Chromatin accessibility mediated transcriptome changes contribute to flavor substance alterations and jasmonic acid hyperaccumulation during oolong tea withering process.

During the oolong tea withering process, abiotic stresses induce significant changes in the content of various flavor substances and jasmonic acid (JA). However, the changes in chromatin accessibility during withering and their potential impact remain poorly understood. By integrating ATAC-seq, RNA-seq, metabolite, and hormone assays, we characterized the withering treatment-induced changes in chromatin accessibility, gene expression levels, important metabolite contents, and JA and JA-ILE contents. Additionally, we analyzed the effects of chromatin accessibility alterations on gene expression changes, content changes of important flavor substances, and JA hyperaccumulation. Our analysis identified a total of 3451 open- and 13 426 close-differentially accessible chromatin regions (DACRs) under withering treatment. Our findings indicate that close-DACRs-mediated down-regulated differentially expressed genes (DEGs) resulted in the reduced accumulation of multiple catechins during withering, whereas open-DACRs-mediated up-regulated DEGs contributed to the increased accumulation of important terpenoids, JA, JA-ILE and short-chain C5/C6 volatiles. We further highlighted important DACRs-mediated DEGs associated with the synthesis of catechins, terpenoids, JA and JA and short-chain C5/C6 volatiles and confirmed the broad effect of close-DACRs on catechin synthesis involving almost all enzymes in the pathway during withering. Importantly, we identified a novel MYB transcription factor (CsMYB83) regulating catechin synthesis and verified the binding of CsMYB83 in the promoter-DACRs regions of key catechin synthesis genes using DAP-seq. Overall, our results not only revealed a landscape of chromatin alters-mediated transcription, flavor substance and hormone changes under oolong tea withering, but also provided target genes for flavor improvement breeding in tea plant.

Erianin inhibits the progression of triple-negative breast cancer by suppressing SRC-mediated cholesterol metabolism.

Triple-negative breast cancer (TNBC) is highly malignant and lacks effective biotherapeutic targets. The development of efficient anticancer drugs with low toxicity and few side effects is a hotspot in TNBC treatment research. Although erianin is known to have potent antitumor activity, its regulatory mechanism and target in TNBC have not been fully elucidated, hampering further drug development. This study showed that erianin can significantly inhibit TNBC cell proliferation and migration, promote cell apoptosis, and inhibit the growth of transplanted tumors in mice. Mechanistically, through network pharmacology analysis, molecular docking and cellular thermal shift assays, we preliminarily identified SRC as the cellular target of erianin. Erianin potently inhibited the expression of SRC, which mediated the anticancer effect of erianin in TNBC. Moreover, erianin can downregulate the expression of genes related to cholesterol synthesis and uptake by targeting SRC, interfering with cholesterol levels in TNBC, thereby inhibiting the progression of TNBC in vivo and in vitro. Taken together, our results suggest that erianin may inhibit the progression of TNBC by suppressing SRC-mediated cholesterol metabolism, and erianin has the great potential to be an effective treatment for TNBC patients.

Repurposing harmaline as a novel approach to reverse tmexCD1-toprJ1-mediated tigecycline resistance against klebsiella pneumoniae infections.

BACKGROUND: A novel plasmid-mediated resistance-nodulation-division (RND) efflux pump gene cluster tmexCD1-toprJ1 in Klebsiella pneumoniae tremendously threatens the use of convenient therapeutic options in the post-antibiotic era, including the "last-resort" antibiotic tigecycline. RESULTS: In this work, the natural alkaloid harmaline was found to potentiate tigecycline efficacy (4- to 32-fold) against tmexCD1-toprJ1-positive K. pneumoniae, which also thwarted the evolution of tigecycline resistance. Galleria mellonella and mouse infection models in vivo further revealed that harmaline is a promising candidate to reverse tigecycline resistance. Inspiringly, harmaline works synergistically with tigecycline by undermining tmexCD1-toprJ1-mediated multidrug resistance efflux pump function via interactions with TMexCD1-TOprJ1 active residues and dissipation of the proton motive force (PMF), and triggers a vicious cycle of disrupting cell membrane integrity and metabolic homeostasis imbalance. CONCLUSION: These results reveal the potential of harmaline as a novel tigecycline adjuvant to combat hypervirulent K. pneumoniae infections.

Co-assembled whey protein and proanthocyanidins as a promising biocarrier for hydrophobic pterostilbene: Fabrication, characterization, and cellular antioxidant potential.

The usage of food-derived polyphenols with different polarities has been limited by their instability and incompatibility. Therefore, a biocarrier was developed by co-assembly of whey protein isolate (WPI) and hydrophilic proanthocyanidin (PC) for loading hydrophobic pterostilbene (PTE). Such biocarrier has superior affinity for PTE than WPI alone, as determined by encapsulation efficiency and loading capacity assay, fluorescence quenching analysis, and molecular docking, whereas the assembly process was characterized by particle size and zeta potential, 3-dimensional fluorescence, and scanning electron microscopy. Circular dichroism and Fourier transform infrared spectroscopy spectra confirmed the α-helix to ß-sheet and random coil transition of proteins during the formation of nanocomplexes. Whey protein isolate acted as a mediator through altering the binding mode of PC and PTE, allowing them to perform significant synergistic effects in enhancing 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging and reducing H2O2-induced cell damage. This research may serve to develop new protein/polyphenol co-loading systems and offer a reliable nutritional fortification.

Preventive effects of lactoferrin on acute alcohol-induced liver injury via iron chelation and regulation of iron metabolism.

Lactoferrin is widely found in milk and has the ability to bind iron. Previous studies have reported that lactoferrin was effective in the prevention and treatment of acute alcohol-induced liver injury (AALI). Ferroptosis is a recently discovered cell death and is involved in the development of AALI. However, the potential role of lactoferrin in acute alcohol-induced ferroptosis is still unclear. In this study, we observed that lactoferrin (10, 20 and 40 µg/mL) significantly mitigated alcohol (300 mM)-induced injury in vitro. Additionally, lactoferrin (100 and 200 mg/kg bw) significantly alleviated alcohol (4.8 g/kg bw)-induced injury in vivo. Our results showed that lactoferrin inhibited alcohol-induced upregulation of the ferroptosis marker protein ACSL4 and downregulation of GPX4. Meanwhile, lactoferrin treatment successfully reversed the elevated Malondialdehyde (MDA) levels and the reduced Glutathione (GSH) levels caused by alcohol treatment. These results can indicate that lactoferrin significantly decreased ferroptosis in vivo and in vitro. Lactoferrin has the potential to chelate iron, and our results showed that lactoferrin (20 µg/mL) significantly reduced iron ions and the expression of Ferritin Heavy Chain (FTH) under FeCl3 (100 µM) treatment. It was demonstrated that lactoferrin had a significant iron-chelating effect and reduced iron overload caused by FeCl3 in AML12 cells. Next, we examined iron content and the expression of iron metabolism marker proteins Transferrin Receptor (TFR), Divalent metal transporter 1 (DMT1), FTH, and Ferroportin (FPN). Our results showed that lactoferrin alleviated iron overload induced by acute alcohol. The expression of TFR and DMT1 was downregulated and FPN and FTH were upregulated after lactoferrin treatment in vivo and in vitro. Above all, the study suggested that lactoferrin can alleviate AALI by mitigating acute alcohol-induced ferroptosis. Lactoferrin may offer new strategies for the prevention or treatment of AALI.

Application value of circulating LncRNA in diagnosis, treatment, and prognosis of breast cancer.

Breast cancer is the malignant tumor with the highest incidence in women worldwide. It is highly heterogeneous, has a high incidence of drug resistance, recurrence, and metastasis, and is one of the malignant tumors with the highest mortality rate. The early diagnosis, treatment monitoring, and prognosis assessment of breast cancer are the key factors affecting the survival of patients. However, due to the lack of specific biomarkers, breast cancer is still an essential factor affecting women's quality of life and physical and mental health. Long non-coding RNA can regulate various genes and different signaling pathways and plays an essential role in the occurrence and development of tumors. Recent studies have found that the abnormal expression of circulating long non-coding RNA in serum, saliva, and other biological body fluids plays a significant role in early diagnosis, pathological classification, stage, therapeutic effect monitoring, and prognosis evaluation of breast cancer. This article will review the potential application value of circulating lncRNA in breast cancer.

A new function of thymol nanoemulsion for reversing colistin resistance in Salmonella enterica serovar Typhimurium infection.

BACKGROUND: Adjuvant addition of approved drugs or foodborne additives to colistin might be a cost-effective strategy to overcome the challenge of plasmid-mediated mobile colistin resistance gene emergence, which poses a threat in the clinic and in livestock caused by infections with Gram-negative bacteria, especially carbapenem-resistant Enterobacteriaceae. METHODS: Chequerboard assay was applied to screen the colistin adjuvants from natural compounds. The killing-time curve, combined disc test and membrane permeation assay were conducted to identify the synergy efficacy of thymol and colistin in vitro. Thin-layer chromatography (TLC), LC-MS and fluorescence spectra were used to indicate the interaction of thymol and MCR-1. The potential binding sites were then investigated by molecular simulation dynamics. Finally, a thymol nanoemulsion was prepared with high-pressure homogenization as the clinical dosage form. RESULTS: Thymol presented an excellent synergistic effect in vitro with colistin against Salmonella enterica serovar Typhimurium and Escherichia coli bacteria. Thymol addition, forming a complex with MCR-1, might interfere with the efficacy of MCR-1. Moreover, thymol strengthened colistin activity associated with potentiating membrane damage, destroying the biofilm and enhancing reactive oxygen species-mediated oxidative damage. Thymol nanoemulsion combined with colistin remarkably prevented the intestinal damage caused by S. Typhimurium infection, resulting in a survival rate higher than 60%. CONCLUSIONS: This study achieved a promising thymol oral formulation as colistin adjuvant to combat S. Typhimurium infection, which could be used to extend the lifespan of colistin in clinical veterinary medicine.

Severe Acute Hepatitis Outbreaks Associated with a Novel Hepacivirus in Rhizomys pruinosus in Hainan, China.

Members of the genus Hepacivirus have a broad range of hosts, with at least 14 species identified. To date, a highly pathogenic hepacivirus causing severe disease in animals has not been found. Here, by using high-throughput sequencing, a new hepacivirus was identified as the dominant and highly pathogenic virus in severe acute hepatitis outbreaks in bamboo rats (Rhizomys pruinosus), with ≈80% mortality; this virus emerged in February 2020 in two bamboo rat farms in China. Hepaciviral genome copies in bamboo rat liver were significantly higher than in other organs. Genomic sequences of hepacivirus strains from 12 sick bamboo rats were found to share 85.3 to 100% nucleotide (nt) identity and 94.9 to 100% amino acid (aa) identity and to share 79.7 to 87.8% nt and 90.4 to 97.8% aa identities with previously reported bamboo rat hepaciviruses of Vietnam and China. Sequence analysis further revealed the simultaneous circulation of genetically divergent hepacivirus variants within the two outbreaks. Phylogenetic analysis showed that hepacivirus strains from the present and previous studies formed an independent clade comprised of at least two genotypes, clearly different from all other known species, suggesting a novel species within the genus Hepacivirus. This is the first report of a non-human-infecting hepacivirus causing potentially fatal infection of bamboo rats, and the associated hepatitis in the animals potentially can be used to develop a surrogate model for the study of hepatitis C virus infection in humans and for the development of therapeutic strategies. IMPORTANCE Members of the genus Hepacivirus have a broad host range, with at least 14 species identified, but none is highly pathogenic to its host except for hepatitis C virus, which causes severe liver diseases in humans. In this study, a new liver-tropic hepacivirus species was identified by high-throughput sequencing as the pathogen associated with two outbreaks of severely acute hepatitis in hoary bamboo rats (Rhizomys pruinosus) on two farms in Hainan Province, China; this is the first reported highly pathogenic animal hepacivirus to our knowledge. Further phylogenetic analysis suggested that the hepaciviruses derived from hoary bamboo rats in either the current or previous studies represent a novel species within the genus Hepacivirus. This finding is a breakthrough that has significantly updated our understanding about the pathogenicity of animal hepaciviruses, and the hepacivirus-associated hepatitis in bamboo rats may have a use as an animal infection model to understand HCV infection and develop therapeutic strategies.

Isorhamnetin as a novel inhibitor of pneumolysin against Streptococcus pneumoniae infection in vivo/in vitro.

The increasing incidence of Streptococcus pneumoniae (S. pneumoniae) infection severely threatened the global public heath, causing a significant fatality in immunocompromised hosts. Notably, pneumolysin (PLY) as a pore-forming cytolysin plays a crucial role in the pathogenesis of pneumococcal pneumonia and lung injury. In this study, a natural flavonoid isorhamnetin was identified as a PLY inhibition to suppress PLY-induced hemolysis by engaging the predicted residues and attenuate cytolysin PLY-mediated A549 cells injury. Underlying mechanisms revealed that PLY inhibitor isorhamnetin further contributed to decrease the formation of bacterial biofilms without affecting the expression of PLY. In vivo S. pneumoniae infection confirmed that the pathological injury of lung tissue evoked by S. pneumoniae was ameliorated by isorhamnetin treatment. Collectively, these results presented that isorhamnetin could inhibit the biological activity of PLY, thus reducing the pathogenicity of S. pneumoniae. In summary, our study laid a foundation for the feasible anti-virulence strategy targeting PLY, and provided a promising PLY inhibitor for the treatment of S. pneumoniae infection.

Repurposing rabeprazole sodium as an anti-Clostridium perfringens drug by inhibiting perfringolysin O.

AIMS: Clostridium perfringens infections affect food safety, human health, and the development of the poultry feed industry. Anti-virulence is an alternative strategy to develop new drug. Perfringolysin O (PFO) is an exotoxin of C. perfringens that has been demonstrated to play critical roles in the pathogenesis of this organism, promising it an attractive target to explore drugs to combat C. perfringens infection. METHODS AND RESULTS: Based on an activity-based screening, we identified six PFO inhibitors from the Food and Drug Administration (FDA)-approved drug library, among which rabeprazole sodium (RS) showed an optimal inhibitory effect with an IC50 of 1.82 ± 0.746 µg ml-1. The GLY57, ASP58, SER190, SER193-194, ASN199, GLU204, ASN377, THR379, and ALA200 in PFO interacted with RS during binding based on an energy analysis and H-bond analysis. This interaction blocked the oligomer formation of PFO, thereby inhibiting its cytotoxicity. RS treatment significantly increased the survival rate and alleviated pathological damage in C. perfringens or PFO-treated Galleria mellonella. CONCLUSIONS: RS could potentially be used as a candidate drug for treating C. perfringens infection.

High-protein compound yogurt with quinoa improved clinical features and metabolism of high-fat diet-induced nonalcoholic fatty liver disease in mice.

Gut microbiota dysbiosis plays a crucial role in the occurrence and progression of nonalcoholic fatty liver disease (NAFLD), which may be influenced by nutritional supplementation. Quinoa, a type of pseudocereal, has gained prominence due to its high nutritional value and diverse applications. This study aimed to determine whether yogurt containing quinoa can ameliorate NAFLD and alleviate metabolic disorders by protecting against the divergence of gut microbiota. Our findings suggested that quinoa yogurt could significantly reduce the body weight gain and fat tissue weight of high-fat diet (HFD)-fed obese mice. In addition, quinoa yogurt significantly reduced liver steatosis and enhanced glucose homeostasis and insulin sensitivity. Additional research indicates that quinoa yogurt can reduce the levels of proinflammatory cytokines (i.e., tumor necrosis factor α, IL-1ß, and IL-6) and inhibit endotoxemia and systemic inflammation. The characteristics of the gut microbiota were then determined by analyzing 16S rRNA. In addition, we discovered that the gut microbiota was disturbed by HFD consumption. Particularly, intestinal probiotics and beneficial intestinal secretions were increased, leading to the expression of glucagon-like peptide-1 in the colon, contributing to NAFLD. Furthermore, endotoxemia and systemic inflammation in HFD-fed mice were restored to the level of control mice when they were fed yogurt and quinoa. Therefore, yogurt containing quinoa can effectively alleviate NAFLD symptoms and may exert its effects via microbiome-gut-liver axis mechanisms. According to some research, the role of the enteric-liver axis may also influence metabolic disorders to reduce the development of NAFLD.

The Application of Cinnamon Twig Extract as an Inhibitor of Listeriolysin O against Listeria monocytogenes Infection.

As a major virulence factor of Listeria monocytogenes (L. monocytogenes), listeriolysin O (LLO) can assist in the immune escape of L. monocytogenes, which is critical for the pathogen to evade host immune recognition, leading to various infectious diseases. Cinnamon twig (CT), as a traditional medicine, has been widely used in clinics for multiple functions and it has exhibited excellent safety, efficacy and stability. There are few reports on the effects of the extracts of traditional medicine on bacterial virulence factors. CT has not been reported to be effective in the treatment of L. monocytogenes infection. Therefore, this study aims to explore the preventive effect of CT against L. monocytogenes infection in vivo and in vitro by targeting LLO. Firstly, a hemolysis assay and a cell viability determination are used to detect the effect of CT extract on the inhibition of the cytolytic activity of LLO. The potential mechanism through which CT extract inhibits LLO activity is predicted through network pharmacology, molecular docking assay, real-time polymerase chain reaction (RT-PCR), Western blotting and circular dichroism (CD) analysis. The experimental therapeutic effect of CT extract is examined in a mouse model infected with L. monocytogenes. Then, the ingredients are identified through a high-performance liquid chromatography (HPLC) and thin layer chromatography (TLC) analysis. Here we find that CT extract, containing mainly cinnamic acid, cinnamaldehyde, ß-sitosterol, taxifolin, catechin and epicatechin, shows a potential inhibition of LLO-mediated hemolysis without any antimicrobial activity. The results of the mechanism research show that CT extract treatment can simultaneously inhibit LLO expression and oligomerization. Furthermore, the addition of CT extract led to a remarkable alleviation of LLO-induced cytotoxicity. After treatment with CT extract, the mortality, bacterial load, pathological damage and inflammatory responses of infected mice are significantly reduced when compared with the untreated group. This study suggests that CT extract can be a novel and multicomponent inhibitor of LLO with multiple strategies against L. monocytogenes infection, which could be further developed into a novel treatment for infections caused by L. monocytogenes.

Quercitrin Is a Novel Inhibitor of Salmonella enterica Serovar Typhimurium Type III Secretion System.

The purpose was to screen type III secretory system (T3SS) inhibitors of Salmonella enterica serovar Typhimurium (S. Typhimurium) from natural compounds. The pharmacological activities and action mechanisms of candidate compounds in vivo and in vitro were systematically studied and analyzed. Using a SipA-ß-lactamase fusion reporting system, we found that quercitrin significantly blocked the translocation of SipA into eukaryotic host cells without affecting the growth of bacteria. Adhesion and invasion assay showed that quercitrin inhibited S. Typhimurium invasion into host cells and reduced S. Typhimurium mediated host cell damage. ß-galactosidase activity detection and Western blot analysis showed that quercitrin significantly inhibited the expression of SPI-1 genes (hilA and sopA) and effectors (SipA and SipC). The results of animal experiments showed that quercitrin significantly reduced colony colonization and alleviated the cecum pathological injury of the infected mice. Small molecule inhibitor quercitrin directly inhibited the function of T3SS and provided a potential antibiotic alternative against S. Typhimurium infection. Importance: T3SS plays a crucial role in the bacterial invasion and pathogenesis of S. Typhimurium. Compared with conventional antibiotics, small molecules could inhibit the virulence factors represented by S. Typhimurium T3SS. They have less pressure on bacterial vitality and a lower probability of producing drug resistance. Our results provide strong evidence for the development of novel inhibitors against S. Typhimurium infection.

Genome-wide identification and characterization of active ingredients related ß-Glucosidases in Dendrobium catenatum.

BACKGROUND: Dendrobium catenatum/D. officinale (here after D. catenatum), a well-known economically important traditional medicinal herb, produces a variety of bioactive metabolites including polysaccharides, alkaloids, and flavonoids with excellent pharmacological and clinical values. Although many genes associated with the biosynthesis of medicinal components have been cloned and characterized, the biosynthetic pathway, especially the downstream and regulatory pathway of major medicinal components in the herb, is far from clear. ß-glucosidases (BGLUs) comprise a diverse group of enzymes that widely exist in plants and play essential functions in cell wall modification, defense response, phytohormone signaling, secondary metabolism, herbivore resistance, and scent release by hydrolyzing ß-D-glycosidic bond from a carbohydrate moiety. The recent release of the chromosome-level reference genome of D. catenatum enables the characterization of gene families. Although the genome-wide analysis of the BGLU gene family has been successfully conducted in various plants, no systematic analysis is available for the D. catenatum. We previously isolated DcBGLU2 in the BGLU family as a key regulator for polysaccharide biosynthesis in D. catenatum. Yet, the exact number of DcBGLUs in the D. catenatum genome and their possible roles in bioactive compound production deserve more attention. RESULTS: To investigate the role of BGLUs in active metabolites production, 22 BGLUs (DcBGLU1-22) of the glycoside hydrolase family 1 (GH1) were identified from D. catenatum genome. Protein prediction showed that most of the DcBGLUs were acidic and phylogenetic analysis classified the family into four distinct clusters. The sequence alignments revealed several conserved motifs among the DcBGLU proteins and analyses of the putative signal peptides and N-glycosylation site revealed that the majority of DcBGLU members dually targeted to the vacuole and/or chloroplast. Organ-specific expression profiles and specific responses to MeJA and MF23 were also determined. Furthermore, four DcBGLUs were selected to test their involvement in metabolism regulation. Overexpression of DcBGLU2, 6, 8, and 13 significantly increased contents of flavonoid, reducing-polysaccharide, alkaloid and soluble-polysaccharide, respectively. CONCLUSION: The genome-wide systematic analysis identified candidate DcBGLU genes with possible roles in medicinal metabolites production and laid a theoretical foundation for further functional characterization and molecular breeding of D. catenatum.

Acacetin attenuates Streptococcus suis virulence by simultaneously targeting suilysin and inflammation.

Streptococcus suis (S. suis), an important zoonotic pathogenic bacterium, can cause multiple diseases and fatal infections in both humans and animals. The emergence of highly virulent and extensively drug-resistant strains of S. suis has raised questions about the efficacy of available therapeutic agents, thereby necessitating novel therapeutic strategies. Suilysin (SLY) is one of the most essential determinants of virulence for the pathogenicity of S. suis capsular type 2 (SS2). In addition, inhibiting the excessive inflammatory response is a strategy to reduce the damage caused by SS2 infection. In this study, we identified acacetin as an effective inhibitor of SLY, which inhibited the oligomerisation of SLY without affecting bacterial growth. Furthermore, the addition of 4-16 µg/ml acacetin to the co-infection system of the cells reduced S. suis-induced inflammation by downregulating the activation of the MAPK signalling pathway, thereby alleviating the S. suis-mediated cell injury. Thus, in addition to the conventional antibiotic therapy, acacetin represent a potential drug candidate and strategy for the treatment of S. suis infections as it simultaneously inhibited the haemolytic activity of SLY and downregulated the inflammatory response.

Pogostone Enhances the Antibacterial Activity of Colistin against MCR-1-Positive Bacteria by Inhibiting the Biological Function of MCR-1.

The emergence of the plasmid-mediated colistin resistance gene mcr-1 has resulted in the loss of available treatments for certain severe infections. Here we identified a potential inhibitor of MCR-1 for the treatment of infections caused by MCR-1-positive drug-resistant bacteria, especially MCR-1-positive carbapenem-resistant Enterobacteriaceae (CRE). A checkerboard minimum inhibitory concentration (MIC) test, a killing curve test, a growth curve test, bacterial live/dead assays, scanning electron microscope (SEM) analysis, cytotoxicity tests, molecular dynamics simulation analysis, and animal studies were used to confirm the in vivo/in vitro synergistic effects of pogostone and colistin. The results showed that pogostone could restore the bactericidal activity of colistin against all tested MCR-1-positive bacterial strains or MCR-1 mutant−positive bacterial strains (FIC < 0.5). Pogostone does not inhibit the expression of MCR-1. Rather, it inhibits the binding of MCR-1 to substrates by binding to amino acids in the active region of MCR-1, thus inhibiting the biological activity of MCR-1 and its mutants (such as MCR-3). An in vivo mouse systemic infection model, pogostone in combination with colistin resulted in 80.0% (the survival rates after monotherapy with colistin or pogostone alone were 33.3% and 40.0%) survival at 72 h after infection of MCR-1-positve Escherichia coli (E. coli) ZJ487 (blaNDM-1-carrying), and pogostone in combination with colistin led to one or more order of magnitude decreases in the bacterial burdens in the liver, spleen and kidney compared with pogostone or colistin alone. Our results confirm that pogostone is a potential inhibitor of MCR-1 for use in combination with polymyxin for the treatment of severe infections caused by MCR-1-positive Enterobacteriaceae.

Synergistic Effect of Lithocholic Acid with Gentamicin against Gram-Positive Bacteria but Not against Gram-Negative Bacteria.

Listeria monocytogenes (L. monocytogenes) is an important Gram-positive food-borne pathogen that severely threatens public health. A checkerboard microdilution method was performed to evaluate the synergistic effect of lithocholic acid (LCA) with Gentamicin (Genta) against L. monocytogenes. BacLight LIVE/DEAD staining, scanning electron microscopy and biofilm inhibition assays were further used to explore the bactericidal effect and antibiofilm effect of this combination on L. monocytogenes. Additionally, the synergistic effects of LCA derivatives with Genta were also evaluated against L. monocytogenes, S.aureus and S. suis. The results indicated that a synergistic bactericidal effect was observed for the combined therapy of LCA at the concentration without affecting bacteria viability, with Genta. Additionally, LCA in combination with Genta had a synergistic effect against Gram-positive bacteria (L. monocytogenes, S. aureus and S. suis) but not against Gram-negative bacteria (E. coli, A. baumannii and Salmonella). BacLight LIVE/DEAD staining and scanning electron microscopy analysis revealed that the combination of LCA with Genta caused L. monocytogenes membrane injury, leading to bacteria death. We found that 8 µg/mL LCA treatment effectively improved the ability of Genta to eradicate L. monocytogenes biofilms. In addition, we found that chenodeoxycholic acid, as a cholic acid derivative, also improved the bactericidal effect of Genta against Gram-positive bacteria. Our results indicate that LCA represents a broad-spectrum adjuvant with Genta for infection caused by L. monocytogenes and other Gram-positive pathogens.

Corilagin: A Novel Antivirulence Strategy to Alleviate Streptococcus pneumoniae Infection by Diminishing Pneumolysin Oligomers.

Pneumolysin (PLY) is a significant virulence factor of Streptococcus pneumoniae (S. pneumoniae), able to break through the defense system of a host and mediate the occurrence of a series of infections. Therefore, PLY as the most ideal target to prevent S. pneumoniae infection has received more and more attention and research. Corilagin is a tannic acid that exhibits excellent inhibition of PLY oligomers without bacteriostatic activity to S. pneumoniae. Herein, hemolytic activity assays, cell viability tests and western blot experiments are executed to evaluate the antivirulence efficacy of corilagin against PLY in vitro. Colony observation, hematoxylin and eosin (H&E) staining and cytokines of bronchoalveolar lavage fluid (BALF) are applied to assess the therapeutic effect of corilagin in mice infected by S. pneumoniae. The results indicate the related genes of corilagin act mainly via enrichment in pathways associated with pneumonia disease. Furthermore, molecular docking and molecular dynamics simulations show that corilagin might bind with domains 3 and 4 of PLY and interfere with its hemolytic activity, which is further confirmed by the site-directed mutagenesis of PLY. Additionally, corilagin limits PLY oligomer production without impacting PLY expression in S. pneumoniae cultures. Moreover, corilagin effectively relieves PLY-mediated cell injury without any cytotoxicity, even then reducing the colony count in the lung and the levels of pro-inflammatory factors in BALF and remarkably improving lung lesions. All the results demonstrate that corilagin may be a novel strategy to cope with S. pneumoniae infection by inhibiting PLY oligomerization.

Piceatannol Alleviates Clostridium perfringens Virulence by Inhibiting Perfringolysin O.

Clostridium perfringens (C. perfringens) is an important foodborne pathogen that can cause diseases such as gas gangrene and necrotizing enteritis in a variety of economic animals, seriously affecting public health and the economic benefits and healthy development of the livestock and poultry breeding industry. Perfringolysin O (PFO) is an important virulence factor of C. perfringens and plays critical roles in necrotic enteritis and gas gangrene, rendering it an ideal target for developing new drugs against infections caused by this pathogen. In this study, based on biological activity inhibition assays, oligomerization tests and computational biology assays, we found that the foodborne natural component piceatannol reduced pore-forming activity with an inhibitory ratio of 83.84% in the concentration of 16 µg/mL (IC50 = 7.83 µg/mL) by binding with PFO directly and changing some of its secondary structures, including 3-Helix, A-helix, bend, and in turn, ultimately affecting oligomer formation. Furthermore, we confirmed that piceatannol protected human intestinal epithelial cells from the damage induced by PFO with LDH release reduced by 38.44% at 16 µg/mL, based on a cytotoxicity test. By performing an animal experiment, we found the C. perfringens clones showed an approximate 10-fold reduction in infected mice. These results suggest that piceatannol may be a candidate for anti-C. perfringens drug development.

Dryocrassin ABBA ameliorates Streptococcus pneumoniae-induced infection in vitro through inhibiting Streptococcus pneumoniae growth and neutralizing pneumolysin activity.

To explore the role of dryocrassin ABBA (ABBA) in the prevention and treatment of Streptococcus pneumoniae (S. pneumoniae) infections in vitro, a minimal inhibitory concentration test, growth curve assay, hemolysis assay, BacLight LIVE/DEAD staining experiments, oligomerization inhibition assay, time-killing test, LDH release detection assay and cytotoxicity test were performed to evaluate the efficacy of ABBA against S. pneumoniae infections in vitro. The results indicated that ABBA treatment exists bactericidal effect on S. pneumoniae at a concentration of less than 8 µg/ml. Furthermore, ABBA was effective at inhibiting the oligomerization of pneumolysin (PLY) from reducing its hemolytic activity. Meanwhile, ABBA could ameliorate cell injury by neutralizing the biological activity of PLY without cytotoxicity. In summary, ABBA was a leading compound against S. pneumoniae infections through bactericidal effect and neutralizing PLY activity.