ACS Infectious Diseases最新文献

The complete tricarboxylic acid (TCA) cycle, comprising a series of 8 oxidative reactions, occurs in most eukaryotes in the mitochondria and in many prokaryotes. The net outcome of these 8 chemical reactions is the release of the reduced electron carriers NADH and FADH₂, water, and carbon dioxide. The parasites of the Plasmodium spp., belonging to the phylum Apicomplexa, have all the genes for a complete TCA cycle. The parasite completes its life cycle across two hosts, the insect vector mosquito and a range of vertebrate hosts including humans. As the niches that the parasite invades and occupies in the two hosts vary dramatically in their biochemical nature and availability of nutrients, the parasite's energy metabolism has been accordingly adapted to its host environment. One such pathway that shows extensive metabolic plasticity in parasites of the Plasmodium spp. is the TCA cycle. Recent studies using isotope-tracing targeted-metabolomics have highlighted conserved and parasite-specific features in the TCA cycle. This Review provides a comprehensive summary of what is known of this central pathway in the Plasmodium spp.

Developing new classes of drugs that are active against infections caused by Mycobacterium tuberculosis is a priority for treating and managing this deadly disease. Here, we describe screening a small library of 20 DNA gyrase inhibitors and identifying new lead compounds. Three structurally diverse analogues were identified with minimal inhibitory concentrations of 0.125 μg/mL against both drug-susceptible and drug-resistant strains of M. tuberculosis. These lead compounds also demonstrated antitubercular activity in ex vivo studies using infected THP-1 macrophages with minimal cytotoxicity in THP-1, HeLa, and HepG2 cells (IC₅₀ ≥ 128 μg/mL). The molecular target of the lead compounds was validated through biochemical studies of select analogues with purified M. tuberculosis gyrase and the generation of resistant mutants. The lead compounds were assessed in combination with bedaquiline and pretomanid to determine the clinical potential, and the select lead (158) demonstrated in vivo efficacy in an acute model of TB infection in mice, reducing the lung bacterial burden by approximately 3 log₁₀ versus untreated control mice. The advancement of DNA gyrase inhibitors expands the field of innovative therapies for tuberculosis and may offer an alternative to fluoroquinolones in future therapeutic regimens.

Pseudomonas aeruginosa is the predominant bacterium found in many chronic biofilm infections. Over the past few decades, biofilm-related infections have posed a significant challenge to medical practice due to the increasing emergence of multidrug resistance. Cis-2-decenoic acid (CDA), a small molecule found in P. aeruginosa, has been shown to disperse biofilms formed by various bacteria and to work in synergy with common antibiotics. Despite that, the binding mechanism between CDA and the predicted cyclases/histidine kinases associated sensory extracellular (CHASE) domain of sensor protein DspS remains unknown in the absence of a crystallized protein structure. Moreover, the therapeutic potential of CDA is limited by its susceptibility to oxidative degradation and isomerization. In this work, we propose a structural model for the DspS CHASE domain. The resulting model displays an overall topology reminiscent of the sensor protein PcrK in Xanthomonas campestris. Through molecular dynamics simulations, a stable potential binding site for CDA was further identified. Virtual screening against the predicted site of DspS CHASE using our developed pipeline discovered two promising compounds, compounds 2 and 9, capable of dislodging 7-day P. aeruginosa biofilms at 50 μM without affecting bacterial growth. These compounds also enhanced the effects of ciprofloxacin against P. aeruginosa, reduced the survival of dispersed cells, and increased the expression of matrix-degrading enzyme genes pelA, pslG, and eddA. This study provides insights into CDA recognition by DspS and represents the first large-scale effort to uncover first-in-class DspS activators. At the same time, this work also underscores the effectiveness of a computational-aided drug discovery process in finding new activators, even without a known protein structure.

Group B Streptococcus (GBS) is a major cause of fetal and neonatal mortality worldwide. Many of the adverse effects of invasive GBS are associated with inflammation; therefore, understanding bacterial factors that promote inflammation is of critical importance. Membrane vesicles (MVs), which are produced by many bacteria, may modulate host inflammatory responses. While it is known that mice injected intra-amniotically with GBS MVs exhibit large-scale leukocyte infiltration, preterm birth, and subsequent fetal death, the immune effectors driving this response remain unclear. Here, we hypothesized that THP-1 macrophage-like cells respond to GBS-derived MVs by producing proinflammatory cytokines and are recognized through one or more pattern recognition receptors. We show that THP-1s produce high levels of neutrophil- and monocyte-specific chemokines in response to MVs derived from different clinical isolates of GBS. Using antibody microarrays and multiplex Luminex assays, we found that GBS MVs elicit significantly (p < 0.05) higher levels of CCL1, CCL2, CCL20, CXCL1, CXCL10, and IL-1β relative to untreated THP-1s. Using chemical inhibitors in combination with caspase-1 activity assays and Luminex assays, we further demonstrate that GBS MVs upregulated IL-1β production in a caspase-1 and NLRP3-dependent manner, ultimately identifying NLRP3 as a sensor of GBS MVs. These data indicate that MVs contain one or more pathogen-associated molecular patterns that can be sensed by the immune system and show that the NLRP3 inflammasome is a novel sensor of GBS MVs. Our data additionally indicate that MVs may serve as immune effectors that can be targeted for immunotherapeutics.

Antibiotics that operate via multiple mechanisms of action are a promising strategy to combat growing resistance. Previous studies have shown that dual action antifolates formed from a pyrroloquinazolinediamine core can inhibit the growth of bacterial pathogens without developing resistance. In this work, we expand the scope of dual action antifolates by repurposing the 2,4-diamino-1,6-dihydro-1,3,5-triazine (DADHT) cycloguanil scaffold to a variety of derivatives designed to inhibit dihydrofolate reductase (DHFR) and disrupt bacterial membranes. Dual mechanism DADHTs have activity against a variety of target pathogens, including Mycobacterium tuberculosis, Mycobacterium abscessus, and Pseudomonas aeruginosa, among other ESKAPEE organisms. Through X-ray crystallography, we confirmed engagement of the Escherichia coli DHFR target and found that some DADHTs stabilize a previously unobserved conformation of the enzyme but, broadly, bind in the occluded conformation. Using in vitro inhibition of purified E. coli and Staphylococcus aureus DHFR and disruption of E. coli membranes, we determined that alkyl substitution of dihydrotriazine at the 6-position best optimizes the DADHT’s two mechanisms of action. By employing both mechanisms, the DADHT spectrum of activity was extended beyond the scope of traditional antifolates. We are optimistic that the dual mechanism approach, particularly through the action of antifolates, offers a unique means of combating hard-to-treat bacterial infections.

Multidrug-resistant bacteria (MDR) have become a global threat, impairing positive outcomes in many cases of infectious diseases. Treating bacterial infections with antibiotic monotherapy has become a huge challenge in modern medicine. Although conventional antibiotics can be efficient against many bacteria, there is still a need to develop antimicrobial agents that act against MDR bacteria. Bioactive peptides, particularly effective against specific types of bacteria, are recognized for their selective and effective action against microorganisms and, at the same time, are relatively safe and well tolerated. Therefore, a growing number of works have proposed the use of antimicrobial peptides (AMPs) in synergism with commercial antibiotics as an alternative therapeutic strategy. This review provides an overview of the critical parameters for using AMPs in synergism with antibiotics as well as addressing the strengths and weaknesses of this combination therapy using in vitro and in vivo models of infection. We also cover the challenges and perspectives of using this approach for clinical practice and the advantages of applying artificial intelligence strategies to predict the most promising combination therapies between AMPs and antibiotics.

Vector-borne diseases are caused by microbes transmitted to humans through vectors such as mosquitoes, ticks, flies, and other arthropods. Three vector-borne diseases, filariasis, leishmaniasis, and malaria, are significant parasitic diseases which are responsible for long-term morbidity and mortality affecting millions globally. These diseases exhibit several similarities in transmission, health impacts, and the challenges faced in their control and prevention. By identifying these commonalities and fostering cooperation among disease control programs, we can strengthen our efforts to combat them and hence enhance the health of at-risk populations. This review summarizes the key points associated with the epidemiology, transmission dynamics, and therapeutic regimes for each disease, presenting a holistic overview of these three eliminable diseases.

Half the world's population is at risk of developing a malaria infection, which is caused by parasites of the genus Plasmodium. Currently, resistance has been identified to all clinically available antimalarials, highlighting an urgent need to develop novel compounds and better understand common mechanisms of resistance. We previously identified a novel tetrahydro-β-carboline compound, PRC1590, which potently kills the malaria parasite. To better understand its mechanism of action, we selected for and characterized resistance to PRC1590 in Plasmodium falciparum. Through in vitro selection of resistance to PRC1590, we have identified that a single-nucleotide polymorphism on the parasite's multidrug resistance protein 1 (PfMDR1 G293V) mediates resistance to PRC1590. This mutation results in stereospecific resistance and sensitizes parasites to other antimalarials, such as mefloquine, quinine, and MMV019017. Intraerythrocytic asexual stage specificity assays have revealed that PRC1590 is most potent during the trophozoite stage when the parasite forms a single digestive vacuole (DV) and actively digests hemoglobin. Moreover, fluorescence microscopy revealed that PRC1590 disrupts the function of the DV, indicating a potential molecular target associated with this organelle. Our findings mark a significant step in understanding the mechanism of resistance and the mode of action of this emerging class of antimalarials. In addition, our results suggest a potential link between resistance mediated by PfMDR1 and PRC1590's molecular target. This research underscores the pressing need for future research aimed at investigating the intricate relationship between a compound's chemical scaffold, molecular target, and resistance mutations associated with PfMDR1.

Heterogeneity during Mycobacterium tuberculosis (Mtb) infection greatly impacts disease outcome and complicates treatment. This heterogeneity encompasses many facets, spanning local differences in the host immune response to Mtb and the environment experienced by the bacterium, to nonuniformity in Mtb replication state. All of these facets are interlinked and each can affect Mtb susceptibility to antibiotic treatment. In-depth spatiotemporal understanding of Mtb-host interactions is thus critical to both fundamental comprehension of Mtb infection biology and for the development of effective therapeutic regimens. Such spatiotemporal understanding dictates the need for analysis at the single bacterium/cell level in the context of intact tissue architecture, which has been a significant technical challenge. Excitingly, innovations in spatial single cell methodology have opened the door to such studies, beginning to illuminate aspects ranging from intergranuloma differences in cellular composition and phenotype, to sublocation differences in Mtb physiology and replication state. In this perspective, we discuss recent studies that demonstrate the potential of these methodological advancements to reveal critical spatiotemporal insight into Mtb-host interactions, and highlight future avenues of research made possible by these advances.