bacterial invasion
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2022 ◽  
Vol 23 (2) ◽  
pp. 860
Author(s):  
Isabella A. Joubert ◽  
Michael Otto ◽  
Tobias Strunk ◽  
Andrew J. Currie

Preterm infants are at increased risk for invasive neonatal bacterial infections. S. epidermidis, a ubiquitous skin commensal, is a major cause of late-onset neonatal sepsis, particularly in high-resource settings. The vulnerability of preterm infants to serious bacterial infections is commonly attributed to their distinct and developing immune system. While developmentally immature immune defences play a large role in facilitating bacterial invasion, this fails to explain why only a subset of infants develop infections with low-virulence organisms when exposed to similar risk factors in the neonatal ICU. Experimental research has explored potential virulence mechanisms contributing to the pathogenic shift of commensal S. epidermidis strains. Furthermore, comparative genomics studies have yielded insights into the emergence and spread of nosocomial S. epidermidis strains, and their genetic and functional characteristics implicated in invasive disease in neonates. These studies have highlighted the multifactorial nature of S. epidermidis traits relating to pathogenicity and commensalism. In this review, we discuss the known host and pathogen drivers of S. epidermidis virulence in neonatal sepsis and provide future perspectives to close the gap in our understanding of S. epidermidis as a cause of neonatal morbidity and mortality.


2021 ◽  
Author(s):  
Hanyu Sun ◽  
Yuki Chan ◽  
Xuan Li ◽  
Ruogu Xu ◽  
Zhengchuan Zhang ◽  
...  

Abstract Background and aimsSurface modifications of titanium implants play essential role in facilitating osteointegration and enhancing their antimicrobial properties, while the latter is critical for preventing infectious diseases caused by the biofilm. However, it remains unknown about how the surface modifications could affect the composition and functional gene expression of oral microbiota deposited on the titanium implants. In this study, we aimed to investigate the impact of different nanostructured surfaces on the biofilm in vivo.ResultsNanophase calcium phosphate were successfully deposited into or between the TiO2 nanotubes with a diameter of 70–90 nm. NT and NTN surfaces showed increased roughness than the MP surface. XPS spectra showed that the O 1s was mainly divided into two bands in MP and NT samples, including Ti-O and -OH, while the surface modification of TiO2 nanotube in NT accounted for the increased intensity of Ti-O with the reference to that in MP samples. After the deposition of calcium phosphate, two new elemental peaks of Ca and P can be identified from the XPS survey spectrum of NTN. Moreover, the O 1s of NTN sample could be differentiated into three peaks, while the new one represented the -PO band. The 16S rDNA sequencing results showed that NT and NTN had minimal impact on the diversity and community structure of oral microbiota. Metatranscriptomic sequencing revealed that differentially expressed genes (DEGs) mostly differed in the terms of the biological process and cellular component on different surfaces. Gene Ontology (GO) terms enrichment indicated that NTN down-regulate the genes associated in localization and locomotion. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that the DEGs were associated with microbial metabolism, protein synthesis and bacterial invasion of epithelial cells.ConclusionTiO2 nanotube and calcium phosphate-coated TiO2 nanotube despite improving the antimicrobial properties of implant surfaces, had unexpectedly minimal impact on the microbiome composition and diversity. Notably, nanostructured titanium surfaces could inhibit the bacterial migration and colonization, down-regulate the pathogen invasion pathways, and further destruct bacterial cellular membrane, all in all, conferred the bactericidal properties.


2021 ◽  
Vol 23 (1) ◽  
pp. 343
Author(s):  
Zhe Wang ◽  
Xiaoping Gou

Stomata regulate gas and water exchange between the plant and external atmosphere, which are vital for photosynthesis and transpiration. Stomata are also the natural entrance for pathogens invading into the apoplast. Therefore, stomata play an important role in plants against pathogens. The pattern recognition receptors (PRRs) locate in guard cells to perceive pathogen/microbe-associated molecular patterns (PAMPs) and trigger a series of plant innate immune responses, including rapid closure of stomata to limit bacterial invasion, which is termed stomatal immunity. Many PRRs involved in stomatal immunity are plasma membrane-located receptor-like protein kinases (RLKs). This review focuses on the current research progress of RLK-mediated signaling pathways involved in stomatal immunity, and discusses questions that need to be addressed in future research.


2021 ◽  
Author(s):  
Qingjie Li ◽  
Lianping Wang ◽  
Shuang Liu ◽  
Jingwen Xu ◽  
Zeyu Song ◽  
...  

Abstract AimsThis study was conducted to screen the type Ⅲ secretion system (T3SS) inhibitors of Salmonella enterica serovar Typhimurium (S. Typhimurium) from natural compounds. Through systemic analysis the pharmacological activity and action mechanism of candidate compounds in vivo and in vitro. Methods and resultsUsing an effector-β-lactamase fusion reporter system in S. Typhimurium, we discovered that quercitrin could block effector SipA translocation into eukaryotic host cell without affecting bacterial growth, and inhibit invasion or epithelial cells damage. Using β-galactosidase activity and Western blot assay, it was found that quercitrin significantly inhibits the expression of SPI-1 genes (hilA and sopA) and effectors (SipA and SipC). The animal experiment results indicated that quercitrin reduces mortality, pathological damages and colony colonization of infected mice. ConclusionsSmall-molecule inhibitor quercitrin directly inhibits the founction of T3SS in S. Typhimurium, and provids a potential alternative antimicrobial against Salmonella infection.Significance and impact of the studyNatural compounds have become valuable resources for antibacterials discovery due to their widely structures and biological activities. However, the potential targets and molecular action mechanisms of candidate compounds responsible for anti-infections remain elusive. The T3SS plays a crucial role in bacterial invasion and pathogenesis process in S. Typhimurium. Compared with traditional antibiotics, small molecular compounds can inhibit the T3SS of Salmonella and achieve the effect of anti-infection. They have less pressure on bacterial survival and are not easy to produce drug resistance. This provides strong evidence for development novel anti-virulence drugs against Salmonella infection.


2021 ◽  
Author(s):  
Xin You ◽  
René Kallies ◽  
Ingolf Kühn ◽  
Matthias Schmidt ◽  
Hauke Harms ◽  
...  

AbstractNonmotile microorganisms often enter new habitats by co-transport with motile microorganisms. Here, we report that also lytic phages can co-transport with hyphal-riding bacteria and facilitate bacterial colonization of a new habitat. This is comparable to the concept of biological invasions in macroecology. In analogy to invasion frameworks in plant and animal ecology, we tailored spatially organized, water-unsaturated model microcosms using hyphae of Pythium ultimum as invasion paths and flagellated soil-bacterium Pseudomonas putida KT2440 as carrier for co-transport of Escherichia virus T4. P. putida KT2440 efficiently dispersed along P. ultimum to new habitats and dispatched T4 phages across air gaps transporting ≈0.6 phages bacteria−1. No T4 displacement along hyphae was observed in the absence of carrier bacteria. If E. coli occupied the new habitat, T4 co-transport fueled the fitness of invading P. putida KT2440, while the absence of phage co-transport led to poor colonization followed by extinction. Our data emphasize the importance of hyphal transport of bacteria and associated phages in regulating fitness and composition of microbial populations in water-unsaturated systems. As such co-transport seems analogous to macroecological invasion processes, hyphosphere systems with motile bacteria and co-transported phages could be useful models for testing hypotheses in invasion ecology.


2021 ◽  
Vol 10 (24) ◽  
pp. 5823
Author(s):  
Ruka Nakasone ◽  
Mariko Ashina ◽  
Takumi Kido ◽  
Harunori Miyauchi ◽  
Masafumi Saito ◽  
...  

Neonatal sepsis is characterized by systemic bacterial invasion followed by a massive inflammatory response. At present, no therapeutic strategy has been found that significantly reduces the mortality of neonatal sepsis. We aimed to investigate the protective role of an initial low-dose septic challenge for the prevention of subsequent lethal sepsis in a mouse model. A stock cecal slurry (CS) solution was prepared from adult ceca. The LD83 (1.5 mg CS/g) was used for all animals. An initial challenge of normal saline (NS) or 0.5 mg CS/g (non-lethal dose) was administered at four days of age, then 1.5 mg CS/g was administered intraperitoneally at seven days of age (72 h post-initial challenge), and survival was monitored. Initial exposure to NS (n = 10) resulted in 90% mortality following exposure to the LD83 CS dose in contrast to an initial exposure to CS (n = 16), which significantly decreased mortality to 6% (p < 0.0001), reduced blood bacterial counts, attenuated inflammatory responses, and suppressed lipid mediators. Initial exposure to a non-lethal CS dose prior to exposure to a lethal CS dose significantly reduces sepsis mortality, a protective effect that might be mediated by modulating abnormal systemic inflammatory responses.


2021 ◽  
Author(s):  
Nawar Naseer ◽  
Renate Bauer ◽  
Jenna Zhang ◽  
Igor E. Brodsky ◽  
Isabella Rauch ◽  
...  

Salmonella enterica serovar Typhimurium is a gram-negative pathogen that causes diseases ranging from gastroenteritis to systemic infection and sepsis. Salmonella uses type III secretion systems (T3SSs) to inject effectors into host cells. While these effectors are necessary for bacterial invasion and intracellular survival, intracellular delivery of T3SS products also enables detection of Salmonella by cytosolic immune sensors. Upon detecting translocated Salmonella ligands, these sensors form multimeric complexes called inflammasomes, which activate caspases that lead to proinflammatory cytokine release and pyroptosis. In particular, the Salmonella T3SS needle, inner rod, and flagellin proteins activate the NAIP/NLRC4 inflammasome in murine intestinal epithelial cells (IECs), which leads to restriction of bacterial replication and extrusion of infected IECs into the intestinal lumen, thereby preventing systemic dissemination of Salmonella . While these processes are studied quite well in mice, the role of the NAIP/NLRC4 inflammasome in human IECs remains unknown. Unexpectedly, we found the NAIP/NLRC4 inflammasome is dispensable for early inflammasome responses to Salmonella in both human intestinal epithelial cell lines and organoids. Additionally, the NLRP3 inflammasome and the adaptor protein ASC are not required for inflammasome activation in Caco-2 cells. Instead, we observed a partial requirement for caspase-1, and a necessity for caspase-4 and GSDMD pore-forming activity in mediating inflammasome responses to Salmonella in Caco-2 cells. These findings suggest that unlike murine IECs, human IECs do not rely on NAIP/NLRC4, and also do not use NLRP3/ASC. Instead, they primarily use caspases-1 and -4 to mediate early inflammasome responses to SPI-1-expressing Salmonella .


2021 ◽  
Author(s):  
James T. Sorrentino ◽  
Gregory J. Golden ◽  
Claire Morris ◽  
Chelsea Painter ◽  
Victor Nizet ◽  
...  

Vascular dysfunction and organ failure are two distinct, albeit highly interconnected clinical outcomes linked to morbidity and mortality in human sepsis. The mechanisms driving vascular and parenchymal damage are dynamic and display significant molecular crosstalk between organs and tissues. Therefore, assessing their individual contribution to disease progression is technically challenging. Here, we hypothesize that dysregulated vascular responses predispose the organism to organ failure. To address this hypothesis, we have evaluated four major organs in a murine model of S. aureus sepsis by combining in vivo labeling of the endothelial proteome, data-independent acquisition (DIA) mass spectrometry, and an integrative computational pipeline. The data reveal, with unprecedented depth and throughput, that a septic insult evokes organ-specific proteome responses that are highly compartmentalized, synchronously coordinated, and significantly correlated with the progression of the disease. Vascular proteome changes were found to precede bacterial invasion and leukocyte infiltration into the organs, as well as to precede changes in various well-established cellular and biochemical correlates of systemic coagulopathy and tissue dysfunction. Importantly, our data suggests a potential role for the vascular proteome as a determinant of the susceptibility of the organs to undergo failure during sepsis.


2021 ◽  
Vol 2021 ◽  
pp. 1-28
Author(s):  
Wanchen Ning ◽  
Yihong Ma ◽  
Simin Li ◽  
Xin Wang ◽  
Hongying Pan ◽  
...  

Objective. This study investigated the nature of shared transcriptomic alterations in PBMs from periodontitis and atherosclerosis to unravel molecular mechanisms underpinning their association. Methods. Gene expression data from PBMs from patients with periodontitis and those with atherosclerosis were each downloaded from the GEO database. Differentially expressed genes (DEGs) in periodontitis and atherosclerosis were identified through differential gene expression analysis. The disease-related known genes related to periodontitis and atherosclerosis each were downloaded from the DisGeNET database. A Venn diagram was constructed to identify crosstalk genes from four categories: DEGs expressed in periodontitis, periodontitis-related known genes, DEGs expressed in atherosclerosis, and atherosclerosis-related known genes. A weighted gene coexpression network analysis (WGCNA) was performed to identify significant coexpression modules, and then, coexpressed gene interaction networks belonging to each significant module were constructed to identify the core crosstalk genes. Results. Functional enrichment analysis of significant modules obtained by WGCNA analysis showed that several pathways might play the critical crosstalk role in linking both diseases, including bacterial invasion of epithelial cells, platelet activation, and Mitogen-Activated Protein Kinases (MAPK) signaling. By constructing the gene interaction network of significant modules, the core crosstalk genes in each module were identified and included: for GSE23746 dataset, RASGRP2 in the blue module and VAMP7 and SNX3 in the green module, as well as HMGB1 and SUMO1 in the turquoise module were identified; for GSE61490 dataset, SEC61G, PSMB2, SELPLG, and FIBP in the turquoise module were identified. Conclusion. Exploration of available transcriptomic datasets revealed core crosstalk genes (RASGRP2, VAMP7, SNX3, HMGB1, SUMO1, SEC61G, PSMB2, SELPLG, and FIBP) and significant pathways (bacterial invasion of epithelial cells, platelet activation, and MAPK signaling) as top candidate molecular linkage mechanisms between atherosclerosis and periodontitis.


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