DNA base editing corrects common Hemophilia A mutations and restores factor VIII expression in vitro and ex-vivo models

Background: Replacement and non-replacement therapies effectively control bleedings in Hemophilia A (HA) but imply lifelong interventions. The authorized gene addition therapy could provide a cure but still poses questions on durability. F8 gene correction would definitively restore factor VIII (FVIII) production, as shown in animal models through nucleases mediating homologous recombination (HR). However, low efficiency and potential off-target double-strand break (DSB) still limit HR translatability. Objectives: To correct common model single point mutations leading to severe HA through the recently developed DSB/HR-independent base (BE) and prime (PE) editing approaches. Methods: Screening for efficacy of BE/PE systems in HEK293T transiently expressing FVIII variants and validation at DNA (sequencing) and protein (ELISA; aPTT) level in stable clones. Evaluation of rescue in engineered blood outgrowth endothelial cells (BOEC) by lentiviral-mediated delivery of BE. Results and conclusions: Transient assays identified the best-performing BE/PE systems for each variant, with the highest rescue of FVIII expression (up to 25% of rFVIIIwt) for the p.R2166* and p.R2228Q mutations. In stable clones we demonstrated that the mutation reversion on DNA (∼24%) was consistent with the rescue of FVIII secretion and activity 20-30%). The lentiviral-mediated delivery of the selected BE systems was attempted in engineered BOEC harboring the p.R2166* and p.R2228Q variants, which led to an appreciable and dose-dependent rescue of secreted functional FVIII. Overall data provide the first proof-of-concept for effective BE/PE-mediated correction of HA-causing mutations, which encourage studies in mouse models to develop a personalized cure for large cohorts of patients though a single intervention

An exon-specific U1 small nuclear RNA (snRNA) strategy to correct splicing defects

A significant proportion of disease-causing mutations affect precursor-mRNA splicing, inducing skipping of the exon from the mature transcript. Using F9 exon 5, CFTR exon 12 and SMN2 exon 7 models, we characterized natural mutations associated to exon skipping in Haemophilia B, cystic fibrosis and spinal muscular atrophy (SMA), respectively, and the therapeutic splicing rescue by using U1 small nuclear RNA (snRNA). In minigene expression systems, loading of U1 snRNA by complementarity to the normal or mutated donor splice sites (5′ss) corrected the exon skipping caused by mutations at the polypyrimidine tract of the acceptor splice site, at the consensus 5′ss or at exonic regulatory elements. To improve specificity and reduce potential off-target effects, we developed U1 snRNA variants targeting non-conserved intronic sequences downstream of the 5′ss. For each gene system, we identified an exon-specific U1 snRNA (ExSpeU1) able to rescue splicing impaired by the different types of mutations. Through splicing-competent cDNA constructs, we demonstrated that the ExSpeU1-mediated splicing correction of several F9 mutations results in complete restoration of secreted functional factor IX levels. Furthermore, two ExSpeU1s for SMA improved SMN exon 7 splicing in the chromosomal context of normal cells. We propose ExSpeU1s as a novel therapeutic strategy to correct, in several human disorders, different types of splicing mutations associated with defective exon definition

Comparative Analysis Of Residual Factor VIII Expression from Recurrent F8 Nonsense Mutations Indicates that Localization in the B- domain Favours Readthrough- mediated Protein Output

Background: Nonsense mutations, inserting premature termination codons (PTCs), might undergo, with low frequency (<0.01%), spontaneous suppression (readthrough) with production of full-length proteins upon amino acid insertion at the PTC. This process, dictated by nucleotide/protein sequence features, might have implications for hemophilia A (HA) patients. Aims: To investigate residual factor VIII (FVIII) expression through complementary studies in HA patients’ plasma and exploiting a sensitive in-vitro expression platform. Methods: Detection of plasma FVIII levels (ELISA, aPTT), and expression studies (HEK293 cells) with a highly-sensitive naturally-secreted luciferase (Gaussia, GL) fused to FVIII (FVIII-GL). Results: Plasma samples from HA patients affected by six nonsense mutations (p.R446X, p.R814X, p.K1289X, p.W1726X, p.R1985X, p.R2135X) revealed traces of FVIII. Strikingly, the two B-domain variants (p.R814X, p.K1289X) showed the highest FVIII levels, suggesting a position-dependent effect. Expression studies with the FVIII-GL variants showed that those of the B-domain produced the highest luciferase activity levels, thus supporting in vivo findings. Accordingly, the predicted readthrough-deriving amino acid changes (R446W, R814W, K1289Q/Y, W1726Y, R1985W, R2135W) showed a minor impact for those affecting the B-domain. To verify further our hypothesis, the panel of F8 mutations was rationally expanded to be representative of the majority of patients with nonsense mutations (60%), including the most frequent (50% of patients) in the B-domain. Through our sensitive platform we observed that all F8 nonsense variants led to detectable luciferase activity (0.4-6%). Strikingly, when categorized in two groups (B-domain, n=21; other domains, n=26), secreted luciferase activity of B-domain variants was significantly higher (p<0.0001) as compared with variants located in the other FVIII domains. Conclusions: Our findings for the first time indicate that nonsense mutations in the B-domain, known to tolerate missense changes as those potentially arising from readthrough, are favoured in terms of readthrough-mediated protein output, which might have pathophysiological implications for HA patients

F9 Missense mutations impairing factor ix activation are associated with pleiotropic plasma phenotypes

Background: Circulating dysfunctional factor IX (FIX) might modulate distribution of infused FIX in haemophilia B (HB) patients. Recurrent substitutions at FIX activation sites (R191-R226, >300 patients) are associated with variable FIX activity and antigen (FIXag) levels. Objectives: To investigate i) expression of a complete panel of missense mutations at FIX activation sites and ii) contribution of F9 genotypes on the FIX pharmacokinetics (PK). Methods: FIXag and activity assays in plasma and after recombinant expression of FIX variants. Analysis of infused FIX PK parameters in patients (n=30), mostly enrolled in the F9 Genotype and PK HB Italian Study (GePKHIS; EudraCT ID2017-003902-42). Results: The variable FIXag amounts and good relation between biosynthesis and activity of multiple R191 variants result in graded moderate-to-mild severity of the R191C>L>P>H substitutions. Recombinant expression may predict the absence in the HB mutation database of the benign R191Q/W/K and R226K substitutions. Equivalent changes at R191/R226 produced higher FIXag levels for R226Q/W/P substitutions, as also observed in p.R226W female carrier plasma. PK analysis in patients suggested that infused FIX Alpha distribution and Beta elimination phases positively correlated with endogenous FIXag levels. Mean residence time was particularly prolonged (79.4 hrs, 95% CI 44.3-114.5) in patients (n=7) with the R191/R226 substitutions, which in regression analysis were independent predictors (β coefficient 0.699, p=0.004) of Beta half-life, potentially prolonged by the increasing over time ratio between endogenous and infused FIX. Conclusions: FIXag levels and specific features of the dysfunctional R191/R226 variants may exert pleiotropic effects both on HB patients’ phenotypes and substitutive treatment

Combined Effect of Hemostatic Gene Polymorphisms and the Risk of Myocardial Infarction in Patients with Advanced Coronary Atherosclerosis

BACKGROUND: Relative little attention has been devoted until now to the combined effects of gene polymorphisms of the hemostatic pathway as risk factors for Myocardial Infarction (MI), the main thrombotic complication of Coronary Artery Disease (CAD). The aim of this study was to evaluate the combined effect of ten common prothrombotic polymorphisms as a determinant of MI. METHODOLOGY/PRINCIPAL FINDINGS: We studied a total of 804 subjects, 489 of whom with angiographically proven severe CAD, with or without MI (n = 307; n = 182; respectively). An additive model considering ten common polymorphisms [Prothrombin 20210G>A, PAI-1 4G/5G, Fibrinogen beta -455G>A, FV Leiden and "R2", FVII -402G>A and -323 del/ins, Platelet ADP Receptor P2Y12 -744T>C, Platelet Glycoproteins Ia (873G>A), and IIIa (1565T>C)] was tested. The prevalence of MI increased linearly with an increasing number of unfavorable alleles (chi(2) for trend = 10.68; P = 0.001). In a multiple logistic regression model, the number of unfavorable alleles remained significantly associated with MI after adjustment for classical risk factors. As compared to subjects with 3-7 alleles, those with few (/=8) alleles had an increased MI risk (OR 2.49, 95%CIs 1.03-6.01). The number of procoagulant alleles correlated directly (r = 0.49, P = 0.006) with endogenous thrombin potential. CONCLUSIONS: The combination of prothrombotic polymorphisms may help to predict MI in patients with advanced CAD

Correction to: Two years later: Is the SARS-CoV-2 pandemic still having an impact on emergency surgery? An international cross-sectional survey among WSES members

Background: The SARS-CoV-2 pandemic is still ongoing and a major challenge for health care services worldwide. In the first WSES COVID-19 emergency surgery survey, a strong negative impact on emergency surgery (ES) had been described already early in the pandemic situation. However, the knowledge is limited about current effects of the pandemic on patient flow through emergency rooms, daily routine and decision making in ES as well as their changes over time during the last two pandemic years. This second WSES COVID-19 emergency surgery survey investigates the impact of the SARS-CoV-2 pandemic on ES during the course of the pandemic. Methods: A web survey had been distributed to medical specialists in ES during a four-week period from January 2022, investigating the impact of the pandemic on patients and septic diseases both requiring ES, structural problems due to the pandemic and time-to-intervention in ES routine. Results: 367 collaborators from 59 countries responded to the survey. The majority indicated that the pandemic still significantly impacts on treatment and outcome of surgical emergency patients (83.1% and 78.5%, respectively). As reasons, the collaborators reported decreased case load in ES (44.7%), but patients presenting with more prolonged and severe diseases, especially concerning perforated appendicitis (62.1%) and diverticulitis (57.5%). Otherwise, approximately 50% of the participants still observe a delay in time-to-intervention in ES compared with the situation before the pandemic. Relevant causes leading to enlarged time-to-intervention in ES during the pandemic are persistent problems with in-hospital logistics, lacks in medical staff as well as operating room and intensive care capacities during the pandemic. This leads not only to the need for triage or transferring of ES patients to other hospitals, reported by 64.0% and 48.8% of the collaborators, respectively, but also to paradigm shifts in treatment modalities to non-operative approaches reported by 67.3% of the participants, especially in uncomplicated appendicitis, cholecystitis and multiple-recurrent diverticulitis. Conclusions: The SARS-CoV-2 pandemic still significantly impacts on care and outcome of patients in ES. Well-known problems with in-hospital logistics are not sufficiently resolved by now; however, medical staff shortages and reduced capacities have been dramatically aggravated over last two pandemic years

How future surgery will benefit from SARS-COV-2-related measures: a SPIGC survey conveying the perspective of Italian surgeons

COVID-19 negatively affected surgical activity, but the potential benefits resulting from adopted measures remain unclear. The aim of this study was to evaluate the change in surgical activity and potential benefit from COVID-19 measures in perspective of Italian surgeons on behalf of SPIGC. A nationwide online survey on surgical practice before, during, and after COVID-19 pandemic was conducted in March-April 2022 (NCT:05323851). Effects of COVID-19 hospital-related measures on surgical patients' management and personal professional development across surgical specialties were explored. Data on demographics, pre-operative/peri-operative/post-operative management, and professional development were collected. Outcomes were matched with the corresponding volume. Four hundred and seventy-three respondents were included in final analysis across 14 surgical specialties. Since SARS-CoV-2 pandemic, application of telematic consultations (4.1% vs. 21.6%; p < 0.0001) and diagnostic evaluations (16.4% vs. 42.2%; p < 0.0001) increased. Elective surgical activities significantly reduced and surgeons opted more frequently for conservative management with a possible indication for elective (26.3% vs. 35.7%; p < 0.0001) or urgent (20.4% vs. 38.5%; p < 0.0001) surgery. All new COVID-related measures are perceived to be maintained in the future. Surgeons' personal education online increased from 12.6% (pre-COVID) to 86.6% (post-COVID; p < 0.0001). Online educational activities are considered a beneficial effect from COVID pandemic (56.4%). COVID-19 had a great impact on surgical specialties, with significant reduction of operation volume. However, some forced changes turned out to be benefits. Isolation measures pushed the use of telemedicine and telemetric devices for outpatient practice and favored communication for educational purposes and surgeon-patient/family communication. From the Italian surgeons' perspective, COVID-related measures will continue to influence future surgical clinical practice

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Residual factor IX expression in Hemophilia B patients with nonsense mutations: a determinant of inhibitory development?

The rationale is provided by the process of “ribosome readthrough” over nonsense mutations that, by reverting premature translation termination, would restore protein biosynthesis. Although at low rate, this process can occur spontaneously, and account for residual levels of protein that in coagulation factor disorders might have relevant pathophysiological implications. So far, we provided evidence for residual FVII and FIX levels (~1%) associated to a few nonsense changes. In the present project, through studies in vivo and in vitro, we propose to investigation on a panel of F9 nonsense mutations to verify the hypothesis that part of nonsense mutations found in severe HB patients are associated to residual FIX levels. If confirmed, we expect to assess whether these traces of FIX are related to the clinical phenotype of patients and their immunological complications. Moreover, it could suggest potential “high responders” to drugs inducing readthrough. The knowledge of “leaky” nonsense mutations, less prone to trigger immune-response, could help diagnosis and treatment. Results from this study on a limited patients’ number could boost a more extensive study in HB patients, and extended to hemophilia A

The effect of the chemical chaperone 4-phenylbutyrate on secretion and activity of the p.Q160R missense variant of coagulation factor FVII.

Background: Congenital coagulation factor (F) VII defciency is a rare bleeding disorder caused by mutations in the F7 gene. The missense factor FVII variant p.Q160R is the disease-causing mutation in all Norwegian FVII defcient patients and results in reduced biological activity and antigen levels of FVII in patient plasma. Previous in vitro studies on this variant demonstrated impaired intracellular trafcking and reduced secretion, possibly due to protein misfolding. The aim of the study was therefore to assess the impact of chemical chaperones on cellular processing and secretion of this variant using a cell model based on overexpression of the recombinant protein. Results: Through screening of compounds, we identifed 4-phenylbutyrate (4-PBA) to increase the secretion of recombinant (r) FVII-160R by~2.5-fold. Additionally, treatment with 4-PBA resulted in a modest increase in specifc biological activity. Intracellular localization studies revealed that upon treatment with 4-PBA, rFVII-160R was secreted through Golgi and Golgi reassembly-stacking protein (GRASP)-structures. Conclusions: The present study demonstrates that the chemical chaperone 4-PBA, restores intracellular trafcking and increases the secretion of a missense FVII variant with functional properties in the extrinsic coagulation pathwa