Norwogonin aids in fighting MRSA-induced pneumonia by targeting agrAC to inhibit α-hemolysin production.

The increasing prevalence of infections related to methicillin-resistant Staphylococcus aureus (MRSA) necessitates the exploration of innovative therapeutic strategies that diverge from conventional antibiotic treatments. This is imperative to effectively combat resistance and manage these infections. The adoption of antivirulence strategies has emerged as a particularly promising avenue. This approach applies a heightened selective pressure on pathogens, thereby diminishing the likelihood of bacteria evolving resistance to antibiotics. In our pursuit of novel therapeutics for treating MRSA infections, we have focused on agents that inhibit the virulence of S. aureus without impeding its growth, aiming to minimize the development of drug resistance. α-Hemolysin, a critical virulence factor encoded by the hla gene, is a cytotoxin that forms pores in host cell membranes and plays a pivotal role in the progression of disease during bacterial infections. Herein, we identified that norwogonin could effectively inhibit Hla production via targeting agrAC, a crucial protein in quorum sensing, resulting in dose-dependent inhibition of hemolytic activity without suppressing S. aureus growth. In vitro assays illustrated that norwogonin decreased the thermal stability of agrAC, providing evidence of interaction between norwogonin and agrAC. Meanwhile, norwogonin alleviated Hla-mediated A549 cell damage and reduced lactate dehydrogenase release. In vivo studies suggested that norwogonin treatment blocked the establishment of a mouse model of pneumonia caused by S. aureus USA300. Notably, norwogonin enhanced the antibacterial potency of oxacillin. In conclusion, norwogonin is a promising candidate for treating S. aureus infections, offering a novel alternative to traditional antibiotics by targeting virulence factors and enhancing the efficacy of existing treatments.

Tamarixetin Attenuated the Virulence of Staphylococcus aureus by Directly Targeting Caseinolytic Protease P.

Staphylococcus aureus, especially drug-resistant S. aureus infections, is a worldwide healthcare challenge. There is a growing focus on antivirulence therapy against S. aureus. Caseinolytic protease p (ClpP) is a protein hydrolase essential for pathogenicity in S. aureus. A flavonoid compound, tamarixetin, which was screened in this work, was specifically able to inhibit the hydrolytic activity of ClpP on the fluorescent substrate Suc-LY-AMC with an IC50 of 49.73 µM, without affecting the growth of methicillin-resistant S. aureus strain USA300 and was without obvious cytotoxicity. Further assays found that tamarixetin inhibited the transcription of hla, agr, RNAIII, pvl, PSM-α, and spa genes as well as suppressed the protein expression levels of Hla and PVL. Moreover, tamarixetin was observed to dramatically inhibit the hemolytic activity of hla in S. aureus. Consistent with that of S. aureus USA300-ΔclpP, tamarixetin was shown to increase urease expression. The thermal shift and cellular thermal shift assays showed that tamarixetin markedly changed the thermal stability of ClpP. The dissociation constant (KD) value of tamarixetin with ClpP was 2.52 × 10-6 M measured by surface plasmon resonance. The molecular docking and ClpP point mutation results also demonstrated that tamarixetin had a strong interaction with ClpP. In vivo study showed that tamarixetin was effective in protecting mice from S. aureus pneumonia by increasing survival, reducing lung tissue load, and slowing down the infiltration of inflammatory factors. In addition, tamarixetin was able to enhance the antibacterial activity of cefotaxime in combination. In conclusion, tamarixetin was promising as a ClpP inhibitor for S. aureus infections.

7,8-Dihydroxyflavone attenuates the virulence of Staphylococcus aureus by inhibiting alpha-hemolysin.

Staphylococcus aureus (S. aureus), a Gram-positive bacteria, is an incurable cause of hospital and community-acquired infections. Inhibition bacterial virulence is a viable strategy against S. aureus infections based on the multiple virulence factors secreted by S. aureus. Alpha-hemolysin (Hla) plays a crucial role in bacteria virulence without affecting bacterial viability. Here, we identified that 7,8-Dihydroxyflavone (7,8-DHF), a natural compound, was able to decrease the expression of and did not affect the in vitro growth of S. aureus USA300 at a concentration of 32 µg/mL. It was verified by western blot and RT-qPCR that the natural compound could inhibit the transcription and translation of Hla. Further mechanism studies revealed that 7,8-DHF has a negative effect on transcriptional regulator agrA and RNAIII, preventing the upregulation of virulence gene. Cytotoxicity assays showed that 7,8-DHF did not produce significant cytotoxicity to A549 cells. Animal experiments showed that the combination of 7,8-DHF and vancomycin had a more significant therapeutic effect on S. aureus infection, reflecting the synergistic effect of 7,8-DHF with antibiotics. In conclusion, 7,8-DHF was able to target Hla to protect host cells from hemolysis while limiting the development of bacterial resistance.

Novel Pyrazole-4-Carboxamide Derivatives Containing Oxime Ether Group as Potential SDHIs to Control Rhizoctonia solani.

In the search for novel succinate dehydrogenase inhibitor (SDHI) fungicides to control Rhizoctonia solani, thirty-five novel pyrazole-4-carboxamides bearing either an oxime ether or an oxime ester group were designed and prepared based on the strategy of molecular hybridization, and their antifungal activities against five plant pathogenic fungi were also investigated. The results indicated that the majority of the compounds containing oxime ether demonstrated outstanding in vitro antifungal activity against R. solani, and some compounds also displayed pronounced antifungal activities against Sclerotinia sclerotiorum and Botrytis cinerea. Particularly, compound 5e exhibited the most promising antifungal activity against R. solani with an EC50 value of 0.039 µg/mL, which was about 20-fold better than that of boscalid (EC50 = 0.799 µg/mL) and 4-fold more potent than fluxapyroxad (EC50 = 0.131 µg/mL). Moreover, the results of the detached leaf assay showed that compound 5e could suppress the growth of R. solani in rice leaves with significant protective efficacies (86.8%) at 100 µg/mL, superior to boscalid (68.1%) and fluxapyroxad (80.6%), indicating promising application prospects. In addition, the succinate dehydrogenase (SDH) enzymatic inhibition assay revealed that compound 5e generated remarkable SDH inhibition (IC50 = 2.04 µM), which was obviously more potent than those of boscalid (IC50 = 7.92 µM) and fluxapyroxad (IC50 = 6.15 µM). Furthermore, SEM analysis showed that compound 5e caused a remarkable disruption to the characteristic structure and morphology of R. solani hyphae, resulting in significant damage. The molecular docking analysis demonstrated that compound 5e could fit into the identical binding pocket of SDH through hydrogen bond interactions as well as fluxapyroxad, indicating that they had a similar antifungal mechanism. The density functional theory and electrostatic potential calculations provided useful information regarding electron distribution and electron transfer, which contributed to understanding the structural features and antifungal mechanism of the lead compound. These findings suggested that compound 5e could be a promising candidate for SDHI fungicides to control R. solani, warranting further investigation.

Effects of plastic aging on biodegradation of polystyrene by Tenebrio molitor larvae: Insights into gut microbiome and bacterial metabolism.

Plastics aging reduces resistance to microbial degradation. Plastivore Tenebrio molitor rapidly biodegrades polystyrene (PS, size: < 80 µm), but the effects of aging on PS biodegradation by T. molitor remain uncharacterized. This study examined PS biodegradation over 24 days following three pre-treatments: freezing with UV exposure (PS1), UV exposure (PS2), and freezing (PS3), compared to pristine PS (PSv) microplastic. The pretreatments deteriorated PS polymers, resulting in slightly higher specific PS consumption (602.8, 586.1, 566.7, and 563.9 mg PS·100 larvae-1·d-1, respectively) and mass reduction rates (49.6 %, 49.5 %, 49.2 %, and 48.7 %, respectively) in PS1, PS2, and PS3 compared to PSv. Improved biodegradation correlated with reduced molecular weights and the formation of oxidized functional groups. Larvae fed more aged PS exhibited greater gut microbial diversity, with microbial community and metabolic pathways shaped by PS aging, as supported by co-occurrence network analysis. These findings indicated that the aging treatments enhanced PS biodegradation by only limited extent but impacted greater on gut microbiome and bacterial metabolic genes, indicating that the T. molitor host have highly predominant capability to digest PS plastics and alters gut microbiome to adapt the PS polymers fed to them.

Effects of magnolol on impairment of learning and memory abilities induced by scopolamine in mice.

Alzheimer's disease (AD), one of the most common forms of dementia, is primarily ascribed to the cholinergic deficits and neuronal dysfunction. Magnolol (Mag), a bioactivator extracted from Magnolia officinalis, has protective effects on cholinergic neurons, but the specific mechanism remains unknown. To further evaluate the therapeutic effects of Mag on the learning and memory impairment in a scopolamine (Scop)-induced mouse model, the passive avoidance and the Morris water maze tests, the measurement of the ratio of brain/hippocampus to body weight, activities of acetyl cholinesterase (AChE), superoxide dismutase (SOD), total nitric oxide synthase (total NOS) and the content of methane dicarboxylic aldehyde (MDA) in hippocampus homogenate as well as the immunefluorescence staining of the AChE positive nerve fibers were performed. Therapeutically treated with Mag, the impaired abilities of learning and memory of the Scop-induced mice were almost restored to the native levels. The restored AChE, total NOS and SOD activities and the MDA level were observed, with a relatively normal density of AChE positive nerve fibers in hippocampus CA3 molecular layer. The improving efficacy of Mag on learning and memory impairment induced by Scop is dose-dependent, indicating that Mag has potential neuroprotective effects against neuronal impairment and memory dysfunction induced by Scop in mice. The underlying mechanisms may be associated with the anti-oxidative effects of Mag and its protective effects on hippocampus cholinergic neurons.

Professional commitment and related factors among nursing undergraduates: A latent profile analysis.

OBJECTIVE: To identify different subgroups of nursing professional commitment among nursing undergraduates and to analyze the related factors of the different subgroups. METHODS: A cross-sectional study using the professional commitment scale with 430 nursing undergraduates was conducted. Latent profile analysis was used to explore the nursing students' professional commitment subgroups and using multivariate logistic regression to analyze the related factors of nursing professional commitment. RESULTS: The overall mean score for professional commitment in nursing was (75.07 ± 14.715). There were three different subgroups of professional commitment characteristics, namely the "high professional commitment group" (20.465 %), the "medium professional commitment group" (66.279 %), and the "low professional commitment group" (13.256 %). Dissatisfaction with clinical placement (OR = 3.556, p = 0.008) and self-enrollment (OR = 0.186, p = 0.002) were significantly related factors for low-level and medium-level nursing commitment groups. Students' origin in western China (OR = 1.869, p = 0.042) significantly influenced the medium-level specialty commitment group. CONCLUSIONS: Most nursing undergraduates have been categorized in the "medium professional commitment group". Students who were dissatisfied with their clinical experience and chose the nursing profession involuntarily were the main factors for low-level and medium-level nursing professional commitment. The clinical practice environment should be further improved to enhance the clinical experience satisfaction of nursing undergraduates; at the same time, the professional value cultivation of students whose choice of nursing profession was not made by themselves should be strengthened to improve the level of professional commitment of nursing undergraduates.

Bavachin Suppresses Alpha-Hemolysin Expression and Protects Mice from Pneumonia Infection by Staphylococcus aureus.

Staphylococcus aureus (S. aureus) infection causes dramatic harm to human health as well as to livestock development. As an important virulence factor, alpha-hemolysin (hla) is critical in the process of S. aureus infection. In this report, we found that bavachin, a natural flavonoid, not only efficiently inhibited the hemolytic activity of hla, but was also capable of inhibiting it on transcriptional and translational levels. Moreover, further data revealed that bavachin had no neutralizing activity on hla, which did not affect the formation of hla heptamers and exhibited no effects on the hla thermal stability. In vitro assays showed that bavachin was able to reduce the S. aureus-induced damage of A549 cells. Thus, bavachin repressed the lethality of pneumonia infection, lung bacterial load and lung tissue inflammation in mice, providing potent protection to mice models in vivo. Our results indicated that bavachin has the potential for development as a candidate hla inhibitor against S. aureus.

Natural flavone hispidulin protects mice from Staphylococcus aureus pneumonia by inhibition of α-hemolysin production via targeting AgrAC.

The emergence of drug-resistant Staphylococcus aureus (S. aureus) has limited drug options for the clinical treatment of S. aureus infections. Considering recent reports, therapeutic strategies targeting bacterial virulence hold great promise, and alpha-hemolysin (encoded by hla), a critical virulence factor of S. aureus, plays a vital role during bacterial infection. Herein, we demonstrated that hispidulin effectively inhibited the hemolytic activity of S. aureus USA300 without suppressing bacterial growth, along with inhibiting hla transcription and expression in a dose-dependent manner. As heptamer formation is essential for hla-mediated invasion of cells, nevertheless, hispidulin did not affect the deoxycholate-induced oligomerization of hla, suggesting that hispidulin did not affect the protein activity of hla. In vitro assays illustrated that hispidulin bound to agrAC, a crucial protein in quorum sensing. Meanwhile, hispidulin alleviated A549 cell damage caused by S. aureus USA300 and reduced lactate dehydrogenase release. In vivo studies showed that hispidulin had a protective effect against pneumonia caused by S. aureus USA300 in mice. S. aureus did not develop resistance to hispidulin in the short term. Interestingly, our research indicated that hispidulin synergized with the antibacterial activity of cefoxitin. These results showed that hispidulin effectively inhibited α-hemolysin expression by inhibiting the agr quorum sensing of S. aureus. It has promise as an agent to treat S. aureus infection.

Corrigendum: Pharmacokinetics, Immunogenicity and Safety Study for SHR-1309 Injection and Perjeta® in Healthy Chinese Male Volunteers.

[This corrects the article DOI: 10.3389/fphar.2021.660541.].

A randomized, double-blind, single-dose, two-way, parallel phase I clinical study comparing the pharmacokinetics and safety of adalimumab injecta and Humira® in healthy Chinese male volunteers.

BACKGROUND: Humira® is a fully humanized anti-tumor necrosis factor (TNF-α) monoclonal antibody that has been marketed and approved in the United States for the clinical treatment of rheumatoid arthritis (RA), ankylosing spondylitis, psoriasis and other immune-mediated diseases. This study compared the bioequivalence, immunogenicity and safety of adalimumab injecta (a biosimilar of Humira® produced by Chia Tai Tianqing Pharmaceutical Group Co., Ltd) and Humira® in healthy Chinese male subjects in a phase I clinical study. METHODS: Healthy Chinese male subjects (N = 164) were randomly given a subcutaneous injection of 40 mg adalimumab or Humira® at a 1:1 ratio. Plasma drug concentrations were detected by enzyme-linked immunosorbent assay (ELISA), and primary pharmacokinetic (PK) parameters were statistically analyzed. To evaluate drug immunogenicity, anti-drug antibody (ADA) and neutralizing antibody (nAb) levels were detected. To evaluate the safety of the drugs, the subjects' physical indicators, such as multiple vital signs and routine blood tests, were continuously monitored. RESULTS: The similarity ratios of adalimumab and Humira® PK parameters were all within 80%-125%, meeting the bioequivalence standards. Drug-induced ADA and nAb levels were similar, and the drug safety in subjects was also similar. CONCLUSIONS: All study drugs showed similar bioequivalence, immunogenicity and safety. CLINICAL TRIAL REGISTRATION: CTR20182070 (Chinese Clinical Trial Registry).

Nepetin reduces virulence factors expression by targeting ClpP against MRSA-induced pneumonia infection.

The resistance of Staphylococcus aureus (S. aureus) to various antibiotics has increased dramatically due to the misuse of antibiotics, and thus the development of new anti-infective drugs with new targets is urgently needed to combat resistance. Caseinolytic peptidase P is a case in hydrolase that regulates the virulence level of S. aureus. Here, we found that nepetin, a small-molecule compound from traditional Chinese herbal flavonoids, effectively inhibits ClpP activity. Nepetin suppressed the virulence of S. aureus and effectively combated the lethal pneumonia caused by MRSA. The results of cellular thermal shift assay showed that nepetin could bind to ClpP and reduce the thermal stability of ClpP, and the KD value of 602 nM between them was determined using localized surface plasmon resonance. The binding mode of nepetin and ClpP was further investigated by molecular docking, and it was found that Ser-22 and Gln-47 of ClpP residues were found to be involved in the binding of nepetin to ClpP. In conclusion, we determined that nepetin is a ClpP inhibitor and an effective lead compound for the development of a virulence factor-based treatment for MRSA infection.

Impacts of physical-chemical property of polyethylene on depolymerization and biodegradation in yellow and dark mealworms with high purity microplastics.

Yellow and dark mealworms (Tenebrio molitor and Tenebrio obscurus) biodegrade commercial polyethylene (PE) materials at a high rate. We examined the impact of physical and chemical properties on biodegradation using high purity microplastics (MPs). These included high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE), all with different weight average molecular weights (Mw) and different crystallinity degrees in T. molitor and T. obscurus larvae. The biodegradation extent in the two mealworms was similar but strongly depended on the polymer type in sequence, since LDPE > LLDPE> HDPE (with respective Mw of 222.5, 110.5 and 182 kDa). When LDPE MPs with Mw of 0.84, 6.4 and 106.8 kDa and HDPE with Mw of 52, 105 and 132.7 kDa were tested, the PE MPs with lower Mw showed a greater extent of depolymerization. The results of dominance analysis indicated that less branching structure and higher crystallinity degree negatively impacted depolymerization and biodegradation. Py-GC/MS analysis confirmed the breaking of the macromolecule backbone as well as the formation of oxidized functional groups after all the tested PE materials passed through the mealworm intestine. The results demonstrated that molecular weight, PE type, branching, and crystallinity degree significantly affect the biodegradation capability of PE by the mealworms, and possibly by other biological systems as well.

Pharmacokinetics, Immunogenicity and Safety Study for SHR-1309 Injection and Perjeta® in Healthy Chinese Male Volunteers.

Objectives: Pertuzumab is a monoclonal antibody for the treatment of breast cancer. The aim of this study was to compare the pharmacokinetics, immunogenicity and safety of the test preparation SHR-1309 injecta and the reference preparation Perjeta® in healthy Chinese male subjects. Methods: In this randomized, double-blind, single dose, two-way, parallel bioequivalence trial, a total of 80 qualified Chinese male subjects were selected and randomly divided into two groups. Each subject was intravenously injected with SHR-1309 or Perjeta®. Blood samples were collected at 21 different time points for pharmacokinetic analysis. In addition, immunogenicity was assessed at five different time points. The safety of the medication was monitored throughout the whole trial. Results: Cmax and AUC0-t were the primary pharmacokinetic parameters. Under a 90% confidence interval, their geometric mean ratios were 98.30 and 88.41% for SHR-1309 injection and Perjeta®, respectively. The geometric mean ratio of secondary pharmacokinetic parameters AUC0-∞ was 88.58%. These evaluation indexes are in the standard range of 80-125%, so SHR-1309 can be considered bioequivalent to Perjeta®. After 1,680 h (day 70) of administration, the two groups had 12 and 13 subjects who produced antidrug antibody (ADA), respectively. The occurrence time and proportion of ADA in SHR-1309 and Perjeta® were similar between subjects, and they had similar immunogenicity. During the entire trial period, there were 71 drug-related adverse reactions in 29 subjects who received SHR-1309 and 61 drug-related adverse reactions in 32 subjects who received Perjeta®. The incidence of adverse reactions between the two drugs was similar. Conclusion: The pharmacokinetic parameters, immunogenicity and safety of the biosimilar SHR-1309 injection produced by Shanghai Hengrui Pharmaceutical Co. Ltd. were similar to the original drug Perjeta® produced by Roche Pharma AG. The two drugs met the bioequivalence evaluation criteria. Therefore, SHR-1309 is bioequivalent to Perjeta®. Clinical trial registration: CTR20200,738.

Tetrahedral Framework Nucleic Acid Delivered RNA Therapeutics Significantly Attenuate Pancreatic Cancer Progression via Inhibition of CTR1-Dependent Copper Absorption.

Copper is vital for various life processes, whereas severely toxic at excess level. Intracellular copper homeostasis is strictly controlled by a set of transporters and chaperones encoded by the copper homeostasis genes. Increasing evidence has shown that copper is usually overloaded in multiple malignancies, including pancreatic cancer, which has an extremely poor prognosis. Recently, silencing the SLC31A1 gene, which encodes a major transmembrane copper transporter (CTR1), has been demonstrated to be an effective means for reducing the malignant degree of pancreatic cancer by downregulating the cellular copper levels. Herein, we utilized tetrahedral framework nucleic acids (tFNAs) as vehicles to overcome the biological barriers for delivering small molecular RNAs and efficiently transferred two kinds of CTR1 mRNA-targeted RNA therapeutics, siCTR1 or miR-124, into PANC-1 cells. Both therapeutic tFNAs, termed t-siCTR1 and t-miR-124, prevented copper intake more effective than the free RNA therapeutics via efficiently suppressing the expression of CTR1, thereby significantly attenuating the progression of PANC-1 cells. In this study, therapeutic tFNAs are constructed to target metal ion transporters for the first time, which may provide an effective strategy for future treatment of other metal metabolism disorders.