Sialyl Lewis X Defines an Activated and Functional Regulatory T Cell Subpopulation in Mice

Attempts have been made to elucidate the functional markers of regulatory T cells (Tregs), CD4+Foxp3+ T cells with an immunosuppressive function. Sialyl Lewis X (sLex), a tetrasaccharide Ag, is involved in leukocyte trafficking as selectin ligands and is a marker of highly differentiated Tregs in humans. However, the importance of sLex in murine Tregs remains unknown. In this study, we report that sLex defines the activated and functional subset of murine Tregs. The contact hypersensitivity model showed that murine Tregs strongly express sLex upon activation, accompanied by functional Treg marker elevation, such as Foxp3, CD25, CD103, CD39, and granzyme B. RNA sequencing analysis revealed sLex-positive (sLex+) Tregs expressed genes involved in Treg function at a higher level than sLex-negative (sLex-) Tregs. Using an in vitro suppression assay, we found that sLex+ Tregs could more efficiently suppress naive CD4+ T cell proliferation than sLex- Tregs. In the murine contact hypersensitivity elicitation model, the topical sLex+ Treg injection into the ears suppressed ear inflammation more efficiently than that of sLex- Tregs. Our results indicate that sLex could serve as a unique surface marker of activated and functional Tregs with immunosuppressive functions in mice.

CPT-11 mitigates autoimmune diseases by suppressing effector T cells without affecting long-term anti-tumor immunity

The incidence of autoimmune diseases has significantly increased over the past 20 years. Excessive host immunoreactions and disordered immunoregulation are at the core of the pathogenesis of autoimmune diseases. The traditional anti-tumor chemotherapy drug CPT-11 is associated with leukopenia. Considering that CPT-11 induces leukopenia, we believe that it is a promising drug for the control of autoimmune diseases. Here, we show that CPT-11 suppresses T cell proliferation and pro-inflammatory cytokine production in healthy C57BL/6 mice and in complete Freund's adjuvant-challenged mice. We found that CPT-11 effectively inhibited T cell proliferation and Th1 and Th17 cell differentiation by inhibiting glycolysis in T cells. We also assessed CPT-11 efficacy in treating autoimmune diseases in models of experimental autoimmune encephalomyelitis and psoriasis. Finally, we proved that treatment of autoimmune diseases with CPT-11 did not suppress long-term immune surveillance for cancer. Taken together, these results show that CPT-11 is a promising immunosuppressive drug for autoimmune disease treatment.

Prevention of experimental autoimmune encephalomyelitis by targeting 6-sulfo sialyl Lewis X glycans involved in lymphocyte homing

Lymphocyte homing to peripheral lymph nodes (PLN) is critical for immune surveillance. However, autoimmune diseases such as multiple sclerosis (MS) can occur due to excessive immune responses in the PLN. Here we show that 6-sulfo sialyl Lewis X (6-sulfo sLex) glycans on high endothelial venules that function as ligands for l-selectin on lymphocytes play a critical role in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model of MS. In N-acetylglucosamine-6-O-sulfotransferase (GlcNAc6ST)-1 and GlcNAc6ST-2 double-knockout mice lacking the expression of 6-sulfo sLeX glycans, the EAE symptoms and the numbers of effector Th1 and Th17 cells in the draining lymph nodes (dLN) and spinal cords (SC) were significantly reduced. To determine whether 6-sulfo sLeX could serve as a target for MS, we also examined the effects of anti-glycan monoclonal antibody (mAb) SF1 against 6-sulfo sLeX in EAE. Administration of mAb SF1 significantly reduced EAE symptoms and the numbers of antigen-specific effector T cells in the dLN and SC in association with suppression of critical genes including Il17a and Il17f that are involved in the pathogenesis of EAE. Taken together, these results suggest that 6-sulfo sLeX glycan would serve as a novel target for MS.

Opposing functions of circadian protein DBP and atypical E2F family E2F8 in anti-tumor Th9 cell differentiation

Interleukin-9 (IL-9)-producing CD4⁺ T helper cells (Th9) have been implicated in allergy/asthma and anti-tumor immunity, yet molecular insights on their differentiation from activated T cells, driven by IL-4 and transforming growth factor-beta (TGF-β), is still lacking. Here we show opposing functions of two transcription factors, D-binding protein (DBP) and E2F8, in controlling Th9 differentiation. Specifically, TGF-β and IL-4 signaling induces phosphorylation of the serine 213 site in the linker region of the Smad3 (pSmad3L-Ser²¹³) via phosphorylated p38, which is necessary and sufficient for Il9 gene transcription. We identify DBP and E2F8 as an activator and repressor, respectively, for Il9 transcription by pSmad3L-Ser²¹³. Notably, Th9 cells with siRNA-mediated knockdown for Dbp or E2f8 promote and suppress tumor growth, respectively, in mouse tumor models. Importantly, DBP and E2F8 also exhibit opposing functions in regulating human TH9 differentiation in vitro. Thus, our data uncover a molecular mechanism of Smad3 linker region-mediated, opposing functions of DBP and E2F8 in Th9 differentiation.

STAP-2 Is a Novel Positive Regulator of TCR-Proximal Signals

TCR ligation with an Ag presented on MHC molecules promotes T cell activation, leading to the selection, differentiation, and proliferation of T cells and cytokine production. These immunological events are optimally arranged to provide appropriate responses against a variety of pathogens. We here propose signal-transducing adaptor protein-2 (STAP-2) as a new positive regulator of TCR signaling. STAP-2-deficient T cells showed reduced, whereas STAP-2-overexpressing T cells showed enhanced, TCR-mediated signaling and downstream IL-2 production. For the mechanisms, STAP-2 associated with TCR-proximal CD3ζ immunoreceptor tyrosine activation motifs and phosphorylated LCK, resulting in enhancement of their binding after TCR stimulation. In parallel, STAP-2 expression is required for full activation of downstream TCR signaling. Importantly, STAP-2-deficient mice exhibited slight phenotypes of CD4⁺ T-cell-mediated inflammatory diseases, such as experimental autoimmune encephalomyelitis, whereas STAP-2-overexpressing transgenic mice showed severe phenotypes of these diseases. Together, STAP-2 is an adaptor protein to enhance TCR signaling; therefore, manipulating STAP-2 will have an ability to improve the treatment of patients with autoimmune diseases as well as the chimeric Ag receptor T cell therapy.

Single-Cell Analysis Revealed the Role of CD8+ Effector T Cells in Preventing Cardioprotective Macrophage Differentiation in the Early Phase of Heart Failure

Heart failure is a complex clinical syndrome characterized by insufficient cardiac function. Heart-resident and infiltrated macrophages have been shown to play important roles in the cardiac remodeling that occurs in response to cardiac pressure overload. However, the possible roles of T cells in this process, have not been well characterized. Here we show that T cell depletion conferred late-stage heart protection but induced cardioprotective hypertrophy at an early stage of heart failure caused by cardiac pressure overload. Single-cell RNA sequencing analysis revealed that CD8+T cell depletion induced cardioprotective hypertrophy characterized with the expression of mitochondrial genes and growth factor receptor genes. CD8+T cells regulated the conversion of both cardiac-resident macrophages and infiltrated macrophages into cardioprotective macrophages expressing growth factor genes such as Areg, Osm, and Igf1, which have been shown to be essential for the myocardial adaptive response after cardiac pressure overload. Our results demonstrate a dynamic interplay between cardiac CD8+T cells and macrophages that is necessary for adaptation to cardiac stress, highlighting the homeostatic functions of resident and infiltrated macrophages in the heart.

The Curcumin Analog GO-Y030 Controls the Generation and Stability of Regulatory T Cells

Regulatory T cells (Tregs) play a crucial role in preventing antitumor immune responses in cancer tissues. Cancer tissues produce large amounts of transforming growth factor beta (TGF-β), which promotes the generation of Foxp3+ Tregs from naïve CD4+ T cells in the local tumor microenvironment. TGF-β activates nuclear factor kappa B (NF-κB)/p300 and SMAD signaling, which increases the number of acetylated histones at the Foxp3 locus and induces Foxp3 gene expression. TGF-β also helps stabilize Foxp3 expression. The curcumin analog and antitumor agent, GO-Y030, prevented the TGF-β-induced generation of Tregs by preventing p300 from accelerating NF-κB-induced Foxp3 expression. Moreover, the addition of GO-Y030 resulted in a significant reduction in the number of acetylated histones at the Foxp3 promoter and at the conserved noncoding sequence 1 regions that are generated in response to TGF-β. In vivo tumor models demonstrated that GO-Y030-treatment prevented tumor growth and reduced the Foxp3+ Tregs population in tumor-infiltrating lymphocytes. Therefore, GO-Y030 exerts a potent anticancer effect by controlling Treg generation and stability.

Reprogramming of Th1 cells into regulatory T cells through rewiring of the metabolic status

T helper type 1 (Th1) cells form one of the most stable CD4 T-cell subsets, and direct conversion of fully differentiated Th1 to regulatory T (Treg) cells has been poorly investigated. Here, we established a culture method for inducing Foxp3 from Th1 cells of mice and humans. This is achieved simply by resting Th1 cells without T-cell receptor ligation before stimulation in the presence of transforming growth factor-beta (TGF-β). We named the resulting Th1-derived Foxp3+ cells Th1reg cells. Mouse Th1reg cells showed an inducible Treg-like phenotype and suppressive ability both in vitro and in vivo. Th1reg cells could also be induced from in vivo-developed mouse Th1 cells. Unexpectedly, the resting process enabled Foxp3 expression not through epigenetic changes at the locus, but through metabolic change resulting from reduced mammalian target of rapamycin complex 1 (mTORC1) activity. mTORC1 suppressed TGF-β-induced phosphorylation of Smad2/3 in Th1 cells, which was restored in rested cells. Our study warrants future research aiming at development of immunotherapy with Th1reg cells.

Combination of apoptotic T cell induction and self-peptide administration for therapy of experimental autoimmune encephalomyelitis

BACKGROUND

Clinical trials on multiple sclerosis with repeated injections of monoclonal antibodies depleting CD4⁺ T cells have not resulted in much success as a disease therapy. Here, we developed an immunotherapy for EAE in mice by combining a transient depletion of T cells together with the administration of neuron derived peptides.

METHODS

EAE was induced in SJL and C57BL/6 mice, by proteolipid protein peptide PLP_139-151 (pPLP) and myelin-oligodendrocyte glycoprotein MOG_35-55 (pMOG) peptides, respectively. Anti-CD4 and anti-CD8 antibody were injected intraperitoneally before or after peptide immunization. EAE scores were evaluated and histology data from brain and spinal cord were analyzed. Splenocytes were isolated and CD4⁺, CD4⁺CD25^- and CD4⁺CD25⁺ T cells were purified and cultured in the presence of either specific peptides or anti-CD3 antibody and proliferation of T cells as well as cytokines in supernatant were assessed.

FINDINGS

This experimental treatment exhibited therapeutic effects on mice with established EAE in pPLP-susceptible SJL mice and pMOG-susceptible C57BL/6 mice. Mechanistically, we revealed that antibody-induced apoptotic T cells triggered macrophages to produce TGFβ, and together with administered auto-antigenic peptides, generated antigen-specific Foxp3⁺ regulatory T cells (T_reg cells) in vivo.

INTERPRETATION

We successfully developed a specific immunotherapy to EAE by generating autoantigen-specific T_reg cells. These findings have overcome the drawbacks of long and repeated depletion of CD4⁺ T cells, but also obtained long-term immune tolerance, which should have clinical implications for the development of a new effective therapy for multiple sclerosis. FUND: This research was supported by the Intramural Research Program of the NIH, NIDCR.

Negative Regulation of Cytokine Signaling in Immunity

Cytokines are key modulators of immunity. Most cytokines use the Janus kinase and signal transducers and activators of transcription (JAK-STAT) pathway to promote gene transcriptional regulation, but their signals must be attenuated by multiple mechanisms. These include the suppressors of cytokine signaling (SOCS) family of proteins, which represent a main negative regulation mechanism for the JAK-STAT pathway. Cytokine-inducible Src homology 2 (SH2)-containing protein (CIS), SOCS1, and SOCS3 proteins regulate cytokine signals that control the polarization of CD4+ T cells and the maturation of CD8+ T cells. SOCS proteins also regulate innate immune cells and are involved in tumorigenesis. This review summarizes recent progress on CIS, SOCS1, and SOCS3 in T cells and tumor immunity.

Improvement of Foxp3 stability through CNS2 demethylation by TET enzyme induction and activation

Since induced regulatory T cells (iTregs) can be produced in a large quantity in vitro, these cells are expected to be clinically useful to induce immunological tolerance in various immunological diseases. Foxp3 (Forkhead box P3) expression in iTregs is, however, unstable due to the lack of demethylation of the CpG island in the conserved non-coding sequence 2 (CNS2) of the Foxp3 locus. To facilitate the demethylation of CNS2, we over-expressed the catalytic domain (CD) of the ten-eleven translocation (TET) protein, which catalyzes the steps of the iterative demethylation of 5-methylcytosine. TET-CD over-expression in iTregs resulted in partial demethylation of CNS2 and stable Foxp3 expression. We also discovered that TET expression was enhanced under low oxygen (5%) culture conditions, which facilitated CNS2 DNA demethylation and stabilization of Foxp3 expression in a TET2- and TET3-dependent manner. In combination with vitamin C treatment, which has been reported to enhance TET catalytic activity, iTregs generated under low oxygen conditions retained more stable Foxp3 expression in vitro and in vivo and exhibited stronger suppression activity in a colitis model compared with untreated iTregs. Our data indicate that the induction and activation of TET enzymes in iTregs would be an effective method for Treg-mediated adoptive immunotherapy.

TRAF6-TAK1 signaling drives Th9 differentiation

Naive CD4+ T cells differentiate into different subsets depending upon milieu of cytokine exposure. Interleukin-9 (IL-9)-producing CD4+ helper T cells (Th9 cells) are induced from naive CD4+ T cells by transforming growth factor-β (TGF-β) together with interleukin-4 (IL-4) during stimulation of the T cell antigen receptor (TCR) in vitro. The master regulator of Th9 cells as well as the molecular mechanisms by which TGF-β signals and IL-4 signals co-operatively drive the differentiation of Th9 cells are not fully understood.

Previously, our group has reported that inhibitor of DNA-binding 3 (Id3), a transcription factor which inhibits DNA-binding of basic helix-loop-helix protein, such as E2A, controls the TGF-β-mediated differentiation of Th9 cells. We found that this process required activation of the kinase transforming growth factor beta-activated kinase 1 (TAK1). In addition, RNA-seq revealed that tumor necrosis factor receptor-associated factor 6 (TRAF6) was highly up-regulated by TGF-β together with IL-4 in CD4+ T cells. Since TRAF6 is one of the TAK-1 activator, we hypothesized TRAF6 is also involved in the differentiation of Th9 cells. We found that the expression and ubiquitination of TRAF6 was upregulated under the Th9 differentiation condition and it resulted in activation of TAK1. These regulations were attenuated both in TGF-β and Smad3 deficient mice, suggesting TRAF6-TAK1 signaling is involved in TGF-β-mediated Th9 differentiation.

Inhibition of Nr4a Receptors Enhances Antitumor Immunity by Breaking Treg-Mediated Immune Tolerance

Enhanced infiltration of regulatory T cells (Treg) into tumor tissue is detrimental to patients with cancer and is closely associated with poor prognosis as they create an immunosuppressive state that suppresses antitumor immune responses. Therefore, breaking Treg-mediated immune tolerance is important when considering cancer immunotherapy. Here, we show that the Nr4a nuclear receptors, key transcription factors maintaining Treg genetic programs, contribute to Treg-mediated suppression of antitumor immunity in the tumor microenvironment. Mice lacking Nr4a1 and Nr4a2 genes specifically in Tregs showed resistance to tumor growth in transplantation models without exhibiting any severe systemic autoimmunity. The chemotherapeutic agent camptothecin and a common cyclooxygenase-2 inhibitor were found to inhibit transcriptional activity and induction of Nr4a factors, and they synergistically exerted antitumor effects. Genetic inactivation or pharmacologic inhibition of Nr4a factors unleashed effector activities of CD8⁺ cytotoxic T cells and evoked potent antitumor immune responses. These findings demonstrate that inactivation of Nr4a in Tregs breaks immune tolerance toward cancer, and pharmacologic modulation of Nr4a activity may be a novel cancer treatment strategy targeting the immunosuppressive tumor microenvironment.Significance: This study reveals the role of Nr4a transcription factors in Treg-mediated tolerance to antitumor immunity, with possible therapeutic implications for developing effective anticancer therapies. Cancer Res; 78(11); 3027-40. ©2018 AACR.

Induction and maintenance of regulatory T cells by transcription factors and epigenetic modifications

Regulatory T cells (Tregs) are an essential cell subset for the maintenance of immune homeostasis. Foxp3 (Forkhead box P3) is the Treg master gene which is essential for immune suppressing activity. In addition, Tregs are characterized by a distinct pattern of gene expression, including upregulation of immune-suppressive genes and silencing of inflammatory genes. The molecular mechanisms of Treg development and maintenance have been intensively investigated. Tregs are characterized by expression of the transcription factor Foxp3. Several intronic enhancers and a promoter at the Foxp3 gene locus were shown to play important roles in Treg differentiation. The enhancers have been designated as conserved non-coding sequences (CNSs) 0, 1, 2, and 3. We showed that the transcription factors Nr4a and Smad2/3 are essential for the development of thymic Tregs and induced Tregs, respectively. Recently, Treg-specific DNA demethylation has been shown to play an important role in Treg stability. DNA demethylation of CNS2 has been implicated in Treg stability, and recent reports have revealed that the ten-eleven translocation (Tet) family of demethylation factor plays an important role in CpG demethylation at CNS2. This article reviews the recent progress on the roles of transcription factors and epigenetic modifications in the differentiation, maintenance, and function of Tregs.

SOCS1 Is a Key Molecule That Prevents Regulatory T Cell Plasticity under Inflammatory Conditions

We previously showed that regulatory T cells (Tregs) from T cell-specific Socs1-deficient mice (Socs1^fl/flLck-Cre⁺ mice) easily convert into Th1- or Th17-like cells (ex-Tregs), which lose Foxp3 expression and suppressive functions in vivo. Because Tregs in Socs1^fl/flLck-Cre⁺ mice are constantly exposed to a large amount of inflammatory cytokines produced by non-Tregs in vivo, in this study we analyzed Treg-specific Socs1-deficient mice (Socs1^fl/flFoxp3^YFP-Cre mice). These mice developed dermatitis, splenomegaly, and lymphadenopathy that were much milder than those in Socs1^fl/flLck-Cre⁺ mice. A fate mapping study revealed that Socs1 deficiency accelerated the conversion of Tregs to Foxp3^-IFN-γ⁺ ex-Tregs in the tumor microenvironment and suppressed tumor growth. When transferred into Rag2^-/- mice, Tregs from Socs1^fl/flLck-Cre⁺ mice easily lost Foxp3 expression, whereas those from Socs1^fl/flFoxp3^YFP-Cre mice maintained Foxp3 expression. Although Tregs from Socs1^fl/flLck-Cre⁺ mice produced IFN-γ after a 3-d culture in response to anti-CD3/CD28 Ab stimulation in vitro, Tregs from Socs1^fl/flFoxp3^YFP-Cre mice did not. This finding suggested that the inflammatory conditions in Socs1^fl/flLck-Cre⁺ mice modified the born nature of Socs1-deficient Tregs. To investigate this mechanism, Tregs from Socs1^fl/flFoxp3^YFP-Cre mice were cultured with APCs from Socs1^fl/flLck-Cre⁺ mice. These APCs facilitated STAT4 phosphorylation, IFN-γ production, and loss of Foxp3 expression in Tregs from Socs1^fl/flFoxp3^YFP-Cre mice in an IL-12-dependent manner. The results indicate that Socs1-deficient Tregs tend to convert into ex-Tregs under the inflammatory conditions in which APCs are highly activated, and that SOCS1 could be a useful target for enhancement of anti-tumor immunity.

Notch-mediated conversion of activated T cells into stem cell memory-like T cells for adoptive immunotherapy

Adoptive T-cell immunotherapy is a promising approach to cancer therapy. Stem cell memory T (T_SCM) cells have been proposed as a class of long-lived and highly proliferative memory T cells. CD8⁺ T_SCM cells can be generated in vitro from naive CD8⁺ T cells via Wnt signalling; however, methods do not yet exist for inducing T_SCM cells from activated or memory T cells. Here, we show a strategy for generating T_SCM-like cells in vitro (iT_SCM cells) from activated CD4⁺ and CD8⁺ T cells in mice and humans by coculturing with stromal cells that express a Notch ligand. iT_SCM cells lose PD-1 and CTLA-4 expression, and produce a large number of tumour-specific effector cells after restimulation. This method could therefore be used to generate antigen-specific effector T cells for adoptive immunotherapy.

Tumour-specific T cells can be expanded in vitro and adoptively transferred for therapy, but this strategy is limited by induction of short-lived T cell populations. Here the authors activate Notch signalling in cultured mouse or human T cells, resulting in the production of a long-lived stem cell memory T cell population that can fight tumours in mice.

Stabilization of Foxp3 expression by CRISPR-dCas9-based epigenome editing in mouse primary T cells

Background

Epigenome editing is expected to manipulate transcription and cell fates and to elucidate the gene expression mechanisms in various cell types. For functional epigenome editing, assessing the chromatin context-dependent activity of artificial epigenetic modifier is required.

Results

In this study, we applied clustered regularly interspaced short palindromic repeats (CRISPR)-dCas9-based epigenome editing to mouse primary T cells, focusing on the Forkhead box P3 (Foxp3) gene locus, a master transcription factor of regulatory T cells (Tregs). The Foxp3 gene locus is regulated by combinatorial epigenetic modifications, which determine the Foxp3 expression. Foxp3 expression is unstable in transforming growth factor beta (TGF-β)-induced Tregs (iTregs), while stable in thymus-derived Tregs (tTregs). To stabilize Foxp3 expression in iTregs, we introduced dCas9-TET1CD (dCas9 fused to the catalytic domain (CD) of ten-eleven translocation dioxygenase 1 (TET1), methylcytosine dioxygenase) and dCas9-p300CD (dCas9 fused to the CD of p300, histone acetyltransferase) with guide RNAs (gRNAs) targeted to the Foxp3 gene locus. Although dCas9-TET1CD induced partial demethylation in enhancer region called conserved non-coding DNA sequences 2 (CNS2), robust Foxp3 stabilization was not observed. In contrast, dCas9-p300CD targeted to the promoter locus partly maintained Foxp3 transcription in cultured and primary T cells even under inflammatory conditions in vitro. Furthermore, dCas9-p300CD promoted expression of Treg signature genes and enhanced suppression activity in vitro.

Conclusions

Our results showed that artificial epigenome editing modified the epigenetic status and gene expression of the targeted loci, and engineered cellular functions in conjunction with endogenous epigenetic modification, suggesting effective usage of these technologies, which help elucidate the relationship between chromatin states and gene expression.

Electronic supplementary material

The online version of this article (doi:10.1186/s13072-017-0129-1) contains supplementary material, which is available to authorized users.

TET2 and TET3 regulate stability and function of regulatory T cells

Regulatory T cells (Tregs) play a pivotal role in regulating immune response and maintaining immunological tolerance, and are characterized by the expression of Foxp3. Thymus-derived Tregs have been shown to be relatively stable compared with iTregs generated from naive T cells with TGFβ in vitro. Treg stability is maintained by the epigenetic modification, such as DNA demethylation of Treg-specific demethylation regions (TSDRs) during Treg development in the thymus. In fact, the TSDRs of iTreg are hypermethylated. Although DNA demethylase, ten-eleven translocation (TET) family proteins have been proposed to be involved in the DNA demethylation of TSDRs, actual contribution of TET family proteins in Treg stability and function remains to be elucidated. To investigate the role of TET proteins in Tregs, we generated Treg-specific Tet-deficient (Foxp3YFPCre+Tet2f/fTet3f/f; FDKO) mice. FDKO mice died at an average of 20 weeks of age with splenomegaly and lymph adenopathy accompanied by uncontrolled activation of T cells and B cells. These FDKO mice developed inflammation in the gut, and both Foxp3+ and Foxp3− T cells were expanded and produced high levels of IL-17 especially in gut mucosa and mesenteric lymph nodes. Transfer experiment of FDKO Tregs into lymphopenic mice revealed that Foxp3 expression in FDKO Tregs was unstable and Treg cells which have lost their Foxp3 expression were accumulated. TSDRs of FDKO Tregs were hyper-, but not completely, methylated compared with WT Tregs, indicating that there are TET2/3 dependent and independent mechanisms for TSDR demethylation. These data indicate that TET2 and TET3 are redundantly involved in TSDR demethylation and are important for the stability and homeostasis of Tregs.

Role of ATP as a Key Signaling Molecule Mediating Radiation-Induced Biological Effects

Adenosine triphosphate (ATP) serves as a signaling molecule for adaptive responses to a variety of cytotoxic agents and plays an important role in mediating the radiation stress-induced responses that serve to mitigate or repair the injurious effects of γ radiation on the body. Indeed, low doses of radiation may have a net beneficial effect by activating a variety of protective mechanisms, including antitumor immune responses. On the other hand, ATP signaling may be involved in the radiation resistance of cancer cells. Here, focusing on our previous work, we review the evidence that low-dose γ irradiation (0.25-0.5 Gy) induces release of extracellular ATP, and that the released ATP mediates multiple radiation-induced responses, including increased intracellular antioxidant synthesis, cell-mediated immune responses, induction of DNA damage repair systems, and differentiation of regulatory T cells.

Antibiotics in neonatal life increase murine susceptibility to experimental psoriasis

Psoriasis is an inflammatory skin disease affecting ∼2% of the world's population, but the aetiology remains incompletely understood. Recently, microbiota have been shown to differentially regulate the development of autoimmune diseases, but their influence on psoriasis is incompletely understood. We show here that adult mice treated with antibiotics that target Gram-negative and Gram-positive bacteria develop ameliorated psoriasiform dermatitis induced by imiquimod, with decreased pro-inflammatory IL-17- and IL-22-producing T cells. Surprisingly, mice treated neonatally with these antibiotics develop exacerbated psoriasis induced by imiquimod or recombinant IL-23 injection when challenged as adults, with increased IL-22-producing γδ(+) T cells. 16S rRNA gene compositional analysis reveals that neonatal antibiotic-treatment dysregulates gut and skin microbiota in adults, which is associated with increased susceptibility to experimental psoriasis. This link between neonatal antibiotic-mediated imbalance in microbiota and development of experimental psoriasis provides precedence for further investigation of its specific aetiology as it relates to human psoriasis.

The DNA-binding inhibitor Id3 regulates IL-9 production in CD4(+) T cells

The molecular mechanisms by which signaling via transforming growth factor-β (TGF-β) and interleukin 4 (IL-4) control the differentiation of CD4(+) IL-9-producing helper T cells (TH9 cells) remain incompletely understood. We found here that the DNA-binding inhibitor Id3 regulated TH9 differentiation, as deletion of Id3 increased IL-9 production from CD4(+) T cells. Mechanistically, TGF-β1 and IL-4 downregulated Id3 expression, and this process required the kinase TAK1. A reduction in Id3 expression enhanced binding of the transcription factors E2A and GATA-3 to the Il9 promoter region, which promoted Il9 transcription. Notably, Id3-mediated control of TH9 differentiation regulated anti-tumor immunity in an experimental melanoma-bearing model in vivo and also in human CD4(+) T cells in vitro. Thus, our study reveals a previously unrecognized TAK1-Id3-E2A-GATA-3 pathway that regulates TH9 differentiation.

In vivo-generated antigen-specific regulatory T cells treat autoimmunity without compromising antibacterial immune response

Harnessing regulatory T (Treg) cells is a promising approach for treating autoimmune disease. However, inducing antigen-specific Treg cells that target inflammatory immune cells without compromising beneficial immune responses has remained an unmet challenge. We developed a pathway to generate autoantigen-specific Treg cells in vivo, which showed therapeutic effects on experimental autoimmune encephalomyelitis and nonobese diabetes in mice. Specifically, we induced apoptosis of immune cells by systemic sublethal irradiation or depleted B and CD8(+) T cells with specific antibodies and then administered autoantigenic peptides in mice with established autoimmune diseases. We demonstrated mechanistically that apoptotic cells triggered professional phagocytes to produce transforming growth factor-β, under which the autoantigenic peptides directed naïve CD4(+) T cells to differentiate into Foxp3(+) Treg cells instead of into T effector cells in vivo. These antigen-specific Treg cells specifically ameliorated autoimmunity without compromising immune responses to bacterial antigen. We have thus successfully generated antigen-specific Treg cells with therapeutic activity toward autoimmunity. The findings may lead to the development of antigen-specific Treg cell-mediated immunotherapy for multiple sclerosis and type 1 diabetes and also other autoimmune diseases.

Transcriptional factor E2A regulates the differentiation of Th17 cells (69.10)

The molecular mechanisms that direct transcription of the gene encoding the transcription factor RORγt, a master regulator of Th17 cells, remain ill-defined. We previously showed that transcription factor E2A is enriched at the Foxp3 promoter and regulates the differentiation of regulatory T cells in response to TGF-β. Since TGF-β is also required to generate Th17 cells, we hypothesized that E2A might also be involved in the differentiation of Th17 cells. We utilized Id3 deficient mice, as Id3 is reported to inhibit E2A binding to DNA, and found that Id3 deficient mice had a much greater frequency and absolute number of Th17 cells in the lamina propria and Peyer’s patches. In vitro study showed that Id3 deficient CD4(+)CD25(-) naïve T cells showed greater differentiation into Th17 cells in response to TGF-β1 plus IL-6. Treatment with TGF-β1 substantially enriched E2A at the Rorc promoter in naïve CD4(+) T cells. In addition, E2A knockdown by siRNA resulted much less Rorc transcription and IL-17 production in CD4(+) T cells stimulated with TGF-β1 plus IL-6. These data suggest that E2A plays an important role in promoting the RORγt expression through enrichment to Rorc promoter and the consequent Th17 differentiation. We plan to investigate how IL-6-mediated signaling pathway is integrated with E2A-mediated Rorc activation in directing IL-17 production in CD4(+) T cells.

Adenosine A2B receptor antagonist suppresses differentiation to regulatory T cells without suppressing activation of T cells

Extracellular adenosine activates P1 receptors (A(1), A(2A), A(2B), A(3)) on cellular membranes. Here, we investigated the involvement of P1 receptor-mediated signaling in differentiation to regulatory T cells (Treg). Treg were induced in vitro by incubating isolated CD4(+)CD62L(+) naïve murine T cells under Treg-skewing conditions. Antagonists of A(1) and A(2B) receptors suppressed the expression of Foxp3, a specific marker of Treg, and the production of IL-10, suggesting the involvement of A(1) and A(2B) receptors in differentiation to Treg. We also investigated the effect of these antagonists on T cell activation, which is essential for differentiation to Treg, and found that A(1) antagonist, but not A(2B) antagonist, suppressed T cell activation. We conclude that A(1) and A(2B) receptors are both involved in differentiation to Treg, but through different mechanisms. Since A(2B) antagonist blocked differentiation to Treg without suppressing T cell activation, it is possible that blockade of A(2B) receptor would facilitate tumor immunity.

Repeated gamma irradiation attenuates collagen-induced arthritis via up-regulation of regulatory T cells but not by damaging lymphocytes directly

We recently reported that repeated 0.5-Gy gamma irradiation attenuates the pathology of collagen-induced arthritis. In this study, to investigate the mechanism further, we focused on changes in Treg/Th17 cells and changes in the production of antibody against an external antigen in response to gamma irradiation as well as on the radiosensitivity of Treg cells. DBA/1J mice were immunized with type II collagen to induce arthritis and exposed to low-dose gamma rays (0.5 Gy/week for 5 weeks). Production of IL6 and IL17 as well as autoantibody was suppressed by irradiation in the early phase of collagen-induced arthritis. The percentage of Treg cells was significantly increased by irradiation at 4, 6 and 8 weeks after the immunization. We also investigated the effect of repeated gamma radiation on the production of antibodies against an external antigen in ovalbumin-immunized BALB/c mice. We found that repeated 0.5-Gy gamma irradiation enhanced antibody production, accompanied by an increase of the antibody-producing plasma cell population and increased Th2-type cytokine secretion. We also found that the radiosensitivity of Treg cells did not differ from that of other T cells. These results suggest that a major mechanism of attenuation of the pathology of collagen-induced arthritis by repeated 0.5-Gy gamma irradiation is up-regulation of Treg cells concomitantly with suppression of IL6 and IL17 production.

Preoperative estimation of remnant hepatic function using fusion images obtained by (99m)Tc-labelled galactosyl-human serum albumin liver scintigraphy and computed tomography

BACKGROUND

Assessment of hepatic functional reserve is important in hepatic resection. The aim of this study was to evaluate the role of hepatic asialoglycoprotein receptor (ASGP-R) analysis in the preoperative estimation of remnant liver function in liver surgery.

METHODS

One hundred and one patients undergoing hepatic resection for liver tumours were studied. Seventeen patients had preoperative percutaneous transhepatic portal vein embolization (PTPE). Function of the hepatic remnant was estimated before surgery using radioactivity in fusion images of both liver single-photon emission computed tomography and computed tomography scans using (99m)Tc-labelled diethylene triamine penta-acetate-galactosyl-human serum albumin.

RESULTS

All three patients with an ASGP-R concentration below 400 nmol/l and preoperative total amount of receptor in the future remnant liver (R0-remnant) of less than 53.0 nmol per liver died. Two patients with chronic hepatitis and R0-remnant values between 53.0 and 65.0 nmol per liver and a receptor concentration lower than 600 nmol/l developed liver dysfunction. The incidence of liver failure decreased inversely with increasing R0-remnant value.

CONCLUSION

A combination of receptor concentration and the amount of hepatic receptor in the future liver remnant as detected on fusion images is useful in evaluating the risk of postoperative liver failure.

Repeated 0.5-Gy gamma irradiation attenuates experimental autoimmune encephalomyelitis with up-regulation of regulatory T cells and suppression of IL17 production

We recently reported attenuation of autoimmune disease by low-dose gamma irradiation (repeated doses of 0.5 Gy) in MRL-lpr/ lpr mice. Here we studied the effect of low-dose gamma irradiation on experimental autoimmune encephalomyelitis (EAE), which is a rodent model of multiple sclerosis. SJL/J mice were immunized with myelin basic protein for the induction of EAE and were exposed to 0.5 Gy gamma rays once a week for 4 weeks. Radiation suppressed incidence and disease severity scores and delayed the onset of pathological changes. Pro-inflammatory cytokines (IFN-gamma and IL6), autoantibody and CD8+ cytotoxic T cells are involved in the appearance of EAE. Radiation suppressed the increases in these cytokines and the autoantibody production and blocked the increase in the population of CD8+ cytotoxic T cells. Production of IL17 by Th17 cells and/or gammadelta T cells, which plays a crucial role in EAE, was also significantly suppressed by radiation. Furthermore, a significant increase in regulatory T cells, which are involved in suppression of autoimmune disease, was found in irradiated EAE mice. These data suggest that low-dose gamma irradiation attenuates EAE through suppression of pro-inflammatory cytokines, reduction of cytotoxic T cells and induction of regulatory T cells.

Suppressing effect of low-dose gamma-ray irradiation on collagen-induced arthritis

We previously reported attenuation of autoimmune disease by low-dose gamma-ray irradiation in MRL-lpr/lpr mice. Here, we studied the effect of low-dose gamma-ray irradiation on collagen-induced arthritis (CIA) in DBA/1J mice. Mice were immunized with type II collagen, and exposed to low-dose gamma-rays (0.5 Gy per week for 5 weeks). Paw swelling, redness, and bone degradation were suppressed by irradiation, which also delayed the onset of pathological change and reduced the severity of the arthritis. Production of tumor necrosis factor-alpha, interferon-gamma, and interleukin-6, which play important roles in the onset of CIA, was suppressed by the irradiation. The level of anti-type II collagen antibody, which is essential for the onset of CIA, was also lower in irradiated CIA mice. The population of plasma cells was increased in CIA mice, but irradiation blocked this increase. Since regulatory T cells are known to be involved in suppression of autoimmune disease, the population of CD4(+)CD25(+)Foxp3(+) regulatory T cells was measured. Intriguingly, a significant increase of these regulatory T cells was found in irradiated CIA mice. Overall, our data suggest that low-dose gamma-ray irradiation could attenuate CIA through suppression of pro-inflammatory cytokines and autoantibody production, and induction of regulatory T cells.

[Lung abscess which ruptured during the medical treatment of lung abscess; report of a case]

63-year-old man was admitted to our hospital with fever and cough for about 2 months. Laboratory data showed marked inflammatory changes, and chest computed tomography (CT) scans revealed right-sided hydrothorax, atelectasis of the right middle lobe, and a cystic mass in the right middle lobe. We diagnosed the patients as having lung abscess and empyema. Following the intravenous antibiotic chemotherapy, symptoms and laboratory data showed the improvement, however, on the 11th hospital day, he developed high fever again. A chest CT showed pneumopyothorax suggesting the rupture of lung abscess. Since the chest tube drainage was ineffective, open chest surgery was performed. Curettage of both thoracic and abscess cavity with closure of air leakage successfully cured the pyothorax.

Effects of zinc deficiency/zinc supplementation on ammonia metabolism in patients with decompensated liver cirrhosis

Hepatic encephalopathy is one of the major complications in decompensated liver cirrhosis. The current study was conducted to clarify the mechanisms of zinc deficiency in liver cirrhosis and its involvement in hepatic encephalopathy via ammonia metabolism. Ten patients each with compensated or decompensated liver cirrhosis and 11 healthy volunteers were enrolled in the study. Serum zinc levels and its daily urinary excretion were measured, an oral zinc-tolerance test was performed to examine zinc malabsorption, and the effects of diuretics on zinc excretion and of zinc supplementation on ammonia metabolism in the skeletal muscle were studied. The mean serum zinc levels in patients with decompensated liver cirrhosis were found to be significantly lower than the levels in controls and patients with compensated liver cirrhosis. The serum zinc levels were inversely correlated with blood ammonia in the fasting state. In the oral zinc-tolerance test, the percent increase in serum zinc levels 120 and 180 min after ingestion was less in cirrhotic patients than in controls. A diuretic administration resulted in a significant reduction in serum zinc levels. An increased uptake of ammonia by and an increased release of glutamine from leg skeletal muscle after oral supplementation of zinc sulfate were evident. Taken together, zinc deficiency in decompensated cirrhotic patients appears to be due to low absorption and to high urinary excretion, for which excessive diuretic administration is, in part, responsible, and zinc supplementation might play an important role in the prevention of hepatic encephalopathy by activating glutamine synthetase.

Actual invasive potential of human hepatocellular carcinoma revealed by in situ gelatin zymography

BACKGROUND

The matrix-degrading proteinases are believed to play an important role in the invasion and metastasis of hepatocellular carcinoma (HCC), but no one has ever seen the in situ matrix-degrading activity in HCCs.

PURPOSE

To demonstrate the cellular localization of actual gelatinolytic activity and to investigate the invasive potential of human HCC.

EXPERIMENTAL DESIGN

HCC cases (30) were subjected to in situ gelatin zymography and SDS-gelatin gel zymogram.

RESULTS

In situ gelatin zymography revealed a heterogeneous gelatinolytic activity in HCC cells, as well as stromal cells of noncancerous livers. The gelatinolytic intensity was stronger in 15 HCC nodules than in the corresponding noncancerous livers and was significantly associated with the cancer invasion to the capsule of the HCCs and to the portal veins. An intense gelatinolytic activity was detected in HCC cells in the front of tumor invasion. SDS-gelatin gel zymogram revealed gelatinases A and B that were mostly in latent forms.

CONCLUSIONS

The present study demonstrates high gelatinolytic activity at the invasive front of HCCs at a cellular level and that HCC has an invasive potential with the gelatin (matrix)-degrading metalloproteinases. Furthermore, it suggests the importance of the activation mechanism of gelatinolytic enzymes in the invasion and metastasis of HCCs.

The formation of capsule and septum in human hepatocellular carcinoma

The formation of fibrous capsule around the cancer nodule and of the septum in the tumor is frequently observed with the development of hepatocellular carcinoma (HCC). We aimed to clarify how the capsule and septum were formed during the growth of HCC. Liver samples surgically resected from 25 patients with HCC were studied with in situ hybridization for type-I, -III, and -IV procollagen. Type-I and -III procollagen-expressing cells, mostly alpha-smooth muscle actin (SMA)-positive, were increased in the fibrous capsule and in the septum between HCC nodules. These cells were also found at the invasion front of HCC and around the necrotic cancer tissues. Type-IV procollagen gene expression was mainly observed in mesenchymal cells localized in both HCCs and non-cancerous liver. Cancer cells or hepatocytes did not express any of these procollagen genes. The present study reveals that the capsule and septum are mainly formed by alpha-SMA-positive mesenchymal cells at the interface between two different tissues (e.g., cancer nodule vs non-cancerous liver or another cancer nodule). The wound healing occurs even in HCC. The capsule formation may result from interaction between tumor and host liver and interfere the growth and invasion of HCC.

Serum interferon-gamma-inducing factor/IL-18 levels in primary biliary cirrhosis

Primary biliary cirrhosis is an autoimmune disease of the liver in which T helper 1 cytokines predominate over those of T helper 2 in the pathogenesis. Interleukin- 18 (IL-18), for which the gene was recently cloned, is a novel T helper 1 cytokine, which augments interferon-gamma production. We designed this study to clarify the role of IL-18 in primary biliary cirrhosis and to examine whether serum IL-18 level can be a prognostic indicator for the disease. Serum IL-18 levels were measured using an enzyme linked immuno sorbent assay with mouse monoclonal antibodies. Twenty-two healthy volunteers, 31 patients with primary biliary cirrhosis (Scheuer's stage I, 13; II, 10; and IV, 8), 20 patients with autoimmune hepatitis, 11 patients with virus-related liver cirrhosis and six patients with obstructive jaundice were enrolled. Significant differences of serum IL-18 levels were observed between patients with Scheuer's stage IV and those with stage I, or II, virus-related liver cirrhosis and obstructive jaundice (P < 0.05). The IL-18 levels in primary biliary cirrhosis increased according to the disease progression, and fell promptly after living-related liver transplantation. Moreover, serum IL-18 levels in primary biliary cirrhosis were correlated with serum bilirubin concentrations and the Risk scores of the Mayo Clinic prognostic model for the disease. The IL-18 levels observed in patients with autoimmune hepatitis were also elevated, and correlated with the activity of the disease. These results indicate that serum interleukin-18 levels reflect the severity of primary biliary cirrhosis, the activity of autoimmune hepatitis, and may be an additive prognostic indicator in primary biliary cirrhosis.

Expression of MAGE, GAGE and BAGE genes in human liver diseases: utility as molecular markers for hepatocellular carcinoma

BACKGROUND/AIMS

The MAGE, GAGE and BAGE genes encode tumor antigens recognized by autologous cytotoxic T lymphocytes. The aim of this study was to evaluate the possibility of using these genes as molecular markers and as the targets of specific immunotherapy for human hepatocellular carcinoma (HCC).

METHODS

The expressions of MAGE-1, MAGE-3, GAGE1-6, GAGE1-2 and BAGE mRNA in 33 surgically resected HCC samples and 26 of their corresponding non-cancerous samples (11 liver cirrhosis and 15 chronic hepatitis) were studied by a reverse-transcription polymerase chain reaction, and were compared with clinicopathological parameters. The expression of MAGE-1 was also examined in 16 biopsied HCC samples.

RESULTS

MAGE-1, MAGE-3, GAGE1-6, GAGE1-2 and BAGE mRNA were expressed in 67%, 39%, 36%, 30%, and 21% of the HCC, respectively. At least one transcript was detected in 88% of the HCC, while no expression was observed in the non-cancerous livers. There was no significant correlation between the expression of any of the tumor antigens examined and the differentiation stage or size of the HCC. Especially, MAGE-1 was highly expressed in small HCC with a diameter of less than 2 cm and in well-differentiated HCC (81% and 70%, respectively), and was also expressed even in alpha-fetoprotein-negative and PIVKA-II-negative HCC (58% and 76%, respectively). The MAGE-1 expression was detected in 69% of biopsied HCC samples and the expression was high in both small and well-differentiated HCC.

CONCLUSIONS

These tumor-specific antigens can be useful as molecular markers and as the possible target molecules for the specific immunotherapy of human HCC.

Expression of telomerase-associated protein 1 and telomerase reverse transcriptase in hepatocellular carcinoma

To know whether two protein components of human telomerase (human telomerase-associated protein 1 (hTEP1) and human telomerase reverse transcriptase (hTERT) are useful markers for telomerase activation in human liver diseases, we examined mRNA levels of these and telomerase activity in human liver samples. Twenty-three human hepatocellular carcinomas (HCCs) and corresponding adjacent livers were analysed for hTEP1 and hTERT expression by semiquantitative reverse transcription-polymerase chain reaction, and for telomerase activity by a telomeric repeat amplification protocol assay. Thirteen liver samples (ten HCCs and three dysplastic nodules) that were biopsied with 21-gauge needles were analysed for hTERT expression. hTEP1 was expressed in all samples examined. No correlation between hTEP1 expression and telomerase activity was observed. hTERT expression significantly correlated with telomerase activity (P< 0.001). The positivity of hTERT for HCC and corresponding non-cancerous liver was 100% and 30.4% respectively (P < 0.001). Seventy-four per cent (17/23) of HCCs showed strong hTERT expression, but none of the non-cancerous liver tissues did. hTERT expression of the 21-gauge needle biopsied specimens showed no significant difference from that of the surgical samples. The present study revealed that hTERT is strongly expressed in most HCCs, and that hTERT but not hTEP1 is a key component regulating telomerase activity in human liver.

Expression of MAGE-1 and -3 genes and gene products in human hepatocellular carcinoma

MAGE gene family encodes peptides recognized by autologous cytotoxic T lymphocytes in a major histocompatibility complex (MHC) class-I restricted fashion. In the present study, we have performed reverse-transcription polymerase chain reaction (RT-PCR) for the genes, as well as immunohistochemical analysis and Western blotting of MAGE-1 and -3 proteins in 33 surgically resected hepatocellular carcinomas (HCCs). MAGE-1 and -3 mRNAs were constitutively expressed exclusively in 78 and 42% of HCCs respectively. On immunohistochemistry with monoclonal antibodies, 77B for MAGE-1 and 57B for MAGE-3, MAGE-1 and -3 proteins were recognized in cytoplasm of only six among 33 (18%) and two of 29 HCCs (7%) respectively. The distribution pattern was mostly focal in HCC nodules. By contrast, the Western blot analysis revealed that the MAGE-1 (46 kDa) and -3 proteins (48 kDa) were expressed in 80 and 60% of 15 HCCs examined respectively. The proteins of MAGE-1 and -3 were also expressed exclusively in HCCs regardless of the histological grading and clinical staging. Our results indicate that the detection of the genes by RT-PCR or the proteins by Western blotting is useful for differentiating early HCCs from non-cancerous lesions, and that the peptides derived from MAGE-1 and -3 proteins might be suitable targets for immunotherapy of human HCC.

Expression of membrane cofactor protein (MCP, CD46) in human liver diseases

Membrane cofactor protein (MCP, CD46) is one of the complement regulatory proteins, and is widely distributed in human organs and protects cells from complement-mediated cytotoxicity. We analysed the distribution and the intensities of MCP in liver diseases and evaluated the role of MCP during hepatocarcinogenesis. Western blot analysis revealed that relative densities (density of the sample/density of the standard sample) of MCP in 27 HCC, 18 liver cirrhosis, nine chronic hepatitis and 12 normal liver were 0.63+/-0.23, 0.21+/-0.07, 0.25+/-0.10 and 0.11+/-0.03 (mean+/-s.d.) respectively. MCP expression in hepatocellular carcinoma (HCC) was significantly higher than that in both liver cirrhosis and chronic hepatitis (P < 0.01). The difference in the tumour sizes, the grades of differentiation and viral marker status did not affect the expression. Immunohistological analysis revealed that MCP was distributed mainly in the basolateral membrane of the hepatic cord in non-cancerous liver, along with endothelial cells and bile duct cells. In HCC, the protein was observed on the membrane in a non-polarized fashion. These data suggest that HCC cells acquire the increased MCP expression in a development of HCC and may escape from tumour-specific complement-mediated cytotoxicity.

Expression of alpha-fetoprotein and albumin genes in human hepatocellular carcinomas: limitations in the application of the genes for targeting human hepatocellular carcinoma in gene therapy

For an approach of gene therapy for hepatocellular carcinoma (HCC), transcriptional regulatory sequence (TRS) of either alpha-fetoprotein (AFP) or albumin has been used for targeting cancer cells. To examine the feasibility of using TRSs of these genes for possible gene therapy of HCCs, the cellular distribution of AFP and albumin gene transcripts was studied in 25 cases of surgically removed human HCCs. AFP gene expression was observed in HCC nodules of 13 cases. The expression in HCC was heterogeneous, and the distribution of the transcripts was mostly sparse and spotty. The higher the serum AFP levels, the larger population of the AFP-expressing HCC cells tended to reflect. In noncancerous liver, a slight AFP expression was found by Northern blot analysis, but the transcripts were not detected in the liver sections. In contrast, albumin expression was found in all HCCs as well as in noncancerous hepatocytes. In HCC, the transcripts for albumin were distributed in cancer cells, and the expression varied with nodules. There were more albumin-expressing cancer cells than the AFP-expressing cells. Albumin expression was retained even in poorly differentiated HCC, although the intensity of the signal was not as strong as in more-differentiated HCCs. Metastatic HCC nodules revealed transcripts for both AFP and albumin genes, and those were clearly recognized in the lung tissue. These results suggest that, for gene therapy for HCCs, neither AFP nor albumin are ideal options for targeting HCC cells. AFP-TRS may be used as a transcriptional regulator in selected cases in which AFP gene expression is observed in the cancer nodules. The serum AFP level appears to be an important indicator in selecting cases. Albumin-TRS in conjunction with retroviral vector might be used in limited cases such as HCCs with no AFP expression. However, careful consideration must be taken, because albumin is constitutively expressed in normal hepatocytes, and AFP-expressing nonmalignant progenitor cells possibly exist.

Proliferating cell nuclear antigen and grade of malignancy in small hepatocellular carcinoma--evaluation in US-guided specimens

BACKGROUND/AIMS

We investigated the value of the proliferating cell nuclear antigen labeling index ratio (PCNA-LI ratio: PCNA-LI of cancer/PCNA-LI of surrounding non-cancerous liver tissue) to clarify the prognosis of the patients bearing small hepatocellular carcinomas (HCC) less than 20 mm in diameter and treated by percutaneous ethanol injection therapy (PEIT).

MATERIAL AND METHODS

Twenty eight HCC patients who had received PEIT were divided into 3 groups. The non-recurrence (NR) group in which no new lesions were observed for at least 18 months after PEIT (13 patients), the early recurrence group (ER) in which lesions recurred within one year (6 patients), and the late recurrence group (LR) in which lesions recurred more than one year after PEIT (9 patients). Immunohistochemical staining of PCNA was done using biopsied specimens.

RESULTS

The PCNA-LI ratio in 37 well differentiated, 13 moderately differentiated, 11 poorly differentiated HCC were 1.86 +/- 0.55, 3.33 +/- 0.51, and 4.75 +/- 0.81 (mean +/- SD), respectively. The ratio in ER group (4.57 +/- 0.57) was significantly higher than that in LR (2.04 +/- 0.61) and NR group (1.87 +/- 0.62) and the PCNA-LI ratio tended to correlate with the periods until the development of recurrent lesions in cases of ER group.

CONCLUSIONS

These results indicate the PCNA-LI ratio, in conjunction with the histological grade, is a useful marker for evaluating the grade of malignancy, and for predicting the period until recurrence after treatment of small HCC.

Cathepsin B in the growth of colorectal cancer: increased activity of cathepsin B in human colorectal cancer

Cathepsin B, a thiol protease, is involved in cancer metastasis. To clarify the role of cathepsin B in tumor progression in human colorectal cancer, the relationship between its activity, immunohistochemical staining, and clinical tumor progression was investigated. Cathepsin B activity in adenocarcinomas was significantly elevated compared with that in the tumor-bearing tissue. Furthermore, the tumor/tumor-bearing tissue (T/Tb) ratio of the activity was significantly higher than that of colorectal adenoma. Immunohistochemical studies demonstrated intense staining in the cancerous tissue. With respect to the clinical stage of tumors, the activity tended to be higher in tumors that had invaded the serosa or subserosa than in those that invaded the proper muscle. The results suggest that cathepsin B participates in the progression of human colorectal cancer, and its increased expression is a sensitive marker of the differentiation between colorectal adenoma and adenocarcinoma.

Cellular distribution of 92-kd type IV collagenase/gelatinase B in human hepatocellular carcinoma

To examine the possible involvement of gelatinase B in human hepatocellular carcinoma (HCC), cellular localization of transcripts and protein of gelatinase B were studied by using in situ hybridization and immunohistochemistry. Transcripts for gelatinase B were observed in tumor cells in 22 cases of 27 HCCs and also in dysplastic nodules. However, there was no significant difference in the expression among histological grades of HCC. The expression was mostly homogeneous, but the intensity varied with the nodules. Of 13 cases with capsular invasion, 12 expressed gelatinase B, whereas 10 of 14 without capsular invasion did (P < 0.05). Gelatinase B transcripts were commonly observed in the sinusoidal cells of the hepatic lobules, in mesenchymal cells both in fibrous capsules and around the necrosis, and also in some undefined cells of the portal tracts of noncancerous liver. Localization of gelatinase B protein was mostly similar to but sometimes different from that of the transcripts in cancer nodules. In conclusion, the expression of gelatinase B appears to be an important characteristic of malignant transformation of hepatocytes. The findings suggest that gelatinase B synthesized by cancer cells plays an important role in the growth and invasion of HCC by degrading surrounding extracellular matrices.

Cathepsin B in the growth of colorectal cancer: suppressive effect of leupeptin on the growth of DMH-induced rat colon neoplasm

Cathepsin B, a thiol protease, has been reported to be involved in cancer progression and metastasis. The suppressive effects of two kinds of protease inhibitors, leupeptin and dietary camostate (FOY-305), on tumorigenesis and progression in 1, 2-dimethylhydrazine (DMH)-induced rat colon neoplasm were examined in relation to tissue cathepsin B activity. Male Donryu rats were treated with leupeptin or FOY-305 during or after the administration of DMH. There were no significant differences in average tumor numbers among all DMH-treated groups. However, the percentage of small tumors was significantly higher in the group in which leupeptin was supplied during DMH administration. This trend was not recognized in the FOY-305-treated groups. The ratio of cathepsin B activity in the tumors to that in the tumor-bearing tissue (T/Tb) was significantly increased with increasing tumor size (P = 0.009). The cathepsin B activity levels in the tumor-bearing mucosa in the groups which received leupeptin or FOY-305 following DMH treatment were both significantly lower than that in the group which received neither protease inhibitor (P = 0.046 and P = 0.0067, respectively). The results obtained indicate that leupeptin may have suppressed tumor growth by lowering the tissue cathepsin B activity.

Telomere length in human liver diseases

To determine the role of telomere-mediated gene stability in hepatocarcinogenesis, we examined the telomere length of human liver with or without chronic liver diseases and hepatocellular carcinomas (HCC). The mean telomere restriction fragment (TRF) length of normal liver (n = 13), chronic hepatitis (n = 11), liver cirrhosis (n = 24) and HCC (n = 24) was 7.8 +/- 0.2, 7.1 +/- 0.3, 6.4 +/- 0.2 and 5.2 +/- 0.2 kb, respectively (mean +/- standard error). TRF length decreased with a progression of chronic liver diseases and that in HCC was significantly shorter than that in other chronic liver diseases (p < 0.05). The ratios of TRF length of HCC to that of corresponding surrounding liver of well differentiated (n = 7), moderately differentiated (n = 10) and poorly differentiated (n = 4) HCCs were 0.83 +/- 0.06, 0.75 +/- 0.05 and 0.98 +/- 0.09, respectively. The ratio of poorly differentiated HCC was significantly higher than that of moderately differentiated HCC (p < 0.05). A comparison between the size and telomere length ratio of moderately differentiated HCCs revealed a decrease of the ratio with size until it reached 50 mm in diameter. In contrast, the ratio increased as the size enlarged over 50 mm. These findings suggest that the gene stability of the liver cells mediated by the telomere is reduced as chronic liver disease progresses and that telomerase is activated in poorly differentiated HCC and moderately differentiated HCC over 50 mm in diameter.

Usefulness of indocyanine green injection during ultrasound-guided liver biopsy for the diagnosis of small hepatocellular carcinoma

To diagnose hepatocellular carcinoma (HCC) functionally and immediately, we examined the usefulness of indocyanine green (ICG) injection during ultrasound-guided liver biopsy. Liver specimens were obtained after intravenous ICG injection by ultrasound-guided biopsy from 251 space-occupying lesions (SOL) in 136 patients. The tissues were immediately examined for ICG uptake using an infrared Vidicon camera and were also subjected to histopathological examinations. Of the 112 ICG-negative biopsy specimens, 105 were histologically diagnosed as HCC, 6 as dysplastic nodules (DN) and 1 as a regenerative nodule (RN). Of the 139 ICG-positive specimens, 18 were diagnosed as HCC, 1 as DN and 120 as RN. The sensitivity of the absence of ICG uptake (SEAIU), the specificity of the absence of ICG uptake (SPAIU), and the positive predictive value of the absence of ICG uptake (PPAIU) for the diagnosis of HCC were 85.3%, 94.5% and 93.8%, respectively. Of the 251 SOLs, 184 were less than 2 cm. SEAIU, SPAIU and PPAIU for the diagnosis of these small HCC were 85.3%, 94.5% and 91.4%, respectively. These results support the reliability of ICG injection during ultrasound-guided liver biopsy to diagnose even small HCC.