704/DNA vaccines leverage cytoplasmic DNA stimulation to promote anti-HIV neutralizing antibody production in mice and strong immune response against alpha-fetoprotein in non-human primates

Genetic immunization is an attractive approach for prophylactic and therapeutic vaccination using synthetic vectors to deliver antigen-encoding nucleic acids. Recently, DNA delivered by a physical means or RNA by liposomes consisting of four different lipids demonstrated good protection in human phase III clinical trials and received Drugs Controller General of India and US FDA approval to protect against COVID-19, respectively. However, the development of a system allowing for efficient and simple delivery of nucleic acids while improving immune response priming has the potential to unleash the full therapeutic potential of genetic immunization. DNA-based gene therapies and vaccines have the potential for rapid development, as exemplified by the recent approval of Collategene, a gene therapy to treat human critical limb ischemia, and ZyCoV, a DNA vaccine delivered by spring-powered jet injector to protect against SARS-CoV2 infection. Recently, we reported amphiphilic block copolymer 704 as a promising synthetic vector for DNA vaccination in various models of human diseases. This vector allows dose sparing of antigen-encoding plasmid DNA. Here, we report the capacity of 704-mediated HIV and anti-hepatocellular carcinoma DNA vaccines to induce the production of specific antibodies against gp120 HIV envelope proteins in mice and against alpha-fetoprotein antigen in non-human primates, respectively. An investigation of the underlying mechanisms showed that 704-mediated vaccination did trigger a strong immune response by (1) allowing a direct DNA delivery into the cytosol, (2) promoting an intracytoplasmic DNA sensing leading to both interferon and NF-κB cascade stimulation, and (3) inducing antigen expression by muscle cells and presentation by antigen-presenting cells, leading to the induction of a robust adaptive response. Overall, our findings suggest that the 704-mediated DNA vaccination platform is an attractive method to develop both prophylactic and therapeutic vaccines.

Tocilizumab-treated convalescent COVID-19 patients retain the cross-neutralization potential against SARS-CoV-2 variants

Although tocilizumab treatment in severe and critical coronavirus disease 2019 (COVID-19) patients has proven its efficacy at the clinical level, there is little evidence supporting the effect of short-term use of interleukin-6 receptor blocking therapy on the B cell sub-populations and the cross-neutralization of SARS-CoV-2 variants in convalescent COVID-19 patients. We performed immunological profiling of 69 tocilizumab-treated and non-treated convalescent COVID-19 patients in total. We observed that SARS-CoV-2-specific IgG1 titers depended on disease severity but not on tocilizumab treatment. The plasma of both treated and non-treated patients infected with the ancestral variant exhibit strong neutralizing activity against the ancestral virus and the Alpha, Beta, and Delta variants of SARS-CoV-2, whereas the Gamma and Omicron viruses were less sensitive to seroneutralization. Overall, we observed that, despite the clinical benefits of short-term tocilizumab therapy in modifying the cytokine storm associated with COVID-19 infections, there were no modifications in the robustness of B cell and IgG responses to Spike antigens.

Oral Delivery of miR-320-3p with Lipidic Aminoglycoside Derivatives at Mid-Lactation Alters miR-320-3p Endogenous Levels in the Gut and Brain of Adult Rats According to Early or Regular Weaning

To investigate if the artificial delivery of microRNAs naturally present in the breastmilk can impact the gut and brain of young rats according to weaning. Animals from a new transgenic rat line expressing the green-fluorescent protein in the endocrine lineage (cholecystokinin expressing cells) received a single oral bolus of miR-320-3p or miR-375-3p embedded in DiOleyl-Succinyl-Paromomycin (DOSP) on D-12. The pups were weaned early (D-15), or regularly (D-30). The expression of relevant miRNA, mRNAs, chromatin complexes, and duodenal cell density were assessed at 8 h post-inoculation and on D-45. The miR-320-3p/DOSP induced immediate effects on H3K4me3 chromatin complexes with polr3d promoter (p < 0.05). On regular weaning, on D-45, miR-320-3p and 375-3p were found to be downregulated in the stomach and upregulated in the hypothalamus (p < 0.001), whereas miR-320-3p was upregulated in the duodenum. After early weaning, miR-320-3p and miR-375-3p were downregulated in the stomach and the duodenum, but upregulated in the hypothalamus and the hippocampus. Combination of miR-320-3p/DOSP with early weaning enhanced miR-320-3p and chromogranin A expression in the duodenum. In the female brain stem, miR-320-3p, miR-504, and miR-16-5p levels were all upregulated. Investigating the oral miRNA-320-3p loads in the duodenal cell lineage paved the way for designing new therapeutics to avoid unexpected long-term impacts on the brain.

COVID-19 vaccines: Frequently asked questions and updated answers

At the end of December 2019, China notified the World Health Organization about a viral pneumonia epidemic soon to be named COVID-19, of which the infectious agent, SARS-CoV-2, was rapidly identified. Less than one year later, published phase 3 clinical trials underlined the effectiveness of vaccines utilizing hitherto unusual technology consisting in injection of the messenger RNA (m-RNA) of a viral protein. In the meantime, numerous clinical trials had failed to identify a maximally effective antiviral treatment, and mass vaccination came to be considered as the strategy most likely to put an end to the pandemic. The objective of this text is to address and hopefully answer the questions being put forward by healthcare professionals on the different anti-SARS-CoV-2 vaccines as regards their development, their modes of action, their effectiveness, their limits, and their utilization in different situations; we are proposing a report on both today's state of knowledge, and the 14 February 2021 recommendations of the French health authorities.

Two repeated motifs enriched within some enhancers and origins of replication are bound by SETMAR isoforms in human colon cells

Setmar is a gene specific to simian genomes. The function(s) of its isoforms are poorly understood and their existence in healthy tissues remains to be validated. Here we profiled SETMAR expression and its genome-wide binding landscape in colon tissue. We found isoforms V3 and V6 in healthy and tumour colon tissues as well as incell lines. In two colorectal cell lines SETMAR binds to several thousand Hsmar1 and MADE1 terminal ends, transposons mostly located in non-genic regions of active chromatin including in enhancers. It also binds to a 12-bp motifs similar to an inner motif in Hsmar1 and MADE1 terminal ends. This motif is interspersed throughout the genome and is enriched in GC-rich regions as well as in CpG islands that contain constitutive replication origins. It is also found in enhancers other than those associated with Hsmar1 and MADE1. The role of SETMAR in the expression of genes, DNA replication and in DNA repair are discussed.

Potential of regulatory T-cell-based therapies in the management of severe COVID-19

“Cytokine storm”, inflammation-mediated severe lung damage and defective haemostasis are the main underlying reasons for morbidity and mortality in coronavirus disease 2019 (COVID-19) patients [1]. Several immunotherapies that target various inflammatory processes have been successfully used in COVID-19 patients and many other strategies are under evaluation [2, 3]. However, in view of dysregulated immune responses in severe COVID-19 patients, we suggest that CD4⁺CD25⁺FoxP3⁺ regulatory T-cell (Treg)-based strategies could be considered for patient management.

In view of dysregulated immune response, “cytokine storm” and inflammation-induced lung damage in severely ill COVID-19 patients, we propose that CD4⁺CD25⁺FoxP3⁺ regulatory T-cell-based therapies could be considered for patient managementhttps://bit.ly/3eKqWPo

Lipidic Aminoglycoside Derivatives: A New Class of Immunomodulators Inducing a Potent Innate Immune Stimulation

Development of simple and fully characterized immunomodulatory molecules is an active area of research to enhance current immunotherapies. Monophosphoryl lipid A (MPL), a nontoxic lipidic derivative from bacteria, is the first and currently only adjuvant approved in humans. However, its capacity to induce a potent response against weak immunogenic tumoral-associated antigens remains limited. Herein, a new generation of lipidic immunomodulators to conduct a structure-activity relationship study to determine the minimal structural elements conferring immunomodulatory properties is introduced. Two lead molecules characterized by a short succinyl linker between two oleyl chains and a polar headgroup consisting of either naturally occurring tobramycin (DOST) or kanamycin (DOSK) are identified. These two lipoaminoglycosides self-assemble in very small vesicles. In a wide variety of cells including 3D human cell culture, DOST and DOSK induce the upregulation of proinflammatory cytokines and interferon-inducible proteins in a dose and time-dependent manner via a caveolae-dependent proinflammatory mechanism and phosphatidylinositol phospholipase C activation. Furthermore, after intratumoral administration, these lipoaminoglycosides induce an efficient immune response leading to significant antitumor activity in a mouse breast cancer model. Altogether, these findings indicate that DOST and DOSK are two groundbreaking synthetic lipid immunostimulators that can be used as adjuvants to enhance current immunotherapeutic treatments.

Oral Delivery of miRNA With Lipidic Aminoglycoside Derivatives in the Breastfed Rat

CONTEXT

Specific targeting of endogenous miRNAs which are involved in epigenetics, may help understanding homeostasis with therapeutic benefits. We use new biologically inspired vehicles consisting of lipoaminoglycosides to deliver in vivo mir-320-3p, a known human breast milk exosomal miRNA, or its antagomiR.

MATERIALS AND METHODS

Four lipoaminoglycosides were screened for cytotoxicity and their biophysical properties. 1-h breast-restricted rats received single-oral treatment of either the lipoaminoglycoside Dioleyl-Succinyl Paromomycin (DOSP) complexed with miRNA or antagomiR, or of control medium at the light on (ZeitGeber Time: ZT-0H) or off (ZT-12H). Glycemia, triglycerides, cholesterol, free-fatty acid were assayed at 0, 4, 8, and 12 h post-treatment. In the stomach, small intestine, liver, plasma, adipose tissue, plexus choroid, and cortex, relevant miRNA with precursors and mRNA (polr3d, hspb6, c-myc, stat1, clock, bmal1, per1, npas2, sirt1-6, and cyclinD1) were quantified by q-PCR. Expression of POLR3D and HSPB6 proteins were analyzed in stomach and liver by Western blot. Immunoprecipitations with anti-AGO1 and 2 were performed on nuclear and cytoplasmic fractions of gastric cells along with detection of miRNA-320-3p in nucleoli. Chromatin ImmunoPrecipitation with anti-Trimethyl-histone-3-Lys-4 and Lys-27 detecting the polr3d promoter and miR-320-3p, were performed for all groups.

RESULTS

Selected DOSP (diameter: 80-200 nm) did not alter gastric extracellular vesicle secretion a few hours after intake. The miR-320-3p was mainly found in gastric or small intestinal cells, reaching the blood and liver in low amount. We have found significant up-regulation of polr3d mRNA (ANOVA, p < 0.0001) at ZT-20H for the miR-320-3p-supplemented group and a higher expression of POLR3D for antagomiR group (ANOVA, p < 0.05). We had a low accumulation of miR-320-3p at ZT-20H in nucleoli, without stat1 evolution. Delivering a high amount of miRNA or antagomiR disrupts RNA-Induced Silencing Complexes in cytoplasm triggering some transfer of extracellular molecules into nuclei with alteration of immune complexes on the polr3d promoter (with a higher amount found in the K4 histone-3-me3 immune complexes at ZT-20H).

CONCLUSION

Extracellular miRNAs embedded in DOSP have a rapid impact on RNAi and on nuclear chromatin complexes depending on the daily rhythm. An integrative view of the impact of extracellular miRNA on physiology will improve assaying epigenetic manipulations following nutritional stress.

Proximity Ligation Assays for In Situ Detection of Innate Immune Activation: Focus on In Vitro-Transcribed mRNA

The characterization of innate immune activation is crucial for vaccine and therapeutic development, including RNA-based vaccines, a promising approach. Current measurement methods quantify type I interferon and inflammatory cytokine production, but they do not allow for the isolation of individual pathways, do not provide kinetic activation or spatial information within tissues, and cannot be translated into clinical studies. Here we demonstrated the use of proximity ligation assays (PLAs) to detect pattern recognition receptor (PRR) activation in cells and in tissue samples. First, we validated PLA's sensitivity and specificity using well-characterized soluble agonists. Next, we characterized PRR activation from in vitro-transcribed (IVT) mRNAs, as well as the effect of sequence and base modifications in vitro. Finally, we established the measurement of PRR activation in tissue sections via PLA upon IVT mRNA intramuscular (i.m.) injection in mice. Overall, our results indicate that PLA is a valuable, versatile, and sensitive tool to monitor PRR activation for vaccine, adjuvant, and therapeutic screening.

Tetrafunctional Block Copolymers Promote Lung Gene Transfer in Newborn Piglets

Tetrafunctional block copolymers are molecules capable of complexing DNA. Although ineffective in vitro, studies in mice have shown that the tetrafunctional block copolymer 704 is a more efficient lung gene transfer agent than the cationic liposome GL67A, previously used in a phase II clinical trial in cystic fibrosis patients. In the present study, we compared the gene transfer capacity of the 704-DNA formulation and a cationic liposome-DNA formulation equivalent to GL67A in a larger-animal model, the newborn piglet. Our results indicate an efficacy of the 704-DNA formulation well above one order of magnitude higher than that of the cationic liposome-DNA formulation, with no elevated levels of interleukin-6 (IL-6), taken as a marker of inflammation. Transgene expression was heterogeneous within lung lobes, with expression levels that were below the detection threshold in some samples, while high in other samples. This heterogeneity is likely to be due to the bolus injection procedure as well as to the small volume of injection. The present study highlights the potential of tetrafunctional block copolymers as non-viral vectors for lung gene therapy.

Amphiphilic block copolymer delivery of a DNA vaccine against Zika virus

Zika virus (ZIKV) is a mosquito-borne flavivirus that was first discovered in 1947. Since then, outbreaks have been reported in tropical Africa, Southeast Asia, the Pacific Islands, and, in 2015, in the Americas. Since 2013, many countries have reported cases of microcephaly and other central nervous system malformation associated with ZIKV. Because the initial target population for a ZIKV vaccine is expected to be women of child-bearing age, including those who may be pregnant, it is necessary to develop safe, easily administered, and non-viral vaccines. Here, we show that a single tetrafunctional Amphiphilic Block Copolymer (ABC) delivers DNA that encodes the full natural sequence of prM-E, among other antigen designs tested, induces the highest antibody titer and neutralization activity against three divergent ZIKV isolates. Vaccination with a single tetrafunctional block copolymer delivering low dose (10 µg) DNA plasmid rapidly induces protection from detectable viremia during acute infection in mice challenged by ZIKV more than 7 months after their first vaccination and boosted 2 weeks before challenge. This use of tetrafunctional ABCs is a new approach to deliver DNA antigens against flaviviruses. The data demonstrate that DNA formulated by a tetrafunctional block copolymer rapidly elicits protective responses against multiple diverse ZIKV isolates. This represents potential for an easy-to-administer and simple to manufacture vaccine candidate against ZIKV and possibly other emerging threats to global health.

Single lipoaminoglycoside promotes efficient intracellular antibody delivery: A comprehensive insight into the mechanism of action

Delivery of biologically active proteins into cells is emerging as important strategy for many applications. Previous experiments have shown that lipoaminoglycosides were capable of delivery of the anti-cytokeratin8 antibody (anti-K8) but only when formulated with lipid helpers potentially leading to toxicity from excess lipids. Here, we optimized anti-K8 delivery with various lipoaminoglycosides in the absence of a lipid helper. Results led to the identification of the aminoglycoside lipid dioleyl phosphoramido ribostamycin (DOPRI) as a potent intracellular delivery system for anti-K8. Electron microscopy revealed that delivered anti-K8 molecules were bound to intermediate filaments in cells. Anti-K8 was bound to the surface of DOPRI vesicles without perturbing lipid organization. Macropinocytosis and caveolin mediated endocytosis contributed to anti-K8 internalization and to filament labeling with a major contribution being made by the caveolin pathway. The results showed that the unique properties of DOPRI were sufficient for efficient intracellular protein delivery without requiring lipid helpers.

Important role of phosphoramido linkage in imidazole-based dioleyl helper lipids for liposome stability and primary cell transfection

BACKGROUND

To optimize synthetic gene delivery systems, there is a need to develop more efficient lipid formulations. Most cationic lipid formulations contain 'helper' neutral lipids because of their ability to increase DNA delivery, in particular by improving endosomal escape of DNA molecules via the pH-buffering effect of protonatable groups and/or fusion with the lipid bilayer of endosomes.

METHODS

We evaluated the influence of the linker structure between the two oleyl chains in the helper lipid on transfection efficiency in cell lines, as well as in primary cells (hepatocytes/cardiomyocytes). We reported the synthesis of two new pH-buffering imidazole helper lipids characterized by a polar headgroup containing one (compound 6) or two (compound 5) imidazole groups and two oleyl chains linked by an amide group. We studied their association with the aminoglycoside lipidic derivative dioleylsuccinylparomomycin (DOSP), which contains two oleyl chains linked to the aminoglycoside polar headgroup via an amide function. We compared the morphology and transfection properties of such binary liposomes of DOSP/5 and DOSP/6 with those of liposomes combining DOSP with another imidazole-based dioleyl helper lipid (MM27) in which a phosphoramido group acts as a linker between the two oleyl chains and imidazole function.

RESULTS

The phosphoramido linker in the helper lipid induces a major difference in terms of morphology and resistance to decomplexation at physical pH for DOSP/helper lipid complexes.

CONCLUSIONS

This hybrid dioleyl linker composition of DOSP/MM27 led to higher transfection efficiency in cell lines and in primary cells compared to complexes with homogeneous dioleyl linker.

Design of Ionizable Lipids To Overcome the Limiting Step of Endosomal Escape: Application in the Intracellular Delivery of mRNA, DNA, and siRNA

The intracellular delivery of nucleic acid molecules is a complex process involving several distinct steps; among these the endosomal escape appeared to be of particular importance for an efficient protein production (or inhibition) into host cells. In the present study, a new series of ionizable vectors, derived from naturally occurring aminoglycoside tobramycin, was prepared using improved synthetic procedures that allow structural variations on the linker and hydrophobic domain levels. Complexes formed between the new ionizable lipids and mRNA, DNA, or siRNA were characterized by cryo-TEM experiments and their transfection potency was evaluated using different cell types. We demonstrated that lead molecule 30, bearing a biodegradable diester linker, formed small complexes with nucleic acids and provided very high transfection efficiency with all nucleic acids and cell types tested. The obtained results suggested that the improved and "universal" delivery properties of 30 resulted from an optimized endosomal escape, through the lipid-mixing mechanism.

RILES, a novel method for temporal analysis of the in vivo regulation of miRNA expression

Novel methods are required to investigate the complexity of microRNA (miRNA) biology and particularly their dynamic regulation under physiopathological conditions. Herein, a novel plasmid-based RNAi-Inducible Luciferase Expression System (RILES) was engineered to monitor the activity of endogenous RNAi machinery. When RILES is transfected in a target cell, the miRNA of interest suppresses the expression of a transcriptional repressor and consequently switch-ON the expression of the luciferase reporter gene. Hence, miRNA expression in cells is signed by the emission of bioluminescence signals that can be monitored using standard bioluminescence equipment. We validated this approach by monitoring in mice the expression of myomiRs-133, −206 and −1 in skeletal muscles and miRNA-122 in liver. Bioluminescence experiments demonstrated robust qualitative and quantitative data that correlate with the miRNA expression pattern detected by quantitative RT-PCR (qPCR). We further demonstrated that the regulation of miRNA-206 expression during the development of muscular atrophy is individual-dependent, time-regulated and more complex than the information generated by qPCR. As RILES is simple and versatile, we believe that this methodology will contribute to a better understanding of miRNA biology and could serve as a rationale for the development of a novel generation of regulatable gene expression systems with potential therapeutic applications.

Treatment efficacy of DNA lipid nanocapsules and DNA multimodular systems after systemic administration in a human glioma model

BACKGROUND

We previously developed different types of DNA nanocarriers for systemic administration. Recently, the biodistribution profiles of these intravenously administered nanocarriers, DNA lipid nanocapsules (LNCs) and different multimodular systems (MMS), were analysed in healthy mice using in vivo biofluorescence imaging.

METHODS

In the present study, the experiments were performed in an ectopic human U87MG glioma model in nude mice. First, the biodistribution profiles of intravenously administered multimodular systems delivering a plasmid DNA with a luciferase cassette were analysed using in vivo biofluorescence imaging. Afterwards, a systemic treatment with two long circulating DNA nanocarriers, poly(ethylene glycol) (PEG) DNA LNCs and galactose (GAL) DNA MMS dioleylamin-succinyl paromomycin (DOSP) was performed on this glioma model using a plasmid encoding the herpes simplex virus thymidine kinase (HSV-tk) and subsequent ganciclovir (GCV) treatment.

RESULTS

The biodistribution profiles of the different DNA nanocarriers on this glioma model were similar to those observed on healthy animals and varied in function of their cationic lipid composition and their surface characteristics. Furthermore, PEG DNA LNCs and GAL DNA MMS DOSP showed a specific accumulation and some luciferase expression in the tumour tissue. The systemic treatment using the HSV-tk/GCV approach showed a tumour growth reduction compared to the nontreated mice cohort.

CONCLUSIONS

These results are in good accordance with those obtained previously with PEG DNA LNCs in a human melanoma mouse model and highlight the potential use of GAL DNA MMS DOSP and PEG DNA LNCs as future therapeutics in glioma and other cancers.

DNA nanocarriers for systemic administration: characterization and in vivo bioimaging in healthy mice

We hereby present different DNA nanocarriers consisting of new multimodular systems (MMS), containing the cationic lipid dioleylaminesuccinylparomomycin (DNA MMS DOSP), or bis (guanidinium)-tren-cholesterol (DNA MMS BGTC), and DNA lipid nanocapsules (DNA LNCs). Active targeting of the asialoglycoprotein receptor (ASGP-R) using galactose as a ligand for DNA MMS (GAL DNA MMS) and passive targeting using a polyethylene glycol coating for DNA LNCs (PEG DNA LNCs) should improve the properties of these DNA nanocarriers. All systems were characterized via physicochemical methods and the DNA payload of DNA LNCs was quantified for the first time. Afterwards, their biodistribution in healthy mice was analyzed after encapsulation of a fluorescent dye via in vivo biofluorescence imaging (BFI), revealing various distribution profiles depending on the cationic lipid used and their surface characteristics. Furthermore, the two vectors with the best prolonged circulation profile were administered twice in healthy mice revealing that the new DNA MMS DOSP vectors showed no toxicity and the same distribution profile for both injections, contrary to PEG DNA LNCs which showed a rapid clearance after the second injection, certainly due to the accelerated blood clearance phenomenon.

DNA/amphiphilic block copolymer nanospheres reduce asthmatic response in a mouse model of allergic asthma

Asthma is a chronic, inflammatory, respiratory disease caused by an abnormal reactivity against allergens. The most promising treatments for asthma are based on specific immunotherapies, but they lack efficiency and can induce deleterious side effects. Among new modalities of immunotherapy currently in development, DNA vaccination presents a promising approach, as it enables targeted immunotherapy in association with reduced allergenicity. We have developed an innovative, DNA-based vaccine against Dermatophagoides farinae 1 allergen (Der f 1), one of the allergens most commonly encountered by asthma patients in Europe. Intramuscular administration of a Der f 1-encoding plasmid formulated with the block copolymer 704 in healthy mice induced a strong humoral and cellular response with a pro-helper T cell type 1 bias. Administration of the same formulation in asthmatic mice, according to an early vaccination protocol, led to a reduction of airway hyperresponsiveness and a significant decrease in the level of inflammatory cytokines in the bronchoalveolar lavage of Der f 1-vaccinated mice.

Evidence of DNA transfer across a model membrane by a neutral amphiphilic block copolymer

BACKGROUND

Neutral amphiphilic triblock copolymers have been shown to be efficient for gene transfection in vivo, especially by direct injection into the muscle. To contribute to a better understanding of the underlying mechanisms, in the present study, we investigated the properties of a poly(ethylene oxide-b-4-vinylpyridine) diblock copolymer as vector for nucleic acid transfer, with the particular aim of shedding some light on a possible mechanism explaining the internalization of DNA by the transfected cells.

METHODS

Complexation of plasmid DNA with the PEO-b-P4VP diblock copolymer was investigated by ethidium bromide exclusion and gel electrophoresis assays. Interaction of the copolymer with a lipid model membrane was evaluated by electrophysiological assays and quantification of plasmid DNA was performed by quantitative polymerase chain reaction. In vivo luciferase transfection assays were finally performed.

RESULTS

The diblock copolymer was found to poorly interact with DNA up to a mass ratio (copolymer/DNA) as high as 150. At a concentration of 36 µg/ml, it induced the formation of mainly transient (but sometimes permanent) pores and the formation of those pores allowed the translocation of plasmid DNA across the model membrane. However, only low transgene expression was obtained; the luciferase levels observed with the diblock being of the same order of magnitude as those observed with the corresponding PEO and P4VP homopolymers.

CONCLUSIONS

These results strongly suggest that gene transfection by neutral block copolymers may involve the formation of cellular pores; in addition, they also highlight that in vivo gene transfection requires the use of adequately soluble block copolymers.

Novel approach for the development of new antibodies directed against transposase-derived proteins encoded by human neogenes

Molecular domestication of several DNA transposons has occurred during the evolution of the primate lineage, and has led to the emergence of at least 42 new genes known as neogenes. Because these genes are derived from transposons, they encode proteins that are related to certain recombinases, known as transposases. Consequently, they may make an important contribution to the genetic instability of some human cells. In order to investigate the role of these neogenes, we need to be able to study their expression as proteins, for example in tumours, which often provide good models of genetic instability. In order to perform such studies, polyclonal antibodies directed against the proteins expressed by neogenes are obtained using a recently developed new method of Nanospheres/DNA immunisation in laboratory mammals. In this chapter, we describe a fully integrated process of producing antibodies that consists of a series of steps starting with the preparation and synthetic formulation of plasmids encoding neogenes, and culminating in the final production and confirmation of the quality of these polyclonal antibodies.

CCL5 neutralization restricts cancer growth and potentiates the targeting of PDGFRβ in colorectal carcinoma

Increased CCL5 levels are markers of an unfavourable outcome in patients with melanoma, breast, cervical, prostate, gastric or pancreatic cancer. Here, we have assessed the role played by CCL5/CCR5 interactions in the development of colon cancer. To do so, we have examined a number of human colorectal carcinoma clinical specimens and found CCL5 and its receptors over-expressed within primary as well as liver and pulmonary metastases of patients compared to healthy tissues. In vitro, CCL5 increased the growth and migratory responses of colon cancer cells from both human and mouse origins. In addition, systemic treatment of mice with CCL5-directed antibodies reduced the extent of development of subcutaneous colon tumors, of liver metastases and of peritoneal carcinosis. Consistently, we found increased numbers of CD45-immunoreactive cells within the stroma of the remaining lesions as well as at the interface with the healthy tissue. In contrast, selective targeting of CCR5 through administration of TAK-779, a CCR5 antagonist, only partially compromised colon cancer progression. Furthermore, CCL5 neutralization rendered the tumors more sensitive to a PDGFRβ-directed strategy in mice, this combination regimen offering the greatest protection against liver metastases and suppressing macroscopic peritoneal carcinosis. Collectively, our data demonstrate the involvement of CCL5 in the pathogenesis of colorectal carcinoma and point to its potential value as a therapeutic target.

AFP-specific immunotherapy impairs growth of autochthonous hepatocellular carcinoma in mice

BACKGROUND AND AIMS

In this study, we have assessed the potential of antigen-specific immunotherapy against hepatocellular carcinoma (HCC) in conditions of low tumour burden, in an autochthonous HCC model.

METHODS

Diethylnitrosamine (DEN) injected into infant mice results in the development of multi-nodular HCC in which alpha-fetoprotein (AFP) is re-expressed. DEN-injected animals received an antigen-specific immunization with a synthetic vector consisting of a low dose of AFP-encoding plasmid formulated with the amphiphilic block copolymer 704 (DNAmAFP/704). Animals were treated at 4 and 5 months, before macroscopic nodules were detected, and were sacrificed at 8 months. The tumour burden, as well as liver histology, was assessed. AFP and MHC class I molecule expression in the nodules were monitored by qRT-PCR.

RESULTS

The AFP-specific immunotherapy led to a significant (65%) reduction in tumour size. The reduced expression of AFP and MHC class I molecules was measured in the remaining nodules taken from the DNAmAFP/704-treated group.

CONCLUSIONS

This is the first study demonstrating the relevance of antigen-specific immunotherapy in an autochthonous HCC model. In this context, we validated the use of an anti-tumour immunotherapy based on vaccination with nanoparticles consisting of low dose antigen-encoding DNA formulated with a block copolymer. Our results demonstrate the potential of this strategy as adjuvant immunotherapy to reduce the recurrence risk after local treatment of HCC patients.

Probing the in vitro mechanism of action of cationic lipid/DNA lipoplexes at a nanometric scale

Cationic lipids are used for delivering nucleic acids (lipoplexes) into cells for both therapeutic and biological applications. A better understanding of the identified key-steps, including endocytosis, endosomal escape and nuclear delivery is required for further developments to improve their efficacy. Here, we developed a labelling protocol using aminated nanoparticles as markers for plasmid DNA to examine the intracellular route of lipoplexes in cell lines using transmission electron microscopy. Morphological changes of lipoplexes, membrane reorganizations and endosomal membrane ruptures were observed allowing the understanding of the lipoplex mechanism until the endosomal escape mediated by cationic lipids. The study carried out on two cationic lipids, bis(guanidinium)-tris(2-aminoethyl)amine-cholesterol (BGTC) and dioleyl succinyl paramomycin (DOSP), showed two pathways of endosomal escape that could explain their different transfection efficiencies. For BGTC, a partial or complete dissociation of DNA from cationic lipids occurred before endosomal escape while for DOSP, lipoplexes remained visible within ruptured vesicles suggesting a more direct pathway for DNA release and endosome escape. In addition, the formation of new multilamellar lipid assemblies was noted, which could result from the interaction between cationic lipids and cellular compounds. These results provide new insights into DNA transfer pathways and possible implications of cationic lipids in lipid metabolism.

Amphiphilic block copolymers enhance the cellular uptake of DNA molecules through a facilitated plasma membrane transport

Amphiphilic block copolymers have been developed recently for their efficient, in vivo transfection activities in various tissues. Surprisingly, we observed that amphiphilic block copolymers such as Lutrol® do not allow the transfection of cultured cells in vitro, suggesting that the cell environment is strongly involved in their mechanism of action. In an in vitro model mimicking the in vivo situation we showed that pre-treatment of cells with Lutrol®, prior to their incubation with DNA molecules in the presence of cationic lipid, resulted in higher levels of reporter gene expression. We also showed that this improvement in transfection efficiency associated with the presence of Lutrol® was observed irrespective of the plasmid promoter. Considering the various steps that could be improved by Lutrol®, we concluded that the nucleic acids molecule internalization step is the most important barrier affected by Lutrol®. Microscopic examination of transfected cells pre-treated with Lutrol® confirmed that more plasmid DNA copies were internalized. Absence of cationic lipid did not impair Lutrol®-mediated DNA internalization, but critically impaired endosomal escape. Our results strongly suggest that in vivo, Lutrol® improves transfection by a physicochemical mechanism, leading to cellular uptake enhancement through a direct delivery into the cytoplasm, and not via endosomal pathways.

Developing cell therapy techniques for respiratory disease: intratracheal delivery of genetically engineered stem cells in a murine model of airway injury

Interest has increased in the use of exogenous stem cells to optimize lung repair and serve as carriers of a therapeutic gene for genetic airway diseases such as cystic fibrosis. We investigated the survival and engraftment of exogenous stem cells after intratracheal injection, in a murine model of acute epithelial airway injury already used in gene therapy experiments on cystic fibrosis. Embryonic stem cells and mesenchymal stem cells were intratracheally injected 24 hr after 2% polidocanol administration, when epithelial airway injury was maximal. Stem cells were transfected with reporter genes immediately before administration. Reporter gene expression was analyzed in trachea-lungs and bronchoalveolar lavage, using nonfluorescence, quantitative, and sensitive methods. Enzyme-linked immunosorbent assay quantitative results showed that 0.4 to 5.5% of stem cells survived in the injured airway. Importantly, no stem cells survived in healthy airway or in the epithelial lining fluid. Using 5-bromo-4-chloro-3-indolyl-beta-d-galactopyranoside staining, transduced mesenchymal stem cells were detected in injured trachea and bronchi lumen. When the epithelium was spontaneously regenerated, the in vivo amount of engrafted mesenchymal stem cells from cell lines decreased dramatically. No stem cells from primary culture were located within the lungs at 7 days. This study demonstrated the feasibility of intratracheal cell delivery for airway diseases with acute epithelial injury.

Trafficking-deficient long QT syndrome mutation KCNQ1-T587M confers severe clinical phenotype by impairment of KCNH2 membrane localization: evidence for clinically significant IKr-IKs alpha-subunit interaction

BACKGROUND

KCNQ1-T587M is a trafficking-deficient long QT syndrome (LQTS) missense mutation. Affected patients exhibit severe clinical phenotypes that are not explained by the mutant's effects on I(Ks). Previous work showed a KCNH2 and KCNQ1 alpha-subunit interaction that increases KCNH2 membrane localization and function.

OBJECTIVE

We hypothesized that failure of trafficking-deficient KCNQ1-T587M to enhance KCNH2 membrane expression could reduce KCNH2 current versus wild-type KCNQ1 (KCNQ1-WT), contributing to the LQTS phenotype of KCNQ1-T587M carriers.

METHODS

Patch-clamp, protein biochemical studies, confocal imaging, and in vivo transfection of guinea pig cardiomyocytes were performed.

RESULTS

KCNQ1-T587M failed to generate functional current when coexpressed with KCNE1 and caused haploinsufficiency when coexpressed with KCNQ1-WT/KCNE1. Coexpression of KCNQ1-WT with KCNH2 increased I(KCNH2) versus KCNH2 alone (P <.05). Immunoblots and confocal microscopy indicated increased plasma membrane localization of KCNH2 alpha-subunits in cells cotransfected with KCNQ1-WT plasmid, while total KCNH2 protein synthesis and KCNH2 glycosylation remained unaffected, which suggests a chaperone effect of KCNQ1-WT to enhance the membrane localization of KCNH2. KCNH2 also coimmunoprecipitated with KCNQ1-WT. Although KCNQ1-T587M coprecipitated with KCNH2, the mutant was retained intracellularly and failed to increase KCNH2 membrane localization, abolishing the KCNQ1-WT chaperone function and reducing I(KCNH2) upon coexpression substantially compared with coexpression with KCNQ1-WT (P <.05). In vivo transfection of KCNQ1-T587M in guinea pigs suppressed I(Kr) in isolated cardiomyocytes.

CONCLUSION

The trafficking-deficient LQTS mutation KCNQ1-T587M fails to show the chaperoning function that enhances KCNH2 membrane localization with KCNQ1-WT. This novel mechanism results in reduced I(KCNH2), which would be expected to decrease repolarization reserve and synergize with reduced I(KCNQ1) caused directly by the mutation, potentially explaining the malignant clinical phenotype in affected patients.

The encapsulation of DNA molecules within biomimetic lipid nanocapsules

Most of DNA synthetic complexes result from the self-assembly of DNA molecules with cationic lipids or polymers in an aqueous controlled medium. However, injection of such self-assembled complexes in medium like blood that differ from that of their formulation leads to strong instability. Therefore, DNA vectors that have physico-chemical properties and structural organisation that will not be sensitive to a completely different medium in terms of ionic and protein composition are actively sought. To this end, the goal here was to discover and optimize a nanostructured system where DNA molecules would be encapsulated in nanocapsules consisting in an oily core and a shell covered by PEG stretches obtained through a nanoemulsion process in the absence of organic solvent. This encapsulation form of DNA molecules would prevent interactions with external hostile biological fluid. The results show the entrapment of lipoplexes into lipid nanocapsules, leading to the formation of neutral 110 nm-DNA nanocapsules. They were weakly removed by the immune system, displaying an increased blood half-life, and improved carcinoma cell transfection, in comparison to the parent lipoplexes. Our results demonstrate that the fabrication of nanocapsules encapsulating hydrophilic DNA in an oily core that meet criteria for blood injection is possible.

Cancer-specific transgene expression mediated by systemic injection of nanoparticles

The lack of safe and efficient systemic gene delivery vectors has largely reduced the potential of gene therapy in the clinic. Previously, we have reported that polypropylenimine dendrimer PPIG3/DNA nanoparticles are capable of tumor transfection upon systemic administration in tumor-bearing mice. To be safely applicable in the clinic, it is crucial to investigate the colloidal stability of nanoparticles and to monitor the exact biodistribution of gene transfer in the whole body of the live subject. Our biophysical characterization shows that dendrimers, when complexed with DNA, are capable of forming spontaneously in solution a supramolecular assembly that possesses all the features required to diffuse in experimental tumors through the enhanced permeability and retention effect. We show that these nanoparticles are of sizes ranging from 33 to 286 nm depending on the DNA concentration, with a colloidal stable and well-organized fingerprint-like structure in which DNA molecules are condensed with an even periodicity of 2.8 nm. Whole-body nuclear imaging using small-animal nano-single-photon emission computed tomography/computer tomography scanner and the human Na/I symporter (NIS) as reporter gene shows unique and highly specific tumor targeting with no detection of gene transfer in any of the other tissues of tumor-bearing mice. Tumor-selective transgene expression was confirmed by quantitative reverse transcription-PCR at autopsy of scanned animals, whereas genomic PCR showed that the tumor sites are the predominant sites of nanoparticle accumulation. Considering that NIS imaging of transgene expression has been recently validated in humans, our data highlight the potential of these nanoparticles as a new formulation for cancer gene therapy.

Glycosaminoglycans as potential regulators of osteoprotegerin therapeutic activity in osteosarcoma

Osteosarcoma is the most frequent primary bone malignant tumor that develops mainly in children and adolescents. Despite recent improvements in chemotherapy and surgery, survival rate is approximately 50% after 5 years. Osteoprotegerin (OPG) is a potent inhibitor of osteoclast differentiation and activation, but its use as therapeutic agent in cancer-associated osteolysis remains controversial due to its ability to bind and inhibit the apoptotic effect of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on tumor cells. The therapeutic effects of full-length OPG (1-401) and OPG 1-194 lacking its heparin-binding domain delivered by nonviral gene therapy were compared in a murine model of osteolytic osteosarcoma. Tumor incidence, progression, and associated bone lesions were significantly diminished in the OPG 1-194 group, but not in the OPG 1-401 group, compared with controls. As receptor activator of nuclear factor-kappaB ligand (RANKL), TRAIL, and glycosaminoglycans (GAG) were shown to be overexpressed in osteosarcoma environment compared with control tissue, OPG 1-401 bioactivity may be modulated by one of these protagonists. Surface plasmon resonance analyses performed with OPG, TRAIL, and GAGs revealed that TRAIL binds both forms of OPG with the same affinity. In addition, as OPG 1-194 and OPG 1-401 similarly inhibit TRAIL-induced apoptosis, it suggests that TRAIL is not involved in the modulation of OPG bioactivity. However, as GAGs inhibit OPG 1-401 but not OPG 1-194 binding to TRAIL or to RANKL, they may represent potent regulators of OPG availability and antitumor activity in bone tumor microenvironment.

Galactosylated multimodular lipoplexes for specific gene transfer into primary hepatocytes

BACKGROUND

Numerous synthetic cationic vectors have been synthesized and are successfully used for in vitro gene transfer but an excess of positive charges can lead to cytotoxicity and does not enable specific transfection.

METHODS

We decided to develop alternative molecular systems consisting of neutral, colloidally stable bioassemblies equipped with ligands for specific cell targeting. Consequently, we directed our efforts toward the development of a multimodular non-viral gene delivery system consisting of a condensed core of DNA with cationic liposomes of bis(guanidinium)-tren-cholesterol and an external corona of poly(ethylene oxide) stretches harbored by the steric stabilizers used to stabilize lipoplexes colloidally. A ligand capable of cell targeting by receptor-mediated endocytosis was covalently linked at the poly(ethylene oxide) extremity of steric stabilizers. Steric stabilizers were functionalized by a one-step enzymatic galactosylation to develop new supramolecular assemblies of lipoplexes able to target asialoglycoprotein receptors located on primary hepatocytes.

RESULTS

Cryo-TEM and fluorescence experiments showed that DNA was condensed within lamellar complexes whose size ranged between 100 to 300 nm in diameter. Bis(guanidinium)-tren-cholesterol-DNA lipoplexes, colloidally stabilized by galactosylated steric stabilizers at a galactosylated steric stabilizer/DNA ratio of 300, led to specific transfection of primary hepatocytes whereas ungalactosylated steric stabilizer did not transfect.

CONCLUSIONS

Our findings confirm the receptor-mediated endocytosis pathway of galactosylated multimodular lipoplexes. Thus, we conclude that the fabrication of a multimodular assembly harboring a ligand without non-specific interaction with cell membranes is possible and a highly promising system to transfect other primary or cultured cells specifically through a receptor-dependent mechanism.

Therapeutic efficacy of soluble receptor activator of nuclear factor-kappa B-Fc delivered by nonviral gene transfer in a mouse model of osteolytic osteosarcoma

Osteosarcoma is the most frequent primary bone tumor that develops mainly during youth, the median age of diagnosis being 18 years. Despite improvement in osteosarcoma treatment, survival rate is only 30% after 5 years for patients with pulmonary metastases at diagnosis. This warrants exploration of new therapeutic options. The anti-bone resorption molecule receptor activator of NF-kappaB (RANK) is very promising, as it may block the vicious cycle between bone resorption and tumor proliferation that takes place during tumor development in bone site. The cDNA encoding murine RANK-Fc (mRANK-Fc) was administered by gene transfer using an amphiphilic polymer in a mouse model of osteolytic osteosarcoma. Clinical and bone microarchitecture variables were assessed by radiography and micro-CT analyses. In vitro experiments were designed to determine the mechanism of action of RANK-Fc on tumor cell proliferation (XTT assays), apoptosis (caspase activation), cell cycle distribution (fluorescence-activated cell sorting analysis), or gene expression (reverse transcription-PCR). RANK-Fc was effective in preventing the formation of osteolytic lesions associated with osteosarcoma development and in reducing the tumor incidence, the local tumor growth, and the lung metastases dissemination leading to a 3.9-fold augmentation of mice survival 28 days after implantation. On the contrary, mRANK-Fc did not prevent the development of nonosseous tumor nodules, suggesting that bone environment is necessary for mRANK-Fc therapeutic efficacy. Furthermore, mRANK-Fc has no direct activity on osteosarcoma cells in vitro. mRANK-Fc exerts an indirect inhibitory effect on osteosarcoma progression through inhibition of bone resorption.