ACS Infectious Diseases最新文献

Chagas disease (CD), caused by Trypanosoma cruzi, has been one of the leading causes of cardiac death in Latin America. Its pathogenesis and progression are still poorly understood. Thus, we performed an untargeted metabolomics analysis to understand the metabolic changes involved in the final acute phase of CD. Male mice’s chagasic hearts (60 days postinfection) were compared to healthy tissues. Two hundred and fifty-one significant metabolites or chemical classes were annotated. Disturbances in energy metabolism and dysregulation of amino acids were observed. Pathway analyses indicated increased inflammatory activity in infected individuals, as observed by eicosanoid (prostaglandin and thromboxane) changes. The accumulation of some sphingomyelins, correlated with myocarditis, suggests heart tissue damage from the infection. The metabolic changes observed contribute to understanding disease progression and the cardiac effects caused by the parasite, bringing new insights into the discovery and development of new therapies.

Streptococcus gordonii sp. firmicutes is an early colonizer of the oral microbiome and contributes positively to oral health. While this species has been found to produce hydrogen peroxide by spxB expression, the relationship of this expression to the competence regulon has not yet been explored. To this end, this study sought to investigate the connection of the S. gordonii competence regulon quorum sensing (QS) circuitry with downstream proliferative phenotypic expression resulting from competence-stimulating peptide (CSP) exposure, with specific attention to peroxide formation. Following confirmation of the native CSP, RNA-seq was completed to gain insights into transcriptomic variations resulting from CSP incubation. Later, structure–activity relationship (SAR) analyses of the native CSP were completed. The results revealed residues integral to CSP:ComD binding and activation, while indicating which residues were considered dispensable to this process. Phenotypic assessment revealed that peroxide formation was modulated via the competence regulon. Finally, interspecies competition assays were carried out to understand the interactions between S. gordonii and S. mutans, with S. gordonii demonstrating a profound capability of antagonizing S. mutans growth and proliferation. Our results support that this antagonism is mainly attributed to hydrogen peroxide production by S. gordonii. This finding suggests that S. gordonii may be exploited for its beneficial proliferative phenotypes downstream of the competence regulon.

Crassostrea gigas big defensins (Cg-BigDefs) are a family of two-domain antimicrobial peptides with broad antibacterial activity. The C-terminal domain of Cg-BigDefs harbors a β-defensin-like structure, whereas the ancestral N-terminal domain adopts a globular structure. Here, we developed molecular tools to track the fine interactions of these two domains with Staphylococcus aureus and to gain insight into Cg-BigDef1 mechanisms of action. By using super-resolution microscopy and S. aureus mutants with specific deletions of cell wall components, we found that teichoic acids (TAs) play a key role in the Cg-BigDef1 interaction with S. aureus. A ΔtagO S. aureus mutant lacking cell wall teichoic acids (WTAs) exhibited increased resistance to Cg-BigDef1. Consistently, the binding of Cg-BigDef1 to S. aureus cell wall was significantly reduced in the ΔtagO mutant. In contrast, a ΔdltA S. aureus mutant unable to transfer d-alanine onto lipoteichoic acid (LTA) showed increased susceptibility to Cg-BigDef1 and lysed rapidly in contact with the peptide. Cg-BigDef1 bound to S. aureus cell wall. In addition, competitive binding with exogenously added LTA was sufficient to impair Cg-BigDef1 antimicrobial activity against S. aureus. These data suggest that TAs are conserved molecular motifs recognized by Cg-BigDef1. Finally, we found that Cg-BigDef1 interaction with S. aureus was mediated by its N-terminal domain, which enables the C-terminal β-defensin-like domain to interact with the bacterial cell wall. Altogether, our results identify TAs as important targets for Cg-BigDef1. This interaction appears to be mediated by the ancestral N-terminal domain characteristic of this peptide family.

Cestodes (class Cestoda) include zoonotic parasites such as Echinococcus spp. and Taenia spp., which cause significant morbidity and mortality in endemic regions, particularly among pastoral and rural populations in low-, upper-, and middle-income countries. Their developmental plasticity reflects finely tuned regulatory mechanisms controlling gene expression throughout complex life cycles and infection stages. Despite expanding genomic resources, functional postgenomic studies remain scarce. MicroRNAs (miRNAs) are critical regulators of gene expression, influencing diverse developmental and physiological processes. Among them, miR-71-5p is highly expressed in cestodes, absent in vertebrates, and predicted to regulate essential parasite genes. Here, we employed a chemically modified antisense oligonucleotide to assess the impact of miR-71-5p knockdown during Mesocestoides vogae infection. To the best of our knowledge, this represents the first in vivo report of miRNA knockdown in a cestode infection model. Treated mice exhibited a 67% (3-fold) reduction in parasitic mass compared with controls, suggesting that miR-71-5p is essential for infection establishment and progression. Toxicity analyses in uninfected mice revealed no adverse effects. Whole-mount in situ hybridization showed broad miR-71-5p expression across tissues, including germinative cells, suggesting a pleiotropic role. These findings advance the understanding of miRNA-mediated regulation in cestodes and highlight these small RNAs as promising therapeutic targets for neglected tropical diseases (NTDs) prioritized by the World Health Organization (WHO).

Being a persistent and deadly infection, tuberculosis (TB) caused by Mycobacterium tuberculosis remains a global health challenge. Despite having a well-established 4-drug combination therapy for drug-sensitive TB, the emergence of drug-resistant TB has rendered the treatment less effective. Although fluoroquinolones (FQs) are among the prominent drugs in the second-line treatment for multidrug-resistant tuberculosis (MDR-TB), FQ resistance has readily emerged in cases of extensively drug-resistant tuberculosis (XDR-TB). Other than the mutations in DNA gyrase, a universally conserved bacterial enzyme targeted by FQs, several mechanisms contribute to the emergence of FQ resistance. Recently, post-translational modification of DNA gyrase is implicated as one of the mechanisms for FQ resistance. Here, we describe succinylation of GyrB by a promiscuous acetyltransferase, Eis of M. tuberculosis, as a new mechanism contributing to FQ resistance in mycobacteria. Lysine succinylation of GyrB results in a reduced interaction of FQs with the enzyme, thereby decreasing the DNA cleavage by DNA gyrase in the presence of FQs. Accordingly, Eis overexpressing mycobacterial strains exhibit increased minimum inhibitory concentration (MIC) to FQs. Thus, succinylation of DNA gyrase is yet another resistance mechanism against the FQs.

Bacterial and human cells produce extracellular vesicles (EVs) in response to diverse stimuli, e.g., toxins, oxidative stress, nutrient depletion, or high cell density. Here, we describe a cocultivation platform that allows recovery of mixed extracellular vesicles (mix-EVs) produced simultaneously by both cell types. We investigated interactions between Gram-positive and Gram-negative bacteria (Streptococcus pyogenes, Staphylococcus aureus, Escherichia coli, and Neisseria meningitidis) and human peripheral blood mononuclear cells (PBMCs). The production of the mix-EVs population decreased with higher bacterial concentrations. Exposing PBMCs to mix-EVs repressed the general transcriptomic signature, in contrast with a significant upregulation generated by single bacterial-EVs. However, mix-EVs-derived IL-1β upregulation was confirmed at the protein level. Inhibition experiments showed that IL-1β production involved TLR2 and TLR4 signaling, acting through IRAK-1 and TRAF6 related pathways. This approach provides a new platform for the study of EVs at the pathogen–host interface and presents mechanistic insights into the effect of EVs on an infected host.

Rapid detection of indole-3-ethanol (IEt or tryptophol), a quorum-sensing molecule that regulates Candida albicans virulence mechanisms, offers a direction for innovative antifungal discovery and infection treatments. Thus, nanostructured electrochemical sensing platforms were designed and fabricated, and their electrocatalytic properties were evaluated for tryptophol direct determination in biological samples. In this regard, various nanostructured materials were studied as individual modifiers for printed disposable biosensing chips, with the TiO₂@MWCNTs nanocomposite ultimately selected as the optimal candidate. Comprehensive assay optimization was subsequently performed by investigating key experimental parameters, including the choice of supporting electrolyte, pH, scan rate effects, and mechanistic aspects of the tryptophol redox reaction(s). Under the optimized conditions, the biosensor exhibited a wide dynamic linear range of 0.10–14.00 μg·mL^–1 and achieved a low limit of detection of 20.00 ng·mL^–1 using chronoamperometric measurements. The selectivity of the platform was further validated by challenging the biosensor with a panel of nontarget interfering molecules, none of which produced measurable electrochemical responses in the absence of the tryptophol. Importantly, the proposed assay demonstrated an excellent environmental profile, as confirmed by its high score on the Analytical Eco-Scale and favorable assessment using the Complex Green Analytical Procedure Index, underscoring its potential as a cost-effective and environmentally sustainable analytical tool.

The global rise of antibiotic-resistant pathogens has created an imperative to discover novel antimicrobial strategies. Traditional antibiotics predominantly target essential bacterial processes, such as cell division, DNA replication, transcription, and translation, but few new agents targeting these pathways have emerged in recent decades. We explored an alternative approach by identifying small molecules that hyperactivate the bacterial ClpP protease, thereby inducing uncontrolled proteolysis and ultimately leading to bacterial cell death. Leveraging the known binding interactions of the peptide antibiotic ADEP4 with ClpP, we performed high-throughput in silico screening. Molecular docking simulations prioritized compounds based on predicted binding affinity (kcal/mol), complemented by structural chemistry evaluation and in silico pharmacokinetic profiling. AGI-6780 emerged as a lead compound with high predicted affinity for the ClpP active site. In vitro assays showed that AGI-6780 effectively inhibits a panel of Gram-positive bacteria by targeting ClpP. It also exhibits synergy with the antibiotic rifampicin and has minimal cytotoxicity on human cell lines. AGI-6780 is a promising antimicrobial agent that uniquely exploits ClpP, an unconventional bacterial target.