Evolution for improved secretion and fitness may be the selective pressures leading to the emergence of two NDM alleles

The potential of Gynostemma pentaphyllum in the treatment of hyperlipidemia and its interaction with the LOX1-PI3K-AKT-eNOS pathway

Gynostemma pentaphyllum, a traditional Chinese medicine, is widely used to treat various diseases, but its therapeutic effects and mechanisms of action on hyperlipidemia remain unclear. This study aims to investigate the effects of Danshen leaf on hyperlipidemia through network pharmacology, molecular docking, and cellular experiments, elucidating its multifaceted mechanism of action within the LOX1-PI3K-AKT-eNOS pathway. First, the active ingredients and targets of G. pentaphyllum were screened using the Traditional Chinese Medicine Systems Pharmacology database. Then, targets for hyperlipidemia were identified using the OMIM and GeneCards databases, and potential therapeutic targets for G. pentaphyllum in treating hyperlipidemia were determined. An active ingredient-target network was constructed using Cytoscape software, and a protein-protein interaction (PPI) network was built and visualized using the STRING database and Cytoscape software. Finally, GO functional and KEGG pathway enrichment analyses were performed, and the predicted mechanisms were validated through molecular docking and cell experiments. 85 targets for G. pentaphyllum and 1556 for Hyperlipidemia were screened, with 53 common targets. Twenty-four active ingredients of G. pentaphyllum were found to be involved in the treatment of hyperlipidemia. Key nodes such as Rhamnazin, Isofucosterol, and quercetin, and targets NCOA2, NR3C2, PGR, and PPARG showed high relevance. In the PPI network, 8 nodes, including IL6, PPARG, and VEGFA, exhibited high centrality. GO functional and KEGG pathway enrichment analyses indicated that G. pentaphyllum may treat hyperlipidemia by influencing various biological functions and pathways, such as DNA-binding transcription factor binding, RNA polymerase II-specific DNA-binding transcription factor binding, and lipid and atherosclerosis. Cell experiments demonstrated that G. pentaphyllum significantly regulated the expression of key proteins in the LOX1-PI3K-AKT-eNOS pathway, thereby improving hyperlipidemia. G. pentaphyllum improves hyperlipidemia by mediating the LOX1-PI3K-AKT-eNOS pathway. This study provides a new theoretical basis and experimental evidence for applying G. pentaphyllum to treating hyperlipidemia.

Novel partially reversible NDM-1 inhibitors based on the naturally occurring houttuynin

Discovering novel NDM-1 inhibitors is an urgent task for treatment of 'superbug' infectious diseases. In this study, we found that naturally occurring houttuynin and its sulfonate derivatives might be effective NDM-1 inhibitors with novel mechanism, i.e. the attribute of partially covalent inhibition of sulfonate derivatives of houttuynin against NDM-1. Primary structure-activity relationship study showed that both the long aliphatic side chain and the warhead of aldehyde group are vital for the efficiency against NDM-1. The homologs with longer chains (SNH-2 to SNH-5) displayed stronger inhibitory activities with IC50 range of 1.1-1.5 μM, while the shorter chain the weaker inhibition. Further synergistic experiments in cell level confirmed that all these 4 compounds (at 32 μg/mL) recovered the antibacterial activity of meropenem (MER) against E. coli BL21/pET15b-blaNDM-1.

Understanding blaNDM-1 gene regulation in CRKP infections: toward novel antimicrobial strategies for hospital-acquired pneumonia

BACKGROUND

The escalating challenge of Carbapenem-resistant Klebsiella pneumoniae (CRKP) in hospital-acquired pneumonia (HAP) is closely linked to the blaNDM-1 gene. This study explores the regulatory mechanisms of blaNDM-1 expression and aims to enhance antibacterial tactics to counteract the spread and infection of resistant bacteria.

METHODS

KP and CRKP strains were isolated from HAP patients' blood samples. Transcriptomic sequencing (RNA-seq) identified significant upregulation of blaNDM-1 gene expression in CRKP strains. Bioinformatics analysis revealed blaNDM-1 gene involvement in beta-lactam resistance pathways. CRISPR-Cas9 was used to delete the blaNDM-1 gene, restoring sensitivity. In vitro and in vivo experiments demonstrated enhanced efficacy with Imipenem and Thanatin or Subatan combination therapy.

RESULTS

KP and CRKP strains were isolated with significant upregulation of blaNDM-1 in CRKP strains identified by RNA-seq. The Beta-lactam resistance pathway was implicated in bioinformatics analysis. Knockout of blaNDM-1 reinstated sensitivity in CRKP strains. Further, co-treatment with Imipenem, Thanatin, or Subactam markedly improved antimicrobial effectiveness.

CONCLUSION

Silencing blaNDM-1 in CRKP strains from HAP patients weakens their Carbapenem resistance and optimizes antibacterial strategies. These results provide new theoretical insights and practical methods for treating resistant bacterial infections.

Phasevarions in Haemophilus influenzae biogroup aegyptius control expression of multiple proteins

IMPORTANCE

Haemophilus influenzae biogroup aegyptius is a human-adapted pathogen and the causative agent of Brazilian purpuric fever (BPF), an invasive disease with high mortality, that sporadically manifests in children previously suffering conjunctivitis. Phase variation is a rapid and reversible switching of gene expression found in many bacterial species, and typically associated with outer-membrane proteins. Phase variation of cytoplasmic DNA methyltransferases has been shown to play important roles in bacterial gene regulation and can act as epigenetic switches, regulating the expression of multiple genes as part of systems called phasevarions (phase-variable regulons). This study characterized two alleles of the ModA phasevarion present in H. influenzae biogroup aegyptius, ModA13, found in non-BPF causing strains and ModA16, unique to BPF causing isolates. Phase variation of ModA13 and ModA16 led to genome-wide changes to DNA methylation resulting in altered protein expression. These changes did not affect serum resistance in H. influenzae biogroup aegyptius strains.

Metallo-β-lactamases in the Age of Multidrug Resistance: From Structure and Mechanism to Evolution, Dissemination, and Inhibitor Design

Antimicrobial resistance is one of the major problems in current practical medicine. The spread of genes coding for resistance determinants among bacteria challenges the use of approved antibiotics, narrowing the options for treatment. Resistance to carbapenems, last resort antibiotics, is a major concern. Metallo-β-lactamases (MBLs) hydrolyze carbapenems, penicillins, and cephalosporins, becoming central to this problem. These enzymes diverge with respect to serine-β-lactamases by exhibiting a different fold, active site, and catalytic features. Elucidating their catalytic mechanism has been a big challenge in the field that has limited the development of useful inhibitors. This review covers exhaustively the details of the active-site chemistries, the diversity of MBL alleles, the catalytic mechanism against different substrates, and how this information has helped developing inhibitors. We also discuss here different aspects critical to understand the success of MBLs in conferring resistance: the molecular determinants of their dissemination, their cell physiology, from the biogenesis to the processing involved in the transit to the periplasm, and the uptake of the Zn(II) ions upon metal starvation conditions, such as those encountered during an infection. In this regard, the chemical, biochemical and microbiological aspects provide an integrative view of the current knowledge of MBLs.