A systematic review of immunosuppressive protocols used in AAV gene therapy for monogenic disorders.

The emergence of adeno-associated virus (AAV)-based gene therapy has brought hope to patients with severe monogenic disorders. However, immune responses to AAV vectors and transgene products present challenges that require effective immunosuppressive strategies. This systematic review focuses on the immunosuppressive protocols used in 38 clinical trials and 35 real-world studies, considering a range of monogenic diseases, AAV serotypes, and administration routes. The review underscores the need for a deeper understanding of immunosuppressive regimens to enhance the safety and effectiveness of AAV-based gene therapy. Characterizing the immunological responses associated with various gene therapy treatments is crucial for optimizing treatment protocols and ensuring the safety and efficacy of forthcoming gene therapy interventions. Further research and understanding of the impact of immunosuppression on disease, therapy, and route of administration will contribute to the development of more effective and safer gene therapy approaches in the future.

Alterations in chromatin at antigen receptor loci define lineage progression during B lymphopoiesis.

Developing lymphocytes diversify their antigen receptor (AgR) loci by variable (diversity) joining (V[D]J) recombination. Here, using the micrococcal nuclease (MNase)-based chromatin accessibility (MACC) assay with low-cell count input, we profile both small-scale (kilobase) and large-scale (megabase) changes in chromatin accessibility and nucleosome occupancy in primary cells during lymphoid development, tracking the changes as different AgR loci become primed for recombination. The three distinct chromatin structures identified in this work define unique features of immunoglobulin H (IgH), Igκ, and T cell receptor-α (TCRα) loci during B lymphopoiesis. In particular, we find locus-specific temporal changes in accessibility both across megabase-long AgR loci and locally at the recombination signal sequences (RSSs). These changes seem to be regulated independently and can occur prior to lineage commitment. Large-scale changes in chromatin accessibility occur without significant change in nucleosome density and represent key features of AgR loci not previously described. We further identify local dynamic repositioning of individual RSS-associated nucleosomes at IgH and Igκ loci while they become primed for recombination during B cell commitment. These changes in chromatin at AgR loci are regulated in a locus-, lineage-, and stage-specific manner during B lymphopoiesis, serving either to facilitate or to impose a barrier to V(D)J recombination. We suggest that local and global changes in chromatin openness in concert with nucleosome occupancy and placement of histone modifications facilitate the temporal order of AgR recombination. Our data have implications for the organizing principles that govern assembly of these large loci as well as for mechanisms that might contribute to aberrant V(D)J recombination and the development of lymphoid tumors.

Regulated large-scale nucleosome density patterns and precise nucleosome positioning correlate with V(D)J recombination.

We show that the physical distribution of nucleosomes at antigen receptor loci is subject to regulated cell type-specific and lineage-specific positioning and correlates with the accessibility of these gene segments to recombination. At the Ig heavy chain locus (IgH), a nucleosome in pro-B cells is generally positioned over each IgH variable (VH) coding segment, directly adjacent to the recombination signal sequence (RSS), placing the RSS in a position accessible to the recombination activating gene (RAG) recombinase. These changes result in establishment of a specific chromatin organization at the RSS that facilitates accessibility of the genomic DNA for the RAG recombinase. In contrast, in mouse embryonic fibroblasts the coding segment is depleted of nucleosomes, which instead cover the RSS, thereby rendering it inaccessible. Pro-T cells exhibit a pattern intermediate between pro-B cells and mouse embryonic fibroblasts. We also find large-scale variations of nucleosome density over hundreds of kilobases, delineating chromosomal domains within IgH, in a cell type-dependent manner. These findings suggest that developmentally regulated changes in nucleosome location and occupancy, in addition to the known chromatin modifications, play a fundamental role in regulating V(D)J recombination. Nucleosome positioning-which has previously been observed to vary locally at individual enhancers and promoters-may be a more general mechanism by which cells can regulate the accessibility of the genome during development, at scales ranging from several hundred base pairs to many kilobases.

Novel photosensitisers derived from pyropheophorbide-a: uptake by cells and photodynamic efficiency in vitro.

Photodynamic Therapy (PDT) is a minimally invasive procedure used for treating a range of neoplastic diseases, which utilises combined action of light and a PDT drug called a photosensitiser. The efficiency of this treatment depends crucially on the properties of the photosensitiser used, namely on its efficient uptake by cells or by the surrounding vasculature, intracellular localisation, minimal dark toxicity and substantial phototoxicity. In this report we compare the spectroscopic properties, cell uptake and in vitro phototoxicity of two novel hydrophilic photosensitisers derived from pyropheophorbide-a (PPa). Both new photosensitisers have the potential to form bioconjugates with antibody fragments for targeted PDT. We find that the photophysical properties of both new photosensitisers are favourable compared to the parent PPa, including enhanced absorption in the red spectral region and substantial singlet oxygen quantum yields. Both molecules show efficient cellular uptake, but display a different intracellular localisation. Both new photosensitisers exhibit no significant dark-toxicity at concentrations of up to 100 microM. The phototoxicity of the two photosensitisers is strikingly different, with one derivative being 13 times more efficient than the parent PPa and another derivative being 18 times less efficient in SKOV3 ovarian cancer cells. We investigate the reasons behind such drastic differences in phototoxicity using confocal fluorescence microscopy and conclude that intracellular localisation is a crucial factor in the photodynamic efficiency of pheophorbide derivatives. These studies highlight the underlying factors behind creating more potent photosensitisers through synthetic manipulation.

Surveillance of antimicrobial resistance and evolving microbial populations in Vermont: 2011-2018.

OBJECTIVE: This study presents trends in organism isolation and antimicrobial resistance in routine microbiology test results from acute-care hospital microbiology laboratories in Vermont. METHODS: Organism identifications and antimicrobial susceptibility test results were captured from acute-care hospital laboratories to monitor geographic and temporal trends in resistance and emerging microbial threats with the free WHONET software. RESULTS: Data were provided from 12 acute care hospital laboratories from 2011 through 2018 for 318,833 isolates from 148,994 patients (70% female, 74% outpatient, and 63% urine). Significant differences (p < 0.05) in age, gender, and antimicrobial susceptibility results (e.g. Escherichia coli and levofloxacin) between outpatient and inpatient isolates were identified with temporal increases in certain species (e.g. Aerococcus urinae) and resistance (e.g. Streptococcus pneumoniae and erythromycin). The use of multi-resistance phenotypes demonstrated significant heterogeneity (p < 0.05) in MRSA strains between facilities, for example Staphylococcus aureus resistant to six priority antimicrobials were found in no critical access hospitals (fewer than 25 inpatient beds) but in all non-critical access hospitals. CONCLUSIONS: Comprehensive electronic surveillance of antimicrobial resistance utilizing routine clinical microbiology data with free software tools offers early recognition and tracking of emerging community and healthcare resistance threats at the local and state level.

Low-Input MNase Accessibility of Chromatin (Low-Input MACC).

An understanding of the dynamic structural properties of chromatin requires techniques that allow the profiling of regions of both open and closed chromatin as well as the assessment of nucleosome occupancy. The recently developed MNase accessibility (MACC) technique allows for the simultaneous measurement of chromatin opening and compaction, as well as nucleosome occupancy, on a genome-wide scale in a single assay. This article presents a low-input MACC procedure that considerably extends the utility of the original MACC assay. Low-input MACC generates high-quality data using very low cell numbers (as few as 50 cells per titration point), making it ideal for samples obtained after fluorescence-activated cell sorting or dissection, or in clinical settings. Moreover, low-input MACC has significantly improved several steps of the initial method, offering a more rapid and robust methodology. © 2019 by John Wiley & Sons, Inc.

Correction to: Reactivation of TAp73 tumor suppressor by protoporphyrin IX, a metabolite of aminolevulinic acid, induces apoptosis in TP53-deficient cancer cells.

[This corrects the article DOI: 10.1186/s13008-018-0043-3.].

Reactivation of TAp73 tumor suppressor by protoporphyrin IX, a metabolite of aminolevulinic acid, induces apoptosis in TP53-deficient cancer cells.

BACKGROUND: The p73 protein is a tumor suppressor that shares structural and functional similarity with p53. p73 is expressed in two major isoforms; the TA isoform that interacts with p53 pathway, thus acting as tumor suppressor and the N-terminal truncated ΔN isoform that inhibits TAp73 and p53 and thus, acts as an oncogene. RESULTS: By employing a drug repurposing approach, we found that protoporphyrin IX (PpIX), a metabolite of aminolevulinic acid applied in photodynamic therapy of cancer, stabilizes TAp73 and activates TAp73-dependent apoptosis in cancer cells lacking p53. The mechanism of TAp73 activation is via disruption of TAp73/MDM2 and TAp73/MDMX interactions and inhibition of TAp73 degradation by ubiquitin ligase Itch. Finally, PpIX showed potent antitumor effect and inhibited the growth of xenograft human tumors in mice. CONCLUSION: Our findings may in future contribute to the successful repurposing of PpIX into clinical practice.

TOX Regulates Growth, DNA Repair, and Genomic Instability in T-cell Acute Lymphoblastic Leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy of thymocytes. Using a transgenic screen in zebrafish, thymocyte selection-associated high mobility group box protein (TOX) was uncovered as a collaborating oncogenic driver that accelerated T-ALL onset by expanding the initiating pool of transformed clones and elevating genomic instability. TOX is highly expressed in a majority of human T-ALL and is required for proliferation and continued xenograft growth in mice. Using a wide array of functional analyses, we uncovered that TOX binds directly to KU70/80 and suppresses recruitment of this complex to DNA breaks to inhibit nonhomologous end joining (NHEJ) repair. Impaired NHEJ is well known to cause genomic instability, including development of T-cell malignancies in KU70- and KU80-deficient mice. Collectively, our work has uncovered important roles for TOX in regulating NHEJ by elevating genomic instability during leukemia initiation and sustaining leukemic cell proliferation following transformation.Significance: TOX is an HMG box-containing protein that has important roles in T-ALL initiation and maintenance. TOX inhibits the recruitment of KU70/KU80 to DNA breaks, thereby inhibiting NHEJ repair. Thus, TOX is likely a dominant oncogenic driver in a large fraction of human T-ALL and enhances genomic instability. Cancer Discov; 7(11); 1336-53. ©2017 AACR.This article is highlighted in the In This Issue feature, p. 1201.

Evolution of p53 transactivation specificity through the lens of a yeast-based functional assay.

Co-evolution of transcription factors (TFs) with their respective cis-regulatory network enhances functional diversity in the course of evolution. We present a new approach to investigate transactivation capacity of sequence-specific TFs in evolutionary studies. Saccharomyces cerevisiae was used as an in vivo test tube and p53 proteins derived from human and five commonly used animal models were chosen as proof of concept. p53 is a highly conserved master regulator of environmental stress responses. Previous reports indicated conserved p53 DNA binding specificity in vitro, even for evolutionary distant species. We used isogenic yeast strains where p53-dependent transactivation was measured towards chromosomally integrated p53 response elements (REs). Ten REs were chosen to sample a wide range of DNA binding affinity and transactivation capacity for human p53 and proteins were expressed at two levels using an inducible expression system. We showed that the assay is amenable to study thermo-sensitivity of frog p53, and that chimeric constructs containing an ectopic transactivation domain could be rapidly developed to enhance the activity of proteins, such as fruit fly p53, that are poorly effective in engaging the yeast transcriptional machinery. Changes in the profile of relative transactivation towards the ten REs were measured for each p53 protein and compared to the profile obtained with human p53. These results, which are largely independent from relative p53 protein levels, revealed widespread evolutionary divergence of p53 transactivation specificity, even between human and mouse p53. Fruit fly and human p53 exhibited the largest discrimination among REs while zebrafish p53 was the least selective.

Cooperative interactions between p53 and NFκB enhance cell plasticity.

The p53 and NFκB sequence-specific transcription factors play crucial roles in cell proliferation and survival with critical, even if typically opposite, effects on cancer progression. To investigate a possible crosstalk between p53 and NFκB driven by chemotherapy-induced responses in the context of an inflammatory microenvironment, we performed a proof of concept study using MCF7 cells. Transcriptome analyses upon single or combined treatments with doxorubicin (Doxo, 1.5µM) and the NFκB inducer TNF-alpha (TNFα, 5ng/ml) revealed 432 up-regulated (log2 FC> 2), and 390 repressed genes (log2 FC< -2) for the Doxo+TNFα treatment. 239 up-regulated and 161 repressed genes were synergistically regulated by the double treatment. Annotation and pathway analyses of Doxo+TNFα selectively up-regulated genes indicated strong enrichment for cell migration terms. A panel of genes was examined by qPCR coupled to p53 activation by Doxo, 5-Fluoruracil and Nutlin-3a, or to p53 or NFκB inhibition. Transcriptome data were confirmed for 12 of 15 selected genes and seven (PLK3, LAMP3, ETV7, UNC5B, NTN1, DUSP5, SNAI1) were synergistically up-regulated after Doxo+TNFα and dependent both on p53 and NFκB. Migration assays consistently showed an increase in motility for MCF7 cells upon Doxo+TNFα. A signature of 29 Doxo+TNFα highly synergistic genes exhibited prognostic value for luminal breast cancer patients, with adverse outcome correlating with higher relative expression. We propose that the crosstalk between p53 and NFκB can lead to the activation of specific gene expression programs that may impact on cancer phenotypes and potentially modify the efficacy of cancer therapy.

Interaction between p53 and estradiol pathways in transcriptional responses to chemotherapeutics.

Estrogen receptors (ERs) and p53 can interact via cis-elements to regulate the angiogenesis-related VEGFR-1 (FLT1) gene, as we reported previously. Here, we address cooperation between these transcription factors on a global scale. Human breast adenocarcinoma MCF7 cells were exposed to single or combinatorial treatments with the chemotherapeutic agent doxorubicin and the ER ligand 17ß-estradiol (E2). Whole-genome transcriptome changes were measured by expression microarrays. Nearly 200 differentially expressed genes were identified that showed limited responsiveness to either doxorubicin treatment or ER ligand alone but were upregulated in a greater than additive manner following combined treatment. Based on exposure to 5-fuorouracil and nutlin-3a, the combined responses were treatment-specific. Among 16 genes chosen for validation using quantitative real-time PCR, seven (INPP5D, TLR5, KRT15, EPHA2, GDNF, NOTCH1, SOX9) were confirmed to be novel direct targets of p53, based on responses in MCF7 cells silenced for p53 or cooperative targets of p53 and ER. Promoter pattern searches and chromatin IP experiments for the INPP5D, TLR5, KRT15 genes supported direct, cis-mediated p53 and/or ER regulation through canonical and noncanonical p53 and ER response elements. Collectively, we establish that combinatorial activation of p53 and ER can induce novel gene expression programs that have implications for cell-cell communications, adhesion, cell differentiation, development and inflammatory responses as well as cancer treatments.

p53 transactivation and the impact of mutations, cofactors and small molecules using a simplified yeast-based screening system.

BACKGROUND: The p53 tumor suppressor, which is altered in most cancers, is a sequence-specific transcription factor that is able to modulate the expression of many target genes and influence a variety of cellular pathways. Inactivation of the p53 pathway in cancer frequently occurs through the expression of mutant p53 protein. In tumors that retain wild type p53, the pathway can be altered by upstream modulators, particularly the p53 negative regulators MDM2 and MDM4. METHODOLOGY/PRINCIPAL FINDINGS: Given the many factors that might influence p53 function, including expression levels, mutations, cofactor proteins and small molecules, we expanded our previously described yeast-based system to provide the opportunity for efficient investigation of their individual and combined impacts in a miniaturized format. The system integrates i) variable expression of p53 proteins under the finely tunable GAL1,10 promoter, ii) single copy, chromosomally located p53-responsive and control luminescence reporters, iii) enhanced chemical uptake using modified ABC-transporters, iv) small-volume formats for treatment and dual-luciferase assays, and v) opportunities to co-express p53 with other cofactor proteins. This robust system can distinguish different levels of expression of WT and mutant p53 as well as interactions with MDM2 or 53BP1. CONCLUSIONS/SIGNIFICANCE: We found that the small molecules Nutlin and RITA could both relieve the MDM2-dependent inhibition of WT p53 transactivation function, while only RITA could impact p53/53BP1 functional interactions. PRIMA-1 was ineffective in modifying the transactivation capacity of WT p53 and missense p53 mutations. This dual-luciferase assay can, therefore, provide a high-throughput assessment tool for investigating a matrix of factors that can influence the p53 network, including the effectiveness of newly developed small molecules, on WT and tumor-associated p53 mutants as well as interacting proteins.