BackgroundCigarette smoking is the major risk factor for COPD, leading to chronic airway inflammation. We hypothesized that cigarette smoke induces structural and functional changes of airway epithelial mitochondria, with important implications for lung inflammation and COPD pathogenesis.MethodsWe studied changes in mitochondrial morphology and in expression of markers for mitochondrial capacity, damage/biogenesis and fission/fusion in the human bronchial epithelial cell line BEAS-2B upon 6-months from ex-smoking COPD GOLD stage IV patients to age-matched smoking and never-smoking controls.ResultsWe observed that long-term CSE exposure induces robust changes in mitochondrial structure, including fragmentation, branching and quantity of cristae. The majority of these changes were persistent upon CSE depletion. Furthermore, long-term CSE exposure significantly increased the expression of specific fission/fusion markers (Fis1, Mfn1, Mfn2, Drp1 and Opa1), oxidative phosphorylation (OXPHOS) proteins (Complex II, III and V), and oxidative stress (Mn-SOD) markers. These changes were accompanied by increased levels of the pro-inflammatory mediators IL-6, IL-8, and IL-1β. Importantly, COPD primary bronchial epithelial cells (PBECs) displayed similar changes in mitochondrial morphology as observed in long-term CSE-exposure BEAS-2B cells. Moreover, expression of specific OXPHOS proteins was higher in PBECs from COPD patients than control smokers, as was the expression of mitochondrial stress marker PINK1.ConclusionThe observed mitochondrial changes in COPD epithelium are potentially the consequence of long-term exposure to cigarette smoke, leading to impaired mitochondrial function and may play a role in the pathogenesis of COPD.

A polarized layer of endothelial cells that comprises the blood-brain barrier (BBB) precludes access of systemically administered medicines to brain tissue. Consequently, there is a need for drug delivery vehicles that mediate transendothelial transport of such medicines. Endothelial cells use a variety of endocytotic pathways for the internalization of exogenous materials, including clathrin-mediated endocytosis, caveolar endocytosis, and macropinocytosis. The different modes of endocytosis result in the delivery of endocytosed material to distinctive intracellular compartments and therewith correlated differential processing. To obtain insight into the properties of drug delivery vehicles that direct their intracellular processing in brain endothelial cells, we investigated the intracellular processing of fixed-size nanoparticles in an in vitro BBB model as a function of distinct nanoparticle surface modifications. Caveolar endocytosis, adsorptive-mediated endocytosis, and receptor-mediated endocytosis were promoted by the use of uncoated 500-nm particles, attachment of the cationic polymer polyethyleneimine (PEI), and attachment of prion proteins, respectively. We demonstrate that surface modifications of nanoparticles, including charge and protein ligands, affect their mode of internalization by brain endothelial cells and thereby their subcellular fate and transcytotic potential.

The structure of the chorion and plasma membranes of gastrula‐stage zebrafish Brachydanio rerio embryos were studied using field emission scanning electron microscopy (FE‐SEM) and transmission electron microscopy (TEM). These studies confirm the outer chorion membrane complex to be 1.5–2.5 μm in thickness and to consist of three layers, electron‐dense outer and innermost layers (0.2–0.3 and 1.0–1.6 μm in thickness respectively) separated by an electron‐lucent middle layer (0.3–0.6 μm in thickness). The middle and inner layers are pierced by pore canals. A granular to farinaceous nature of the thin outer surface of the outer layer of the chorion has been revealed for the first time. The study provides original TEM images of the plasma membrane structures of gastrula‐stage embryos, and FE‐SEM and TEM images showing the plasma membrane to have three morpohologically distinct regions, being prominently ridged and folded at the surface of the blastoderm, smooth over the syncytial layer at the vegetal pole and with an intermediate region between the animal and vegetal pole where folding develops in advance of the expanding blastodermal disc of cells. FE‐SEM and TEM studies reveal details of the syncytial layer (1–4 μm thick) beneath the smooth plasma membrane at the vegetal pole, containing cytoplasmic organelles and small yolk globules. The significance of the structural detail shown in these studies is considered in the light of the difficulties experienced in cryopreservation of the embryo resulting from the inability of achieving cryoprotectant penetration of the yolk mass.

Using a mutant hepatocyte cell line in which E-cadherin and ␤-catenin are completely depleted from the cell surface, and, consequently, fail to form adherens junctions, we have investigated adherens junction requirement for apical-basolateral polarity development and polarized membrane trafficking. It is shown that these hepatocytes retain the capacity to form functional tight junctions, develop full apical-basolateral cell polarity, and assemble a subapical cortical F-actin network, although with a noted delay and a defect in subsequent apical lumen remodeling. Interestingly, whereas hepatocytes typically target the plasma membrane protein dipeptidyl peptidase IV first to the basolateral surface, followed by its transcytosis to the apical domain, hepatocytes lacking E-cadherin-based adherens junctions target dipeptidyl peptidase IV directly to the apical surface. Basolateral surface-directed transport of other proteins or lipids tested was not visibly affected in hepatocytes lacking E-cadherin-based adherens junctions. Together, our data show that E-cadherin/␤-cateninbased adherens junctions are dispensable for tight junction formation and apical lumen biogenesis but not for apical lumen remodeling. In addition, we suggest a possible requirement for E-cadherin/␤-catenin-based adherens junctions with regard to the indirect apical trafficking of specific proteins in hepatocytes.