Type II alveolar epithelial cells

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Interactions of 3 nm, 8 nm, and 15 nm gold particles with human alveolar epithelial cells : a microscopy study

Interactions of 3 nm, 8 nm, and 15 nm gold particles with human alveolar epithelial cells : a microscopy study

blebbing was observed. A time course of one blebbing cell with frame intervals of 3 sec was recorded. In Figure 45, the beginning of the image sequence is shown and blebbing was visible by the strong green membrane signal. Within the first 21 sec of image acquisition, ruffling of the cell membrane occurred and a vesicle was formed inside this region. The diameter of the vesicle was approx. 1.5 µm. Membrane ruffling is typical for an inefficient lamellipodia adhesion (Borm et al., 2005). After 2 min, the vesicle fused with a second vesicle (Figure 46). Another 2 min later, the newly formed compartment moved into a region aside from the ruffles (Figure 47).The morphology of the compartment changed from elongated to circular. Additionally, the vesicle increased in diameter, up to 3 µm, and did not move further after uptake. It only moved slightly back and forth, but stayed close to the perinuclear region. Frame 191 in Figure 47 was the last image of the recorded time series. Another two vesicles were generated from the membrane as indicated by the two smaller arrows in that image. Their diameter was 1 µm and slightly below the diameter of the first synthesized vesicle. Frame 191 in Figure 47 shows further that once vesicles have been internalized membrane blebbing disappeared and the cell showed again a normal morphology without any membrane ruffles or blebs. Some studies provide evidence that besides actin polymerization also polarized endo- and exocytic cycles can cause cell migration (Bretscher 1996a, 1996b) or even macropinocytosis (Gu et al., 2011), which could explain the vesicle formation at the leading edge of the cell. Hence, the live cell data indicated that the observed blebbing potentially could be attributed to lamellipodia formation. The type of the internalized vesicles could not be clarified within this experimental setup. However, the observed vesicle sizes of > 1 µm were similar to sizes known for macropinosomes (Mercer and Helenius 2009). These structures were usually formed at sites of membrane ruffling, e.g. margins of spread cells (Swanson and Watts 1995). Furthermore, type II alveolar epithelial cells, like A549 cells, synthesize LB that also have sizes of 0.1 - 2.4 µm, a circular morphology, and are able to fuse with the cell membrane (Schmitz and Müller 1991).
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Macrophage-epithelial crosstalk during alveolar epithelial repair following pathogen-induced pulmonary inflammation

Macrophage-epithelial crosstalk during alveolar epithelial repair following pathogen-induced pulmonary inflammation

Damage of the endo-epithelial barrier is the major hallmark of acute lung injury upon bacterial infection, associated with oedema formation, alveolar flooding, impaired fluid clearance and gas exchange. Hence, to restore the normal lung function, alveolar repair processes are ultimately initiated (34). Resident alveolar macrophages have been assigned a contributing role in epithelial repair, closely associated with the transition of the pro- inflammatory into the anti-inflammatory macrophage phenotype (62, 94). In the current thesis the potential of early activated, pro-inflammatory resident alveolar macrophages to influence epithelial repair processes was investigated. Moreover, the hypothesis that pro-inflammatory resident alveolar macrophages may contribute to effective epithelial repair after LPS- and K. pneumoniae induced lung injury was tested. Hence, in vitro experiments revealed that alveolar epithelial cells co-cultured with LPS-stimulated resident alveolar macrophages express significantly higher amounts of growth factors, particularly of GM-CSF. Macrophage TNF-α released upon LPS stimulation was identified as a mediator inducing GM-CSF expression in epithelial cells, which in turn elicited autocrine proliferative signalling in type II alveolar epithelial cells. Genetic deletion of GM-CSF resulted in absence of macrophage-induced epithelial cell proliferation. Similarly, in vivo TNF-α neutralization after LPS-induced lung injury impaired epithelial proliferation. Furthermore, GM-CSF-deficient mice displayed reduced AEC II proliferation and sustained alveolar leakage after LPS challenge. Similarly, K. pneumoniae-induced lung injury was associated with early release of TNF-α and GM-CSF, and subsequent TNF-α-dependent AEC II proliferation during the alveolar repair phase. Altogether, these data reveal that alveolar repair processes are initiated early in the inflammatory course of pathogen-induced acute lung injury, and are mediated by macrophage TNF-α and epithelial GM-CSF (Fig. 31).
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The Role of Alveolar Epithelial Type II-Like Cells in Uptake of Structurally Different Antigens and in Polarisation of Local Immune Responses

The Role of Alveolar Epithelial Type II-Like Cells in Uptake of Structurally Different Antigens and in Polarisation of Local Immune Responses

In vitro studies with lung cells revealed that both Bv1-Peptide and Bv1-Protein were taken up with the same intensity at all investigated time points (maximum uptake was detected after 6 hours, Fig 1 ), where around 15–20% of all cells were FAM + . In contrast, investigation of anti- gen uptake in vivo, after intranasal application, showed that Bv1-Peptide was internalised earli- er and more efficiently than Bv1-Protein in NALT and lungs ( Fig 3 ), however, only around 1 –2% of all cells were FAM + in the case of Bv1-Peptide and only around 0.5% in the case of Bv1-Protein. Moreover, Bv1-Peptide was internalised faster and at an earlier time point com- pared to Bv1-Protein. These data indicated that the size of the antigens might be an important factor for the effectivity and kinetic of the uptake. Accordingly, several studies investigated the relationship between increasing molecular weight and the effectivity of transport across the mucosal membrane in the respiratory tract and concluded an inverse relationship between molecule size and amount of antigen uptake [ 23 , 24 ]. Moreover, we observed differences in in- tensity of uptake between in vitro and in vivo conditions. The nasal respiratory epithelia is cov- ered with a constantly regenerating mucus, responsible for the fact that nasally-applied molecules are cleared from the mucosa within a short period (i.e. around 20 minutes) [ 23 ]. Thus, there is a narrow “window of opportunity” for antigens to be available for mucosal cells in comparison to in vitro conditions, where antigens are in the direct contact with cell popula- tions of the respiratory tract during the incubation period (i.e. 0.5 –48 hours).
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Role of CARM1 in regulation of alveolar epithelial senescence and emphysema susceptibility

Role of CARM1 in regulation of alveolar epithelial senescence and emphysema susceptibility

21 neutrophil elastase, were shown to be predisposed to an early onset of severe emphysema (67). A study on Pallid mice which are naturally deficient in AAT revealed that they suffered from an early development of emphysema compared to wild type mice with normal level of AAT (68, 69). Indeed, the imbalance may occur either by an unregulated excessive release of proteases or by a deficiency, reduced synthesis or increased breakdown of anti-proteases. The excessive proteolytic load is contributed by infiltrating phagocytic leukocytes, namely neutrophils and macrophages. These cells secrete a wide range of proteases, including serine proteases (neutrophil elastase, proteinase 3, cathepsin G), cysteine proteases (Cathepsins B, H, L, K and S) and a different types of matrix metalloproteases (MMPs) into emphysematous lungs (70-72). Among these, neutrophil elastase is a highly potent elastolytic enzyme and its intra-tracheal injection in experimental animals is capable of inducing emphysema (73). Another study demonstrated that mice lacking neutrophil elastase were 59% protected against emphysema (74). Secretory leukocyte protease inhibitor (SLPI) and elafin secreted by goblet cells, serus cells, Clara cells and alveolar type II (ATII) cells are both potent anti-proteases that can reversibly inhibit neutrophil elastase and in addition, SLPI can inhibit cathepsin G, trypsin, chymotrypsin and chymase while elafin inhibits proteinase-3 (72).
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Effects of -carotene and its cleavage products in primary pneumocyte type II cells

Effects of -carotene and its cleavage products in primary pneumocyte type II cells

oxidative burst [ 55 ]. As a consequence, particle-induced NO can react with the superoxide radical to form peroxynitrite [ 56 ], the homolysis of which generates the highly reactive OH-radical mediating tissue damage [ 57 ] via the initiation of lipid peroxidation. Similar to activated polymorphonuclear leukocytes [ 22 ], activated macrophages will cause the oxidative degradation of β-carotene and thus the formation of aldehydic and other breakdown products with different biological activities aggravating the impact of the oxidative burst. In fact, it has been demonstrated that β-carotene at a concentration that can be achieved in human plasma after chronic oral supplementation (5 µM) [ 58 ], and its metabolites were able to increase ~ OH formation from H 2 O 2 in the Fenton reaction and the addition of vitamin A and retinoic acid to lung epithelial cells co-cultured with activated neutrophils resulted in a significant increase of the level of oxidized purines [ 59 ], while the increase of oxidized purins was not significant after β-carotene treatment. These findings are in contrast to our findings with primary pneumocytes, as there was no indication of genotoxicity up to 10 µM. The question therefore arises as to whether DMNQ is an adequate model for oxidative stress in the lung. In this context, it has to be emphasized that DMNQ is an inducer of glutathione (GSH) [ 60 ], which is an essential element of the antioxidant defense [ 61 , 62 ]. GSH is the predominant scavenger of reactive oxygen species (ROS), particularly in the liver [ 62 ] and lung [ 63 ]. Under oxidative stress, the normal physiological ratio of ~100–1000 GSH:1 GSSG can be shifted toward the oxidized form, eventually even reaching an equimolar ratio [ 61 , 64 ]. GSSG is then exported out of the cells and metabolized [ 65 ]. Thus, relative levels of GSH and GSSG provide an efficient diagnostic option in judging the redox state of cells and hallmark oxidative stress, as demonstrated for several respiratory diseases and aging [ 62 , 66 ]. The lipid peroxidation product 4-hydroxynonenal is known to form adducts with GSH [ 67 ], and the immediate decrease of glutathione reported after smoking [ 54 , 68 ] can be attributed to this and other aldehydic lipid peroxidation products. While smoking significantly reduces cellular free glutathione (GSH) in experimental animals, especially in the lung, even after smoking periods as low as 30 days with exposures three times a day [ 69 ] DMNQ may eventually protect from oxidative damage. Therefore, the lack of an effect comparable to that found with primary hepatocytes [ 26 ] may relate to increased GSH levels in pneumocytes, and it can be assumed that co-cultivation of pneumocytes with alveolar macrophages or neutrophils, and subsequent activation will more realistically reflect the in vivo situation of smokers consuming β-carotene supplements.
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Primary and immortalized murine alveolar epithelial cells as novel in vitro systems for preclinical studies

Primary and immortalized murine alveolar epithelial cells as novel in vitro systems for preclinical studies

Alveolar epithelial cell lines are useful tools to study biochemical aspects of healthy and diseased conditions, but concurrently exhibit dedifferentiated characteristics like impaired tight junction providing only limited application for barrier-dependent investigations. As an example, the human alveolar type II-like cell line A549, derived from an adenocarcinoma, is widely applied for toxicity studies (Foldbjerg et al., 2011; Kreja & Seidel, 2002; Lestari et al., 2012) but lacks high TEER and is thus, not well suited for drug adsorption studies (Foster et al., 1998). The human alveolar type I-like cell line TT1 (‘transformed type-1’) was obtained through immortalization of primary ATII cells which were retrovirally transduced with hTERT and a temperature sensitive mutant of the Simian Virus 40 (SV40) large T antigen (Kemp et al., 2008; O'Hare et al., 2001). Immortalization methods and genes are addressed in the following chapter (see 1.3). In fact, TT1 cells have been used to study nanoparticle uptake (Kemp et al., 2008) as well as inflammatory responses and barrier properties (van den Bogaard et al., 2009). In the latter study, it was shown that TT1 did not develop high TEER limiting their applicability to barrier-independent experiments. This example illustrates that the genomic alterations upon cellular transduction might cause a loss of functional properties.
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TGF-beta impairs alveolar protein clearance through downregulation of the endocytic receptor megalin in alveolar epithelial cells

TGF-beta impairs alveolar protein clearance through downregulation of the endocytic receptor megalin in alveolar epithelial cells

Gas exchange takes place in the last seven generations of branching of the respiratory tract that include respiratory bronchioles, alveolar ducts and alveolar sacs and alveoli [12]. Airways and alveoli are lined by a continuous epithelium that provides secretive and absorptive functions. At the same time, it is a barrier for macromolecules but allows bidirectional flux of water, small solutes and gases [13]–[15]. In the most distal airways, the alveolar epithelium comprises two types of cells, thin squamous type I cells and cuboidal type II cells [12]. Alveolar type I cells (ATI) cover the major part of the surface area of distal airways and provide a pathway for diffusion of respiratory gases. On the other hand, ATII cells produce and secrete surfactant proteins, and together with ATI cells, actively participate in trans-epithelial transport of ions and proteins generating the driving force that allow fluid clearance from the alveolar space (Reviewed in [16]). Other important structures for the barrier function of the alveolar epithelium are the tight junctions. These cell-to-cell contact areas are flexible and selectively control passive movement of fluid and solutes between compartments. Thus tight junctions are critical in the maintenance of gradients created by active transport across the epithelium [17].
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MicroRNA profiling of purified alveolar epithelial type II cells from normal mice

MicroRNA profiling of purified alveolar epithelial type II cells from normal mice

For enzymatic digestion dispase was chosen. This enzyme specifically cleaves type IV collagen and fibronectin present within the ATII basement membrane (Stenn et al. 1989). Therefore, dispase is possibly more specific in releasing epithelial cells than other proteases while maintaining viability and cell characteristics (Corti et al. 1996). Agarose was instilled following enzyme placement to minimize Agarose-sensitive club cells (Harrison et al. 1995; Corti et al. 1996). Bronchoalveolar lavage was not performed as it could lead to dilution of dispase, diminishing enzyme activity (Corti et al. 1996), and further to lung injury with destruction and/or activation of AT II cells. In contrast to preparation of single cell suspension, no consensus exists on a protocol for the separation of ATII cells from the other lung cell populations in mice. Until now, many different procedures have been described to isolate ATII cells from mice including magnetic bead separation (Messier et al. 2012; Corti et al. 1996), “panning” using antibody-coated cell culture dishes (Rice et al. 2002; Königshoff 2009; Königshoff et al. 2009) and FACS (Fujino, Ota, Takahashi, et al. 2012; Gereke et al. 2012). ATII cells are difficult to isolate in high purities, because, first, extracellular ATII- specific markers for mice are rare and, second, labeling could change the activation status of purified cells. A combination of epithelial cell adhesion molecule (EpCAM) and T1 α protein antibody staining was used to isolate ATII cells by FACS as the EpCAM high /T1 α negative subpopulation in humans with 94.0% of purified cells expressing
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Type I interferon promotes alveolar epithelial type II cell survival during pulmonary inflammation / submitted by Barbara Maier

Type I interferon promotes alveolar epithelial type II cell survival during pulmonary inflammation / submitted by Barbara Maier

Here we demonstrate a protective role for IFN-I on epithelial cells in an inflammatory setting, which is likely to be mediated by interference with TNF signaling. This is a remarkable finding since it is well established that IFN-I executes pro-apoptotic or pro-pyroptotic functions in many cell types. In infectious settings it has been shown that inflammasome activation as well as IL-1 expression and processing are inhibited by IFN-I in the lung [120,122]. In tumor cells and virus infected cells IFN-I directly drives apoptosis via induction of different cellular mediators like TRAIL receptors, CD95, PKR or caspases [146]. IFN-I driven apoptosis can be an important factor in clearing virus infected cells, if only infected cells are targeted and if apoptosis is executed before the virus could spread to other cells. In the case of encephalomyocarditis virus (EMCV) infection IFN-I induced PKR regulates apoptosis which is an important mechanism to prevent the virus infection from fully establishing infection of different host sites [147]. The importance of IFN-I driven apoptosis in protecting from viral infections is also illustrated by the fact that many viruses have evolved strategies that counter-act apoptosis of host cells, for example the direct expression of viral proteins that block host PKR. In some malignancies IFN-I has been shown to promote survival of immune cells, as for example B-cells survival in chronic lymphocytic leukemia [148].
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Collagen vascular diseases associated with interstitial lung diseases : analysis of alveolar epithelial cellular stress mechanisms

Collagen vascular diseases associated with interstitial lung diseases : analysis of alveolar epithelial cellular stress mechanisms

Topoisomerases 2 (Topo2) generate transient double strand breaks in the DNA, ATP is required for this reaction. Topo2 is associated with gene promotor regions, which suggests, that they somehow play a role in transcription activation [97]. Topo2 can be subdivided in Topo2α and Topo2β, based on structural considerations. The precise roles of the two types are subject of current studies. Topo2α is essential for all cells and seems to play an important role in solving the topological problems associated with mitosis and replication [99]. The Topo2β-mediated, transient dsDNA break is required for activation of gene transcription by nuclear receptors and other classes of DNA binding transcription factors like activator protein 1 (AP-1). Furthermore it is suggested, that the dsDNA break formation, generated by Topo2β, creates a signal that leads to the activation of a poly[adenosine diphosphate (ADP)-ribose] polymerase 1 (PARP-1). PARP-1 is a nicotinamide adenide dinucleotide (NAD+)- dependent enzyme that detects and repairs damage to the DNA. Thus Topo2β probably regulates the initiation of ligand-or signal-dependant gene transcription [97].
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Macroautophagy substrates are loaded onto MHC class II of medullary thymic epithelial cells for central tolerance

Macroautophagy substrates are loaded onto MHC class II of medullary thymic epithelial cells for central tolerance

As immature DP thymocytes develop into mature SP thymocytes, cortical DP cells show an increased expression of the chemokine receptor CCR7 and transit from the cortex to the medulla 31 . CCR7 ligands, C-C motif chemokine (CCL)19 and CCL21, are predominantly produced by mTECs in the postnatal thymus 69, 70 . Therefore, thymocytes that receive TCR-mediated signals are attracted to the medulla through CCR7-mediated chemotaxis. Indeed, positively selected mature thymocytes are found in the cortex and central tolerance breaks down if the thymocyte homing pathway is blocked in CCR7- and CCR7 ligand-deficient mice 69 . Subsequent studies have shown that the thymic medulla has an indispensable role in negative selection. Intuitively, the medulla is the likely site for conducting negative selection, as it provides the most complex ligandome. To achieve successful negative selection, the thymus needs to present self-antigens that are expressed ubiquitously or are tissue-restricted. The medulla is heavily colonized by thymus-homing hematopoietic antigen presenting cells (APCs) capable of bringing ubiquitous antigens from the peripheral blood 71 . In addition, the main stromal cell subset residing in the medulla, mTECs, are capable of expressing a wide range of tissue restricted self-antigens (TRAs), which is termed as ‘promiscuous gene expression’. It has been estimated that around 2000–3000 TRAs are expressed by human and murine mTECs 72-74 .
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Targeting of autophagy by Yersinia enterocolitica in epithelial cells

Targeting of autophagy by Yersinia enterocolitica in epithelial cells

considerably lower rate than in wild-type cells, suggesting that autophagy supports bacterial replication, although it is not mandatorily required for the intracellular survival of the bacteria. This result differs from previous observations of our group that described the degradation of Y. enterocolitica in the autophagosomes of macrophages (Deuretzbacher et al. 2009). A possible explanation for this discrepancy could be that the autophagosome pathways taken by the YCVs vary depending on the cell type infected. Alternatively, the different methods used to impair autophagy in those cell lines could account for that difference. To inhibit autophagy in macrophages the inhibitor 3-methyladenine (3-MA) was applied to the cells before infection (Deuretzbacher et al. 2009). 3-MA blocks the class III PI3 kinase Vps34 which is part of the complex that mediates phagophore nucleation. However, this inhibitor, as most chemical inhibitors of autophagy, is not entirely specific and can to some extent also inhibit the class I PI3 kinase, leading to autophagy induction in some systems, as well as affect cell survival through AKT1 and other kinases (Klionsky et al. 2012). Accordingly, it is generally preferable to analyze specific loss of function effects in autophagy with atg mutant cells, as with the Atg5 -/- MEFs that we used in the present study. Lafont and colleagues studying Y. pseudotuberculosis in macrophages and HeLa cells (Moreau et al. 2010; Ligeon et al. 2014) also found that this bacterium can replicate in autophagic YCVs. However, and as mentioned before, LC3-positive Y. pseudotuberculosis-containing vacuoles show mainly single membrane structures in HeLa cells. Hence, interaction of Y. enterocolitica with the autophagy pathway may differ from the strategy employed by Y. pseudotuberculosis. We do neither know the reason underlying that discrepancy nor the consequences thereof but, even when Y. enterocolitica and Y. pseudotuberculosis are pathogens that cause very similar syndromes, the differences in the autophagic processes that they trigger could be related to different survival strategies developed by these pathogens due to distant evolution and pathogenicity of both bacteria (Wren 2003).
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Hypercapnia impairs cell junction formation by promoting TRAF2 E3 ligase-mediated ubiquitination and endocytosis of the Na,K-ATPase beta-subunit in alveolar epithelial cells

Hypercapnia impairs cell junction formation by promoting TRAF2 E3 ligase-mediated ubiquitination and endocytosis of the Na,K-ATPase beta-subunit in alveolar epithelial cells

In most polarized epithelial cells, the α- and β-subunit are expressed at an equimolar ratio, assembled as heterodimers, and delivered to the basolateral membrane where they contribute to active Na + transport and maintain epithelial integrity [65]. The abundance of Na + pump subunits and ATPase activity are tightly regulated by various stimuli. The pump is regulated by concentrations of its substrates as well as by changes in the molecular components of the surrounding environment (ions and non-ionic molecules). The Na,K- ATPase is modulated by membrane-associated components such as cytoskeletal elements and regulatory FXYD proteins, such as γ-subunit. The pump is also affected by variations in oxygen, carbon dioxide and nitrogen availability. As an important molecule in charge of various biological events, the Na,K-ATPase is regulated by a number of circulating endogenous inhibitors and hormones, such as aldosterone, thyroid hormone, glucocorticoid, catecholamines, insulin, carbachol, estrogen and androgen [34, 103-107]. All these stimuli can exert either short term or long term regulation of the Na, K-ATPase. Long term regulation of Na,K-ATPase usually involves changes in RNA and protein synthesis or degradation of the Na,K-ATPase isoforms [104, 107-111]. Short term modulation of the Na,K-ATPase function may be mediated by changes in the cellular distribution of pump units by reversible post-translational mechanisms such as phosphorylation or ubiquitination, or by changes in the intracellular Na + concentration which in turn modifies the pump kinetics [108, 111].
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Endosomal Organizers of post-Golgi trafficking in polarized epithelial cells

Endosomal Organizers of post-Golgi trafficking in polarized epithelial cells

Microtubule-based in vitro motility and binding assays allow to study interaction of motor proteins with cytoskeletal filaments and to characterize movement of purified organelles along microtubules. In the current study, in vitro assays have been used to adjust the vesicle immunoprecipitation procedure and to confirm the presence of molecular motors on purified vesicles, which were examined thereafter biochemically. In vitro binding assays have revealed first evidence that purified post-TGN vesicles carry proteins that form a link between a vesicle itself and a microtubule. Most probably, this interaction is carried out by motor proteins. In fact, the motility assay showed that the purified vesicles do not only bind to microtubules, but also move along them (Fig. 3.1). Remarkably is, that the vesicles were moving in both directions on microtubular tracks and this fact can have several explanations. First of all, bidirectional movement can be carried out by at least two types of motor proteins (plus and minus end-directed) present on the motile organelle. For example, this could be the plus end-directed kinesin and minus end-directed dynein, as in the case of in vitro reconstitution of ATP-dependent movement of endocytic vesicles (Murray et al., 2000). On the other hand, the normal diameter of a single microtubule is 25 nm, whereas the measured diameter of microtubules in the current assay was 100-200 nm (data not shown), which means that several microtubules could have formed a bundle, probably with even orientations of plus and minus ends. Thus, the vesicles were moving always in one direction (plus or minus), but they were changing the microtubular filament within the bundle. Another possibility for bidirectional movement is so called “diffusive” movement of motor proteins. This type of motion has been shown, for example, for kinesin-13, which uses a one- dimensional diffusive search to rapidly target microtubule ends where it binds and depolymerises microtubules (Helenius et al., 2006). Recently, diffusive in vitro movement has been demonstrated also for processive kinesin-1 (Lu et al., 2009).
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Characterization of bifidobacterial adhesion to intestinal epithelial cells

Characterization of bifidobacterial adhesion to intestinal epithelial cells

Mucus is secreted by goblet cells and consists of two layers: an inner layer (approximately 50 µm thick) firmly attached to the epithelium and a more loosely attached outer layer (100-500 µm thick) facing the intestinal lumen (Corazziari, 2009; Leser and Mølbak, 2009). Mucus is secreted at top of the crypts and then is pushed upwards along the crypt-villus axis by the newly secreted mucus underneath (Johansson et al., 2011). The tips of the villi are not always covered with mucus (Johansson et al., 2011). While some bacteria are able to colonize the outer layer, the inner firmly attached layer is devoid of bacteria (Atuma et al., 2001; Johansson et al., 2008). The main components of intestinal mucus are mucins, which are polymeric glycoproteins that are responsible for the gel-like structure (Hollingsworth and Swanson, 2004). Different mucins are expressed in an organ- specific manner with MUC2 being the predominant intestinal mucin. Some mucins, in particular MUC1, do not form polymers and stay covalently attached to the epithelium where they form the glycocalyx (Wilson, 2008). Other components of mucus are lipid vesicles, antibodies, ions, dietary products, entrapped microbes and water (Ofek et al., 2003).
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MicroRNA response to Listeria monocytogenes infection in epithelial cells

MicroRNA response to Listeria monocytogenes infection in epithelial cells

Recently, a role of miRNAs in the response against bacterial pathogens has been proposed. miRNAs were shown to be effective against Pseudomonas syringae infection in plants [8]. Similar to viruses, P. syringae was found to secrete proteins that bind host miRNA and subsequently modulate immune response [8]. Furthermore, Rao and colleagues described the presence miRNAs expressed by pathogenic Pseudomonas aeruginosa strains which were isolated from adult patients with cystic fibrosis [9]. Xiao et al. uncovered a Helicobacter pylori-dependent induction of miR-146b and miR-155 in gastric epithelial cells with subsequent inhibition of IL-8, a central cytokine in the chemotaxis of leukocytes [10]. Further investigation revealed that miRNAs control major inflammatory pathways, such as the TLR-mediated activation of the NF-kB pathway [10]. While P. syringae and H. pylori remain extracellular during infection, a recent study showed altered immune response of mice deficient in miR-155 to the facultative intracellular pathogen Salmonella [5]. Schulte et al. uncovered the regulation of IL-6 and IL-10 by miRNAs of the let-7 family and miR-155 induction by secreted effector proteins of Salmonella rather than the invading pathogen [5].
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Apoptose von Alveolar Typ II Epithelzellen nach stumpfem Thoraxtrauma - Rolle der Alveolarmakrophagen

Apoptose von Alveolar Typ II Epithelzellen nach stumpfem Thoraxtrauma - Rolle der Alveolarmakrophagen

Dieser Versuch wurde durchgeführt, um einerseits zu zeigen, dass löslicher Fas-Ligand Apoptose in AT2-Zellen, isoliert aus gesunden Sprague Dawley Ratten, auszulösen [r]

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Spraying Respiratory Epithelial Cells to Coat Tissue-Engineered Constructs

Spraying Respiratory Epithelial Cells to Coat Tissue-Engineered Constructs

good spray was already produced with a pressure of 0.4 bar. In general, next to the nozzle dimension, the pressure is a process parameter that is related to the shear the cells may experience during spray formation. Veazey et al. tested air pressures between 0.41 and 1.24 bar and showed a direct dependence of the survival of bovine dermal fibroblasts. 4 Similarly, Nahmias et al. re- port survival rates of NIH 3T3 cells of 64% at a pressure of 0.97 bar till 90% for a pressure less than 0.34 bar. 3 Tritz et al. have shown chondrocyte survival rates of 88% and 80% in alginate gels 3 days after spraying for pressures of 0.9 and 1.2 bar. 2 In another study, the same group reports a survival rate of 52% for human mesenchymal stem cells in the same setup with a pressure of 0.9 bar. 24 Roberts et al. report a chon- drocyte survival of 70–84% depending on air flow rates between 4 and 8 L/min (which corresponds to different air pressures as well). 6 Thus, higher pressures evoke higher shear and elongation stresses on the cells and re- duce their survival. Hence, the unchanged survival of vSMCs and 88.5% survival rate of our RECs at a pressure of 0.4 bar are very good results.
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Lymph-borne CD8α+ dendritic cells are uniquely able to cross-prime CD8+ T cells with antigen acquired from intestinal epithelial cells

Lymph-borne CD8α+ dendritic cells are uniquely able to cross-prime CD8+ T cells with antigen acquired from intestinal epithelial cells

non-lymphoid tissues. 21 Although we cannot rule out the possibility that some CD103 þ CD11b  CD8a þ LDCs originate in the lymphoid compartments of the intestine, it is likely that they largely represent LP-derived migratory DCs. Crucially, CD103 þ CD11b  CD8a þ DCs are also able to cross-present IEC antigen to CD8 þ T cells in vivo. By adapting a technique described by the Pabst laboratory, 29 we showed that subcapsular injection of CD103 þ CD11b  CD8a þ LDCs, but not other DC subsets, from the lymph of steady-state 232-4 mice into the MLNs led to clonal expansion of OT-I T cells. The capacity of intestinal DCs to induce gut tropism in a retinoic acid-dependent manner has been well character- ized. 24,30 However, it is not clear which intestinal DCs are primarily responsible for inducing this phenotype in CD8 þ T cells. In contrast with an earlier report, 11 we have recently shown that CD103 þ CD11b  CD8a þ DCs have high aldehyde dehydrogenase activity and can induce CCR9, a marker of gut tropism on T cells, with a similar efficiency to the other intestinal DC subsets. 10 Here we show that, in vivo, cross- presentation by CD103 þ CD11b  CD8a þ DCs also induces CCR9 expression on responding OT-I T cells, and that, in this experimental system, fully differentiated CCR9 þ OT-I cells are only detectable in the intestinal LP of mice after subcapsular injection of CD103 þ CD11b  CD8a þ LDCs, but not other LDC subsets.
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Plasticity of patient-matched normal mammary epithelial cells is dependent on autologous adipose-derived stem cells

Plasticity of patient-matched normal mammary epithelial cells is dependent on autologous adipose-derived stem cells

The concentration of ECM proteins in the ADSC secretome was nearly equal in all 5 patients, e.g. FN/ fibronectin and THBS1/thrombospondin-1. ADSC secretion of several types of ECM proteins 60 , supports adhe- sion and proliferation of MEC. Although, the ADSC secretome did not influence ECM COL4A1 and FN1 gene expression of NORMA MEC, the integrin receptors ITGA5/6 were induced. This supports ADSC mediated MEC ECM interactions are essential for development. Normal mammary breast tissue contains low levels of FN, com- pared to higher levels in breast tumors 61 . Recently, it could be shown that high FN concentration in breast tumors induce EMT and might be both, a cause and result of tumor initiation and/or progression 61 . In contrast, THBS1 is an ECM glycoprotein that inhibits tumor cell growth and metastasis partly due to its anti-angiogenic effect 62 . However, prolonged delivery of THBS1 can result in emerging resistant cells that lead to tumor insensitivity 62 .
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