Cellular Microenvironment Stiffness Regulates Eicosanoid Production and Signaling Pathways.

Pathological changes in the biomechanical environment are implicated in the progression of idiopathic pulmonary fibrosis (IPF). Stiffened matrix augments fibroblast proliferation and differentiation and activates TGF-ß1 (transforming growth factor-ß1). Stiffened matrix impairs the synthesis of the antifibrogenic lipid mediator prostaglandin E2 (PGE2) and reduces the expression of the rate-limiting prostanoid biosynthetic enzyme cyclooxygenase-2 (COX-2). We now show that prostaglandin E synthase (PTGES), the final enzyme in the PGE2 biosynthetic pathway, is expressed at lower levels in the lungs of patients with IPF. We also show substantial induction of COX-2, PTGES, prostaglandin E receptor 4 (EP4), and cytosolic phospholipase A2 (cPLA2) expression in human lung fibroblasts cultured in soft collagen hydrogels or in spheroids compared with conventional culture on stiff plastic culture plates. Induction of COX-2, cPLA2, and PTGES expression in spheroid cultures was moderately inhibited by the p38 mitogen-activated protein kinase inhibitor SB203580. The induction of prostanoid biosynthetic enzyme expression was accompanied by an increase in PGE2 levels only in non-IPF-derived fibroblast spheroids. Our study reveals an extensive dysregulation of prostanoid biosynthesis and signaling pathways in IPF-derived fibroblasts, which are only partially abrogated by culture in soft microenvironments.

Localization of mercury and gold in cassava (Manihot esculenta Crantz).

The potential of cassava (Manihot esculenta Crantz.) for simultaneous Hg and Au phytoextraction was explored by investigating Hg and Au localization in cassava roots through Micro-Proton Induced X-Ray Emission, High-Resolution Transmission Electron Microscopy (HR-TEM) and X-Ray Diffractometry (XRD). The effect of Hg and Au in the cyanogenic glucoside linamarin distribution was also investigated using Matrix Assisted Laser Desorption Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (MALDI-FT-ICR-MS) imaging. Hg was located mainly in the root vascular bundle of plants grown in 50 or 100 µmol L-1 Hg solutions. Au was localized in the epidermis and cortex or in the epidermis and endodermis for 50 and 100 µmol L-1 Au solutions, respectively. For 50 µmol L-1 solutions of both Hg and Au, the two metals were co-localized in the epidermis. When the Hg concentrations were increased to 100 µmol L-1, Au was still localized to a considerable extent in the epidermis while Hg was located in all root parts. HR-TEM and XRD revealed that Au nanoparticles were formed in cassava roots. MALDI-FT-ICR-MS imaging showed linamarin distribution in the roots of control and plants and metal-exposed plants thus suggesting that linamarin might be involved in Hg and Au uptake and distribution.

Casein Kinase 1δ/ε Inhibitor, PF670462 Attenuates the Fibrogenic Effects of Transforming Growth Factor-ß in Pulmonary Fibrosis.

Transforming growth factor-beta (TGF-ß) is a major mediator of fibrotic diseases, including idiopathic pulmonary fibrosis (IPF). However, therapeutic global inhibition of TGF-ß is limited by unwanted immunosuppression and mitral valve defects. We performed an extensive literature search to uncover a little-known connection between TGF-ß signaling and casein kinase (CK) activity. We have examined the abundance of CK1 delta and epsilon (CK1δ/ε) in lung tissue from IPF patients and non-diseased controls, and investigated whether inhibition of CK1δ/ε with PF670462 inhibits pulmonary fibrosis. CK1δ/ε levels in lung tissue from IPF patients and non-diseased controls were assessed by immunohistochemistry. Anti-fibrotic effects of the CK1δ/ε inhibitor PF670462 were assessed in pre-clinical models, including acute and chronic bleomycin mouse models and in vitro experiments on spheroids made from primary human lung fibroblast cells from IPF and control donors, and human A549 alveolar-like adenocarcinoma-derived epithelial cells. Increased expression of CK1δ and ε in IPF lungs compared to non-diseased controls was accompanied by increased levels of the product, phospho-period 2. In vitro, PF670462 prevented TGF-ß-induced epithelial-mesenchymal transition. The stiffness of IPF-derived spheroids was reduced by PF670462 and TGF-ß-induced fibrogenic gene expression was inhibited. The CK1δ/ε inhibitor PF670462 administered systemically or locally by inhalation prevented both acute and chronic bleomycin-induced pulmonary fibrosis in mice. PF670462 administered in a 'therapeutic' regimen (day 7 onward) prevented bleomycin-induced lung collagen accumulation. Elevated expression and activity of CK1 δ and ε in IPF and anti-fibrogenic effects of the dual CK1δ/ε inhibitor, PF670462, support CK1δ/ε as novel therapeutic targets for IPF.

Transparent Silk Fibroin Microspheres from Controlled Droplet Dissolution in a Binary Solution.

Silk is a natural polymer with a broad range of potential applications in textiles, advanced materials, biomedical devices, and drug delivery. The ability to control the morphology and assembly of silk fibroin is essential for the fabrication of silk-based structured materials. Here, we report an effective and simple approach based on droplet dissolution for weaving silk fibroin into spheres of several hundred micrometers in diameter. The spheres possess regular wrinkled microstructures on the surface and switchable transparency for visible light. To produce these silk spheres, we immersed a sessile microdrop of the silk fibroin aqueous solution in a surrounding phase of ethanol in toluene at low concentration (<10%). The droplet experienced a two-phase process: the first phase of volume expansion due to the intake of organic solvents from the surrounding phase and the second phase of droplet dissolution. The dissolution rate is closely related to the dynamics of the droplet, while the resulting microstructure of the silk microsphere is simply adjusted by the composition of the surrounding solution. At high concentrations of ethanol, silk fibroin formed a thin shell around the droplet during the initial expansion of the droplet in volume. As the droplet shrank at a later stage, the shell around the droplet wrinkled and crumpled, leading to regular ridges and crevices on the microsphere surface. This work demonstrates that controlled droplet dissolution may be explored as a novel and effective way to tailor microstructures of silk assemblies. The as-prepared silk microspheres may be potentially used as optical units or microcarriers.

Dissolution dynamics of a suspension droplet in a binary solution for controlled nanoparticle assembly.

Toroidal microstructures of nanocolloidal assemblies promise important applications ranging from sensing, catalysis, drug delivery, and separation. In this work, we will first investigate the rich dissolution dynamics of a droplet comprising a nanoparticle suspension in a binary solution, and then show that the dissolution dynamics can be a potential approach to assembling a wide range of colloids with microtoroids. As the sessile droplet dissolves in the binary solution of miscible and immiscible solvents, two simultaneous effects are observed: if the dissolution rate is sufficiently high under large concentrations of the cosolvent in the surrounding solution, a strong plume emanates from the droplet pole as a consequence of a body force (i.e. the Korteweg force) driven by the chemical potential gradient between the water in the droplet and in the surrounding phase. Concurrently, the convection drives internal recirculation flow dynamics, leading to the inversion of the droplet curvature such that its initially spherical shape gradually contracts to evolve into a toroidal structure. We further demonstrate that the dissolution of a suspension droplet is an approach to assemble nanoparticles into toroidal microstructures. The resultant toroidal shapes are extrinsically governed by the composition and the geometrical confinement of the surrounding solution phase.

Confined self-assembly of cellulose nanocrystals in a shrinking droplet.

We have studied how cellulose nanocrystals (CNC) self-assemble into liquid crystalline phases in shrinking, isolated droplets. By adjusting the water dissolution rate of an aqueous CNC droplet immersed in a binary toluene-ethanol mixture we can control the final morphology of the consolidated microbead. At low ethanol concentration in the surrounding fluid dense microbeads of spherical morphology are produced while collapsed core-shell particles are obtained at high ethanol concentration. Polarized light microscopy was used to follow the spatial evolution and coalescence of birefringent spheroids during droplet shrinkage. Electron microscopy reveals the resultant nematic microstructure. This method of confined CNC assembly provides thus the possibility to prepare ordered microbeads, which can be useful as templates or for their optical properties.