Labeling Endogenous Proteins Using CRISPR-mediated Insertion of Exon (CRISPIE)

The CRISPR/Cas9 technology has transformed our ability to edit eukaryotic genomes. Despite this breakthrough, it remains challenging to precisely knock-in large DNA sequences, such as those encoding a fluorescent protein, for labeling or modifying a target protein in post-mitotic cells. Previous efforts focusing on sequence insertion to the protein coding sequence often suffer from insertions/deletions (INDELs) resulting from the efficient non-homologous end joining pathway (NHEJ). To overcome this limitation, we have developed CRISPR-mediated insertion of exon (CRISPIE). CRISPIE circumvents INDELs and other editing errors by inserting a designer exon flanked by adjacent intron sequences into an appropriate intronic location of the targeted gene. Because INDELs at the insertion junction can be spliced out, "CRISPIEd" genes produce precisely edited mRNA transcripts that are virtually error-free. In part due to the elimination of INDELs, high-efficiency labeling can be achieved in vivo. CRISPIE is compatible with both N- and C-terminal labels, and with all common transfection methods. Importantly, CRISPIE allows for later removal of the protein modification by including exogenous single-guide RNA (sgRNA) sites in the intronic region of the donor module. This protocol provides the detailed CRISPIE methodology, using endogenous labeling of β-actin in human U-2 OS cells with enhanced green fluorescent protein (EGFP) as an example. When combined with the appropriate gene delivery methods, the same methodology can be applied to label post-mitotic neurons in culture and in vivo. This methodology can also be readily adapted for use in other gene editing contexts.

PERK signaling activation restores nucleus pulposus degeneration by activating autophagy under hypoxia environment

OBJECTIVES

Intervertebral disc (IVD) degeneration is an important disease with no efficient biological therapy identified. Autophagy, a wildly known therapeutic target for human disease, has been demonstrated to be activated under hypoxia, with underlying mechanism remains elusive. Thus, this study aims to specify the role of autophagy in IVD degeneration, the regulating mechanism of hypoxia-inducing autophagy, and the therapeutic value of autophagy for IVD degeneration.

METHODS

RNA-seq was used to screen the primary pathway affected in NP cells under hypoxia, the specific link between hypoxia and autophagy were investigated using ChIP-seq and dual luciferase reporter assay. Conditional ATG7 knockout mice (ATG7^-/-) were constructed for assessing the effect of autophagy on IVD degeneration, and puncture induced mice model of IVD degeneration were used for intradiscal injection to evaluate the therapeutic value of autophagy.

RESULTS

We demonstrated that hypoxia induces autophagy by transcriptional activation of autophagic gene LC3B and ATG7, which is controlled by PERK signaling. Then, we observed that inhibiting autophagy or PERK signaling leads to impaired NP cell viability and function, furthermore, using ATG7 knockout (ATG7^-/-) mice, we identified the protective role of autophagy in IVD. Furthermore, we found that intradiscal injection of PERK signaling agonist, CCT020312, significantly restores the degeneration level of needle punctured mice IVD.

CONCLUSION

We showed that the activation of PERK signaling upon hypoxia serves as a vital mechanism to induce autophagy and identified the therapeutic value of PERK signaling agonist for IVD degeneration treatment.

Safety and efficacy of dendritic cell-based immunotherapy (DCVAC/LuCa) combined with carboplatin/pemetrexed for patients with advanced non-squamous non-small-cell lung cancer without oncogenic drivers

Background

Our prospective, open-label, single-arm phase II study investigated the safety and efficacy of DCVAC/LuCa (dendritic cell vaccines for lung cancer) combined with standard carboplatin/pemetrexed in advanced non-squamous (nsq) non-small-cell lung cancer (NSCLC).

Patients and methods

Eligible patients had stage IV nsq NSCLC without oncogenic drivers and had not received prior systemic cancer therapy. Treatment consisted of carboplatin/pemetrexed for up to 6 cycles followed by 21 cycles of pemetrexed maintenance or until progression or intolerance. Non-progression patients after two cycles of chemotherapy started to receive DCVAC/LuCa subcutaneously (s.c.) on day 15 of cycle 3, and thereafter q3w (day 15 of chemotherapy cycles) for up to 15 doses. Dosing of DCVAC/LuCa s.c. varied among patients depending on the baseline number of leucocytes but remained constant for each single patient. Safety was assessed by adverse events (AEs), treatment-related adverse events (TRAEs), serious adverse events (SAEs), and adverse events of special interest (AESIs). Efficacy was measured by overall survival (OS), progression-free survival (PFS), time to progression (TTP), and objective response rate (ORR).

Results

Sixty-one patients were enrolled. In the safety population (n = 60), eight patients (13.33%) had grade 3 or greater TRAEs, and six patients (10.0%) showed SAEs which were not related to leukapheresis or DC vaccination. Six grade 1 AEs were considered to be related to leukapheresis. No AESIs or DCVAC/LuCa-induced AEs were observed. The 2-year survival rate in the modified intention-to-treat population (n = 44) was 52.57%. Median OS was not reached. Median PFS was 8.0 months, median TTP was 10.2 months, and the ORR was 31.82%.

Conclusion

In treatment-naïve stage IV nsq NSCLC patients without oncogenic drivers, the combination of carboplatin/pemetrexed and DCVAC/LuCa was well tolerated and showed promising efficacy. Therefore, a study to prove our immunotherapeutic concept in a randomized phase III trial is planned.

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We investigated the safety and efficacy of DCVAC/LuCa combined with standard carboplatin/pemetrexed in nsq NSCLC.

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The combination therapy showed a favorable tolerability profile in a selected Chinese population.

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The 2-year survival rate in the modified intention-to-treat population (n = 44) was 52.57%.

Distinct in vivo dynamics of excitatory synapses onto cortical pyramidal neurons and parvalbumin-positive interneurons

Cortical function relies on the balanced activation of excitatory and inhibitory neurons. However, little is known about the organization and dynamics of shaft excitatory synapses onto cortical inhibitory interneurons. Here, we use the excitatory postsynaptic marker PSD-95, fluorescently labeled at endogenous levels, as a proxy for excitatory synapses onto layer 2/3 pyramidal neurons and parvalbumin-positive (PV⁺) interneurons in the barrel cortex of adult mice. Longitudinal in vivo imaging under baseline conditions reveals that, although synaptic weights in both neuronal types are log-normally distributed, synapses onto PV⁺ neurons are less heterogeneous and more stable. Markov model analyses suggest that the synaptic weight distribution is set intrinsically by ongoing cell-type-specific dynamics, and substantial changes are due to accumulated gradual changes. Synaptic weight dynamics are multiplicative, i.e., changes scale with weights, although PV⁺ synapses also exhibit an additive component. These results reveal that cell-type-specific processes govern cortical synaptic strengths and dynamics.

Melander et al. use a genetic strategy to visualize excitatory neuronal connections that cannot be inferred from morphology, and they monitor how the connections change over weeks in mice. They find distinct characteristics between synapses onto cells that “suppress” brain activity and those onto cells that “excite” brain activity.

Genetically encoded sensors towards imaging cAMP and PKA activity in vivo

Cyclic adenosine monophosphate (cAMP) is a universal second messenger that plays a crucial role in diverse biological functions, ranging from transcription to neuronal plasticity, and from development to learning and memory. In the nervous system, cAMP integrates inputs from many neuromodulators across a wide range of timescales - from seconds to hours - to modulate neuronal excitability and plasticity in brain circuits during different animal behavioral states. cAMP signaling events are both cell-specific and subcellularly compartmentalized. The same stimulus may result in different, sometimes opposite, cAMP dynamics in different cells or subcellular compartments. Additionally, the activity of protein kinase A (PKA), a major cAMP effector, is also spatiotemporally regulated. For these reasons, many laboratories have made great strides toward visualizing the intracellular dynamics of cAMP and PKA. To date, more than 80 genetically encoded sensors, including original and improved variants, have been published. It is starting to become possible to visualize cAMP and PKA signaling events in vivo, which is required to study behaviorally relevant cAMP/PKA signaling mechanisms. Despite significant progress, further developments are needed to enhance the signal-to-noise ratio and practical utility of these sensors. This review summarizes the recent advances and challenges in genetically encoded cAMP and PKA sensors with an emphasis on in vivo imaging in the brain during behavior.

[Surface modification of titanium implant with hBMP-2/hIGF-1 for promoting biocompatibility and osteogenesis]

OBJECTIVE

To prepare the human bone morphogenetic protein-2(hBMP-2)/human insulin-like growth factor-1(hIGF-1)coating titanium(Ti)and assess its performance as a dental implant material.

METHODS

hBMP-2 and hIGF-1 were coated to the smooth surface of a Ti plate, and its efficacy for promoting bone formation and bone integration was compared with a pristine Ti plate.The surface characteristics of the metal samples were evaluated using scanning electron microscope (SEM) and by contact angle measurement.MG63 cells were seeded on the surface of the Ti plates, and MTT assay and alizarin red staining was used to examine the cell proliferation and formation of calcified nodules, respectively.Alkaline phosphatase (ALP)secretion of the cells was examined with ELISA, and cellular expressions of osteocalcin and osteopontin were detected with Western blotting for assessing osteogenesis.

RESULTS

SEM examination showed that the surface of Ti with hBMP-2 and hIGF-1 coating presented with a radial pattern resembling snowflakes.The contact angles of non-coated Ti, hBMP-2-coated Ti, hIGF-1-coated, and hBMP-2/-hIGF-1-coated Ti samples were 83.2°, 54°, 56° and 54°, respectively.Compared with the non-coated Ti plate, the surface-modified Ti samples showed a significantly smaller contact angle (P=0.032, 0.029, and 0.028), indicating a good hydrophilicity of the samples.MTT assay showed that MG63 cells grew well on the surface of the coated Ti plates.The hBMP-2/IGF-1 coating significantly induced cellular secretion of ALP(P=0.021, 0.014)and obviously promoted osteogenesis of MG63 cells (P < 0.05).Western blotting results showed that hBMP-2/IGF-1 coating significantly enhanced the expressions of osteocalcin and osteopontin in the seeded cells (P < 0.05).

CONCLUSION

hBMP-2 and hIGF-1 coating of Ti material can promote osteogenesis of the cells seeded on its surface to improve the performance of such Ti material as dental implants.

High-fidelity, efficient, and reversible labeling of endogenous proteins using CRISPR-based designer exon insertion

Precise and efficient insertion of large DNA fragments into somatic cells using gene editing technologies to label or modify endogenous proteins remains challenging. Non-specific insertions/deletions (INDELs) resulting from the non-homologous end joining pathway make the process error-prone. Further, the insert is not readily removable. Here, we describe a method called CRISPR-mediated insertion of exon (CRISPIE) that can precisely and reversibly label endogenous proteins using CRISPR/Cas9-based editing. CRISPIE inserts a designer donor module, which consists of an exon encoding the protein sequence flanked by intron sequences, into an intronic location in the target gene. INDELs at the insertion junction will be spliced out, leaving mRNAs nearly error-free. We used CRISPIE to fluorescently label endogenous proteins in mammalian neurons in vivo with previously unachieved efficiency. We demonstrate that this method is broadly applicable, and that the insert can be readily removed later. CRISPIE permits protein sequence insertion with high fidelity, efficiency, and flexibility.

AB0564 RHEUMATOLOGISTS’ VIEWS AND EXPERIENCES IN MANAGING PsA PATIENTS BASED ON TREATING TO TARGET STRATEGY: A CROSS-SECTIONAL STUDY IN CHINA

Background:

Psoriatic arthritis (PsA) is a chronic inflammatory arthritis with progressive, erosive destruction associated with functional impairment. Principles of treat-to-target (T2T) have been widely used in rheumatoid arthritis, which has powerfully improved patient outcomes. In 2017, the concept of T2T has proposed to apply in PsA patients. However, the awareness and implementation of evidence-based T2T treatment guidelines varies across different geographical regions of China, hospital grades, professional status and specialities.

Objectives:

The study aimed to investigate Rheumatologists’ views and experiences in managing PsA patients with T2T strategy in china.

Methods:

A cross-sectional questionnaire survey of Rheumatologists in China from 5 August to 15 August 2020 was conducted for this study. Rheumatologists were contacted by WeChat (a Chinese cell/web app) and asked to complete a web-based questionnaire anonymously. The electronic questionnaire was sent out by the internet platform of WenJuanXing via WeChat (https://www.wjx.cn/). The questionnaire was designed to collect: (a) demographic information; (b) patient management in clinical practice for Rheumatologists; (c) familiarity and application of T2T strategy in Rheumatologists. P values ≤0.05 were considered significant.

Results:

(1) A total of 823 rheumatologists (69.87% female, 30.13% male) provided valid answers to the questionnaire. 71.09% of the participants major in Modern Western Medicine, 28.91% major in traditional chinese medicine. A total of 75.94% worked in Grade-A Tertiary Hospital. A total of 52.73% had more than 10 years of work experience and 63.55% had High-level title. (2) More than half of the patients were followed up by 69% Rheumatologists in their daily practice. The proportion of follow-up patients increased powerfully in the group of Rheumatologists who major in Modern Western Medicine (P=0.014), work in Grade-A Tertiary Hospital (P<0.001), have more than 10 years of work experience (P<0.001) and High-level title (P<0.001). (3) 36.45% Rheumatologist thought the frequency for patient disease activity assessment was every 1 month and 53.1% was every 3 months. And 41.7% Rheumatologist prefer to use PASDAS for disease activity criteria, and only 3.6% choose MDA. (4) A total of 62.43% thought they were familiar with T2T strategy, and 83.6% Rheumatologists applied T2T strategy in clinical practice. Among 135 Rheumatologists who did not apply T2T strategy, 62.2% of Rheumatologists thought that the main barrier to T2T application was that they did not fully understand the strategy. The frequency of application of T2T strategy in clinical practice was significantly different between Rheumatologists who major in Modern Western Medicine (60.75%) and traditional chinese medicine (22.84%) (P=0.023).

Conclusion:

In china, the management of PsA patients need to be standardized to improve patient outcomes. And the promotion of T2T strategy in PsA need to be further strengthened.

References:

[1]Smolen JS, Schöls M, Braun J,et al. Treating axial spondyloarthritis and peripheral spondyloarthritis, especially psoriatic arthritis, to target: 2017 update of recommendations by an international task force. Ann Rheum Dis. 2018 Jan;77(1):3-17.

[2]Tucker LJ, Ye W, Coates LC. Novel Concepts in Psoriatic Arthritis Management: Can We Treat to Target? Curr Rheumatol Rep. 2018 Sep 18;20(11):71.

[3]Coates LC, Helliwell PS. Treating to target in psoriatic arthritis: how to implement in clinical practice. Ann Rheum Dis. 2016;75(4):640-643.

Figure 1

A. Rheumatologist priority of frequency for patient follow-up in different disease status. B. Rheumatologist priority of frequency for patient disease activity assessment in clinical practice. C. Rheumatologist priority of disease activity criteria for PsA patients.

Disclosure of Interests:

None declared.

AB0372 TOCILIZUMAB WAS EFFECTIVE IN REFRACTORY ARTERIAL INVOLVEMENT OF BEHCET’S DISEASE: A REAL-LIFE SINGLE- CENTER EXPERIENCE IN CHINA

Background:

Behcet’s disease (BD) is a chronic and relapsing vasculitis, in which major vessel involvement is a main cause of mortality and morbidity. The therapeutic arsenal is mainly composed of classical immunosuppressants. However, when faced with resistance to these drugs, no alternative therapeutic strategy is currently recommended.

Objectives:

To assess the efficacy and safety of interleukin 6 receptor inhibitor tocilizumab (TCZ) in refractory arterial involvement of BD in a real-life observational setting.

Methods:

10 patients were enrolled in our center between 2014 and 2019. All patients met the international criteria for BD and had severe arterial involvement evaluated by echocardiography, angio-Computerized Tomography scan and vascular Doppler. The diagnosis of refractory arterio-BD was based on objective vascular symptoms not explained by any other known disease and non-response to conventional immunosuppressants combined with glucocorticoids therapy. All patients underwent TCZ infusions at 8mg/kg every 4 weeks. Concomitant therapy with immunosuppressants and glucocorticoids was continued. Clinical and imaging findings were assessed before and after TCZ therapy. All adverse events were recorded during follow-up.

Results:

All the patients were males, with a mean age of 44.3±10.5 years in this study. The mean age at presentation of arterial involvement was 40.8±9.2 years old. The patterns of arterial involvement were aneurysm (n=9), stenosis (n=3) and aortic valve lesion (n=2). After a mean follow-up of 26.8±7.2 months, TCZ yielded rapid and maintained clinical improvement in 9 patients, with complete remission in 6 of them and partial response in 3 of them. Discontinuation of TCZ treatment due to relapse occurred in one case as the enlargement of abdominal aortic aneurysm. The mean glucocorticoid dosage was tapered from 54.5±20.6mg/d to 8.3±3.6mg/d (p<0.001). And the use of immunosuppressants was tapered in 4 (40.0%) patients. As for serological improvement, the median ESR and CRP levels decreased from 50 (2-82) mm/h and 32.9 (2.1-62.3) mg/dL to 4 (1-10) mm/h (p<0.001) and 2.9 (0.2-12.1) mg/dL (p<0.001), respectively. Radiologic improvement of artery lesion was demonstrated in 4(40%) patients. None of the patients had serious adverse events during follow-up.

Conclusion:

TCZ was a safe and effective therapeutic option for refractory arterial involvement of BD, with a favorable steroid-sparing effect.

References:

[1]G Hatemi, R Christensen, D Bang, et al. 2018 update of the EULAR recommendations for the management of Behçet’s syndrome. Ann Rheum Dis. 2018;77(6):808-818.

[2]Y Ozguler, P Leccese, R Christensen, et al. Management of major organ involvement of Behcet’s syndrome: a systematic review for update of the EULAR recommendations. Rheumatology (Oxford). 2018;57(12):2200-2212.

[3]M Akiyama, Y Kaneko, T Takeuchi. Effectiveness of tocilizumab in Behcet’s disease: A systematic literature review. Semin Arthritis Rheum. 2020;50(4):797-804.

Table 1.

Tocilizumab therapy in ten cases of refractory arterio-BD

PatientAge, yearDisease duration, monthsClinical features*Arterial lesionsPrevious therapyResponse at week 24134228O, G, P, S, IStenosis of CA/ SMA/RA/SCA, aortic valve prolapsePred/CYC/MMFCR22024O, SDissecting aneurysm of AA (Debakey I)Pred/MMFPR367276O, G, P, S, Athoracoabdominal aortic aneurysmPred/CYC/TACCR46775O, S, UStenosis of LAD/LCX/RCAPred /CYCCR55080O, G, AAbdominal and coronary aortic aneurysmsPred /CYCRelapse64826O, GAortic insufficiencyPred /CYCPR726147O, P, S, VIliac artery aneurysmPred /MMFCR849466O, S, VThoracoabdominal and coronary aortic aneurysmsPred /CYC/AZACR927181O, P, SPseudoaneurysm of CCAPred /CYCPR10Male/55354O, P, SAbdominal aneurysm, stenosis of LAD/LCX/RCAPred /CYC/AZACR

*O: oral ulcer; G: genital ulcer; P: pathergy test; S: skin lesions; I: intestinal ulcer; A: arthritis; U: uveitis; V: venous thrombosis

Figure 1.

Changes from baseline in BSAS, BDCAF, ESR, CRP and steroid daily dose at 24 weeks

Disclosure of Interests:

None declared

Deposition of resistant bacteria and resistome through FMT in germ-free piglets

Faecal microbiota transplantation (FMT) has received considerable attention in recent years due to its remarkable efficacy in restoring a normal gut microbiome. Here, we established the groups of post-FMT recipient piglets using germ-free piglets during early life to characterize the colonization of gut microbiota composition and the enrichment of resistance gene acquisition. By metagenomic analysis, we identified 115 bacterial phyla and 2111 bacterial genera that were acquired by the FMT recipients. We found that early-life microbial colonization and the spread of resistomes in recipient piglets were age dependent. A total of 425, 425 and 358 AR genes primarily belonging to 114, 114 and 102 different types were detected in the donors, post-FMT recipients in the FMT-3D group and post-FMT recipients in the FMT-15D group respectively. Genes that encoded tetracycline, macrolide and chloramphenicol resistance proteins were the most dominant AR genes, and the results corresponded with the exposure of antibiotic consumption at farm. Bacteroides, Escherichia, Clostridium, Parabacteroides, Treponema, Lactobacillus and Enterococcus were significantly correlated with the distribution of AR genes. More importantly, the relative abundance of AR genes was positively correlated with the levels of mobile genetic elements. Our results indicate that early-life microbial colonization can persistently shape the gut microbiota and antibiotic resistome.

[Epidemiology and the risk factors of myopia among children and youths in Yunnan province]

Objective: The purpose of the study was to describe the prevalence of myopia and to explore the associated factors of myopia among Han and Yi students aged 5-16 years in Yunnan province, China. Methods: A total of 5 971 Han and Yi students were included in the data analysis from the Yunnan eye study which was conducted from March to August, 2014. Information regarding demographic factors, socioeconomic status and lifestyle-related exposures were collected by per-designed questionnaires. The ophthalmic examinations including distance visual acuity, anterior segment examination, cycloplegic auto-refraction, and ocular motility examination were conducted. Logistic regression models were fitted to estimate the risk factors for myopia. Results: The age of 5 971 subjects was (10.68±2.24)years old, and the total prevalence of myopia and high myopia was 48.05% and 0.59%. Myopia prevalence was found to be higher in Han students compared with Yi ethnicity (50.20% vs. 47.10%,P=0.029). In multivariate analysis, the occurrence of myopia was associated with age (OR=1.28, 95%CI: 1.25-1.31), girls (OR=1.32, 95%CI: 1.18-1.48), increasing reading and writing time per day (OR=1.13, 95%CI: 1.07-1.20), having self-reported myopia among friend(s) (OR=1.15, 95%CI: 1.02-1.29), having myopic father (OR=1.38, 95%CI: 1.06-1.79), having myopic mother (OR=1.43, 95%CI: 1.12-1.83) and higher educated mother (OR=1.24, 95%CI: 1.03-1.51). Conclusions: We observed a high prevalence of myopia among Mangshi students. The presence of myopia was associated with increasing age, girls, increasing reading and writing time per day, having self-reported myopia among friend(s), having myopic father, having myopic and high educated mother.