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MSystems Jun 2024(), a facultative intracellular bacterium, is an important zoonotic pathogen that causes abscesses and pyogenic granulomas. The relationship between gut microbiota and...
UNLABELLED
(), a facultative intracellular bacterium, is an important zoonotic pathogen that causes abscesses and pyogenic granulomas. The relationship between gut microbiota and host health or diseases has received increasing attention. However, the role of gut microbiota in the process of infection is still unclear. In this study, we established a infection model in C57BL/6 mice and examined the impact of preemptive oral administration () on infection. Our findings revealed that infection led to pronounced pathological alterations in the liver and kidneys, characterized by abscess formation, intense inflammatory responses, and bacterial overload. Remarkably, these deleterious effects were greatly relieved by oral administration of before infection with . Additionally, we further found that during infection, peritoneal macrophages (PMs) of mice orally administered with accumulated more rapidly at sites of infection. Furthermore, our results showed that PMs from mice with oral administration showed a stronger clearance effect, and this was mediated by high expression of LC3-II protein. Meanwhile, oral administration of protected the gut microbiota disorder in C57BL/6 mice caused by infection. In summary, our study demonstrates that oral administration of confers effective protection against infection in C57BL/6 mice by modulating macrophage autophagy, thereby augmenting bacterial clearance and preserving gut microbiota and function stability. These findings position as a viable probiotic candidate for the clinical prevention of infection.
IMPORTANCE
(C. ) is known to induce a range of chronic diseases in both animals and humans. Currently, clinical treatment for C. infection mainly relies on antibiotic therapy or surgical intervention. However, excessive use of antibiotics may increase the risk of drug-resistant strains, and the effectiveness of treatment remains unsatisfactory. Furthermore, surgical procedures do not completely eradicate pathogens and can easily cause environmental pollution. Probiotic interventions are receiving increasing attention for improving the body's immune system and maintaining health. In this study, we established a C. infection model in C57BL/6 mice to explore the impact of acidophilus during C. infection. Our results showed that effectively protected against C. infection by regulating the autophagy of macrophages and maintaining intestinal microbiota homeostasis. This study may provide a new strategy for the prevention of C. infection.
PubMed: 38934644
DOI: 10.1128/msystems.00484-24 -
MBio Jun 2024Contemporary antifungal therapies utilized to treat filamentous fungal infections are inhibited by intrinsic and emerging drug resistance. Consequently, there is an...
Contemporary antifungal therapies utilized to treat filamentous fungal infections are inhibited by intrinsic and emerging drug resistance. Consequently, there is an urgent need to develop novel antifungal compounds that are effective against drug-resistant filamentous fungi. Here, we utilized an cell-based high-throughput screen to identify small molecules with antifungal activity that also potentiated triazole activity. The screen identified 16 hits with promising activity against . A nonspirocyclic piperidine, herein named MBX-7591, exhibited synergy with triazole antifungal drugs and activity against pan-azole-resistant isolates. MBX-7591 has additional potent activity against species and CO-dependent activity against . Chemical, genetic, and biochemical mode of action analyses revealed that MBX-7591 increases cell membrane saturation by decreasing oleic acid content. MBX-7591 has low toxicity and shows good efficacy in decreasing fungal burden in a murine model of invasive pulmonary aspergillosis. Taken together, our results suggest MBX-7591 is a promising hit with a novel mode of action for further antifungal drug development to combat the rising incidence of triazole-resistant filamentous fungal infections.IMPORTANCEThe incidence of infections caused by fungi continues to increase with advances in medical therapies. Unfortunately, antifungal drug development has not kept pace with the incidence and importance of fungal infections, with only three major classes of antifungal drugs currently available for use in the clinic. Filamentous fungi, also called molds, are particularly recalcitrant to contemporary antifungal therapies. Here, a recently developed cell reporter strain was utilized to conduct a high-throughput screen to identify small molecules with antifungal activity. An emphasis was placed on small molecules that potentiated the activity of contemporary triazole antifungals and led to the discovery of MBX-7591. MBX-7591 potentiates triazole activity against drug-resistant molds such as and has activity against Mucorales fungi. MBX-7591's mode of action involves inhibiting the conversion of saturated to unsaturated fatty acids, thereby impacting fungal membrane integrity. MBX-7591 is a novel small molecule with antifungal activity poised for lead development.
PubMed: 38934618
DOI: 10.1128/mbio.01166-24 -
MBio Jun 2024Type III interferon signaling contributes to the pathogenesis of the important human pathogen in the airway. Little is known of the cellular factors important in this...
Type III interferon signaling contributes to the pathogenesis of the important human pathogen in the airway. Little is known of the cellular factors important in this response. Using -green fluorescent protein reporter mice combined with flow cytometry and cellular depletion strategies, we demonstrate that the alveolar macrophage is the primary producer of interferon lambda (IFN-λ) in response to in the airway. Bone marrow chimeras showed reduced bacterial burden in IFN-λ receptor (IFNLR1)-deficient recipient mice, indicative that non-hematopoietic cells were important for pathogenesis, in addition to significant reductions in pulmonary inflammation. These observations were confirmed through the use of an airway epithelial-specific IFNLR knockout mouse. Our data suggest that upon entry to the airway, activates alveolar macrophages to produce type III IFN that is subsequently sensed by the airway epithelium. Future steps will determine how signaling from the epithelium then exerts its influence on bacterial clearance. These results highlight the important, yet sometimes detrimental, role of type III IFN signaling during infection and the impact the airway epithelium plays during host-pathogen interactions.IMPORTANCEThe contribution of type III interferon signaling to the control of bacterial infections is largely unknown. We have previously demonstrated that it contributes to the pathogenesis of acute respiratory infection. In this report, we document the importance of two cell types that underpin this pathogenesis. We demonstrate that the alveolar macrophage is the cell that is responsible for the production of type III interferon and that this molecule is sensed by airway epithelial cells, which impacts both bacterial clearance and induction of inflammation. This work sheds light on the first two aspects of this important pathogenic cascade.
PubMed: 38934617
DOI: 10.1128/mbio.01130-24 -
Microbiology Spectrum Jun 2024Some naturally occurring compounds, known for their antimicrobial activities, have been employed as food additives. However, their efficacy in treating infections caused...
UNLABELLED
Some naturally occurring compounds, known for their antimicrobial activities, have been employed as food additives. However, their efficacy in treating infections caused by antibiotic-resistant bacteria is yet to be fully explored. Rapidly growing mycobacteria (RGM), a category within nontuberculous mycobacteria (NTM), are prevalent in various environments and can lead to infections in humans. The rise of antimicrobial resistance within RGM is a documented concern. In this study, we reported that four specific natural compounds effectively inhibited the growth and biofilm formation of three key RGM pathogens , , and . We screened 12 natural compounds for their effectiveness against antibiotic-resistant clinical strains of RGM. Four compounds showed significant inhibitory effects from the most effective to least: -cinnamaldehyde, carvacrol, gentisaldehyde, and phloroglucinaldehyde. In the analysis of time-killing kinetics, gentisaldehyde and phloroglucinaldehyde displayed bactericidal activity while -cinnamaldehyde and carvacrol exhibited bacteriostatic effects. At 1× minimal inhibition concentrations, these compounds significantly reduced biofilm formation in all three RGM species to levels between 2.9% and 20.5% relative to controls. Checkerboard assays indicated synergistic interactions between these four compounds and antibiotics such as amikacin, clarithromycin, and linezolid. Of these 12 compound-antibiotic combinations, the pairs of carvacrol-linezolid, carvacrol-amikacin, and gentisaldehyde-clarithromycin demonstrated the most synergy against multiple RGM strains. Moreover, two other compounds citral and geraniol showed synergism with all three test antibiotics. Time-killing assays further confirmed most of synergistic combinations identified in the checkerboard tests. Our research suggests the potential of these essential oils and phenolic aldehydes, both individually and in combination with antibiotics, in treating RGM infections. In addition, this work illuminates applications of these natural compounds in environmental remediation to mitigate bacterial persistence for the control of infectious diseases.
IMPORTANCE
The emergence of antimicrobial resistance within rapidly growing mycobacteria (RGM) poses a significant threat to public health. This study investigates the potential of naturally occurring compounds to combat infections caused by antibiotic-resistant RGM including , , and . We identified four specific natural compounds showing impressive inhibitory effects against antibiotic-resistant clinical strains. These compounds not only inhibited the growth and biofilm formation but also exhibited synergistic interactions with antibiotics against key RGM pathogens. Our findings highlight the alternative treatment strategies for RGM infections and potential environmental applications of these natural compounds in mitigating microbial persistence and controlling infectious diseases.
PubMed: 38934606
DOI: 10.1128/spectrum.00199-24 -
Microbiology Spectrum Jun 2024, an organism recently classified within the Pseudomonadaceae family, has been detected in diverse sources such as human tissues, animal guts, industrial fermenters, and...
, an organism recently classified within the Pseudomonadaceae family, has been detected in diverse sources such as human tissues, animal guts, industrial fermenters, and decomposition environments, suggesting a diverse ecological role. However, a large knowledge gap exists in how functions. In this comparative genomic analysis, adaptations indicative of habitat specificity among strains and genomic similarity to known opportunistic pathogens are revealed. Genomic investigation reveals a core metabolic utilization of multiple oxidative and non-oxidative catabolic pathways, suggesting adaptability to varied environments and carbon sources. The genomic repertoire of includes secondary metabolites, such as antimicrobials and siderophores, indicative of its involvement in microbial competition and resource acquisition. Additionally, the presence of transposases, prophages, plasmids, and Clustered Regularly Interspaced Short Palindromic Repeats-Cas systems in genomes suggests mechanisms for horizontal gene transfer and defense against viral predation. This comprehensive genomic analysis expands our understanding on the ecological functions, community interactions, and potential virulence of , while emphasizing its adaptability and diverse capabilities across environmental and host-associated ecosystems.IMPORTANCEAs the microbial world continues to be explored, new organisms will emerge with beneficial and/or pathogenetic impact. is a species originally isolated from clinical human tissue and fluid samples but has not been attributed to disease. Since its classification, has been found in animal guts, animal waste, decomposing remains, and biogas fermentation reactors. This is the first study to provide an in-depth view of the metabolic potential of publicly available genomes belonging to this species through a comparative genomics and draft pangenome calculation approach. It was found that is metabolically versatile and likely adapts to diverse energy sources and environments, which may make it useful for bioremediation and in industrial settings. A range of virulence factors and antibiotic resistances were also detected, suggesting may operate as an undescribed opportunistic pathogen.
PubMed: 38934605
DOI: 10.1128/spectrum.04157-23 -
MSphere Jun 2024Bacterial ribonuclease E (RNase E) is vital for posttranscriptional regulation by degrading and processing RNA. The RraA protein inhibits RNase E activity through...
Bacterial ribonuclease E (RNase E) is vital for posttranscriptional regulation by degrading and processing RNA. The RraA protein inhibits RNase E activity through protein-protein interactions, exerting a global regulatory effect on gene expression. However, the specific role of RraA remains unclear. In this study, we investigated expression in ZJ-T and identified three promoters responsible for its expression, resulting in transcripts with varying 5'-UTR lengths. During the stationary phase, was significantly posttranscriptionally inhibited. Deletion of had no impact on bacterial growth in rich medium Luria-Bertani broth with salt (LBS) but resulted in decreased biofilm formation and increased resistance to polymyxin B. Transcriptome analysis revealed 350 differentially expressed genes (DEGs) between the wild type and the mutant, while proteome analysis identified 267 differentially expressed proteins (DEPs). Integrative analysis identified 55 genes common to both DEGs and DEPs, suggesting that RraA primarily affects gene expression at the posttranscriptional level. KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis demonstrated that RraA facilitates the conversion of fatty acids, propionic acid, and branched-chain amino acids to acetyl-CoA while enhancing amino acid and peptide uptake. Notably, RraA positively regulates the expression of virulence-associated genes, including those involved in biofilm formation and the type VI secretion system. This study expands the understanding of the regulatory network of RraA through transcriptome analysis, emphasizing the importance of proteomic analysis in investigating posttranscriptional regulation.IMPORTANCERraA is an inhibitor protein of ribonuclease E that interacts with and suppresses its endonucleolytic activity, thereby playing a widespread regulatory role in the degradation and maturation of diverse mRNAs and noncoding small RNAs. However, the physiological functions and associated regulon of RraA in have not been fully elucidated. Here, we report that RraA impacts virulence-associated physiological processes, namely, antibiotic resistance and biofilm formation, in . By conducting an integrative analysis of both the transcriptome and proteome, we revealed the involvement of RraA in carbon metabolism, amino acid catabolism, and transport, as well as in the type VI secretion system. Collectively, these findings elucidate the regulatory influence of RraA on multiple pathways associated with metabolism and pathogenesis in .
PubMed: 38934599
DOI: 10.1128/msphere.00020-24 -
MSystems Jun 2024Airway microbiota are known to contribute to lung diseases, such as cystic fibrosis (CF), but their contributions to pathogenesis are still unclear. To improve our...
Airway microbiota are known to contribute to lung diseases, such as cystic fibrosis (CF), but their contributions to pathogenesis are still unclear. To improve our understanding of host-microbe interactions, we have developed an integrated analytical and bioinformatic mass spectrometry (MS)-based metaproteomics workflow to analyze clinical bronchoalveolar lavage (BAL) samples from people with airway disease. Proteins from BAL cellular pellets were processed and pooled together in groups categorized by disease status (CF vs. non-CF) and bacterial diversity, based on previously performed small subunit rRNA sequencing data. Proteins from each pooled sample group were digested and subjected to liquid chromatography tandem mass spectrometry (MS/MS). MS/MS spectra were matched to human and bacterial peptide sequences leveraging a bioinformatic workflow using a metagenomics-guided protein sequence database and rigorous evaluation. Label-free quantification revealed differentially abundant human peptides from proteins with known roles in CF, like neutrophil elastase and collagenase, and proteins with lesser-known roles in CF, including apolipoproteins. Differentially abundant bacterial peptides were identified from known CF pathogens (e.g., ), as well as other taxa with potentially novel roles in CF. We used this host-microbe peptide panel for targeted parallel-reaction monitoring validation, demonstrating for the first time an MS-based assay effective for quantifying host-microbe protein dynamics within BAL cells from individual CF patients. Our integrated bioinformatic and analytical workflow combining discovery, verification, and validation should prove useful for diverse studies to characterize microbial contributors in airway diseases. Furthermore, we describe a promising preliminary panel of differentially abundant microbe and host peptide sequences for further study as potential markers of host-microbe relationships in CF disease pathogenesis.IMPORTANCEIdentifying microbial pathogenic contributors and dysregulated human responses in airway disease, such as CF, is critical to understanding disease progression and developing more effective treatments. To this end, characterizing the proteins expressed from bacterial microbes and human host cells during disease progression can provide valuable new insights. We describe here a new method to confidently detect and monitor abundance changes of both microbe and host proteins from challenging BAL samples commonly collected from CF patients. Our method uses both state-of-the art mass spectrometry-based instrumentation to detect proteins present in these samples and customized bioinformatic software tools to analyze the data and characterize detected proteins and their association with CF. We demonstrate the use of this method to characterize microbe and host proteins from individual BAL samples, paving the way for a new approach to understand molecular contributors to CF and other diseases of the airway.
PubMed: 38934598
DOI: 10.1128/msystems.00929-23 -
MSystems Jun 2024is the dominant species of the genus in the gut, which is genomically heterogeneous and difficult to isolate; hence, scarce research was carried out for this species....
UNLABELLED
is the dominant species of the genus in the gut, which is genomically heterogeneous and difficult to isolate; hence, scarce research was carried out for this species. This study aimed to investigate the effect of on hyperglycemia. Thirty-nine strains were isolated from healthy individuals, and three strains (HF2123, HF1478, and HF2130) that had the highest glucose consumption were selected to evaluate the effects of supplementation on hyperglycemia. Microbiomics and non-target metabolomics were used to uncover the underlying mechanisms. Oral administration of in diabetic db/db mice increased the expression and secretion of glucagon-like peptide-1 (GLP-1), significantly improved hyperglycemia, insulin resistance, and lipid accumulation, and alleviated the pathological morphology in the pancreas, liver, and colon. changed the composition of the gut microbiota of diabetic db/db mice, which was characterized by increasing the ratio of Bacteroidetes to Firmicutes and increasing the relative abundance of genera , , and . After intervention with , fecal metabolic profiling showed that fumaric acid and homocysteine contents decreased, and glutamine contents increased. Furthermore, amino acid metabolism and cAMP/PKA signaling pathways were enriched. Our findings indicate that improved glucose metabolism abnormalities in diabetic db/db mice. Especially, one of the strains, HF2130, has shown superior performance in improving hyperglycemia, which may have the potential as a probiotic against hyperglycemia.
IMPORTANCE
As a core member of the human intestinal ecosystem, has been associated with glucose metabolic homeostasis in previous studies. However, these results have often been derived from metagenomic studies, and the experimental studies have been based solely on the type of strain DSM 18205. Therefore, more experimental evidence from additional isolates is needed to validate the results according to their high genomic heterogeneity. In this study, we isolated different branches of strains and demonstrated that could improve the metabolic profile of hyperglycemic mice by modulating microbial activity. This finding supports the causal contribution of in host glucose metabolism.
PubMed: 38934548
DOI: 10.1128/msystems.00532-24 -
MSystems Jun 2024is a Gram-negative commensal bacterium commonly found in the human colon, which differentiates into two genomospecies termed divisions I and II. Through a comprehensive...
UNLABELLED
is a Gram-negative commensal bacterium commonly found in the human colon, which differentiates into two genomospecies termed divisions I and II. Through a comprehensive collection of 694 whole genome sequences, we identify novel features distinguishing these divisions. Our study reveals a distinct geographic distribution with division I strains predominantly found in North America and division II strains in Asia. Additionally, division II strains are more frequently associated with bloodstream infections, suggesting a distinct pathogenic potential. We report differences between the two divisions in gene abundance related to metabolism, virulence, stress response, and colonization strategies. Notably, division II strains harbor more antimicrobial resistance (AMR) genes than division I strains. These findings offer new insights into the functional roles of division I and II strains, indicating specialized niches within the intestine and potential pathogenic roles in extraintestinal sites.
IMPORTANCE
Understanding the distinct functions of microbial species in the gut microbiome is crucial for deciphering their impact on human health. Classifying division II strains as can lead to erroneous associations, as researchers may mistakenly attribute characteristics observed in division II strains to the more extensively studied division I . Our findings underscore the necessity of recognizing these divisions as separate species with distinct functions. We unveil new findings of differential gene prevalence between division I and II strains in genes associated with intestinal colonization and survival strategies, potentially influencing their role as gut commensals and their pathogenicity in extraintestinal sites. Despite the significant niche overlap and colonization patterns between these groups, our study highlights the complex dynamics that govern strain distribution and behavior, emphasizing the need for a nuanced understanding of these microorganisms.
PubMed: 38934546
DOI: 10.1128/msystems.00516-24 -
MSystems Jun 2024Gut microbiota of the bumblebee is critical as it modulates the health and fitness of the host. However, the mechanisms underlying the formation and maintenance of the...
UNLABELLED
Gut microbiota of the bumblebee is critical as it modulates the health and fitness of the host. However, the mechanisms underlying the formation and maintenance of the diversity of bumblebee gut bacteria over a long period of evolution have yet to be elucidated. In particular, the gut bacterial diversity and community assembly processes of across the Chinese border remain unclear. In this study, we systematically carried out unprecedented sampling of 513 workers of the species across the Chinese landscape and used full-length 16S rRNA gene sequencing to examine their gut microbiota diversity and biogeography. The gut microbiota composition and community structure of from different geographical locations were diverse. On the whole, the gut bacteria and are dominant in bumblebees, but opportunistic pathogens and are dominant in some sampling sites such as Hb15, Gs1, Gs45, Qhs15, and Ssx35. All or part of environmental factors such as latitude, annual mean temperature, elevation, human footprint, population density, and annual precipitation can affect the alpha diversity and community structure of gut bacteria. Further analysis showed that the assembly and shift of bumblebee gut bacterial communities under geographical variation were mainly driven by the stochastic drift of the neutral process rather than by variable selection of niche differentiation. In conclusion, our unprecedented sampling uncovers bumblebee gut microbiome diversity and shifts over evolutionary time.
IMPORTANCE
The microbiotas associated with organisms facilitates host health and fitness, and the homeostasis status of gut microbiota also reflects the habitat security faced by the host. In addition, managing gut microbiota is important to improve bumblebee health by understanding the ecological process of the gut microbiome. Thus, we first carried out an runprecedented sampling of 513 workers of the species across the Chinese landscape and used full-length 16S rRNA gene sequencing to uncover their gut microbiota diversity and biogeography. Our study provides new insights into the understanding of gut microbiome diversity and shifts for Chinese Bumblebee over evolutionary time.
PubMed: 38934544
DOI: 10.1128/msystems.00459-24