Natural killer T cells from interleukin-4-deficient mice are defective in early interferon-gamma production in response to alpha-galactosylceramide

Discovery of the natural killer (NK) T cell-specific ligand, alpha-galactosylceramide (alpha-GalCer) has enabled us to investigate the functional regulation of NKT cells. However, the detailed mechanism of cytokine production by NKT cells remains to be elucidated. Here we evaluated the role of interleukin (IL)-4 in the production of interferon (IFN)-gamma from NKT cells using IL-4-deficient C57BL/6 mice (IL-4(-/-) mice). Administration of alpha-GalCer into wild-type C57BL/6 mice caused the production of both IFN-gamma and IL-4 in serum or cytoplasm within 4 h of the injection. Unexpectedly, however, IL-4(-/-) mice-derived NKT cells did not produce any IFN-gamma at early phase after primary stimulation with alpha-GalCer. Because NKT cells from IL-4(-/-) mice produced IFN-gamma when they were stimulated secondarily with alpha-GalCer in vitro for 72 h, NKT cells from IL-4(-/-) mice were not completely genetically deficient for IFN-gamma production. To elucidate which cells, NKT cells or dendritic cells (DC), were responsible for the deficiency in IFN-gamma production in IL-4(-/-) mice, we carried out an add-back experiment using purified NKT cells and DC, which were prepared from either wild-type mice or IL-4(-/-) mice. NKT cells from wild-type mice produced IFN-gamma when they were cocultured with DC prepared from either wild-type or IL-4(-/-) mice, whereas NKT cells from IL-4(-/-) mice did not produce IFN-gamma by coculturing with DC from either wild-type or IL-4(-/-) mice. These results indicate that NKT cells, not DC, were responsible for the deficiency in IFN-gamma production in IL-4(-/-) mice. Thus, IL-4 is required for the activation of NKT cells to produce IFN-gamma in response to alpha-GalCer.

AsialoGM1+CD8+ central memory-type T cells in unimmunized mice as novel immunomodulator of IFN- -dependent type 1 immunity

In unimmunized specific pathogen-free mice, there are unique memory-type CD8(+) T cell populations expressing asialoGM1 (ASGM1). These cells were classified into central memory-type T cells (T(CMT)) judging from their expression profile of CD44, IL-2Rbeta, CD62L and CCR7 cell-surface molecules. Among CD44(high)CD8(+) so-called memory CD8(+) T cell population, ASGM1(+)CD44(high)CD8(+) T(CMT), but not ASGM1(-)CD44(high)CD8(+) memory T cells, produced IFN-gamma by stimulation with anti-CD3 mAb. The physiological significance of ASGM1(+)CD8(+) T(CMT) as early source of IFN-gamma was also demonstrated in vivo. Namely, intravenous injection of anti-CD3 mAb (2 microg) resulted in early activation of IFN-gamma-producing ASGM1(+)CD8(+) T(CMT) cells as well as NKT and NK cells. Unexpectedly, however, few IFN-gamma-producing CD4(+) T cells were detected until 4 h after anti-CD3 mAb administration. Thus, ASGM1(+)CD8(+) T(CMT) were demonstrated to be early IFN-gamma producer, which may be crucial for T(h)1-dependent cellular immunity. Indeed, co-culture of naive CD4(+) T cells with ASGM1(+)CD8(+) T(CMT) but not ASGM1(-)CD8(+) T cells caused a great acceleration of IFN-gamma-producing T(h)1 cells in vitro. Finally, we found that T(h)1-prone C57BL/6 mice possessed higher percentage (10%) of ASGM1(+)CD8(+) T(CMT) in CD8(+) T cells compared with that (3%) of T(h)2-prone BALB/c mice. Moreover, ASGM1(+)CD8(+) T(CMT) derived from C57BL/6 mice produced higher levels of IFN-gamma compared with those from BALB/c mice. Thus, ASGM1(+)CD8(+) T(CMT), whose differentiation in vivo is genetically controlled, appear to play a critical role in the control of type 1 immunity, which is essential for therapy of tumors and infectious diseases.

Interleukin-12-responding asialoGM1+CD8+ central memory-type T cells as precursor cells for interferon-gamma-producing killer T cells

While investigating CD8(+) memory T cells in unimmunized C57BL/6 mice, we found that there were unique memory-type CD8(+) T cells expressing asialoGM1 (ASGM1), CD62L and CCR7 cell surface molecules, which occupied approximately 10% of CD8(+) T cells and 35% of CD44(+) memory CD8(+) T cells. Culture of freshly isolated ASGM1(+)CD8(+) T cells with interleukin (IL)-12 plus IL-2 caused the proliferation and generation of killer T cells. Moreover, ASGM1(+)CD8(+) T cells, but not ASGM1(-)CD8(+) T cells, produced high levels of interferon (IFN)-gamma in response to IL-12 plus IL-2. Although ASGM1(+)CD8(+) T cells showed no significant responses to IL-12 alone or IL-2 alone, pulse incubation of ASGM1(+)CD8(+) T cells with IL-12 at an earlier time (0-12 h), and subsequently with IL-2 at a later time (12-24 h), caused the same levels of proliferation, killer cell generation and IFN-gamma production as when they were incubated simultaneously with IL-12 plus IL-2 for 24 h. Thus, ASGM1(+)CD8(+) T cells appeared to respond to IL-12 directly to acquire IL-2 responsiveness and differentiate into IFN-gamma-producing killer T cells. Indeed, freshly isolated ASGM1(+)CD8(+) T cells, but not ASGM1(-)CD8(+) T cells, expressed higher levels of IL-12R beta2 mRNA. The fact that IL-12 administration in vivo caused the generation of ASGM1(+)CD8(+) killer T cells in an IFN-gamma-dependent manner further indicated a physiological significance of ASGM1(+)CD8(+) central memory-type T cells in IL-12-induced immunoregulation for the therapy of tumors and infectious diseases.

Transgenic rescue from embryonic lethality and renal carcinogenesis in the Nihon rat model by introduction of a wild-type Bhd gene

We recently reported that a germline insertion of a single nucleotide in the rat homologue of the human Birt-Hogg-Dubé gene (BHD) gives rise to dominantly inherited cancer in the Nihon rat model. In this study, we constructed transgenic Nihon rats with introduction of a wild-type Bhd gene to ascertain whether suppression of the Nihon phenotype is possible. Rescue from embryonic lethality of mutant homozygotes (Nihon/Nihon) and suppression of renal carcinogenesis in heterozygotes (Nihon/+) were both observed, defining the germline Bhd mutation in the Nihon rat as an embryonal lethal and tumor predisposing mutation. This transgenic rescue system will be useful to analyse Bhd gene function, its relation to tumorigenesis in vivo, and genetic-environmental interactions in carcinogenesis.

Development of a functional cDNA array for evaluation of the Th1/Th2 balance

The immune balance controlled by CD4(+) helper T cell subsets (T helper 1 (Th1) and T helper 2 (Th2)) is crucial for immunoregulation and its imbalance causes various immune diseases including infections, allergic disorders and autoimmune diseases. Therefore, it is of great importance to develop a system of diagnosing Th1/Th2 imbalances for curing immune diseases. Here we developed a functional cDNA array filter useful for assessing the Th1/Th2 balance in mice. To overcome the disadvantages of conventional microarrays carrying thousands of genes, we prepared an array filter containing 40 Th1-specific and 32 Th2-specific genes, which were selected from over 8700 genes based on (i) the specificity of expression in Th1 or Th2 cells and (ii) an expression level which is high enough for detection using a DNA array. This array filter provided a prompt and precise evaluation for the skewing of the Th1/Th2 balance combined with our calculation algorithm. The bias toward Th1 or Th2 was evaluated visually at a glance by aligning the genes on the filter. Moreover, we succeeded in evaluating the skewing of the Th1/Th2 balance in vivo during acute graft versus host disease (GVHD). Thus, this array filter will provide a novel tool for evaluation of the Th1/Th2 balance in a variety of immune diseases.

[Development of DNA array filter useful for the analysis of Th1/Th2 balance]

DNA arrays are useful for determining the expression levels of a number of genes at once. We utilized this technique to evaluate the Th1/Th2 balance in vivo. Immune responses are controlled by two types of helper T cells, Th1 and Th2. Once the balance of Th1/Th2 immunity is disrupted, various immune diseases can develop. Thus, it is important to evaluate the Th1/Th2 balance in each patient for diagnosis, treatment and/or prophylaxis of immune diseases. We have identified a number of genes specifically expressed in Th1 or Th2 cells, and developed a DNA array filter spotted with these genes. We confirmed that this filter is useful for the evaluation of changes in the immune balance in vivo. Clinical application of this technology may lead to the tailor-made therapy of immune diseases through the evaluation of the immune balance in each patient.

NKT cells act as regulatory cells rather than killer cells during activation of NK cell-mediated cytotoxicity by alpha-galactosylceramide in vivo

Administration of NKT cell ligands, alpha-galactosylceramide (alpha-GalCer) resulted in the activation of both cytokine production and natural killing. These responses were abolished in both CD1d-deficient mice and Valpha14NKT-deficient mice. Therefore, NKT cells have been considered to be responsible cells for both cytokine production and natural killing. Here, we reevaluated a critical role of NKT and NK cells at early time after alpha-GalCer administration. Intracellular staining experiments demonstrated that NKT cells were the earliest source of both IL-4 and IFN-gamma production after alpha-GalCer administration in vivo. However, these alpha-GalCer-activated NKT cells exhibited no significant natural killing activity. In contrast, isolated NK1.1+CD3- classical NK cells exhibited greatly enhanced natural killing activity 6 h after alpha-GalCer administration. NKT cells, however, exhibited a strong cytotoxicity when they were activated and expanded with alpha-GalCer plus IL-2 in vitro. These results indicated that NKT cells act as regulatory cells via production of cytokines for activation of NK cell-mediated cytotoxicity in vivo at early phase after alpha-GalCer administration. Thus, NK cells rather than NKT cells may be a crucial early activated killer induced by alpha-GalCer in vivo.

Unexpected role of TNF-alpha in graft versus host reaction (GVHR): donor-derived TNF-alpha suppresses GVHR via inhibition of IFN-gamma-dependent donor type-1 immunity

Graft versus host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation, leading to significant morbidity and mortality. Host-derived TNF-alpha play a role in the induction of allo-reactive donor T cell activation and the pathogenesis of GVHD. On the other hand, the precise role of donor-derived TNF-alpha in GVHD remains unclear. To elucidate this issue, we designed an acute GVHD model using (B6 x D2) F1 recipient mice transferred with spleen cells derived from either wild-type or TNF-alpha(-/-) C57BL/6 mice. Surprisingly, we found that spleen cells from TNF-alpha(-/-) mice induce more severe graft versus host reaction (GVHR) than wild-type spleen cells upon transfer into B6D2F1 mice. Transplantation of TNF-alpha(-/-) mouse spleen cells was associated with enhanced anti-host CTL generation and augmented deletion of host cells. Moreover, mice receiving TNF-alpha(-/-) cells showed significantly higher levels of serum IFN-gamma, which was mainly produced by donor CD8+ T cells. We also demonstrated that TNF-alpha deficiency in donor spleen cells caused a marked elevation of TNF-alpha producing capacity by LPS-stimulated host macrophages. Such enhanced GVHR was completely prevented by using TNF-alpha(-/-)IFN-gamma(-/-) splenic cells. Our findings demonstrate, for the first time, that donor-derived TNF-alpha suppress GVHR by inhibiting IFN-gamma-dependent donor type-1 immunity which is essential for host TNF-alpha elevation.

Generation of leukemia-specific T-helper type 1 cells applicable to human leukemia cell-therapy

Leukemic dendritic cells (DC) were induced from the peripheral blood (PB) or bone marrow (BM) of leukemia patients by culture with (i) GM-CSF + IL-3 (neutral condition); (ii) GM-CSF + IL-3 + IL-12 + IFN-gamma (type 1-condition); or (iii) GM-CSF + IL-3 + IL-4 (type 2-condition). Although leukemic cells rapidly differentiated into adhesive leukemic DC in all culture conditions, type1-conditions were the most suitable for inducing leukemic DC expressing high levels of HLA and costimulatory molecules. Addition of IL-2 after 2 days of culture induced a preferential growth of minor T cell populations interacting with leukemic DC. In particular, IFN-gamma-producing CD4+ Th1 cells were efficiently expanded in type 1 culture conditions but nor in neutral or type 2-conditions. However, CD4+ T cells expanded in neutral conditions showed Th1-like functions if they were pulsed with IFN-gamma for 2 days before harvest. Such Th1 cells produced IFN-gamma and exhibited cytotoxicity in response to autologous leukemia cells. We further demonstrated that IFN-gamma production of leukemia-specific Th1 cells was blocked by anti-HLA-DR mAb. Thus, we established a novel culture system for inducing leukemia-specific Th1 cells.

Potentiation of Tumor Eradication by Adoptive Immunotherapy with T-cell Receptor Gene-Transduced T-Helper Type 1 Cells

Adoptive immunotherapy using antigen-specific T-helper type 1 (Th1) cells has been considered as a potential strategy for tumor immunotherapy. However, its application to tumor immunotherapy has been hampered by difficulties in expanding tumor-specific Th1 cells from tumor-bearing hosts. Here, we have developed an efficient protocol for preparing mouse antigen-specific Th1 cells from nonspecifically activated Th cells after retroviral transfer of T-cell receptor (TCR)-alpha and TCR-beta genes. We demonstrate that Th1 cells transduced with the TCR-alpha and -beta genes from the I-A(d)-restricted ovalbumin (OVA)(323-339)-specific T-cell clone DO11.10 produce IFN-gamma but not interleukin-4 in response to stimulation with OVA(323-339) peptides or A20 B lymphoma (A20-OVA) cells expressing OVA as a model tumor antigen. TCR-transduced Th1 cells also exhibited cytotoxicity against tumor cells in an antigen-specific manner. Moreover, adoptive transfer of TCR-transduced Th1 cells, but not mock-transduced Th1 cells, exhibited potent antitumor activity in vivo and, when combined with cyclophosphamide treatment, completely eradicated established tumor masses. Thus, TCR-transduced Th1 cells are a promising alternative for the development of effective adoptive immunotherapies.

Critical role of the Th1/Tc1 circuit for the generation of tumor-specific CTL during tumor eradication in vivo by Th1-cell therapy

Th1 and Th2 cells obtained from OVA-specific T cell receptor transgenic mice completely eradicated the tumor mass when transferred into mice bearing A20-OVA tumor cells expressing OVA as a model tumor antigen. To elucidate the role of Tc1 or Tc2 cells during tumor eradication by Th1- or Th2-cell therapy, spleen cells obtained from mice cured of tumor by the therapy were re-stimulated with the model tumor antigen (OVA) for 4 days. Spleen cells obtained from mice cured by Th1-cell therapy produced high levels of IFN-gamma, while spleen cells from mice cured by Th2-cell therapy produced high levels of IL-4. Intracellular staining analysis demonstrated that a high frequency of IFN-gamma-producing Tc1 cells was induced in mice given Th1-cell therapy. In contrast, IL-4-producing Tc2 cells were mainly induced in mice after Th2-cell therapy. Moreover, Tc1, but not Tc2, exhibited a tumor-specific cytotoxicity against A20-OVA but not against CMS-7 fibrosarcoma. Thus, immunological memory essential for CTL generation was induced by the Th1/Tc1 circuit, but not by the Th2/Tc2 circuit. We also demonstrated that Th1-cell therapy is greatly augmented by combination therapy with cyclophosphamide treatment. This finding indicated that adoptive chemoimmunotherapy using Th1 cells should be applicable as a novel tool to enhance the Th1/Tc1 circuit, which is beneficial for inducing tumor eradication in vivo.

Differential regulation of VLA-2 expression on Th1 and Th2 cells: a novel marker for the classification of Th subsets

We found that T(h)1 cells derived from ovalbumin (OVA)-specific TCR transgenic (DO11.10) mice showed significantly higher levels of VLA-2 (CD49b/CD29) expression than T(h)2 cells. In the early days (until 6 days) during induction of T(h)1 or T(h)2 cells, the expression of VLA-2 was gradually increased on both T(h) subsets. Thereafter, VLA-2 expression was further up-regulated on T(h)1 cells until 13 days, while a significant decrease of VLA-2 was observed in T(h)2 cells, resulting in a marked difference of expression at day 13. Up-regulation of VLA-2 on T(h)1 cells was not impaired in IFN-gamma(-/-) T(h) cells nor blocked by anti-IL-12 mAb treatment on wild-type T(h) cells, suggesting that up-regulation of VLA-2 on T(h)1 cells occurs in an IFN-gamma- and IL-12-independent manner. In contrast, T(h) cells cultured under IL-4-depleted T(h)2 conditions abrogated the down-regulation of VLA-2 expression, suggesting that down-regulation of VLA-2 expression on T(h)2 cells was dependent on IL-4. The finding that STAT6(-/-) T(h)2 cells did not show any down-regulation of VLA-2 expression and expressed the same levels of VLA-2 as T(h)1 cells indicated a critical role for the IL-4 receptor/STAT6 signaling pathway in IL-4-dependent down-regulation of VLA-2 on T(h)2 cells. Stimulation of T(h)1 cells by VLA-2 ligands such as collagen type I or agonistic mAb provided co-stimulation for anti-CD3 mAb-induced IFN-gamma production. However, these ligations had little effect on the IL-4 production of T(h)2 cells. Together, these results indicate that VLA-2 is a novel functional marker that dissociates T(h)1 from T(h)2 cells, and thus might be useful for therapeutic monitoring of T(h)1-dependent immune diseases such as rheumatoid arthritis or Crohn's disease.

An efficient method to prepare T cell receptor gene-transduced cytotoxic T lymphocytes type 1 applicable to tumor gene cell-therapy

Genes encoding 2C T cell receptor (TCR) alpha, beta chains from H-2(b)-restricted L(d)-specific CD8(+) cells were successfully transduced into polyclonally activated CD8(+) cells by retroviral modification to generate antigen-specific cytotoxic T lymphocytes (CTL). Antigen-nonspecific CD8(+) T cells polyclonally expanded in the presence of interleukin (IL)-2, Th1 cytokines (interferon (IFN)-gamma and IL-12) and anti-IL-4 monoclonal antibody showed neither cytokine production nor cytotoxicity in response to L(d)-expressing P815 tumor cells. However, 2C-TCR gene-modified CD8(+) T cells exhibited both IFN-gamma production and cytotoxicity in response to P815 tumor cells. The antitumor activity of TCR gene-modified Tc1 cells was also demonstrated in vivo by Winn's assay. Thus, we have developed an efficient method to induce TCR gene-modified antigen-specific Tc1 cells that exhibit antitumor activity both in vitro and in vivo.

[Genetically engineered mice and its application to bioindustry]

More than 2 decades have past since the first transgenic mouse was created. In this review we will focus on recent technologies in the field of mouse genetic engineering and on its application to bioindustry. The most important milestone in this field was the invention of the gene targeting technique. Recent improvement of this technique to conditional gene targeting together with the Cre/IoxP system further encouraged the generation of mutant mice. It is obvious that there will be a great demand for some mutant mice as experimental models of human disease or as resources of experimental material for basis biological research. Thus, creation of such mice would be a rewarding challenge for a biological enterprise.

Th1 cytokine-conditioned bone marrow-derived dendritic cells can bypass the requirement for Th functions during the generation of CD8+ CTL

Bone marrow-derived dendritic cell (BMDC) subsets have distinct immunoregulatory functions. Th1 cytokine-induced BMDC (BMDC1), compared with Th2 cytokine-induced BMDC2, have superior activities for the differentiation and expansion of CTL. To evaluate the cellular interactions between dendritic cells and CD8+ T cells for the induction of CTL, BALB/c-derived BMDC subsets were cocultured with purified CD8+ T cells from C57BL/6 mice. Our results demonstrate that BMDC1 support the generation of allogeneic CD8+ CTL in the absence of CD4+ Th cells. In contrast, BMDC0 (GM-CSF- plus IL-3-induced BMDC) and BMDC2 failed to promote the differentiation of CD8+ CTL. Using Ab-blocking experiments and studies with gene knockout mice, IL-2 and LFA-1 are demonstrated to be critical for BMDC1-induced CTL differentiation. Unexpectedly, BMDC1 were able to induce CTL from CD8+ T cells isolated from IFN-gamma-/- and IFN-gamma receptor-/- mice. However, BMDC1 produced higher levels of IFN-beta than other BMDC subsets, and anti-IFN-beta mAb blocked BMDC1-dependent CTL generation. These results indicated an indispensable role of IFN-beta, but not IFN-gamma, during BMDC1-induced CTL differentiation. We conclude that Th1-cytokine-conditioned BMDC1 can bypass Th cell function for the differentiation of naive CD8+ T cells into CTL.

Analysis of a uranium solution for evaluating the total number of fissions in the JCO criticality accident in Tokai-mura

The uranium solution in the precipitation tank in the JCO's uranium conversion facility was analyzed in order to evaluate the total number of fissions in the criticality accident. Two analytical groups at JAERI performed chemical analyses independently in order to check the validity of the results: the concentration of the fission products (95Zr, 99Mo, 103Ru, 131I, 140Ba, etc), uranium, boron and impurity elements in the solution. The analytical results obtained by the two groups were almost in agreement within the analytical error. The number of fissions per one gram of uranium in the accident was determined to be (1.5 +/- 0.1 ) x 10(14). Also, the total number of events was evaluated to be (2.5 +/- 0.1) x 10(18) fissions using the total amount of uranium (16.6 kg) fed into the precipitation tank at the accident.

A critical role for mouse CXC chemokine(s) in pulmonary neutrophilia during Th type 1-dependent airway inflammation

Ag-specific Th1 and Th2 cells have been demonstrated to play a critical role in the induction of allergic diseases. Here we have investigated the precise mechanisms of Th1-induced airway inflammation. Airway inflammation was induced in BALB/c mice by transfer of freshly induced OVA-specific Th1 or Th2 cells followed by OVA inhalation. In this model, both Th1 and Th2 cells induced airway inflammation. The former induced neutrophilia in airways, whereas the latter induced eosinophilia. Moreover, we found that Th1 cells induced more severe airway hyperresponsiveness (AHR) than Th2 cells. The eosinophilia induced by Th2 cell infusion was almost completely blocked by administration of anti-IL-5 mAb, but not anti-IL-4 mAb. In contrast, Th1-induced AHR and pulmonary neutrophilia were inhibited by the administration of anti-human IL-8R Ab, which blocks the function of mouse CXC chemokine(s). These findings reveal a critical role of mouse CXC chemokine(s) in Th1-dependent pulmonary neutrophilia and AHR.

Transitions induced by the discreteness of molecules in a small autocatalytic system

The autocatalytic reaction system with a small number of molecules is studied numerically by stochastic particle simulations. A novel state due to fluctuation and discreteness in molecular numbers is found, characterized as an extinction of molecule species alternately in the autocatalytic reaction loop. Phase transition to this state with changes of the system size and flow is studied, while a single-molecule switch of the molecule distributions is reported. The relevance of the results to intracellular processes is briefly discussed.

Analysis of the expression of intercellular adhesion molecule-1 in cells of the human bronchial epithelial cell line NCI-H292

The mechanism of the expression of intercellular adhesion molecule-1 (ICAM-1) on epithelial cells was analyzed using NCI-H292 cells, a human bronchial epithelial cell line. Treatment with interferon-gamma (100 U/ml) or the protein kinase C activator 12-O-tetradecanoylphorbol 13-acetate (TPA) (16.2 nM) induced ICAM-1 expression. The interferon-gamma-induced ICAM-1 expression was reduced by the tyrosine kinase inhibitor genistein (4',5,7-trihydroxyisoflavone) (37 to 185 microM), but not by the protein kinase C inhibitor Ro 31-8425 ((3-[8-(aminomethyl)-6,7,8,9-tetrahydropyrido [1.2-a]indol-10-yl]-4-(1-methyl-1 H-pyrrole-2,3-dione) (10 microM). The TPA-induced ICAM-1 expression was reduced by the protein kinase C inhibitor Ro 31-8425 (1 to 10 microM), but not by the tyrosine kinase inhibitor genistein (185 microM). The protein kinase A inhibitor H-89 (N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide) did not affect the ICAM-1 expression induced by interferon-gamma or TPA. Pyrrolidine dithiocarbamate (1-pyrrolidinecarbodithioic acid) (100 microM), an inhibitor of nuclear factor kappaB (NF-kappaB) activation. enhanced the ICAM-1 expression induced by interferon-y, but reduced that induced by TPA. The changes in ICAM-1 expression on the cell surface were correlated with the changes in ICAM-1 mRNA levels. Combined treatment with interferon-gamma and TPA induced more than additive ICAM-1 expression. These findings suggest that interferon-gamma induces ICAM-1 expression by a tyrosine kinase-dependent mechanism, but that TPA induces it by a protein kinase C- and NF-kappaB-dependent mechanism.

Relevance of irinotecan hydrochloride-induced diarrhea to the level of prostaglandin E2 and water absorption of large intestine in rats

For characterization of the mechanism(s) of severe diarrhea due to the anticancer agent, irinotecan hydrochloride (CPT-11), examination was made of the relation of CPT-11-related diarrhea to colonic prostaglandin E2 (PGE2) and water absorption in rats. Acute diarrheal symptoms were observed within 1 hr after the administration of CPT-11 to rats, with increased PGE2 and decreased water absorption in the colon. Treatment with atropine at 1 mg/kg, s.c. was noted to inhibit intestinal PGE2 and the CPT-11-related acute diarrheal symptoms, indicating that these diarrheal symptoms were mediated through the cholinergic nervous system accelerated functionally by CPT-11. On the other hand, daily treatment of CPT-11 at the same dose resulted in chronic diarrheal symptoms in all animals 3 days after CPT-11 treatment. Histopathological changes observed in the descending colon and ileum of the rats included degeneration and necrosis of villi and cryptal cells and a decrease in the number of the goblet cells. Significantly increased PGE2 and impaired water absorption of the descending colon were also observed during the chronic diarrheal stage. It can be considered that the chronic diarrheal symptoms appear as a consequence of the gastrointestinal injury characterized by significant increase in PGE2 accompanied by impaired water absorption.

Transforming growth factor beta 1 (TGF-beta 1) produced in tumour tissue after chemotherapy acts as a lymphokine-activated killer attractant

Using an under agarose migration (UAM) assay, we studied lymphokine-activated killer (LAK)-attractant activity in cultured conditioned medium of tumour tissues after chemotherapy as a possible mechanism of enhanced LAK cell accumulation into tumour tissues after chemotherapy. BMT-11 is a fibrosarcoma developed in C57BL/6 mice. The conditioned medium of BMT-11 tumour tissues obtained from mice treated with various anti-cancer drugs had chemotactic activity for LAK cells (LAK-attractant activity). mRNA expression of interleukin (IL)-1 alpha, IL-6, IL-8, interferon (IFN)-gamma, and tumour necrosis factor (TNF)-alpha was observed in untreated tumour tissues, which were not enhanced by cyclophosphamide treatment. mRNA expression of TGF-beta 1 was not detected in untreated tumour tissues by reverse transcription-polymerase chain reaction (RT-PCR), but was detected in tumour tissues treated with cyclophosphamide. Recombinant human TGF-beta 1 showed LAK-attractant activity at a concentration of 0.1 ng ml-1 and 1 ng ml-1, whereas fresh splenocytes were not attracted by TGF-beta 1. Anti-TGF-beta 1 antibody inhibited LAK-attractant activity in the conditioned medium of tumour tissues treated with cyclophosphamide to approximately 35% that of control at 100 micrograms ml-1. These findings indicate that TGF-beta 1 produced in the tumour tissues of mice treated with anti-cancer drugs could be a LAK attractant. By a 4 h 51Cr release assay of natural killer cell-resistant BMT-11 tumour cells, we observed that TGF-beta 1 at a concentration from 0.01 ng ml-1 to 10 ng ml-1 did not inhibit LAK activity in an effector phase. Taken together, we suggest that TGF-beta 1 produced in tumour tissues after chemotherapy participates in gathering transferred LAK cells and contributes to the therapeutic effects of transferred LAK cells.

Histochemical demonstration of copper in LEC rat liver

Livers of LEC rats were histochemically stained for copper according to the modified Timm's method, which includes trichloroacetic acid (TCA) treatment. TCA pretreatment was effective in removing zinc and iron, leaving as the major metal in the liver. Hepatocytes in 3-month-old rats were stained intensely by the modified Timm's method, both in frozen sections and in paraffin-embedded specimens. The centrilobular hepatocytes were usually stained, but positive cells were also randomly distributed in the hepatic lobes, showing a mosaic pattern. The staining was intensified in 8- compared to 3-month-old LEC rats. In contrast hepatocytes from LEA rats, the normal counterpart of LEC rats, were faintly stained for copper. Proliferating cholangioles found in older LEC rats were shown to lack copper deposition, and hepatocellular carcinoma showed less copper deposits than the hepatocytes surrounding the tumor. The copper staining was augmented in livers of LEC rats subjected to copper-loading, but was less intense in the livers treated with D-penicillamine. The staining intensity under the various experimental conditions showed good correlation with the copper concentration. Lysosomal deposition of copper in hepatocytes was demonstrated by electron microscopic analysis for copper. Thus the modified Timm's method was shown to produce valuable results in demonstrating copper in LEC rat livers, providing important information for an understanding of the mechanism of copper deposition and hepatic disease of the animal.

Prevention of spontaneous hepatocellular carcinoma in Long-Evans cinnamon rats with hereditary hepatitis by the administration of D-penicillamine

Acute hepatitis spontaneously develops in the Long-Evans Cinnamon rat at the age of 4 mo, and eventually hepatocellular carcinoma develops after the chronic hepatitis that persists for over a year. Previously, abnormal copper accumulation was found in the livers of Long-Evans Cinnamon rats from birth, and it was reported that short-term administration of D-penicillamine, a copper-chelating agent, prevented acute hepatitis in Long-Evans Cinnamon rats. In this study we investigated whether long-term administration of D-penicillamine could also prevent chronic hepatitis and subsequent hepatocellular carcinoma in Long-Evans Cinnamon rats. During long-term observation, which was continued from 11 to 70 wk after birth, no elevation of serum transaminase levels was observed in the Long-Evans Cinnamon rats treated with D-penicillamine. Moreover, no histological changes characteristic of the chronic hepatitis were observed in D-penicillamine-treated Long-Evans Cinnamon rats, which were killed at 70 wk of age. Furthermore, placental glutathione S-transferase-positive foci, described as a marker for preneoplastic lesions in the liver, were not detected, and thus hepatocarcinogenesis was completely prevented in D-penicillamine-treated Long-Evans Cinnamon rats. We also found that the amount of 8-hydroxy-deoxyguanosine, one of oxidative DNA damage products in the liver, was decreased in the Long-Evans Cinnamon rats treated with D-penicillamine. These findings suggest that a process of the prolonged liver-cell injury and regeneration was essential for spontaneous development of hepatocellular carcinoma in Long-Evans Cinnamon rats with abnormal copper metabolism.

Elevated level of 8-hydroxydeoxyguanosine in DNA of liver, kidneys, and brain of Long-Evans Cinnamon rats

Long-Evans Cinnamon (LEC) rats, a mutant strain originating from Long-Evans rats, spontaneously develop hereditary hepatitis followed by hepatocellular carcinoma. The hepatic disorder in LEC rats is associated with their abnormal copper metabolism; metal-catalyzed reactions often give rise to oxygen radicals, which may be related to the carcinogenesis. By means of high-pressure liquid chromatography with electrochemical detection, cellular DNA damage caused by oxygen radicals can be assessed in terms of the amount of 8-hydroxydeoxyguanosine (oh8dG). We assayed the amount of oh8dG in DNA of liver, kidneys, and brain of LEC and Long-Evans Agouti (LEA) control rats in seven groups (n = 3 to 6) aged from 5 weeks to 24 months. Control rats, a healthy sibling line, were age-matched. The amount of oh8dG was correlated with the severity of the age-related clinical symptoms in LEC rats. The amount was higher in LEC rats than in the controls, especially in the liver at the acute stage of hepatitis. These findings suggest that oxygen radicals may be important in the carcinogenesis that occurs in LEC rats.

Augmented accumulation of transferred lymphokine-activated killer (LAK) cells at murine tumor sites through production of LAK-attractant facilitated by chemotherapy

We observed that effects of adoptive immunotherapy with lymphokine-activated killer (LAK) cells on BMT-11, a fibrosarcoma in C57BL/6 mice were improved by combination with cyclophosphamide (CY)-chemotherapy corresponding to enhanced accumulation at tumor sites of LAK cells. On the other hand, cytotoxic T lymphocytes (CTLs) which were able to accumulate at tumor sites more densely than LAK cells produced significant therapeutic effects by themselves. We have also found observed that LAK-attractant activity was detected in conditioned medium (CM) of CY-treated tumor tissue but not in the CM of untreated tumor tissue. These findings reveal that CY-chemotherapy facilitates LAK-attractant-production and enhances the accumulation in tumor tissue of LAK cells and that therapeutic effects of adoptive transfer of LAK cells are augmented by cancer chemotherapy through the enhanced accumulation of LAK cells.