Bovine pestivirus is a new alternative virus for multiple myeloma oncolytic virotherapy

BACKGROUND

The oncolytic viruses have shown promising results for the treatment of multiple myeloma. However, the use of human viruses is limited by the patients' antiviral immune response. In this study, we investigated an alternative oncolytic strategy using non-human pathogen viruses as the bovine viral diarrhea virus (BVDV) that were able to interact with CD46.

METHODS

We treated several human myeloma cell lines and non-myeloma cell lines with BVDV to evaluate the expression of CD46 and to study the effect on cell viability by flow cytometry. The possible synergistic effect of bortezomib in combination with BVDV was also tested. Moreover, we infected the bone marrow mononuclear cells obtained from myeloma patients and we checked the BVDV effect on different cell populations, defined by CD138, CD14, CD3, CD19, and CD56 expression evaluated by flow cytometry. Finally, the in vivo BVDV effect was tested in NOD-SCID mice injected subcutaneously with myeloma cell lines.

RESULTS

Human myeloma cells were selectively sensitive to BVDV treatment with an increase of cell death and, consequently, of apoptotic markers. Consistently, bone marrow mononuclear cells isolated from myeloma patients treated with BVDV, showed a significant selective decrease of the percentage of viable CD138+ cells. Interestingly, bortezomib pre-treatment significantly increased the cytotoxic effect of BVDV in myeloma cell lines with a synergistic effect. Finally, the in vitro data were confirmed in an in vivo myeloma mouse model showing that BVDV treatment significantly reduced the tumoral burden compared to the vehicle.

CONCLUSIONS

Overall, our data indicate, for the first time, a direct oncolytic effect of the BVDV in human myeloma cells suggesting its possible use as novel alternative anti-myeloma virotherapy strategy.

The local complement activation on vascular bed of patients with systemic sclerosis: a hypothesis-generating study

Objective

The role of complement system in the pathogenesis of systemic sclerosis (SSc) has been debated during the last decade but an evident implication in this disease has never been found. We carried out an explorative study on SSc patients to evaluate the expression of soluble and local C5b-9 complement complex and its relation with a complement regulator, the Membrane Cofactor Protein (MCP, CD46) on skin vascular bed as target distinctive of SSc disease. We also analyzed two polymorphic variants in the complement activation gene cluster involving the MCP region.

Methods

C5b-9 plasma levels of SSc patients and healthy subjects were analyzed by ELISA assay. Archival skin biopsies of SSc patients and controls were subjected to immunofluorescence analysis to detect C5b-9 and MCP on vascular endothelial cells. The expression of MCP was validated by immunoblot analysis with specific antibody. Polymorphic variants in the MCP gene promoter were tested by a quantitative PCR technique-based allelic discrimination method.

Results

Even though circulating levels of C5b-9 did not differ between SSc and controls, C5b-9 deposition was detected in skin biopsies of SSc patients but not in healthy subjects. MCP was significantly lower in skin vessels of SSc patients than in healthy controls and was associated with the over-expression of two polymorphic variants in the MCP gene promoter, which has been related to more aggressive phenotypes in other immune-mediated diseases.

Conclusions

Our results firsty document the local complement activation with an abnormal expression of MCP in skin vessels of SSc patients, suggesting that a subset of SSc patients might be exposed to more severe organ complications and clinical evolution due to abnormal local complement activation.

A novel CDX2 isoform regulates alternative splicing

Gene expression is a dynamic and coordinated process coupling transcription with pre-mRNA processing. This regulation enables tissue-specific transcription factors to induce expression of specific transcripts that are subsequently amplified by alternative splicing allowing for increased proteome complexity and functional diversity. The intestine-specific transcription factor CDX2 regulates development and maintenance of the intestinal epithelium by inducing expression of genes characteristic of the mature enterocyte phenotype. Here, sequence analysis of CDX2 mRNA from colonic mucosa-derived tissues revealed an alternatively spliced transcript (CDX2/AS) that encodes a protein with a truncated homeodomain and a novel carboxy-terminal domain enriched in serine and arginine residues (RS domain). CDX2 and CDX2/AS exhibited distinct nuclear expression patterns with minimal areas of co-localization. CDX2/AS did not activate the CDX2-dependent promoter of guanylyl cyclase C nor inhibit transcriptional activity of CDX2. Unlike CDX2, CDX2/AS co-localized with the putative splicing factors ASF/SF2 and SC35. CDX2/AS altered splicing patterns of CD44v5 and Tra2-β1 minigenes in Lovo colon cancer cells independent of CDX2 expression. These data demonstrate unique dual functions of the CDX2 gene enabling it to regulate gene expression through both transcription (CDX2) and pre-mRNA processing (CDX2/AS).

Gene therapy using adenovirus against malignant mesothelioma

BACKGROUND

Adenovirus vectors have been utilized for cancer gene therapies. The present study examined the oncolytic effects of adenovirus type 5 (Ad5) and fiber-substituted conditionally replicating adenovirus (CRAD) Ad5/F35 vectors on the human malignant mesothelioma cells MSTO-211H, NCI-H28, NCI-H2052, and NCI-H2452 cells.

MATERIALS AND METHOD

For the adenovirus, the first mRNA/protein to be made (~1 h after infection) is E1A. Ad5F35 and Ad5 CRAD vectors containing the E1 gene controlled by the human midkine promoter (Ad5F35/MKp-E1 and Ad5/MKp-E1, respectively) were constructed. Western blotting and cell viability assays were carried out in cells transfected with Ad5/MKp-E1 and Ad5F35/MKp-E1.

RESULTS

Coxsackie and adenovirus receptor (CAR), a cell surface target of Ad5, and CD46, a cell surface target of Ad35, were expressed in all the malignant mesothelioma cell lines examined here, as much as in HEK293 cells, with no significant differences in the expression levels among cells. Both Ad5/MKp-E1 and Ad5F35/MKp-E1 induced oncolysis of malignant mesothelioma cells in a viral particle-dependent manner, with similar efficacy.

CONCLUSION

The results of the present study suggest that both Ad5/MKp-E1 and Ad5F35/MKp-E1 are useful for the gene therapy of human malignant mesothelioma.

Fiber-substituted conditionally replicating adenovirus for oncolysis of human renal carcinoma cells

BACKGROUND

Adenovirus vectors have lately been highlighted in gene therapies. We investigated the oncolytic effects of a chimeric adenovirus type 5 (Ad5) with replacement of Ad5 fiber knob with adenovirus type 35 (Ad35) fiber knob (Ad5F35) on human renal cell carcinoma (RCC).

MATERIALS AND METHODS

The conditionally replicating Ad5F35 vector was constructed and infected into RCC cell lines 786-O, ACHN, and RCC4-VHL. For these cells, reverse transcription-polymerase chain reaction and western blotting were carried out and the cell viability was assayed.

RESULTS

In all RCC cell lines, it was found that CD46, a cell surface target of Ad35, was well-expressed, while coxsackie and adenovirus receptor (CAR), a cell surface target of Ad5, was considerably less expressed. The Ad5F35 vector induced oncolysis of RCC cells, with significantly higher efficacy as compared with that for the Ad5 vector.

CONCLUSION

Ad5F35 vector could be a candidate for promising gene therapy of human RCC.

Expression of complement regulatory proteins CD55, CD59, CD35, and CD46 in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease associated with polyarticular inflammatory synovitis affecting mainly peripheral joints. It affects approximately 1% of the world population, being two to three times more prevalent in women. Rheumatoid arthritis has a complex and multifactorial pathogenesis. The synovium of the affected joints is infiltrated by T and B lymphocytes, macrophages, and granulocytes. The rheumatoid synovium has proliferative characteristics, forming the pannus, which invades cartilage and bone, leading to normal architecture destruction and function loss. The decreased expression of complement regulatory proteins (CRP) seems to play an important role in RA activity, and is associated with worsening of the clinical symptoms. In several models of autoimmune diseases, the overactivation of the complement system (CS) is the cause of disease exacerbation. This article aimed at reviewing the main aspects related to CS regulation in RA in order to provide a better understanding of the potential role of this system in the pathophysiology and activity of the disease.

Atorvastatin or transgenic expression of TFPI inhibits coagulation initiated by anti-nonGal IgG binding to porcine aortic endothelial cells

BACKGROUND

Intravascular thrombosis remains a barrier to successful xenotransplantation. Tissue factor (TF) expression on porcine aortic endothelial cells (PAECs), which results from their activation by xenoreactive antibodies (Abs) to Galα1,3Gal (Gal) and subsequent complement activation, plays an important role.

OBJECTIVES

The present study aimed to clarify the role of Abs directed against nonGal antigens in the activation of PAECs to express functional TF and to investigate selected methods of inhibiting TF activity.

METHODS

PAECs from wild-type (WT), α1,3-galactosyltransferase gene-knockout (GT-KO) pigs, or pigs transgenic for CD46 or tissue factor pathway inhibitor (TFPI), were incubated with naïve baboon serum (BS) or sensitized BS (with high anti-nonGal Ab levels). TF activity of PAECs was assessed.

RESULTS

Only fresh, but not heat-inactivated (HI), naïve BS activated WT PAECs to express functional TF. Similarly, PAECs from CD46 pigs were resistant to activation by naïve BS, but not to activation by fresh or HI sensitized BS. HI sensitized BS also activated GT-KO PAECs to induce TF activity. TF expression on PAECs induced by anti-nonGal Abs was inhibited if serum was pretreated with (i) an anti-IgG Fab Ab or (ii) atorvastatin, or (iii) when PAECs were transgenic for TFPI.

CONCLUSIONS

Anti-nonGal IgG Abs activated PAECs to induce TF activity through a complement-independent pathway. This implies that GT-KO pigs expressing a complement-regulatory protein may be insufficient to prevent the activation of PAECs. Genetic modification with an 'anticoagulant' gene (e.g. TFPI) or a therapeutic approach (e.g. atorvastatin) will be required to prevent coagulation dysregulation after pig-to-primate organ transplantation.

[Co-expression and synergic effect of human complement regulatory proteins DAF and MCP]

Recombinant expression vector pcDNA3-DAFMCP-DP containing human membrane complement regulatory proteins (hCRPs) decay accelerating factor (DAF) and membrane cofactor protein (MCP) cDNA was constructed by using two independent promoters. After transfected into NIH3T3 cells by calcium phosphate-DNA precipitate method, NIH3T3 pcDNA3-DAFMCP-DP transfectants were obtained by G418 selection. Extraneous genes integration was identified by PCR. The co-expression of human DAF and MCP at both mRNA and protein levels was confirmed by using RT-PCR and Western blot analysis. Human DAF and MCP cDNA were integrated into NIH3T3 pcDNA3-DAFMCP-DP genomic DNA after continuous 30 times passages, indicating that NIH3T3 pcDNA3-DAFMCP-DP were stable cell lines. Human C-mediated cytolysis assays showed that NIH3T3 cells transfected stably with pcDNA3-DAF, pcDNA3-MCP, and pcDNA3-DAFMCP-DP were protected from C-mediated damage and co-expressed human DAF and MCP provided more excellent protection against C-mediated attack, which was compared with either DAF or MCP alone. These results suggest that the dicistronic vector could improve the efficiency of multi-gene delivery and benefit the synergic effect of human membrane complement regulatory proteins DAF and MCP.

Lymphoma chemovirotherapy: CD20-targeted and convertase-armed measles virus can synergize with fludarabine

Combination chemotherapy regimen incorporating CD20 antibodies are commonly used in the treatment of CD20-positive non-Hodgkin's lymphoma (NHL). Fludarabine phosphate (F-araAMP), cyclophosphamide, and CD20 antibodies (Rituximab) constitute the FCR regimen for treating selected NHL, including aggressive mantle cell lymphoma (MCL). As an alternative to the CD20 antibody, we generated a CD20-targeted measles virus (MV)-based vector. This vector was also armed with the prodrug convertase purine nucleoside phosphorylase (PNP) that locally converts the active metabolite of F-araAMP to a highly diffusible substance capable of efficiently killing bystander cells. We showed in infected cells that early prodrug administration controls vector spread, whereas late administration enhances cell killing. Control of spread by early prodrug administration was also shown in an animal model: F-araAMP protected genetically modified mice susceptible to MV infection from a potentially lethal intracerebral challenge. Enhanced oncolytic potency after extensive infection was shown in a Burkitt's lymphoma xenograft model (Raji cells): After systemic vector inoculation, prodrug administration enhanced the therapeutic effect synergistically. In a MCL xenograft model (Granta 519 cells), intratumoral (i.t.) vector administration alone had high oncolytic efficacy: All mice experienced complete but temporary tumor regression, and survival was two to four times longer than that of untreated mice. Cells from MCL patients were shown to be sensitive to infection. Thus, synergy of F-araAMP with a PNP-armed and CD20-targeted MV was shown in one lymphoma therapy model after systemic vector inoculation.

A capsid-modified, conditionally replicating oncolytic adenovirus vector expressing TRAIL Leads to enhanced cancer cell killing in human glioblastoma models

Glioblastoma multiforme (GBM) is the most aggressive brain tumor, and patients rarely survive for more than 2 years. Gene therapy may offer new treatment options and improve the prognosis for patients with GBM. Adenovirus-mediated gene therapy strategies for brain tumors have been limited by inefficient gene transfer due to low expression of the adenovirus serotype 5 (Ad5) receptor. We have used an adenovirus vector that specifically replicates in tumor cells and uses an Ad5 capsid and the adenovirus serotype (Ad35) fiber for efficient infection of malignant tumor cells. This vector also expresses adenovirus E1A and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in a tumor-specific manner. Here, we show that this oncolytic vector (Ad5/Ad35.IR-E1A/TRAIL) efficiently infects the GBM tumor cell lines SF767, T98G, and U-87 MG. Tumor cell killing was markedly enhanced with Ad5/Ad35.IR-E1A/TRAIL compared with wild-type Ad5 and Ad35 virus or Ad5/Ad35.IR-E1A- vectors without TRAIL expression in vitro. In vivo experiments using s.c. xenografted U-87 MG cells in NOD/SCID mice showed a significant growth delay of tumors after i.t. injection of Ad5/Ad35.IR-E1A/TRAIL, whereas adenovirus wild-type injections showed only marginal or no effect. Our findings indicate that the use of a capsid-modified adenoviral vector, in combination with TRAIL expression, is a promising novel approach for gene therapy of glioblastoma.

Down-regulation of CD55 and CD46 expression by anti-sense phosphorothioate oligonucleotides (S-ODNs) sensitizes tumour cells to complement attack

Overexpression of one or more membrane-bound complement regulatory proteins (mCRPs) protects tumour cells against complement-mediated clearance by the autologous humoral immune response and is also considered as a barrier for successful immunotherapy with monoclonal anti-tumour antibodies. Neutralization of mCRPs by blocking antibodies, enzymatic removal or cytokine-mediated down-regulation has been shown to sensitize tumour cells to complement attack. In our study we applied, for the first time, anti-sense phosphorothioate oligonucleotides (S-ODNs) to knock down the expression of the mCRPs CD55 and CD46 with the aim of exploiting complement more effectively for tumour cell damage. Potent anti-sense oligonucleotides against CD55 and CD46 were identified by screening various target sequences (n = 10) for each regulator. S-ODN anti-CD55(687) reduced CD55 protein expression up to 84% and CD46 protein expression was inhibited up to 76% by S-ODN anti-CD46(85). Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed a similar reduction of the CD55 and CD46 mRNA levels, which argues for an RNAse H-dependent anti-sense mechanism. T47D, A549 and PC3 cells, representing breast, lung and prostate carcinoma, were used for functional studies. Dependent on the particular cell line, anti-sense-based inhibition of mCRP expression enhanced complement-dependent cytolysis (CDC) up to 42% for CD55 and up to 40% for CD46, and the combined inhibition of both regulators yielded further additive effects in T47D cells. C3 opsonization of CD55/CD46-deficient tumour cells was also clearly enhanced upon mCRP suppression. Due to the clinical applicability of S-ODNs, the anti-sense approach described in this study may offer an additional alternative to improve the efficacy of antibody- and complement-based cancer immunotherapy.

A human lung carcinoma cell line supports efficient measles virus growth and syncytium formation via a SLAM- and CD46-independent mechanism

Measles virus (MV) propagates mainly in lymphoid organs throughout the body and produces syncytia by using signaling lymphocyte activation molecule (SLAM) as a receptor. MV also spreads in SLAM-negative epithelial tissues by unknown mechanisms. Ubiquitously expressed CD46 functions as another receptor for vaccine strains of MV but not for wild-type strains. We here show that MV grows and produces syncytia efficiently in a human lung adenocarcinoma cell line via a SLAM- and CD46-independent mechanism using a novel receptor-binding site on the hemagglutinin protein. This infection model could advance our understanding of MV infection of SLAM-negative epithelial cells and tissues.

Adenovirus type 5 substituted with type 11 or 35 fiber structure increases its infectivity to human cells enabling dual gene transfer in CD46-dependent and -independent manners

Infectivity of adenovirus type 5 (Ad5) to cells depends primarily on its fiber-mediated binding to the coxsackievirus and adenovirus receptor (CAR) on target cells. Down-regulated CAR expression, often found in human tumors, hampered Ad5-mediated gene transfer. Ad 11 and Ad 35, belonging to a subtype B group, use CD46 as their cellular receptors; accordingly, chimeric Ad5 whose fiber structure was substituted with that of the type 11 or 35 (Ad5/11 or Ad5/35) could infect human cells in a different manner from Ad5. We found that Ad5/35 infected human tumors, including pancreatic and breast cancer, and human fibroblasts better than Ad5 and Ad5/11. Infectivity of Ad5/35 to these cells was correlated with that of Ad5/11, but efficacy of Ad5/35- and Ad5/11-mediated transduction was not directly correlated with the expression level of CD46 in the target cells. Infection of human hepatoma cells with measles virus, whose cellular receptor is CD46, down-regulated the CD46 expression and reduced subsequent infectivity of Ad5/35 but not Ad5/11. Infection of Ad5 suppressed subsequent gene transfer by Ad5 but not by Ad5/11 orAd5/35. Likewise infection of Ad5/35 decreased following gene transduction by Ad5/35 and Ad5/11, but to a lesser extent by Ad5. These data collectively showed that combinatory use of Ad5 and the chimeric Ad enables dual gene transfer into target cells and suggest that infectivity of subtype B Ad does not completely depend on CD46 expression and that other receptors possibly influence the infectivity.

Engineered measles virus as a novel oncolytic viral therapy system for hepatocellular carcinoma

The oncolytic measles virus Edmonston strain (MV-Edm), a nonpathogenic virus targeting cells expressing abundant CD46, selectively destroys neoplastic tissue. Clinical development of MV-Edm would benefit from noninvasive monitoring strategies to determine the speed and extent of the spread of the virus in treated patients and the location of virus-infected cells. We evaluated recombinant MV-Edm expressing carcinoembryonic antigen (CEA) or the human sodium iodide symporter (hNIS) for oncolytic potential in hepatocellular carcinoma (HCC) and efficiency in tracking viruses in vivo by noninvasive monitoring. CD46 expression in human HCC and primary hepatocytes was assessed by flow cytometry and immunohistochemistry. Infectivity, syncytium formation, and cytotoxicity of recombinant MV-Edm in HCC cell lines were evaluated by fluorescence microscopy, crystal violet staining, and the MTS assay. Transgene expression in HCC cell lines after infection with recombinant MV-Edm in vitro and in vivo was assessed by CEA concentration, 125I-uptake, and 123I-imaging studies. Toxicology studies were performed in Ifnar(KO)xCD46 transgenic mice. The CD46 receptor was highly expressed in HCC compared to nonmalignant hepatic tissue. Recombinant MV-Edm efficiently infected HCC cell lines, resulting in extensive syncytium formation followed by cell death. Transduction of HCC cell lines and subcutaneous HCC xenografts with recombinant MV-Edm resulted in high-level expression of transgenes in vitro and in vivo. MV-Edm was nontoxic in susceptible mice. Intratumoral and intravenous therapy with recombinant MV-Edm resulted in inhibition of tumor growth and prolongation of survival with complete tumor regression in up to one third of animals. In conclusion, engineered MV-Edm may be a potent and novel cancer gene therapy system for HCC. MV-Edm expressing CEA or hNIS elicited oncolytic effects in human HCC cell lines in vitro and in vivo, enabling the spread of the virus to be monitored in a noninvasive manner.

CD46 expression is indicative of shorter revival-free survival for ovarian cancer patients

BACKGROUND

The membrane cofactor protein CD46 represents a complement inhibitor, which protects autologous cells from complement - mediated cytotoxicity. CD46 may exhibit the potential to protect tumor cells from the immune responses of the host. The present study aimed to evaluate the prognostic significance of CD46 expression in ovarian cancers.

MATERIALS AND METHODS

The analyses were performed on 73 ovarian cancer samples. Immunohistochemical reactions were performed on paraffin sections of tumors using monoclonal antibodies directed against CD46. The immunohistochemical reactions and the clinical observations results were subjected to statistical analysis.

RESULTS

Expression of CD46 was demonstrated in 60% of primary laparotomy cases and in 70% secondary cytoreduction cases. Kaplan-Meier analysis showed that a significantly shorter revival-free time was linked to cases with CD46 expression at PL (p= 0.01).

CONCLUSION

Ovarian cancers manifest CD46 expression that is linked to a less favourable prognosis.

Quantitative expression analysis of HHV-6 cell receptor CD46 on cells of human cord blood, peripheral blood and G-CSF mobilised leukapheresis cells

Human herpesvirus-6 (HHV-6) can infect blood cells and thereby may inhibit hematopoietic stem and progenitor cell expansion and differentiation. In this context, it has been discussed if early progenitor cells can be infected by HHV-6. CD46 was identified as one possible cellular surface receptor for HHV-6. The study presented here had been done to get insight into the susceptibility of various leukocyte subpopulations to HHV-6 (including early hematopoietic progenitors) by determining the amount of CD46 molecules expressed on their surfaces. Human cord blood cells, peripheral blood cells and G-CSF mobilised progenitor cells were analysed by flow cytometry. CD46 molecule number per cell was determined and compared to calibration beads conjugated with known ratio of PE per bead. Highest CD46 expression was detected on B- lymphocytes, whereas T-lymphocytes only showed about half of the amount found on B cells. Hematopoietic progenitors also carried CD46 at intermediate levels. Unexpectedly, CD46 expression on progenitors from G-CSF mobilised leukapheresis products was approximately 20% of that found on comparable cells from untreated cord blood. In conclusion, hematopoietic progenitor cells express CD46 on their surface, thereby fulfilling a basic requirement for the susceptibility of HHV-6 infection.

Intradermal Delivery of Adenoviral Type-35 Vectors Leads to High Efficiency Transduction of Mature, CD8+T Cell-Stimulating Skin-Emigrated Dendritic Cells

Recombinant adenovirus (Ad) type 35 (rAd35) shows great promise as vaccine carrier with the advantage of low pre-existing immunity in human populations, in contrast to the more commonly used rAd5 vector. The rAd35 vector uses CD46 as a high-affinity receptor, which, unlike the rAd5 receptor, is expressed on human dendritic cells (DC), the most powerful APCs identified to date. In this study, we show that in contrast to rAd5, rAd35 infects migrated and mature CD83+ cutaneous DC with high efficiency (up to 80%), when delivered intradermally in an established human skin explant model. The high transduction efficiency is in line with high expression levels of CD46 detected on migratory cutaneous DC, which proved to be further increased upon intradermal administration of GM-CSF and IL-4. As compared with Ad5, these Ad35 infection characteristics translate into higher absolute numbers of skin-emigrated DC per explant that both express the transgene and are phenotypically mature. Finally, we demonstrate that upon intracutaneous delivery of a rAd35 vaccine encoding the circumsporozoite (CS) protein of Plasmodium falciparum, emigrated DC functionally express and process CS-derived epitopes and are capable of activating specific CD8+ effector T cells, as evidenced by activation of an HLA-A2-restricted CS-specific CD8+ T cell clone. Collectively, these data demonstrate the utility of rAd35 vectors for efficient in vivo human DC transduction.

Oncolytic measles virus targets high CD46 expression on multiple myeloma cells

OBJECTIVE

Multiple myeloma (MM) is an incurable B cell malignancy and novel therapeutics are urgently needed. Live attenuated measles virus (MV) has potent oncolytic activity against MM tumor xenografts. The virus is tumor selective and preferentially targets cells that express high levels of CD46 receptors. However, CD46 levels on MM have not previously been evaluated. In this study, we investigated the potential of CD46 as a target for MM therapy and correlated surface levels of CD46 on MM cells with their susceptibility to MV-induced cytopathic effects.

MATERIALS AND METHODS

CD46 expression on neoplastic plasma cells (PCs) and nonplasma cells (NPCs) from 38 MM patients was analyzed by flow cytometry and receptor numbers were quantitated using BD QuantiBRITE PE beads.

RESULTS

Results showed that malignant PCs expressed significantly higher levels of CD46 receptors compared to NPCs (p < 0.0001). The mean CD46 receptor numbers on PCs and NPCs were 49,130/cell and 7,340/cell, respectively. Potent cytopathic effects of extensive intercellular fusion were observed in measles-infected PCs but not in NPCs. The extent of MV-induced cytopathic effects of cell fusion correlated with CD46 expression levels on the MM cells. Normal plasma cells do not overexpress CD46 and colony-forming assays demonstrated that MV was not cytotoxic to normal bone marrow progenitor cells.

CONCLUSION

The present study establishes CD46 as a surface antigen that is expressed more abundantly on primary MM cells compared to normal hematopoietic cells of various lineages in the bone marrow, making CD46 a promising surface marker for targeted cytoreductive therapy of MM.

ADAM10-mediated Release of Complement Membrane Cofactor Protein during Apoptosis of Epithelial Cells

Membrane cofactor protein CD46 controls complement activation on cells, is a receptor for several pathogens, and modulates immune responses by affecting CD8(+) T cells. Cells can release CD46 in an intact form on membrane vesicles and in a truncated form by a metalloproteolytic cleavage. The mechanism of shedding and its relationship to cell physiology has remained unclear. We have found using RNA interference analysis that a disintegrin and metalloproteinase (ADAM) 10 is responsible for the regulated shedding of the ectodomain of CD46 in apoptotic cells. The shedding of CD46 was initiated with staurosporine and UVB. Exposure of cell cultures to either UVB or staurosporine resulted in changes of cell morphology and detachment of cells from their matrices within 8-24 h. During this process CD46 was released both in apoptotic vesicles (vCD46) and proteolytically (sCD46) into the medium. Both the metalloproteinase inhibitor GM6001 and RNA interference of ADAM10 completely prevented the release of sCD46 and increased the expression of vCD46 on HaCaT cell vesicles, suggesting that ADAM10 releases sCD46 from the apoptotic vesicles. To explore whether the release of sCD46 is associated with apoptosis we analyzed the effects of caspase inhibitors. As expected, the inhibition of caspase activity attenuated the characteristic features of apoptosis and also decreased the release of sCD46. Our results reveal ADAM10 as an important regulator of CD46 expression during apoptosis. The ADAM10-mediated release of CD46 from apoptotic vesicles may represent a form of strategy to allow restricted complement activation to deal with modified self.

Genetics of HUS: the impact of MCP, CFH, and IF mutations on clinical presentation, response to treatment, and outcome

Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy with manifestations of hemolytic anemia, thrombocytopenia, and renal impairment. Genetic studies have shown that mutations in complement regulatory proteins predispose to non-Shiga toxin-associated HUS (non-Stx-HUS). We undertook genetic analysis on membrane cofactor protein (MCP), complement factor H (CFH), and factor I (IF) in 156 patients with non-Stx-HUS. Fourteen, 11, and 5 new mutational events were found in MCP, CFH, and IF, respectively. Mutation frequencies were 12.8%, 30.1%, and 4.5% for MCP, CFH, and IF, respectively. MCP mutations resulted in either reduced protein expression or impaired C3b binding capability. MCP-mutated patients had a better prognosis than CFH-mutated and nonmutated patients. In MCP-mutated patients, plasma treatment did not impact the outcome significantly: remission was achieved in around 90% of both plasma-treated and plasma-untreated acute episodes. Kidney transplantation outcome was favorable in patients with MCP mutations, whereas the outcome was poor in patients with CFH and IF mutations due to disease recurrence. This study documents that the presentation, the response to therapy, and the outcome of the disease are influenced by the genotype. Hopefully this will translate into improved management and therapy of patients and will provide the way to design tailored treatments.

Complement Activated by Chimeric Anti–Folate Receptor Antibodies Is an Efficient Effector System to Control Ovarian Carcinoma

Two chimeric monoclonal antibodies (mAb), cMOV18 and cMOV19, recognizing distinct epitopes of folate receptor highly expressed on epithelial ovarian cancer (EOC) cells were analyzed for their ability to activate complement (C) as a means to enhance their antitumor activity. The individual cMOVs failed to activate C on six EOC cell lines as documented by the marginal deposition of C components and the negligible C-dependent cytotoxicity (CDC). Conversely, the mixture of cMOVs was more effective, although the percentage of cell killing did not exceed 25%. Fluorescence-activated cell sorting analysis of EOC cells for surface expression of the membrane C regulatory proteins (mCRP) revealed high levels of CD46, variable expression of CD59, and absence of CD55. This finding was confirmed in tumor tissue specimens obtained from advanced-stage EOC patients and analyzed for the expression of mCRPs mRNA using a cDNA microarray and for the presence of proteins by immunohistochemistry. Incubation of EOC cells with neutralizing mAbs to CD46 and CD59 led to a significant increase in the CDC from 10%-20% to 45%-50%. The relative contribution of antibody-dependent cell cytoxicity (ADCC) and C-dependent killing of two EOC cell lines induced by the mixture of cMOV18 and cMOV19 was about 15% and 25%-35%, respectively, bringing the total killing to about 40%-50%. This value increased to 60%-70% after neutralization of CD46 and CD59 without an appreciable change of ADCC. These results suggest that C is the major contributor to the killing of EOC cells induced by the mixture of cMOV18 and cMOV19.

Analysis of membrane-bound complement regulatory proteins in prostate cancer

OBJECTIVES

Membrane-bound complement regulatory proteins (mCRPs) are ubiquitously expressed throughout the cells of the hematopoietic system and protect host cells from complement-mediated lysis. The expression and functionality of mCRPs have been demonstrated in several types of cancers; however, no clear correlation has been appreciated between tumor stage and mCRP expression.

METHODS

We investigated the expression pattern of CD46, CD55, CD59, and CD97 (a receptor for CD55) in prostate cancer by tissue microarray analysis using high-density tissue microarrays spotted with tissue cores from biopsy and autopsy specimens. Real-time polymerase chain reaction was used to confirm the tissue microarray data by quantifying mRNA expression in clinically identified tissue specimens.

RESULTS

CD55 and CD97 demonstrated increased expression in prostatic intraepithelial neoplasia, localized prostate cancer, and metastatic prostate cancer specimens compared with normal tissue specimens. No appreciable difference was seen in CD46 or CD59 expression. These data were confirmed by real-time polymerase chain reaction of mRNA expression levels in grossly identified specimens.

CONCLUSIONS

These data suggest that mCRPs are differentially expressed in prostate cancer, with CD55 the predominant mCRP upregulated in malignant prostate epithelial cells. Additionally, CD97 expression correlated with the malignant phenotype and may contribute to the tumorigenic and metastatic potential of prostate cancer.

[Coexpression of human complement regulatory protein genes, CD59 and MCP in transgenic mice protects isolated mouse heart function in ex vivo human plasma perfusion model]

OBJECTIVE

To investigate if the expression of human complement regulatory protein genes in transgenic donor protects against hyperacute rejection (HAR) in the recipient.

METHODS

Kunming mice were transfected with 2 human complement regulatory protein genes, CD59 and MCP, so as to establish a transgenic hCD59/hMCP mouse model. Eight hCD59 expression mice, 11 hMCP expression mice, and 8 hCD59/hMCP expression mice were used as experimental groups, and 10 transgenic negative littermates were used as control group. The hearts of the mice were taken out to be perfused with 10% pooled human blood of B type. During the perfusion electrocardiography was carried out to observe the beating time. After the hearts stopped beating, immunofluorescence staining and immunohistochemistry were used to detect the deposition of complements C(9) and C(3c) in the heart tissue.

RESULTS

The mean heart beating time was 138 +/- 25 minutes in the hCD59/hMCP expression group, 78 +/- 27 minutes in the hCD59 expression group, 43 +/- 21 minutes in the hMCP group, and 20 +/- 12 minutes in the wild type nontransgenic control group (all P < 0.01, Dennett's T test for all 3 other groups relative to the hCD59/hMCP group). Deposition of the complement C(9) and that of C(3c) were not found in the hearts of the hCD59/hMCP group, however, could be found in the hearts of the 2 monotransgenic groups and nontransgenic group.

CONCLUSION

The coexpression of human complement regulatory protein genes, CD59 and MCP in the xenografts effectively inhibits the complement of xenograft-mediated HAR.

A novel type of detergent-resistant membranes may contribute to an early protein sorting event in epithelial cells

One sorting mechanism of apical and basolateral proteins in epithelial cells is based on their solubility profiles with Triton X-100. Nevertheless, apical proteins themselves are also segregated beyond the trans-Golgi network by virtue of their association or nonassociation with cholesterol/sphingolipid-rich microdomains (Jacob, R., and Naim, H. Y. (2001) Curr. Biol. 11, 1444-1450). Therefore, extractability with Triton X-100 does not constitute an absolute criterion of protein sorting. Here, we investigate the solubility patterns of apical and basolateral proteins with other detergents and demonstrate that the mild detergent Tween 20 is adequate to discriminate between apical and basolateral proteins during early stages in their biosynthesis. Although the mannose-rich forms of the apical proteins sucrase-isomaltase, lactase-phlorizin hydrolase, aminopeptidase N, and dipeptidylpeptidase IV reveal similar solubility profiles comprising soluble and nonsoluble fractions, the basolateral proteins, vesicular stomatitis virus G protein, major histocompatibility complex class I, and CD46 are entirely soluble with this detergent. The insoluble Tween 20 membranes are enriched in phosphatidylinositol and phosphatidylglycerol compatible with their synthesis in the endoplasmic reticulum and the existence of a novel class of detergent-resistant membranes. The association of the mannose-rich biosynthetic forms of the apical proteins, sucraseisomaltase, lactase-phlorizin hydrolase, aminopeptidase N, and dipeptidylpeptidase IV with the Tween 20-resistant membranes suggests an early polarized sorting mechanism prior to maturation in the Golgi apparatus.

CD46 Plays a Key Role in Tailoring Innate Immune Recognition of Apoptotic and Necrotic Cells

Complement is the canonical innate immune system involved in host defense and tissue repair with the clearance of cell debris. In contrast to the robust armory mounted against microbial nonself-pathogens, complement is selectively activated on altered self (i.e. apoptotic and necrotic cells) to instruct the safe demise by poorly characterized mechanisms. Our data shed new light on the role of complement C1q in sensing nucleic acids (NA) rapidly exposed on apoptotic Jurkat T cell membranes and in driving C3 opsonization but without the lytic membrane attack complex. DNA/RNase-treated apoptotic cells failed to activate complement. We found that several other apoptotic cell models, including senescent keratinocytes, ionophore-treated sperm cells, and CMK-derived platelets, stained for cleaved caspase 3 were rapidly losing the key complement regulator CD46. CD46 from nuclear and membrane stores was found to cluster into blebs and shed into microparticles together with NA, phosphatidylserine, C1q, and factor H. Classical and alternative pathways of complement were involved in the recognition of H2O2-treated necrotic cells. Membrane attack complex was detected on necrotic cells possibly as a result of CD46 and CD59 shedding into soluble forms. Our data highlight a novel and universal paradigm whereby the complement innate immune system is using two synergistic strategies with the recognition of altered self-NA and missing self-CD46 signals to instruct and tailor the efficient removal of apoptotic and necrotic cells in immunoprivileged sites.

Increased infectivity of adenovirus type 5 bearing type 11 or type 35 fibers to human esophageal and oral carcinoma cells

Esophageal and oral carcinomas are relatively resistant to adenovirus serotype 5 (Ad5)-mediated gene transfer, primarily because expression of the cellular receptors for Ad5, the coxsackievirus and adenovirus receptor, is often downregulated in these types of tumor. The types of Ad in which the receptor expression is not suppressed in tumors are therefore better vectors for gene transfer into tumors. CD46, a cellular receptor for Ad subtype B2, such as Ad11 and Ad35, is well expressed in a number of esophageal and oral tumor cells. Since the infectivity of Ad to target cells is mainly influenced by the interaction between their fibers and the cellular receptors, we examined the infectivity of chimeric Ad5, whose fiber structure was substituted with that of type 11 or 35 (Ad5/11 or Ad5/35), to 6 human oral and 11 esophagus carcinoma cells. We found that the chimeric Ad, in particular Ad5/35, infected more effectively than Ad5 in all the tumors tested. However, the efficacy of Ad5/35- and Ad5/11-mediated transduction was not correlated with the expression level of CD46 or CD80/86, a cellular receptor of the Ad subtype B1, in the target cells. These data suggest that the Ad subtype B2 are suitable vectors of gene transfer for human squamous cell carcinomas of the upper gastrointestinal tract, and that the infectivity of the Ad subtype B2 can possibly be regulated by other receptors besides CD46.

Helicobacter pylori eradication decreases the expression of glycosylphosphatidylinositol-anchored complement regulators, decay-accelerating factor and homologous restriction factor 20, in human gastric epithelium

BACKGROUND

It has previously been reported that there is a strong correlation between the expression of glycosylphosphatidylinositol (GPI)-anchored complement membrane inhibitor in gastric epithelium and the severity of inflammation of gastric mucosa. To investigate the regulation of complement activity in gastric epithelium during Helicobacter pylori (H. pylori)-associated gastritis, the expression of GPI-anchored complement membrane inhibitors, decay-accelerating factor (DAF) and 20-kDa homologous restriction factor 20 (HRF20), and membrane cofactor protein (MCP), which is a transmembrane protein, were evaluated after removal of the H. pylori stimulus. Furthermore, the expression of the complement fragment, C3c, was also investigated.

METHODS

Forty-six patients with epigastric symptoms and endoscopically confirmed peptic ulcer or gastritis who had H. pylori infection of the gastric mucosa were enrolled in the present study. Biopsy specimens were obtained from the gastric antrum and corpus 1 month before and after eradication. Helicobacter pylori infection was determined by the rapid urease test, histology, and culture before eradication, and by histology, culture, and urea breath test after eradication. Gastric biopsy specimens obtained before and after eradication were evaluated for infiltration by neutrophils and mononuclear cells. The expression of complement membrane inhibitors, DAF, HRF20, and MCP and that of the main complement fragment, C3c, was immunohistochemically evaluated.

RESULTS

One month after the eradication of H. pylori, the infiltration by neutrophils and mononuclear cells in the gastric mucosa decreased significantly (P < 0.0001) as compared with that before eradication. The expression of DAF, HRF20, and C3c on gastric mucosal epithelium also significantly decreased in both the antrum and the corpus (P < 0.05) 1 month after eradication. However, no change was observed in the expression of MCP.

CONCLUSIONS

The decrease in the expression of GPI-anchored complement regulator and the complement after removal of a chronic microbial stimulus suggests that the gastric epithelium appears to undergo an aggressive stress of complement during H. pylori infection. Conclusively, DAF and HRF20 may play an important protective role against complement-mediated damage induced by chronic microbial stimuli in such a pathological condition.

Phosphatidylserine externalization in human sperm induced by calcium ionophore A23187: relationship with apoptosis, membrane scrambling and the acrosome reaction

BACKGROUND

Translocation of phosphatidylserine (PS) from the inner to the outer leaflet of the plasma membrane is a modification of the lipid architecture occurring in sperm. This is one of the earliest signs of apoptosis that can be monitored by the calcium-dependent binding of annexin V.

METHODS AND RESULTS

Flow cytometric analysis of annexin V binding was performed. Calcium ionophore A23187 led to a significant increase in the proportion of living sperm with PS exposure: 7.3 3.2% of cells in the untreated ejaculate versus 47.5 5.6% of cells after 1 h of incubation with A23187. Conversely, diminution of mitochondrial membrane potential [DiOC6(3)/propidium iodide (PI) assay], caspase activation [fluorescein isothiocyanate (FITC)-Val-Ala-Asp-fluoromethylketone (VAD-FMK)/PI assay], increased plasma membrane permeability (Yo-Pro-1/PI assay) and increased DNA fragmentation [TdT (terminal deoxynucleotidyl transferase)-mediated dUDP nick-end labelling assay], which are among the main signs of apoptosis, were not observed in sperm, even after 4 h of incubation with A23187. However, A23187 significantly increased the proportion of sperm with plasma membrane scrambling and with a reacted acrosome, as detected with the merocyanine 540 probe (M540) and the monoclonal anti-human CD46-PE antibody respectively.

CONCLUSIONS

Our results suggest that PS exposure in human sperm, as induced by A23187, is mainly related to the acrosome reaction rather than to apoptosis.

Engagement of CD46 and α5β1 integrin by group A streptococci is required for efficient invasion of epithelial cells

Membrane cofactor protein (MCP or CD46), a widely distributed complement regulatory human protein, is a cell surface receptor for many pathogens including group A streptococci (GAS). The surface M protein of GAS binds CD46 and mediates GAS adherence to keratinocytes. In the present study, we studied the role of CD46 in GAS invasion of human lung epithelial cells, A549. Anti-CD46 antibody which specifically blocks the domain to which M protein binds inhibited adherence to and invasion of A549 cells by GAS. Moreover, downregulation of CD46 expression on A549 by RNA interference resulted in reduced invasion of these cells by GAS. A mutant form of CD46 with a deletion in the cytoplasmic domain was overexpressed in A549 cells, which resulted in partial inhibition of invasion. This indicates that the cytoplasmic tail is required for CD46 to promote invasion by GAS. Invasion assays with Lactococcus lactis that express M protein demonstrated the dependence of CD46-promoted invasion on interaction with M protein. In addition, CD46-mediated invasion was also found to be dependent on the extracellular matrix protein fibronectin.