ACS Infectious Diseases最新文献

Among the critical priority pathogens listed by the World Health Organization, Mycobacterium tuberculosis strains resistant to rifampicin present a significant global threat. Consequently, the study of the mechanisms of resistance to new antitubercular drugs and the discovery of new effective molecules are two crucial points in tuberculosis drug discovery. In this study, we discovered a compound named RCB18350, which is active against M. tuberculosis growth and exhibits a minimum inhibitory concentration (MIC) of 1.25 μg/mL. It was also effective against multidrug-resistant isolates. We deeply studied the mechanism of resistance/action of RCB18350 by using several approaches. We found that Rv3406, an iron- and α-ketoglutarate-dependent sulfate ester dioxygenase, is capable of metabolizing the compound into its inactive metabolite. This finding highlights the role of this enzyme in the mechanism of resistance to RCB18350.

Pneumonia caused by Staphylococcus aureus infection has consistently been a significant cause of morbidity and mortality worldwide. Extensive research to date indicates that N6-methyladenosine (m6A) modification plays a crucial role in the development and progression of various diseases. However, it remains unknown whether the m6A modification affects the progression of bacterial pneumonia. To explore this question, we assessed the levels of m6A as well as the expression of methyltransferases (METTL3 and METTL14), demethylase fat mass and obesity-related protein (FTO), and methylation reader proteins YTHDF1 and YTHDF2 in mice and MH-S cells during S. aureus infection. The levels of m6A and METTL3 were significantly upregulated in S. aureus-infected mice and MH-S cells. siMETTL3 knockdown resulted in more severe bacterial colonization, lung damage, increased inflammatory cytokines (IL-6, IL-1β, TNF-α), and mortality rates in mice as well as MH-S cells following the bacterial infection. Regulation of lung inflammation levels by METTL3 was associated with the activation of the MAPK/NF-κB/JAK2-STAT3 signaling pathway. Moreover, siMETTL3 mice exhibited an increased release of superoxides and exacerbated oxidative stress in the lungs following S. aureus infection, which was correlated with impaired mitochondrial autophagy mediated by the Pink1/Parkin pathway. Our findings provide previously unrecognized evidence of the protective role of METTL3 in S. aureus-induced acute pneumonia, indicating a potential therapeutic target for S. aureus infections.

Tuberculosis remains a major global health threat, with traditional antibiotic treatments facing challenges such as drug resistance. Host-directed therapy (HDT) has emerged as a promising approach to combat tuberculosis by enhancing the host immune response. CXCL14, a chemokine family member, plays a crucial role in regulating host antipathogenic immune responses. To elucidate the role of CXCL14 and its key regulatory molecules in mycobacterial infections, we identified new targets for host-directed therapy. RAW264.7 macrophages were pretreated with CXCL14 and infected with Mycobacterium smegmatis. CFU, ROS levels, and apoptosis were assessed. Cell RNA was extracted for high-throughput sequencing, and significantly differentially expressed genes were screened and identified. The effects of candidate genes were verified using knockdown and overexpression techniques. A mouse model of mycobacterial infection was established to validate the role of CXCL14 in vivo. CXCL14 pretreatment significantly reduced intracellular mycobacteria and increased ROS levels in macrophages without affecting apoptosis. Transcriptome analysis identified A20 as a key differentially expressed gene. A20 overexpression promoted ROS production and decreased intracellular mycobacteria, while A20 knockdown reversed these effects. The combination of CXCL14 and A20 overexpression effectively inhibited mycobacterial survival in macrophages. CXCL14 significantly inhibited mycobacterial survival in mice and reduced organ damage in vivo. CXCL14 promoted ROS production in macrophages by upregulating A20 expression, thereby inhibiting mycobacterial survival. In the mouse model, CXCL14 alleviated inflammatory responses and histopathological damage caused by mycobacterial infection. These findings suggest that CXCL14 is a promising new HDT molecule for the treatment of mycobacterial infections.

Antimicrobial resistance (AMR) poses a major threat to human health globally. Approximately 5 million deaths were attributed to AMR in 2019, and this figure is predicted to worsen, reaching 10 million deaths by 2050. In the search for new compounds that can tackle AMR, FtsZ inhibitors represent a valuable option. In the present study, a structure-based virtual screening is reported, which led to the identification of derivative C11 endowed with an excellent minimum inhibitory concentration value of 2 μg/mL against Staphylococcus aureus. Biochemical assays clarified that compound C11 targets FtsZ by inhibiting its polymerization process. C11 also showed notable antimicrobial activity against S. aureus cystic fibrosis isolates and methicillin-resistant S. aureus strains. Derivative C11 did not show cytotoxicity, while it had a synergistic effect with methicillin. C11 also showed increased survival in the Galleria mellonella infection model. Lastly, structure-activity relationship and binding mode analyses were reported.

Acinetobacter baumannii (AB) is an opportunistic pathogen with growing clinical relevance due to its increasing level of antimicrobial resistance in the last few decades. In the event of an AB hospital outbreak, fast detection and localization of the pathogen is crucial, to prevent its further spread. However, contemporary diagnostic tools do not always meet the requirements for rapid and accurate diagnosis. For this reason, we report here the possibility of using gallium-68 labeled siderophores, bacterial iron chelators, for positron emission tomography imaging of AB infections. In our study, we radiolabeled several siderophores and tested their in vitro uptake in AB cultures. Based on the results and the in vitro properties of studied siderophores, we selected two of them for further in vivo testing in infectious models. Both selected siderophores, ferrioxamine E and ferrirubin, showed promising in vitro characteristics. In vivo, we observed rapid pharmacokinetics and no excessive accumulation in organs other than the excretory organs in normal mice. We demonstrated that the radiolabeled siderophores accumulate in AB-infected tissue in three animal models: a murine model of myositis, a murine model of dorsal wound infection and a rat model of pneumonia. These results suggest that both siderophores radiolabeled with Ga-68 could be used for PET imaging of AB infection.

Over 1370 class D β-lactamases are currently known, and they pose a serious threat to the effective treatment of many infectious diseases, particularly in some pathogenic bacteria where evolving carbapenemase activity has been reported. Detailed understanding of their molecular biology, enzymology, and structural biology are critically important, but the lack of a standardized residue numbering scheme and inconsistent secondary structure annotation has made comparative analyses sometimes difficult and cumbersome. Compounding this, in the post-AlphaFold world where we currently find ourselves, an extraordinary wealth of detailed structural information on these enzymes is literally at our fingertips; therefore it is vitally important that a standard numbering system is in place to facilitate the accurate and straightforward analysis of their structures. Here we present a residue numbering and secondary structure scheme for the class D enzymes based on the sequence and structure of OXA-48 and apply it to test targets to demonstrate the ease with which it can be used.

G-quadruplexes (GQs) have been primarily studied in the context of cancer and neurodegenerative pathologies. However, recent research has shifted focus to their existence and functional roles in viral genomes, revealing GQ-regulated key pathways in various human pathogenic viruses. While GQ structures have been reported in the genomes of emerging and re-emerging viruses, RNA viruses have been understudied compared to DNA viruses, including notable examples such as human immunodeficiency virus-1, hepatitis C virus, Ebola virus, Nipah virus, Zika virus, and SARS-CoV-2. The flavivirus family, comprising the Japanese encephalitis virus (JEV), poses a significant global threat due to recurring outbreaks yet lacks approved antivirals. In this study, we identified and characterized eight putative G-quadruplex-forming motifs within essential genes involved in genome replication, assembly, and internalization in the host cell, conserved across different JEV isolates. The formation and stability of these motifs were validated through a multitude of biophysical and cell-based assays. The interaction and binding affinity of these motifs with the known GQ-binding ligand BRACO-19 were supported by biophysical assays, confirming the capability of these motifs to form GQ structures. Notably, BRACO-19 also exerted antiviral properties through reduction of viral replication and infectious virus titers as well as inhibition of viral protein expression, as evaluated by the cell-based assays. This comprehensive molecular characterization of G-quadruplex structures within the JEV genome highlights their potential as promising antiviral targets for intervention strategies against JEV infection through GQ-specific ligands.

Although not currently in the infectious disease spotlight, there is still a pressing need for new agents to treat tuberculosis caused by Mycobacterium tuberculosis. As there is an ever-increasing amount of clinical resistance to the current drugs, ideally new drugs would be found against novel targets to circumvent pre-existing resistance. A phenotypic growth screen identified a novel singleton, 1, as an inhibitor of M. tuberculosis growth. Mechanism-of-action studies determined that 1 targeted Pks13, an essential enzyme in cell wall biosynthesis that, as of yet, has not been targeted by agents in the clinic. The reactive nature of the pentafluorophenyl warhead meant that the molecule was inherently metabolically unstable. A medicinal chemistry optimization program is described that resulted in the identification of a compound that was reactive enough to still inhibit Pks13 and M. tuberculosis growth while being metabolically stable enough to explore in vivo.

Tuberculosis (TB) is the leading cause of death from infectious disease. Macrophages are the primary immune responders and become the primary host cells for the causative agent Mycobacterium tuberculosis. Following the uptake of M. tuberculosis, the inherent antimicrobial action of macrophages is dampened, enabling the bacterium to reside within these cells and multiply. Rising resistance of M. tuberculosis to antibiotics has led to the investigation of novel approaches for the treatment of TB. Here, we report a host-directed approach, employing biomimetic Curdlan poly(lactic-co-glycolic acid) (C-PLGA) nanoparticles (NPs), and examine autophagy induction in infected macrophages, eradication of M. tuberculosis and immune modulation in a mouse model. We demonstrate that the NPs induce autophagy in M. tuberculosis-infected macrophages. Treatment of H37Rv infected C57BL/6 mice with these NPs reduced M. tuberculosis burden in the lungs of mice and modulated cytokines and chemokines and this work demonstrates that these immunomodulatory NPs are a potential treatment approach for TB.

The antimicrobial resistance (AMR) crisis has been associated with millions of deaths. Of particular concern is the threat of bioweapons, exemplified by anthrax. Introduction of novel antibiotics helps mitigate AMR, but does not address the threat of bioweapons with engineered resistance. We reasoned that teixobactin, an antibiotic with no detectable resistance, is uniquely suited to address the challenge of weaponized anthrax. Teixobactin binds to immutable targets, precursors of cell wall polymers. Here we show that teixobactin is highly efficacious in a rabbit model of inhalation anthrax. Inhaling spores of Bacillus anthracis causes overwhelming morbidity and mortality. Treating rabbits with teixobactin after the onset of disease rapidly eliminates the pathogen from blood and tissues, normalizes body temperature, and prevents tissue damage. Teixobactin assembles into an irreversible supramolecular structure on the surface of B. anthracis membrane, likely contributing to its unusually high potency against anthrax. Antibiotics evading resistance provide a rational solution to both AMR and engineered bioweapons.