Phakellisins A-E, cyclopeptides from a marine sponge Phakellia sp. guided by LC-MS.

A chemical investigation of the marine sponge Phakellia sp. from the South China Sea yielded five new cyclopeptides, phakellisins A-E (1-5). Structures of these compounds were determined by comprehensive analysis of 1D/2D NMR, HRESIMS/MS spectroscopic data and the advanced Marfey's method. All compounds were evaluated for their cytotoxic activity. Compound 1 showed a strong inhibitory activity against WSU-DLCL-2 cells with an IC50 value of 5.25 ± 0.2 µM by induction of G0/G1 cell cycle arrest and apoptosis.

LC-MS-Guided Isolation of Cyanogripeptides A-C, Cyclolipopeptides with ß-Methyl-Leucine Residues, from an Actinoalloteichus cyanogriseus LHW52806.

Cyanogripeptides A-C (1-3), three new cyclolipopeptides with unusual ß-methyl-leucine residues, were identified from an Actinoalloteichus cyanogriseus LHW52806 using an LC-MS-guided strategy. The structures of compounds 1-3 were elucidated by 1D/2D NMR, HR-MS/MS, and the advanced Marfey's method. The absolute configuration of the ß-methyl-leucine residue was determined by a combination of stereoselective biosynthesis of (2S,3R)-ß-methyl-leucine, racemization to its epimer (2R,3R)-ß-methyl-leucine, and the advanced Marfey's method. The biosynthetic pathway of cyanogripeptides was deduced by analyzing the genome of A. cyanogriseus LHW52806. Compound 3 exhibited antibacterial activity against Helicobacter pylori G27, Helicobacter pylori 26695, and Mycolicibacterium smegmatis ATCC607 with MIC values of 32 µg/mL.

Axinellasins A-D, Immunosuppressive Cycloheptapeptide Diastereomers, Discovered via a Precursor Ion Scanning-Supercritical Fluid Chromatography Strategy from the Marine Sponge Axinella species.

The precursor ion scanning-supercritical fluid chromatography (PI-SFC) method was applied to explore new methionine sulfoxide-containing cycloheptapeptides, axinellasins A-D (1-4), from the marine sponge Axinella sp. Their structures, including absolute configurations, were elucidated by detailed spectroscopic analyses and X-ray crystallography. The total synthesis of 4 was completed via an Fmoc solid/solution-phase synthesis. Compounds 1-4 exhibited immunosuppressive effects via inhibition of T and B cell proliferation, and 1 and 4 showed better inhibitory activities than their corresponding diastereomers.

RNA-seq profiles of chicken type II pneumocyte in response to Escherichia coli infection.

Avian pathogenic Escherichia coli (APEC) causes great economic loss to the poultry industry worldwide. Chicken type II pneumocytes (CP II cells) secrete surfactants and modulate lung immunity to decrease the infection of the invading pathogen. Nevertheless, the pathogenesis of CP II cells to APEC infection remains poorly understood. Therefore, we conducted global gene expression profiling of CP II cells after APEC-O78 infection to explore the host-pathogen interaction. The differentially expressed genes of CP II cells to APEC infection were characterized by RNA-seq with EB-seq algorithm. In consequence, the mRNA of 18996 genes was identified, and CP II cells responded to APEC infection with marked changes in the expression of 1390 genes. Among them, there are 803 down-regulated mRNAs and 587 up-regulated mRNAs. The KEGG prediction and Gene Ontology terms analysis revealed that the major enriched pathways were related to NF-κB signaling pathway, apoptosis pathway, tight junction, and cytokine-cytokine receptor interaction and other pathways. We adopted qRT-PCR to verify the validity of the selected gene expression. The fold induction of qPCR was similar to the RNA-seq results. These results provide a better understanding of the pathogenesis of APEC, especially apoptosis pathway involved in APEC infection.

Canine distemper virus increased the differentiation of CD4+CD8+ T cells and mRNA expression of inflammatory cytokines in peripheral blood lymphocyte from canine.

BACKGROUND: Canine distemper virus (CDV) can cause a highly contagious disease to canid. However, how CDV affects peripheral blood lymphocyte (PBL) remains unclear. METHODS: In this study, CDV infected PBL was cultured to investigate the effect of CDV on the differentiation of lymphocytes and the mRNA expression of inflammatory cytokines in PBL. RESULTS: The results showed that CDV changed the phenotype of lymphocytes and increased the percentage of CD4+CD8+ T cells. To explore the effect of immune response of lymphocytes to CDV, the mRNA expression of pro- and anti-inflammatory cytokines was examined. Interleukin (IL-6, IL-12B), and tumor necrosis factor (TNF)-α mRNA expression was significantly increased at 12-48 h after CDV infection. IL-10 mRNA expression was dramatically enhanced at 12-36 h after CDV infection. However, IL-4 and transforming growth factor (TGF-ß) were not response to CDV infection. These results indicated that PBL differentiated intoCD4+CD8+ T cells and improved the inflammatory response to CDV infection. CONCLUSIONS: After CDV infection, PBL differentiated into CD4+CD8+ T cells and initiated inflammatory response.

Anti-bacterial activity of baicalin against APEC through inhibition of quorum sensing and inflammatory responses.

Avian pathogenic Escherichia coli (APEC), collectively known as causative agent of extraintestinal infections, is an important cause of morbidity and mortality in poultry. Currently, quorum sensing (QS), biofilm formation and virulence factors are considered as novel prospective targets for antimicrobial therapy to control APEC invasion. In addition, inflammatory responses are also served as the major pathological features of APEC invasion. This study was aimed to explore the effect of baicalin on APEC and APEC-induced inflammatory responses. After treatment with baicalin, we mainly examined the AI-2 secretion, biofilm formation, expression of virulence genes of APEC, and the levels of inflammatory cytokines, as well as the expression of NF-κB pathway. Our results showed that baicalin significantly inhibited the QS via decreasing the AI-2 secretion, biofilm formation, and the expression of virulence genes of APEC such as LsrB, LsrK, LuxS, pfs, H-NS, fimA, fimB, fyuA, csgA, csgB, and rpoS. Moreover, baicalin significantly attenuated the release of lactate dehydrogenase (LDH), and the adhesion of APEC to chicken type II pneumocytes to reduce cell damage. Furthermore, baicalin also inhibited the expression of pro-inflammatory cytokines and NF-κB activation. Thus, our data revealed that baicalin could interfere with the quorum sensing, biofilm formation and virulence genes expression to relieve the APEC pathogenicity. Additionally, baicalin decreased the inflammatory responses of chicken type II pneumocytes induced by APEC. Taken together, these data provide a novel potential pharmaco-therapeutic approach to chicken colibacillosis.

Baicalin protects mice against Salmonella typhimurium infection via the modulation of both bacterial virulence and host response.

BACKGROUND: The worsening problems of antibiotic resistance prompt the need for alternative strategies. Baicalin, which is isolated from Scutellaria baicalensisi, has been demonstrated to exhibit anti-inflammatory, anti-virulence and antimicrobial effects. Salmonella typhimurium is an important foodborne pathogenic bacteriaum that causes gastrointestinal disease in humans and many animals. PURPOSE: The aim of this study was to investigate the effects of baicalin on S. typhimurium infection in mice and its possible mechanism in vitro. STUDY DESIGN: To evaluate the effect of baicalin in vivo, mice were orally administered of baicalin, and then were infected by an intragastric administration of S. typhimurium. The minimal inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of baicalin, baicalein, and oroxylin A against S. typhimurium were detected under the guides of the Clinical and Laboratory Standards Institute. In vitro, Caco-2 cells were infected with S. typhimurium in the presence or absence of baicalin, baicalein, and oroxylin A at sub-MICs. METHODS: In the in vivo experiment, the body weight loss, the serum levels of TNFα,  IL-6, and lactic dehydrogenase (LDH), the pathological changes of the caecum and the caecum bacterial burdens were examined. The MICs and MBCs of baicalin, baicalein, and oroxylin A against S. typhimurium were detected by two-fold serial dilutions. In vitro, Caco-2 cells were infected with S. typhimurium, and the invasion capacity, TNFα, nitrate, and LDH were analysed. The transcription levels of Salmonella pathogenicity island 1 virulence associated genes (sopB, sopE, sopE2) of S. typhimurium in the presence of baicalin, baicalein, and oroxylin A were detected by qRT-PCR. RESULTS: Our results showed that baicalin significantly decreased the body weight loss, the serum levels of TNFα,  IL-6, and LDH, and the caecum bacterial burdens of mice challenged with S. typhimurium. Histological examination showed that baicalin decreased the lesion in the caecum of S. typhimurium-infected mice. MICs and MBCs of baicalin, and oroxylin A. against S. typhimurium were > 128 µg/ml. MICs and MBCs of baicalein against S. typhimurium were 64 µg/ml, and > 128 µg/ml, respectively. Pretreatment of Caco-2 cells or S. typhimurium with baicalin, baicalein, and oroxylin A significantly inhibited the invasion of Caco-2 cells by S. typhimurium in a dose-dependent manner. Sub-MICs of baicalin, baicalein, and oroxylin A also significantly decreased the levels of TNFα, nitrate, and LDH from S. typhimurium-infected Caco-2 cells. Moreover, the transcription levels of sopB, sopE, and sopE2 were significantly suppressed by baicalin, baicalein, and oroxylin A. CONCLUSIONS: These results demonstrated that baicalin is a promising agent for the prevention of S. typhimurium infection via the modulation of both bacterial virulence and host response.

Rutin inhibits quorum sensing, biofilm formation and virulence genes in avian pathogenic Escherichia coli.

The study aimed to investigate whether rutin affects the quorum sensing (QS) of avian pathogenic Escherichia coli (APEC). In this study, APEC-O78 was selected as the test strain. We mainly examined the effects of rutin on the AI-2 secretion by bioluminescence assay, biofilm formation through a crystal violet staining method, and expression of virulence genes of APEC by qRT-PCR. We found that rutin can significantly interfering with QS through reducing the secretion of AI-2, inhibited the biofilm formation, and reduced the expression of virulence genes of APEC. Moreover, rutin markedly decreased adhesion and damage of APEC to chicken type II pneumocytes. These results suggested rutin reduces cell damage of APEC-infected chicken type II pneumocytes through interfering with QS via decreasing AI-2 production, biofilm formation, and the expression of virulence genes. This paper may provide a new evidence for colibacillosis prevention in chicken.

In vitro antiviral efficacy of caffeic acid against canine distemper virus.

Canine distemper (CD) is a highly contagious disease caused by the canine distemper virus (CDV), and mortality can be as high as 100%. However, there is no specific treatment for CD. In this study, the antiviral activity of the caffeic acid against CDV was evaluated in vitro. The results showed that the IC50 of the caffeic acid against CDV at 1 and 2 h post infection (PI) is 23.3 and 32.3 µg/mL, respectively. Consistently, at 1 and 2 h PI, the caffeic acid exhibited a reduced (23.3-57.0% and 37.2-38.1%) viral inhibitory effect in vero cells. Furthermore, the caffeic acid plus Ribavirin (RBV) has greater antiviral activity against CDV than the caffeic acid or RBV individually. In addition, the caffeic acid reduced the total viral RNA synthesis by 59-86% at 24-72 h. Therefore, our data provided the experimental evidence that the caffeic acid effectively inhibited CDV infection in vero cells, which may potentially be used to treat clinical disease associated with CDV infection.

Autoinducer-2 of quorum sensing is involved in cell damage caused by avian pathogenic Escherichia coli.

Avian pathogenic Escherichia coli (APEC) infections are responsible for great losses in the poultry industry. Quorum sensing (QS) acts as a global regulatory system that controls genes involved in bacterial pathogenesis, metabolism and protein biosynthesis. However, whether QS of APEC is related to cell damage has not been elucidated. In the present study, we explored the correlation between the damage of chicken type II pneumocytes induced by APEC and the autoinducer-2 (AI-2) activity of APEC. The results showed that when chicken type II pneumocytes were co-cultured with 108 CFU/ml of APEC-O78 for 6 h, the release of LDH reached the highest level (192.5 ± 13.4 U/L) (P < 0.01), and the percentages of dead cells followed the same trend in trypan blue exclusion assay. In addition, the AI-2 activity of cell-free culture fluid (CF) reached the maximum value after 6 h co-culture with 108 CFU/ml of APEC-O78. At the same time, the mRNA expressions of eight virulence genes (papC, fimA, fimC, hlyE, ompA, luxS, pfs, and qseA) of 108 CFU/ml APEC-O78 were significantly increased compared with those of 107 CFU/ml, and the mRNA expressions of four virulence genes (hlyE, tsh, iss, and luxS) of 108 CFU/ml APEC-O78 were higher than those of 109 CFU/ml (p < 0.05) after incubation for 6 h. These results suggested that AI-2-mediated QS is involved in the cell damage induced by APEC-O78, indicating AI-2 may be one new potential target for preventing chicken colibacillosis.