Competitive fitness and homologous recombination of SARS-CoV-2 variants of concern.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants continue to emerge and cocirculate in humans and wild animals. The factors driving the emergence and replacement of novel variants and recombinants remain incompletely understood. Herein, we comprehensively characterized the competitive fitness of SARS-CoV-2 wild type (WT) and three variants of concern (VOCs), Alpha, Beta and Delta, by coinfection and serial passaging assays in different susceptible cells. Deep sequencing analyses revealed cell-specific competitive fitness: the Beta variant showed enhanced replication fitness during serial passage in Caco-2 cells, whereas the WT and Alpha variant showed elevated fitness in Vero E6 cells. Interestingly, a high level of neutralizing antibody sped up competition and completely reshaped the fitness advantages of different variants. More importantly, single clone purification identified a significant proportion of homologous recombinants that emerged during the passage history, and immune pressure reduced the frequency of recombination. Interestingly, a recombination hot region located between nucleotide sites 22,995 and 28,866 of the viral genomes could be identified in most of the detected recombinants. Our study not only profiled the variable competitive fitness of SARS-CoV-2 under different conditions, but also provided direct experimental evidence of homologous recombination between SARS-CoV-2 viruses, as well as a model for investigating SARS-CoV-2 recombination.

Propofol Inhibits Ferroptotic Cell Death Through the Nrf2/Gpx4 Signaling Pathway in the Mouse Model of Cerebral Ischemia-Reperfusion Injury.

Ferroptosis is characterized by excessive accumulation of iron and lipid peroxides, which are involved in ischemia, reperfusion-induced organ injury, and stroke. Propofol, an anesthetic agent, has neuroprotective effects due to its potent antioxidant, anti-ischemic, and anti-inflammatory properties. However, the relationship between propofol and ferroptosis is still unclear. In the current study, we elucidated the role of ferroptosis in the neuroprotective effect of propofol in mouse brains subjected to cerebral ischemia reperfusion injury (CIRI). Ferroptosis was confirmed by Western blotting assays, transmission electron microscopy, and glutathione assays. Propofol regulated Nrf2/Gpx4 signaling, enhanced antioxidant potential, inhibited the accumulation of lipid peroxides in CIRI-affected neurons, and significantly reversed CIRI-induced ferroptosis. Additionally, Gpx4 inhibitor RSL3 and Nrf2 inhibitor ML385 attenuated the effects of propofol on antioxidant capacity, lipid peroxidation, and ferroptosis in CIRI-affected neurons. Our data support a protective role of propofol against ferroptosis as a cause of cell death in mice with CIRI. Propofol protected against CIRI-induced ferroptosis partly by regulating the Nrf2/Gpx4 signaling pathway. These findings may contribute to the development of future therapies targeting ferroptosis induced by CIRI.

Sarsasapogenin-AA13 inhibits LPS-induced inflammatory responses in macrophage cells in vitro and relieves dimethylbenzene-induced ear edema in mice.

Sarsasapogenin-AA13 (AA13) is a novel synthetic derivative of sarsasapogenin extracted from the Chinese herb Rhizoma Anemarrhenae. In this study we investigated the effects of AA13 on lipopolysaccharide (LPS)-induced production of inflammatory factors in macrophage cells and the anti-inflammatory activity of AA13 in an inflammatory model of dimethylbenzene-induced ear edema. Macrophage cells (RAW264.7 cells and mouse peritoneal macrophages) were exposed to LPS (1 µg/mL); pretreatment with AA13 (5-20 µmol/L) dose-dependently inhibited LPS-induced production of NO, TNF-α and PGE2, and LPS-stimulated expression levels of COX-2 and iNOS. Furthermore, pretreatment with AA13 dose-dependently suppressed LPS-stimulated phosphorylation of p38 and JNK, but had no effect on ERK in RAW264.7 cells. Moreover, pretreatment with AA13 inhibited LPS-induced activation of the nuclear factor (NF)-κB in RAW264.7 cells. The in vivo anti-inflammatory activity of AA13 was demonstrated in a mouse inflammatory model: pre-treatment with either AA13 (20 mg·kg-1·d-1, ig) or a positive control antifani (10 mg·kg-1·d-1, ig) for 3 d significantly relieved dimethylbenzene-induced ear edema. Our results demonstrate that AA13 effectively inhibit LPS-induced inflammatory responses in macrophage cells in vitro and relieve dimethylbenzene-induced ear edema in vivo.

[Ligustrazine Promoted the Migration of Bone Marrow Mesenchymal Stem Cells by Up-regulating MMP-2 and MMP-9 Expressions].

OBJECTIVE: To explore the effect of ligustrazine on the migration of bone marrow mesenchymal stem cells (BMSCs) and protein expressions of matrix metalloproteinase-2 and-9 (MMP-2 and MMP-9) in vitro. METHODS: BMSCs were in vitro isolated and cultured using whole bone marrow adherent method, and phenotypes [surface positive antigens (CD29 and CD90) and negative antigens (CD34 and CD45)] identified using flow cytometry. BMSCs were divided into the blank control group, 25, 50, 100 µmol/L ligustrazine group, and the GM6001 group (100 µmol/L ligustrazine +MMPs inhibitor GM6001 ). The migration of BMSCs was tested by Transwell chamber test and wound healing assay after treated with ligustrazine for 24 h. The protein expressions of MMP-2 and MMP-9 were detected by Western blot. RESULTS: The third passage BMSCs grew well in uniform morphology. The expression rate of CD29, CD90, CD34, and CD45 was 96.9%, 97.3%, 0.2%, and 3.0%, respectively. Compared with the blank control group, the number of migrated cells and relative distance of cell invasion increased, and the protein expressions of MMP-2 and MMP-9 were elevated in each ligustrazine group (P < 0.05, P < 0.01). Compared with 100 µmol/L ligustrazine group, the number of migrated cells and relative distance of cell invasion decreased in 25 and 50 µmol/L ligustrazine groups and the GM6001 group (P < 0.01). Protein expression of MMP-2 decreased in 25 and 50 µmol/L ligustrazine groups (P < 0.01). CONCLUSION: Ligustrazine could promote the migration of BMSCs in vitro, and its mechanism might be related to up-regulating expression levels of MMP-2 and MMP-9 protein.

Knowledge mapping of research on the mitochondrial unfolded protein response: a bibliometric and visual analysis.

Background: The mitochondrial unfolded protein response (UPRmt) is a mitochondria stress response, which exerts a crucial role in maintaining mitochondrial proteostasis during stress. However, there is no bibliometric analyses systematically studied this field which could comprehensively review research trends, evaluate publication performances and provide future perspectives. Methods: Articles investigating UPRmt published between 1994 and 2021 were downloaded from the Core Collection of the Web of Science (WOS). CiteSpace and VOSviewer bibliometric software were applied for bibliometric and visual analyses. Results: A total of 2,073 papers researching UPRmt were retrieved. According to the published number of papers, the field of UPRmt research has gone through its infancy (after 2000) and rapid growth (after 2021) phases. The United States and China contributed the most to UPRmt research. Regarding the distribution of institutions, Harvard University was the most influential institution. The most prolific authors are Johan Auwerx and CM Haynes. PLoS One is the most extensive journal in the field of UPRmt research, while the Cell Death and Differentiation journal had the greatest impact among the most-authored journals. Moreover, biochemistry/molecular biology, and cell biology are the largest subject areas. UPRmt research is mainly categorized as UPRmt, transcription, endoplasmic reticulum (ER) stress, lipotoxicity, mitophagy, inflammation, skeletal muscle, hypoxia, apoptosis, mitochondrial dysfunction, neurodegeneration, mitochondrial permeability transition, and integrated stress response. Conclusions: At present, research on UPRmt is booming. Further strengthening the cooperation and exchanges between countries, institutions, and authors in the future will surely promote the development of this field.

Risk factors and machine learning prediction models for bronchopulmonary dysplasia severity in the Chinese population.

BACKGROUND: Bronchopulmonary dysplasia (BPD) is a common chronic lung disease in extremely preterm neonates. The outcome and clinical burden vary dramatically according to severity. Although some prediction tools for BPD exist, they seldom pay attention to disease severity and are based on populations in developed countries. This study aimed to develop machine learning prediction models for BPD severity based on selected clinical factors in a Chinese population. METHODS: In this retrospective, single-center study, we included patients with a gestational age < 32 weeks who were diagnosed with BPD in our neonatal intensive care unit from 2016 to 2020. We collected their clinical information during the maternal, birth and early postnatal periods. Risk factors were selected through univariable and ordinal logistic regression analyses. Prediction models based on logistic regression (LR), gradient boosting decision tree, XGBoost (XGB) and random forest (RF) models were implemented and assessed by the area under the receiver operating characteristic curve (AUC). RESULTS: We ultimately included 471 patients (279 mild, 147 moderate, and 45 severe cases). On ordinal logistic regression, gestational diabetes mellitus, initial fraction of inspiration O2 value, invasive ventilation, acidosis, hypochloremia, C-reactive protein level, patent ductus arteriosus and Gram-negative respiratory culture were independent risk factors for BPD severity. All the XGB, LR and RF models (AUC = 0.85, 0.86 and 0.84, respectively) all had good performance. CONCLUSIONS: We found risk factors for BPD severity in our population and developed machine learning models based on them. The models have good performance and can be used to aid in predicting BPD severity in the Chinese population.

Anti-tumor activity and linear-diarylheptanoids of herbal couple Curcumae Rhizoma-Sparganii Rhizoma and the single herbs.

ETHNOPHARMACOLOGICAL RELEVANCE: Curcumae Rhizoma and Sparganii Rhizoma (CR-SR) are the classical herbal couple for activating blood circulation and treating tumor in clinics. AIM OF THE STUDY: To investigate the anti-tumor activity and to clarify the bioactive ingredients of herbal couple CR-SR and the single herbs Curcumae Rhizoma (CR) and Sparganii Rhizoma (SR). MATERIALS AND METHODS: The active fractions of CR-SR decoction were fractioned by column chromatography. And isolated compounds were characterized by IR, ESI-MS, 1D and 2D-NMR techniques. Detecting linear-diarylheptanoids in CR-SR, CR and SR was realized through UPLC-LTQ-Orbitrap MSn, based on the fragmentation pathways established in this study, comparison with MS data of isolated compounds and references. The anti-tumor activities of different solvent fractions from CR-SR, CR and SR, as well as isolated ingredients were tested by CCK-8 method. RESULTS: Ultimately, a new compound (1), having a sulfonic acid group at C-3, named demethoxyshogasulfonic acid, along with another structurally similar 17 known linear-diarylheptanoids were isolated. These linear-diarylheptanoids (1-18) were divided into 12 categories based on the differences of substituents at C-3 and C-5 on the straight chain of seven carbons. Six fragmentation pathways were established by summarizing MS data of the 18 isolated compounds collected from UPLC-MS. Based on that, and retention times and MS fragmentation ions, 47 linear-diarylheptanoids were identified in CR-SR and CR, in which 12 linear-diarylheptanoids were also detected in SR. Most importantly, 5 sulfonated linear-diarylheptanoids were new compounds detected in CR and CR-SR. And the biological assay indicated that compounds 1-4 and 12-15 significantly reduced the proliferation and inhibited colony formation of MCF-7 and HepG2 cells. CONCLUSION: The new compound (1) exhibited good anti-cancer activity, which suggests that a great effort has to be paid to investigate the bioactivity of sulfonated compounds. The fractions of CR-SR decoction exhibited stronger anti-tumor activities than that of CR and SR against 5 different cancer cells. As for chemical composition, it is the first time to report that diarylheptanoids are in Sparganiaceae and the sulfonated compounds in Zingiberaceae. Moreover, the linear-diarylheptanoids found in SR which being tested to possess good anti-tumor activity, plus those compounds in CR enhance the capacity of CR-SR. It shows importance of TCM compatibility.