Effects of a novel Bacillus subtilis GXYX crude lipopeptide against Salmonella enterica serovar Typhimurium infection in mice.

The increased rate of antibiotic resistance strongly limits the resolution of Salmonella enterica serovar Typhimurium (S. Typhimurium) infection. Therefore, new strategies to control bacterial infections are urgently needed. Bacillus subtilis (B. subtilis) and its metabolites are desirable antibacterial agents. Here, we aimed to evaluate the antibacterial activity of the novel B. subtilis strain GXYX (No: PRJNA940956) crude lipopeptide against S. Typhimurium. In vitro, GXYX crude lipopeptides affected S. Typhimurium biofilm formation and swimming and attenuated the adhesion and invasion abilities of S. Typhimurium toward BHK-21 cells; in addition, it inhibited the mRNA expression of the filA, filC, csgA, and csgB genes, which are related to the adhesion and invasion ability of S. Typhimurium. In vivo, pretreatment with GXYX crude lipopeptide via intragastric administration improved the survival rate by 30%, which was related to reductions in organ bacterial loads and clinical signs in mice. Intragastric administration of GXYX crude lipopeptide significantly downregulated the mRNA levels of TNF-α, IL-1ß, IL-12 and IL-6 in response to S. Typhimurium-induced inflammation compared with intraperitoneal injection. Moreover, it significantly improved the intestinal barrier-related gene (ZO-1, claudin-1, occludin-1) mRNA levels in intestinal tissue damaged by S. Typhimurium infection. In conclusion, GXYX crude lipopeptides were effective at reducing S. Typhimurium colonization, laying a foundation for the further development of novel antibacterial agents.

Characterization of AI-2/LuxS quorum sensing system in biofilm formation, pathogenesis of Streptococcus equi subsp. zooepidemicus.

Streptococcus equi subsp. zooepidemicus (SEZ) is an opportunistic pathogen of both humans and animals. Quorum sensing (QS) plays an important role in the regulation of bacterial group behaviors. The aim of this study was to characterize the LuxS in SEZ and evaluate its impact on biofilm formation, pathogenesis and gene expression. The wild-type SEZ and its LuxS mutant (ΔluxS) were examined for growth, biofilm formation, virulence factors, and transcriptomic profiles. Our results showed that LuxS deficiency did not affect SEZ hemolytic activity, adhesion or capsule production. For biofilm assay demonstrated that mutation in the luxS gene significantly enhances biofilm formation, produced a denser biofilm and attached to a glass surface. RAW264.7 cell infection indicated that ΔluxS promoted macrophage apoptosis and pro-inflammatory responses. In mice infection, there was no significant difference in mortality between SEZ and ΔluxS. However, the bacterial load in the spleen of mice infected with ΔluxS was significantly higher than in those infected with SEZ. And the pathological analysis further indicated that spleen damage was more severe in the ΔluxS group. Moreover, transcriptomics analysis revealed significant alterations in carbon metabolism, RNA binding and stress response genes in ΔluxS. In summary, this study provides the first evidence of AI-2/LuxS QS system in SEZ and reveals its regulatory effects on biofilm formation, pathogenicity and gene expression.

ALKBH5 Suppresses Autophagy in Prostate Cancer Cells via Inhibiting m6A-Modification of TSPAN1 mRNA.

BACKGROUND: Activating autophagy promotes the invasion and progression of prostate cancer (PCa). Tetraspanin 1 (TSPAN1) has been found to promote autophagy flux and its up-regulation can enhance the migration of PCa cells. In addition, there is a binding relationship between TSPAN1 and the N6-methyladenosine (m6A) demethylase AlkB homolog 5 (ALKBH5). Therefore, we wanted to know whether ALKBH5 could affect autophagy by regulating TSPAN1 expression, and thereby participate in PCa malignant progression. METHODS: The expression of ALKBH5 and TSPAN1 in PCa was examined by quantitative real-time polymerase chain reaction (qRT-PCR), and the functional tests included cell counting kit-8 and 5-ethynyl-2'-deoxyuridine (EdU) staining assays. The expression of autophagy-related proteins was confirmed by western blot. Detection of the m6A level of TSPAN1 was performed using methylated RNA immunoprecipitation sequencing (MeRIP)-qPCR. RESULTS: ALKBH5 was significantly downregulated in PCa cells (LNCaP, DU145 and PC3 cells; p < 0.001). Overexpression of ALKBH5 inhibited cell viability and the number of EdU-positive cells (p < 0.01, p < 0.001), decreased the ratio of microtubule-associated protein light chain 3B (LC3B)-II/LC3B-I, and promoted P62 protein expression in LNCaP and DU145 cells (p < 0.001). The m6A level of TSPAN1 was high in LNCaP and DU145 cells, but was inhibited by the overexpression of ALKBH5 (p < 0.001). TSPAN1 overexpression promoted cell viability (p < 0.001), increased EdU-positive cells and the LC3B-II/LC3B-I ratio (p < 0.001, p < 0.05), reduced P62 protein expression (p < 0.05, p < 0.001), and reversed the regulation of ALKBH5 overexpression in LNCaP and DU145 cells (p < 0.01, p < 0.001). CONCLUSIONS: Promoting ALKBH5 expression may inhibit PCa autophagy by reducing the m6A level of TSPAN1.

Edwardsiella tarda Causing Septicemia in a Wild Crested Ibis (Nipponia nippon).

An adult Crested Ibis (Nipponia nippon) was found moribund in the Qinling area of China. Postmortem examination and histopathological analysis revealed lung inflammation and multi-organ hemorrhage. Bacterial isolation and whole-genome sequencing confirmed Edwardsiella tarda infection.

Caspase-1 deficiency impairs neutrophils recruitment and bacterial clearance in Streptococcus equi ssp. zooepidemicus infected mice.

Streptococcus equi ssp. zooepidemicus (S. zooepidemicus, SEZ) is a zoonotic bacterial pathogen that can cause various inflammation, including pneumonia. As the most abundant leukocytes in the circulation, neutrophils are the first wave of leukocytes to arrive in the lung upon infection. This study aims to evaluate the effect of caspase-1 on the host response to SEZ infection in a mouse model. Intranasal exposure to SEZ induced the expression of caspase-1 in wild-type mice lung, and increased the number of neutrophils in the alveolar cavity and alveolar wall. In addition, caspase-1 deficiency reduced the transcription levels of IL-1α, IL-1ß, IL-6, and TNF-α in the lungs of infected mice, which was accompanied by decreased recruitment of pulmonary neutrophils. Moreover, knocking out caspase-1 decreased the bactericidal activity of neutrophils and promoted the pulmonary bacterial load. In line with this, the mortality of caspase-1-/- mice infected with SEZ was significantly increased compared with those of caspase-1+/+ mice. Collectively, recruiting neutrophils and enhancing the bactericidal ability of neutrophils are important means for caspase-1 to promote bacterial clearance.

Practice and exploration of the "student-centered" multielement fusion teaching mode in human anatomy.

PURPOSE: Human anatomy is a core course of basic medicine and the first professional course for medical students. Traditional teaching includes "teacher-centered" instruction, passive learning, and a lack of interaction between teachers and students as well as between students. The aim of this study was to develop a "student-centered" multielement fusion teaching mode to address the mentioned drawbacks. METHODS: A total of 141 clinical medical students from grades 2016 and 2017 of Chengde Medical University participated in this study. The students were randomly divided into four classes: two experimental classes and two control classes. The experimental classes experienced a "student-centered" multielement fusion teaching mode, while the control classes experienced a traditional teaching method. Formative assessments and questionnaires were used to assess the students' preferences and obtain feedback. Theoretical and experimental tests were carried out to detect the students' scores at the end of the semester. RESULTS: The results of the questionnaires demonstrated that 100% of the students agreed that the multielement teaching mode was better. In the experimental test, the students in the experimental group achieved a mean score of 16.50 ± 0.3203, which was significantly higher than that of the control group 12.65 ± 0.4731 (P < 0.01). In the theoretical test, the average score of the experimental group was 45.86 ± 0.6273 and that of the control group was 46.59 ± 0.6636; thus, there was no significant difference between the two groups (P > 0.05). CONCLUSION: The application of a "student-centered" multielement fusion teaching mode obtained strong approval from the students. This teaching mode not only improved students' interest in learning and increased the interaction between teachers and students as well as between students but also enhanced students' competence and will lay a solid foundation for their future careers.

First-in-class humanized FSH blocking antibody targets bone and fat.

Blocking the action of FSH genetically or pharmacologically in mice reduces body fat, lowers serum cholesterol, and increases bone mass, making an anti-FSH agent a potential therapeutic for three global epidemics: obesity, osteoporosis, and hypercholesterolemia. Here, we report the generation, structure, and function of a first-in-class, fully humanized, epitope-specific FSH blocking antibody with a KD of 7 nM. Protein thermal shift, molecular dynamics, and fine mapping of the FSH-FSH receptor interface confirm stable binding of the Fab domain to two of five receptor-interacting residues of the FSHß subunit, which is sufficient to block its interaction with the FSH receptor. In doing so, the humanized antibody profoundly inhibited FSH action in cell-based assays, a prelude to further preclinical and clinical testing.

Whole genome sequence and comparative genome analyses of multi-resistant Staphylococcus warneri GD01 isolated from a diseased pig in China.

Staphylococcus warneri is a coagulase-negative staphylococcus that is a normal inhabitant of the skin. It is also considered to be an opportunistic etiological agent causing significant infections in human and animals. Currently, relatively little attention has been paid to the genome biology of S. warneri pathogenicity and antibiotic resistance, which are emerging issues for this etiological agent with considerably clinical significance. In this study, we determined the complete genome sequence of S. warneri strain GD01 recovered from the sampled muscle abscess tissue of a diseased pig in South China. The genome of S. warneri is composed of a circular chromosome of 2,473,911 base pairs as well as eight plasmid sequences. Genome-wide metabolic reconstruction revealed 82 intact functional modules driving the catabolism of respiration and fermentation for energy production, uptake of distinct sugars as well as two-component regulatory systems. The evidence uncovered herein enables better understanding for metabolic potential and physiological traits of this etiological agent. The antibiotic susceptibility test demonstrated that S. warneri GD01 was resistant to penicillin, amoxicillin, ampicillin, cefalexin, vancomycin, and sulfisoxazole. The associations between antibiotic phenotypes and the related genotypes were identified to reveal the molecular basis conferring resistance to this pathogen. A number of genes coding for potential virulence factors were firstly depicted in the genome of S. warneri GD01, including adhesins, exoenzymes, capsule, and iron acquisition proteins. Our study provides a valuable genomic context of the genes/modules devoting to metabolism, antibiotic resistance, and virulence of S. warneri.

CD44 facilitates adherence of Streptococcus equi subsp. zooepidemicus to LA-4 cells.

Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) causes a wide variety of infections in many species. CD44 is a transmembrane adhesion molecule, expressed by various cell types, which has been implicated in several infection processes. The aim of this study was to examine the role of CD44 in S. zooepidemicus adherence to LA-4 cells (mouse lung adenoma). Dose-dependent adhesion with LA-4 may be effectively studied by flow cytometry. Adherence of S. zooepidemicus is reduced after treatment of cells with anti-CD44 antibody. Treatment of S. zooepidemicus with recombinant CD44 significantly reduced bacteria adherence. In addition, CD44 can directly bind to wild-type S. zooepidemicus, while the binding was decreased in the capsule deletion isogenic mutant. These data suggest that CD44 facilitates adherence of S. zooepidemicus to LA-4 cells.

Ultrasound­targeted microbubble destruction­mediated miR­205 enhances cisplatin cytotoxicity in prostate cancer cells.

MicroRNAs (miRNAs) are non­coding ~20 nucleotides long sequences that function in the initiation and development of a number of cancers. Ultrasound­targeted microbubble destruction (UTMD) is an effective method for microRNA delivery. The aim of the present study was to investigate the potential roles of UTMD­mediated miRNA (miR)­205 delivery in the development of prostate cancer (PCa). In the present study, miR­205 expression was examined by reverse transcription­quantitative polymerase chain reaction assay. miR­205 mimics were transfected into PC­3 cells using the UTMD method, and the PC­3 cells were also treated with cisplatin. Cell proliferation, apoptosis, migration and invasion abilities were detected using Cell Counting kit­8, flow cytometry, wound healing and Transwell assays, respectively. In addition, the protein expression levels of caspase­9, cleaved­caspase 9, cytochrome c (cytoc), epithelial (E)­cadherin, matrix metalloproteinase­9 (MMP­9), phosphorylated (p)­extracellular signal­regulated kinase (ERK) and ERK were measured by western blot analysis. The results of the present study demonstrated that miR­205 expression was low in human PCa cell lines compared with healthy cells and that UTMD­mediated miR­205 delivery inhibited PCa cell proliferation, migration and invasion, and promoted apoptosis modulated by cisplatin compared with UTMD­mediated miR­negative control group and miR­205­treated group. Furthermore, it was demonstrated that UTMD­mediated miR­205 transfection increased the expression of caspase­9, cleaved­caspase 9, cytochrome c and E­cadherin, and decreased the expression of MMP­9 and p­ERK. Therefore, UTMD­mediated miR­205 delivery may be a promising method for the treatment of PCa.

Characterization of SeseC_01411 as a surface protective antigen of Streptococcus equi ssp. zooepidemicus.

Streptococcus equi ssp. zooepidemicus (Streptococcus zooepidemicus, SEZ) is a commensal bacterium related to opportunistic infections of many species, including humans, dogs, cats, and pigs. SeseC_01411 has been proven to be immunogenic. However, its protective efficacy remained to be evaluated. In the present study, the purified recombinant SeseC_01411 could elicit a strong humoral antibody response and protect against lethal challenge with virulent SEZ in mice. Our finding confirmed that SeseC_01411 distributes on the surface of SEZ. In addition, the hyperimmune sera against SeseC_01411 could efficiently kill the bacteria in the phagocytosis test. The present study identified the immunogenic protein, SeseC_01411, as a novel surface protective antigen of SEZ.

Neuroprotective effect of the active components of three Chinese herbs on brain iron load in a mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative brain disorder and the most common cause of dementia. New treatments for AD are required due to its increasing prevalence in aging populations. The present study evaluated the effects of the active components of Epimedium, Astragalus and Radix Puerariae on learning and memory impairment, ß-amyloid (Aß) reduction and brain iron load in an APPswe/PS1ΔE9 transgenic mouse model of AD. Increasing evidence indicates that a disturbance of normal iron homeostasis may contribute to the pathology of AD. However, the underlying mechanisms resulting in abnormal iron load in the AD brain remain unclear. It has been hypothesized that the brain iron load is influenced by the deregulation of certain proteins associated with brain iron metabolism, including divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1). The present study investigated the effects of the active components of Epimedium, Astragalus and Radix Puerariae on the expression levels of DMT1 and FPN1. The treatment with the active components reduced cognitive deficits, inhibited Aß plaque accumulation, reversed Aß burden and reduced the brain iron load in AD model mice. A significant increase was observed in the levels of DMT1-iron-responsive element (IRE) and DMT1-nonIRE in the hippocampus of the AD mouse brain, which was reduced by treatment with the active components. In addition, the levels of FPN1 were significantly reduced in the hippocampus of the AD mouse brain compared with those of control mice, and these levels were increased following treatment with the active components. Thus, the present study indicated that the active components of Epimedium, Astragalus and Radix Puerariae may exert a neuroprotective effect against AD by reducing iron overload in the AD brain and may provide a novel approach for the development of drugs for the treatment of AD.

Modes of action of ADP-ribosylated elongation factor 2 in inhibiting the polypeptide elongation cycle: a modeling study.

Despite the fact that ADP-ribosylation of eukaryotic elongation factor 2 (EF2) leads to inhibition of protein synthesis, the mechanism by which ADP-ribosylated EF2 (ADPR•EF2) causes this inhibition remains controversial. Here, we applied modeling approaches to investigate the consequences of various modes of ADPR•EF2 inhibitory actions on the two coupled processes, the polypeptide chain elongation and ADP-ribosylation of EF2. Modeling of experimental data indicates that ADPR•EF2 fully blocks the late-phase translocation of tRNAs; but the impairment in the translocation upstream process, mainly the GTP-dependent factor binding with the pretranslocation ribosome and/or the guanine nucleotide exchange in EF2, is responsible for the overall inhibition kinetics. The reduced ADPR•EF2-ribosome association spares the ribosome to bind and shield native EF2 against toxin attack, thereby deferring the inhibition of protein synthesis inhibition and inactivation of EF2. Minimum association with the ribosome also keeps ADPR•EF2 in an accessible state for toxins to catalyze the reverse reaction when nicotinamide becomes available. Our work underscores the importance of unveiling the interactions between ADPR•EF2 and the ribosome, and argues against that toxins inhibit protein synthesis through converting native EF2 to a competitive inhibitor to actively disable the ribosome.

Enhanced proliferation and differentiation of neural stem cells grown on PHA films coated with recombinant fusion proteins.

Polyhydroxyalkanoates (PHAs) belong to a family of copolyesters with demonstrated biocompatibility. We hypothesize that genetically fusing evolutionarily preserved cell binding motifs, such as RGD or IKVAV, to the PHA-binding protein phasin (PhaP) for surface functionalization of PHA materials could better support the growth and differentiation of neural stem cells (NSCs). This hypothesis is tested on three polyester materials of the same aliphatic family: poly(L-lactic acid) (PLA) and two PHB copolymers, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (PHBVHHx). Experimental results indicate that surface coating of the two fusion proteins, PhaP-RGD and PhaP-IKVAV, provides short-term advantages in promoting the adhesion, proliferation and neural differentiation of rat NSCs compared to the PhaP-coated or uncoated material. Among the tested samples, the combination of coating PhaP-IKVAV on an PHBVHHx surface yields the highest levels in cell adhesion and proliferation, while the PLA film coated with PhaP-IKVAV promotes better neural differentiation and neurite outgrowth in the early stage. Because both PhaP-RGD and PhaP-IKVAV could be produced in an inexpensive manner, our data suggest that PhaP-IKVAV is an ideal nonspecific coating agent to functionalize hydrophobic biomaterials in the application of neural tissue engineering.