone lymphoma

There are several indications that classical Hodgkin lymphoma (cHL) and at least a proportion of cases of Primary Mediastinal B cell Lymphoma (PMBL) are derived from B cells at similar stages of differentiation and share common pathogenic mechanisms. The first indication was the existence of mediastinal grey zone lymphomas as identified in the 4th International Symposium on HL, with clinical, histological and immunohistochemical features intermediate between cHL and PMBL. Second, both tumor types resemble a cell that is developmentally situated in-between the germinal center reaction and a plasma cell. Third, cHL and PMBL were found to have similar gene expression profiles, including the lack of immunoglobulin expression and low levels of B cell receptor signalling molecules, and the secretion of molecules like the chemokine TARC and the prominent expression of IL-13 receptors. Fourth, both entities were found to have common genomic aberrancies, notably in 2p15 and 9p24, the sites of the REL oncogene and the tyrosine kinase gene JAK2, respectively. Further comparison of both lymphoma types may provide further insight in the pathogenic mechanisms and allow the design of diagnostic algorithms to sort out the small number of so-called mediastinal grey zone lymphomas, that appear to be intermediate between PMBL and cHL.

Downregulation of internal enhancer activity contributes to abnormally low immunoglobulin expression in the MedB-1 mediastinal B-cell lymphoma cell line

Primary mediastinal B-cell lymphoma (PMBL) is a highly aggressive tumour with a unique pattern of clinical, morphological, immunological and genetic features distinct from other diffuse large B-cell lymphomas. PMBLs are characterized by a mature B-cell phenotype, but they typically lack immunoglobulin (Ig) gene expression. The PMBL cell line MedB-1 shares many characteristic properties of the primary tumour, including low-level Ig production despite a functionally rearranged IgVH gene and absence of 'crippling' mutations. In this study, a search was undertaken for reasons for downregulated Ig expression. Similar levels of the B-cell-specific transcription factors BOB.1/OBF.1 and PU.1 were found in MedB-1 cells to those in the Ig-producing UM-1 lymphoblastoid cell line. However, MedB-1 lacked the Oct2 transcription factor. Reporter assays showed that Ig-type promoters were active in MedB-1 cells. In contrast, activity of the intronic heavy chain enhancer was dramatically reduced. Ectopic expression of Oct2 was able partially to restore enhancer activity but transcription from the endogenous IgVH gene could not be rescued. Therefore, the role of epigenetic factors in the downregulation of Ig was investigated. Methylated histone 3 lysine 9, a reliable marker of chromatin silencing, was not detected in MedB-1 promoter and enhancer regions. Inhibition of DNA methyltransferase and of histone deacetylases also did not reactivate Ig production. These data suggest the existence of alternative mechanisms of Ig inhibition in MedB-1 cells, different from chromatin silencing and the lack of Oct2.

[Biallelic mutation of SOCS-1 impairs JAK2 degradation and sustains phospho-JAK2 action in MedB-1 mediastinal lymphoma line]

Primary mediastinal B-cell lymphoma (PMBL) is a well-defined subtype of diffuse large B-cell lymphoma. Molecular cytogenetics revealed frequent gains of 9 p24. JAK2, mapping in this region, is presently regarded as a candidate oncogene since expression profiling showed high JAK2 transcript levels and JAK2 was found to be constitutively phosphorylated in mediastinal B-cell lymphomas. We confirm that in the MedB-1 mediastinal B-cell line, harbouring a trisomy 9, JAK2 transcription is elevated and the product is highly phosphorylated. However, JAK2 is not over-expressed at the protein level. On top, JAK2 protein turnover is even delayed. This unexpected finding coincides with a biallelic mutation of the SOCS-1 gene in this cell, which abrogates SOCS box function of the protein. Ectopic expression of wt-SOCS-1 in MedB-1 leads to growth arrest, dramatic reduction of phospho-JAK2 and its downstream partner phospho-STAT5. We conclude that, in MedB-1, action of phospho-JAK2 is sustained due to defective SOCS-1. Hence, SOCS-1 qualifies as a novel tumor suppressor. Of note, the SOCS-1 mutations are also present in the parental tumor of MedB-1 and were detected in 9 of 20 PMBL.

Biallelic mutation of SOCS-1 impairs JAK2 degradation and sustains phospho-JAK2 action in the MedB-1 mediastinal lymphoma line

Primary mediastinal B-cell lymphoma (PMBL) is a well-defined subtype of diffuse large B-cell lymphoma. Molecular cytogenetics revealed frequent gains of 9p24. JAK2, mapping in this region, is presently regarded as a candidate oncogene because expression profiling showed high Janus kinase-2 (JAK2) transcript levels and JAK2 was found to be constitutively phosphorylated in mediastinal B-cell lymphomas. We confirm that in the MedB-1 mediastinal B-cell line, harboring a trisomy 9, JAK2 transcription is elevated and the product is highly phosphorylated. However, JAK2 is not overexpressed at the protein level. On top, JAK2 protein turnover is even delayed. This unexpected finding coincides with a biallelic mutation of the suppressor of cytokine signaling-1 (SOCS-1) gene in this cell, which abrogates SOCS box function of the protein. Ectopic expression of wild-type (wt) SOCS-1 in MedB-1 leads to growth arrest and dramatic reduction of phospho-JAK2 and its downstream partner phospho-signal transducer and activator of transcription-5 (phospho-STAT5). Ultimately, the target gene cyclin D1 is repressed in transfectants while RB1, which is silenced in MedB-1, is induced. We conclude that, in MedB-1, action of phospho-JAK2 is sustained due to defective SOCS-1. Hence, SOCS-1 qualifies as a novel tumor suppressor. Of note, SOCS-1 mutations are also present in the parental tumor of MedB-1 and were detected in 9 of 20 PMBLs.

Epigenetic silencing of the immunoglobulin heavy-chain gene in classical Hodgkin lymphoma-derived cell lines contributes to the loss of immunoglobulin expression

Immunoglobulin production is impaired in Hodgkin and Reed-Sternberg (HRS) cells of classical Hodgkin lymphoma (cHL) in spite of functional clonal rearrangements. The presence of "crippling" mutations in coding and regulatory regions, as well as down-regulation of B-cell-specific transcription factors, has been suggested as a potential reason for the lack of immunoglobulin (Ig) chain gene transcription. We have investigated the impact of epigenetic silencing in suppressing Ig heavy (H)-chain expression. Chromatin immunoprecipitation (ChIP) was used to analyze transcription factor binding to octamer motifs present in the IgH regulatory regions. Transcription factors were bound to these motifs in control cell lines, however, they were absent in the cHL-derived cell lines KMH2, L1236, and L428. Ectopic expression of octamer-binding transcription factor (Oct2) and/or B-cell Oct binding protein/Oct-binding factor (BOB.1/OBF.1) did not result in any measurable binding to these sites. Increased histone 3 Lysine 9 (H3-K9) methylation was observed in the promoter region of the IgH locus in L428 and L1236 cells. This is a typical feature of heterochromatic, transcriptionally silent regions. Treatment of cHL-derived cell lines with the DNA demethylating agent 5-aza-2'-deoxycytidine (5-aza-dC) partially reactivated IgH transcription and affected chromatin modifications. Our results suggest an important role of epigenetic silencing in the inhibition of IgH transcription in HRS cells.

MHC class II-independent CD25+ CD4+ CD8alpha beta+ alpha beta T cells attenuate CD4+ T cell-induced transfer colitis

CD4+ alpha beta T cell populations that develop in mice deficient in MHC class II (through 'knockout' of either the Aalpha, or the Abeta chain of the I-A(b) molecule) comprise a major 'single-positive' (SP) CD4+ CD8- subset (60-90%) and a minor 'double-positive' (DP) CD4+ CD8alpha beta+ subset (10-40%). Many DP T cells found in spleen, mesenteric lymph nodes (MLN) and colonic lamina propria (cLP) express CD25, CD103 and Foxp3. Adoptive transfer of SP but not DP T cells from Aalpha(-/-) or Abeta(-/-) B6 mice into congenic RAG(-/-) hosts induces colitis. Transfer of SP T cells repopulates the host with only SP T cells; transfer of DP T cells repopulates the host with DP and SP T cells. Anti-CD25 antibody treatment of mice transplanted with DP T cells induces severe, lethal colitis; anti-CD25 antibody treatment of mice transplanted with SP T cells further aggravates the course of severe colitis. Hence, regulatory CD25+ T cells within (or developing from) the DP T cell population of MHC class II-deficient mice control the colitogenic potential of CD25- CD4+ T cells.

Hepatic dendritic cell subsets in the mouse

The CD11c(+) cell population in the non-parenchymal cell population of the mouse liver contains dendritic cells (DC), NK cells, B cells and T cells. In the hepatic CD11c(+) DC population from immunocompetent or immunodeficient [recombinase-activating gene-1 (RAG1)(-/-)] C57BL/6 mice (rigorously depleted of T cells, B cells and NK cells), we identified a B220(+) CD11c(int) subset of 'plasmacytoid' DC, and a B220(-) CD11c(+) DC subset. The latter DC population could be subdivided into a major, immature (CD40(lo) CD80(lo) CD86(lo) MHC class II(lo)) CD11c(int) subset, and a minor, mature (CD40(hi) CD80(hi) CD86(hi) MHC class II(hi)) CD11c(hi) subset. Stimulated B220(+) but not B220(-) DC produced type I interferon. NKT cell activation in vivo increased the number of liver B220(-) DC three- to fourfold within 18 h post-injection, and up-regulated their surface expression of activation marker, while it contracted the B220(+) DC population. Early in virus infection, the hepatic B220(+) DC subset expanded, and both, the B220(+) as well as B220(-) DC populations in the liver matured. In vitro, B220(-) but not B220(+) DC primed CD4(+) or CD8(+)T cells. Expression of distinct marker profiles and functions, and distinct early reaction to activation signals hence identify two distinct B220(+) and B220(-) subsets in CD11c(+) DC populations freshly isolated from the mouse liver.

Breaking tolerance in hepatitis B surface antigen (HBsAg) transgenic mice by vaccination with cross-reactive, natural HBsAg variants

Processing exogenous hepatitis B surface antigen (HBsAg) of the hepatitis B virus (HBV) generates the K(b)-binding S(208-215) epitope 1; processing endogenous HBsAg generates the K(b)-binding S(190-197) epitope 2. Cross-reactive CD8(+) T cell responses were primed to epitope 1 but not epitope 2 when mice were immunized with natural HBsAg(ayw), or HBsAg(adw2) variants differing within both epitopes by one or two residues. Expression of HBsAg(ayw) from a transgene in the liver renders (HBs-tg) mice tolerant to epitope 1 of HBsAg(ayw). CD8(+) T cells specific for epitope 1 could be primed in HBs-tg mice by HBsAg(adw2); these specific CD8(+) T cells cross-reacted with epitope 1 processed from the transgene-encoded HBsAg(ayw). The liver of vaccinated HBsAg(ayw) transgenic mice showed severe histopathology and contained functional (IFNgamma-producing), cross-reactive CD8(+) T cells, and vaccinated HBs-tg mice showed reduced antigenemia. Hence, vaccination with natural HBsAg variants from different HBV sero/genotypes can prime cross-reactive, specific CD8(+) T cell immunity that breaks tolerance to HBsAg.

Early events in the pathogenesis of a murine transfer colitis

Inflammatory bowel disease (IBD) is a chronic, disabling disease. A dysregulated immune response seems to play a pivotal role in the pathogenesis of this disorder. Here we will review current concepts of the adoptive transfer model of IBD with particular emphasis on early events in disease development. In the adoptive transfer model, the reconstitution of immunoincompetent mice with CD4+ T cells from congenic donor animals leads to severe colitis. We will address the question as to which CD4+ T cell subsets might be involved in the induction, suppression, or regulation of disease, and review data concerning the specificity of their T cell receptor and its putative MHC restriction elements. We will also discuss whether and at what anatomical sites donor T cells could be primed in the recipient.

[18F]5-fluoro-2-deoxyuridine-PET for imaging of malignant tumors and for measuring tissue proliferation

The nucleoside 5-fluoro-2-deoxyuridine is a pyrimidine analogue accumulating in proliferative cells. We prospectively evaluated biodistribution of the PET tracer [(18)F]5-fluoro-2-deoxyuridine (FdUrd), its value for imaging malignant tumors, and its correlation to both [(18)F]2-fluoro-2-deoxyglucose (FDG)-PET findings and histological proliferation indices. In 11 previously untreated patients (5 lung carcinoma; 3 soft tissue sarcoma; 2 gastrointestinal carcinoma; 1 non-Hodgkin lymphoma [NHL]), mean doses of 290 MBq FdUrd and 390 MBq FDG were administered intravenously on subsequent days. Static PET scans were initiated 50-70 min after administration and the mean standardized uptake values (SUV) were calculated. Dynamic emission FdUrd scans were performed in 8/11 patients. Time-activity curves of blood and tumors as well as SUV of tumor lesions and organs were calculated. Proliferative activity was evaluated by Ki-67 immunohistostaining of biopsies. Tracer accumulated physiologically in liver, kidney, and bladder. SUVs were: kidney, 4.8 +/- 0.66; liver, 4.1 +/- 0.36; vertebrae, 0.70 +/- 0.17; spleen, 0.37 +/- 0.06; lungs, 0.19 +/- 0.05; femora/humeri, 0.14 +/- 0.03. Five patients exhibited significant intratumoral FdUrd-uptake (2 sarcomas; 1 NHL; 2 lung carcinomas) with mean SUVs ranging from 0.7 to 10.5. Metastases were not detected. Time-activity curves showed a rapid initial increase of intratumoral activity followed by activity retention. FDG-PET was positive in 10/11 patients. Correlation between the SUV of FdUrd-PET and FDG-PET or the tissue proliferation index, respectively, was not significant. FdUrd was a suitable tracer for imaging malignant tumors only in exceptional cases: Sarcoma, NHL, and some lung carcinomas were detected. FdUrd-PET was less effective than FDG-PET. In this group of patients, it was not useful in measuring tissue proliferation.

Epidemiology and virulence gene expression of intracellular group A streptococci in tonsils of recurrently infected adults

Intracellularly persistent group A streptococci (GAS, Streptococcus pyogenes) have been associated with recurrent tonsillopharyngitis and antibiotic treatment failure. As a supplementation of the published in vitro data, conventional bacteriology and molecular epidemiology was performed on material from 29 adult patients of a German army hospital with anamnestic signs of recurrent tonsillopharyngitis. Pre-surgery tonsil swabs and the surgically removed tonsils were examined with respect to growth of aerobic bacteria in absence and presence of antibiotics with exclusively extracellular activity. Under such antibiotic selection, Staphylococcus aureus and GAS were cultured from specimens of 13 and 3 patients, respectively. In every material GAS-positive by culture methods, the intracellular location of the penicillin-susceptible GAS isolates was confirmed by immunohistologic examination of tonsillar sections using a GAS-specific IgG antibody. The three intracellular GAS isolates were typed by emm gene sequencing and could be associated to types M6 and M49 (two isolates). The bacteria were serially passaged on sheep blood agar, and semiquantitative mRNA analysis from virulence genes was performed using bacteria of the 4th and 25th passage after isolation. An M-type-specific pattern of virulence gene expression and different gene expression levels in relation to the passage number were observed.

3'-[18F]fluoro-3'-deoxythymidine ([18F]-FLT) as positron emission tomography tracer for imaging proliferation in a murine B-Cell lymphoma model and in the human disease

Here we describe the evaluation of 3'-[(18)F]fluoro-3'-deoxythymidine [[(18)F]-FLT] as a tracer for positron emission tomography (PET) in a murine model of B-cell lymphoma and in human malignant lymphoma. The human B-cell line DoHH2 expressed high levels of active thymidine kinase 1 (TK-1) as the key enzyme of [(18)F]-FLT metabolism. Immunostaining confirmed high levels of TK-1 in DoHH2 derived xenograft tumors in SCID/SCID mice. In vitro studies demonstrated a time-dependent uptake of [(18)F]-FLT, an efficient phosphorylation to the respective monophosphate and the incorporation of [(18)F]-FLT into the perchloric acid insoluble fraction in DoHH2 cells, indicating the incorporation of this tracer into the DNA. After incubation with [(18)F]FLT for 240 min, 12.5% +/- 1.0% of radioactivity applied to the medium was intracellularly trapped in DoHH2 cells. Specific accumulation of [(18)F]-FLT in the malignant cell clone was confirmed in biodistribution studies in SCID/SCID mice bearing DoHH2-derived tumors. The percentage of injected dose of [(18)F]-FLT per gram of tumor tissue correlated with the tumor-proliferation index as evaluated in BrdUrd-labeling experiments. In a pilot study of 11 patients with both indolent and aggressive lymphoma, [(18)F]-FLT was suitable and comparable to [(18)F]-FDG in the ability to detect malignant lesions by PET scan. Furthermore, we found a close correlation (r = 0.95, P < 0.005) of the [(18)F]-FLT standardized uptake values with the Ki67-labeling index of tissue biopsies (n = 10) in these patients. These results suggest that [(18)F]-FLT represents a novel tracer for PET that enables imaging of proliferation in human lymphoma in vivo.

Colonic lamina propria dendritic cells in mice with CD4+ T cell-induced colitis

CD11c(+) (F4/80(-) CD68(-)) dendritic cells (DC) in the colonic lamina propria (cLP) of normal and immunodeficient (RAG1(-/-)) C57BL/6 (B6) mice show high surface expression of MHC class I/II molecules and CD1d, and low surface expression of CD40, CD80, CD86 costimulator molecules. CD4(+) alpha beta T cells from normal or MHC class II-deficient B6 mice transferred into congenic RAG1(-/-) hosts induce a progressive, lethal colitis. Concomitant with colitis development, DC in the inflamed cLP increase in number and up-regulate surface expression of CD1d, MHC class II molecules and CD40, CD80, CD86 costimulator molecules. cLP DC from non-transplanted (healthy) and transplanted (diseased) mice produce similar amounts of IL-12 p70 and IL-10 in response to CD40 signaling, but the inducible IL-12 p40 release is 5-15-fold higher in mice with colitis than in non-transplanted mice. Binding of IL-12 p40 to p19 generates IL-23. Freshly isolated cLP lymphocytes (cLPL) from transplanted, diseased mice express 3-10-fold more p19 transcripts than cLPL from non-transplanted, healthy mice. p19 expression by cLPL is further up-regulated in response to CD40 ligation. Freshly isolated cLP DC from transplanted mice with colitis (but not from non-transplanted controls) stimulate IFN-gamma (but not IL-4 or IL-13) release by co-cultured NKT cells. Incolitis, DC accumulate in the cLP, show an activated surface phenotype, up-regulate IL-12 p40 and p19 expression, and 'spontaneously' stimulate NKT-like cells. cLP DC may be interesting targets for novel therapeutic approaches to modulate mucosal T cell responses in situ.

The hepatic immune system

The liver regulates T-cell homeostasis, induces T-cell tolerance, and supports intrahepatic T-cell responses against hepatotropic pathogens. Many data from clinical and preclinical systems provide supportive evidence for these diverse roles of the liver in modulating peripheral (systemic, mucosal, and intrahepatic) T-cell immunity. Little information is available on the cellular and molecular mechanisms that mediate the dual role of the liver in tolerizing T-cell responses and in supporting intrahepatic priming of T-cell responses. Understanding these immunoregulatory effects in the liver may offer insight into clinically relevant immunopathologies of this organ.

Activating immunity in the liver. II. IFN-beta attenuates NK cell-dependent liver injury triggered by liver NKT cell activation

Dendritic cell (DC)-dependent activation of liver NKT cells triggered by a single i.v. injection of a low dose (10-100 ng/mouse) of alpha-galactosyl ceramide (alphaGalCer) into mice induces liver injury. This response is particularly evident in HBs-tg B6 mice that express a transgene-encoded hepatitis B surface Ag in the liver. Liver injury following alphaGalCer injection is suppressed in mice depleted of NK cells, indicating that NK cells play a role in NK T cell-initiated liver injury. In vitro, liver NKT cells provide a CD80/86-dependent signal to alphaGalCer-pulsed liver DC to release IL-12 p70 that stimulates the IFN-gamma response of NKT and NK cells. Adoptive transfer of NKT cell-activated liver DC into the liver of nontreated, normal (immunocompetent), or immunodeficient (RAG(-/-) or HBs-tg/RAG(-/-)) hosts via the portal vein elicited IFN-gamma responses of liver NK cells in situ. IFN-beta down-regulates the pathogenic IL-12/IFN-gamma cytokine cascade triggered by NKT cell/DC/NK cell interactions in the liver. Pretreating liver DC in vitro with IFN-beta suppressed their IL-12 (but not IL-10) release in response to CD40 ligation or specific (alphaGalCer-dependent) interaction with liver NKT cells and down-regulated the IFN-gamma response of the specifically activated liver NKT cells. In vivo, IFN-beta attenuated the NKT cell-triggered induction of liver immunopathology. This study identifies interacting subsets of the hepatic innate immune system (and cytokines that up- and down-regulate these interactions) activated early in immune-mediated liver pathology.