Adhesion of human pathogenic bacteria to endothelial cells is facilitated by fibronectin interaction

The effects and mechanisms of aqueous Persicaria capitata extract on uropathogenic Escherichia coli adhesion

BACKGROUND

Urinary tract infections (UTIs) in humans are common, with uropathogenic Escherichia coli (UPEC) being the primary pathogen. The adhesive capabilities of UPEC are a substantial pathogenicity factor. Due to limitations of first-line antibiotics, Persicaria capitata (Buch.-Ham. ex D. Don) H. Gross, a traditional Chinese medicinal plant, is frequently used to treat various urological disorders. However, its mechanism regarding bacterial adhesion, remain unclear.

PURPOSE

To investigate the effects and mechanisms of action of aqueous P. capitata extracts (PCE) on UPEC adhesion in T24 cells and rat models.

METHODS

Broth microdilution and growth experiments were used to explore the direct antibacterial effects of PCE on UPEC. Additionally, motility assays were conducted. Different microscopy methods were used to further examine the mechanisms of action. Transcriptomic analysis and RT-qPCR were used to explore mechanisms on a molecular level. Relevant molecules were assessed using western blotting and immunohistochemistry.

RESULTS

PCE modulated UPEC motility by disrupting the fimbriae and flagella. UPEC pathways, including those essential for constructing fimbriae and flagella, and bacterial motility, were affected. PCE reduced UPEC adhesion and invasion of T24 cells, altering the protein expression of adhesion-related molecules, by modulating the secretion of extracellular vesicles (EVs). It improved blood and urine parameters, reduced inflammatory markers, and ameliorated pathological changes in the kidneys and bladder of rats. Furthermore, the expression of adhesion-related molecules in bladder tissues decreased in the UTI rat model.

CONCLUSIONS

This study provides new insights into the mechanisms of herbal medicines in treating UTIs.

Bactericidal Effect of a Novel Phage Endolysin Targeting Multi-Drug-Resistant Acinetobacter baumannii

BACKGROUND/OBJECTIVES

Infections with antibiotic-resistant Gram-negative pathogens represent a major global threat to public health. Acinetobacter baumannii is a highly important nosocomial pathogen causing severe and life-threatening infections, like pneumonia, wound infections, or sepsis. It is often resistant even against last-resort antibiotics, such as carbapenems, and can persist in healthcare settings. Artilysin®s are a novel class of endolysins targeted against multidrug-resistant bacteria.

METHODS

Antibacterial activity of Art-Top3 was determined by broth microdilution, in vitro assays and in the Galleria mellonella infection model. The toxicity of Art-Top3 on red blood cells, endothelial and epithelial cells was analyzed using the MTT assay.

RESULTS

Here, we report on a new Artilysin® Art-Top3 that is active against A. baumannii and led to a 105-fold reduction in viable A. baumannii after five minutes of exposure. Art-Top3 showed activity against A. baumannii biofilms in static and dynamic experimental infection models. Furthermore, upon infection with carbapenem-resistant A. baumannii patient isolates, Art-Top3 was able to rescue human primary cells in vitro and larvae of Galleria mellonella in an in vivo infection model. Art-Top3 did not lyse human red blood cells and showed activity in human serum, indicating a low toxicity and high stability of Art-Top3 in vitro.

CONCLUSION

Our findings collectively establish that Art-Top3 might be a candidate for novel therapeutic strategies of infections caused by multidrug-resistant A. baumannii pathogens.

Comparison of transcriptomic profiles between intracellular and extracellular Bartonella henselae

The Bartonella genus of bacteria encompasses ubiquitous species, some of which are pathogenic in humans and animals. Bartonella henselae, the causative agent of Cat Scratch disease, is responsible for a large portion of human Bartonella infections. These bacteria can grow outside of cells, replicate in erythrocytes and invade endothelial and monocytic cells. We have previously reported reduced antibiotic susceptibility of intracellular Bartonella. In this study we performed comparative transcriptomic analyses between the extracellular and intracellular B. henselae phenotypes. Overall, specific genes involved in invasion, virulence, extracellular adhesion of type 4 secretion system were downregulated following intracellular invasion of B. henselae. Downregulation included BadA, a well-characterized adhesin molecule, of critical importance for cell invasion. These studies demonstrate the ability to purify Bartonella RNA from infected cells and offer a repository of gene expression data for future research. The development of novel therapeutics will benefit from the ability to determine target expression by Bartonella in relevant microenvironments.

μREACT: A microfluidic system for rapid evaluation of trans-kingdom interactions

Trans-kingdom interactions between cells play pivotal roles in shaping intricate ecological and biological networks. However, our grasp of these interactions remains incomplete. Specifically, the vast phylogenetic spectrum of microorganisms capable of interacting with a given host cell type remains obscure, primarily due to the absence of efficient, high-throughput, single-cell resolution systems that can rapidly decipher these interactions. Here, we introduce μREACT (Microfluidic system for Rapid Evaluation of bacterial Adherence and Communication in Trans-kingdom interactions), a microfluidic system designed to analyze interkingdom interactions. μREACT not only unveiled both recognized and previously unknown interactions but also enabled their detailed characterization. The system features the use of microfluidic dielectrophoretic separation of bacteria that adhere to host cells at single-cell (digital) resolution, and enabled the sorting of 107 adherent microorganisms per hour, representing a comparable throughput to conventional flow cytometry systems, but without requiring any labeling. The analysis of soil microbial samples using μREACT revealed several bacterial species previously known to have high adherence to mammalian host cells, as well as new interactions involving strains that displayed hallmarks of emerging endosymbiosis. Taken together, μREACT serves as a formidable tool for identifying and characterizing webs of interkingdom interactions. Its implications extend beyond discovery of such interactions, where it has the potential to provide new insights into fundamental mechanisms driving ecosystem dynamics and biological processes.

From probiotic chassis to modification strategies, control and improvement of genetically engineered probiotics for inflammatory bowel disease

With the rising morbidity of inflammatory bowel disease (IBD) year by year, conventional therapeutic drugs with systemic side effects are no longer able to meet the requirements of patients. Probiotics can improve gut microbiota, enhance intestinal barrier function, and regulate mucosal immunity, making them a potential complementary or alternative therapy for IBD. To compensate for the low potency of probiotics, genetic engineering technology has been widely used to improve their therapeutic function. In this review, we systematically summarize the genetically engineered probiotics used for IBD treatment, including probiotic chassis, genetic modification strategies, methods for controlling probiotics, and means of improving efficacy. Finally, we provide prospects on how genetically engineered probiotics can be extended to clinical applications.

Analyzing the interaction of Helicobacter pylori GAPDH with host molecules and hemin: Inhibition of hemin binding

Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is a moonlighting enzyme. Apart from its primary role in the glycolytic pathway, in many bacterial species it is found in the extracellular milieu and also on the bacterial surface. Positioning on the bacterial surface allows the GAPDH molecule to interact with many host molecules such as plasminogen, fibrinogen, fibronectin, laminin and mucin etc. This facilitates the bacterial colonization of the host. Helicobacter pylori is a major human pathogen that causes a number of gastrointestinal infections and is the main cause of gastric cancer. The binding analysis of H. pylori GAPDH (HpGAPDH) with host molecules has not been carried out. Hence, we studied the interaction of HpGAPDH with holo-transferrin, lactoferrin, haemoglobin, fibrinogen, fibronectin, catalase, plasminogen and mucin using biolayer interferometry. Highest and lowest binding affinity was observed with lactoferrin (4.83 ± 0.70 × 10-9 M) and holo-transferrin (4.27 ± 2.39 × 10-5 M). Previous studies established GAPDH as a heme chaperone involved in intracellular heme trafficking and delivery to downstream target proteins. Therefore, to get insights into heme binding, the interaction between HpGAPDH and hemin was analyzed. Hemin binds to HpGAPDH with an affinity of 2.10 μM while the hemin bound HpGAPDH does not exhibit activity. This suggests that hemin most likely binds at the active site of HpGAPDH, prohibiting substrate binding. Blind docking of hemin with HpGAPDH also supports positioning of hemin at the active site. Metal ions were found to inhibit the activity of HpGAPDH, suggesting that it also possibly occupies the substrate binding site. Furthermore, with metal-bound HpGAPDH, hemin binding was not observed, suggesting metal ions act as an inhibitor of hemin binding. Since GAPDH has been identified as a heme chaperone, it will be interesting to analyse the biological consequences of inhibition of heme binding to GAPDH by metal ions.