Novel cyclohexyl-amides as potent antibacterials targeting bacterial type IIA topoisomerases

As part of our wider efforts to exploit novel mode of action antibacterials, we have discovered a series of cyclohexyl-amide compounds that has good Gram positive and Gram negative potency. The mechanism of action is via inhibition of bacterial topoisomerases II and IV. We have investigated various subunits in this series and report advanced studies on compound 7 which demonstrates good PK and in vivo efficacy properties.     

Novel amino-piperidines as potent antibacterials targeting bacterial type IIA topoisomerases

We have identified a series of amino-piperidine antibacterials with a good broad spectrum potency. We report the investigation of various subunits in this series and advanced studies on compound 8. Compound 8 possesses good pharmacokinetics, broad spectrum antibacterial activity and demonstrates oral efficacy in a rat lung infection model.     

Microautophagy of cytosolic proteins by late endosomes

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Highlights? Late endosomes take up cytosolic proteins through membrane invaginations ? Endosomal microautophagy (eMI) requires multivesicular body formation ? hsc70 mediates selective targeting of cytosolic proteins during eMI ? hsc70 binds to the endosomal membrane through its polybasic cluster     

The quenching effect of flavonoids on 4-methylumbelliferone, a potential pitfall in fluorimetric neuraminidase inhibition assays

Many assays aimed to test the inhibitory effects of synthetic molecules, and naturally occurring products on the neuraminidase activity exploit the hydrolysis of 2'-O-(4-methylumbelliferyl)-N-acetylneuraminic acid (4-MUNANA). The amount of the released product, 4-methylumbelliferone (4-MU), is then measured fluorimetrically. The authors attempted an analysis of the inhibitory properties of 35 naturally occurring flavonoids on neuraminidase N3, where only 29 of them were sufficiently soluble in the assay medium. During the analysis, the authors noticed a strong quenching effect due to the test compounds on the fluorescence of 4-MU. The quenching constants for the flavonoids were determined according to the Stern-Volmer approach. The extent of fluorescence reduction due to quenching and the magnitude of the fluorescence reduction measured in the inhibition assays were comparable: for 11 of 29 compounds, the two values were found to be coincident within the experimental uncertainty. These data were statistically analyzed for correlation by calculating the pertinent Pearson correlation coefficient. Inhibition and quenching were found to be positively correlated (r = 0.71, p(uncorr) = 1.5 × 10(-5)), and the correlation was maintained for the whole set of tested compounds. Altogether, the collected data imply that all of the tested flavonoids could produce false-positive results in the neuraminidase inhibition assay using 4-MUNANA as a substrate.     

Reconciling deep calibration and demographic history: bayesian inference of post glacial colonization patterns in Carcinus aestuarii (Nardo, 1847) and C. maenas (Linnaeus, 1758)

A precise inference of past demographic histories including dating of demographic events using bayesian methods can only be achieved with the use of appropriate molecular rates and evolutionary models. Using a set of 596 mitochondrial cytochrome c oxidase I (COI) sequences of two sister species of European green crabs of the genus Carcinus (C. maenas and C. aestuarii), our study shows how chronologies of past evolutionary events change significantly with the application of revised molecular rates that incorporate biogeographic events for calibration and appropriate demographic priors. A clear signal of demographic expansion was found for both species, dated between 10,000 and 20,000 years ago, which places the expansions events in a time frame following the Last Glacial Maximum (LGM). In the case of C. aestuarii, a population expansion was only inferred for the Adriatic-Ionian, suggestive of a colonization event following the flooding of the Adriatic Sea (18,000 years ago). For C. maenas, the demographic expansion inferred for the continental populations of West and North Europe might result from a northward recolonization from a southern refugium when the ice sheet retreated after the LGM. Collectively, our results highlight the importance of using adequate calibrations and demographic priors in order to avoid considerable overestimates of evolutionary time scales.     

Severe and persistent depletion of circulating plasmacytoid dendritic cells in patients with 2009 pandemic H1N1 infection

Background

Dysregulation of host immune responses plays a critical role in the pathogenesis of severe 2009 pandemic H1N1 infection. Whether H1N1 virus could escape innate immune defense in vivo remains to be investigated. The aim of this study was to evaluate the pattern of innate immune response during human 2009 H1N1 infection. We performed the enumeration of circulating myeloid dendritic cells (mDC) and plasmacytoid DC (pDC) in blood from patients with H1N1 pneumonia shortly after the onset of symptoms and during follow-up at different intervals of time. The analysis of CD4 and CD8 count, CD38 T-cell activation marker and serum cytokine/chemokine plasma levels was also done.

Methodology/Principal Findings

Blood samples were collected from 13 hospitalized patients with confirmed H1N1-related pneumonia at time of admission and at weeks 1, 4, and 16 of follow-up. 13 healthy donors were enrolled as controls. In the acute phase of the disease, H1N1-infected patients exhibited a significant depletion in both circulating pDC and mDC in conjunction with a decrease of CD4 and CD8 T cell count. In addition, we found plasmatic hyperproduction of IP-10 and RANTES, whereas increase in T-cell immune activation was found at all time points. When we assessed the changes in DC count over time, we observed a progressive normalization of mDC number. On the contrary, H1N1-infected patients did not achieve a complete recovery of pDC count as values remained lower than healthy controls even after 16 weeks of follow-up.

Conclusions

H1N1 disease is associated with a profound depletion of DC subsets. The persistence of pDC deficit for several weeks after disease recovery could be due to H1N1 virus itself or to a preexisting impairment of innate immunity.     

BH(4) (tetrahydrobiopterin)-dependent activation, but not the expression, of inducible NOS (nitric oxide synthase)-2 in proinflammatory cytokine-stimulated, cultured normal human astrocytes is mediated by MEK-ERK kinases

Nitric oxide (NO) from astrocytes is one of the signalers used by the brain's extensive glial-neuronal-vascular network, but its excessive production by pro-inflammatory cytokine-stimulated glial cells can be cytodestructive. Here, we show how three pro-inflammatory cytokines (IL-1beta, TNF-alpha, and IFN-gamma) together stimulated the activation, but not the prior expression, of NOS-2 protein via a mechanism involving MEK-ERKs protein kinases in astrocytes from adult human cerebral temporal cortex. The cytokines triggered a transient burst of p38 MAPK activity and the production of NOS-2 mRNA which were followed by bursts of MEK-ERK activities, synthesis of the NOS-2 co-factor tetrahydrobiopterin (BH(4)), a build-up of NOS-2 protein and from it active NOS-2 enzyme. Selectively inhibiting MEK1/MEK2, but not the earlier burst of p38 MAPK activity, with a brief exposure to U0126 between 24 and 24.5 h after adding the cytokine triad affected neither NOS-2 expression nor NOS-2 protein accumulation but stopped BH(4) synthesis and the assembly of the NOS-2 protein into active NOS-2 enzyme. The complete blockage of active NOS-2 production by the brief exposure to U0126 was bypassed by simply adding BH(4) to the culture medium. Therefore, this cytokine triad triggered two completely separable, tandem operating mechanisms in normal human astrocytes, the first being NOS-2 gene expression and accumulation of NOS-2 protein and the second being the synthesis of the BH(4) factor needed to dimerize the NOS-2 protein into active, NO-making NOS-2 enzyme.     

Human peripheral blood eosinophils induce angiogenesis

Eosinophils play a crucial role in allergic reactions and asthma. They are also involved in responses against parasites, in autoimmune and neoplastic diseases, and in fibroses. There is increasing evidence that angiogenesis plays an important role in these processes. Since eosinophils are known to produce angiogenic mediators, we have hypothesized a direct contribution of these cells to angiogenesis. The effect of human peripheral blood eosinophil sonicates on rat aortic endothelial cell proliferation (in vitro), rat aorta sprouting (ex vivo) and angiogenesis in the chick embryo chorioallantoic membrane (in vivo) have been investigated. To determine whether eosinophil-derived vascular endothelial growth factor influences the eosinophil pro-angiogenic activity, eosinophil sonicates were incubated with anti-vascular endothelial growth factor antibodies and then added to the chorioallantoic membrane. Vascular endothelial growth factor mRNA expression and vascular endothelial growth factor receptor density on the endothelial cells were also evaluated. Eosinophils were found to enhance endothelial cell proliferation and to induce a strong angiogenic response both in the aorta rings and in the chorioallantoic membrane assays. Pre-incubation of eosinophil sonicates with anti-vascular endothelial growth factor antibodies partially reduced the angiogenic response of these cells in the chorioallantoic membrane. Eosinophils also increased vascular endothelial growth factor mRNA production on endothelial cells. Eosinophils are able to induce angiogenesis and this effect is partially mediated by their pre-formed vascular endothelial growth factor. This strongly suggests an important role of eosinophils in angiogenesis-associated diseases such as asthma.