Performance assessment of an injectable hyaluronic acid/polylactic acid complex hydrogel with enhanced biological properties as a dermal filler

Injectable hyaluronic acid (HA) hydrogel plays an important role in dermal filling. However, conventional HA dermal fillers mostly lack bio-functional diversity and frequently cause adverse reactions because of the chemical stiffness of highly modified degree and crosslinker residues. In this study, polylactic acid (PLA) was embedded into HA hydrogel as a bioactive substance and 1,4-butanediol diglycidyl ether was used as a crosslinker to prepare the HA/PLA composite hydrogel with enhanced biocompatibility and biological performance. We aimed to investigate the properties of HA/PLA composite hydrogels as dermal fillers by assessing the rheological properties, surface microstructure, enzymolysis stability, swelling ratio, degradation rate, cytotoxicity, and anti-wrinkle effect on photo-aged skin. The results showed that the stability and stiffness of the composite hydrogel decreased with an increasing amount of PLA, while the in vivo safety of the HA/PLA hydrogel was enhanced, showing no adverse reactions such as edema, redness, or swelling. Moreover, the composite hydrogel with 2 wt% PLA exhibited excellent anti-wrinkle effects, showing the highest collagen production. Thus, the PLA-embedded HA composite hydrogel showed potential as a dermal filler with high safety, easy injectability, and excellent anti-wrinkle effects.

Genome degradation promotes Salmonella pathoadaptation by remodeling fimbriae-mediated proinflammatory response

Understanding changes in pathogen behavior (e.g. increased virulence, a shift in transmission channel) is critical for the public health management of emerging infectious diseases. Genome degradation via gene depletion or inactivation is recognized as a pathoadaptive feature of the pathogen evolving with the host. However, little is known about the exact role of genome degradation in affecting pathogenic behavior, and the underlying molecular detail has yet to be examined. Using large-scale global avian-restricted Salmonella genomes spanning more than a century, we projected the genetic diversity of Salmonella Pullorum (bvSP) by showing increasingly antimicrobial-resistant ST92 prevalent in Chinese flocks. The phylogenomic analysis identified three lineages in bvSP, with an enhancement of virulence in the two recently emerged lineages (L2/L3), as evidenced in chicken and embryo infection assays. Notably, the ancestor L1 lineage resembles the Salmonella serovars with higher metabolic flexibilities and more robust environmental tolerance, indicating stepwise evolutionary trajectories towards avian-restricted lineages. Pan-genome analysis pinpointed fimbrial degradation from a virulent lineage. The later engineered fim-deletion mutant, and all other five fimbrial systems, revealed behavior switching that restricted horizontal fecal-oral transmission but boosted virulence in chicks. By depleting fimbrial appendages, bvSP established persistent replication with less proinflammation in chick macrophages and adopted vertical transovarial transmission, accompanied by ever-increasing intensification in the poultry industry. Together, we uncovered a previously unseen paradigm for remodeling bacterial surface appendages that supplements virulence-enhanced evolution with increased vertical transmission.

Gut-targeted nanoparticles deliver specifically targeted antimicrobial peptides against Clostridium perfringens infections

Specifically targeted antimicrobial peptides (STAMPs) are novel alternatives to antibiotics, whereas the development of STAMPs for colonic infections is hindered by limited de novo design efficiency and colonic bioavailability. In this study, we report an efficient de novo STAMP design strategy that combines a traversal design, machine learning model, and phage display technology to identify STAMPs against Clostridium perfringens. STAMPs could physically damage C. perfringens, eliminate biofilms, and self-assemble into nanoparticles to entrap pathogens. Further, a gut-targeted engineering particle vaccine (EPV) was used for STAMPs delivery. In vivo studies showed that both STAMP and EPV@STAMP effectively limited C. perfringens infections and then reduced inflammatory response. Notably, EPV@STAMP exhibited stronger protection against colonic infections than STAMPs alone. Moreover, 16S ribosomal RNA sequencing showed that both STAMPs and EPV@STAMP facilitated the recovery of disturbed gut microflora. Collectively, our work may accelerate the development of the discovery and delivery of precise antimicrobials.

Whole genome sequencing and analysis of selenite-reducing bacteria Bacillus paralicheniformis SR14 in response to different sugar supplements

The biosynthetic process of selenium nanoparticles (SeNPs) by specific bacterial strain, whose growth directly affects the synthesis efficiency, has attracted great attentions. We previously reported that Bacillus paralicheniformis SR14, a SeNPs-producing bacteria, could improve intestinal antioxidative function in vitro. To further analyze the biological characteristics of SR14, whole genome sequencing was used to reveal the genetic characteristics in selenite reduction and sugar utilization. The results reviewed that the genome size of SR14 was 4,448,062 bp, with a GC content of 45.95%. A total of 4300 genes into 49 biological pathways was annotated to the KEGG database. EC: 1.1.1.49 (glucose-6-phosphate 1-dehydrogenase) and EC: 5.3.1.9 (glucose-6-phosphate isomerase), were found to play a potential role in glucose degradation and EC:2.7.1.4 (fructokinase) might be involved in the fructose metabolism. Growth profile and selenite-reducing ability of SR14 under different sugar supplements were determined and the results reviewed that glucose had a better promoting effect on the reduction of selenite and growth of bacteria than fructose, sucrose, and maltose. Moreover, RT-qPCR experiment proved that glucose supplement remarkably promoted the expressions of thioredoxin, fumarate reductase, and the glutathione peroxidase in SR14. Analysis of mRNA expression showed levels of glucose-6-phosphate dehydrogenase and fructokinase significantly upregulated under the supplement of glucose. Overall, our data demonstrated the genomic characteristics of SR14 and preliminarily determined that glucose supplement was most beneficial for strain growth and SeNPs synthesis.

A Cross-Sectional Study of Companion Animal-Derived Multidrug-Resistant Escherichia coli in Hangzhou, China

Antimicrobial resistance poses a challenge to global public health, and companion animals could serve as the reservoir for antimicrobial-resistant bacteria. However, the prevalence of antimicrobial-resistant bacteria, especially multidrug-resistant (MDR) bacteria, and the associated risk factors from companion animals are partially understood. Here, we aim to investigate the prevalence of MDR Escherichia coli, as an indicator bacterium, in pet cats and dogs in Hangzhou, China, and evaluate the factors affecting the prevalence of MDR E. coli. The proportion of pets carrying MDR E. coli was 35.77% (49/137), i.e., 40.96% (34/83) for dogs and 27.28% (15/54) for cats. Isolates resistant to trimethoprim-sulfamethoxazole (49.40% and 44.44%), amoxicillin-clavulanic acid (42.17% and 38.89%), and nalidixic acid (40.96% and 35.19%) were the most prevalent in dogs and cats. Interestingly, comparable prevalence of MDR E. coli was observed in pet dogs and cats regardless of the health condition and the history of antibiotic use. Genetic diversity analysis indicates a total of 86 sequencing types (23 clonal complexes), with ST12 being the most dominant. Further genomic investigation of a carbapenem-resistant E. coli ST410 isolate reveals abundant antimicrobial-resistance genes and a plasmid-borne carbapenemase gene (NDM-5) flanked by insertion sequences of IS91 and IS31, suggesting the plasmid and insertion sequences may be involved in carbapenem-resistance dissemination. These data show that companion animal-derived MDR bacteria could threaten public health, and further regulation and supervision of antimicrobial use in pet clinics should be established in China. IMPORTANCE MDR Escherichia coli are considered a global threat because of the decreasing options for antimicrobial therapy. Companion animals could be a reservoir of MDR E. coli, and the numbers of pets and households owning pets in China are booming. However, the prevalence and risk factors of MDR E. coli carriage in Chinese pets were rarely studied. Here, we investigated the prevalence of MDR E. coli in pets in Hangzhou, one of the leading cities with the most established pet market in China, and explored the factors that affected the prevalence. Our findings showed high prevalences of MDR E. coli in pet dogs and cats regardless of their health condition and the history of antibiotic use, suggesting their potential role of public health risk. A call-to-action for improved regulation of antimicrobial use in companion animal is needed in China.