Enhancing the stability and therapeutic potential of the antimicrobial peptide Feleucin-K3 against Multidrug-Resistant a. Baumannii through rational utilization of a D-amino acid substitution strategy.

Antimicrobial peptides (AMPs), which have a low probability of developing resistance, are considered the most promising antimicrobial agents for combating antibiotic resistance. Feleucin-K3 is an amphiphilic cationic AMP that exhibits broad-spectrum antimicrobial activity. In our previous research, the first phenylalanine residue was identified as the critical position affecting its biological activity. Here, a series of Feleucin-K3 analogs containing hydrophobic D-amino acids were developed, leveraging the low sensitivity of proteases to unnatural amino acids and the regulatory effect of hydrophobicity on antimicrobial activity. Among them, K-1dF, which replaced the phenylalanine of Feleucin-K3 with its enantiomer (D-phenylalanine), exhibited potent antimicrobial activity with a therapeutic index of 46.97 and MICs between 4 to 8 µg/ml against both sensitive and multidrug-resistant Acinetobacter baumannii. The introduction of D-phenylalanine increased the salt tolerance and serum stability of Feleucin-K3. Moreover, K-1dF displayed a rapid bactericidal effect, a low propensity to develop resistance, and a synergistic effect when combined with antibiotics. More importantly, it exhibited considerable or superior efficacy to imipenem against pneumonia and skin abscess infection. In brief, the K-1dF obtained by simple and effective modification strategy has emerged as a promising candidate antimicrobial agent for tackling multidrug-resistant Acinetobacter baumannii infections.

Improvement of biotic nitrate reduction in constructed photoautotrophic biofilm-soil microbial fuel cells.

The biotic nitrate reduction rate in freshwater ecosystems is typically constrained by the scarcity of carbon sources. In this study, 'two-chambers' - 'two-electrodes' photoautotrophic biofilm-soil microbial fuel cells (P-SMFC) was developed to accelerate nitrate reduction by activating in situ electron donors that originated from the soil organic carbon (SOC). The nitrate reduction rate of P-SMFC (0.1341 d-1) improved by âˆ¼ 1.6 times on the 28th day compared to the control photoautotrophic biofilm. The relative abundance of electroactive bacterium increased in the P-SMFC and this bacterium contributed to obtain electrons from SOC. Biochar amendment decreased the resistivity of P-SMFC, increased the electron transferring efficiency, and mitigated anodic acidification, which continuously facilitated the thriving of putative electroactive bacterium and promoted current generation. The results from physiological and ecological tests revealed that the cathodic photoautotrophic biofilm produced more extracellular protein, increased the relative abundance of Lachnospiraceae, Magnetospirillaceae, Pseudomonadaceae, and Sphingomonadaceae, and improved the activity of nitrate reductase and ATPase. Correspondingly, P-SMFC in the presence of biochar achieved the highest reaction rate constant for nitrate reduction (kobs) (0.2092 d-1) which was 2.4 times higher than the control photoautotrophic biofilm. This study provided a new strategy to vitalize in situ carbon sources in paddy soil for nitrate reduction by the construction of P-SMFC.

The proteomic analysis uncovers the cellular responses to the African swine fever virus membrane proteins p54, p17, and pB117L.

African swine fever virus (ASFV) infection causes African swine fever (ASF), a highly contagious and fatal disease that poses severe threat to swine production. To gain insights into the host responses to ASFV, we generated recombinant adenovirus Ad5 expressing viral membrane proteins p54, p17, and pB117L individually and infected an alveolar cell line, 3D4/21, with these recombinant viruses. Then, the cell lysates were analyzed using label-free quantification proteomic analysis method. A total of 2158 differentially expressed proteins (DEPs) were identified, of which 817, 466, and 875 proteins were from Ad5-p54-, Ad5-p17-, Ad5-pB117L-infected 3D4/21 cells, respectively. Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed distinct yet interconnecting patterns of protein interaction networks. Specifically, the Ad5-p54 virus infection enriched the DEPs primarily involved in the metabolic pathways, endocytosis, adherens junction, and SNARE interactions in vesicular transport. The Ad5-p17 virus infection enriched the DEPs in endocytosis, ubiquitin-mediated proteolysis, N-Glycan biosynthesis, and apoptosis, while the Ad5-pB117L virus infection enriched the DEPs in metabolic pathways, endocytosis, oxidative phosphorylation, and focal adhesion. In summary, these results provide a comprehensive proteinomics analysis of the cellular responses to three ASFV membrane proteins, thus facilitating our understanding of ASFV pathogenesis.

[Application of microwave vacuum drying with process management in extract drying of personalized traditional Chinese medicine preparations].

Extracts are important intermediates in the production of traditional Chinese medicines preparations. The drying effect of extracts will directly affect the subsequent production process and the quality of the preparation. To meet the requirements of high drug loading, short time consumption, and simple production process of personalized traditional Chinese medicine preparations, this study explored the application of multi-program microwave vacuum drying process in the extract drying of personalized traditional Chinese medicine preparations. The influencing factors of microwave vacuum drying process were investigated for 5 excipients and 40 prescriptions. Taking the feasibility of drying, drying rate, drying time, and dried extract status as indicators, this study investigated the feeding requirements of microwave vacuum drying. With the dried extract status as the evaluation indicator, the three drying programs(A, B, and C) were compared to obtain the optimal drying condition. The experimental results showed that the optimal feeding conditions for microwave vacuum drying were material layer thickness of 2 cm and C program(a total of 7 drying processes), which solved the problem of easy scorching in microwave drying with process management. Furthermore, the preset moisture content of the dried extract in microwave drying should be 4%-5%, so that the dried extract of traditional Chinese medicine preparation had uniform quality, complete drying, and no scorching. This study lays a foundation for the application of microwave drying in the production of traditional Chinese medicine preparations, promoting the high-quality development of personalized traditional Chinese medicine preparations.

The crosstalk between macrophages and cancer cells potentiates pancreatic cancer cachexia.

With limited treatment options, cachexia remains a major challenge for patients with cancer. Characterizing the interplay between tumor cells and the immune microenvironment may help identify potential therapeutic targets for cancer cachexia. Herein, we investigate the critical role of macrophages in potentiating pancreatic cancer induced muscle wasting via promoting TWEAK (TNF-like weak inducer of apoptosis) secretion from the tumor. Specifically, depletion of macrophages reverses muscle degradation induced by tumor cells. Macrophages induce non-autonomous secretion of TWEAK through CCL5/TRAF6/NF-κB pathway. TWEAK promotes muscle atrophy by activating MuRF1 initiated muscle remodeling. Notably, tumor cells recruit and reprogram macrophages via the CCL2/CCR2 axis and disrupting the interplay between macrophages and tumor cells attenuates muscle wasting. Collectively, this study identifies a feedforward loop between pancreatic cancer cells and macrophages, underlying the non-autonomous activation of TWEAK secretion from tumor cells thereby providing promising therapeutic targets for pancreatic cancer cachexia.

Deficiency of Cbfß in articular cartilage leads to osteoarthritis-like phenotype through Hippo/Yap, TGFß, and Wnt/ß-catenin signaling pathways.

Osteoarthritis (OA) is the most prevalent degenerative joint disorder, causing physical impairments among the elderly. Core binding factor subunit ß (Cbfß) has a critical role in bone homeostasis and cartilage development. However, the function and mechanism of Cbfß in articular cartilage and OA remains unclear. We found that Cbfßf/fAggrecan-CreERT mice with Cbfß-deficiency in articular cartilage developed a spontaneous osteoarthritis-like phenotype with articular cartilage degradation. Immunofluorescence staining showed that Cbfßf/fAggrecan-CreERT mice exhibited a significant increase in the expression of articular cartilage degradation markers and inflammatory markers in the knee joints. RNA-sequencing analysis demonstrated that Cbfß orchestrated Hippo/Yap, TGFß/Smad, and Wnt/ß-catenin signaling pathways in articular cartilage, and Cbfß deficiency resulted in the abnormal expression of downstream genes involved in maintaining articular cartilage homeostasis. Immunofluorescence staining results showed Cbfß deficiency significantly increased active ß-catenin and TCF4 expression while reducing Yap, TGFß1, and p-Smad 2/3 expression. Western blot and qPCR validated gene expression changes in hip articular cartilage of Cbfß-deficient mice. Our results demonstrate that deficiency of Cbfß in articular cartilage leads to an OA-like phenotype via affecting Hippo/Yap, TGFß, and Wnt/ß-catenin signaling pathways, disrupting articular cartilage homeostasis and leading to the pathological process of OA in mice. Our results indicate that targeting Cbfß may be a potential therapeutic target for the design of novel and effective treatments for OA.

Incidence and Outcomes of Posterior Circulation Involvement in Moyamoya Disease.

BACKGROUND: Moyamoya disease (MMD) is a progressive, occlusive disease of the internal carotid arteries and their proximal branches, with the subsequent development of an abnormal vascular network that is rupture-prone. Steno-occlusive changes in the posterior cerebral arteries (PCAs) may contribute to worsened outcomes in patients with MMD; however, there is little information on the incidence and natural history of posterior circulation MMD (PCMMD). We describe clinical PCMMD characteristics in a large cohort of patients with MMD. METHODS: We retrospectively reviewed patients with MMD treated between 1991 and 2019 at a large academic medical center. Demographics, perioperative outcomes, and radiological phenotypes were recorded for 770 patients. PCA disease was graded as either 0 (no disease), 1 (mild), 2 (moderate), or 3 (severe or occluded) based on cerebral angiography. Patients with angiographically confirmed MMD diagnosis with at least 6 months follow-up and completion of revascularization surgery were included; patients with intracranial atherosclerosis, intracranial dissection, vasculitis, and undefined inflammatory processes were excluded. The presence of stenosis/occlusion was graded radiographically to assess for disease progression and the prevalence of risk factors related to reduced progression-free survival. RESULTS: In all, 686 patients met the inclusion criteria, with PCA disease identified in 282 (41.1%) patients. Of those 282 patients with PCMMD, disease severity ranged from 99 (35.1%) with mild, 72 (25.5%) with moderate, and 111 (39.4%) with severe. The total number of postoperative complications was significantly associated with PCMMD severity (P=0.0067). Additionally, PCMMD severity correlated with worse postoperative modified Rankin Scale scores (P<0.0001). At a mean follow-up of 6.0±3.9 (range, 0.1-25.0) years, a total of 60 (12.6%) patients showed new/worsening PCMMD. The overall postoperative, progression-free survival in patients with PCMMD was 95.4% at 1 year, 82.4% at 3 years, 68.8% at 5 years, and 28.3% at 10 years, with prognostic factors for progression including preoperative PCMMD status, history of tobacco use, and hypertension (P<0.0001, P<0.001, and P<0.0001, respectively). CONCLUSIONS: PCA disease involvement in MMD is associated with higher rates of ischemic perioperative complications and worsened functional outcomes, likely due to reduced collateral flow. Ten-year progression of PCA disease is highly likely and should be monitored throughout follow-up; future studies will assess the impact of PCA disease progression on long-term outcomes.

The role of DNA and RNA guanosine oxidation in cardiovascular diseases.

Cardiovascular diseases (CVD) persist as a prominent cause of mortality worldwide, with oxidative stress constituting a pivotal contributory element. The oxidative modification of guanosine, specifically 8-oxoguanine, has emerged as a crucial biomarker for oxidative stress, providing novel insights into the molecular underpinnings of CVD. 8-Oxoguanine can be directly generated at the DNA (8-oxo-dG) and RNA (8-oxo-G) levels, as well as at the free nucleotide level (8-oxo-dGTP or 8-oxo-GTP), which are produced and can be integrated through DNA replication or RNA transcription. When exposed to oxidative stress, guanine is more readily produced in RNA than in DNA. A burgeoning body of research surrounds 8-oxoguanine, exhibits its accumulation playing a pivotal role in the development of CVD. Therapeutic approaches targeting oxidative 8-Oxoguanine damage to DNA and RNA, encompassing the modulation of repair enzymes and the development of small molecule inhibitors, are anticipated to enhance CVD management. In conclusion, we explore the noteworthy elevation of 8-oxoguanine levels in patients with various cardiac conditions and deliberate upon the formation and regulation of 8-oxo-dG and 8-oxo-G under oxidative stress, as well as their function in CVD.

Ultrasound Trigger Ce-Based MOF Nanoenzyme For Efficient Thrombolytic Therapy.

The inflammatory damage caused by thrombus formation and dissolution can increase the risk of thrombotic complications on top of cell death and organ dysfunction caused by thrombus itself. Therefore, a rapid and precise thrombolytic therapy strategy is in urgent need to effectively dissolve thrombus and resist oxidation simultaneously. In this study, Ce-UiO-66, a cerium-based metal-organic framework (Ce-MOF) with reactive oxygen species (ROS) scavenging properties, encapsulated by low-immunogenic mesenchymal stem cell membrane with inflammation-targeting properties, is used to construct a targeted nanomedicine Ce-UiO-CM. Ce-UiO-CM is applied in combination with external ultrasound stimulation for thrombolytic therapy in rat femoral artery. Ce-UiO-66 has abundant Ce (III)/Ce (IV) coupling sites that react with hydrogen peroxide (H2O2) to produce oxygen, exhibiting catalase (CAT) activity. The multi-cavity structure of Ce-UiO-66 can generate electron holes, and its pore channels can act as micro-reactors to further enhance its ROS scavenging capacity. Additionally, the porous structure of Ce-UiO-66 and the oxygen produced by its reaction with H2O2 may enhance the cavitation effects of ultrasound, thereby improving thrombolysis efficacy.

Characterization and anti-aging activities of polysaccharide from Rana dybowskii Guenther.

Introduction: Rana dybowskii Guenther (RDG), as a traditional Chinese medicine, has been shown to have antioxidant effects. However, studies on the anti-aging effect of RDG are still limited. Methods: In this study, we prepared polysaccharides from the skin of RDG (RDGP) by hot water extraction, alcohol precipitation, ion-exchange chromatography and gel chromatography. The proteins were removed using the Sevage method in combination with an enzymatic method. The structural features were analyzed using high-performance gel permeation chromatography, ß-elimination reaction and Fourier transform infrared spectra. The anti-aging effect of RDGP was investigated by using D-Gal to establish an aging model in mice, and pathological changes in the hippocampus were observed under a microscope. Results: We obtained the crude polysaccharide DGP from the skin of RDG, with a yield of 61.8%. The free protein was then removed by the Sevage method to obtain DGPI and deproteinated by enzymatic hydrolysis combined with the Sevage method to further remove the bound protein to obtain the high-purity polysaccharide DGPII. Then, DGPIa (1.03 × 105 Da) and DGPIIa (8.42 × 104 Da) were obtained by gel chromatography, monosaccharide composition analysis showed that they were composed of Man, GlcA, GalNAc, Glc, Gal, Fuc with molar ratios of 1: 4.22 : 1.55: 0.18 : 8.05: 0.83 and 0.74 : 1.78: 1: 0.28: 5.37 : 0.36, respectively. The results of the ß-elimination reaction indicated the presence of O-glycopeptide bonds in DGPIa. The Morris water maze test indicated that mice treated with DGPIIa exhibited a significantly shorter escape latency and increased time spent in the target quadrant as well as an increase in the number of times they traversed the platform. Pathologic damage to the hippocampus was alleviated in brain tissue stained with hematoxylin-eosin. In addition, DGPIIa enhanced the activities of SOD, CAT, and GSH-Px and inhibited the level of MDA in the serum and brain tissues of aging mice. Discussion: These results suggest that RDGP has potential as a natural antioxidant and provide useful scientific information for anti-aging research.

Exposure to micron-grade silica particles triggers pulmonary fibrosis through cell-to-cell delivery of exosomal miR-107.

Long-term exposure to inhalable silica particles may lead to severe systemic pulmonary disease, such as silicosis. Exosomes have been demonstrated to dominate the pathogenesis of silicosis, but the underlying mechanisms remain unclear. Therefore, this study aimed to explore the roles of exosomes by transmitting miR-107, which has been linked to the toxic pulmonary effects of silica particles. We found that miR-107, miR-122-5p, miR-125a-5p, miR-126-5p, and miR-335-5p were elevated in exosomes extracted from the serum of patients with silicosis. Notably, an increase in miR-107 in serum exosomes and lung tissue was observed in the experimental silicosis mouse model, while the inhibition of miR-107 reduced pulmonary fibrosis. Moreover, exosomes helped the migration of miR-107 from macrophages to lung fibroblasts, triggering the transdifferentiation of cell phenotypes. Further experiments demonstrated that miR-107 targets CDK6 and suppresses the expression of retinoblastoma protein phosphorylation and E2F1, resulting in cell-cycle arrest. Overall, micron-grade silica particles induced lung fibrosis through exosomal miR-107 negatively regulating the cell cycle signaling pathway. These findings may open a new avenue for understanding how silicosis is regulated by exosome-mediated cell-to-cell communication and suggest the prospect of exosomes as therapeutic targets.

Correction: RNAi-Mediated Silencing of Atp6i and Atp6i Haploinsufficiency Prevents Both Bone Loss and Inflammation in a Mouse Model of Periodontal Disease.

[This corrects the article DOI: 10.1371/journal.pone.0058599.].

Decoding Microcystis aeruginosa quorum sensing through AHL-mediated transcriptomic molecular regulation mechanisms.

Acyl-homoserine lactone (AHL) serves as a key signaling molecule for quorum sensing (QS) in bacteria. QS-related genes and physiological processes in Microcystis aeruginosa remain elusive. In this study, we elucidated the regulatory role of AHL-mediated QS in M. aeruginosa. Using AHL activity extract and transcriptomic analysis, we revealed significant effects of the AHL on growth and photosynthesis. AHL significantly increased chlorophyll a (Chl-a) content and accelerated photosynthetic rate thereby promoting growth. Transcriptome analysis revealed that AHL stimulated the up-regulation of photosynthesis-related genes (apcABF, petE, psaBFK, psbUV, etc.) as well as nitrogen metabolism and ribosomal metabolism. In addition, AHL-regulated pathways are associated with lipopolysaccharide and phenazine synthesis. Our findings deepen the understanding of the QS system in M. aeruginosa and are important for gaining insights into the role of QS in Microcystis bloom formation. It also provides new insights into the prevalence of M. aeruginosa in water blooms.

An Assessment of Trends in HIV-1 Prevalence and Incidence and Spatio-Temporal Analyses of HIV-1 Recent Infection Among MSM During the Surveillance Period Between 2018 and 2022 in Sichuan, China.

Background: Men who have sex with men (MSM) is one main type of high-risk activities facilitating HIV-1 transmission in Sichuan province. Previous works on HIV-1 incidence and prevalence among MSM only concentrated before 2018, the situation after that is unknown. In addition, the distribution of hot-spots related to current HIV-1 epidemic is also rarely known among MSM in Sichuan. Objective: To update trends of HIV-1 prevalence and incidence and to visualize hot-spots of ongoing transmission in Sichuan province during surveillance period among MSM between 2018 and 2022. Methods: Limiting Antigen Avidity assay was performed to detect recent infection within new HIV-1 diagnoses founded during surveillance period among MSM. The HIV-1 prevalence and incidence were calculated according to an extrapolation method proposed by publications and guidelines. Trend tests were performed using χ2 tests with linear-by-linear association. The spatial analysis was conducted with ArcGIS 10.7 to figure hot-spots of HIV-1 recent infections among MSM. Results: Between 2018 and 2022, 16,697 individuals participated in HIV-1 MSM sentinel surveillance program, of which 449 samples (98.25%) were tested with LAg-Avidity EIA, and 230 samples were classified as recent infection. Respectively, the overall prevalence and incidence were 2.74% and 3.69% (95% CI: 3.21, 4.16) and both had significant declining trends (p < 0.001). Luzhou city had a highest HIV-1 incidence (10.74%, 95% CI: 8.39, 13.10) over the study period and was recognized as a hot-spot for recent HIV-1 infection among MSM. Conclusion: During the surveillance period, both HIV-1 prevalence and incidence were declining. However, Luzhou city had an unusually high HIV-1 incidence and became an emerging hot-spot of recent HIV-1 infection among MSM. This finding suggested focused attention, cross-regional intervention strategies, and prevention programs are urgently required to curb the spread of ongoing transmission.

Cysteine-Specific Multifaceted Bioconjugation of Peptides and Proteins Using 5-Substituted 1,2,3-Triazines.

Peptide and protein postmodification have gained significant attention due to their extensive impact on biomolecule engineering and drug discovery, of which cysteine-specific modification strategies are prominent due to their inherent nucleophilicity and low abundance. Herein, the study introduces a novel approach utilizing multifunctional 5-substituted 1,2,3-triazine derivatives to achieve multifaceted bioconjugation targeting cysteine-containing peptides and proteins. On the one hand, this represents an inaugural instance of employing 1,2,3-triazine in biomolecular-specific modification within a physiological solution. On the other hand, as a powerful combination of precision modification and biorthogonality, this strategy allows for the one-pot dual-orthogonal functionalization of biomolecules utilizing the aldehyde group generated simultaneously. 1,2,3-Triazine derivatives with diverse functional groups allow conjugation to peptides or proteins, while bi-triazines enable peptide cyclization and dimerization. The examination of the stability of bi-triazines revealed their potential for reversible peptide modification. This work establishes a comprehensive platform for identifying cysteine-selective modifications, providing new avenues for peptide-based drug development, protein bioconjugation, and chemical biology research.

One-Dimensional Covalent Organic Framework-Based Multilevel Memristors for Neuromorphic Computing.

Memristors are essential components of neuromorphic systems that mimic the synaptic plasticity observed in biological neurons. In this study, a novel approach employing one-dimensional covalent organic framework (1D COF) films was explored to enhance the performance of memristors. The unique structural and electronic properties of two 1D COF films (COF-4,4'-methylenedianiline (MDA) and COF-4,4'-oxydianiline (ODA)) offer advantages for multilevel resistive switching, which is a key feature in neuromorphic computing applications. By further introducing a TiO2 layer on the COF-ODA film, a built-in electric field between the COF-TiO2 interfaces could be generated, demonstrating the feasibility of utilizing COFs as a platform for constructing memristors with tunable resistive states. The 1D nanochannels of these COF structures contributed to the efficient modulation of electrical conductance, enabling precise control over synaptic weights in neuromorphic circuits. This study also investigated the potential of these COF-based memristors to achieve energy-efficient and high-density memory devices.

Thermal stratification and mixing processes response to meteorological factors in a monomictic reservoir.

Formation and extinction of thermal stratifications impact the reservoir ecosystems and have been closely influenced by meteorological and hydrological factors. However, quantifying the relative importance of these crucial environmental factors and mechanisms in reservoir regions characterized by various depths remain comparatively uninvestigated. Tianbao Reservoir is a typical monomictic warm and drinking water source reservoir in Southwest China. This study supplemented field observations with a three-dimensional numerical simulation model to quantitatively analyze mixing and turnover events. Air temperature and wind were two important meteorological factors resulting in hydrodynamics during stratification and mixing processes. Air temperature led to variations in stratification strength and wind-induced fluctuations of thermocline depth. A 10% rise in air temperature increased stratification strength by 18%, and a 3 m/s rise in wind speed induced the deepening of the thermocline by 2.09 m. Two hydrodynamics involved penetrative convection caused by temperature plummets and wind-induced mixing during winter turnover events were identified. Penetrative convection was the main driving force, and wind shear mixed the upper 21% of the mixed layer, which was contributed by convection. Response of water temperature to air temperature in shallow regions was faster (58 d), and the mixing depth caused by the wind was smaller than that in deep regions. Research on physical processes during stratification and mixing processes can provide support for further study on water quality deterioration distributions.

Influence of Strategic Crisis Communication on Public Perceptions during Public Health Crises: Insights from YouTube Chinese Media.

Crisis communication plays a crucial role in preserving the national reputation during significant national crises. From the perspective of Situational Crisis Communication Theory (SCCT), this research paper analyzed over 1,790,816 YouTube comments from Chinese-speaking audiences, using sentiment analysis alongside the Difference-in-Differences (DiD) model, in order to investigate the influence of strategic crisis communication on public perceptions during public health crises. The study findings indicate that during this public health crisis, YouTube Chinese media, whose audience mainly consists of overseas Chinese-speaking users, primarily incorporated the enhancing strategies, succeeded by the diminish strategies, with limited application of deny strategies, while the use of rebuild strategies was virtually absent in this context. In addition, the research analysis confirms that Chinese media effectively increased the public's positive perceptions of crisis events through crisis communication. Particularly, enhancing strategies proved most effective in improving public perceptions, followed by diminish strategies. In contrast, deny strategies failed to influence public perceptions of the crisis, and rebuild strategies demonstrated a negative impact on public perception. Thus, the research findings of this paper extend essential insights for effectively managing potential public health crises in the future.

SARS-CoV-2 spike-reactive naïve B cells and pre-existing memory B cells contribute to antibody responses in unexposed individuals after vaccination.

Introduction: Since December 2019, the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) has presented considerable public health challenges. Multiple vaccines have been used to induce neutralizing antibodies (nAbs) and memory B-cell responses against the viral spike (S) glycoprotein, and many essential epitopes have been defined. Previous reports have identified severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike-reactive naïve B cells and preexisting memory B cells in unexposed individuals. However, the role of these spike-reactive B cells in vaccine-induced immunity remains unknown. Methods: To elucidate the characteristics of preexisting SARS-CoV-2 S-reactive B cells as well as their maturation after antigen encounter, we assessed the relationship of spike-reactive B cells before and after vaccination in unexposed human individuals. We further characterized the sequence identity, targeting domain, broad-spectrum binding activity and neutralizing activity of these SARS-CoV-2 S-reactive B cells by isolating monoclonal antibodies (mAbs) from these B cells. Results: The frequencies of both spike-reactive naïve B cells and preexisting memory B cells before vaccination correlated with the frequencies of spike-reactive memory B cells after vaccination. Isolated mAbs from spike-reactive naïve B cells before vaccination had fewer somatic hypermutations (SHMs) than mAbs isolated from spike-reactive memory B cells before and after vaccination, but bound SARS-CoV-2 spike in vitro. Intriguingly, these germline-like mAbs possessed broad binding profiles for SARS-CoV-2 and its variants, although with low or no neutralizing capacity. According to tracking of the evolution of IGHV4-4/IGKV3-20 lineage antibodies from a single donor, the lineage underwent SHMs and developed increased binding activity after vaccination. Discussion: Our findings suggest that spike-reactive naïve B cells can be expanded and matured by vaccination and cocontribute to vaccine-elicited antibody responses with preexisting memory B cells. Selectively and precisely targeting spike-reactive B cells by rational antigen design may provide a novel strategy for next-generation SARS-CoV-2 vaccine development.

Tissue-specific profiling of age-dependent miRNAomic changes in Caenorhabditis elegans.

Ageing exhibits common and distinct features in various tissues, making it critical to decipher the tissue-specific ageing mechanisms. MiRNAs are essential regulators in ageing and are recently highlighted as a class of intercellular messengers. However, little is known about the tissue-specific transcriptomic changes of miRNAs during ageing. C. elegans is a well-established model organism in ageing research. Here, we profile the age-dependent miRNAomic changes in five isolated worm tissues. Besides the diverse ageing-regulated miRNA expression across tissues, we discover numerous miRNAs in the tissues without their transcription. We further profile miRNAs in the extracellular vesicles and find that worm miRNAs undergo inter-tissue trafficking via these vesicles in an age-dependent manner. Using these datasets, we uncover the interaction between body wall muscle-derived mir-1 and DAF-16/FOXO in the intestine, suggesting mir-1 as a messenger in inter-tissue signalling. Taken together, we systematically investigate worm miRNAs in the somatic tissues and extracellular vesicles during ageing, providing a valuable resource to study tissue-autonomous and nonautonomous functions of miRNAs in ageing.