Published papers

To identify tumor antigens for glioma, a human testis cDNA library was screened by serological identification of antigens by recombinant expression cloning with sera from glioma patients. In this screening, the most frequently isolated antigen was SOX6, an Sry-related high-mobility group (HMG) box-containing gene. SOX6 is a transcriptional factor that is specifically expressed in the developing central nervous system and in the early stages of chondrogenesis in mouse embryos. IgG antibodies against SOX6 were detected in sera from 12 of 36 glioma patients (33.3%), 0 of 14 patients with other brain disease (0%), and one of 54 other cancer patients (1.9%). In sera from 37 healthy individuals, no IgG responses against SOX6 were detected, except in an elderly female. Furthermore, Western blot and ELISA analyses with sera from glioma patients revealed that the DNA-binding domain, the HMG box of SOX6, might be a dominant epitope of IgGs against SOX6. RT-PCR and Northern blot analysis revealed that the SOX6 gene was more highly expressed in glioma tissues than in normal adult tissues, except testis. Western blot analysis with an anti-SOX6 antibody demonstrated that the SOX6 protein was expressed in glioma tissues, but not in normal adult brain tissue. Immunohistochemical analysis with the anti-SOX6 antibody showed that all the glioma tissues analysed expressed SOX6 in tumor cells, but only a few SOX6-positive cells were detected in non-neoplastic tissues from the cerebral cortex. In summary, these results indicate that the developmentally regulated transcription factor SOX6 is aberrantly expressed in glioma and specifically recognized by IgGs from glioma patients' sera.

Nearly all autoantibody specificities in sera from patients with systemic sclerosis (SSc) target proteins distributed ubiquitously, and Abs against proteins whose expression is restricted to the affected sites have not been identified. In this study we describe SSc-specific autoantibody to a novel testicular Ag, termed protein highly expressed in testis (PHET), which is ectopically over-expressed in SSc dermal fibroblasts. A partial cDNA encoding PHET was isolated by immunoscreening of a HepG2 cDNA library with an SSc serum. PHET appeared to be a member of the UniGene cluster Hs.129872, but had a unique exon composition and a characteristic mRNA expression profile restricted to the testis. Serum Abs to a recombinant PHET fragment were detected in nine (8.4%) of 107 SSc patients, but in none of 50 systemic lupus erythematosus patients or 77 healthy controls. In SSc patients, the presence of anti-PHET Abs was associated with diffuse cutaneous SSc and lung involvement (p = 0.02 and 0.01, respectively). PCR-based quantitative analysis of PHET mRNA expression in cultured dermal fibroblasts showed increased expression of PHET mRNA in SSc fibroblasts compared with control fibroblasts. PHET-reactive Abs purified from SSc sera stained the cytoplasm of SSc dermal fibroblasts, and the staining intensity tended to be more prominent on SSc compared with control fibroblasts. These findings suggest that the autoantibody response to PHET can be induced by ectopic overexpression of PHET in dermal fibroblasts in SSc patients.

Objective. To examine HLA class II gene associations with anti-RNA polymerase (RNAP) I/III antibody responses in patients with systemic sclerosis (SSc). Methods. HLA-DRB1, DRB3, DRB4, and DQB1 alleles were determined using polymerase chain reaction-based methods in 257 SSc patients (129 Japanese and 128 Caucasians) and 271 race-matched regional controls (138 Japanese and 133 Caucasians). Anti-RNAP I/III antibodies were identified by immunoprecipitation assay, and reactivities to individual RNAP subunits were determined by immunoblots using affinity-purified RNAP I, II, and III. Results. Serum anti-RNAP I/III antibody was detected in 10 (8%) Japanese and 24 (19%) Caucasian patients with SSc. The presence of anti-RNAP I/III antibodies was associated with DRB1*0405, DRB4*01, and DQB1*0401 in Japanese, and with DRB3*02 in Caucasians, but these associations were weak and inconsistent between these 2 ethnic groups. When anti-RNAP I/III-positive SSc patients were divided into 2 groups based on the presence or absence of reactivities to individual RNAP subunit proteins, significant associations of anti-IIa/IIo reactivity with DRB3*02, anti-Ia reactivity with DRB1*04, anti-43-kDa subunit reactivity with DRB4*01, and anti-34-kDa subunit reactivity with DRB1*15 were detected. These HLA associations with subunit reactivities were generally shared by Japanese and Caucasian patients with SSc. Conclusion. Our results suggest that in patients with SSc, anti-RNAP I/III antibodies are composed of subsets defined by combinations of reactivities to individual RNAP subunits having specific HLA class II correlations.

Circulating CD14+ monocytes are precursors of phagocytes, such as macrophages and dendritic cells. Here we report primitive cells with a fibroblast-like morphology derived from human peripheral blood CD14+ monocytes that can differentiate into several distinct mesenchymal cell lineages. We named this cell population monocyte-derived mesenchymal progenitor (MOMP). MOMPs were obtained in vitro from human peripheral blood mononuclear cells cultured on fibronectin in the presence of fetal bovine serum alone as a source of growth factors. MOMPs had a unique molecular phenotype-CD14 +CD45+CD34+type I collagen+-and showed mixed morphologic and molecular features of monocytes and endothelial and mesenchymal cells. MOMPs were found to be derived from a subset of circulating CD14+ monocytes, and their differentiation required that they bind fibronectin and be exposed to one or more soluble factors derived from peripheral blood CD14- cells. MOMPs could be expanded in culture without losing their original phenotype for up to five passages. The induction of MOMPs to differentiate along multiple limb-bud mesodermal lineages resulted in the expression of genes and proteins specific for osteoblasts, skeletal myoblasts, chondrocytes, and adipocytes. Our findings represent the first evidence that human circulating CD14+ monocytes are a source of progenitors that exhibit mesenchymal cell differentiation.

We conducted a pilot study to assess the feasibility and efficacy of immunotherapy for stage IV malignant melanoma patients resistant to conventional therapies involving vaccination with mature dendritic cells (mDCs) combined with administration of low dose interleukin-2, Autologous monocytes were harvested from a single apheresis and cultured for 7 days with granulocyte-macrophage colony-stimulating factor and interleukin-4, yielding immature dendritic cells (iDCs), which were then cryopreserved until use. For 4 days prior to vaccination, iDCs were exposed to autologous tumour lysate combined with tumour necrosis factor-α to induce terminal differentiation into mDCs. Patients were then vaccinated weekly with 107 mDCs for 10 weeks and given 350-700 kIU of interleukin-2 three times per week. Of the 10 patients in the study, one showed stable disease, seven showed progressive disease, and two showed mixed responses, including partial tumour regression, and were therefore given 20 additional injections. Only minimal adverse events were noted, including localized skin reactions and mild fever (NIH-CTC grade 0-1). Median survival from the first vaccination was 240 days (range 31-735 days). In vitro, melanoma patient-derived dendritic cells (DCs) showed reduced cell surface expression of CD1a antigen on iDCs and reduced CD86 and HLA-DR expression on mDCs. In addition, antigen uptake, chemotaxis and antigen presentation were all attenuated in DCs from the patients. In summary, although improvement of clinical efficacy will require further research, autologous tumour lysate-pulsed monocytederived mDCs could be safely harvested, cryopreserved and administrated to patients without obvious complications.

Colorectal cancers with microsatellite instability (MSI+ CRCs) caused by dysfunction of DNA mismatch repair have unique clinicopathological characteristics including good prognosis with T-cell infiltration in tumor. To identify tumor antigens that induce immune response against MSI+ CRC, SEREX (serological analysis of recombinant cDNA expression cloning) was applied. By screening a λ phage cDNA library constructed from three MSI+ CRC cell lines with serum from a patient with MSI+ CRC with abundant T-cell infiltrates in tumor, 64 antigens were isolated. Immunogenicity of each antigen was evaluated by screening sera from patients with various cancers and from healthy individuals, and specific IgG antibodies (Abs) for 49 antigens were detected only in MSI+ CRC patients. A frameshift mutation in the repetitive G sequences (microsatellite) in the coding region of CDX2, one of the identified antigens, was found in the tumor tissue of the patient who had anti-CDX2 serum Ab. The Ab recognized both the COOH-terminal tumor-specific peptides created by the frameshift mutation and the NH2-terminal normal peptides of CDX2 when Western blot analysis was performed using various bacterial recombinant CDX2 proteins including the normal and altered peptides, which indicated that immune response could be raised against tumor-specific peptides generated through MSI. The anti-CDX2 Ab was detected only in the patient with the CDX2 frameshift mutation in tumor and disappeared 7 years after the curative resection, suggesting that this immune response may also be useful as a tumor marker. No altered subcellular localization and transcription ability was demonstrated in the mutated CDX2, although decreased expression was suggested in immunohistochemical analysis. Therefore, tumor-specific peptides generated by MSI may be involved in antitumor immune responses and may be useful for the development of diagnostic and therapeutic methods for patients with MSI+ CRC.

Identification of human tumor antigens led to development of new immunotherapies for patients with cancer. Identification of T-cell epitopes allowed us to monitor antitumor T-cell responses quantitatively and qualitatively during immunotherapy as well as to develop more efficient immunotherapies with sufficient amounts of antigens in more immunogenic forms. Various immunotherapies, passive immunotherapies, including adoptive transfer of tumor reactive T-cells or allogeneic antigen-specific donor T-cells, and active immunization with identified tumor antigens or dendritic cells pulsed with tumor antigens are being evaluated in clinical trials. Although tumor regression has been observed in some patients, further improvement is required.

Thrombocytopenia is a common manifestation in patients with liver cirrhosis (LC), but its underlying mechanism remains controversial. This study examined the role of anti-platelet autoimmunity in cirrhotic thrombocytopenia by determining the autoantibody response to GPIIb-IIIa, a major platelet surface autoantigen recognized by anti-platelet antibodies in patients with idiopathic thrombocytopenic purpura (ITP). Circulating B cells producing anti-GPIIb-IIIa antibodies as well as platelet-associated and plasma anti-GPIIb-IIIa antibodies were examined in 72 patients with LC, 62 patients with ITP, and 52 healthy controls. In vitro anti-GPIIb-IIIa antibody production was induced in cultures of peripheral blood mononuclear cells (PBMCs) by stimulation with GPIIb-IIIa. The frequency of anti-GPIIb-IIIa antibody-producing B cells in patients with LC was significantly greater than in healthy controls (10.9 ± 6.2 vs. 0.4 ± 0.3/105 PBMCs; P < .0001) and was even higher than the frequency in patients with ITP (8.2 ± 5.2; P = .007). Anti-GPIIb-IIIa antibodies in the patients with LC and ITP were mainly present on the surfaces of circulating platelets rather than in the plasma in an unbound form. Furthermore, PBMCs from patients with LC and ITP produced anti-GPIIb-IIIa antibodies on antigenic stimulation with GPIIb-IIIa in vitro, and the specific antibodies produced had the capacity to bind normal platelet surfaces. In conclusion, the similar profile of the anti-GPIIb-IIIa autoantibody response in patients with LC and ITP suggests that autoantibody-mediated platelet destruction may contribute at least in part to cirrhotic thrombocytopenia.

A 2-year old boy was diagnosed with Fanconi anemia (FA) and acute myeloid leukemia (AML). A cell line (termed FA-AML1) was established from blast cells obtained after a second relapse after a successful bone marrow transplant. Histochemical and surface marker analysis confirmed that the cells were derived from the myeloid lineage. Cytogenetic analysis revealed multiple chromosomal aberrations, including a ring 7. Stable proliferation of the cultured cells was absolutely dependent on the presence of granulocyte macrophage colony-stimulating factor or interleukin 3. This is the first AML cell line successfully established from a FA patient. Remarkably, FA-AML1 cells appeared to lack the characteristic cellular FA phenotype, i.e., a hypersensitivity to growth inhibition and chromosomal breakage by the cross-linking agent mitomycin C. Genomic DNA from the patient showed biallelic mutations [8415G>T (K2729N)and 8732C>A (S2835STOP)] in the breast cancer susceptibility gene FANCD1/BRCA2 [N. Howlett et al., Science (Wash. DC), 297: 606-609, 2002]. In the AML cells, however, the 8732C>A nonsense mutation was changed into a missense mutation by a secondary alteration, 8731T>G, resulting in 2835E, which restored the open-reading frame of the gene and could explain the reverted phenotype of these cells. Loss of the FA phenotype by genetic correction of a FA gene mutation during AML progression may be a common late event in the pathogenesis of AML in FA patients, which may be treatment related. This finding suggests a novel mechanistic principle of tumor progression based on the genetic correction of an early caretaker gene defect.

PURPOSE. To examine immune processes in the lacrimal gland of patients with chronic graft-versus-host disease (cGVHD) by evaluating the expression of surface molecules associated with T-cell activation. METHODS. Antibodies to CD4, CD8, CD34, CD40, CD54, CD80, CD86, CD154, and HLA-DR were used for immunohistochemical analysis of lacrimal gland biopsy specimens obtained from nine patients with cGVHD and five with Sjögren's syndrome (SS). The regions of interest were further assessed by transmission electron microscopy. RESULTS. CD4+ and CD8+ T cells were mainly detected in the periductal areas of the glands of patients with cGVHD, but were distributed throughout the acinar areas in patients with SS. In the periductal areas of patients with cGVHD, a subpopulation of CD4+ and CD8+ T cells expressed the activation marker CD154. In addition, CD4+ and CD8+ T cells were colocalized with mononuclear infiltrates and stromal fibroblasts expressing the full component of surface molecules necessary for antigen presentation, including HLA-DR, CD54, CD40, CD80, and CD86. Electron microscopy revealed activated fibroblasts that embraced lymphocytes and macrophages with their processes. Also, there were more CD8+ T cells in the glandular epithelia of patients with cGVHD than in those with SS. Intraepithelial T cells were attached to epithelial cells by several primitive contacts and colocalized with dead cells. CONCLUSIONS. The results strongly suggest that CD4+ and CD8+ T cells in the lacrimal glands of patients with cGVHD are primarily activated in the periductal area through antigenic stimulation by potent antigen-presenting cells and stromal fibroblasts, and exert various effector functions, including cytotoxic effects on glandular epithelial cells.

In vitro T cell proliferative response to an alternative splicing variant of acetylcholine receptor α subunit (AChRα) with the P3A exon-encoded region was examined in peripheral blood samples from 28 myasthenia gravis (MG) patients and 14 healthy donors using recombinant fragments and synthetic peptides. T cells responsive to the P3A region-specific sequences were detected in five MG patients, all of whom were late-onset disease with thymoma, but in none of healthy donors. These autoreactive T cells may be involved in the pathogenic process in a subset of MG patients.

PRAME (Preferentially expressed antigen of melanoma), highly expressed in various solid tumor cells and normal testis, was first isolated as a human melanoma antigen recognized by cytotoxic T cells (CTL). This gene was also expressed in some of the hematological malignancies, including acute myelogenous leukemia (AML) and multiple myeloma. We and others have extensively evaluated the PRAME expression in various hematological malignancies and demonstrated high expression of the PRAME gene in subsets of AML, chronic myelogenous leukemia, acute lymphocytic leukemia, lymphoma and multiple myeloma. In addition, we have demonstrated that PRAME was a useful marker for detection of minimal residual disease (MRD) in patients with leukemia, particularly those leukemias in which tumor specific markers are currently unavailable. Since PRAME was first identified as a tumor antigen recognized by T cells, the possibility that PRAME is a leukemia antigen recognized by T cells was evaluated, and it was found that PRAME-positive leukemia cell lines and fresh leukemia cells were susceptible to lysis by the PRAME-specific CTL. Five CTL epitopes associated with either HLA-A*0201 or HLA-A*2402 have recently been identified. It is, therefore, an attractive strategy to apply PRAME specific immunotherapy on patients with PRAME positive leukemia in MRD condition.

The potential immunosuppressive effect of an anti-CD154 monoclonal antibody (mAb) on the pathogenic autoreactive T-cell response was evaluated using an in vitro culture system with glycoprotein IIb/IIIa (GPIIb/IIIa)-reactive T cells from patients with immune thrombocytopenic purpura (ITP). The anti-CD154 mAb did not inhibit T-cell proliferation, but suppressed anti-GPIIb/IIIa antibody production, in bulk peripheral blood mononuclear cell cultures stimulated with GPIIb/IIIa. Repeated antigenic stimulation of GPIIb/IIIa-reactive CD4+ T-cell lines in the presence of anti-CD154 mAb resulted in the loss of proliferative capacity and helper function for promoting anti-GPIIb/IIIa antibody production. These anergic T-cell lines showed a cytokine profile of low interferon γ and high interleukin 10 and suppressed anti-GPIIb/IIIa antibody production. Our results indicate that blockade of the CD40/CD154 interaction induces generation of autoantigen-specific anergic CD4+ T cells with regulatory function and could be a therapeutic option for suppressing pathogenic autoimmune responses in patients with ITP.

Here we developed an effective therapeutic approach using a replication-conditional mutant of herpes simplex virus (HSV), G207, for the treatment of metastatic tumors in the immunologically privileged central nervous system. An experimental model of brain metastasis was developed using BALB/c mice that harbored both intracranial (i.c.) and subcutaneous (s.c.) mouse CT26 colon adenocarcinoma tumors. Intratumoral injections of G207 into s.c. tumors elicited cytotoxic T-cell responses not only to HSV but also to a tumor antigen; however, only a limited antitumor effect was observed on metastatic brain tumors. To improve this antitumor effect, G207 was also injected into the brain tumor. After intratumoral injections of G207 into both i.c. and s.c. CT26 tumors, a significant antitumor effect was observed in the metastatic brain tumors. This therapeutic efficacy was absent in athymic mice, indicating that the antitumor effect could be mediated by T cells. Cytotoxic T-cell responses to HSV and the tumor antigen were induced by injections of G207 into i.c. and s.c. CT26 tumors. These results suggest that HSV-infected brain tumors may be efficiently eliminated by the induced anti-HSV T cells as well as by antitumor T cells. Therefore, this strategy of immuno-viral therapy, involving direct viral oncolytic activities and inducing antitumor and antiviral immune responses, may be useful for the treatment of tumors in the immunologically privileged central nervous system.

To establish a simple and reliable method to assess the behavioral function after spinal cord injury (SCI) in mice, the authors used an automated animal movement analysis system, SCANET. Two different SCI lesions were created in adult female BALB/c and C57BL/6 mice by transecting both the posterior columns and the left lateral and anterior funiculi or only the left lateral and anterior funiculi at T-8. Control mice underwent laminectomy only. The SCANET system consists of a cage equipped with two crossing sensor frames arranged at different heights, by which small (MI) and large (M2) horizontal movements and the vertical movement involved in rearing (RG) can be monitored. The authors assessed locomotor function by determining the M1, M2, and RG scores; to this end, they used the SCANET system and a previously established behavior test, the 21-point open-field Basso-Beattie-Bresnahan (BBB) Locomotor Rating Scale. The results indicated that the RG scores were significantly and consistently different between the spinal cord-injured and control mice, irrespective of the mouse strain or injury model, but that MI and M2 scores were not. Moreover, there was a statistically positive correlation between the RG score and the BBB Scale score. For the assessment of locomotor function after SCI, use of the SCANET sytem in behavioral analysis is simple and the method is highly reproducible. The analysis of vertical movement is useful for assessing the recovery of limb function in mice following thoracic hemisection.

In this study, we investigated the therapeutic efficacy of a replication-conditional mutant HSV, G207, for the treatment of liver metastasis of colon carcinoma. Three liver metastasis models in syngeneic BALB/c mice were developed: (i) splenic injection, (ii) splenic and subcutaneous (s.c.) injection, and (iii) orthotopic implantation of CT26 colon carcinoma. In the splenic injection model, G207 was injected into the established splenic tumor on day 7. In the splenic and s.c. injection model, G207 were injected into the established s.c. tumor on days 5 and 8. In the orthotopic implantation model, a piece of CT26 tumor tissue was transplanted onto the wall of the cecum and G207 was injected in the established cecum tumor on day 7. On day 21 or 28, animals were sacrificed and liver metastases were evaluated. In all three models in immunocompetent mice, liver metastases were significantly reduced by intratumoral inoculation with G207 compared to the control. In athymic mice, however, there was no significant therapeutic effect of intratumoral inoculation with G207 on liver metastases. Tumor-specific cytotoxic T-lymphocyte responses were induced in mice treated with G207 in the orthotopic implantation model. These results suggest that intratumoral inoculation of G207, as an in situ cancer vaccine, can be an effective approach against liver metastasis of colon cancer and the efficacy involves tumor-specific T-cell responses.