A Low-Molecular-Weight Alginate Oligosaccharide Disrupts Pseudomonal Microcolony Formation and Enhances Antibiotic Effectiveness

Alginate oligosaccharide attenuates α2,6-sialylation modification to inhibit prostate cancer cell growth via the Hippo/YAP pathway

Chitosan oligosaccharides have been reported to inhibit various tumors. However, the water-soluble marine plant oligosaccharide alginate oligosaccharide (AOS) has only rarely been reported to have anti-cancer effects. Moreover, the inhibitory effect of AOS on prostate cancer and the underlying molecular mechanism remain unknown. This study shows that AOS inhibited cell growth, which was consistent with the attenuation of α2,6-sialylation modification. Furthermore, AOS inhibited ST6Gal-1 promoter activity and thus affected transcriptional processes. In addition, AOS could activate the Hippo/YAP pathway and block the recruitment of both the coactivator YAP and c-Jun. Furthermore, YAP interacted with the transcription factor c-Jun and regulated the transcriptional activity of the downstream target ST6Gal-1 gene. Consistent with in vitro data, AOS suppressed the tumorigenicity of prostate cancer cells via the Hippo/YAP pathway in vivo. In summary, these data indicate that AOS slows the proliferation of prostate cancer and provides a basis for the healthy function of kelp in traditional cognition.

A glycopolymer improves vascoelasticity and mucociliary transport of abnormal cystic fibrosis mucus

Cystic fibrosis (CF) is characterized by increased mucus viscosity and delayed mucociliary clearance that contributes to progressive decline of lung function. Mucus in the respiratory and GI tract is excessively adhesive in the presence of airway dehydration and excess extracellular Ca2+ upon mucin release, promoting hyperviscous, densely packed mucins characteristic of CF. Therapies that target mucins directly through ionic interactions remain unexploited. Here we show that poly (acetyl, arginyl) glucosamine (PAAG), a polycationic biopolymer suitable for human use, interacts directly with mucins in a Ca2+-sensitive manner to reduce CF mucus viscoelasticity and improve its transport. Notably, PAAG induced a linear structure of purified MUC5B and altered its sedimentation profile and viscosity, indicative of proper mucin expansion. In vivo, PAAG nebulization improved mucociliary transport in CF rats with delayed mucus clearance, and cleared mucus plugging in CF ferrets. This study demonstrates the potential use of a synthetic glycopolymer PAAG as a molecular agent that could benefit patients with a broad array of mucus diseases.

Characterization of a new endo-type polysaccharide lyase (PL) family 6 alginate lyase with cold-adapted and metal ions-resisted property

Alginate lyase played an important role in brown algae degradation, and its enzymatic degradation products showed various biological activities. Although many alginate lyases have been characterized, the enzymes with special characterizations are still rather rare. In this study, a new alginate lyase gene, tsaly6A, has been cloned from marine bacterium Thalassomonas sp. LD5, and expressed in Escherichia coli. The deduced alginate lyase, TsAly6A, belonged to the polysaccharide lyase (PL) family 6 and showed the highest amino acid identity (63%) with an exo-type oligoalginate lyase AlyGC. However, this study showed that TsAly6A was an endo-type enzyme yielding alginate trisaccharides (64.5%) as the main products. Compared with other alginate lyases, TsAly6A showed high trisaccharide-yielding levels. Meanwhile, TsAly6A showed the specific activity of 15,960 U/μmol at its optimal pH (pH 8.0) and temperature (35 °C). In addition, TsAly6A was a cold-adapted, salt-activated and metal ions-resisted alginate lyase, which will enable it to perform high activity in the solution containing various ions. Its cold-adaptation, metal ions-tolerance and high trisaccharides yields make TsAly6A an excellent candidate for industrial applications.

The Therapeutic Pipeline for Pseudomonas aeruginosa Infections

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen, designated by the World Health Organization as a critical priority for development of new therapeutics due to high levels of intrinsic and acquired antibiotic resistance. Other challenges include its versatility (it can persist in the environment and most strains are capable of causing disease in compromised hosts), robust efflux mechanisms that limit drug penetration, and the propensity to form antimicrobial-tolerant biofilms. Novel therapeutics in development to prevent or treat P. aeruginosa infections include vaccines, biologics such as antimicrobial peptides and therapeutic antibodies, virulence inhibitors, antimicrobials with novel targets, antibody-drug conjugates, resistance inhibitor-antibiotic or antibiotic-potentiator combinations, and bacteriophages or phage-derived lysins.

Highlights from the 2017 North American Cystic Fibrosis Conference

The 31st annual North American Cystic Fibrosis Conference (NACFC) was held in Indianapolis, IN on November 2-4, 2017. Abstracts of presentations from the conference were published in a supplement to Pediatric Pulmonology [2017; Pediatr Pulmonol Suppl. 52: S1-S776]. The current review summarizes several major topic areas addressed at the conference: the pathophysiology and basic science of cystic fibrosis (CF) lung disease, clinical trials, clinical management issues, and quality improvement (QI). In this review, we describe emerging concepts in several areas of CF research and care.

Targeted disruption of the extracellular polymeric network of Pseudomonas aeruginosa biofilms by alginate oligosaccharides

Acquisition of a mucoid phenotype by Pseudomonas sp. in the lungs of cystic fibrosis (CF) patients, with subsequent over-production of extracellular polymeric substance (EPS), plays an important role in mediating the persistence of multi-drug resistant (MDR) infections. The ability of a low molecular weight (Mn = 3200 g mol⁻¹) alginate oligomer (OligoG CF-5/20) to modify biofilm structure of mucoid Pseudomonas aeruginosa (NH57388A) was studied in vitro using scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) with Texas Red (TxRd®)-labelled OligoG and EPS histochemical staining. Structural changes in treated biofilms were quantified using COMSTAT image-analysis software of CLSM z-stack images, and nanoparticle diffusion. Interactions between the oligomers, Ca²⁺ and DNA were studied using molecular dynamics (MD) simulations, Fourier transform infrared spectroscopy (FTIR) and isothermal titration calorimetry (ITC). Imaging demonstrated that OligoG treatment (≥0.5%) inhibited biofilm formation, revealing a significant reduction in both biomass and biofilm height (P < 0.05). TxRd®-labelled oligomers readily diffused into established (24 h) biofilms. OligoG treatment (≥2%) induced alterations in the EPS of established biofilms; significantly reducing the structural quantities of EPS polysaccharides, and extracellular (e)DNA (P < 0.05) with a corresponding increase in nanoparticle diffusion (P < 0.05) and antibiotic efficacy against established biofilms. ITC demonstrated an absence of rapid complex formation between DNA and OligoG and confirmed the interactions of OligoG with Ca²⁺ evident in FTIR and MD modelling. The ability of OligoG to diffuse into biofilms, potentiate antibiotic activity, disrupt DNA-Ca²⁺-DNA bridges and biofilm EPS matrix highlights its potential for the treatment of biofilm-related infections.

Small carbohydrate molecules derived from marine algae show potential for inhibiting biofilm formation in multi-drug resistant infections. A research team led by Lydia Powell at Cardiff University, UK, investigated the action of carbohydrates called alginate oligosaccharides, composed of a small number of linked sugar molecules. The oligosaccharides modified and disrupted the structure of cultured biofilms of Pseudomonas aeruginosa, the cause of many serious drug resistant infections. This effect significantly inhibited the formation and maintenance of the biofilm state, which is known to be a crucial factor allowing the bacteria to resist drug treatment. Antibiotics proved more effective following the oligosaccharide intervention. The researchers uncovered key molecular details involved in the ability of the oligosaccharides to diffuse into and disrupt biofilms. The therapeutic potential of these small carbohydrates is currently being investigated in clinical trials.