Corrigendum: Optimized riboswitch-regulated AAV vector for VEGF-B gene therapy

[This corrects the article DOI: 10.3389/fmed.2022.1052318.].

Antiangiogenic AAV2 gene therapy with a truncated form of soluble VEGFR-2 reduces the growth of choroidal neovascularization in mice after intravitreal injection

Pathological angiogenesis related to neovascularization in the eye is mediated through vascular endothelial growth factors (VEGFs) and their receptors. Ocular neovascular-related diseases are mainly treated with anti-VEGF agents. In this study we evaluated the efficacy and safety of novel gene therapy using adeno associated virus 2 vector expressing a truncated form of soluble VEGF receptor-2 fused to the Fc-part of human IgG1 (AAV2-sVEGFR-2-Fc) to inhibit ocular neovascularization in laser induced choroidal neovascularization (CNV) in mice. The biological activity of sVEGFR-2-Fc was determined in vitro. It was shown that sVEGFR-2-Fc secreted from ARPE-19 cells was able to bind to VEGF-A₁₆₅ and reduce VEGF-A₁₆₅ induced cell growth and survival. A single intravitreal injection (IVT) of AAV2-sVEGFR-2-Fc (1 μl, 4.7 × 10¹² vg/ml) one-month prior laser photocoagulation did not cause any changes in the retinal morphology and significantly suppressed fluorescein leakage at 7, 14, 21 and 28 days post-lasering compared to controls. Macrophage infiltration was observed after the injection of both AAV2-sVEGFR-2-Fc and PBS. Our findings indicate that AAV2 mediated gene delivery of the sVEGFR-2-Fc efficiently reduces formation of CNV and could be developed to a therapeutic tool for the treatment of retinal diseases associated with neovascularization.

Lentiviral interferon: A novel method for gene therapy in bladder cancer

Interferon alpha (IFNα) gene therapy is emerging as a new treatment option for patients with non-muscle invasive bladder cancer (NMIBC). Adenoviral vectors expressing IFNα have shown clinical efficacy treating bacillus Calmette-Guerin (BCG)-unresponsive bladder cancer (BLCA). However, transient transgene expression and adenoviral immunogenicity may limit therapeutic activity. Lentiviral vectors can achieve stable transgene expression and are less immunogenic. In this study, we evaluated lentiviral vectors expressing murine IFNα (LV-IFNα) and demonstrate IFNα expression by transduced murine BLCA cell lines, bladder urothelium, and within the urine following intravesical instillation. Murine BLCA cell lines (MB49 and UPPL1541) were sensitive to IFN-mediated cell death after LV-IFNα, whereas BBN975 was inherently resistant. Upregulation of interleukin-6 (IL-6) predicted sensitivity to IFN-mediated cell death mediated by caspase signaling, which when inhibited abrogated IFN-mediated cell killing. Intravesical therapy with LV-IFNα/Syn3 in a syngeneic BLCA model significantly improved survival, and molecular analysis of treated tumors revealed upregulation of apoptotic and immune-cell-mediated death pathways. In particular, biomarker discovery analysis identified three clinically actionable targets, PD-L1, epidermal growth factor receptor (EGFR), and ALDHA1A, in murine tumors treated with LV-IFNα/Syn3. Our findings warrant the comparison of adenoviral and LV-IFNα and the study of novel combination strategies with IFNα gene therapy for the BLCA treatment.

Novel Designed Proteolytically Resistant VEGF-B186R127S Promotes Angiogenesis in Mouse Heart by Recruiting Endothelial Progenitor Cells

Background: Previous studies have indicated that vascular endothelial growth factor B186 (VEGF-B186) supports coronary vascular growth in normal and ischemic myocardium. However, previous studies also indicated that induction of ventricular arrhythmias is a severe side effect preventing the use of VEGF-B186 in cardiac gene therapy, possibly mediated by binding to neuropilin 1 (NRP1). We have designed a novel VEGF-B186 variant, VEGF-B186R127S, which is resistant to proteolytic processing and unable to bind to NRP1. Here, we studied its effects on mouse heart to explore the mechanism of VEGF-B186-induced vascular growth along with its effects on cardiac performance.

Methods: Following the characterization of VEGF-B186R127S, we performed ultrasound-guided adenoviral VEGF-B186R127S gene transfers into the murine heart. Vascular growth and heart functions were analyzed using immunohistochemistry, RT-PCR, electrocardiogram and ultrasound examinations. Endothelial progenitor cells (EPCs) were isolated from the circulating blood and characterized. Also, in vitro experiments were carried out in cardiac endothelial cells with adenoviral vectors.

Results: The proteolytically resistant VEGF-B186R127S significantly induced vascular growth in mouse heart. Interestingly, VEGF-B186R127S gene transfer increased the number of circulating EPCs that secreted VEGF-A. Other proangiogenic factors were also present in plasma and heart tissue after the VEGF-B186R127S gene transfer. Importantly, VEGF-B186R127S gene transfer did not cause any side effects, such as arrhythmias.

Conclusion: VEGF-B186R127S induces vascular growth in mouse heart by recruiting EPCs. VEGF-B186R127S is a novel therapeutic agent for cardiac therapeutic angiogenesis to rescue myocardial tissue after an ischemic insult.

Optimized riboswitch-regulated AAV vector for VEGF-B gene therapy

Gene therapy would greatly benefit from a method to regulate therapeutic gene expression temporally. Riboswitches are small RNA elements that have been studied for their potential use in turning transgene expression on or off by ligand binding. We compared several tetracycline and toyocamycin-inducible ON-riboswitches for a drug responsive transgene expression. The tetracycline-dependent K19 riboswitch showed the best control and we successfully applied it to different transgenes. The induction of gene expression was 6- to 10-fold, dose-dependent, reversible, and occurred within hours after the addition of a clinically relevant tetracycline dose, using either plasmid or adeno-associated virus (AAV) vectors. To enhance the switching capacity, we further optimized the gene cassette to control the expression of a potential therapeutic gene for cardiovascular diseases, VEGF-B. Using two or three riboswitches simultaneously reduced leakiness and improved the dynamic range, and a linker sequence between the riboswitches improved their functionality. The riboswitch function was promoter-independent, but a post-transcriptional WPRE element in the expression cassette reduced its functionality. The optimized construct was a dual riboswitch at the 3' end of the transgene with a 100 bp linker sequence. Our study reveals significant differences in the function of riboswitches and provides important aspects on optimizing expression cassette designs. The findings will benefit further research and development of riboswitches.

Adenoviral VEGF-B186R127S gene transfer induces angiogenesis and improves perfusion in ischemic heart

Vascular endothelial growth factor B (VEGF-B) is an interesting therapeutic candidate for coronary artery disease. However, it can also cause ventricular arrhythmias, potentially preventing its use in clinics. We cloned VEGF-B isoforms with different receptor binding profiles to clarify the roles of VEGFR-1 and Nrp-1 in angiogenesis and to see if angiogenic properties can be maintained while avoiding side effects. VEGF-B constructs were studied in vivo using adenovirus (Ad)-mediated intramyocardial gene transfers into the normoxic and ischemic porcine heart (n = 51). It was found that the unprocessed isoform VEGF-B186R127S is as efficient angiogenic growth factor as the native VEGF-B186 in normoxic and ischemic heart. In addition, AdVEGF-B186R127S increased myocardial perfusion reserve by 22% in ischemic heart without any side effects. AdVEGF-B127 (VEGFR-1 and Nrp-1 ligand) and AdVEGF-B109 (VEGFR-1 ligand) did not induce angiogenesis. Thus, VEGF-B186 is angiogenic only before its proteolytic processing to VEGF-B127. Only the VEGF-B186 C-terminal fragment was associated with arrhythmias.

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AdVEGF-B186R127S induces angiogenesis and improves perfusion in the ischemic heart

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No significant side effects were observed after AdVEGF-B186R127S therapy

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VEGF-B186 is angiogenic only prior to its proteolytic processing

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C-terminal fragment of VEGF-B186 is associated with ventricular arrhythmias

Functional roles of the membrane-associated AAV protein MAAP

With a limited coding capacity of 4.7 kb, adeno-associated virus (AAV) genome has evolved over-lapping genes to maximise the usage of its genome. An example is the recently found ORF in the cap gene, encoding membrane-associated accessory protein (MAAP), located in the same genomic region as the VP1/2 unique domain, but in a different reading frame. This 13 KDa protein, unique to the dependovirus genus, is not homologous to any known protein. Our studies confirm that MAAP translation initiates from the first CTG codon found in the VP1 ORF2. We have further observed MAAP localised in the plasma membrane, in the membranous structures in close proximity to the nucleus and to the nuclear envelope by co-transfecting with plasmids encoding the wild-type AAV (wt-AAV) genome and adenovirus (Ad) helper genes. While keeping VP1/2 protein sequence identical, both inactivation and truncation of MAAP translation affected the emergence and intracellular distribution of the AAV capsid proteins. We have demonstrated that MAAP facilitates AAV replication and has a role in controlling Ad infection. Additionally, we were able to improve virus production and capsid integrity through a C-terminal truncation of MAAP while other modifications led to increased packaging of contaminating, non-viral DNA. Our results show that MAAP plays a significant role in AAV infection, with profound implications for the production of therapeutic AAV vectors.

RSV Specific Antibodies in Pregnant Women and Subsequent Risk of RSV Hospitalization in Young Infants

Background

The fusion (F) glycoprotein of respiratory syncytial virus (RSV) represents the major neutralizing antigen, and antibodies against the pre-F conformation have the most potent neutralizing activity. This study aimed to assess the correlation between maternal antibody titers against the pre-F, post-F, and G glycoproteins and the child’s risk of developing severe RSV bronchiolitis early in infancy.

Methods

We identified previously healthy term infants <3 months of age hospitalized with RSV bronchiolitis from December 2015 to March 2016. We measured IgG antibody titers to pre-F, post-F, and G proteins in maternal sera obtained at 9–12 weeks of pregnancy of these hospitalized infants’ mothers (n = 94) and compared them with serum antibody titers of control pregnant mothers (n = 130) whose children were not hospitalized.

Results

All maternal samples (n = 224) had detectable pre-F antibodies. Pre-F antibody titers were significantly lower in mothers whose infants were hospitalized with RSV bronchiolitis compared with those mothers whose infants were not hospitalized (23.9 [range (or antibody titer range), 1.4–273.7] µg/L vs 30.6 [XXX, 3.4–220.0] µg/L; P = .0026). There were no significant differences in maternal post-F and G antibody titers between hospitalized and nonhospitalized infants.

Conclusions

Our findings indicate that maternal pre-F antibodies are fundamental for providing immune protection to the infant.

Every fifth child and adolescent in Finland is overweight

Background

Globally, the prevalence of child and adolescent overweight and obesity has increased during the preceding decades leading to childhood obesity being acknowledged as one of the most significant health hazards of the 21st century. Yet, in Finland comprehensive and up-to-date data on the prevalence of overweight and obesity among children and adolescents have been lacking. The aim of this study was to examine the prevalence of overweight and obesity among 2-16-year-old children and adolescents living in Finland in 2018.

Methods

The study was based on height and weight measurements taken at child welfare clinics and school health services between 5.7.2017 and 5.4.2019 (n = 375,561). The data was collected from the Register of Primary Health Care Visits. Child and adolescent overweight and obesity were defined according to international IOTF BMI criteria (age- and sex-specific BMI cut-off points corresponding to adults' cut-off points of 25 kg/m2 for overweight and 30 kg/m2 for obesity) and reported by age group and sex.

Results

In 2018, nearly 20% of boys and girls aged 2-16 years were classified as at least overweight while the prevalence of obesity was 5% among both sexes. The prevalence of overweight in pre-school-aged children (2-6 years) was 12% in boys and 15% in girls, in primary school-aged children (7-12 years) 23% in boys and 22% in girls and in adolescents (13-16 years) 25% in boys and 23% in girls.

Conclusions

In 2018, every fifth child and adolescent in Finland was classified as either overweight or obese. The prevalence of overweight and obesity appears to increase with age in both genders.

Key messages

Childhood and adolescent overweight and obesity were comparatively common in Finland in 2018. As overweight and obesity often persist into adulthood, multi-professional interventions targeted at prevention and early detection are essential.

FinChildren Register: National monitoring of child and adolescent health and well-being in Finland

Background

Comprehensive and up-to-date data on child and adolescent health and well-being is essential for monitoring, service development and decision-making. Although nearly all children and adolescents in Finland attend annual health check-ups at child health clinics and school healthcare, the utilization of collected data has been limited. The objective is to produce timely and representative information on the health and well-being of children, adolescents and their families based on routinely collected register data.

Methods

Data are collected from health check-ups performed at child health clinics and school health care. Recorded data are transferred through patient information systems to the Register of Primary Health Care Visits. The data can be linked to other national registers with personal identity codes. The first phase aimed to evaluate the availability and quality of register-based data through inspection of data coverage on height and weight data of children and adolescents aged 2 to 16 years.

Results

In 2018, the coverage of height and weight data ranged from 0% to 100% between municipalities depending on age group. Results were published through an interactive map application and municipality-specific summaries by gender and age group at national and municipality levels. The data enabled reporting up-to-date results on the prevalence of child and adolescent overweight and obesity in Finland.

Conclusions

Data from health check-ups form an excellent database for monitoring child and adolescent health and well-being in Finland. The challenges of utilizing register data are mainly caused by difficulties in data transfer from patient information systems resulting in insufficient data coverage. Publishing local-level reports on data coverage as well as on the results promotes data availability and quality while enabling evaluation of actions needed for promoting the health and welfare of children and their families.

Size-dependent influence of NOx on the growth rates of organic aerosol particles

Atmospheric new-particle formation (NPF) affects climate by contributing to a large fraction of the cloud condensation nuclei (CCN). Highly oxygenated organic molecules (HOMs) drive the early particle growth and therefore substantially influence the survival of newly formed particles to CCN. Nitrogen oxide (NOx) is known to suppress the NPF driven by HOMs, but the underlying mechanism remains largely unclear. Here, we examine the response of particle growth to the changes of HOM formation caused by NOx. We show that NOx suppresses particle growth in general, but the suppression is rather nonuniform and size dependent, which can be quantitatively explained by the shifted HOM volatility after adding NOx. By illustrating how NOx affects the early growth of new particles, a critical step of CCN formation, our results help provide a refined assessment of the potential climatic effects caused by the diverse changes of NOx level in forest regions around the globe.

Lentiviral interferon with immune checkpoint blockade: A novel method for gene therapy in bladder cancer

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Background: Gene therapy for bladder cancer (BLCA) is rapidly evolving. We reported that intravesical adenoviral interferon-alpha (Ad-IFNα) produced a complete response in 35% of patients with BCG-unresponsive BLCA enrolled in a Phase II trial. Lentivirus (LV) is another potential vector for intravesical delivery of IFNα. LV can infect non-dividing cells and integrate into the host’s genome, making it more efficient gene delivery vectors. As treatment with IFN upregulates checkpoint inhibitors, we also wanted to investigate the role of checkpoint inhibitors with and without IFN gene therapy. Methods: Murine BLCA cell lines were transduced in-vitro with LV-IFNα (MOI 2:1). IFNα levels were measured by ELISA. Cell viability was assessed using Trypan blue dye exclusion. qPCR was used to identify expression of IFNα target genes. A LV-βGalactosidase reporter construct was delivered intravesically, and urinary IFNα levels were measured in mice treated with LV-IFNα or control virus to assess gene transfer. To assess survival benefit, the MB49 intravesical tumor model and p53+/- C57/B6 mouse model were employed. We also assessed the role of combination therapy with immune checkpoint blockade using PD1 antibody using our MB49 intravesical model. Results: Efficient LV-IFNα transduction of BLCA cells resulted in increased expression of IFNα and its target genes and reduced cell viability vs. controls (p<0.001). Mechanistically, TRAIL dependent cytotoxicity in the LV-IFNα cells was rescued by Caspase8 inhibition. Urinary IFNα levels were elevated in mice receiving LV-IFNα compared with control virus. Overall survival improved in the MB49 model and BBN model in treated mice. LV-IFN induced intratumoral CD8+ T cell infiltration, high expression of PD-L1, and inhibited angiogenesis in BBN model whereas in the MB49 tumor response was mediated by TRAIL. Combination therapy with PD1 resulted in further improved survival. Conclusions: LV-IFNα effectively upregulated IFNα target genes, was cytotoxic to murine BLCA cells, and improved the survival in mouse models. Combining it with PD1 therapy appears to further improve survival.

Axon Guidance-Related Factor FLRT3 Regulates VEGF-Signaling and Endothelial Cell Function

Vascular endothelial growth factors (VEGFs) are key mediators of endothelial cell (EC) function in angiogenesis. Emerging knowledge also supports the involvement of axon guidance-related factors in the regulation of angiogenesis and vascular patterning. In the current study, we demonstrate that fibronectin and leucine-rich transmembrane protein-3 (FLRT3), an axon guidance-related factor connected to the regulation of neuronal cell outgrowth and morphogenesis but not to VEGF-signaling, was upregulated in ECs after VEGF binding to VEGFR2. We found that FLRT3 exhibited a transcriptionally paused phenotype in non-stimulated human umbilical vein ECs. After VEGF-stimulation its nascent RNA and mRNA-levels were rapidly upregulated suggesting that the regulation of FLRT3 expression is mainly occurring at the level of transcriptional elongation. Blockage of FLRT3 by siRNA decreased survival of ECs and their arrangement into capillary-like structures but enhanced cell migration and wound closure in wound healing assay. Bifunctional role of FLRT3 in repulsive vs. adhesive cell signaling has been already detected during embryogenesis and neuronal growth, and depends on its interactions either with UNC5B or another FLRT3 expressed by adjacent cells. In conclusion, our findings demonstrate that besides regulating neuronal cell outgrowth and morphogenesis, FLRT3 has a novel role in ECs via regulating VEGF-stimulated EC-survival, migration, and tube formation. Thus, FLRT3 becomes a new member of the axon guidance-related factors which participate in the VEGF-signaling and regulation of the EC functions.

Lentiviral interferon: A novel method for gene therapy in bladder cancer

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Background: Gene therapy for bladder cancer (BLCA) is rapidly evolving. We reported that intravesical adenoviral interferon-alpha (Ad-IFNα) produced a complete response in 35% of patients with BCG-unresponsive BLCA enrolled in a Phase II trial. Lentivirus (LV) is another potential vector for intravesical delivery of IFNα. Unlike the adenovirus, LV can infect non-dividing cells and integrate into the host’s genome, making it one of the most efficient gene delivery vectors. The objective of this study was to investigate lentiviral interferon-alpha (LV-IFNα) BLCA gene therapy in preclinical models. Methods: Murine BLCA cell lines were transduced in-vitro with LV-IFNα using a multiplicity of infection (MOI) of 2:1. IFNα levels were measured by ELISA. Cell viability was assessed using Trypan blue dye exclusion. qPCR was used to identify expression of IFNα target genes. A LV-βGalactosidase reporter construct was delivered intravesically, and urinary IFNα levels were measured in mice treated with LV-IFNα or control virus to assess gene transfer. To assess survival benefit, p53+/- C57/B6 mice were exposed to N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) to induce CIS and then treated with LV-IFNα or control virus, and sacrificed when moribund. Results: Efficient LV-IFNα transduction of BLCA cells was observed at an MOI of 2:1, resulting in increased expression of IFNα and its target genes PDL-1, TRAIL, and IRF7 (p<0.001), and reduced cell viability vs. controls (p<0.001). Mechanistically, TRAIL dependent cytotoxicity in the LV-IFNα cells was rescued by Caspase 8 inhibition. βGal expression confirmed efficient transduction of murine urothelium. Urinary IFNα levels were elevated in mice receiving LV-IFNα compared with control virus. BBN mice treated with LV-IFNα had longer overall survival than mice treated with control virus (p=0.04). LV-IFNα induced intratumoral CD8+ T cell infiltration, high expression of PD-L1, and inhibited angiogenesis. Conclusions: LV-IFNα effectively upregulated IFNα target genes, was cytotoxic to murine BLCA cells, and improved the survival of BBN tumor-bearing mice. LV appears to be a promising vector for intravesical gene delivery.

Long Non-Coding RNA Modulation of VEGF-A during Hypoxia

The role and function of long non-coding RNAs (lncRNAs) in modulating gene expression is becoming apparent. Vascular endothelial growth factor A (VEGF-A) is a key regulator of blood vessel formation and maintenance making it a promising therapeutic target for activation in ischemic diseases. In this study, we uncover a functional role for two antisense VEGF-A lncRNAs, RP1-261G23.7 and EST AV731492, in transcriptional regulation of VEGF-A during hypoxia. We find here that both lncRNAs are polyadenylated, concordantly upregulated with VEGF-A, localize to the VEGF-A promoter and upstream elements in a hypoxia dependent manner either as a single-stranded RNA or DNA bound RNA, and are associated with enhancer marks H3K27ac and H3K9ac. Collectively, these data suggest that VEGF-A antisense lncRNAs, RP1-261G23.7 and EST AV731492, function as VEGF-A promoter enhancer-like elements, possibly by acting as a local scaffolding for proteins and also small RNAs to tether.

Snake venom VEGF Vammin induces a highly efficient angiogenic response in skeletal muscle via VEGFR-2/NRP specific signaling

Vascular Endothelial Growth Factors (VEGFs) are promising molecules for the treatment of ischemic diseases by pro-angiogenic therapy. Snake venom VEGFs are a novel subgroup with unique receptor binding profiles and as such are potential new therapeutic agents. We determined the ligand-receptor interactions, gene regulation and angiogenic properties of Vipera ammodytes venom VEGF, Vammin, and compared it to the canonical angiogenic factor VEGF-A to evaluate the use of Vammin for therapeutic angiogenesis. Vammin efficiently induced VEGFR-2 mediated proliferation and expression of genes associated with proliferation, migration and angiogenesis. VEGF-A₁₆₅ and especially VEGF-A₁₀₉ induced less pronounced effects. Vammin regulates a number of signaling pathways by inducing the expression of NR4A family nuclear receptors and regulators of calcium signaling and MAP kinase pathways. Interestingly, MARC1, which encodes an enzyme discovered to catalyze reduction of nitrate to NO, was identified as a novel VEGFR-2 regulated gene. In rabbit skeletal muscle adenoviral delivery of Vammin induced prominent angiogenic responses. Both the vector dose and the co-receptor binding of the ligand were critical parameters controlling the type of angiogenic response from sprouting angiogenesis to vessel enlargement. Vammin induced VEGFR-2/NRP-1 mediated signaling more effectively than VEGF-A, consequently it is a promising candidate for development of pro-angiogenic therapies.