Effects of heparosan and heparin on the adhesion and biofilm formation of several bacteria in vitro

Effects of dietary D-lactate levels on rumen fermentation, microflora and metabolomics of beef cattle

Introduction

Excessive intake of lactate caused by improper use of silage in animal husbandry has adverse effects on rumen fermentation, such as rumen acidosis. The speed of absorption and metabolism of D-lactate in rumen epithelial cells was slower than that of L-lactate, making D-lactate more prone to accumulate and induce rumen acidosis. Therefore, this study was conducted to explore the effects of dietary D-lactate levels on rumen fermentation of beef cattle and its mechanism in an in vitro system.

Methods

This experiment was adopted in single-factor random trial design, with 5 days for adaptation and 3 days for sample collection. Three treatments (n = 8/treatment) were used: (1) D-LA (0.3%), basal fermentation substrate with 0.3% (dry matter, DM basis) D-lactate; (2) D-LA (0.75%), basal fermentation substrate with 0.75% (DM basis) D-lactate; and (3) D-LA (1.2%), basal fermentation substrate with 1.2% (DM basis) D-lactate.

Results

With the dietary D-lactate levels increased, the daily production of total gas, hydrogen and methane, as well as the ruminal concentrations of acetate, propionate, butyrate, isobutyrate, valerate, isovalerate, total volatile fatty acid and D-lactate increased (p < 0.05), but the ruminal pH and acetate/propionate ratios decreased (p < 0.05). Principle coordinate analysis based on Bray-Curtis distance showed that increasing dietary D-lactate levels could significantly affect the structure of rumen bacterial community (p < 0.05), but had no significant effect on the structure of rumen eukaryotic community (p > 0.05). NK4A214_group, Ruminococcus_gauvreauii_group, Eubacterium_oxidoreducens_group, Escherichia-Shigella, Marvinbryantia and Entodinium were enriched in D-LA (1.2%) group (p < 0.05), as well as WCHB1-41, vadinBE97, Clostridium_sensu_stricto_1, Anaeroplasma and Ruminococcus were enriched in D-LA (0.3%) group (p < 0.05). Changes in the composition of ruminal microorganisms affected rumen metabolism, mainly focus on the biosynthesis of glycosaminoglycans (p < 0.05).

Discussion

Overall, feeding whole-plant corn silage with high D-lactate content could not induce rumen acidosis, and the metabolization of dietary D-lactate into volatile fatty acids increased the energy supply of beef cattle. However, it also increased the ruminal CH4 emissions and the relative abundance of opportunistic pathogen Escherichia-Shigella in beef cattle. The relative abundance of Verrucomicrobiota and Escherichia-Shigella may be influenced by glycosaminoglycans, reflecting the interaction between rumen microorganisms and metabolites.

Inhibition of bacterial swimming by heparin binding of flagellin FliC from Escherichia coli strain Nissle 1917

Escherichia coli Nissle1917 (EcN) is a non-pathogenic probiotic strain widely used to maintain gut health, treat gastrointestinal disorders, and modulate the gut microbiome due to its anti-inflammatory and competitive exclusion effects against pathogenic bacteria. Heparin, abundant on intestinal mucosal surfaces, is a highly sulfated glycosaminoglycan primarily produced by mast cells. Currently, the interaction between EcN surface protein and heparin has remained elusive. In this study, the flagellin FliC responsible for EcN's movement was separated and characterized as a heparin binding protein by mass spectrometry (MS) analysis. The recombinant FliC protein, expressed by plasmid pET28a( +)-fliC, was further prepared to confirm the interaction between FliC and heparin. The results showed that heparin-Sepharose's ability to bind FliC was 48-fold higher than its ability to bind the negative control, bovine serum albumin (BSA). Neither the knockout of gene fliC nor the addition of heparin affects the growth of EcN, but both significantly inhibit the swimming of EcN. Adding 10 mg/ml heparin reduced the swimming diameter of the wild type and the complemented strain to 29-41% of the original, but that did not affect the swimming ability of the knockout strains. These results demonstrate that heparin interacts with EcN flagellin FliC and inhibits bacteria swimming. Exploring this interaction could improve our understanding of the relationship between hosts and microorganisms and provide a potential basis for disease treatment.

In vitro fermentation of heparin by the human gut microbiota: Changes in the microbiota community and metabolic functions

Levels of its utilization suggest that the host glycosaminoglycan heparin is an important carbohydrate in the human gut microbiota. However, the interaction between heparin and the gut microbiota is not well understood. In this study, an in vitro fermentation system combined with microbiome and metabolome technologies was used to study the interaction between heparin and the gut microbiota. Interestingly, we found that heparin can be used by the gut microbiota, which produce large amounts of short chain fatty acids leading to a decrease in pH. In addition, the addition of heparin increased the relative abundance of Bacteroides and Bifidobacterium and decreased the relative abundance of Escherichia-Shigella. Correlation analysis of the microbiome and metabolome revealed that the catabolism of heparin was accompanied by the biosynthesis of bile acids and tryptophan metabolism. Overall, this study provides new evidence on the role of heparin as a stable carbon source for the gut microbiota and forms a strong basis for the use of heparin to condition the gut microbiota.

Responses of the gut microbiota and metabolite profiles to sulfated polysaccharides from sea cucumber in humanized microbiota mice

Sea cucumber Stichopus japonicus has been consumed as functional food traditionally in Asia, and its sulfated polysaccharide (SCSPsj) demonstrates health-promoting effects in rodents which are related to the regulation of the gut microbiota. However, little is known about the response of the human gut microbiota to SCSPsj. Therefore, the present study aimed to study the response of the donor microbiota to SCSPsj in vivo through a humanized microbiota mice model, which was constructed by antibiotic treatment combined with fecal microbiota transplant. The results revealed that the SCSPsj supplement could positively interact with the specific donor microbiota. It could significantly regulate the gut microbiota community, especially the abundance of Lactobacillus. In addition, SCSPsj could modulate the metabolites in serum and cecal contents of mice, including short-chain fatty acids (SCFAs) and lactic acid, and the changes of some bioactive metabolites were associated with the gut microbiota enriched by SCSPsj. Furthermore, in vitro experiments demonstrated that the Lactobacillus strains isolated could not be proliferated directly by SCSPsj, but SCSPsj significantly promoted biofilm formation and mucus binding of Lactobacillus spp., which contributed to the enrichment of Lactobacillus in vivo. The present study could provide insight into the application of SCSPsj as microbiota-directed food.

Human Fibrinogen Inhibits Amyloid Assembly of Most Phenol-Soluble Modulins from Staphylococcus aureus

Functional amyloids are highly organized protein/peptide structures that inter alia promote biofilm formation in different bacteria. One such example is provided by a family of 20-45 residue-long peptides called phenol-soluble modulins (PSMs) from Staphylococcus aureus. External components such as eukaryotic host proteins, which alter self-assembly of bacterial amyloids, can affect the biofilm matrix. Here, we studied the effect of the highly prevalent human plasma protein fibrinogen (Fg) on fibrillation of PSMs. Fg inhibits or suppresses fibrillation of most PSMs tested (PSMα1, PSMβ1, and PSMβ2) except for PSMα3, whose already rapid aggregation is accelerated even further by Fg but leads to amorphous β-rich aggregates rather than fibrils. Fg also induces PSMβ2 to form amorphous aggregates and diverts PSMα1 into off-pathway oligomers which consist of both Fg and PSMα1 and cannot seed fibrillation. Peptide arrays showed that Fg bound to the N-terminus of PSMα1, while it bound to the entire length of PSMα3 (except the C terminus) and to the C-termini of PSMβ1 and PSMβ2. The latter peptides are all positively charged, while Fg is negatively charged at physiological pH. The positive charges complement Fg's net negative charge of -7.6 at pH 7.4. Fg's ability to inhibit PSM fibrillation reveals a potential host-defense mechanism to prevent bacterial biofilm growth and infections in the human body.

Does the Reprocessing of Endoscopes Have to Take Place Immediately after Pre-Cleaning? A First Evaluation

Background/Aims

The recommendations on the time interval between pre-cleaning and reprocessing of endoscopes differ in international guidelines, with a low level of evidence. The aim of this study was to investigate the influence of postponing reprocessing on the reprocessing quality after pre-cleaning the flexible endoscopes.

Methods

We reprocessed 124 standardized test tubes simulating endoscope channels after soiling and contamination and determined the reprocessing performance. In addition, we examined contaminated gastroscopes, colonoscopes, and bronchoscopes. The duration of interim storage after pre-cleaning was 16 h for 100 test tubes and up to 24 h for 18 endoscopes. We determined the residual protein content and germ load as markers for cleaning and disinfection performance. In addition, we determined biofilm formation by photometry of crystal violet staining.

Results

All test tubes and flexible endoscopes showed residual protein content and germ load significantly below legally prescribed threshold values, independent of the interval between pre-cleaning and reprocessing.

Conclusions

Our findings indicate that flexible endoscopes could be stored overnight after pre-cleaning without any influence on the quality of reprocessing. While ensuring patient safety, this could simplify logistical processes and enable cost savings.

Heparin stimulates biofilm formation of Escherichia coli strain Nissle 1917

OBJECTIVES

Escherichia coli strain Nissle 1917 (EcN), a gut probiotic competing with pathogenic bacteria, has been used to attenuate various intestinal dysfunctions. Heparin is a sulfated glycosaminoglycan enriched in the human and animal intestinal mucosa, which has a close connection with bacterial biofilm formation. However, the characteristics of heparin affecting bacterial biofilm formation remain obscure. In this study, we investigated the influence of heparin and its derivatives on EcN biofilm formation.

RESULTS

Here, we found that heparin stimulated EcN biofilm formation in a dose-dependent manner. With the addition of native heparin, the EcN biofilm formation increased 6.9- to 10.8-fold than that without heparin, and was 1.4-, 3.1-, 3.0-, and 3.8-fold higher than that of N-desulfated heparin (N-DS), 2-O-desulfated heparin (2-O-DS), 6-O-desulfated heparin (6-O-DS), and N-/2-O-/6-O-desulfated heparin (N-/2-O-/6-O-DS), respectively. Depolymerization of heparin produced chain-shortened heparin fragments with decreased molecular weight. The depolymerized heparins did not stimulate EcN biofilm formation. The OD570 value of EcN biofilm with the addition of chain-shortened heparin fragments was 8.7-fold lower than that of the native heparin. Furthermore, the biofilm formation of Salmonella enterica serovar Typhimurium was also investigated with the addition of heparin derivatives, and the results were consistent with that of EcN biofilm formation.

CONCLUSIONS

We conclude that heparin stimulated EcN biofilm formation. Both the sulfation and chain-length of heparin contributed to the enhancement of EcN biofilm formation. This study increases the understanding of how heparin affects biofilm formation, indicating the potential role of heparin in promoting intestinal colonization of probiotics that antagonize pathogen infections.

Cell surface processing of the P1 adhesin of Mycoplasma pneumoniae identifies novel domains that bind host molecules

Mycoplasma pneumoniae is a genome reduced pathogen and causative agent of community acquired pneumonia. The major cellular adhesin, P1, localises to the tip of the attachment organelle forming a complex with P40 and P90, two cleavage fragments derived by processing Mpn142, and other molecules with adhesive and mobility functions. LC-MS/MS analysis of M. pneumoniae M129 proteins derived from whole cell lysates and eluents from affinity matrices coupled with chemically diverse host molecules identified 22 proteoforms of P1. Terminomics was used to characterise 17 cleavage events many of which were independently verified by the identification of semi-tryptic peptides in our proteome studies and by immunoblotting. One cleavage event released ¹⁵⁹⁷TSAAKPGAPRPPVPPKPGAPKPPVQPPKKPA¹⁶²⁷ from the C-terminus of P1 and this peptide was shown to bind to a range of host molecules. A smaller synthetic peptide comprising the C-terminal 15 amino acids, ¹⁶¹³PGAPKPPVQPPKKPA¹⁶²⁷, selectively bound cytoskeletal intermediate filament proteins cytokeratin 7, cytokeratin 8, cytokeratin 18, and vimentin from a native A549 cell lysate. Collectively, our data suggests that ectodomain shedding occurs on the surface of M. pneumoniae where it may alter the functional diversity of P1, Mpn142 and other surface proteins such as elongation factor Tu via a mechanism similar to that described in Mycoplasma hyopneumoniae.

Current insights into the mechanisms and management of infection stones

Infection stones are complex aggregates of crystals amalgamated in an organic matrix that are strictly associated with urinary tract infections. The management of patients who form infection stones is challenging owing to the complexity of the calculi and high recurrence rates. The formation of infection stones is a multifactorial process that can be driven by urine chemistry, the urine microenvironment, the presence of modulator substances in urine, associations with bacteria, and the development of biofilms. Despite decades of investigation, the mechanisms of infection stone formation are still poorly understood. A mechanistic understanding of the formation and growth of infection stones - including the role of organics in the stone matrix, microorganisms, and biofilms in stone formation and their effect on stone characteristics - and the medical implications of these insights might be crucial for the development of improved treatments. Tools and approaches used in various disciplines (for example, engineering, chemistry, mineralogy, and microbiology) can be applied to further understand the microorganism-mineral interactions that lead to infection stone formation. Thus, the use of integrated multidisciplinary approaches is imperative to improve the diagnosis, prevention, and treatment of infection stones.

Therapeutic strategies to target microbial protein-glycosaminoglycan interactions

Glycans are involved in a plethora of human pathologies including infectious diseases. Especially, glycosaminoglycans (GAGs), like heparan sulfate and chondroitin sulfate, have been found to be involved in different crucial stages of microbial invasion. Here, we review various therapeutic approaches, which target the interface of host GAGs and microbial proteins and discuss their limitations and challenges for drug development.

Borrelia burgdorferi glycosaminoglycan-binding proteins: a potential target for new therapeutics against Lyme disease

The spirochete bacterium Borrelia burgdorferi sensu lato is the causative agent of Lyme disease, the most common vector-borne disease in Europe and the United States. The spirochetes can be transmitted to humans via ticks, and then spread to different tissues, leading to arthritis, carditis and neuroborreliosis. Although antibiotics have commonly been used to treat infected individuals, some treated patients do not respond to antibiotics and experience persistent, long-term arthritis. Thus, there is a need to investigate alternative therapeutics against Lyme disease. The spirochete bacterium colonization is partly attributed to the binding of the bacterial outer-surface proteins to the glycosaminoglycan (GAG) chains of host proteoglycans. Blocking the binding of these proteins to GAGs is a potential strategy to prevent infection. In this review, we have summarized the recent reports of B. burgdorferi sensu lato GAG-binding proteins and discussed the potential use of synthetic and semi-synthetic compounds, including GAG analogues, to block pathogen interaction with GAGs. Such information should motivate the discovery and development of novel GAG analogues as new therapeutics for Lyme disease. New therapeutic approaches should eventually reduce the burden of Lyme disease and improve human health.

Hyaluronan 35kDa treatment protects mice from Citrobacter rodentium infection and induces epithelial tight junction protein ZO-1 in vivo

Maintaining a healthy intestinal barrier, the primary physical barrier between intestinal microbiota and the underlying lamina propria, is critical for optimal health. Epithelial integrity is essential for the prevention of the entrance of luminal contents, such as bacteria and their products, through the large intestinal barrier. In this study, we investigated the protective functions of biosynthetic, specific sized, hyaluronan around 35kDa (HA35) on intestinal epithelium in healthy mice, as well as mice infected Citrobacter rodentium, an established model that mimics infection with a serious human pathogen, enteropathogenic E. coli (EPEC). Our results reveal that treatment with HA35 protects mice from Citrobacter infection and enhances the epithelial barrier function. In particular, we have found that HA35 induces the expression of tight junction protein zonula occludens (ZO)-1 in both healthy and Citrobacter infected mice, as demonstrated by immunoflurorescence and Western blot analyses. Furthermore, we determined that HA35 treatment enhances ZO-1 expression and reduces intestinal permeability at the early stages of dextran sulfate sodium (DSS)-induced colitis in mice. Together, our data demonstrate that the expression and functionality of tight junctions, are increased by HA35 treatment, suggesting a novel mechanism for the protection from Citrobacter infection.

Surface Proteoglycans as Mediators in Bacterial Pathogens Infections

Infectious diseases remain an important global health problem. The interaction of a wide range of pathogen bacteria with host cells from many different tissues is frequently mediated by proteoglycans. These compounds are ubiquitous complex molecules which are not only involved in adherence and colonization, but can also participate in other steps of pathogenesis. To overcome the problem of microbial resistance to antibiotics new therapeutic agents could be developed based on the characteristics of the interaction of pathogens with proteoglycans.