Intramuscular DNA vaccination protocols mediated by electric fields

Vaccination is historically one of the most important methods for preventing infectious diseases in humans and animals. New insights in the biology of the immune system allow a more rational design of vaccines, and new vaccination strategies are emerging. DNA vaccines have been proposed as a promising approach for introducing foreign antigens into the host for inducing protective immunity against infectious and cancer diseases. Nevertheless, because of their poor immunogenicity, plasmid DNA vaccination strategies need further implementations. Recent data suggest electrotransfer as a useful tool to improve DNA-based vaccination protocols, being able to stimulate both the humoral and cellular immune responses. In preclinical trials, gene electrotransfer is successfully used in prime-boost combination protocols and its tolerability and safety has been demonstrated also in Phase I clinical trials. In this chapter, we report a short comment supporting electrotransfer as an effective strategy to improve DNA-based vaccination protocols and describe the vaccination procedures by plasmid DNA in combination with electrotransfer and hyaluronidase pretreatment in use in our laboratory.

The fragile X protein binds mRNAs involved in cancer progression and modulates metastasis formation

The role of the fragile X mental retardation protein (FMRP) is well established in brain, where its absence leads to the fragile X syndrome (FXS). FMRP is almost ubiquitously expressed, suggesting that, in addition to its effects in brain, it may have fundamental roles in other organs. There is evidence that FMRP expression can be linked to cancer. FMR1 mRNA, encoding FMRP, is overexpressed in hepatocellular carcinoma cells. A decreased risk of cancer has been reported in patients with FXS while a patient-case with FXS showed an unusual decrease of tumour brain invasiveness. However, a role for FMRP in regulating cancer biology, if any, remains unknown. We show here that FMRP and FMR1 mRNA levels correlate with prognostic indicators of aggressive breast cancer, lung metastases probability and triple negative breast cancer (TNBC). We establish that FMRP overexpression in murine breast primary tumours enhances lung metastasis while its reduction has the opposite effect regulating cell spreading and invasion. FMRP binds mRNAs involved in epithelial mesenchymal transition (EMT) and invasion including E-cadherin and Vimentin mRNAs, hallmarks of EMT and cancer progression.

Hyaluronidase contributes to early inflammatory events induced by electrotransfer in mouse skeletal muscle

Electrotransfer of genes is one of the preferred strategies used to deliver plasmid DNA into skeletal muscle. In our experience, the combination of hyaluronidase (HYA) with electrotransfer (ET) of DNA vaccine enhances transfection of muscular fibers and increases expression of the encoded antigen. However, the contribution of HYA to the inflammatory reaction induced by ET, and its role in supporting ET adjuvancy, has never been investigated. We analyzed the events occurring in the first 2 weeks after electrotransfer to mouse muscle in the presence of HYA, to verify whether HYA contributes to the local inflammatory response induced by ET. Our results demonstrate that HYA amplifies the ET effect in terms of inflammatory cell recruitment enhancing the early release of interleukin (IL)-1β, tumor necrosis factor-α, and IL-6 cytokines. In contrast, HYA does not induce helper T cell type 1 and 2 cytokine production, confirming that the DNA vaccine is indispensable to induce mediators of antigen-specific immune responses. We observed inflammatory cell migration in the muscle treated with HYA plus ET in a time window between days 4 and 7 after cytokine induction. These observations are important in the choice of prime-boost intervals for optimizing ET-based DNA vaccination protocols. Because HYA contributes to vaccine spread and enhances the proinflammatory effect of ET in muscle we strongly support the use of HYA to potentiate DNA vaccine efficacy.

BCR/ABL1 fusion transcripts generated from alternative splicing: implications for future targeted therapies in Ph+ leukaemias

Philadelphia (Ph+) positive leukaemias are an example of haematological malignant diseases where different chromosomal rearrangements involving both BCR and ABL1 genes generate a variety of chimeric proteins (BCR/ABL1 p210, p190 and p230) which are considered pathological "biomarkers". In addition to these three, there is a variety of fusion transcripts whose origin may depend either on diverse genetic rearrangement or on alternative/atypical splicing of the main mRNAs or on the occurrence of single-point mutations. Although the therapy of Ph+ leukaemias based on Imatinib represents a triumph of medicine, not all patients benefit from such drug and may show resistance and intolerance. Furthermore, interruption of Imatinib administration is often followed by clinical relapse, suggesting a failure in the eradication of residual leukaemic stem cells. Therefore, while the targeted therapy is searching for new and implemented pharmacological inhibitors covering all the possible mutations in the kinase domain, there is urge to identify alternative molecular targets to develop other specific and effective therapeutic approaches. In this review we discuss the importance of recent advances based on the discovery of novel BCR/ABL1 variants and their potential role as new targets/biomarkers of Ph+ leukaemias in the light of the current therapeutic trends. The limits of the pharmacological inhibitors used for treating the disease can be overcome by considering other targets than the kinase enzyme. Our evaluations highlight the potential of alternative perspectives in the therapy of Ph+ leukaemias.

Evaluation of antigen specific recognition and cell mediated cytotoxicity by a modified lysispot assay in a rat colon carcinoma model

Background

Antigen-specific CD8+ cytotoxic T lymphocytes represent potent effector cells of the adaptive immune response against viruses as well as tumours. Therefore assays capable at exploring the generation and function of cytotoxic T lymphocytes represent an important objective for both clinical and experimental settings.

Methods

Here we show a simple and reproducible assay for the evaluation of antigen-specific CD8+ cytotoxic T lymphocytes based on a LysiSpot technique for the simultaneous determination of antigen-specific IFN-γ production and assessment of tumor cytolysis. The assay was developed within an experimental model of colorectal carcinoma, induced by the colorectal tumor cell line DHD-K12 that induces tumors in BDIX rats and, in turn, elicits a tumor- specific immune response.

Results

Using DHD-K12 cells transfected to express Escherichia coli β-galactosidase as target cells, and by the fine setting of spot colours detection, we have developed an in vitro assay that allows the recognition of cytotoxic T lymphocytes induced in BDIX rats as well as the assessment of anti-tumour cytotoxicity. The method highlighted that in the present experimental model the tumour antigen-specific immune response was bound to killing target cells in the proportion of 55%, while 45% of activated cells were not cytotoxic but released IFN-γ. Moreover in this model by an ELISPOT assay we demonstrated the specific recognition of a nonapeptide epitope called CSH-275 constitutionally express in DHD-K12 cells.

Conclusions

The assay proved to be highly sensitive and specific, detecting even low frequencies of cytotoxic/activated cells and providing the evaluation of cytokine-expressing T cells as well as the extent of cytotoxicity against the target cells as independent functions. This assay may represent an important tool to be adopted in experimental settings including the development of vaccines or immune therapeutic strategies

The AOM/DSS murine model for the study of colon carcinogenesis: From pathways to diagnosis and therapy studies

Colorectal cancer (CRC) is a major health problem in industrialized countries. Although inflammation-linked carcinogenesis is a well accepted concept and is often observed within the gastrointestinal tract, the underlying mechanisms remain to be elucidated. Inflammation can indeed provide initiating and promoting stimuli and mediators, generating a tumour-prone microenvironment. Many murine models of sporadic and inflammation-related colon carcinogenesis have been developed in the last decade, including chemically induced CRC models, genetically engineered mouse models, and xenoplants. Among the chemically induced CRC models, the combination of a single hit of azoxymethane (AOM) with 1 week exposure to the inflammatory agent dextran sodium sulphate (DSS) in rodents has proven to dramatically shorten the latency time for induction of CRC and to rapidly recapitulate the aberrant crypt foci–adenoma–carcinoma sequence that occurs in human CRC. Because of its high reproducibility and potency, as well as the simple and affordable mode of application, the AOM/DSS has become an outstanding model for studying colon carcinogenesis and a powerful platform for chemopreventive intervention studies. In this article we highlight the histopathological and molecular features and describe the principal genetic and epigenetic alterations and inflammatory pathways involved in carcinogenesis in AOM/DSS–treated mice; we also present a general overview of recent experimental applications and preclinical testing of novel therapeutics in the AOM/DSS model.

Application of electroporation in DNA vaccination protocols

Vaccination is historically one of the most important methods for preventing infectious diseases in humans and animals. Due to recent advances in understanding the biology of the immune system, a more rational design of vaccines and vaccination strategies such as those based on gene transfer have been proposed. In particular, naked DNA vaccination is emerging as a promising approach for introducing foreign antigens into the host, inducing protective immunity against infectious diseases and malignant tumours. Plasmid DNA vaccines offer several advantages in comparison to traditional vaccines such as safety, tolerability and feasibility in manufacture. Nevertheless, because of their poor immunogenicity, plasmid DNA vaccines need further implementation. Recent data suggest electroporation as useful strategy to improve DNA-based vaccination protocols, being able to stimulate both the humoural and cellular immune responses. In pre-clinical trials, electroporation is successfully used in prime-boost combination protocols and its efficacy and tolerability has been demonstrated in Phase I clinical trials. Since these initial results appear promising, in the next future we will assist to further developments of naked DNA vaccination associated to the electroporation technology. This approach not only provides the basis for human studies but also a practical application to veterinary medicine.

DNA vaccination strategies for anti-tumour effective gene therapy protocols

After more than 15 years of experimentation, DNA vaccines have become a promising perspective for tumour diseases, and animal models are widely used to study the biological features of human cancer progression and to test the efficacy of vaccination protocols. In recent years, immunisation with naked plasmid DNA encoding tumour-associated antigens or tumour-specific antigens has revealed a number of advantages: antigen-specific DNA vaccination stimulates both cellular and humoral immune responses; multiple or multi-gene vectors encoding several antigens/determinants and immune-modulatory molecules can be delivered as single administration; DNA vaccination does not induce autoimmune disease in normal animals; DNA vaccines based on plasmid vectors can be produced and tested rapidly and economically. However, DNA vaccines have shown low immunogenicity when tested in human clinical trials, and compared with traditional vaccines, they induce weak immune responses. Therefore, the improvement of vaccine efficacy has become a critical goal in the development of effective DNA vaccination protocols for anti-tumour therapy. Several strategies are taken into account for improving the DNA vaccination efficacy, such as antigen optimisation, use of adjuvants and delivery systems like electroporation, co-expression of cytokines and co-stimulatory molecules in the same vector, different vaccination protocols. In this review we discuss how the combination of these approaches may contribute to the development of more effective DNA vaccination protocols for the therapy of lymphoma in a mouse model.

Increased spermine oxidase (SMO) activity as a novel differentiation marker of myogenic C2C12 cells

Spermine oxidase (SMO) is a FAD-containing enzyme involved in animal cell polyamines (PA) homeostasis, selectively active on spermine and producing H(2)O(2), spermidine, and the 3-aminopropanal. In the present study, we have examined the SMO gene expression during the mouse myoblast C2C12 cell differentiation induced with two different stimuli by RT-PCR analysis, polysome-mRNP distribution and enzyme activity. SMO transcript accumulation and enzymatic activity increases during C2C12 cell differentiation and correlates with the decrease of spermine content. Many proteins are highly regulated during the phenotypic conversion of rapidly dividing C2C12 myoblasts into fully differentiated post-mitotic myotubes. The SMO gene induction represents a novel and additional marker of C2C12 cell differentiation. The sub-cellular localization of the SMOalpha and SMOmu splice variants is not involved in the differentiation processes. Nuclear localization of only the SMOmu protein was confirmed.

Strategies for effective naked-DNA vaccination against infectious diseases

To date, vaccination is an active area of investigation for its application to a great variety of human diseases including infections and cancer. In particular, naked-DNA vaccination has arisen as effective strategy in the preventive medicine field with promising future prospects. The ability of plasmid DNA to activate the humoural and the cellular arms of the immune system against the encoded antigen have resulted in intensive study of new strategies aimed at increasing the DNA vaccine immunogenicity. Nevertheless, plasmid-based vaccines emerged as a safer and advantageous alternative with respect to viral vector vaccines. Recent advances in both the immunological and biotechnological research field made it possible to enhance significantly the DNA vaccine potency. Most of these approaches are based on both the discovery of novel delivery systems and the implementation of plasmid constructs, achieved through genetic engineering. In this review, we will describe some of the most relevant patents issued in the last ten years, supporting the progress made in naked-DNA vaccination against infectious diseases.

A combined analytical approach reveals novel EXT1/2 gene mutations in a large cohort of Italian multiple osteochondromas patients

Multiple osteochondromas (MO), also known as hereditary multiple exostoses (HME), is one of the most common hereditary musculoskeletal diseases in Caucasians (1/50,000) with wide clinical variability and genetic heterogeneity. Two genes have thus far been identified as causing the disease, namely EXT1 and EXT2. Various methods to detect mutations in the EXT genes have been used. Here a cohort of 100 MO patients belonging to unrelated Italian families have been analyzed by single-strand conformation polymorphism (SSCP) analysis or by denaturing high performance liquid chromatography (DHPLC). However, neither of these techniques can detect deletions or duplications of entire exons. Families that were negative at SSCP/DHPLC analysis underwent two-color multiple ligation-dependent probe amplification (MLPA) analysis. By these complementary techniques mutation detection was significantly improved and 26 novel mutations have been revealed as well as 18 previously described mutations to give a total of 44 different mutations. Thus we can conclude that combining MLPA with DHPLC in point-mutations negative MO families, the detection of mutations in EXT genes can significantly improve the identification of both point-mutations and mid-size rearrangements. More important, we were able to characterize all those patients who were negative at the first PCR-based method screening.

Genomic instability and increased expression of BUB1B and MAD2L1 genes in ductal breast carcinoma

In a series of invasive ductal breast carcinoma, we investigated the status of chromosomal and intrachromosomal instability by fluorescence in situ hybridisation and determined the level of mRNA expression for two genes involved in the mitotic spindle checkpoint pathway, BUB1B and MAD2L1. All breast cancers demonstrated higher chromosomal instability rates in tumor samples (average: 56.86%, range: 36.24-76.78%) than in controls (average: 11.54%, range: 9.91-14.84%) (P<0.0001). As well as intrachromosomal instability rates were elevated in tumor (average: 18.45% range: 8.34-35.8%) as compared with controls (average: 4.18% range: 3.47-4.81%) (P<0.0001). An increase in BUB1B and MAD2L1 transcripts was demonstrated in the majority of the tumor tested. BUB1B mRNA levels but not MAD2L1 levels correlated with intrachromosomal instability (r=0.722, P=0.018).

ApoE gene delivery inhibits severe hypercholesterolemia in newborn ApoE-KO mice

Apolipoprotein E, a key regulator in cholesterol-rich lipoprotein metabolism, is considered a strong candidate for treating hypercholesterolemia and cardiovascular disease. Inherited deficiency of this protein results in type III hyperlipoproteinemia in humans. ApoE-knockout mice, which develop spontaneous hypercholesterolemia, are an excellent model of human atherosclerosis. Here we investigated the therapeutic effects of a plasmid vector encoding human APOE3 sequence intramuscularly injected in hypercholesterolemic newborn mice at the ages of 5 and 14 days. We further explored the possibility of inducing tolerance in newborns when injected early. Our data show that direct i.m. naked DNA injection reduces severe hypercholesterolemia in newborn mice. Moreover, when naked DNA is administrated early, no immune response is generated against the human APOE, allowing repeated administrations. Neonatal therapies are important for the treatment of many genetic childhood diseases where early administration is required to prevent developmental damage. We propose the use of direct i.m. naked gene transfer in newborns to prevent long-term damages arising from hypercholesterolemic conditions.

Alternative BCR/ABL splice variants in Philadelphia chromosome-positive leukemias result in novel tumor-specific fusion proteins that may represent potential targets for immunotherapy approaches

Imatinib currently represents the standard treatment in the early chronic phase of chronic myelogenous leukemia (CML), thanks to the high percentage of cytogenetic complete remission achieved, but it is yet unclear to what extent it can eradicate leukemia. Therefore, different vaccination strategies have been suggested, mainly based on the exploitment of the junctional peptides spanning the fusion region of the Bcr/Abl proteins. To identify new potential immunologic targets, 63 Philadelphia chromosome-positive patients and 6 BCR/ABL-positive cell lines were tested in nested reverse transcriptase PCR to detect the presence of BCR/ABL transcripts arising from the alternative splicing of the main BCR/ABL transcripts. We could detect BCR/ABL transcripts with junctions between BCR exon 1, 13, or 14 and ABL exon 4 in approximately 80% of patients and 84% of cell lines, beside the main fusion transcripts. Translation products of these transcripts were characterized at their COOH terminus by a large amino acid portion derived from the out of frame (OOF) reading of ABL gene. These proteins were detected in BCR/ABL-positive cell lines by immunoprecipitation and immunohistochemistry. Finally, we determined whether OOF-specific CD8+ T cells could be found in the peripheral blood of CML patients and whether they could acquire effector function following in vitro sensitization with OOF-derived peptides predicted to bind to human leucocyte antigen (HLA)-A2 and HLA-A3 molecules. We detected the presence of OOF-specific CD8+ T cells in four of four patients studied, and in one case, these T cells exhibited specific cytotoxic activity against both peptide-pulsed targets and autologous primary CML cells.

[Identification of candidate genes and expression profiles, as doping biomarkers]

Administration of prohibited substances to enhance athletic performance represents an emerging medical, social, ethical and legal issue. Traditional controls are based on direct detection of substances or their catabolites. However out-of-competition doping may not be easily revealed by standard analytical methods. Alternative indirect control strategies are based on the evaluation of mid- and long-term effects of doping in tissues. Drug-induced long-lasting changes of gene expression may be taken as effective indicators of doping exposure. To validate this approach, we used real-time PCR to monitor the expression pattern of selected genes in human haematopoietic cells exposed to nandrolone, insulin-like growth factor I (IGF-I) or growth hormone (GH). Some candidate genes were found significantly and consistently modulated by treatments. Nandrolone up-regulated AR, ESR2 and PGR in K562 cells, and SRD5A1, PPARA and JAK2 in Jurkat cells; IGF-I up-regulated EPOR and PGR in HL60 cells, and SRD5A1 in Jurkat; GH up-regulated SRD5A1 and GHR in K562. GATA1 expression was down-regulated in IGF-1-treated HL60, ESR2 was down-regulated in nandrolone-treated Jurkat, and AR and PGR were down-regulated in GH-treated Jurkat. This pilot study shows the potential of molecular biology-based strategies in anti-doping controls.

Lack of association between genetic variants in the mannose-binding lectin 2 (MBL2) gene and HPV infection

Genetic variants in the immunomodulatory gene mannose-binding lectin 2 (MBL2), were associated with risk, severity, and frequency of viral infections. In a case-control setting, we investigated the association of MBL2 functional polymorphisms with Human Papillomas Virus (HPV) infection. No differences between cases (HPV(+)) and controls (HPV(-)) were found in the distribution of each single genotypes or allele. Haplotype analysis did not show any difference between HPV+ and HPV(-) groups.

Simple and effective determination of apolipoprotein E genotypes by positive/negative polymerase chain reaction products

Several protein and DNA-based methods have been previously described for the identification of apolipoprotein E isoforms or genotypes. However, all of them generate frequently false-positive results. The purpose of this study was to set up a new, simple, and effective method for the analysis of the apoE polymorphism. A total of 1,253 subjects previously examined for the apolipoprotein E polymorphism by restriction fragment length polymorphism were reanalyzed by our new method based on Taq DNA polymerase's inability to correctly initiate the replication in the presence of a mismatch at the 3' end of the primer. We conceived a combination of 4 specific primers in 3 different pairs sharing the same stringent polymerase chain reaction conditions to directly detect the presence/absence of polymerase chain reaction products, and thus reveal the 6 apolipoprotein E genotypes. We confirm our previous results in 1,171 subjects, whereas in 82 subjects out of 1,253 (about 6%), the results have been reinterpreted. The final analysis revealed a total of 12 homozygotic subjects for the e2 allele (1.0%), 874 homozygotes for the e3 allele (69.8 %), and 8 homozygotes for the e4 allele (0.6 %). The frequence of heterozygotes was 8.7% for the e2/e3 genotype (n=109), 1.4% for the e2/e4 genotype (n=17), and 0.6% for the e3/e4 genotype (n=8). Relative allele frequencies were e2=0.060, e3=0.834, and e4=0.106. We describe a new, simple, unequivocal, and nonexpensive method for the identification of the 6 apoE genotypes.