ACS Infectious Diseases最新文献

Mycobacterium tuberculosis (Mtb)is responsible for more deaths per year than any other infectiousdisease. Resistance of circulating Mtb to the standard of care treatmentregimen is an urgent global health crisis for which novel antibiotictreatments are needed. We have developed extremely potent, orallybioavailable, small-molecule inhibitors of inosine 5′-monophosphatedehydrogenase (GuaB) that catalyze the rate-limiting step in de novo guanine biosynthesis. The inhibitors exhibited bactericidalactivity against Mtb in extracellular, intracellular, and hypoxicenvironments that capture features of advanced disease pathology inpatients. Mtb GuaB2 inhibitors (GuaBi) were efficacious in three different in vivo mouse models of Mtb lung infection: the C57BL/6super acute, C57BL/6 chronic, and C3HeB/FeJ (Kramnik) models. In thechronic BALB/c infection model of primarily intracellular Mtb, nobenefit was observed, whereas in the C3HeB/FeJ model, a bedaquiline,pretomanid, and moxifloxacin treatment regimen that included GuaBiled to a rapid elimination of culturable Mtb infection in half ofthe mice. Notably, the C3HeB/FeJ model recapitulates advanced pathophysiologyand heterogeneous disease that includes caseous necrotic granulomas,intracellular and extracellular reservoirs of Mtb, and lethal progressiveinfection. These results support further evaluation of a GuaBi-containingtherapeutic regimen in relapse-capable preclinical models.

The Pseudomonas aeruginosa typeIII secretion system effector ExoU is a potent phospholipase A2 thatcauses rapid host-cell injury, but how it engages intracellular hostnetworks during infection remains incompletely understood. Here, usingan endogenously Flag-tagged infection model in male-derived A549 cells,we identified MYH6 and DDX3Y as ExoU-associated host factors. Knockdownof either protein reduced PA14-induced cytotoxicity, indicating thatboth contribute to the cellular response to ExoU-positive P. aeruginosa. An in vitro pull-down assay usingpurified proteins further supported a direct but relatively weak associationbetween ExoU-S142A and DDX3Y. Quantitative phosphoproteomic analysisrevealed extensive host phosphorylation changes associated with ExoUcatalytic activity and identified multiple phosphorylation sites onDDX3Y. Phosphorylation at S506 was detected following PA14 infectionbut not following exoU-S142A infection. Phospho-deficientDDX3Y mutants at S101, S141, and S506 showed increased associationwith ExoU, whereas the combined S101A/S141A/S506A mutant further enhancedthis association and reduced infection-induced cytotoxicity. Conversely,the phosphomimetic S506E mutant showed reduced association with ExoUand restored cytotoxicity relative to S506A. RNA sequencing and DDX3YRIP analyses further showed that ExoU catalytic activity was associatedwith a broader inflammatory transcriptional response and with changesin the DDX3Y-bound transcriptome, including altered association with IL6ST and NFKBIZ transcripts. Together,these findings identify MYH6 and DDX3Y as distinct ExoU-associatedhost factors and support a model in which ExoU catalytic activityis linked to multisite regulation of DDX3Y, altered ExoU-DDX3Y association,and changes in DDX3Y-associated RNAs. These results extend the currentunderstanding of ExoU-mediated cytotoxicity beyond direct membranedamage.

Antibiotic resistance in Gram-negative bacteria is amajor globalhealth threat, in part because of the permeability barriers of theirdouble-membrane envelope and active efflux systems. While porins,lipopolysaccharides, and efflux pumps have been extensively studied,the role of membrane energetics, particularly the Donnan potential(DP), in antibiotic susceptibility remains poorly understood. TheDP arises from negatively charged osmoregulated periplasmic glucans(OPGs), which generate an electrostatic potential in the periplasmthat is capable of influencing how molecules traverse the outer membrane.Here, we systematically examine how OPG-dependent electrostatic changesassociated with the DP shape antibiotic susceptibility in Escherichia coli. By altering the environmental osmolarity,we generated conditions that changed OPG abundance and were expectedto alter associated periplasmic electrostatics, revealing that low-saltconditions enhance the potency of cationic antibiotics but reducethe activity of anionic compounds, whereas high-salt conditions orOPG deficiency attenuate cationic drug activity. Strains producingneutral OPGs phenocopied OPG-deficient mutants, implying that theOPG charge is involved in this effect. Clinical E. coli isolates varied in sensitivity to osmolarity-and OPG-dependent electrostatic effects, and similar trends were observedacross multiple Gram-negative pathogens. Finally, we show that dietarysalt intake modulates antibiotic efficacy in vivo in a manner consistent with the salt-dependent susceptibility observed in vitro. Together, these findings systematically quantifyantibiotic susceptibility phenotypes across a broad compound paneland under environmental and genetic perturbations expected to alterOPG-associated periplasmic electrostatics and suggest new principlesfor antibiotic design and therapeutic optimization against multidrug-resistantpathogens.

Chagas disease, caused by Trypanosoma cruzi, remains a neglected tropical disease with limited therapeutic options. Although benznidazole and nifurtimox are the available antiparasitic treatments, assessing treatment efficacy in adults with chronic Chagas disease remains challenging due to the absence of validated biomarkers or surrogate end points. Conventional serology assays often require years to decades to detect treatment-associated changes, limiting their utility in clinical trials and drug development. Biomarker development is further complicated by intermittent parasitemia, persistent antibody responses, the lack of direct measures of tissue parasite clearance, and limited longitudinal biorepositories for validation. This position paper critically evaluates biomarkers, including nonconventional serological markers such as T. cruzi 29 kDa flagellar calcium-binding protein (F29), glycosylphosphatidylinositol-anchored trypomastigote (tGPI)-mucins, and alpha-galactosyl (α-Gal) epitope; molecular approaches; and multiplex serological platforms such as MultiCruzi. Their potential utility, supporting evidence, methodological limitations, reproducibility, and validation status are assessed within a fit-for-purpose scientific and regulatory framework. Although several biomarkers have shown promise in detecting early treatment-associated biological signals, none currently has sufficient evidence to qualify as a validated surrogate end point in adult chronic Chagas disease. Early biomarker changes should therefore be interpreted as indicators of treatment-associated biological activity rather than direct evidence of parasitological cure or a durable clinical benefit. Beyond summarizing the biomarker landscape, this paper addresses the evidentiary and regulatory challenges associated with biomarker qualification and proposes a roadmap for future qualification efforts. Progress will require standardized methodologies, independent prospective validation, longer term follow-up, and robust evidence, demonstrating that biomarker changes reliably predict clinically meaningful outcomes.

Tick-borne encephalitis (TBE) is an escalating globalhealth threat,increasingly exacerbated by climate change, and underscores the needfor innovative vaccine strategies. Conventional subunit vaccines arelimited by suboptimal spatiotemporal dissociation between antigensand adjuvants, as well as insufficient specific targeting, resultingin compromised immunogenicity. Herein, we report a biomimetic nanovaccineplatform engineered to overcome these limitations through the synergisticco-delivery of antigen and adjuvant. This platform is constructedby co-displaying the TBE virus envelope protein domain III (fusedto a dendritic cell-targeting peptide, Dcpep) together with the molecularadjuvant MAB2560 on the surface of bacterium-like particles (BLPs).The resulting co-display vaccine, EDc2&MAB2560-GEM BLPs, outperformsa simple mixture of its components, inducing significantly highertiters of TBEV-specific IgG antibodies, robust T-cell and B-cell immuneresponses, and durable immunity in mice. Mechanistic studies revealthat these enhanced immune responses arise from the platform’sability to precisely co-deliver antigen and adjuvant to dendriticcells, thereby triggering a potent cascading immunostimulatory effect.This work highlights the critical role of spatiotemporal couplingwithin targeted nanocarriers and establishes a versatile strategyfor the development of next-generation subunit vaccines with enhancedpotency and safety.

Human milk oligosaccharides(HMOs) are bioactive carbohydratesthat govern host–microbe interactions and immune regulation.Beyond their antimicrobial and antibiofilm functions, HMOs have beenshown to modulate inflammatory pathways by altering cytokine expression,including interleukin-1β (IL-1β) and tumor necrosis factor-α(TNF-α), which are key mediators in infection and inflammationassociated complications. In this study, we characterize the effectsof HMOs on cytokine secretion in THP-1 macrophages stimulated with lipopolysaccharides using a validated magnetic beadelectrochemical sandwich assay (MBESA). The electrochemical assayenabled precise quantification of cytokine responses and revealedthat HMO treatment attenuated proinflammatory signaling in LPS stimulatedmacrophages. These findings provide new insights into the immunomodulatoryproperties of HMOs and demonstrate the utility of electrochemicalbiosensing platforms for rapid, sensitive assessment of cellular inflammatoryresponses. Future studies will expand this approach to microphysiologicalsystems to further elucidate HMO mediated regulation of immune signaling.

Currenttreatment options for multidrug-resistant (MDR) Gram-negativeinfections are effectively limited to last-resort antibiotics, suchas the polymyxins. Clinical use of polymyxins remains limited dueto significant nephrotoxic side effects, and is further limited asa result of increasing polymyxin resistance. The novel polymyxin antibiotic,SPR206, developed in 2019, retains potency against polymyxin-susceptibleGram-negative bacteria while showing no adverse side effects in Phase1 clinical trials. However, resistance to SPR206 is anticipated throughthe same mechanisms that drive resistance to the currently availablepolymyxins. We have reported several small-molecule polymyxin adjuvantscaffolds that reverse resistance in polymyxin-resistant Gram-negativebacteria. Herein, we describe the evaluation of six previously reportedcolistin adjuvants for the modulation of SPR206 activity in polymyxin-resistant Acinetobacter baumannii and Klebsiella pneumoniae. Several adjuvants exhibit equipotent orincreased activity with SPR206 compared to that with colistin, andmaintain SPR206 adjuvant activity against a panel of clinical isolates.Additionally, bacteria do not evolve resistance to the combinationof adjuvant NDM-27 and SPR206 over a seven-day period,with low spontaneous mutation frequencies of 4.54 × 10^–8 (AB4106) and 3.32 × 10^–9 (KPB9) at 4X theSPR206 minimum inhibitory concentration. Overall, these data supportthe potential use of previously developed adjuvants to augment theactivity of next-generation polymyxins.

Carbapenem-resistant Enterobacterales (CRE), including Escherichia coli and Klebsiella pneumoniae are increasingly common pathogens. Resistance in CRE is often associatedwith production of K. pneumoniae (KPC)carbapenemases. We report a structurally modified meropenem derivative,JDB-1-200 (i.e., 8-epi-meropenem, in which the stereochemistry ofthe C8 hydroxyl is inverted), displaying enhanced activity relativeto meropenem against KPC-producing CRE. JDB-1-200 alone displayedsuperior activity (MICs of 0.5 to 1 mg/L, compared with >8 mg/Lformeropenem) against several clinically relevant Enterobacterales, includingKPC-producing K. pneumoniae and Citrobacter freundii. Crystallographic analysis ofJDB-1-200 complexes with the E166Q deacylation-deficient KPC-2 mutant,compared with an analogous meropenem (8R-hydroxyl)complex, indicates that the improvement arises from the JDB 8S-hydroxyl group acting as a hydrogen-bond donor to thehydrolytic water, slowing acyl-enzyme hydrolysis, with similar interactionsobserved in a CTX-M-15:JDB-1-200 complex. Kinetic inhibition datafor KPC-2 and CTX-M-15 indicate that JDB-1-200 could be used aloneor alongside a β-lactamase inhibitor for effective CRE treatment.

The accessory generegulator (agr) quorum-sensingsystem in Staphylococcus aureus playsa prominent role in acute infections caused by this common pathogen.In contrast, ATP synthase affects the ability of S. aureus to establish chronic infections and persistas small colony variants. In this study, we report that a syntheticsmall molecule, CP-20, is capable of dually inhibiting agr and ATP synthase. We demonstrate CP-20’s ability to counteractkey virulence phenotypes associated with both pathways, includinghemolysis, biofilm formation, and antibiotic resistance. We also showthat CP-20 facilitates more efficient clearance of S. aureus by murine macrophages than genetic inactivationof either agr or ATP synthase alone, suggesting thatdual inhibition may have an additive effect on ablating intracellularsurvival. This work demonstrates the utility of a single chemicalmodulator to attenuate S. aureus pathogenesisvia two nonessential pathways and suggests a pathway toward nonbactericidalvirulence control.

Cardiovascular implant infectionssignificantly impact morbidityand mortality. Bacteriophage therapy has emerged as a potential strategyfor device-related infection, particularly in biofilm-associated settingswhere conventional antimicrobial therapy is limited, often necessitatingdevice removal. This review outlines phage treatment principles, includingbiofilm invasion, phage-antibiotic interaction, phage resistance,and infection protection mechanisms. We explore innovative approachesfor using bacteriophages to treat infections around prosthetic vasculargrafts, heart valves, left ventricular assist devices, and cardiacimplantable electronic devices. Key issues in using bacteriophagesfor cardiovascular device infections include phage selection, resistancedetection, phage production, regulatory aspects, and experimentalmodels considering infection and device flow dynamics. Although clinicaltrials on phage therapy effectiveness are unavailable, its promiseis significant.