The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Louise E Donnelly - One of the best experts on this subject based on the ideXlab platform.
-
altered scavenger receptor expression and response to oxidative stress is linked to defective bacterial Phagocytosis in copd macrophages
European Respiratory Journal, 2016Co-Authors: Kylie B R Belchamber, Peter J Barnes, Louise E DonnellyAbstract:Alveolar macrophages (Mφ) from COPD patients show defective bacterial Phagocytosis, which may be linked to increased oxidative stress in the lungs. Scavenger receptors mediate Phagocytosis, but may become damaged by oxidative stress. In this study, the effect oxidative stress on Phagocytosis and cell surface receptor expression was studied in monocyte-derived Mφ (MDM). MDM from non-smokers (NS), smokers (S) or COPD patients were cultured in GM-CSF for 12 d (n=5-7), then treated ± 200µM H 2 O 2 for 24h. MDM were exposed to fluorescently labelled H.influenzae (HI) or S.pneumoniae (SP) for 4 h, labelled with antibodies for HLA-DR, CD36, CD80, CD163, CD206, α v β 3 and ICAM-3, and analysed by flow cytometry. At baseline, COPD MDM expressed 68% less HLA-DR compared to NS (p v β 3 (NS 354%, S 313%, p 2 0 2 decreased Phagocytosis of HI (NS 35%, S 16%, COPD 17% p 2 0 2 caused a decrease in ICAM-3 expression after HI Phagocytosis (37% p MDM from COPD patients display differential scavenger receptor profiles compared to healthy MDM in response to Phagocytosis of bacteria. This could contribute to Mφ dysfunction in COPD. Exogenous oxidative stress decreased Phagocytosis in all patient groups, which may be linked to decreased expression of ICAM-3. Identifying the mechanisms involved in receptor expression may prove advantageous in developing novel therapies.
Silvia C Finnemann - One of the best experts on this subject based on the ideXlab platform.
-
Regulation of Phagocytosis by Rho GTPases.
Small GTPases, 2015Co-Authors: Silvia C FinnemannAbstract:Phagocytosis is defined as a cellular uptake pathway for particles of greater than 0.5 μm in diameter. Particle clearance by Phagocytosis is of critical importance for tissue health and homeostasis. The ultimate goal of anti-pathogen Phagocytosis is to destroy engulfed bacteria or fungi and to stimulate cell-cell signaling that mount an efficient immune defense. In contrast, clearance Phagocytosis of apoptotic cells and cell debris is anti-inflammatory. High capacity clearance Phagocytosis pathways are available to professional phagocytes of the immune system and the retina. Additionally, a low capacity, so-called bystander phagocytic pathway is available to most other cell types. Different phagocytic pathways are stimulated by particle ligation of distinct surface receptors but all forms of Phagocytosis require F-actin recruitment beneath tethered particles and F-actin re-arrangement promoting engulfment, which are controlled by Rho family GTPases. The specificity of Rho GTPase activity during the differ...
-
understanding photoreceptor outer segment Phagocytosis use and utility of rpe cells in culture
Experimental Eye Research, 2014Co-Authors: Francesca Mazzoni, Hussein Safa, Silvia C FinnemannAbstract:RPE cells are the most actively phagocytic cells in the human body. In the eye, RPE cells face rod and cone photoreceptor outer segments at all times but contribute to shedding and clearance Phagocytosis of distal outer segment tips only once a day. Analysis of RPE Phagocytosis in situ has succeeded in identifying key players of the RPE phagocytic mechanism. Phagocytic processes comprise three distinct phases, recognition/binding, internalization, and digestion, each of which is regulated separately by phagocytes. Studies of Phagocytosis by RPE cells in culture allow specifically analyzing and manipulating these distinct phases to identify their molecular mechanisms. Here, we compare similarities and differences of primary, immortalized, and stem cell-derived RPE cells in culture to RPE cells in situ with respect to phagocytic function. We discuss in particular potential pitfalls of RPE cell culture Phagocytosis assays. Finally, we point out considerations for Phagocytosis assay development for future studies.
Nicolas G. Bazan - One of the best experts on this subject based on the ideXlab platform.
-
photoreceptor outer segment Phagocytosis attenuates oxidative stress induced apoptosis with concomitant neuroprotectin d1 synthesis
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Pranab K. Mukherjee, Juan Carlos De Rivero Vaccari, Fannie E Jackson, Victor L Marcheselli, William C. Gordon, Nicolas G. BazanAbstract:Photoreceptor cell (rods and cones) renewal is accompanied by intermittent shedding of the distal tips of the outer segment followed by their Phagocytosis in the retinal pigment epithelial (RPE) cells. This renewal is essential for vision, and it is thought that it fosters survival of photoreceptors and of RPE cells. However, no specific survival messenger/mediators have as yet been identified. We show here that photoreceptor outer segment (POS) Phagocytosis markedly attenuates oxidative stress-induced apoptosis in ARPE-19 cells in culture. This phenomenon does not seem to be a generalized outcome of Phagocytosis because nonbiological (polystyrene microsphere) Phagocytosis did not elicit protection. The free docosahexaenoic acid (DHA) pool size and neuroprotectin D1 (NPD1) content increased during POS Phagocytosis but not during microspheres Phagocytosis. We have also explored other lipid mediators [lipoxin A4 and 15(S)- and 12(S)-hydroxyeicosatetraenoic acids] under these conditions and found them unchanged upon POS Phagocytosis. Moreover, oxidative stress challenge to RPE cells undergoing POS Phagocytosis further increased DHA and NPD1 content. Under these conditions, NPD1 was found within the RPE cells as well as in the culture medium, suggesting autocrine and paracrine bioactivity. Furthermore, using deuterium-labeled DHA, we show that as the availability of free DHA increases during oxidative stress, NPD1 synthesis is augmented in ARPE-19 cells. Our data suggest a distinct signaling that promotes survival of photoreceptor and RPE cells by enhancing the synthesis of NPD1 during Phagocytosis. Taken together, NPD1 may be a mediator that promotes homeostatic regulation of cell integrity during photoreceptor cell renewal.
Kylie B R Belchamber - One of the best experts on this subject based on the ideXlab platform.
-
altered scavenger receptor expression and response to oxidative stress is linked to defective bacterial Phagocytosis in copd macrophages
European Respiratory Journal, 2016Co-Authors: Kylie B R Belchamber, Peter J Barnes, Louise E DonnellyAbstract:Alveolar macrophages (Mφ) from COPD patients show defective bacterial Phagocytosis, which may be linked to increased oxidative stress in the lungs. Scavenger receptors mediate Phagocytosis, but may become damaged by oxidative stress. In this study, the effect oxidative stress on Phagocytosis and cell surface receptor expression was studied in monocyte-derived Mφ (MDM). MDM from non-smokers (NS), smokers (S) or COPD patients were cultured in GM-CSF for 12 d (n=5-7), then treated ± 200µM H 2 O 2 for 24h. MDM were exposed to fluorescently labelled H.influenzae (HI) or S.pneumoniae (SP) for 4 h, labelled with antibodies for HLA-DR, CD36, CD80, CD163, CD206, α v β 3 and ICAM-3, and analysed by flow cytometry. At baseline, COPD MDM expressed 68% less HLA-DR compared to NS (p v β 3 (NS 354%, S 313%, p 2 0 2 decreased Phagocytosis of HI (NS 35%, S 16%, COPD 17% p 2 0 2 caused a decrease in ICAM-3 expression after HI Phagocytosis (37% p MDM from COPD patients display differential scavenger receptor profiles compared to healthy MDM in response to Phagocytosis of bacteria. This could contribute to Mφ dysfunction in COPD. Exogenous oxidative stress decreased Phagocytosis in all patient groups, which may be linked to decreased expression of ICAM-3. Identifying the mechanisms involved in receptor expression may prove advantageous in developing novel therapies.
Janice M. Burke - One of the best experts on this subject based on the ideXlab platform.
-
photosensitized oxidative stress to arpe 19 cells decreases protein receptors that mediate photoreceptor outer segment Phagocytosis
Investigative Ophthalmology & Visual Science, 2013Co-Authors: Magdalena Olchawa, Anja Herrnreiter, Mariusz Zareba, Tadeusz Sarna, Christine M B Skumatz, Janice M. BurkeAbstract:Purpose. To determine whether previously shown photodynamic (PD)-induced inhibition of specific photoreceptor outer segment (POS) Phagocytosis by ARPE-19 cells is associated with reductions in receptor proteins mediating POS Phagocytosis, and if PD treatment with merocyanine-540 (MC-540) produces additional effects leading to its inhibition of nonspecific Phagocytosis.
