Sendai virus fusion protein mediates simultaneous induction of MHC class I/II-dependent mucosal and systemic immune responses via the nasopharyngeal-associated lymphoreticular tissue immune system

Nasal administration of Ags using a novel hybrid Ag delivery vehicle composed of envelope glycoproteins of Sendai virus on the surface of liposome membranes (fusogenic liposome) efficiently delivered Ags to Ag-sampling M cells in nasopharyngeal-associated lymphoreticular tissue. Additionally, fusogenic liposomes also effectively delivered the Ags into epithelial cells and macrophages in nasopharyngeal-associated lymphoreticular tissue and nasal passages. In vitro Ag presentation assays clearly showed that fusogenic liposomes effectively presented encapsulated Ags via the MHC class II-dependent pathway of epithelial cells as well as macrophages. Fusogenic liposomes also have an adjuvant activity against mucosal epithelial cells to enhance MHC class II expression. According to these high delivery and adjuvant activities of fusogenic liposomes, nasal immunization with OVA-encapsulated fusogenic liposomes induced high levels of OVA-specific CD4(+) Th1 and Th2 cell responses. Furthermore, Ag-specific CTL responses and Ab productions were also elicited at both mucosal and systemic sites by nasal immunization with Ag-encapsulated fusogenic liposomes. These results indicate that fusogenic liposome is a versatile and effective system for the stimulation of Ag-specific immune responses at both mucosal and systemic compartments.

Increased sensitivity to vecuronium and prolonged duration of its action in patients with end-stage renal failure

STUDY OBJECTIVES

To determine whether the duration of action of vecuronium is influenced by chronic renal failure.

DESIGN

Prospective clinical comparison.

SETTING

Operating room, Hokkaido University Hospital.

PATIENTS

7 adult ASA physical status II and III patients with impaired renal function undergoing living-related renal transplantation (Group A), 5 adult ASA physical status II and III patients with impaired renal function undergoing elective surgery other than renal transplantation (Group B), and 13 adult ASA physical status I and II patients with normal hepatorenal function undergoing elective surgery (Group C).

INTERVENTIONS

Anesthesia was induced with thiamylal 5 mg x kg(-1) and fentanyl 100 microg IV and maintained with 60% nitrous oxide and 1% isoflurane. An initial dose of vecuronium was administered and patients' tracheas were intubated.

MEASUREMENTS

Neuromuscular function was monitored by acceleration of thumb adduction with train-of-four stimulation. Vecuronium 60 microg x kg(-1) was administered as the initial dose via a central catheter, and if the first twitch was more than 3% of the control, another dose of vecuronium 20 microg x kg(-1) was given as necessary. Both onset time and duration of action until 25% recovery were measured. Plasma vecuronium and its metabolite, 3-desacetyl-vecuronium, levels were measured at onset and at 25% recovery in Groups A and C.

MAIN RESULTS

The total dose of vecuronium and initial concentration of vecuronium showed no significant difference between Group A and Group C. Duration of action was significantly prolonged in Group A and Group B compared with Group C.

CONCLUSIONS

Duration of action of vecuronium is prolonged in patients with end-stage renal failure mainly due to higher sensitivity to vecuronium.

Optimization of transcriptional regulatory elements for constructing plasmid vectors

In studies regarding both gene therapy and gene function, transgene expression by plasmid vectors benefits from the use of transcriptional regulatory elements which permit high-level gene expression. Therefore, with respect to transgene (luciferase) expression activity both in vitro (using HeLa, HepG2, and ECV304 cells) and in vivo (mouse liver and skeletal muscle), we investigated the effective combination of commonly-used regulatory elements, such as the promoter/enhancer, intron, and polyadenylation signal (P(A)) sequence by constructing a series of plasmids that differed only in the particular sequence element being evaluated. Of the several promoter/enhancers that were tested, hybrid CA promoter/enhancer containing human cytomegalovirus immediate-early 1 gene (CMV) enhancer and chicken beta-actin promoter with the beta-actin intron sequence, and the improved CMV promoter/enhancer containing the largest intron of CMV (intron A) produced the highest levels of expression both in vitro and in vivo. P(A) sequences were found to have significant effects on transgene expression. The effect of a multiple enhancer was also examined. Optimized plasmids of this study were pCASL3 (composed of CMV enhancer, beta-actin promoter, beta-actin intron, Simian virus (SV40) P(A) sequence and SV40 enhancer) and pCMVSL3 (composed of CMV enhancer, CMV promoter, intron A, SV40 P(A) sequence and SV40 enhancer). These comparative analyses could provide a systematic reference for the development of vector construction for gene therapy, vaccine development, and gene transfer experiments.

Amino acids and peptides. Part 39: A bivalent poly(ethylene glycol) hybrid containing an active site (RGD) and its synergistic site (PHSRN) of fibronectin

Fibronectin contains the active sequence Arg-Gly-Asp (RGD), along with its synergic site Pro-His-Ser-Arg-Asn (PHSRN). However, the PHSRN peptide does not show synergic activity when it is mixed with the RGD peptide, indicating that a spatial array between RGD and PHSRN in fibronectin may be necessary for synergic activity. Here, we have used an amino acid type poly(ethylene glycol) derivative (aaPEG) to design a bivalent PEG hybrid of fibronectin active peptides. We prepared the aaPEG hybrid peptides PHSRN-aaPEG, aaPEG-RGD, and PHSRN-aaPEG-RGD, and tested their biological activity. Whereas aaPEG-RGD promoted cell spreading activity, PHSRN-aaPEG had no activity. The PHSRN-aaPEG-RGD hybrid strongly promoted cell spreading compared with aaPEG-RGD. These results suggest that the PHSRN sequence in the PHSRN-aaPEG-RGD molecule synergistically enhances the cell spreading activity of the RGD sequence, and that the bivalent aaPEG hybrid method may be useful for conjugating functionally active peptides.

Administration route-dependent vaccine efficiency of murine dendritic cells pulsed with antigens

Dendritic cells (DCs) loaded with tumour antigens have been successfully used to induce protective tumour immunity in murine models and human trials. However, it is still unclear which DC administration route elicits a superior therapeutic effect. Herein, we investigated the vaccine efficiency of DC2.4 cells, a murine dendritic cell line, pulsed with ovalbumin (OVA) in the murine E.G7-OVA tumour model after immunization via various routes. After a single vaccination using 1 x 10(6)OVA-pulsed DC2.4 cells, tumour was completely rejected in the intradermally (i.d.; three of four mice), subcutaneously (s.c.; three of four mice), and intraperitoneally (i.p.; one of four mice) immunized groups. Double vaccinations enhanced the anti-tumour effect in all groups except the intravenous (i.v.) group, which failed to achieve complete rejection. The anti-tumour efficacy of each immunization route was correlated with the OVA-specific cytotoxic T lymphocyte (CTL) activity evaluated on day 7 post-vaccination. Furthermore, the accumulation of DC2.4 cells in the regional lymph nodes was detected only in the i.d.-and s.c.-injected groups. These results demonstrate that the administration route of antigen-loaded DCs affects the migration of DCs to lymphoid tissues and the magnitude of antigen-specific CTL response. Furthermore, the immunization route affects vaccine efficiency.

[Application of novel drug delivery system, fusogenic liposome, for cancer therapy]

Over the past decade, many studies concerning novel anti-cancer therapies have been reported. It has been occasionally noted that a powerful anti-cancer drug, especially one whose target is the cytoplasm or cell nucleus, does not work due to the low permeability across a plasma membrane, degradation by lysosomal enzymes through an endocytosis-dependent pathway, and other reasons. Thus, several approaches using drug delivery systems (DDS) are focused on overcoming these difficulties, eventually leading to the induction of maximal ability of anti-cancer drug. In this respect, we have developed a new paradigm for cancer therapy using a novel drug delivery system, fusogenic liposome. Fusogenic liposomes are composed of the ultraviolet-inactivated Sendai virus and conventional liposomes. Fusogenic liposomes effectively and directly deliver their encapsulated contents into the cytoplasm using a fusion mechanism of the Sendai virus, whereas conventional liposomes are taken up by endocytosis. Thus, fusogenic liposome is a good candidate as a vehicle to deliver drugs into the cytoplasm in an endocytosis-independent manner. In this report, we show the feasibility of fusogenic liposome as a delivery vehicle for anti-cancer drugs using a fragment A of diphtheria toxin as an anti-cancer reagent. We also demonstrate the application of fusogenic liposome for cancer gene therapy and cancer vaccines using a TNF-alpha-expression plasmid and a chicken egg ovalbumin, respectively.

Amino acids and peptides. XXXVIII. Facile synthesis of laminin-related peptide-poly(ethylene glycol) hybrids by the solid phase method

Poly(ethylene glycol) (PEG) has been studied as a drug-carrier for proteins, but not for small peptides. Laminin, a cell adhesive protein, has Tyr-Ile-Gly-Ser-Arg (YIGSR) sequence and peptides containing this sequence inhibit experimental metastasis. We have studied PEG hybrids of YIGSR and other small laminin-related peptides. In a previous paper, we reported preparation of YIGSR-PEG hybrids by combination of the solid phase method and the solution method, but the synthetic procedure was problematic. Here we report a facile synthesis of PEG hybrids of YIGSR (PEG-YIGSR, YIGSR-PEG, PEG-YIGSR-PEG) by the solid phase method.

Efficient gene delivery into dendritic cells by fiber-mutant adenovirus vectors

Recent studies have demonstrated the usefulness of dendritic cells (DCs) genetically modified by adenovirus vectors (Ad) to immunotherapy, while sufficient gene transduction into DCs is required for high doses of Ad. The RT-PCR analysis revealed that the relative resistance of DCs to Ad-mediated gene transfer is due to the absence of Coxsackie-adenovirus receptor expression, and that DCs expressed adequate alpha(v)-integrins. Therefore, we investigated whether fiber-mutant Ad containing the Arg-Gly-Asp (RGD) sequence in the fiber knob can efficiently transduce and express high levels of the LacZ gene into DCs. The gene delivery by fiber-mutant Ad was more efficient than that by conventional Ad in both murine DC lines and normal human DCs (NHDC). Furthermore, NHDC transduced with fiber-mutant Ad and conventional Ad at 8000-vector particles/cell resulted in a 70-fold difference in beta-galactosidase activity. We propose that alpha(v)-integrin-targeted Ad is a very powerful tool with which to implement DC-based vaccination strategies.

[The occurrence of Churg-Strauss syndrome in two patients with remitted asthma]

We report two patients with Churg-Strauss syndrome (CSS) which occurred on the remission stage of bronchial asthma. Case 1 of a 64-year-old woman suffered from asthma in June, 1997, and got relief with treatment. In February, 1998, dysesthesia, pain and severe muscle weakness occurred in the extremities and erythematous rashes appeared on the extremities and back. She was transferred to our hospital on March 3. Peripheral blood eosinophilia was observed and a diagnosis of CSS was made. Eosinophilic tissue infiltration and vasculitis was found in the skin biopsy specimen. She was treated with prednisolone (60 mg/day) with moderate improvement. But the dysesthesia in the extremities, bilateral foot drop and the weakness of the left hand grasping power continued. Case 2 of a 62-year-old woman suffered from asthma in 1995, which improved by treatment. In March 1998, dysesthesia and pain in the lower extremities occurred and progressed. Erythematous rashes appeared on the feet and she was admitted to our hospital in May. Peripheral blood eosinophilia and eosinophilic tissue infiltration in the skin biopsy specimen were observed and a diagnosis of CSS was made. The treatment with prednisolone (60 mg/day) improved the pain but the dysesthesia continued. It is important to know the occurrence of CSS on the remission stage of bronchial asthma.

Co-production of microcystins and aeruginopeptins by natural cyanobacterial bloom

The relationship between Microcystis composition and the production of microcystins and nontoxic peptides in bloom cells, which was regularly collected in Lake Suwa, Japan, in the summer season from 1991 to 1994, was investigated. In order to determine the structures of the nontoxic peptides, we collected large amounts of bloom materials from the same lake on July 23, 1991, and isolated three nontoxic peptides. They were named as aeruginopeptins 917S-A, -B, and -C, and their structures were mainly determined by a mass spectrometry/mass spectrometry (MS/MS) technique as 19-membered cyclic depsipeptides possessing the Ahp (3-amino-6-hydroxy-2-piperidone) moiety. An analysis of the microcystins and aeruginopeptins in the collected blood cells and their Microcystis composition suggested that the M. aeruginosa large cell size produces both microcystins and aeruginopeptins, and the production of both compounds is genetically closely related.

Selective enhancement of thrombopoietic activity of PEGylated interleukin 6 by a simple procedure using a reversible amino-protective reagent

We developed a novel method for the chemical modification of cytokines with synthetic polymers to increase the therapeutic efficacy of the former in vivo. A pH-reversible amino-protective reagent, dimethylmaleic anhydride (DMMAn), was used for modification of interleukin-6 (IL-6) with polyethylene glycol (PEG). The novel PEG-conjugated IL-6 (DmPEG-IL-6), which had been pretreated with DMMAn before PEGylation, showed up to a 140% increase in in vitro specific activity compared with PEG-IL-6 that had been synthesized by the previous method. Moreover, DmPEG-IL-6 caused thrombopoiesis more potently in mice than PEG-IL-6. The DmPEG-IL-6 Fr.1, having 3-4 PEG chains attached to the cytokine, showed the strongest thrombopoietic effect among the DmPEG-IL-6s with different molecular sizes that were tested. PEG-IL-6 Fr.1 had a 500-fold higher potency in stimulating thrombopoiesis than native IL-6 and DmPEG-IL-6 Fr.1 achieved a threefold higher thrombopoietic effect than PEG-IL-6 Fr.1. In addition, side-effects, such as an increase in the plasma fibrinogen level, were not observed after injection of either PEG-IL-6s or DmPEG-IL-6s. These results suggest that PEGylation with DMMAn pretreatment may become a useful means for clinical cytokine delivery.

Effective cancer targeting using an anti-tumor tissue vascular endothelium-specific monoclonal antibody (TES-23)

Immunoconjugate targeting of solid tumors has not been routinely successful because the endo-thelial cells of blood vessels act as a physical barrier against the transport of macromolecules, such as antibodies. In the present study, we attempted to achieve tumor vascular targeting with an anti-tumor tissue endothelium-specific monoclonal antibody (TES-23). TES-23, an IgG1 monoclonal antibody raised against rat KMT-17 fibrosarcoma-derived endothelial cells, was covalently conjugated with neocarzinostatin (NCS) in a previous study. The TES-23-NCS conjugate induced tumor hemorrhagic necrosis, and showed marked anti-tumor effects against rat KMT-17 fibrosarcoma. This result prompted us to investigate whether this approach would be applicable to various other types of solid tumors. One hour after injection of (125)I-labeled TES-23 into BALB / c mice bearing Meth-A fibrosarcoma and Colon 26 adenocarcinoma, the tumor accumulation of TES-23 was greater than that of the control IgG. In the present study, we report the anti-tumor effects of this monoclonal antibody in mice bearing Meth-A fibrosarcoma. Mice treated with the immunoconjugate showed improved survival with no side effects. This result indicates that common antigens may be found in different kinds of tumor endothelial cells, and that TES-23 might recognize these antigens.

Antitumor activity of tumor necrosis factor-alpha conjugated with polyvinylpyrrolidone on solid tumors in mice

We attempted the development of a novel polymer conjugation to further improve the therapeutic potency of antitumor cytokines compared with PEGylation for clinical application. Compared with native tumor necrosis factor (TNF)-alpha in vitro, specific bioactivities of polyvinyl-pyrrolidone (PVP)-modified TNF-alphas (PVP-TNF-alphas) were decreased by increasing the degree of PVP attachment. PVP-TNF-alpha fraction 3, Mr 101,000, had the most effective antitumor activity of the various PVP-TNF-alphas in vivo. PVP-TNF-alpha fraction 3 had >200-fold higher antitumor effect than native TNF-alpha, and the antitumor activity of PVP-TNF-alpha fraction 3 was >2-fold higher than that of MPEG-TNF-alpha (Mr 108,000), which had the highest antitumor activity among the polyethylene glycol (PEG)-conjugated TNF-alphas. Additionally, a high dose of native TNF-alpha induced toxic side effects such as body weight reduction, piloerection. and tissue inflammation, whereas no side effects were observed after i.v. administration of PVP-TNF-alpha fraction 3. The plasma half-life of PVP-TNF-alpha fraction 3 (360 min) was about 80- and 3-fold longer than those of native TNF-alpha (4.6 mm) and MPEG-TNF-alpha (122 min), respectively. The mechanism of increased antitumor effect in vivo caused the prolongation of plasma half-life and increase in stability. These results suggested that PVP is a useful polymeric modifier for bioconjugation of TNF-alpha to increase its antitumor potency, and multifunctionally bioconjugated TNF-alpha may be a potentiated antitumor agent for clinical use.

Human tumor necrosis factor-alpha mutant RGD-V29 (F4614) shows potent antitumor activity and reduced toxicity against human tumor xenografted nude mice

The antitumor effects of human tumor necrosis factor-alpha (TNF) mutant RGD-V29 (code no. F4614), that includes the cell adhesive sequence (4)Arg-(5)Gly-(6)Asp and (29)Arg-->Val substitution, were evaluated. The therapeutic index, a measure of the extent of the therapeutically-effective range, using three constitutive administrations of RGD-V29 in Meth A-bearing mice was 4.8, whereas that of recombinant human TNF (rhTNF) ((1)SSS(4)RTPSDK...(29)RR...(155)L) was 2.8, clearly indicating that the effective RGD-V29 dose-range was extended. Furthermore, RGD-V29 showed potent antitumor activity against human lung cancer Mqnu-1 xenografted nude mice without severe gastrointestinal and other organ toxicities, even when administered at the maximal tolerated dose (MTD). In contrast, rhTNF induced severe toxicity at the MTD. Direct cytotoxicity of RGD-V29 against Mqnu-1 cells was similar to that of rhTNF. In addition, a cytotoxicity assay using a tumor-derived endothelial-like cell (tEC)/normal endothelial cell (nEC) system used to study TNF antitumor effects on tumor-associated endothelial cells, suggested that RGD-V29 showed preferential cytotoxicity toward tumor-associated endothelial cells compared with rhTNF. Thus, RGD-V29 appears to be a low-toxicity mutant of rhTNF that shows preferential activity towards tumors, and therefore merits further investigation in pre-clinical and clinical studies.

Characterization of mucoadhesive microspheres for the induction of mucosal and systemic immune responses

In the present study, mucoadhesive polymer-dispersed microspheres (MS) were examined as a potential mucosal vaccine carrier. A major focus of the study was aimed at directly assessing the influence of antigen release and persistence in the mouse small intestine for the induction of mucosal and systemic immune responses. BALB/c mice were immunized with various forms of MS containing chicken egg ovalbumin (OVA) by administration into the duodenum. No detectable anti-OVA immune responses were observed following the administration of OVA alone or that of MS without mucoadhesive polymer (MS-0). MS-10 containing 10% mucoadhesive polymer rapidly released OVA and hardly induced anti-OVA antibody responses in either serum or fecal extracts. In contrast, MS-8 and MS-6 (with 8 and 6% mucoadhesive polymer) showed controlled release of OVA, which elicited strong OVA-specific IgG and IgA responses in serum and fecal extracts, respectively. Additionally, the strongest immune responses were induced in mice immunized with MS-8, which had both the optimal release-profile of OVA and the longest persistence in the small intestine. These findings indicate that antigen movement in the small intestine is an important factor and that appropriate microsphere forms with mucoadhesive polymers might be useful candidates as mucosal vaccine carriers.

Improvement of intestinal absorption of macromolecules by nitric oxide donor

Nitric oxide (NO) is one of the most versatile mediators in mammalian biology. In the present study, we investigated the absorption-enhancing effects of an NO donor, 3-(2-hydroxy-1-methylethyl-2-nitrosohydrazino)-N-methyl-1-propa namine (NOC7), on drugs that are poorly absorbed from the gastrointestinal tract. NOC7 significantly increased the jejunal absorption of fluorescein isothiocyanate dextrans (FDs) of different average molecular weights (4000-20,000). This enhancing effect decreased as the FD molecular weight increased. Another NO donor, S-nitroso-N-acetyl-DL-penicillamine (SNAP), also increased the absorption of FD-4 from the jejunum. The absorption enhancement effect of NOC7 significantly decreased after coadministration with an NO scavenger, 2-(4-carboxyphenyl)-4,4,5, 5-tetramethylimidazole-1-oxyl-3-oxide, sodium salt. Furthermore, the enhancement effect of NOC7 was reversed shortly after cessation of the enhancer treatment. Little damage by NOC7 to the intestinal mucosa was observed in terms of release of lactose dehydrogenase and protein from the intestinal mucosa. NOC7 also increased the absorption of FD-4 by the colon and rectum. The findings suggest that an NO donor can improve the absorption of macromolecules from all regions of the rat intestine with very little mucosal damage and that an NO donor can act as a potent absorption enhancer.

Molecular design of polyvinylpyrrolidone-conjugated interleukin-6 for enhancement of in vivo thrombopoietic activity in mice

Functional polyvinylpyrrolidone (PVP) was synthesized as a novel polymeric modifier for polymer-conjugated cytokines, and its efficiency and applicability as a drug delivery system (DDS) were evaluated. PVP with a carboxyl group at one end of the main chain was prepared by radical polymerization (M(n): 6000, M(w)/M(n): 1.14) with the aid of 4,4'-azobis(4-cyanovaleric acid) as a radical initiator and 3-mercaptopropionic acid as a transfer agent. Interleukin-6 (IL-6) was covalently conjugated via the formation of amino bonds between the lysine amino groups of IL-6 and PVP. PVP-conjugated IL-6, in which 60% of the fourteen lysine amino groups of IL-6 were estimated to be coupled with PVP (M-PVP-IL-6), showed more than 50-fold greater thrombopoietic potency in vivo than native IL-6. No side effects, such as body weight loss, were observed in the M-PVP-IL-6 treated mice. These results indicate that PVP as a polymeric modifier is a promising DDS for clinical application of cytokines and other therapeutic agents.

A novel nonviral vector based on vesicular stomatitis virus

Here we report a simple and efficient method for nonviral gene transfer using liposomes which have envelope protein of vesicular stomatitis virus (VSV) on their surface (VSV-liposomes). We prepared VSV-liposome by fusing simple liposomes with VSV particles. The density of VSV-liposome fusion products was intermediated between that of liposomes and that of VSV particles. Furthermore, VSV-liposome fusion products included both viral proteins and lipids from liposomes, and were confirmed to be fusion products, but not adsorptive products, by the resonance energy transfer fusion assay. To evaluate whether these particles can efficiently introduce their internal contents into the cytoplasm of mammalian cells, we examined the delivery of fragment A of diphtheria toxin (DTA) by VSV-liposomes into the cytoplasm of FL cells. We found that VSV-liposomes encapsulating DTA were highly cytotoxic to the cells, while empty VSV-liposomes and plain liposomes encapsulating DTA were not, suggesting that VSV-liposomes delivered DTA into cytoplasm. Consistent with this, the cells cultured with plasmid DNA entrapped in VSV-liposomes and coding for firefly luciferase showed significant luciferase expression, whereas cells culture with plasmid DNA in plain liposomes and plasmid DNA-cationic liposomes complex did not. Thus, VSV-liposomes function as a simple and efficient nonviral vector for the delivery of DNA.

Growth inhibition of human leukemia HL-60 cells by an antisense phosphodiester oligonucleotide encapsulated into fusogenic liposomes

We report here the antisense effect of phosphodiester oligodeoxynucleotide (D-ODN) using fusogenic liposomes (FL) as its carrier. FL has envelope proteins of the Sendai virus within its membrane and introduces its contents directly and efficiently into cytosol by means of the virus-cell fusion mechanism. Using antisense (AS) D-ODN 15-mer complementary to the c-myc proto-oncogene mRNA, including the translation initiation codon site, we analyzed the growth of HL-60 cells by [3H]-thymidine uptake. AS-ODNs encapsulated in FL inhibited the growth by about 70% that of the control HL-60 cells at 2.48 microM. In contrast, sense and scramble D-ODNs encapsulated in FL showed no effect of the growth of HL-60 cells at the same concentration. Even at 50 microM, free form D-ODNs did not show any effect. These results suggest that FL is potentially a useful delivery vehicle for oligonucleotide-based therapeutics, and that D-ODN may be a likely candidate for oligodeoxynucleotides when an efficient delivery system is used.

Association of CD44 with OTS-8 in tumor vascular endothelial cells

Endothelial cells in solid tumors play an important role in tumor growth, invasion and metastasis through angiogenesis. We have recently cloned two tumor vascular antigens from isolated rat tumor vascular endothelial cells (TEC). One is CD44, a family of cell surface proteins implicated in adhesion interactions and tumor metastasis. The other is OTS-8, a marker for osteoblast into osteocyte transition and type I alveolar epithelial cells termed as E11 antigen and RTI40, respectively. To test for a possible interaction between the two antigens on endothelial cells in tumor angiogenesis, we examined in vivo association of CD44 with OTS-8 using lysates of isolated rat TEC and COS-7 cells cotransfected with CD44 and OTS-8 expression plasmids. The association was detected by direct co-immunoprecipitation of the two types of cells lysed with digitonin, whereas the detection was lost when lysed with Nonidet P-40. To confirm this association, intact COS-7 cells cotransfected were reacted with homobifunctional N-hydroxysuccinimide ester crosslinking reagents. Immunoblot analysis showed a crosslinked CD44/OTS-8 protein complex of 120 kDa, suggesting the proximity of the two proteins. These findings provide evidence of a weak physical association between CD44 and OTS-8 in TEC, and suggest that OTS-8 may alter the mode of endothelial cell growth and/or migration induced by CD44 in tumor angiogenesis.

Molecular cloning and characterization of antigens expressed on rat tumor vascular endothelial cells

We have previously prepared monoclonal antibodies (MAbs) against tumor vasculature using cultured rat tumor endothelial cells (TECs) isolated from solid KMT-17 tumors and identified 40 and 80 kDa antigens recognized by TES-17 and TES-23 MAbs, respectively. To clarify the nature of antigens on tumor vasculature, molecular cloning was conducted by screening the rat TEC cDNA library. Two antigens were detected: a 40 kDa OTS-8 antigen, which had been defined as a differentiation marker for osteoblastic lineage, and an 80 kDa CD44H antigen. Northern blots showed that OTS-8 mRNA was expressed exclusively in the lung, in addition to TECs, while CD44H mRNA was detected in the lung, intestine, spleen, thymus and peripheral blood cells, in addition to TECs. Immuno-histochemistry of KMT-17 tumors revealed that OTS-8 and CD44 were expressed on sprouting TECs. In addition, TES-23 MAb stained TECs of tubular vessels as well as sprouting TECs, but anti-rat CD44 MAbs stained only sprouting TECs. PCR showed that CD44 cDNA with a splice in exon 6 (CD44ex6) was present in rat TECs at low levels. Our results indicate that OTS-8 and CD44 are expressed on rat sprouting TECs and that TES-23 MAb recognizes CD44H on sprouting TECs as well as an unknown epitope on TECs of tubular vessels that could not be recognized by anti-rat CD44 MAbs.

Fusogenic liposomes efficiently deliver exogenous antigen through the cytoplasm into the MHC class I processing pathway

Exogenous soluble proteins enter the endosomal pathway by endocytosis and are presented in association with MHC class II rather than class I. In contrast, the delivery of exogenous protein antigens (Ag) into the cytosol generates MHC class I-restricted cytotoxic T lymphocytes (CTL) responses. Although several immunization approaches, such as the utilization of liposomes, have induced the in vivo priming of MHC class I-restricted CTL responses to protein Ag, it remains unclear whether this priming results from the direct delivery of protein Ag to the cytosol. Here we report that fusogenic liposomes (FL), which are prepared by fusing simple liposomes with Sendai virus particles, can deliver the encapsulated soluble protein directly into the cytosol of cells cultured concurrently and introduce it into the conventional MHC class I Ag presentation pathway. Moreover, a single immunization with ovalbumin (OVA) encapsulated in FL but not in simple liposomes results in the potent priming of OVA-specific CTL. Thus, FL function as an efficient tool for the delivery of CTL vaccines.

Recognition of human activated CD44 by tumor vasculature-targeted antibody

TES-23 monoclonal antibody (MAb), which targets rat CD44H on tumor vascular endothelial cells (TEC), dominantly reacted to human activated CD44 rather than human inactive CD44. TES-23 MAb reacted to HT-1080 fibrosarcoma cells almost comparably to anti-human CD44 MAb and moderately to HUVEC; however, it hardly reacted to PBMC. The binding of soluble hyaluronate to HT-1080 cells and HUVEC was clearly noted, but not to PBMC. In addition, stimulation with phorbol 12-myristate 13-acetate induced soluble hyaluronate binding of MOLT-4 human T lymphoma cells and relatively increased the reactivity of TES-23 MAb. Our results suggest that TES-23 MAb can potentially recognize human activated CD44 and hence might be potentially useful for the treatment of human solid tumors containing TEC that express activated CD44.

[Targeting therapy using a monoclonal antibody against tumor vascular endothelium]

Recent studies have revealed that the targeting therapy using monoclonal antibody against tumor associated antigens did not have a clinically satisfactory effect due to various physiological characters of tumor. We propose a novel approach targeting tumor vascular endothelium to solve the inefficiency of common tumor missile therapy. In this study, the tissue distribution of anti-tumor vascular endothelium monoclonal antibody (TES-23) produced by immunizing with plasma membrane vesicles obtained from isolated rat tumor-derived endothelial cells (TECs) was assessed in various tumor-bearing animals. Radiolabeled TES-23 dramatically accumulated in KMT-17 fibrosarcoma, a source of isolated TECs after intravenous injection. In Meth-A fibrosarcoma, Colon-26 adenocarcinoma in BALB/c mice and HT-1080 human tumor tissue in nude mice, radioactivities of 125I-TES-23 were also up to fifty times higher than those of control antibody with little distribution to normal tissues. Furthermore, immunostaining of human tissue sections showed specific binding of TES-23 on endothelium in esophagus and colon cancers. These results indicate that tumor vascular endothelial cells express a common antigen in different tumor types of various animal species. In order to clarify the efficacy of TES-23 as a drug carrier, an immunoconjugate, composed of TES-23 and neocarzinostatin, was tested for its antitumor effect in vivo. The immunoconjugate (TES-23-NCS) caused a marked regression of the tumor, KMT-17 in rats and Meth-A in mice. Thus, from a clinical view, TES-23 would be a novel drug carrier because of its high specificity to tumor vascular endothelium and its application to many types of cancer.

In vitro remodeling of tumor vascular endothelial cells using conditioned medium from various tumor cells and their sensitivity to TNF-alpha

Prevention of tumor-associated blood vessel formation (angiogenesis) is a potentially powerful strategy to treat cancer. We found that tumor vascular endothelial cells were rearranged in vitro with conditioned culture medium derived from tumor cells and compared the sensitivity to the effects of TNF-alpha between normal and tumor endothelial cells. Incubation with tumor (Meth-A, Colon26)-derived conditioned medium showed that no effect was observed on cell growth. Tumor cells (Meth-A, Colon26, and B16BL6) only showed no sensitivity to TNF-alpha. Normal and control endothelial cells in culture showed little cytotoxicity in response to TNF-alpha treatment, but marked cytotoxicity of TNF-alpha was observed in endothelial cells cultured with tumor-derived conditioned medium. Sensitivity to TNF-alpha was different depending on the type of tumor from which the conditioned medium was derived. This difference in sensitivity was assumed to be due to the in vivo sensitivity to TNF-alpha. The results of this study suggested that the sensitivity of tumors to TNF-alpha is controlled by the sensitivity of tumor vasculature.