Enterococcus faecium HDRsEf1 Promotes Systemic Th1 Responses and Enhances Resistance to SalmonellaTyphimurium Infection.

The gut microbiota is known to regulate the immune system and thereby influence susceptibility to infection. In this study, we observed that the administration of Enterococcus faecium HDRsEf1 (HDRsEf1) led to an improvement in the development of the immune system. This was evidenced by an increase in both the spleen index and the area of spleen white pulp. Specifically, the proportion of T helper (Th) 1 cells and the production of IFN-γ and IL-12 were significantly increased in the spleens of mice treated with HDRsEf1. In agreement with the in vivo results, we found that Th1-related cytokines, including IFN-γ and IL-12p70, were strongly induced in splenocytes treated with HDRsEf1. In addition, Th1 cell activation and high-level secretion of IL-12p70 were also confirmed by coculture of CD4+ T cells with bone marrow-derived dendritic cells treated with HDRsEf1. Moreover, the employment of HDRsEf1 was identified to augment resilience against systemic infection provoked by S. Typhimurium and stimulate the expression of the genes for TNFα and iNOS in the initial stage of infection, signifying that reinforced Th1 cells and IL-12 might activate macrophages for antibacterial safeguards. In summary, our study suggests that HDRsEf1 could act as an effective immunobiotic functional agent, promoting systemic Th1 immunological responses and priming defenses against infection.

Autophagy is a defense mechanism controlling Streptococcus suis serotype 2 infection in murine microglia cells.

Streptococcus suis (S. suis) is an important swine and human pathogen, causing severe meningitis with high morbidity and mortality worldwide. Microglial activation and inflammation are responsible for bacterial meningitis. S. suis has been identified to activate microglia, but the role of autophagy following S. suis infection in microglial cells remains elusive. In this study, using western blot, immunofluorescent staining and transmission electron microscopy (TEM), we demonstrated that S. suis serotype 2 (SS2) triggered autophagosome and enhanced autophagic flux in BV2 microglial cells. Autophagy activators, rapamycin, could further promote autophagy in S. suis-infected BV2 cells. Conversely, autophagy inhibitors including siRNA targeting ATG5, Beclin-1, ATG9a and ATG12 attenuated the autophagic process. Consistent with the in vitro results, autophagy was activated following S. suis infection in brain tissue including frontal cortex and hippocampus in a mouse model of meningitis. Further experiment showed that autophagy serves as a cellular defense mechanism to limit invaded bacteria and microglia inflammation in S. suis-infected BV2 cells. This is the first study reporting that the interaction between autophagy and microglia cells in response to S. suis infection. The possible mechanism involved could additionally suggest potential therapeutic approaches for bacterial meningitis.

Genetic and Molecular Characterization of H9N2 Avian Influenza Viruses Isolated from Live Poultry Markets in Hubei Province, Central China, 2013-2017.

H9N2 subtype avian influenza virus (AIV) is an influenza A virus that is widely spread throughout Asia, where it jeopardizes the poultry industry and provides genetic material for emerging human pathogens. To better understand the epidemicity and genetics of H9 subtype AIVs, we conducted active surveillance in live poultry markets (LPMs) in Hubei Province from 2013 to 2017. A total of 4798 samples were collected from apparent healthy poultry and environment. Real-time RT-PCR revealed that the positivity rate of influenza A was 26.6% (1275/4798), of which the H9 subtype accounted for 50.3% (641/1275) of the positive samples. Of the 132 H9N2 viral strains isolated, 48 representative strains were subjected to evolutionary analysis and genotyping. Phylogenetic analysis revealed that all H9N2 viral genes had 91.1%-100% nucleotide homology, clustered with genotype 57, and had high homology with human H9N2 viruses isolated from 2013 to 2017 in China. Using a nucleotide divergence cutoff of 95%, we identified ten distinct H9N2 genotypes that continued to change over time. Molecular analysis demonstrated that six H9N2 isolates had additional potential glycosylation sites at position 218 in the hemagglutinin protein, and all isolates had I155T and Q226L mutations. Moreover, 44 strains had A558V mutations in the PB2 protein and four had E627V mutations, along with H9N2 human infection strains A/Beijing/1/2016 and A/Beijing/1/2017. These results emphasize that the H9N2 influenza virus in Hubei continues to mutate and undergo mammalian adaptation changes, indicating the necessity of strengthening the surveillance of the AIV H9N2 subtype in LPMs.

Carbonyl anti-(α-Amino)allylation via Ruthenium Catalyzed Hydrogen Autotransfer: Use of an Acetylenic Pyrrole as an Allylmetal Pronucleophile.

A single ruthenium complex catalyzes two discrete transformations resulting in the net conversion of an acetylenic pyrrole and alcohols to products of carbonyl anti-(α-amino)allylation. An initial catalytic process enables isomerization of an alkyne to a kinetically more reactive allene. A second catalytic process promotes alcohol-to-allene hydrogen transfer to form an aldehyde-allylruthenium pair that engages in regio- and diastereoselective carbonyl addition. A related reductive coupling of aldehydes mediated by 2-propanol also is described. The present catalytic processes represent rare examples of the use of alkynes as nucleophilic allylmetal precursors.

Nickel-Catalyzed Cross-Coupling of Vinyl Dioxanones to Form Enantiomerically Enriched Cyclopropanes.

Under the conditions of nickel(0) catalysis, enantiomerically enriched vinyl dioxanones engage boroxines or B2(pin)2 in stereospecific cross-coupling to form diverse tetrasubstituted cyclopropanes bearing all-carbon quaternary stereocenters. The collective data corroborate a mechanism involving nickel(0)-mediated benzylic oxidative addition with inversion of stereochemistry followed by reversible olefin insertion to form a (cyclopropylcarbinyl)nickel complex, which upon reductive elimination releases the cyclopropane.

Regioselective Hydrohydroxyalkylation of Styrene with Primary Alcohols or Aldehydes via Ruthenium-Catalyzed C-C Bond Forming Transfer Hydrogenation.

Transfer hydrogenative coupling of styrene with primary alcohols using the precatalyst HClRu(CO)(PCy3 )2 modified by AgOTf or HBF4 delivers branched or linear adducts from benzylic or aliphatic alcohols, respectively. Related 2-propanol mediated reductive couplings also are described.

Haemophilus parasuis infection activates chemokine RANTES in PK-15 cells.

RANTES is a member of the CC chemokine involved in inflammation and immune response during pathogen infection. In our previous study, Haemophilus parasuis (H. parasuis), which is responsible for the great economic losses in the pig industry worldwide, has been shown to enhance RANTES expression in PK-15 cells. However, the mechanisms behind this biological phenomenon have remained unclear. In this study, we showed that H. parasuis infection significantly upregulated RANTES gene transcription in a time- and dose-dependent manner. Promoter analysis by site-directed mutagenesis indicated that the nuclear factor NF-κB binding site was the most important cis-regulatory element controlling H. parasuis-induced RANTES transcription. Inhibition of NF-κB and JNK activity also significantly reduced H. parasuis-induced RANTES production. In addition, TLRs signaling pathway was found to be involved in H. parasuis induced-RANTES expression. These results represent an important molecular mechanism whereby H. parasuis induced RANTES in the inflammatory response.

Haemophilus parasuis induces activation of NF-κB and MAP kinase signaling pathways mediated by toll-like receptors.

Glässer's disease in pigs caused by Haemophilus parasuis is characterized by a severe membrane inflammation. In our previous study, we have identified activation of the transcription factor NF-κB after H. parasuis infection of porcine epithelial cells. In this study, we found that H. parasuis infection also contributed to the activation of p38/JNK MAPK pathway predominantly linked to inflammation, but not the ERK MAPK pathway associated with growth, differentiation and development. Inhibition of NF-κB, p38 and JNK but not ERK activity significantly reduced IL-8 and CCL4 expression by H. parasuis. We also found TLR1, TLR2, TLR4 and TLR6 were required for NF-κB, p38 and JNK MAPK activation. Furthermore, MyD88 and TRIF signaling cascades were essential for H. parasuis-induced NF-κB activation. These results provided new insights into the molecular pathways underlying the inflammatory response induced by H. parasuis.

A colorimetric and ratiometric fluorescent probe for ClO- targeting in mitochondria and its application in vivo.

A colorimetric and ratiometric fluorescent probe PMN-TPP for imaging mitochondrial ClO- was prepared. The selectivity of PMN-TPP was excellent and the detection would not be influenced by other ROS. The limit of detection (LOD = 3σ/slope) for ClO- was evaluated to be 0.43 µM, suggesting the probe's high sensitivity to ClO-. For the biological applications, PMN-TPP performed well in detecting endogenous HClO in living RAW264.7 macrophage cells. A co-localization study employing Mito Tracker green revealed that PMN-TPP was specifically located in the mitochondria of living RAW264.7 macrophage cells. In the in vivo experiment, a nude mouse with acute inflammation stimulated by lipopolysaccharide (LPS) was employed. After injection of PMN-TPP, the fluorescence signal changed gradually in 30 min and then remained unchanged in the injection region, demonstrating that PMN-TPP could detect the endogenous HClO in living animals.

A fast-responsive mitochondria-targeted fluorescent probe detecting endogenous hypochlorite in living RAW 264.7 cells and nude mouse.

A very fast-responsive fluorescent probe PZ-Py for imaging mitochondrial HClO/ClO(-), with a relatively long emission wavelength, was prepared. The limit of detection was evaluated to be 17.9 nM. Moreover, the probe PZ-Py was successfully applied in the imaging of endogenous HClO/ClO(-) in the mitochondria of RAW 264.7 cells and living nude mouse.

A highly selective turn-on fluorescent probe for Al(III) based on coumarin and its application in vivo.

In this study, a turn-on coumarin-based fluorescent probe, 7-hydroxy-6-[(2-hydroxy-naphthalen-1-ylmethylene)-amino]-4-methyl-chroman-2-one (CN), was developed for detecting Al(3+) in aqueous systems. The binding ratio of CN-Al(3+) complexes was determined from the Job plot and ESI-MS data to be 1 : 1. The binding constant (Ka) of Al(3+) binding to CN was calculated to be 9.55 × 10(4) M(-1) from a Benesi-Hildebrand plot and the detection limit was evaluated to be as low as 0.10 µM (LOD = 3σ/slope). CN could be used as an effective fluorescent probe for detecting Al(3+) in living HeLa cells. Moreover, CN could also be applied in the in vivo detection of Al(3+) in zebrafish.