Host Protease Activity on Bacterial Pathogens Promotes Complement and Antibiotic-Directed Killing.
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ABSTRACT:
SUBMITTER: Chen S
PROVIDER: S-EPMC8618517 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:We sought a new approach to treating infections by intracellular bacteria, namely, by altering host cell functions that support their growth. We screened a library of 640 Food and Drug Administration (FDA)-approved compounds for agents that render THP-1 cells resistant to infection by four intracellular pathogens. We identified numerous drugs that are not antibiotics but were highly effective in inhibiting intracellular bacterial growth with limited toxicity to host cells. These compounds are likely to target three kinds of host functions: (i) G protein-coupled receptors, (ii) intracellular calcium signals, and (iii) membrane cholesterol distribution. The compounds that targeted G protein receptor signaling and calcium fluxes broadly inhibited Coxiella burnetii, Legionella pneumophila, Brucella abortus, and Rickettsia conorii, while those directed against cholesterol traffic strongly attenuated the intracellular growth of C. burnetii and L. pneumophila. These pathways probably support intracellular pathogen growth so that drugs that perturb them may be therapeutic candidates. Combining host- and pathogen-directed treatments is a strategy to decrease the emergence of drug-resistant intracellular bacterial pathogens. Importance: Although antibiotic treatment is often successful, it is becoming clear that alternatives to conventional pathogen-directed therapy must be developed in the face of increasing antibiotic resistance. Moreover, the costs and timing associated with the development of novel antimicrobials make repurposed FDA-approved drugs attractive host-targeted therapeutics. This paper describes a novel approach of identifying such host-targeted therapeutics against intracellular bacterial pathogens. We identified several FDA-approved drugs that inhibit the growth of intracellular bacteria, thereby implicating host intracellular pathways presumably utilized by bacteria during infection.
| S-EPMC4128363 | biostudies-literature
Project description:Diminished antibiotic susceptibility of bacterial pathogens is an increasingly serious threat to human and animal health. Alternative strategies are required to combat antibiotic refractory bacteria. Bacterial metabolic state has been shown to play a critical role in its susceptibility to antibiotic killing. However, the adjuvant potential of nucleotides in combination with antibiotics to kill Gram-negative pathogens remains unknown. Herein, we found that thymine potentiated ciprofloxacin killing against both sensitive and resistant-E. coli in a growth phase-independent manner. Similar promotion effects were also observed for other bactericidal antibiotics, including ampicillin and kanamycin, in the fight against four kinds of Gram-negative bacteria. The mechanisms underlying this finding were that exogenous thymine could upregulate bacterial metabolism including increased TCA cycle and respiration, which thereby promote the production of ATP and ROS. Subsequently, metabolically inactive bacteria were converted to active bacteria and restored its susceptibility to antibiotic killing. In Galleria mellonella infection model, thymine effectively improved ciprofloxacin activity against E. coli. Taken together, our results demonstrated that thymine potentiates bactericidal antibiotics activity against Gram-negative pathogens through activating bacterial metabolism, providing a universal strategy to overcome Gram-negative pathogens.
| S-EPMC7875874 | biostudies-literature
Project description: Not available
| S-EPMC11346726 | biostudies-literature
Project description:BackgroundRespiratory tract infections represent a significant public health risk, and timely and accurate detection of bacterial infections facilitates rapid therapeutic intervention. Furthermore, monitoring the progression of infections after intervention enables 'course correction' in cases where initial treatments are ineffective, avoiding unnecessary drug dosing that can contribute to antibiotic resistance. However, current diagnostic and monitoring techniques rely on non-specific or slow readouts, such as radiographic imaging and sputum cultures, which fail to specifically identify bacterial infections and take several days to identify optimal antibiotic treatments.MethodsHere we describe a nanoparticle system that detects P. aeruginosa lung infections by sensing host and bacterial protease activity in vivo, and that delivers a urinary detection readout. One protease sensor is comprised of a peptide substrate for the P. aeruginosa protease LasA. A second sensor designed to detect elastases is responsive to recombinant neutrophil elastase and secreted proteases from bacterial strains.FindingsIn mice infected with P. aeruginosa, nanoparticle formulations of these protease sensors-termed activity-based nanosensors (ABNs)-detect infections and monitor bacterial clearance from the lungs over time. Additionally, ABNs differentiate between appropriate and ineffective antibiotic treatments acutely, within hours after the initiation of therapy.InterpretationThese findings demonstrate how activity measurements of disease-associated proteases can provide a noninvasive window into the dynamic process of bacterial infection and resolution, offering an opportunity for detecting, monitoring, and characterizing lung infections. FUND: National Cancer Institute, National Institute of Environmental Health Sciences, National Institutes of Health, National Science Foundation Graduate Research Fellowship Program, and Howard Hughes Medical Institute.
| S-EPMC6306379 | biostudies-literature
Project description:The ability of serum complement to kill Gram-negative bacteria requires assembly of the membrane attack complex (MAC) on the cell surface. The molecular events that lead to cell killing after MAC assembly are unknown. We have investigated the effect of C9 on bacterial survival in the presence and absence of its receptor, the C5b-8 complex, on the outer membrane. A fluorescence assay of the membrane potential across the inner bacterial membrane revealed that addition of C9 to cells bearing the performed C5b-8 complex caused a rapid and complete dissipation of the membrane potential. No fluorescence change was observed in serum-resistant strains of Escherichia coli. Addition of trypsin, after C9 was bound to C5b-8, did not rescue the cells from the lethal effects of C9. Furthermore, assays of cell killing kinetics and C9 binding indicate that formation of tubular poly(C9) is not required for killing. When C9 was introduced into the periplasmic space in the absence of its receptor by means of an osmotic shock procedure, cell killing occurred. Other proteins, such as C8 or serum albumin, were not toxic, and C9 was ineffective against two resistant strains. The results presented here and previously [Dankert & Esser (1986) Biochemistry 25, 1094-1100], when considered together, indicate that the 'lethal unit' in complement killing of some Gram-negative bacteria is a C9-derived product that acts by dissipation of cellular energy.
| S-EPMC1148004 | biostudies-other
Project description:[Figure: see text].
| S-EPMC8442908 | biostudies-literature
Project description:Objectives:The role of protease-activated receptor 1 (PAR1) in the pathogenesis of pneumonia and sepsis is ambiguous given the existing literature. As PAR1 is classically activated by the coagulation-based protease thrombin and leads to vascular leakage, our hypothesis was that PAR1 blockade with SCH79797 would be therapeutically beneficial in an experimental model of murine Gram-negative pneumonia. Methods:In this study, we administered SCH79797 via the intrapulmonary route 6?h after the establishment of Escherichia coli pneumonia and observed a significant improvement in survival, lung injury, bacterial clearance and inflammation. We focused on neutrophils as a potential target of the PAR1 antagonist, since they are the predominant inflammatory cell type in the infected lung. Results:Neutrophils appear to express PAR1 at low levels and the PAR1 antagonist SCH79797 enhanced neutrophil killing. Part of this effect may be explained by alterations in the generation of reactive oxygen species (ROS). SCH79797 also led to robust neutrophil extracellular trap (NET) generation and cathelicidin-related antimicrobial peptide (CRAMP) release by neutrophils. Surprisingly, SCH79797 also had a potent, direct antibiotic effect with disruption of the E. coli cell membrane. However, the newer-generation PAR1 antagonist, vorapaxar (SCH530348), had no appreciable effect on neutrophil activity or direct bacterial killing, which suggests the effects seen with SCH79797 may be PAR1 independent. Conclusions:In summary, we observed that intrapulmonary treatment with SCH79797 has significant therapeutic effects in a model of E. coli pneumonia that appear to be due, in part, to both neutrophil-stimulating and direct antibacterial effects of SCH79797.
| S-EPMC5961356 | biostudies-literature
Project description:Bacterial pathogens are associated with severe infections (e.g., sepsis) and exacerbation of debilitating conditions such as chronic obstructive pulmonary disease (COPD). The interactions of bacterial pathogens with macrophages, a key component of innate immunity and host defense, are not clearly understood and continue to be intensively studied. Having previously demonstrated a role of Wnt5A signaling in phagocytosis, we proceeded to decipher the connection of Wnt5A signaling with infection by pathogenic bacteria, namely Pseudomonas aeruginosa (PA) and Streptococcus pneumoniae (SP), which are related with the progression of COPD and sepsis. We found that during the initial hours of infection with PA and SP, there is decrease in the steady state levels of the Wnt5A protein in macrophages. Suppression of Wnt5A signaling, moreover, impairs macrophage clearance of the bacterial infection both in vitro and in vivo. Activation of Wnt5A signaling, on the other hand, enhances clearance of the infection. Macrophage-mediated containment of bacterial infection in our study is dependant on Wnt5A-induced Rac1/Disheveled activation and cytochalasin D inhibitable actin assembly, which is associated with ULK1 kinase activity and LC3BII accumulation. Our experimental findings are consistent with Wnt5A signaling-dependent induction of autophagic killing (xenophagy) of PA and SP, as further substantiated by transmission electron microscopy. Overall, our study unveils the prevalence of a Wnt5A-Rac1-Disheveled-mediated actin-associated autophagy circuit as an important component of innate immunity in host macrophages that may turn out crucial for restricting infection by leading bacterial pathogens.
| S-EPMC5900007 | biostudies-literature
Project description:Earlier, we reported that three Food and Drug Administration-approved drugs, trifluoperazine (TFP; an antipsychotic), amoxapine (AXPN; an antidepressant), and doxapram (DXP; a breathing stimulant), identified from an in vitro murine macrophage cytotoxicity screen, provided mice with 40 to 60% protection against pneumonic plague when administered at the time of infection for 1 to 3 days. In the present study, the therapeutic potential of these drugs against pneumonic plague in mice was further evaluated when they were administered at up to 48 h postinfection. While the efficacy of TFP was somewhat diminished as treatment was delayed to 24 h, the protection of mice with AXPN and DXP increased as treatment was progressively delayed to 24 h. At 48 h postinfection, these drugs provided the animals with significant protection (up to 100%) against challenge with the agent of pneumonic or bubonic plague when they were administered in combination with levofloxacin. Likewise, when they were used in combination with vancomycin, all three drugs provided mice with 80 to 100% protection from fatal oral Clostridium difficile infection when they were administered at 24 h postinfection. Furthermore, AXPN provided 40 to 60% protection against respiratory infection with Klebsiella pneumoniae when it was administered at the time of infection or at 24 h postinfection. Using the same in vitro cytotoxicity assay, we identified an additional 76/780 nonantibiotic drugs effective against K. pneumoniae For Acinetobacter baumannii, 121 nonantibiotic drugs were identified to inhibit bacterium-induced cytotoxicity in murine macrophages. Of these 121 drugs, 13 inhibited the macrophage cytotoxicity induced by two additional multiple-antibiotic-resistant strains. Six of these drugs decreased the intracellular survival of all three A. baumannii strains in macrophages. These results provided further evidence of the broad applicability and utilization of drug repurposing screening to identify new therapeutics to combat multidrug-resistant pathogens of public health concern.
| S-EPMC5740341 | biostudies-literature
Project description:Altered microbiota has been associated with a number of diseases, including inflammatory bowel diseases, diabetes, and cancer. This dysregulation is thought to relate the host inflammatory response to enteric pathogens. Macrophages play a key role in host response to microbes and are involved in bacterial killing and clearance. This process is partially mediated through the potassium efflux-dependent, cytosolic, PYCARD-containing inflammasome protein complex. Surprisingly, we discovered an alternative mechanism for bacterial killing, independent of the NLRP3 inflammasome/PYCARD. Using the NLRP3 inflammasome-deficient Raw 264.7 and PYCARD-deficient J77 macrophages, which both lack PYCARD, we found that the potassium efflux activator nigericin enhances bacterial killing. Macrophage response to nigericin was examined by RT gene profiling and subsequent qPCR, which demonstrated altered expression of a series of genes involved in the IL-18 bacterial killing pathway. Based on our results we propose a model of bacterial killing, unrelated to NLRP3 inflammasome activation in macrophage cells. Improving understanding of the molecular pathways driving bacterial clearance within macrophage cells will aid in the development of novel immune-targeted therapeutics in a number of diseases.
| S-EPMC6779719 | biostudies-literature