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Microbiology Spectrum Jun 2024is a leading cause of healthcare-associated infections globally. Vancomycin-resistant (VRSA), those with high-level resistance [minimum inhibitory concentration (MIC)...
UNLABELLED
is a leading cause of healthcare-associated infections globally. Vancomycin-resistant (VRSA), those with high-level resistance [minimum inhibitory concentration (MIC) of 16-32 µg/mL vancomycin], are uncommon, whereas vancomycin-intermediate (VISA; MIC of 4-8 µg/mL), are isolated more frequently and develop during long-term and/or repeated use of the antibiotic. VISA can be difficult to eradicate and infections may persist. Our knowledge of mechanisms that underlie the development of VISA is incomplete. We used a genomics approach to investigate the VISA phenotype in three prominent lineages. All VISA clinical isolates tested had increased cell wall thickness compared with vancomycin-susceptible strains. Growth rates of clonal complex (CC) 5, CC8, and CC45 clinical isolates were reduced in 2 µg/mL vancomycin compared to media alone. Culture in 2 and 4 µg/mL vancomycin sequentially for two weeks reduced susceptibility to daptomycin, televancin, tigecycline, and vancomycin in a majority of CC5, CC8, and CC45 isolates tested. We identified alleles reported previously to contribute to the VISA phenotype, but unexpectedly, these alleles were unique to each CC. A subtherapeutic concentration of vancomycin elicited changes in the VISA transcriptome-common and unique-among the three CCs tested. Multiple genes, including those encoding a glycerate kinase, an M50 family metallopeptidase, and an uncharacterized membrane protein, were upregulated among all three lineages and not reported previously as associated with VISA. Although there are lineage-specific changes in DNA sequence, our findings suggest changes in the VISA transcriptome constitute a general response to stress that confers reduced susceptibility to multiple antibiotics.
IMPORTANCE
Our understanding of the mechanisms that underlie the development of vancomycin-intermediate (VISA) is incomplete. To provide a more comprehensive view of this process, we compared genome sequences of clonal complex (CC) 5, CC8, and CC45 VISA clinical isolates and measured changes in the transcriptomes of these isolates during culture with a subtherapeutic concentration of vancomycin. Notably, we identified differentially expressed genes that were lineage-specific or common to the lineages tested, including genes that have not been previously reported to contribute to a VISA phenotype. Changes in gene expression were accompanied by reduced growth rate, increased cell wall thickness, and reduced susceptibility to daptomycin, televancin, tigecycline, and vancomycin. Our results provide support to the idea that changes in gene expression contribute to the development of VISA among three CCs that are a prominent cause of human infections.
PubMed: 38916317
DOI: 10.1128/spectrum.00486-24 -
Microbiology Spectrum Jun 2024is a microaerophilic Gram-negative bacterium that resides in the human stomach and is classified as a class I carcinogen for gastric cancer. Numerous studies have...
is a microaerophilic Gram-negative bacterium that resides in the human stomach and is classified as a class I carcinogen for gastric cancer. Numerous studies have demonstrated that infection plays a role in regulating the function of host cells, thereby contributing to the malignant transformation of these cells. However, infection is a chronic process, and short-term cellular experiments may not provide a comprehensive understanding of the situation, especially when considering the lower oxygen levels in the human stomach. In this study, we aimed to investigate the mechanisms underlying gastric cell dysfunction after prolonged exposure to under hypoxic conditions. We conducted a co-culture experiment using the gastric cell line GES-1 and for 30 generations under intermittent hypoxic conditions. By closely monitoring cell proliferation, migration, invasion, autophagy, and apoptosis, we revealed that sustained stimulation under hypoxic conditions significantly influences the function of GES-1 cells. This stimulation induces epithelial-mesenchymal transition and contributes to the propensity for malignant transformation of gastric cells. To confirm the results, we conducted an experiment involving Mongolian gerbils infected with for 85 weeks. All the results strongly suggest that the Nod1 receptor signaling pathway plays a crucial role in -related apoptosis and autophagy. In summary, continuous stimulation by affects the functioning of gastric cells through the Nod1 receptor signaling pathway, increasing the likelihood of cell carcinogenesis. The presence of hypoxic conditions further exacerbates this process.IMPORTANCEDeciphering the collaborative effects of infection on gastric epithelial cell function is key to unraveling the development mechanisms of gastric cancer. Prior research has solely examined the outcomes of short-term stimulation on gastric epithelial cells under aerobic conditions, neglecting the bacterium's nature as a microaerophilic organism that leads to cancer following prolonged stomach colonization. This study mimics a more genuine infection scenario by repeatedly exposing gastric epithelial cells to under hypoxic conditions for up to 30 generations. The results show that chronic exposure to in hypoxia substantially increases cell migration, invasion, and epithelial-mesenchymal transition, while suppressing autophagy and apoptosis. This highlights the significance of hypoxic conditions in intensifying the carcinogenic impact of infection. By accurately replicating the gastric environment, this study enhances our comprehension of 's pathogenic mechanisms in gastric cancer.
PubMed: 38916312
DOI: 10.1128/spectrum.00311-24 -
MBio Jun 2024causes cryptococcosis, one of the most prevalent fungal diseases, generally characterized by meningitis. There is a limited and not very effective number of drugs...
UNLABELLED
causes cryptococcosis, one of the most prevalent fungal diseases, generally characterized by meningitis. There is a limited and not very effective number of drugs available to combat this disease. In this manuscript, we show the host defense peptide mimetic brilacidin (BRI) as a promising antifungal drug against . BRI can affect the organization of the cell membrane, increasing the fungal cell permeability. We also investigated the effects of BRI against the model system by analyzing libraries of mutants grown in the presence of BRI. In , BRI also affects the cell membrane organization, but in addition the cell wall integrity pathway and calcium metabolism. experiments show BRI significantly reduces survival inside macrophages and partially clears lung infection in an immunocompetent murine model of invasive pulmonary cryptococcosis. We also observed that BRI interacts with caspofungin (CAS) and amphotericin (AmB), potentiating their mechanism of action against . BRI + CAS affects endocytic movement, calcineurin, and mitogen-activated protein kinases. Our results indicate that BRI is a novel antifungal drug against cryptococcosis.
IMPORTANCE
Invasive fungal infections have a high mortality rate causing more deaths annually than tuberculosis or malaria. Cryptococcosis, one of the most prevalent fungal diseases, is generally characterized by meningitis and is mainly caused by two closely related species of basidiomycetous yeasts, and . There are few therapeutic options for treating cryptococcosis, and searching for new antifungal agents against this disease is very important. Here, we present brilacidin (BRI) as a potential antifungal agent against . BRI is a small molecule host defense peptide mimetic that has previously exhibited broad-spectrum immunomodulatory/anti-inflammatory activity against bacteria and viruses. BRI alone was shown to inhibit the growth of , acting as a fungicidal drug, but surprisingly also potentiated the activity of caspofungin (CAS) against this species. We investigated the mechanism of action of BRI and BRI + CAS against . We propose BRI as a new antifungal agent against cryptococcosis.
PubMed: 38916308
DOI: 10.1128/mbio.01031-24 -
Frontiers in Cellular and Infection... 2024The naturally occurring dipeptide Tryptophylglycine (WG) is enhanced in human immunodeficiency virus (HIV-1) infected Elite Controllers (EC). We have shown that this...
INTRODUCTION
The naturally occurring dipeptide Tryptophylglycine (WG) is enhanced in human immunodeficiency virus (HIV-1) infected Elite Controllers (EC). We have shown that this dipeptide has an anti-HIV-1 effect and evaluated now its synergistic antiretroviral activity, in combination with current antiretrovirals against multi-drug resistant HIV-1 isolates.
METHODS
Drug selectivity assay with WG-am and ARVs agains HIV-1 resistant isolates were carried out. Subsequently, two methods, Chou-Talalay's Combination Index (CI) and ZIP synergy score (SS), were used to quantify the synergism.
RESULTS
WG-am had a moderate/strong synergism with the four tested antiretrovirals: raltegravir, tenofovir, efavirenz, darunavir. WG-am:TDF had strong synergism at ED50, ED75, ED90 (CI: <0.2) in isolates resistant to protease inhibitors or integrase strand inhibitors (INSTI), and a slightly less synergism in isolates resistant to non-nucleoside or nucleotide reverse transcriptase inhibitors. WG-am combined with each of the four drugs inhibited all drug-resistant isolates with over 95% reduction at maximum concentration tested. The highest selectivity indexes (CC50/ED50) were in INSTI-resistant isolates.
CONCLUSION
Our data suggest that WG, identified as occurring and enhanced in Elite Controllers has a potential to become a future treatment option in patients with HIV-1 strains resistant to any of the four major categories of anti-HIV-1 compounds.
Topics: HIV-1; Drug Synergism; Humans; Dipeptides; HIV Infections; Anti-HIV Agents; Microbial Sensitivity Tests; Drug Resistance, Viral
PubMed: 38915925
DOI: 10.3389/fcimb.2024.1334126 -
Frontiers in Cellular and Infection... 2024The primary aim of this study is to investigate the correlation between serum levels of fibrinogen-to-prealbumin ratio (FPR) and C-reactive protein-to-prealbumin ratio...
BACKGROUND
The primary aim of this study is to investigate the correlation between serum levels of fibrinogen-to-prealbumin ratio (FPR) and C-reactive protein-to-prealbumin ratio (CPR) and prognostic outcomes among patients with severe fever with thrombocytopenia syndrome (SFTS). SFTS, characterized by elevated mortality rates, represents a substantial public health challenge as an emerging infectious disease.
METHODS
The study included 159 patients with SFTS. Clinical and laboratory data were compared between the survival and death groups. Univariate and multivariate logistic regression analysis were utilized to identify independent risk factors for mortality. The predictive efficacy of FPR and CPR was evaluated using receiver operating characteristic (ROC) curve. Survival analysis was conducted using the Kaplan-Meier curve and the log-rank test was employed for comparison.
RESULTS
The death group exhibited significantly elevated levels of FPR and CPR compared to the survival group ( < 0.05). Multivariate logistic regression analysis confirmed that both FPR and CPR independently correlated with a poorer prognosis among patients with SFTS. The ROC curve analysis indicated that FPR and CPR had superior predictive capabilities compared to C-reactive protein and fibrinogen. Kaplan-Meier survival analysis demonstrated that patients with SFTS who have FPR > 0.045 (log-rank test; χ2 = 17.370, < 0.001) or CPR > 0.05 (log-rank test; χ2 = 19.442, < 0.001) experienced significantly lower survival rates within a 30-day follow-up period.
CONCLUSION
Elevated levels of FPR and CPR serve as distinct risk factors for mortality among patients with SFTS, indicating their potential to predict an unfavorable prognosis in these patients.
Topics: Humans; C-Reactive Protein; Male; Female; Fibrinogen; Prognosis; Middle Aged; Aged; Severe Fever with Thrombocytopenia Syndrome; ROC Curve; Prealbumin; Biomarkers; Risk Factors; Adult; Phlebovirus; Kaplan-Meier Estimate; Retrospective Studies
PubMed: 38915920
DOI: 10.3389/fcimb.2024.1397789 -
Frontiers in Endocrinology 2024Type 2 diabetes (T2D) is a polygenic metabolic disorder characterized by insulin resistance in peripheral tissues and impaired insulin secretion by the pancreas. While... (Review)
Review
Type 2 diabetes (T2D) is a polygenic metabolic disorder characterized by insulin resistance in peripheral tissues and impaired insulin secretion by the pancreas. While the decline in insulin production and secretion was previously attributed to apoptosis of insulin-producing β-cells, recent studies indicate that β-cell apoptosis rates are relatively low in diabetes. Instead, β-cells primarily undergo dedifferentiation, a process where they lose their specialized identity and transition into non-functional endocrine progenitor-like cells, ultimately leading to β-cell failure. The underlying mechanisms driving β-cell dedifferentiation remain elusive due to the intricate interplay of genetic factors and cellular stress. Understanding these mechanisms holds the potential to inform innovative therapeutic approaches aimed at reversing β-cell dedifferentiation in T2D. This review explores the proposed drivers of β-cell dedifferentiation leading to β-cell failure, and discusses current interventions capable of reversing this process, thus restoring β-cell identity and function.
Topics: Humans; Insulin-Secreting Cells; Cell Dedifferentiation; Diabetes Mellitus, Type 2; Animals; Cell Differentiation; Apoptosis; Insulin Secretion
PubMed: 38915897
DOI: 10.3389/fendo.2024.1414447 -
Frontiers in Cardiovascular Medicine 2024Immune checkpoint inhibitor (ICI)-induced myocarditis is a rare immune-related adverse event (irAE) with a fatality rate of 40%-46%. However, irMyocarditis can be...
BACKGROUND
Immune checkpoint inhibitor (ICI)-induced myocarditis is a rare immune-related adverse event (irAE) with a fatality rate of 40%-46%. However, irMyocarditis can be asymptomatic. Thus, improved monitoring, detection and therapy are needed. This study aims to generate knowledge on pathogenesis and assess outcomes in cancer centers with intensified patient management.
METHODS
Patients with cardiac irAEs from the SERIO registry (www.serio-registry.org) were analyzed for demographics, ICI-related information (type of ICI, therapy line, combination with other drugs, onset of irAE, and tumor response), examination results, irAE treatment and outcome, as well as oncological endpoints. Cardiac biopsies of irMyocarditis cases ( = 12) were analyzed by Nanostring and compared to healthy heart muscle ( = 5) and longitudinal blood sampling was performed for immunophenotyping of irMyocarditis-patients ( = 4 baseline and = 8 during irAE) in comparison to patients without toxicity under ICI-therapy ( = 4 baseline and = 7 during ICI-therapy) using flow cytometry.
RESULTS
A total of 51 patients with 53 cardiac irAEs induced by 4 different ICIs (anti-PD1, anti-PD-L1, anti-CTLA4) were included from 12 centers in 3 countries. Altogether, 83.0% of cardiac irAEs were graded as severe or life-threatening, and 11.3% were fatal (6/53). Thus, in centers with established consequent troponin monitoring, work-up upon the rise in troponin and consequent treatment of irMyocarditis with corticosteroids and -if required-second-line therapy mortality rate is much lower than previously reported. The median time to irMyocarditis was 36 days (range 4-1,074 days) after ICI initiation, whereas other cardiotoxicities, e.g. asystolia or myocardiopathy, occurred much later. The cytokine-mediated signaling pathway was differentially regulated in myocardial biopsies as compared to healthy heart based on enrichment Gene Ontology analysis. Additionally, longitudinal peripheral blood mononuclear cell (PBMC) samples from irMyocarditis-patients indicated ICI-driven enhanced CD4+ Treg cells and reduced CD4+ T cells. Immunophenotypes, particularly effector memory T cells of irMyocarditis-patients differed from those of ICI-treated patients without side effects. LAG3 expression on T cells and PD-L1 expression on dendritic cells could serve as predictive indicators for the development of irMyocarditis.
CONCLUSION
Interestingly, our cohort shows a very low mortality rate of irMyocarditis-patients. Our data indicate so far unknown local and systemic immunological patterns in cardiotoxicity.
PubMed: 38915743
DOI: 10.3389/fcvm.2024.1408586 -
BioRxiv : the Preprint Server For... Jun 2024Tripartite resistance nodulation and cell division multidrug efflux pumps span the periplasm and are a major driver of multidrug resistance among Gram-negative bacteria....
Tripartite resistance nodulation and cell division multidrug efflux pumps span the periplasm and are a major driver of multidrug resistance among Gram-negative bacteria. The periplasm provides a distinct environment between the inner and outer membranes of Gram-negative bacteria. Cations, such as Mg , become concentrated within the periplasm and, in contrast to the cytoplasm, its pH is sensitive to conditions outside the cell. Here, we reveal an interplay between Mg and pH in modulating the dynamics of the periplasmic adaptor protein, AcrA, and its function within the prototypical AcrAB-TolC multidrug efflux pump from . In the absence of Mg , AcrA becomes increasingly plastic within acidic conditions, but when Mg is bound this is ameliorated, resulting in domain specific organisation in neutral to weakly acidic regimes. We establish a unique histidine residue directs these structural dynamics and is essential for sustaining pump efflux activity across acidic, neutral, and alkaline conditions. Overall, we propose Mg conserves the structural mobility of AcrA to ensure optimal AcrAB-TolC function within rapid changing environments commonly faced by the periplasm during bacterial infection and colonization. This work highlights that Mg is an important mechanistic component in this pump class and possibly across other periplasmic lipoproteins.
PubMed: 38915626
DOI: 10.1101/2024.06.10.597921 -
BioRxiv : the Preprint Server For... Jun 2024Telomeric DNA, composed of short, direct repeats, is of crucial importance for chromosome stability. Due to intrinsic problems with replicating this DNA, the repeat...
Telomeric DNA, composed of short, direct repeats, is of crucial importance for chromosome stability. Due to intrinsic problems with replicating this DNA, the repeat tracts shorten at each cell division. Once repeat tracts become critically short, a telomeric stress signal induces cellular senescence and division arrest, which eventually may lead to devastating age-related degenerative diseases associated with dysfunctional telomers. Conversely, maintenance of telomere length by telomerase upregulation is a hallmark of cancer. Therefore, telomere length is a critical determinant of telomere function. How telomere length is established and molecular mechanisms for telomere-specific length regulation remained unknown. Here we show that subtelomeric chromatin is a determinant for how telomere equilibrium set-length is established in . The results demonstrate that telomerase recruitment mediated by the telomere-associated Sir4 protein is modulated on chromosome 3L in a telomere-specific way. Increased Sir4 abundance on subtelomeric heterochromatin of this specific telomere leads to telomere lengthening of only that telomere in , but not at other telomeres. Therefore, this work describes a mechanism for a how telomere-specific repeat tract length can be established. Further, our results will force the evaluation of telomere length away from a generalized view to a more telomere-specific consideration.
PubMed: 38915611
DOI: 10.1101/2024.06.12.598646 -
BioRxiv : the Preprint Server For... Jun 2024Cells are among the most dynamic entities, constantly undergoing various processes such as growth, division, movement, and interaction with other cells as well as the...
Cells are among the most dynamic entities, constantly undergoing various processes such as growth, division, movement, and interaction with other cells as well as the environment. Time-lapse microscopy is central to capturing these dynamic behaviors, providing detailed temporal and spatial information that allows biologists to observe and analyze cellular activities in real-time. The analysis of time-lapse microscopy data relies on two fundamental tasks: cell segmentation and cell tracking. Integrating deep learning into bioimage analysis has revolutionized cell segmentation, producing models with high precision across a wide range of biological images. However, developing generalizable deep-learning models for tracking cells over time remains challenging due to the scarcity of large, diverse annotated datasets of time-lapse movies of cells. To address this bottleneck, we propose a GAN-based time-lapse microscopy generator, termed tGAN, designed to significantly enhance the quality and diversity of synthetic annotated time-lapse microscopy data. Our model features a dual-resolution architecture that adeptly synthesizes both low and high-resolution images, uniquely capturing the intricate dynamics of cellular processes essential for accurate tracking. We demonstrate the performance of tGAN in generating high-quality, realistic, annotated time-lapse videos. Our findings indicate that tGAN decreases dependency on extensive manual annotation to enhance the precision of cell tracking models for time-lapse microscopy.
PubMed: 38915545
DOI: 10.1101/2024.06.11.598572