RIG-I-like helicases induce immunogenic cell death of pancreatic cancer cells and sensitize tumors toward killing by CD8(+) T cells.

Pancreatic cancer is characterized by a microenvironment suppressing immune responses. RIG-I-like helicases (RLH) are immunoreceptors for viral RNA that induce an antiviral response program via the production of type I interferons (IFN) and apoptosis in susceptible cells. We recently identified RLH as therapeutic targets of pancreatic cancer for counteracting immunosuppressive mechanisms and apoptosis induction. Here, we investigated immunogenic consequences of RLH-induced tumor cell death. Treatment of murine pancreatic cancer cell lines with RLH ligands induced production of type I IFN and proinflammatory cytokines. In addition, tumor cells died via intrinsic apoptosis and displayed features of immunogenic cell death, such as release of HMGB1 and translocation of calreticulin to the outer cell membrane. RLH-activated tumor cells led to activation of dendritic cells (DCs), which was mediated by tumor-derived type I IFN, whereas TLR, RAGE or inflammasome signaling was dispensable. Importantly, CD8α(+) DCs effectively engulfed apoptotic tumor material and cross-presented tumor-associated antigen to naive CD8(+) T cells. In comparison, tumor cell death mediated by oxaliplatin, staurosporine or mechanical disruption failed to induce DC activation and antigen presentation. Tumor cells treated with sublethal doses of RLH ligands upregulated Fas and MHC-I expression and were effectively sensitized towards Fas-mediated apoptosis and cytotoxic T lymphocyte (CTL)-mediated lysis. Vaccination of mice with RLH-activated tumor cells induced protective antitumor immunity in vivo. In addition, MDA5-based immunotherapy led to effective tumor control of established pancreatic tumors. In summary, RLH ligands induce a highly immunogenic form of tumor cell death linking innate and adaptive immunity.

Individual and common antigen-recognition sites of liver-derived T cells in patients with autoimmune hepatitis.

Autoimmune hepatitis (AIH) is characterized by dense T-cell infiltrations in the liver tissue, but little is known how T cells influence the pathogenesis. To address this question, the distribution of T-cell receptor variable beta-chain (TCR Vbeta) transcripts of peripheral blood and liver-infiltrating T cells from previously untreated patients with newly diagnosed acute exacerbated AIH was investigated. Furthermore, the lengths and sequences of complementary-determining region 3 (CDR3) were studied. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and CDR3 spectratyping revealed multiple clonal expansions of liver-infiltrating T cells but not peripheral T cells within various TCR Vbeta families. Further analysis of overexpressed TCR Vbeta transcripts using TCR beta-chain-joining element (TCR Jbeta)-specific primers in a nested PCR showed characteristic Vbeta/Jbeta combinations. Subsequent sequencing of CDR3 regions from PCR products confirmed the clonality of T-cell expansions and the usage of common and individual CDR3 motifs. In conclusion, the clonality of expanded T cells within the liver tissue during early clinical manifestation of untreated AIH indicated that autoantigen-specific T cells accumulate at the inflammation site. Individual and common CDR3 motifs argued for predominant epitopes that were recognized by liver-infiltrating T cells in AIH patients.

Durability of HBeAg seroconversion following antiviral therapy for chronic hepatitis B: relation to type of therapy and pretreatment serum hepatitis B virus DNA and alanine aminotransferase.

BACKGROUND AND AIMS: Interferon (IFN) induced hepatitis B e antigen (HBeAg) seroconversion is durable in 80-90% of chronic hepatitis B patients. Preliminary reports on the durability of HBeAg seroconversion following lamivudine are contradictory. We investigated the durability of response following IFN, lamivudine, or IFN-lamivudine combination therapy in a meta-analysis of individual patient data. PATIENTS AND METHODS: Twenty four centres included 130 patients in total with an HBeAg seroconversion (HBeAg negative, antibodies to hepatitis B e antigen positive) at the end of antiviral therapy: 59 with lamivudine, 49 with interferon, and 22 with combination therapy. Relapse was defined as confirmed reappearance of HBeAg. RESULTS: The three year cumulative HBeAg relapse rate by the Kaplan-Meier method was 54% for lamivudine, 32% for IFN, and 23% for combination therapy (p=0.01). Cox regression analysis identified pretreatment hepatitis B virus (HBV) DNA, alanine aminotransferase (ALT), sex, and therapy as independent predictive factors of post-treatment relapse; Asian race, previous therapy, centre, and type of study were not predictive of relapse. The relative HBeAg relapse risk of lamivudine compared with IFN therapy was 4.6 and that of combination therapy to IFN therapy 0.7 (p(overall)=0.01). CONCLUSIONS: The durability of HBeAg seroconversion following lamivudine treatment was significantly lower than that following IFN or IFN-lamivudine combination therapy. The risk of relapse after HBeAg seroconversion was also related to pretreatment levels of serum ALT and HBV DNA, but independent of Asian race.

Reduced virus specific T helper cell induction by autologous dendritic cells in patients with chronic hepatitis B - restoration by exogenous interleukin-12.

Insufficient stimulatory capacities of autologous dendritic cells (DC) may contribute in part to impaired T cell stimulation and therefore viral persistence in patients with chronic hepatitis B virus (HBV) infection. In order to characterize the antigen presenting functions of DC from chronic HBV carriers and controls antigen specific T cell responses were analysed. CD34+ peripheral blood progenitor cells were differentiated to immature DC in the presence of GM-CSF, IL-6/IL-6R fusion protein and stem cell factor. Proliferative CD4+ T cell responses and specific cytokine release were analysed in co-cultures of DC pulsed with HBV surface and core antigens or tetanus toxoid and autologous CD4+ T cells. Cultured under identical conditions DC from chronic HBV carriers, individuals with acute resolved hepatitis B and healthy controls expressed similar phenotypical markers but chronic HBV carriers showed less frequent and weaker HBV antigen specific proliferative T helper cell responses and secreted less interferon-gamma while responses to the tetanus toxoid control antigen was not affected. Preincubation with recombinant IL-12 enhanced the HBV specific immune reactivities in chronic HBV patients and controls. In conclusion, the weak antiviral immune responses observed in chronic hepatitis B may result in part from insufficient T cell stimulating capacities of DC. Immunostimulation by IL-12 restored the HBV antigen specific T cell responses and could have some therapeutical benefit to overcome viral persistence.

[Autoimmune hepatitis and overlap syndrome: therapy]. / Autoimmunhepatitis und Overlap-Syndrom: Therapie.

Autoimmune Hepatitis (AIH), primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) represent acute and chronic inflammatory liver diseases in which immune reactions against host antigens are found to be the major pathological mechanism. Only for AIH there is evidence of an autoimmune etiology and humoral and cellular immune reactions are found directed against various liver cell antigens. By diverse autoantibodies several subgroups of autoimmune hepatitis can be distinguished. A very important disease promoting factor seems to be the genetically determined background for autoimmunity characterized by the HLA haplotype A1, B8 and DR3, respectively DR4. Although the histopathology of AIH shows no pathognomonic features distinguishing this type of hepatitis from virus induced chronic hepatitis there are some distinct characteristic morphological lesions. If untreated the prognosis of AIH is unfavourable but the benefit from immunosuppressive therapy with prednisolone and azathioprin is well established. In the last years there was increasing evidence for an overlap syndrome between AIH and PBC and rarely AIH and PSC. These patients are characterized by PBC characteristic bileduct lesions and oftenly antimitochondrial antibodies (AMA). They also show AIH typical inflammatory hepatic lesions in the periportal areas and portal tracts and oftenly the typical genetical background, the HLA haplotype A1, B8, DR3 or DR4. Most of these patients respond probably to a combination therapy containing prednisolon, azathioprine and ursodesoxycholic acid that leads to the reduction of the inflammatory activity.

Induction of strong hepatitis B virus (HBV) specific T helper cell and cytotoxic T lymphocyte responses by therapeutic vaccination in the trimera mouse model of chronic HBV infection.

Humanized BALB/c mice (termed trimera mice) conditioned by lethal total body irradiation and bone marrow transplantation from SCID mice have been described to support rapid engraftment of human peripheral blood mononuclear cells (PBMC) and the induction of strong B and T cell responses after immunization in vivo. Moreover, these mice can be infected with the hepatitis B and C viruses (HBV, HCV). The current study employed this model to study therapeutic vaccination approaches against the HBV. Thus, strong primary Th cell responses against the HBV core (HBc) and the Borrelia burgdorferi control antigen were induced by transfer of antigen-loaded dendritic cells together with autologous PBMC from HBV-naive donors as well as by vaccination with high doses of antigen or a DNA plasmid encoding for HBcAg. Moreover, primary peptide-specific CTL responses against the immunodominant epitope HBc(18 - 27) were induced by HBc particle or DNA vaccination of chimera engrafted with HBV-naive PBMC. Finally, strong HBc-specific Th cell and antibody responses were induced by HBc or DNA vaccination of mice reconstituted with PBMC from a chronic HBV patient. Thus, since HBc represents the immunodominant antigen in self-limited HBV infection, HBc particles or DNA vectors are good candidates for therapeutic vaccination, that will be further studied in our model and clinical studies.

Quantitative analysis of specific Th1/Th2 helper cell responses and IgG subtype antibodies in interferon-alpha-treated patients with chronic hepatitis C.

This study aimed to characterise the immune mechanisms relevant to viral clearance in interferon (IFN)-alpha-treated chronic hepatitis C virus (HCV) infection. Proliferative responses of peripheral blood mononuclear cells from sustained complete IFN-alpha therapy responders (n = 8), nonresponders (n = 13), untreated patients (n = 10), and healthy controls (n = 5) were measured retrospectively upon stimulation with recombinant HCV-antigens (core, helicase, NS3, NS4, and NS5) and the secretion of IFN-gamma and interleukins (IL-4, IL-5, IL-10, and IL-12) were tested by ELISA. Furthermore, IFN-gamma as well as IL-10 secreting CD4+ T cells were quantitated by intracellular cytokine staining. Anti-HCV core and NS3-specific IgG subclass antibodies were quantitated in the corresponding patient sera. Sustained therapy responders had more frequent and stronger NS3 and helicase-specific cellular immune responses than nonresponders, untreated HCV patients and healthy controls. Independent from therapy outcome HCV-stimulated T cells in IFN-alpha treated patients secreted preferentially IFN-gamma The Th2 cytokines IL-4 and IL-10 were even decreased in nonresponders, while the IL-12 secretion was not influenced. With respect to the humoral immune response sustained complete responders showed significantly reduced IFN-gamma independent anti-HCV-core and -NS3 IgG1 antibody synthesis. In conclusion, vigorous NS3-specific T-helper cell responses were associated with viral clearance in IFN-alpha recipients; however, the cytokine and antibody analysis argues against a Th1/Th2 imbalance as a major factor that influence the therapy outcome.

Long-term management and prognosis of autoimmune hepatitis (AIH): a single center experience.

BACKGROUND: Controlled trials have firmly established the need for immunosuppressive therapy in autoimmune hepatitis. However, reports about long-term management and prognosis of the disease are scarce. PATIENTS AND METHODS: We reviewed the charts of 103 consecutive patients with a well-documented long-term course of autoimmune hepatitis who had been carefully managed over a mean observation period of 95 months (12-405 months). RESULTS: Under immunosuppressive therapy 94 patients (91.2%) reached complete remission after a mean treatment duration of 3 +/- 3 months. 28 of the 103 patients (27.2%) were eligible for a trial of treatment withdrawal after a mean treatment duration of 32.2 months (range: 12-81 months). 21 of these patients (75%) had a relapse following treatment withdrawal. 13.6% of patients had intolerance of or severe side effects to azathioprine. There was no increase in tumor risk during a cumulative observation period of 423 patient-years of azathioprine therapy. Corticosteroid side effects occurred mostly during induction therapy, but were usually minor and resolved upon dose reduction. During a cumulative observation period of 842 patient-years no liver related deaths occurred and no patient had to be referred to liver transplantation, even though 30 patients (29.1%) had histological evidence of cirrhosis at presentation. The overall 5- and 10-year survival of patients with autoimmune hepatitis was identical to an age- and sex-matched control population. CONCLUSION: Our study shows that the majority of patients with AIH do achieve a complete remission within 3 months, but require long-term or permanent immunosuppressive therapy that is usually well tolerated. Long-term survival in well-managed patients is excellent.

[Lymphoma-simulating presentation of focal nodular hyperplasia (FNH) of the liver]. / Eine lymphomähnliche Präsentation einer fokalen nodulären Hyperplasie (FNH) der Leber.

UNLABELLED: A 51-year-old woman, who had taken oral contraceptive drugs for 11 years, was referred to our Unit for examination of an asymptomatic 3.6 x 4.1 cm hypoechoic liver mass found by ultrasound examination carried out in the course of gynecological screening. INVESTIGATIONS: Laboratory evaluation revealed mild elevated liver enzymes. Computed tomography exhibited a hypervascularized lesion in segment 4 of the liver resembling a hemangioma or focal nodular hyperplasia but FNH was favored since magnetic resonance imaging showed a central scar within the hepatic lesion. Hepatobiliary scintigraphy was not typical thus an ultrasound-guided needle biopsy was performed. Histological examination revealed lymphoma-like infiltrates close to normal liver cells. However, the molecular biological examination showed oligoclonality of the infiltrating T-cells. Blood examinations, bone-marrow punctuation and CT thorax scan did not show any other lymphoma-like lesion. TREATMENT AND COURSE: After 5, 10 and 15 months the untreated patient was re-examined by MRI. The focal lesion showed an unchanged size and again a FNH-typical imaging. Liver-specific contrast enhancement was not suggestive for lymphoma. The lymphocytes were interpreted as an atypical lymphoid inflammatory infiltrate of a non-neoplastic lesion of the liver. CONCLUSIONS: The focal nodular hyperplasia can be a very difficult diagnosis in imaging and histopathological examinations. The lymphoma of the liver can be a rare but possible differential diagnosis.

[Retrospective cohort study of lamivudine therapy in patients with chronic hepatitis B]. / Retrospektive Kohortenstudie zur Lamivudintherapie bei Patienten mit chronischer Hepatitis B.

BACKGROUND AND AIMS: Lamivudine, a nucleoside analogue with specific antiviral activity against the hepatitis B virus, is now available as an alternative therapeutic option to standard interferon-alpha treatment in chronic hepatitis B. Larger studies with lamivudine treatment in chronic hepatitis B were mainly performed in North America and Asia. Data on treatment responses in European patients are sparse. Therefore, we evaluated the efficacy and safety of lamivudine therapy in Central European patients and compared the data with the results from international trials. PATIENTS AND METHODS: In this retrospective, multicenter, cohort study, 95 patients with chronic hepatitis B (median age: 40.4 years, male: 87 patients, female: 8 patients, HBeAg positive: 47 patients, anti-HBe positive: 48 patients), who were treated with lamivudine (100-300 mg/d per os) between 1997 to 1999, were enrolled. RESULTS: During lamivudine treatment a virologic response with HBeAg to anti-HBe seroconversion was achieved in 22/47 (47%) of the HBeAg positive patients. Pretreatment ALT levels (> threefold the upper limit of normal; p = 0.03) and HBV-DNA serum concentration (< or = 100 pg/ml; p = 0.08) were identified as positive predictors for virologic responses. The virologic response was sustained in six of nine patients who had a follow-up period (median 26 weeks). In anti-HBe positive patients a virologic response with undectable HBV-DNA levels was achieved in 35/48 (73%) patients during lamivudine treatment. Side effects during lamivudine therapy were generally mild and reversible. CONCLUSIONS: In this retrospective cohort study virologic end-of-treatment responses to lamivudine monotherapy in patients with chronic hepatitis B were comparable with yet reported international trials. Thus, lamivudine represents a cost-effective and well tolerable option in addition to IFN-alpha in the treatment of chronic hepatitis B.

T cell receptor Vbeta chain restriction and preferred CDR3 motifs of liver-kidney microsomal antigen (LKM-1)-reactive T cells from autoimmune hepatitis patients.

AIMS/BACKGROUND: The liver-kidney-microsomal antigen (LKM-1) has been recognized as a major CD4+ T cell antigen in autoimmune hepatitis (AIH). The aim of this study was to characterize the antigen recognition sites of the variable T cell receptor beta-chain (TCRBV) of T cells specific to LKM-1. METHODS: By repeated stimulation of T cells with a recombinant LKM-1 antigen or an LKM-derived peptide followed by limited dilution, we generated T cell clones. Usage of TCRBV was analyzed by RT-PCR and CDR3 antigen recognition sites were sequenced. RESULTS: The 18 LKM-1 specific T cell clones isolated from six AIH patients preferentially expressed the TCR elements BV9, BV5S2+S3, BV6, and BV13S1. Four BV9+ T cell clones rearranged the joining element JB1S3 within their CDR3 regions. JB2S3 was detected in another four clones together with BV5S2+S3 or BV13S1. A conserved sequence motif, Q(N)G(X)N, was seen in the diversity regions of five clones (36%). In order to identify T cells expressing the preferred TCRBV molecules in situ, immunohistologic examination of liver biopsies was performed. In AIH patients an accumulation of T cells expressing TCRBV 13S1, BV8 and BV5S3 was observed. CONCLUSIONS: Our data define TCRBV restriction and preferred CDR3 features of LKM-1 specific T cells. The in situ localization of T cells expressing these restricted TCR molecules may suggest a pathogenic relevance of LKM-1 specific cellular immune responses.

The gp130-stimulating designer cytokine hyper-IL-6 promotes the expansion of human hematopoietic progenitor cells capable to differentiate into functional dendritic cells.

OBJECTIVE: Hyper-IL-6, a fusion protein of interleukin-6 and its specific receptor, together with stem cell factor leads to the proliferation of primitive hematopoietic progenitor cells. Based on these findings, the current study examined whether hyper-IL-6 promotes the growth of precursor cells that can be further differentiated into dendritic cells in the presence of additional cytokines. METHODS: Dendritic cell cultures were generated from CD34(+) hematopoietic progenitor cells derived either from bone marrow or from peripheral blood. CD34(+) cells were cultured in the presence of cytokines for 2 weeks and then used for phenotyping and T-cell stimulation assays. RESULTS: Hyper-IL-6 in the presence of stem cell factor induced a 60- to 80-fold expansion of CD34(+) progenitor cells following 2 weeks of culture in serum-free medium. The addition of granulocyte-macrophage colony-stimulating factor to hyper-IL-6 and stem cell factor was essential for the differentiation of expanded progenitor cells into antigen presenting cells capable of inducing a primary T-cell response to soluble protein, which is a typical feature of dendritic cells. Phenotypic analyses confirmed the expansion of immature dendritic cells, which could be further differentiated into mature CD83(+) dendritic cells under the influence of interleukin-4, interleukin-1beta, tumor necrosis factor-alpha, and prostaglandin E(2). The capacity of expanded dendritic cells to stimulate protein-specific CD4(+) T cells was used to stimulate a primary T-helper cell response to the recombinant protein of the hepatitis-B core antigen in healthy donors. CONCLUSION: The expansion and differentiation of functional dendritic cells from CD34(+) progenitor cells under serum-free culture conditions allow for the possibility to develop more effective ways to immunize against viral infections and tumor diseases.

Reduced hepatitis B virus surface antigen-specific Th1 helper cell frequency of chronic HBV carriers is associated with a failure to produce antigen-specific antibodies in the trimera mouse.

In chronic hepatitis B virus (HBV) infection weak antiviral immune responses are associated with viral persistence. We studied possible immune deficits underlying the lack of serum antibodies of such patients against the HBV surface antigen (HBsAg) in a novel human/mouse chimeric model. A hepatitis B surface antigen (HBs) vaccination of Balb/c mice engrafted with peripheral blood mononuclear cells (PBMC) of naturally HBV-immunized donors induced high frequencies of human HBsAg-specific B and T helper 1 (Th1) cells. These responses were associated with high serum anti-HBs antibody levels of the subclasses immunoglobulin G1 (IgG1) and IgG2 that are driven by interleukin-2 (IL-2) and interferon-gamma (IFN-gamma). In contrast, PBMC of chronic HBV carriers transplanted into the chimera failed to produce anti-HBs antibodies after vaccination with HBsAg and exhibited a deficit of antigen-specific Th1 cells. A possible influence of HBsAg or viremia was excluded by the lack of viral replication in such chimera. The observed T-cell defect was specific for HBsAg, as the B- and T-cell responses to tetanus toxoid (TT) were fully retained. Thus, our study shows that viral persistence in chronic HBV carriers is associated with an HBsAg-specific Th1 cell defect, which likely is responsible for the insufficient neutralizing anti-HBs-antibody response and is not reversed by HBs vaccination. Alternative approaches to induce HBs-specific Th1 cell responses might represent a future therapeutic option.

Cellular and humoral immune responses induced by intradermal or intramuscular vaccination with the major hepatitis B surface antigen.

The vaccination route may influence the success of immunization against pathogens. The conventional intramuscular (i.m.) application of a vaccine containing the hepatitis B virus (HBV) surface antigen (HBsAg) led to protective anti-HBs antibody levels in the majority of vaccine recipients. In this study, we vaccinated healthy volunteers and a group of i.m. vaccine nonresponders via the intradermal (i.d.) route and analyzed the HBV-specific B-cell response as well as class-II- and class-I-restricted T-cell responses by (3)H-thymidine uptake, enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immunospot assay (ELISPOT). The results were then compared with i.m. vaccinated controls. I.d. vaccinations were well tolerated and induced neutralizing anti-HBs antibodies in all naive vaccine recipients and, importantly, all but one former i.m. nonresponder developed protective anti-HBs serum antibody levels after 2 or 3 i.d. immunizations. On the cellular level, i.d. vaccine recipients showed significantly higher anti-HBs producing B-cell frequencies and more vigorous class-II-restricted T-helper (Th) cell responses than i.m. controls. However, although the HBsAg-specific T cells were characterized by their cytokine release as Th1-like cells in both groups, human leukocyte antigen (HLA)-A2+ individuals who received the soluble HBsAg via the i.d. route developed higher peptide-specific cytotoxic CD8+ T cell precursor (CTLp) frequencies. In conclusion, i.d. HBsAg vaccination is more effective even in former i.m. vaccine nonresponders with respect to antibody induction and specific B- and T-cell responses. The induction of virus-specific CTLp may provide the rationale to study the i.d. HBsAg vaccine in the treatment of chronic hepatitis B.

[Synthesis of tumor affinity label Yb-169- and Y-90- porphyrin complexes and animal experimental investigations with various Yb-169-porphyrins]. / Synthese tumoraffiner Yb-169- und Y-90-Porphyrin-Komplexe und tierexperimentelle Untersuchung verschiedener Yb-169-Porphyrine.

AIM: It should be shown, that it is possible to insert radioactive isotopes of Yb and Y into some selected porphyrins. Besides, first informations about the biodistribution of Yb-169-por-phyrin-complexes should be obtained. METHODS: Carrier added radioactive isotopes were used for the synthesis of the metal porphyrin complexes. The animal experiments were done with mamma carcinoma bearing mice. The activity of the organs was determined 5 and 24 h after i.v. injection in a well counter. RESULTS: Four Yb-169-porphyrin complexes and Y-90-porphyrin complexes could be synthesized in non-carrier-free form. This was verified by absorption spectra, TLC and HPLC. Depending on the complex, the average tumour/background ratios were between 2 and 20. CONCLUSION: The synthesized radioactive metal-porphyrin complexes showed a clear tumour-affinity which could be used for tumour scintigraphy or perhaps therapy if the synthesis is improved (goal: reduction of carrier, other radionuclides).