Identification of siRNA delivery enhancers by a chemical library screen

Most delivery systems for small interfering RNA therapeutics depend on endocytosis and release from endo-lysosomal compartments. One approach to improve delivery is to identify small molecules enhancing these steps. It is unclear to what extent such enhancers can be universally applied to different delivery systems and cell types. Here, we performed a compound library screen on two well-established siRNA delivery systems, lipid nanoparticles and cholesterol conjugated-siRNAs. We identified fifty-one enhancers improving gene silencing 2–5 fold. Strikingly, most enhancers displayed specificity for one delivery system only. By a combination of quantitative fluorescence and electron microscopy we found that the enhancers substantially differed in their mechanism of action, increasing either endocytic uptake or release of siRNAs from endosomes. Furthermore, they acted either on the delivery system itself or the cell, by modulating the endocytic system via distinct mechanisms. Interestingly, several compounds displayed activity on different cell types. As proof of principle, we showed that one compound enhanced siRNA delivery in primary endothelial cells in vitro and in the endocardium in the mouse heart. This study suggests that a pharmacological approach can improve the delivery of siRNAs in a system-specific fashion, by exploiting distinct mechanisms and acting upon multiple cell types.     

Potential role of potassium channel openers in the treatment of asthma and chronic obstructive pulmonary disease

Airway smooth muscle (ASM) cells express various types of potassium (K+) channels which play a key role in determining the resting membrane potential, a relative electrical stability and the responsiveness to both contractile and relaxant agents. In addition, K+ channels are also involved in modulation of neurotransmitter release from airway nerves. The most important K+ channels identified in airways include large and small Ca2+-activated, delayed-rectifier, and ATP-sensitive channels. These K+ channels are structurally and functionally different, thus playing distinct roles in airway electrophysiology and pharmacology. Many in vitro and in vivo studies, performed in both animals and humans, have shown that K+ channel openers are able to induce hyperpolarization of ASM cells, bronchodilation, suppression of airway hyperresponsiveness (AHR), and inhibition of neural reflexes. Therefore, airway K+ channels represent a suitable pharmacological target for the development of new effective therapeutic options in the treatment of asthma and chronic obstructive pulmonary disease (COPD).     

Fas ligand expression in TM4 Sertoli cells is enhanced by estradiol "in situ" production

The testis is an immunologically privileged site of the body where Sertoli cells work on to favor local immune tolerance by testicular autoantigens segregation and immunosuppressive factors secretion. Fas/Fas Ligand (FasL) system, expressed prevalently in Sertoli cells, has been considered to be one of the central mechanisms in testis immunological homeostasis. In different cell lines it has been reported that the proapoptotic protein FasL is regulated by 17-beta estradiol (E2). Thus, using as experimental model mouse Sertoli cells TM4, which conserve a large spectrum of functional features present in native Sertoli cells, like aromatase activity, we investigated if estradiol "in situ" production may influence FasL expression. Our results demonstrate that an aromatizable androgen like androst-4-ene-3,17-dione (Delta4) enhanced FasL mRNA, protein content and promoter activity in TM4 cells. The treatment with N(6),2'-O-dibutyryladenosine-3'-5'-cyclic monophosphate [(Bu)(2)cAMP] (simulating FSH action), that is well known to stimulate aromatase activity in Sertoli cells, amplified Delta4 induced FasL expression. Functional studies of mutagenesis, electrophoretic mobility shift (EMSA) and chromatin immunoprecipitation (ChIP) assays revealed that the Sp-1 motif on FasL promoter was required for E2 enhanced FasL expression in TM4 cells. These data let us to recruit FasL among those genes whose expression is up-regulated by E2 through a direct interaction of ERalpha with Sp-1 protein. Finally, evidence that an aromatizable androgen is able to increase FasL expression suggests that E2 production by aromatase activity may contribute to maintain the immunoprivilege status of Sertoli cells.     

Serum neuron-specific enolase in various pathological conditions.

Quantitative determination of neuron-specific enolase in the serum was performed by RIA method in 18 neurological patients and in 22 patients with pulmonary diseases. The data confirmed that the specificity of this marker is not absolute for the detection both of the nature and of the seat of origin of the disease. Further problems are posed in patients which simultaneously suffer from endocrine, nervous and pulmonary abnormality.     

Neuropeptide expression in the airways of COPD patients and smokers with normal lung function

Neurogenic mechanisms seem to play a role in the pathogenesis of chronic obstructive pulmonary disease (COPD), as suggested by a number of in vitro data. However, few studies have investigated the presence of neuropeptides in the airways of patients with COPD, and they have yielded conflicting results. The aim of this study is to compare the expression of the neuropeptide substance P (SP), vasoactive intestinal peptide (VIP), and neuropeptide Y (NPY) in the airways of smokers with and without COPD. Surgical lung samples were obtained from 15 smokers with COPD and 16 smokers with normal lung function, who underwent lobectomy for a solitary lung carcinoma. Airway expression and distribution of SP, VIP, and NPY were identified by immunohistochemistry and analyzed by a computerized image analysis system. Compared to smokers with normal lung function, COPD patients exhibited an increased immunoreactivity for SP and VIP, paralleled by a decreased NPY expression in the epithelium and glands, and a decreased expression of all these three neuropeptides in the smooth muscle layer. Therefore, in the present study we have documented a different expression and distribution of the neuropeptides SP, VIP, and NPY in the airways of smokers with and without COPD. These findings suggest a possible involvement of such neuropeptides in the pathogenesis of some changes occurring in COPD.     

Integration of Chemical and RNAi Multiparametric Profiles Identifies Triggers of Intracellular Mycobacterial Killing

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Highlights? A high-content chemical screen identifies modulators of intracellular mycobacteria ? Three compounds that kill bacteria by altering host processes were validated ? Multiparametric chemical and genetic data sets integrated to identify mode of action ? Modulation of autophagy and endosomal trafficking identified as mode of action     

Host plant defense signaling in response to a coevolved herbivore combats introduced herbivore attack

Defense‐free space resulting from coevolutionarily naïve host plants recently has been implicated as a factor facilitating invasion success of some insect species. Host plants, however, may not be entirely defenseless against novel herbivore threats. Volatile chemical‐mediated defense signaling, which allows plants to mount specific, rapid, and intense responses, may play a role in systems experiencing novel threats. Here we investigate defense responses of host plants to a native and exotic herbivore and show that (1) host plants defend more effectively against the coevolved herbivore, (2) plants can be induced to defend against a newly‐associated herbivore when in proximity to plants actively defending against the coevolved species, and (3) these defenses affect larval performance. These findings highlight the importance of coevolved herbivore‐specific defenses and suggest that naïveté or defense limitations can be overcome via defense signaling. Determining how these findings apply across various host–herbivore systems is critical to understand mechanisms of successful herbivore invasion.     

Effects of hydrogen peroxide on MAPK activation, IL-8 production and cell viability in primary cultures of human bronchial epithelial cells

The airway epithelium is continuously exposed to inhaled oxidants, including airborne pollutants and cigarette smoke, which can exert harmful proinflammatory and cytotoxic effects. Therefore, the aim of our study was to investigate, in primary cultures of human bronchial epithelial cells (HBEC), the signal transduction pathways activated by increasing concentrations (0.25, 0.5, and 1 mM) of hydrogen peroxide (H(2)O(2)), as well as their effects on IL-8 production and cell viability. The reported results show that H(2)O(2) elicited, in a concentration-dependent fashion, a remarkable increase in phosphorylation-dependent activation of mitogen-activated protein kinases (MAPKs), associated with a significant induction of IL-8 synthesis and a dramatically enhanced cell death. Pre-treatment of HBEC with MAPK inhibitors was able to significantly inhibit the effects of H(2)O(2) on IL-8 secretion, and to effectively prevent cell death. Therefore, these findings suggest that MAPKs play a key role as molecular transducers of the airway epithelial injury triggered by oxidative stress, as well as potential pharmacologic targets for indirect antioxidant intervention.     

Functional properties of hepatocytes in vitro are correlated with cell polarity maintenance

Exploring the cell biology of hepatocytes in vitro could be a powerful strategy to dissect the molecular mechanisms underlying the structure and function of the liver in vivo. However, this approach relies on appropriate in vitro cell culture systems that can recapitulate the cell biological and metabolic features of the hepatocytes in the liver whilst being accessible to experimental manipulations. Here, we adapted protocols for high-resolution fluorescence microscopy and quantitative image analysis to compare two primary hepatocyte culture systems, monolayer and collagen sandwich, with respect to the distribution of two distinct populations of early endosomes (APPL1 and EEA1-positive), endocytic capacity, metabolic and signaling activities. In addition to the re-acquisition of hepatocellular polarity, primary hepatocytes grown in collagen sandwich but not in monolayer culture recapitulated the apico-basal distribution of EEA1 endosomes observed in liver tissue. We found that such distribution correlated with the organization of the actin cytoskeleton in vitro and, surprisingly, was dependent on the nutritional state in vivo. Hepatocytes in collagen sandwich also exhibited faster kinetics of low-density lipoprotein (LDL) and epidermal growth factor (EGF) internalization, showed improved insulin sensitivity and preserved their ability for glucose production, compared to hepatocytes in monolayer cultures. Although no in vitro culture system can reproduce the exquisite structural features of liver tissue, our data nevertheless highlight the ability of the collagen sandwich system to recapitulate key structural and functional properties of the hepatocytes in the liver and, therefore, support the usage of this system to study aspects of hepatocellular biology in vitro.