A New Method for Programmable RNA Editing Using CRISPR Effector Cas13X.1.

Type VI CRISPR-Cas13 is the only CRISPR system that can bind and cleave RNA without DNase activity. We used the newly discovered, smaller Cas13X.1 protein to construct an editing system in mammalian cells, aiming to break the delivery restrictions of CRISPR-Cas13 system in vivo and promote the application of Cas13X system in clinical therapy. We employed exogenous fluorescence reporter gene mCherry and endogenous gene transketolase (TKT) closely related to cancer cell metabolism as target genes to evaluate the Cas13X.1 system. The recombinant plasmids targeting exogenous gene mCherry and endogenous gene TKT were constructed based on Cas13X.1 backbone plasmid. The editing efficiency, protein expression level, downstream gene transcript level and safety of Cas13X.1 system were evaluated. Both TKT transcripts of endogenous genes and mCherry transcripts of exogenous genes were significantly degraded by Cas13X.1 system with a knockdown efficiency up to 50%. At the same time, Cas13X.1 down-regulated the expression of the corresponding protein level in the editing of transcripts. In addition, the transcripts of key metabolic enzymes related to TKT were also down-regulated synchronously, suggesting that the degradation of TKT transcripts by Cas13X.1 system affected the main metabolic pathways related to TKT. The morphology, RNA integrity and apoptosis of cells loaded with Cas13X.1 system were not affected. The Cas13X.1 system we constructed had strong RNA knockdown ability in mammalian cells with low cellular toxicity. Compared with other CRISPR-Cas13 systems, Cas13X.1 system with smaller molecular weight has more advantages in vivo delivery. The Cas13X.1 system targeting TKT transcripts also provides an alternative method for the study of anti-cancer therapy.

Bone Marrow Mesenchymal Stem Cell-Derived Exosomes Alleviate Peritoneal Dialysis-Associated Peritoneal Injury.

Peritoneal fibrosis is a critical sequela that limits the application of peritoneal dialysis (PD). This study explored the role and mechanism of bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos) in preventing PD-associated peritoneal injury. C57BL/6 mice were randomized into three groups: a control (saline), peritoneal injury [2.5% glucose peritoneal dialysate + lipopolysaccharide (LPS)], and peritoneal injury + exosome group. After 6 weeks, mice were dissected, and the parietal peritoneum was collected. The level of peritoneal structural and functional damage was assessed. Additionally, transcriptome analysis of the peritoneum and miRNA sequencing on BMSC-Exos were performed. The parietal peritoneum had significantly thickened, and peritoneal function was impaired in the peritoneal injury group. Peritoneal structural and functional damage was significantly reduced after exosome treatment, while peritoneal inflammation, fibrosis, angiogenesis, and mesothelial damage significantly increased. Transcriptomic analysis showed that the BMSC-Exos affected the cell cycle process, cell differentiation, and inflammatory response regulation. Significant pathways in the exosome group were enriched by inflammation, immune response, and cell differentiation, which constitute a molecular network that regulates the peritoneal protective mechanism. Additionally, inflammatory factors (TNF-α, IL-1ß), fibrosis markers (α-SMA, collagen-III, fibronectin), profibrotic cytokines (TGF-ß1), and angiogenesis-related factor (VEGF) were downregulated at the mRNA and protein levels through BMSC-Exos treatment. BMSC-Exos treatment can prevent peritoneal injury by inhibiting peritoneal fibrosis, inflammation, and angiogenesis, showing a multitarget regulatory effect. Therefore, BMSC-Exos therapy might be a new therapeutic strategy for treating peritoneal injury.

Sepsis-induced immunosuppression: mechanisms, diagnosis and current treatment options.

Sepsis is a common complication of combat injuries and trauma, and is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. It is also one of the significant causes of death and increased health care costs in modern intensive care units. The use of antibiotics, fluid resuscitation, and organ support therapy have limited prognostic impact in patients with sepsis. Although its pathophysiology remains elusive, immunosuppression is now recognized as one of the major causes of septic death. Sepsis-induced immunosuppression is resulted from disruption of immune homeostasis. It is characterized by the release of anti-inflammatory cytokines, abnormal death of immune effector cells, hyperproliferation of immune suppressor cells, and expression of immune checkpoints. By targeting immunosuppression, especially with immune checkpoint inhibitors, preclinical studies have demonstrated the reversal of immunocyte dysfunctions and established host resistance. Here, we comprehensively discuss recent findings on the mechanisms, regulation and biomarkers of sepsis-induced immunosuppression and highlight their implications for developing effective strategies to treat patients with septic shock.

A Study on the Design of Vision Protection Products Based on Children's Visual Fatigue under Online Learning Scenarios.

The rate of myopia in children is increasing rapidly under online learning scenarios. One of the important reasons for this is incorrect reading and writing posture. Three screen view parameters (viewing angle, viewing height, and viewing distance) are selected as significant influencing factors and blink rating is used as a sign of visual fatigue through literature analysis to study the influence factors of myopia in children, and their correlation. Children's visual fatigue is evaluated by subjective evaluation and is recording using an eye tracker for changes in the three factors through online learning scenario simulation experiment. An optimal regression model is constructed that illustrates the relationship between the three variables and the visual fatigue levels. The aim of this study is to confirm the quantitative relationship between the screen view parameters and visual fatigue, and to design a child vision protection product on this basis. The test results show there is a linear positive correlation between the viewing angle, viewing height, and viewing distance. A vision protection device has been designed based on this model and was verified through function prototype testing. The result of this study quantified the relationship among screen view parameters and children's visual fatigue, which provides a theoretical basis for the design of a children's visual protection device.

Establishment of a novel mouse peritoneal dialysis-associated peritoneal injury model.

BACKGROUND: Peritoneal fibrosis induced by various factors during peritoneal dialysis (PD) can eventually lead to ultrafiltration failure and termination of PD treatment. The existing animal models are caused by a single stimulus, and cannot accurately simulate complex pathogenesis of peritoneal injury and fibrosis. We aim to develop an efficient and realistic mouse model of PD-associated peritoneal injury using daily intraperitoneal injection (I.P.) of human peritonitis PD effluent. METHODS: Eight-week-old male C57BL/6 mice were classified into six groups: saline control; 2.5% PD fluid; 2.5% PD fluid + lipopolysaccharide (LPS); 4.25% PD fluid; 4.25% PD fluid + LPS; and peritonitis effluent. Mice received daily I.P. for 6 weeks, and were sacrificed to determine peritoneal structural and functional damage, inflammation, and fibrosis. RESULTS: Mice in the peritonitis effluent group had low mortality. The submesothelial thickness in the peritonitis effluent group was significantly greater than that in the 2.5% PD fluid group. The peritonitis effluent group had increased expression of fibrosis markers (α-SMA, Collagen I, etc.), neutrophil granulocytes (MPO), and macrophages (CD68, F4/80) in the peritoneum based on immunohistochemical staining; and significantly higher expression of inflammation markers (IL-1ß, IL-6, etc.) and fibrosis markers (TGF-ß1, α-SMA, etc.) based on real-time qPCR. Modified peritoneal equilibration tests (PET) demonstrated that I.P. of peritonitis effluent reduced peritoneal ultrafiltration. CONCLUSION: Our novel animal model of PD-associated peritoneal injury faithfully simulates the clinical pathophysiological process. This animal model may be useful for study of the pathogenesis of PD-associated peritoneal injury and identification of novel treatments.

Viral sepsis is a complication in patients with Novel Corona Virus Disease (COVID-19).

BACKGROUND: Until June 23th 2020, 9,195,635 laboratory-confirmed cases of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection have been reported worldwide, including 473,127 deaths. Bacterial infection is the main cause of sepsis, however, sepsis caused by virus is often ignored. Increased awareness, early recognition of viral sepsis, rapid administration of appropriate antiviral drugs, and urgent treatment can significantly reduce deaths of viral sepsis. OBJECTIVES: Given the rapid global spread of novel Corona Virus Disease (COVID-19), coupled with the high rate of missed diagnosis of viral sepsis caused by SARS-CoV-2 infection, it is urgent to evaluate the multiple organ failure score and viral sepsis in COVID-19 patients, so as to determine the clinical characteristics of viral sepsis more accurately and reveal the risk factors related to mortality. METHODS: Here we provide a full description of three cases of viral sepsis and subsequent multiple organ dysfunction (MODS) caused by SARS-CoV-2 infection imported to Guiyang from Wuhan. RESULTS: We analyzed complete laboratory examination, imaging data and treatment methods for the patients and assessed Sepsis-related Organ Failure Assessment score (SOFA score) and Multiple organ dysfunction scores (MOD score) daily, aimed to elucidate the clinical feature of viral sepsis and MODS and to attract enough attention by clinicians. CONCLUSIONS: Therefore, we strongly suggest to daily evaluate SOFA score and MOD score in severe and critically-ill COVID-19 patients, so as to early diagnose and prevention of sepsis and MODS.Given the rapid global spread of novel Corona Virus Disease (COVID-19), coupled with the high rate of missed diagnosis of viral sepsis caused by SARS-CoV-2 infection, it is urgent to evaluate the multiple organ failure score and viral sepsis in COVID-19 patients, so as to determine the clinical characteristics of viral sepsis more accurately and reveal the risk factors related to mortality. Here we provide a full description of three cases of viral sepsis and subsequent multiple organ dysfunction (MODS) caused by SARS-CoV-2 infection imported to Guiyang from Wuhan. We analyzed complete laboratory examination, imaging data and treatment methods for the patients and assessed Sepsis-related Organ Failure Assessment score (SOFA score) and Multiple organ dysfunction scores (MOD score) daily, aimed to elucidate the clinical feature of viral sepsis and MODS and to attract enough attention by clinicians. Therefore, we strongly suggest to daily evaluate SOFA score and MOD score in severe and critically-ill COVID-19 patients, so as to early diagnose and prevention of sepsis and MODS.