ACS Infectious Diseases最新文献

The discovery of safe and efficient inhibitors against efflux pumps as well as metallo-β-lactamases (MBL) is one of the main challenges in the development of multidrug-resistant (MDR) reversal agents which can be utilized in the treatment of carbapenem-resistant Gram-negative bacteria. In this study, we have identified that introduction of an ethylene-linked sterically demanding group at the 3-OH position of the previously reported MDR reversal agent di-F-Q endows the resulting compounds with hereto unknown multitarget inhibitory activity against both efflux pumps and broad-spectrum β-lactamases including difficult-to-inhibit MBLs. A molecular docking study of the multitarget inhibitors against efflux pump, as well as various classes of β-lactamases, revealed that the 3-O-alkyl substituents occupy the novel binding sites in efflux pumps as well as carbapenemases. Not surprisingly, the multitarget inhibitors rescued the antibiotic activity of a carbapenem antibiotic, meropenem (MEM), in NDM-1 (New Delhi Metallo-β-lactamase-1)-producing carbapenem-resistant Enterobacteriaceae (CRE), and they reduced MICs of MEM more than four-fold (synergistic effect) in 8–9 out of 14 clinical strains. The antibiotic-potentiating activity of the multitarget inhibitors was also demonstrated in CRE-infected mouse model. Taken together, these results suggest that combining inhibitory activity against two critical targets in MDR Gram-negative bacteria, efflux pumps, and β-lactamases, in one molecule is possible, and the multitarget inhibitors may provide new avenues for the discovery of safe and efficient MDR reversal agents.

The recent COVID-19 pandemic underscored the limitations of currently available direct-acting antiviral treatments against acute respiratory RNA-viral infections and stimulated major research initiatives targeting anticoronavirus agents. Two novel nsp5 protease (MPro) inhibitors have been approved, nirmatrelvir and ensitrelvir, along with two existing nucleos(t)ide analogues repurposed as nsp12 polymerase inhibitors, remdesivir and molnupiravir, but a need still exists for therapies with improved potency and systemic exposure with oral dosing, better metabolic stability, and reduced resistance and toxicity risks. Herein, we summarize our research toward identifying nsp12 inhibitors that led to nucleoside analogues 10e and 10n, which showed favorable pan-coronavirus activity in cell-infection screens, were metabolized to active triphosphate nucleotides in cell-incubation studies, and demonstrated target (nsp12) engagement in biochemical assays.

Reverse analogs of the phosphonohydroxamic acid antibiotic fosmidomycin are potent inhibitors of the nonmevalonate isoprenoid biosynthesis enzyme 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR, IspC) of Plasmodium falciparum. Some novel analogs with large phenylalkyl substituents at the hydroxamic acid nitrogen exhibit nanomolar PfDXR inhibition and potent in vitro growth inhibition of P. falciparum parasites coupled with good parasite selectivity. X-ray crystallographic studies demonstrated that the N-phenylpropyl substituent of the newly developed lead compound 13e is accommodated in a subpocket within the DXR catalytic domain but does not reach the NADPH binding pocket of the N-terminal domain. As shown for reverse carba and thia analogs, PfDXR selectively binds the S-enantiomer of the new lead compound. In addition, some representatives of the novel inhibitor subclass are nanomolar Escherichia coli DXR inhibitors, whereas the inhibition of Mycobacterium tuberculosis DXR is considerably weaker.

Chagas disease, caused by Trypanosoma cruzi, stands as the primary cause of dilated cardiomyopathy in the Americas. Macrophages play a crucial role in the heart’s response to infection. Given their functional and phenotypic adaptability, manipulating specific macrophage subsets could be vital in aiding essential cardiovascular functions including tissue repair and defense against infection. PPARα are ligand-dependent transcription factors involved in lipid metabolism and inflammation regulation. However, the role of fenofibrate, a PPARα ligand, in the activation profile of cardiac macrophages as well as its effect on the early inflammatory and fibrotic response in the heart remains unexplored. The present study demonstrates that fenofibrate significantly reduces not only the serum activity of tissue damage biomarker enzymes (LDH and GOT) but also the circulating proportions of pro-inflammatory monocytes (CD11b⁺ LY6C^high). Furthermore, both CD11b⁺ Ly6C^low F4/80^high macrophages (MΦ) and recently differentiated CD11b⁺ Ly6C^high F4/80^high monocyte-derived macrophages (MdMΦ) shift toward a resolving phenotype (CD206^high) in the hearts of fenofibrate-treated mice. This shift correlates with a reduction in fibrosis, inflammation, and restoration of ventricular function in the early stages of Chagas disease. These findings encourage the repositioning of fenofibrate as a potential ancillary immunotherapy adjunct to antiparasitic drugs, addressing inflammation to mitigate Chagas disease symptoms.

Gram-positive bacteria, in particular Staphylococcus aureus (S. aureus), are the leading bacterial cause of death in high-income countries and can cause invasive infections at various body sites. These infections are associated with prolonged hospital stays, a large economic burden, considerable treatment failure, and high mortality rates. So far, there is only limited knowledge about the specific locations where S. aureus resides in the human body during various infections. Hence, the visualization of S. aureus holds significant importance in microbiological research. Herein, we report the development and validation of a far-red fluorescent probe to detect Gram-positive bacteria, with a focus on staphylococci, in human biopsies from deep-seated infections. This probe displays strong fluorescence and low background in human tissues, outperforming current tools for S. aureus detection. Several applications are demonstrated, including fixed- and live-cell imaging, flow cytometry, and super-resolution bacterial imaging.

Cilagicin is a dual polyprenyl phosphate binding lipodepsipeptide antibiotic with strong activity against clinically relevant Gram-positive pathogens while evading antibiotic resistance. Cilagicin showed high serum binding that reduced its in vivo efficacy. Cilagicin-BP, which contains a biphenyl moiety in place of the N-terminal myristic acid found on cilagicin, showed reduced serum binding and increased in vivo efficacy but decreased potency against some pathogens. Here, we manipulated the acyl tail and the peptide core of cilagicin to identify an optimized collection of structural features that maintain potent antibiotic activity against a wide range of pathogens in the presence of serum. This led to the identification of the optimized antibiotic dodecacilagicin, which contains an N-terminal dodecanoic acid. Dodecacilagicin exhibits low MICs against clinically relevant pathogens in the presence of serum, retains polyprenyl phosphate binding, and evades resistance development even after long-term antibiotic exposure, making dodecacilagicin an appealing candidate for further therapeutic development.

Tyrosine cross-linking has recently been used to produce nanoclusters (NCs) from peptides to enhance their immunogenicity. In this study, NCs were generated using the ectodomain of the ion channel Matrix 2 (M2e) protein, a conserved influenza surface antigen. The NCs were administered via intranasal (IN) or intramuscular (IM) routes in a mouse model in a prime-boost regimen in the presence of the adjuvant CpG. After boost, a significant increase in anti-M2e IgG and its subtypes was observed in the serum and lungs of mice vaccinated through the IM and IN routes; however, significant enhancement in anti-M2e IgA in lungs was observed only in the IN group. Analysis of cytokine concentrations in stimulated splenocyte cultures indicated a Th1/Th17-biased response. Mice were challenged with a lethal dose of A/California/07/2009 (H1N1pdm), A/Puerto Rico/08/1934 (H1N1), or A/Hong Kong/08/1968 (H3N2) strains. Mice that received M2e NCs + CpG were significantly protected against these strains and showed decreased lung viral titers compared with the naive mice and M2e NC-alone groups. The IN-vaccinated group showed superior protection against the H3N2 strain as compared to the IM group. This research extends our earlier efforts involving the tyrosine-based cross-linking method and highlights the potential of this technology in enhancing the immunogenicity of short peptide immunogens.

Peptidoglycan synthesis is an underutilized drug target in Mycobacterium tuberculosis (Mtb). Diazabicyclooctanes (DBOs) are a class of broad-spectrum β-lactamase inhibitors that also inhibit certain peptidoglycan transpeptidases that are important in mycobacterial cell wall synthesis. We evaluated the DBO durlobactam as an inhibitor of BlaC, the Mtb β-lactamase, and multiple Mtb peptidoglycan transpeptidases (PonA1, Ldt_Mt1, Ldt_Mt2, Ldt_Mt3, and Ldt_Mt5). Timed electrospray ionization mass spectrometry (ESI-MS) captured acyl-enzyme complexes with BlaC and all transpeptidases except Ldt_Mt5. Inhibition kinetics demonstrated durlobactam was a potent and efficient DBO inhibitor of BlaC (K_I app 9.2 ± 0.9 μM, k₂/K 5600 ± 560 M^–1 s^–1) and similar to clavulanate (K_I app 3.3 ± 0.6 μM, k₂/K 8400 ± 840 M^–1 s^–1); however, durlobactam had a lower turnover number (t_n = k_cat/k_inact) than clavulanate (1 and 8, respectively). K_I app values with durlobactam and clavulanate were similar for peptidoglycan transpeptidases, but ESI-MS captured durlobactam complexes at more time points. Molecular docking and simulation demonstrated several productive interactions of durlobactam in the active sites of BlaC, PonA1, and Ldt_Mt2. Antibiotic susceptibility testing was conducted on 11 Mtb isolates with amoxicillin, ceftriaxone, meropenem, imipenem, clavulanate, and durlobactam. Durlobactam had a minimum inhibitory concentration (MIC) range of 0.5–16 μg/mL, similar to the ranges for meropenem (1–32 μg/mL) and imipenem (0.5–64 μg/mL). In β-lactam + durlobactam combinations (1:1 mass/volume), MICs were lowered 4- to 64-fold for all isolates except one with meropenem–durlobactam. This work supports further exploration of novel β-lactamase inhibitors that target BlaC and Mtb peptidoglycan transpeptidases.

The antibacterial activity of silver species is well-established; however, their mechanism of action has not been adequately explored. Furthermore, issues of low-molecular silver compounds with cytotoxicity, stability, and solubility hamper their progress to drug leads. We have investigated silver N-heterocyclic carbene (NHC) halido complexes [(NHC)AgX, X = Cl, Br, and I] as a promising new type of antibacterial silver organometallics. Spectroscopic studies and conductometry established a higher stability for the complexes with iodide ligands, and nephelometry indicated that the complexes could be administered in solutions with physiological chloride levels. The complexes showed a broad spectrum of strong activity against pathogenic Gram-negative bacteria. However, there was no significant activity against Gram-positive strains. Further studies clarified that tryptone and yeast extract, as components of the culture media, were responsible for this lack of activity. The reduction of biofilm formation and a strong inhibition of both glutathione and thioredoxin reductases with IC₅₀ values in the nanomolar range were confirmed for selected compounds. In addition to their improved physicochemical properties, the compounds with iodide ligands did not display cytotoxic effects, unlike the other silver complexes. In summary, silver NHC complexes with iodide secondary ligands represent a useful scaffold for nontoxic silver organometallics with improved physicochemical properties and a distinct mechanism of action that is based on inhibition of thioredoxin and glutathione reductases.