Targeted, programmable, and precise tandem duplication in the mammalian genome

Tandem duplications are frequent structural variations of the genome and play important roles in genetic disease and cancer. However, interpreting the phenotypic consequences of tandem duplications remains challenging, in part owing to the lack of genetic tools to model such variations. Here, we developed a strategy, tandem duplication via prime editing (TD-PE), to create targeted, programmable, and precise tandem duplication in the mammalian genome. In this strategy, we design a pair of in trans prime editing guide RNAs (pegRNAs) for each targeted tandem duplication, which encode the same edits but prime the single-stranded DNA (ssDNA) extension in opposite directions. The reverse transcriptase (RT) template of each extension is designed homologous to the target region of the other single guide RNA (sgRNA) to promote the reannealing of the edited DNA strands and the duplication of the fragment in between. We showed that TD-PE produced robust and precise in situ tandem duplications of genomic fragments ranging from ∼50 bp to ∼10 kb, with a maximal efficiency up to 28.33%. By fine-tuning the pegRNAs, we achieved simultaneous targeted duplication and fragment insertion. Finally, we successfully produced multiple disease-relevant tandem duplications, showing the general utility of TD-PE in genetic research.

Risk factors, clinical features, and outcomes of premature acute myocardial infarction

AIMS

To investigate the risk factors, clinical features, and prognostic factors of patients with premature acute myocardial infarction (AMI).

MATERIALS AND METHODS

A retrospective cohort study of patients with AMI included in data from the West China Hospital of Sichuan University from 2011 to 2019 was divided into premature AMI (aged < 55 years in men and < 65 years in women) and non-premature AMI. Patients' demographics, laboratory tests, Electrocardiography (ECG), cardiac ultrasound, and coronary angiography reports were collected. All-cause death after incident premature MI was enumerated as the primary endpoint.

RESULTS

Among all 8,942 AMI cases, 2,513 were premature AMI (79.8% men). Compared to the non-premature AMI group, risk factors such as smoking, dyslipidemia, overweight, obesity, and a family history of coronary heart disease (CHD) were more prevalent in the premature AMI group. The cumulative survival rate of patients in the premature AMI group was significantly better than the non-premature AMI group during a mean follow-up of 4.6 years (HR = 0.27, 95% CI 0.22-0.32, p < 0.001). Low left ventricular ejection fraction (LVEF) (Adjusted HR 3.00, 95% CI 1.85-4.88, P < 0.001), peak N-terminal pro-B-type natriuretic peptide (NT-proBNP) level (Adjusted HR 1.34, 95% CI 1.18-1.52, P < 0.001) and the occurrence of in-hospital major adverse cardiovascular and cerebrovascular events (MACCEs) (Adjusted HR 2.36, 95% CI 1.45-3.85, P = 0.001) were predictors of poor prognosis in premature AMI patients.

CONCLUSION

AMI in young patients is associated with unhealthy lifestyles such as smoking, dyslipidemia, and obesity. Low LVEF, elevated NT-proBNP peak level, and the occurrence of in-hospital MACCEs were predictors of poor prognosis in premature AMI patients.

Global Burden Attributable to High Low-Density Lipoprotein-Cholesterol From 1990 to 2019

Background

High low-density lipoprotein-cholesterol (LDL-C) is a public health issue contributing to ischemic heart disease (IHD) and stroke.

Method

In this ecological study, we collected summary exposure values (SEVs), deaths, disability-adjusted life of years (DALYs), and Social Demographic Index (SDI) of high LDL-C from 1990 to 2019 using the query tool from the Global Burden of Disease (GBD) Collaborative Network. Outcomes include SEVs, deaths, and DALYs attributable to high LDL-C stratified by sex, age, region, SDI, countries, and territories. Estimated annual percentage changes (EAPCs) were applied to estimate annual trends of changes in these outcomes. We applied the weighted segmented regression with break-point estimation to detect the linear piecewise relationship between SDI and high LDL-C disease burden.

Results

Globally, 3.00 million (95% uncertainty interval [UI], 2.35–3.76 million) people in 1990 and 4.40 million (95% UI, 3.30–5.65 million) people died from high LDL-C in 2019. The absolute annual burden from deaths and DALYs attributed to high LDL-C increased by 46% (95% UI, 35–56%) and 41% (95% UI, 31–50%) from 1990 to 2019. The age-standardized SEV, death, and DALY was decreased by 9% (95% UI, −11 to −8%), 37% (95% UI, −41−33%), and 32% (95% UI, −37 to −28%), respectively, during the study period. There was a negative association between SDI and high LDL-C-related age-standardized death and DALY rates when SDI surpassed 0.71 and 0.71, respectively.

Conclusion

Although the overall age-standardized burden of high LDL-C is controlled in the past 30 years, it remains increasing in moderate SDI countries, and decreasing trends are disappearing in high SDI countries. New challenges require new actions stratified by countries with different SDI levels.

Strongyloidiasis in a Patient Diagnosed by Metagenomic Next-Generation Sequencing: A Case Report

Background

Strongylodiasis may be asymptomatic or cause mild gastrointestinal symptoms, and may be a fatal disseminated disease or Strongyloides hyperinfection syndrome. Non-specific clinical manifestations, such as pneumonia and gastroenteritis, pose a diagnostic dilemma.

Case Presentation

We report a case of a 67-year-old Chinese male who presented with abdominal pain, fever, headache, vomiting, constipation, and slight cough with sputum for nearly 2 months. He had been in good health and had no history of glucocorticoid use. He was diagnosed with enterococcal meningitis and intestinal obstruction at a local hospital and improved after treatment with vancomycin, but symptoms of headache and abdominal pain soon recurred. The metagenomic next-generation sequencing (mNGS) of the cerebrospinal fluid using Illumina X10 sequencer revealed seven sequence reads matching Strongyloides stercoralis. Strongyloidiasis was suspected. Microscopic examination of gastric fluid revealed the presence of S. stercoralis larvae, which was confirmed by PCR to amplify both S. stercoralis ribosomal DNA gene and mitochondrial cytochrome c oxidase subunit 1 gene and sequencing amplicons. Strongyloidiasis was diagnosed. Albendazole (400 mg, twice daily) was used, and the patient recovered gradually.

Conclusion

mNGS may be a useful tool for detecting uncommon infectious disease. The case would help clinicians to raise awareness of strongyloidiasis in non-endemic areas and reduce fatality.

Programmable Unlocking Nano-Matryoshka-CRISPR Precisely Reverses Immunosuppression to Unleash Cascade Amplified Adaptive Immune Response

Immune checkpoint blockade (ICB) is an attractive option in cancer therapy, but its efficacy is still less than expected due to the transient and incomplete blocking and the low responsiveness. Herein, an unprecedented programmable unlocking nano-matryoshka-CRISPR system (PUN) targeting programmed cell death ligand 1 (PD-L1) and protein tyrosine phosphatase N2 (PTPN2) is fabricated for permanent and complete and highly responsive immunotherapy. While PUN is inert at normal physiological conditions, enzyme-abundant tumor microenvironment and preternatural intracellular oxidative stress sequentially trigger programmable unlocking of PUN to realize a nano-matryoshka-like release of CRISPR/Cas9. The successful nucleus localization of CRISPR/Cas9 ensures the highly efficient disruption of PD-L1 and PTPN2 to unleash cascade amplified adaptive immune response via revoking the immune checkpoint effect. PD-L1 downregulation in tumor cells not only disrupts PD-1/PD-L1 interaction to attenuate the immunosurveillance evasion but also spurs potent immune T cell responses to enhance adaptive immunity. Synchronously, inhibition of JAK/STAT pathway is relieved by deleting PTPN2, which promotes tumor susceptibility to CD8+ T cells depending on IFN-γ, thus further amplifying adaptive immune responses. Combining these advances together, PUN exhibits optimal antitumor efficiency and long-term immune memory with negligible toxicity, which provides a promising alternative to current ICB therapy.

Injectable Thermosensitive Hydrogel Containing Erlotinib-Loaded Hollow Mesoporous Silica Nanoparticles as a Localized Drug Delivery System for NSCLC Therapy

Erlotinib (ERT), oral administration agents, is one of the most pivotal targeted drugs in the treatment of non-small cell lung cancer (NSCLC); however, its poor solubility, low oral bioavailability, and capricious toxicity limit broader clinical applications. In this paper, a novel injectable matrix is prepared based on hollow mesoporous silica nanoparticles (HMSNs) and thermosensitive poly(d,l-lactide)-poly(ethylene glycol)-poly(d,l-lactide) (PDLLA-PEG-PDLLA, PLEL) hydrogel to encapsulate and localize the sustained release of ERT for improved efficacy against NSCLC. The test-tube-inversion method shows that this ERT-loaded hydrogel composite (ERT@HMSNs/gel) presents as an injectable flowing solution under room temperature and transfers into a physically crosslinked non-flowing gel structure at physiological temperature.The ERT@HMSNs/gel composite shows a much longer intratumoral and peritumoral drug retention by in vivo imaging study. Notably, this injectable drug delivery system (DDS) provides an impressive balance between antitumor efficacy and systemic safety in a mice xenograft model. The novel ERT loaded HMSNs/gel system may be a promising candidate for the in situ treatment of NSCLC. Moreover, this study provides a prospective platform for the design and fabrication of a nano-scaled delivery system for localized anticancer therapies.

A 3D-Printed Self-Adhesive Bandage with Drug Release for Peripheral Nerve Repair

Peripheral nerve injury is a common disease that often causes disability and challenges surgeons. Drug-releasable biomaterials provide a reliable tool to regulate the nerve healing-associated microenvironment for nerve repair. Here, a self-adhesive bandage is designed that can form a wrap surrounding the injured nerve to promote nerve regeneration and recovery. Via a 3D printing technique, the bandage is prepared with a special structure and made up of two different hydrogel layers that can adhere to each other by a click reaction. The nanodrug is encapsulated in one layer with a grating structure. Wrapping the injured nerve, the grating layer of the bandage is closed to the injured site. The drug can be mainly released to the inner area of the wrap to promote the nerve repair by improving the proliferation and migration of Schwann cells. In this study, the bandage is used to assist the neurorrhaphy for the treatment of complete sciatic nerve transection without obvious defect in rats. Results indicate that the self-adhesive capacity can simplify the installation process and the drug-loaded bandage can promote the repairing of injured nerves. The demonstrated 3D-printed self-adhesive bandage has potential application in assisting the neurorrhaphy for nerve repair.

Engineering chromosome region maintenance 1 fragments that bind to nuclear export signals

Chromosome region maintenance 1 (CRM1) exports nuclear export signal (NES) containing cargos from nucleus to cytoplasm and plays critical roles in cancer and viral infections. Biochemical and biophysical studies on this protein were often obstructed by its low purification yield and stability. With the help of PROSS server and NES protection strategy, we successfully designed three small fragments of CRM1, each made of four HEAT repeats and capable of binding to NESs in the absence of RanGTP. One of the fragments, C7, showed dramatically improved purification yield, thermostability, mechanostability, and resistance to protease digestion. We showed by isothermal titration that the protein kinase inhibitor NES binds to C7 at 1.18 μM affinity. Direct binding to C7 by several reported CRM1 inhibitors derived from plants were verified using pull-down assays. These fragments might be useful for the development of CRM1 inhibitors towards treatment of related diseases. The strategy applied here might help to tackle similar problems encountered in different fields.