1
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Ouderkirk S, Sedley A, Ong M, Shifflet MR, Harkrider QC, Wright NT, Miller CJ. A Perspective on Developing Modeling and Image Analysis Tools to Investigate Mechanosensing Proteins. Integr Comp Biol 2023; 63:1532-1542. [PMID: 37558388 PMCID: PMC10755202 DOI: 10.1093/icb/icad107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/17/2023] [Accepted: 07/17/2023] [Indexed: 08/11/2023] Open
Abstract
The shift of funding organizations to prioritize interdisciplinary work points to the need for workflow models that better accommodate interdisciplinary studies. Most scientists are trained in a specific field and are often unaware of the kind of insights that other disciplines could contribute to solving various problems. In this paper, we present a perspective on how we developed an experimental pipeline between a microscopy and image analysis/bioengineering lab. Specifically, we connected microscopy observations about a putative mechanosensing protein, obscurin, to image analysis techniques that quantify cell changes. While the individual methods used are well established (fluorescence microscopy; ImageJ WEKA and mTrack2 programs; MATLAB), there are no existing best practices for how to integrate these techniques into a cohesive, interdisciplinary narrative. Here, we describe a broadly applicable workflow of how microscopists can more easily quantify cell properties (e.g., perimeter, velocity) from microscopy videos of eukaryotic (MDCK) adherent cells. Additionally, we give examples of how these foundational measurements can create more complex, customizable cell mechanics tools and models.
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Affiliation(s)
- Stephanie Ouderkirk
- Department of Chemistry, James Madison University, Harrisonburg, VA 22807, USA
| | - Alex Sedley
- Department of Engineering, James Madison University, Harrisonburg, VA 22807, USA
| | - Mason Ong
- Department of Engineering, James Madison University, Harrisonburg, VA 22807, USA
| | - Mary Ruth Shifflet
- Department of Chemistry, Bridgewater College, Bridgewater, VA 22812, USA
| | - Quinn C Harkrider
- Department of Chemistry, James Madison University, Harrisonburg, VA 22807, USA
| | - Nathan T Wright
- Department of Chemistry, James Madison University, Harrisonburg, VA 22807, USA
| | - Callie J Miller
- Department of Engineering, James Madison University, Harrisonburg, VA 22807, USA
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2
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Abstract
The nasopharynx and the skin are the major oxygen-rich anatomical sites for colonization by the human pathogen Streptococcus pyogenes (group A Streptococcus [GAS]). To establish infection, GAS must survive oxidative stress generated during aerobic metabolism and the release of reactive oxygen species (ROS) by host innate immune cells. Glutathione is the major host antioxidant molecule, while GAS is glutathione auxotrophic. Here, we report the molecular characterization of the ABC transporter substrate binding protein GshT in the GAS glutathione salvage pathway. We demonstrate that glutathione uptake is critical for aerobic growth of GAS and that impaired import of glutathione induces oxidative stress that triggers enhanced production of the reducing equivalent NADPH. Our results highlight the interrelationship between glutathione assimilation, carbohydrate metabolism, virulence factor production, and innate immune evasion. Together, these findings suggest an adaptive strategy employed by extracellular bacterial pathogens to exploit host glutathione stores for their own benefit.
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3
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Structural Configuration of Blood Cell Membranes Determines Their Nonlinear Deformation Properties. BIOMED RESEARCH INTERNATIONAL 2022; 2022:1140176. [PMID: 35480142 PMCID: PMC9038403 DOI: 10.1155/2022/1140176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 02/07/2022] [Accepted: 02/22/2022] [Indexed: 11/17/2022]
Abstract
The ability of neutrophils and red blood cells (RBCs) to undergo significant deformations is a key to their normal functioning. Disruptions of these processes can lead to pathologies. This work studied the influence of structural configuration rearrangements of membranes after exposure to external factors on the ability of native membranes of neutrophils and RBCs to undergo deep deformation. The rearrangement of the structural configuration of neutrophil and RBC membranes under the influence of cytological fixatives caused nonlinear deformation phenomena. There were an increase in Young's modulus, a decrease in the depth of homogeneous bending, and a change in the distance between cytoskeletal junctions. Based on the results of the analysis of experimental data, a mathematical model was proposed that describes the process of deep bending of RBСs and neutrophil membranes.
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Johnson CL, Riley L, Bersi M, Linton MF, Merryman WD. Impaired macrophage trafficking and increased helper T-cell recruitment with loss of cadherin-11 in atherosclerotic immune response. Am J Physiol Heart Circ Physiol 2021; 321:H756-H769. [PMID: 34506228 PMCID: PMC8794229 DOI: 10.1152/ajpheart.00263.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 08/30/2021] [Accepted: 08/30/2021] [Indexed: 12/11/2022]
Abstract
Inflammation caused by infiltrating macrophages and T cells promotes plaque growth in atherosclerosis. Cadherin-11 (CDH11) is a cell-cell adhesion protein implicated in several fibrotic and inflammatory diseases. Much of the research on CDH11 concerns its role in fibroblasts, although its expression in immune cells has been noted as well. The objective of this study was to assess the effect of CDH11 on the atherosclerotic immune response. In vivo studies of atherosclerosis indicated an increase in Cdh11 in plaque tissue. However, global loss of Cdh11 resulted in increased atherosclerosis and inflammation. It also altered the immune response in circulating leukocytes, decreasing myeloid cell populations and increasing T-cell populations, suggesting possible impaired myeloid migration. Bone marrow transplants from Cdh11-deficient mice resulted in similar immune cell profiles. In vitro examination of Cdh11-/- macrophages revealed reduced migration, despite upregulation of a number of genes related to locomotion. Flow cytometry revealed an increase in CD3+ and CD4+ helper T-cell populations in the blood of both the global Cdh11 loss and the bone marrow transplant animals, possibly resulting from increased expression by Cdh11-/- macrophages of major histocompatibility complex class II molecule genes, which bind to CD4+ T cells for coordinated activation. CDH11 fundamentally alters the immune response in atherosclerosis, resulting in part from impaired macrophage migration and altered macrophage-induced T-cell activation.NEW & NOTEWORTHY Cadherin-11 is well known to contribute to inflammatory and fibrotic disease. Here, we examined its role in atherosclerosis progression, which is predominantly an inflammatory process. We found that while cadherin-11 is associated with plaque progression, global loss of cadherin-11 exacerbated the disease phenotype. Moreover, loss of cadherin-11 in bone marrow-derived immune cells resulted in impaired macrophage migration and an unexplained increase in circulating helper T cells, presumably due to altered macrophage function without cadherin-11.
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Grants
- F32 HL154596 NHLBI NIH HHS
- R00 HL146951 NHLBI NIH HHS
- HL148137 HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- R01 HL127173 NHLBI NIH HHS
- HL127173 HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- HL135790 HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- DK059637 HHS | NIH | National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
- K99 HL146951 NHLBI NIH HHS
- HL146951 HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- P01 HL116263 NHLBI NIH HHS
- R35 HL135790 NHLBI NIH HHS
- R01 HL148137 NHLBI NIH HHS
- R01 HL146134 NHLBI NIH HHS
- HL146134 HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- U24 DK059637 NIDDK NIH HHS
- HL154596 HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- HL116263 HHS | NIH | National Heart, Lung, and Blood Institute (NHLBI)
- American Heart Association (AHA)
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Affiliation(s)
- Camryn L Johnson
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Lance Riley
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Matthew Bersi
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - MacRae F Linton
- Atherosclerosis Research Unit, Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee
| | - W David Merryman
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
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Wang X, Deb N, Lacerda CMR. Comparison of Serotonin-Regulated Calcific Processes in Aortic and Mitral Valvular Interstitial Cells. ACS OMEGA 2021; 6:19494-19505. [PMID: 34368536 PMCID: PMC8340088 DOI: 10.1021/acsomega.1c01723] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/28/2021] [Indexed: 06/13/2023]
Abstract
Calcification is an important pathological process and a common complication of degenerative valvular heart diseases, with higher incidence in aortic versus mitral valves. Two phenotypes of valvular interstitial cells (VICs), activated VICs and osteoblastic VICs (obVICs), synergistically orchestrate this pathology. It has been demonstrated that serotonin is involved in early stages of myxomatous mitral degeneration, whereas the role of serotonin in calcific aortic valve disease is still unknown. To uncover the link between serotonin and osteogenesis in heart valves, osteogenesis of aortic and mitral VICs was induced in vitro. Actin polymerization and serotonin signaling were inhibited using cytochalasin D and serotonin inhibitors, respectively, to investigate the role of cell activation and serotonin signals in valvular cell osteogenesis. To evaluate calcification progress, calcium and collagen deposits along with the expression of protein markers, including the rate-limiting enzyme of serotonin synthesis [tryptophan hydroxylase 1 (TPH1)], were assessed. When exposed to osteogenic culture conditions and grown on soft surfaces, passage zero aortic VICs increased extracellular collagen deposits and obVIC phenotype markers. A more intense osteogenic process was observed in aortic VICs of higher passages, where cells were activated prior to osteogenic induction. For both, TPH1 expression was upregulated as osteogenesis advanced. However, these osteogenic changes were reversed upon serotonin inhibition. This discovery provides a better understanding of signaling pathways regulating VIC phenotype transformation and explains different manifestations of degenerative pathologies. In addition, the discovery of serotonin-based inhibition of valvular calcification will contribute to the development of potential novel therapies for calcific valvular diseases.
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Affiliation(s)
- Xinmei Wang
- Department
of Bioengineering, Shenyang University, Shenyang, Liaoning 110044, China
| | - Nandini Deb
- Department
of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409-3121, United States
| | - Carla M. R. Lacerda
- Department
of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409-3121, United States
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Activation of NLRP3 by uropathogenic Escherichia coli is associated with IL-1β release and regulation of antimicrobial properties in human neutrophils. Sci Rep 2020; 10:21837. [PMID: 33318544 PMCID: PMC7736892 DOI: 10.1038/s41598-020-78651-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 11/26/2020] [Indexed: 02/06/2023] Open
Abstract
The NLRP3 inflammasome and IL-1β have recently been linked to the severity of uropathogenic Escherichia coli (UPEC)-mediated urinary tract infection (UTI). However, not much is known about the contribution of NLRP3 to the antimicrobial properties of neutrophils and the release of IL-1β during UPEC infection. The purpose of this study was to elucidate the mechanisms behind UPEC-induced IL-1β release from human neutrophils, and to investigate the contribution of the NLRP3 inflammasome in neutrophil-mediated inhibition of UPEC growth. We found that the UPEC strain CFT073 increased the expression of NLRP3 and increased caspase-1 activation and IL-1β release from human neutrophils. The IL-1β release was mediated by the NLRP3 inflammasome and by serine proteases in an NF-κB-and cathepsin B-dependent manner. The UPEC virulence factors α-hemolysin, type-1 fimbriae and p-fimbriae were all shown to contribute to UPEC mediated IL-1β release from neutrophils. Furthermore, inhibition of caspase-1 and NLRP3 activation increased neutrophil ROS-production, phagocytosis and the ability of neutrophils to suppress UPEC growth. In conclusion, this study demonstrates that UPEC can induce NLRP3 and serine protease-dependent release of IL-1β from human neutrophils and that NLRP3 and caspase-1 can regulate the antimicrobial activity of human neutrophils against UPEC.
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Dahmke IN, Trampert P, Weinberg F, Mostajeran Z, Lautenschläger F, de Jonge N. Correlative Fluorescence- and Electron Microscopy of Whole Breast Cancer Cells Reveals Different Distribution of ErbB2 Dependent on Underlying Actin. Front Cell Dev Biol 2020; 8:521. [PMID: 32714928 PMCID: PMC7344305 DOI: 10.3389/fcell.2020.00521] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 06/02/2020] [Indexed: 12/26/2022] Open
Abstract
Epidermal growth factor receptor 2 (ErbB2) is found overexpressed in several cancers, such as gastric, and breast cancer, and is, therefore, an important therapeutic target. ErbB2 plays a central role in cancer cell invasiveness, and is associated with cytoskeletal reorganization. In order to study the spatial correlation of single ErbB2 proteins and actin filaments, we applied correlative fluorescence microscopy (FM), and scanning transmission electron microscopy (STEM) to image specifically labeled SKBR3 breast cancer cells. The breast cancer cells were grown on microchips, transformed to express an actin-green fluorescent protein (GFP) fusion protein, and labeled with quantum dot (QD) nanoparticles attached to specific anti-ErbB2 Affibodies. FM was performed to identify cellular regions with spatially correlated actin and ErbB2 expression. For STEM of the intact plasma membrane of whole cells, the cells were fixed and covered with graphene. Spatial distribution patterns of ErbB2 in the actin rich ruffled membrane regions were examined, and compared to adjacent actin-low regions of the same cell, revealing an association of putative signaling active ErbB2 homodimers with actin-rich regions. ErbB2 homodimers were found absent from actin-low membrane regions, as well as after treatment of cells with Cytochalasin D, which breaks up larger actin filaments. In both latter data sets, a significant inter-label distance of 36 nm was identified, possibly indicating an indirect attachment to helical actin filaments via the formation of heterodimers of ErbB2 with epidermal growth factor receptor (EGFR). The possible attachment to actin filaments was further explored by identifying linear QD-chains in actin-rich regions, which also showed an inter-label distance of 36 nm.
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Affiliation(s)
| | - Patrick Trampert
- German Research Center for Artificial Intelligence, Saarbrücken, Germany
| | | | | | - Franziska Lautenschläger
- INM – Leibniz Institute for New Materials, Saarbrücken, Germany
- Department of Physics, Saarland University, Saarbrücken, Germany
| | - Niels de Jonge
- INM – Leibniz Institute for New Materials, Saarbrücken, Germany
- Department of Physics, Saarland University, Saarbrücken, Germany
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8
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Kwon S, Kim KS. Qualitative analysis of contribution of intracellular skeletal changes to cellular elasticity. Cell Mol Life Sci 2020; 77:1345-1355. [PMID: 31605149 PMCID: PMC11105102 DOI: 10.1007/s00018-019-03328-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 09/25/2019] [Accepted: 09/30/2019] [Indexed: 01/07/2023]
Abstract
Cells are dynamic structures that continually generate and sustain mechanical forces within their environments. Cells respond to mechanical forces by changing their shape, moving, and differentiating. These reactions are caused by intracellular skeletal changes, which induce changes in cellular mechanical properties such as stiffness, elasticity, viscoelasticity, and adhesiveness. Interdisciplinary research combining molecular biology with physics and mechanical engineering has been conducted to characterize cellular mechanical properties and understand the fundamental mechanisms of mechanotransduction. In this review, we focus on the role of cytoskeletal proteins in cellular mechanics. The specific role of each cytoskeletal protein, including actin, intermediate filaments, and microtubules, on cellular elasticity is summarized along with the effects of interactions between the fibers.
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Affiliation(s)
- Sangwoo Kwon
- Department of Biomedical Engineering, College of Medicine, Kyung Hee University, 1 Hoegi-dong, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| | - Kyung Sook Kim
- Department of Biomedical Engineering, College of Medicine, Kyung Hee University, 1 Hoegi-dong, Dongdaemun-gu, Seoul, 02447, Republic of Korea.
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9
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Lin H, Singla B, Ghoshal P, Faulkner JL, Cherian‐Shaw M, O'Connor PM, She J, Belin de Chantemele EJ, Csányi G. Identification of novel macropinocytosis inhibitors using a rational screen of Food and Drug Administration-approved drugs. Br J Pharmacol 2018; 175:3640-3655. [PMID: 29953580 PMCID: PMC6109223 DOI: 10.1111/bph.14429] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 05/08/2018] [Accepted: 06/13/2018] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND AND PURPOSE Macropinocytosis is involved in many pathologies, including cardiovascular disorders, cancer, allergic diseases, viral and bacterial infections. Unfortunately, the currently available pharmacological inhibitors of macropinocytosis interrupt other endocytic processes and have non-specific endocytosis-independent effects. Here we have sought to identify new, clinically relevant inhibitors of macropinocytosis, using an FDA-approved drug library. EXPERIMENTAL APPROACH In the present study, 640 FDA-approved compounds were tested for their ability to inhibit macropinocytosis. A series of secondary assays were performed to confirm inhibitory activity, determine IC50 values and investigate cell toxicity. The ability of identified hits to inhibit phagocytosis and clathrin-mediated and caveolin-mediated endocytosis was also investigated. Scanning electron microscopy and molecular biology techniques were utilized to examine the mechanisms by which selected compounds inhibit macropinocytosis. KEY RESULTS The primary screen identified 14 compounds that at ~10 μM concentration inhibit >95% of macropinocytotic solute internalization. Three compounds - imipramine, phenoxybenzamine and vinblastine - potently inhibited (IC50 ≤ 131 nM) macropinocytosis without exerting cytotoxic effects or inhibiting other endocytic pathways. Scanning electron microscopy imaging indicated that imipramine inhibits membrane ruffle formation, a critical early step leading to initiation of macropinocytosis. Finally, imipramine has been shown to inhibit macropinocytosis in several cell types, including cancer cells, dendritic cells and macrophages. CONCLUSIONS AND IMPLICATIONS Our results identify imipramine as a new pharmacological tool to study macropinocytosis in cellular and biological systems. This study also suggests that imipramine could be a good candidate for repurposing as a therapeutic agent in pathological processes involving macropinocytosis.
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Affiliation(s)
- Hui‐Ping Lin
- Vascular Biology CenterAugusta UniversityAugustaGAUSA
| | | | | | | | | | | | - Jin‐Xiong She
- Center for Biotechnology and Genomic MedicineAugusta UniversityAugustaGAUSA
| | | | - Gábor Csányi
- Vascular Biology CenterAugusta UniversityAugustaGAUSA
- Department of Pharmacology and ToxicologyAugusta UniversityAugustaGAUSA
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10
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Nyberg KD, Hu KH, Kleinman SH, Khismatullin DB, Butte MJ, Rowat AC. Quantitative Deformability Cytometry: Rapid, Calibrated Measurements of Cell Mechanical Properties. Biophys J 2017; 113:1574-1584. [PMID: 28978449 DOI: 10.1016/j.bpj.2017.06.073] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 06/14/2017] [Accepted: 06/29/2017] [Indexed: 11/29/2022] Open
Abstract
Advances in methods that determine cell mechanical phenotype, or mechanotype, have demonstrated the utility of biophysical markers in clinical and research applications ranging from cancer diagnosis to stem cell enrichment. Here, we introduce quantitative deformability cytometry (q-DC), a method for rapid, calibrated, single-cell mechanotyping. We track changes in cell shape as cells deform into microfluidic constrictions, and we calibrate the mechanical stresses using gel beads. We observe that time-dependent strain follows power-law rheology, enabling single-cell measurements of apparent elastic modulus, Ea, and power-law exponent, β. To validate our method, we mechanotype human promyelocytic leukemia (HL-60) cells and thereby confirm q-DC measurements of Ea = 0.53 ± 0.04 kPa. We also demonstrate that q-DC is sensitive to pharmacological perturbations of the cytoskeleton as well as differences in the mechanotype of human breast cancer cell lines (Ea = 2.1 ± 0.1 and 0.80 ± 0.19 kPa for MCF-7 and MDA-MB-231 cells). To establish an operational framework for q-DC, we investigate the effects of applied stress and cell/pore-size ratio on mechanotype measurements. We show that Ea increases with applied stress, which is consistent with stress stiffening behavior of cells. We also find that Ea increases for larger cell/pore-size ratios, even when the same applied stress is maintained; these results indicate strain stiffening and/or dependence of mechanotype on deformation depth. Taken together, the calibrated measurements enabled by q-DC should advance applications of cell mechanotype in basic research and clinical settings.
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Affiliation(s)
- Kendra D Nyberg
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California; Department of Bioengineering, University of California, Los Angeles, California
| | - Kenneth H Hu
- Department of Physics, Stanford University, Stanford, California
| | - Sara H Kleinman
- Department of Pediatrics, Stanford University, Stanford, California
| | | | - Manish J Butte
- Department of Pediatrics, University of California, Los Angeles, California; Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California
| | - Amy C Rowat
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California; Department of Bioengineering, University of California, Los Angeles, California; UCLA Jonsson Comprehensive Cancer Center, University of California, Los Angeles, California; Broad Stem Cell Research Center, University of California, Los Angeles, California; Center for Biological Physics, University of California, Los Angeles, California.
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11
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Kuznetsova T, Kulahava T, Zholnerevich I, Amaegberi N, Semenkova G, Shadyro O, Arnhold J. Morphometric characteristics of neutrophils stimulated by adhesion and hypochlorite. Mol Immunol 2017; 87:317-324. [PMID: 28544986 DOI: 10.1016/j.molimm.2017.05.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 04/03/2017] [Accepted: 05/06/2017] [Indexed: 11/18/2022]
Abstract
The aim of this work was to compare cell form, size and volume as well as the locomotor activity of polymorphonuclear leukocytes (PMNLs) stimulated by adhesion to glass and exposed to hypochlorous acid at non-toxic dose. After 20min of adhesion to a glass surface, volume, cell surface area and projection area of PMNLs were equaled to 143.1±21.4μm3, 288.8±28.8μm2 and 248.3±32.3μm2, respectively. Projection area of PMNLs exposed to NaOCl was noticeably enlarged as compared with control samples. The cell volume of 20min adherent cells exposed to NaOCl was enlarged in comparison with both control cells and 5min adhered exposed to NaOCl cells. NaOCl exposure induced a degranulation of PMNLs as measured by lysozyme release. Granules could be found both above the cell surface and on the substratum near the cell. The S/V ratio for PMNLs increased (from 1.52 to 2.02μm-1) with the increasing of cell activation time. But at NaOCl addition the reverse tendency was observed (from 2.10 to 1.87μm-1). In cells exposed to NaOCl the redistribution and decrease of concentration of F-actin took place. This observation supports the hypothesis that the priming of PMNLs with hypochlorous acid modifies cell motility and morphology and reflects also on other functions.
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Affiliation(s)
- Tatsiana Kuznetsova
- N.I. Pirogov Russian National Research Medical University, Moscow, Russian Federation.
| | - Tatsiana Kulahava
- Department of Biophysics, Faculty of Physics, Belarusian State University, Minsk, Belarus.
| | - Ivan Zholnerevich
- Department of Biophysics, Faculty of Physics, Belarusian State University, Minsk, Belarus.
| | - Nadezda Amaegberi
- Department of Radiation Chemistry and Pharmaceutical Technologies, Faculty of Chemistry, Belarusian State University, Minsk, Belarus.
| | - Galina Semenkova
- Department of Radiation Chemistry and Pharmaceutical Technologies, Faculty of Chemistry, Belarusian State University, Minsk, Belarus.
| | - Oleg Shadyro
- Department of Radiation Chemistry and Pharmaceutical Technologies, Faculty of Chemistry, Belarusian State University, Minsk, Belarus.
| | - Juergen Arnhold
- Institute for Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Leipzig, Germany.
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12
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Hyperspectral Imaging Using Intracellular Spies: Quantitative Real-Time Measurement of Intracellular Parameters In Vivo during Interaction of the Pathogenic Fungus Aspergillus fumigatus with Human Monocytes. PLoS One 2016; 11:e0163505. [PMID: 27727286 PMCID: PMC5058474 DOI: 10.1371/journal.pone.0163505] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 09/09/2016] [Indexed: 12/14/2022] Open
Abstract
Hyperspectral imaging (HSI) is a technique based on the combination of classical spectroscopy and conventional digital image processing. It is also well suited for the biological assays and quantitative real-time analysis since it provides spectral and spatial data of samples. The method grants detailed information about a sample by recording the entire spectrum in each pixel of the whole image. We applied HSI to quantify the constituent pH variation in a single infected apoptotic monocyte as a model system. Previously, we showed that the human-pathogenic fungus Aspergillus fumigatus conidia interfere with the acidification of phagolysosomes. Here, we extended this finding to monocytes and gained a more detailed analysis of this process. Our data indicate that melanised A. fumigatus conidia have the ability to interfere with apoptosis in human monocytes as they enable the apoptotic cell to recover from mitochondrial acidification and to continue with the cell cycle. We also showed that this ability of A. fumigatus is dependent on the presence of melanin, since a non-pigmented mutant did not stop the progression of apoptosis and consequently, the cell did not recover from the acidic pH. By conducting the current research based on the HSI, we could measure the intracellular pH in an apoptotic infected human monocyte and show the pattern of pH variation during 35 h of measurements. As a conclusion, we showed the importance of melanin for determining the fate of intracellular pH in a single apoptotic cell.
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Heinrich V. Controlled One-on-One Encounters between Immune Cells and Microbes Reveal Mechanisms of Phagocytosis. Biophys J 2016; 109:469-76. [PMID: 26244729 DOI: 10.1016/j.bpj.2015.06.042] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 05/25/2015] [Accepted: 06/22/2015] [Indexed: 12/31/2022] Open
Abstract
Among many challenges facing the battle against infectious disease, one quandary stands out. On the one hand, it is often unclear how well animal models and cell lines mimic human immune behavior. On the other hand, many core methods of cell and molecular biology cannot be applied to human subjects. For example, the profound susceptibility of neutropenic patients to infection marks neutrophils (the most abundant white blood cells in humans) as vital immune defenders. Yet because these cells cannot be cultured or genetically manipulated, there are gaps in our understanding of the behavior of human neutrophils. Here, we discuss an alternative, interdisciplinary strategy to dissect fundamental mechanisms of immune-cell interactions with bacteria and fungi. We show how biophysical analyses of single-live-cell/single-target encounters are revealing universal principles of immune-cell phagocytosis, while also dispelling misconceptions about the minimum required mechanistic determinants of this process.
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Affiliation(s)
- Volkmar Heinrich
- Department of Biomedical Engineering, University of California Davis, Davis, California.
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14
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Roth KB, Neeves KB, Squier J, Marr DWM. High-throughput linear optical stretcher for mechanical characterization of blood cells. Cytometry A 2016; 89:391-7. [PMID: 26565892 PMCID: PMC10625799 DOI: 10.1002/cyto.a.22794] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 07/29/2015] [Accepted: 10/19/2015] [Indexed: 11/09/2022]
Abstract
This study describes a linear optical stretcher as a high-throughput mechanical property cytometer. Custom, inexpensive, and scalable optics image a linear diode bar source into a microfluidic channel, where cells are hydrodynamically focused into the optical stretcher. Upon entering the stretching region, antipodal optical forces generated by the refraction of tightly focused laser light at the cell membrane deform each cell in flow. Each cell relaxes as it flows out of the trap and is compared to the stretched state to determine deformation. The deformation response of untreated red blood cells and neutrophils were compared to chemically treated cells. Statistically significant differences were observed between normal, diamide-treated, and glutaraldehyde-treated red blood cells, as well as between normal and cytochalasin D-treated neutrophils. Based on the behavior of the pure, untreated populations of red cells and neutrophils, a mixed population of these cells was tested and the discrete populations were identified by deformability. © 2015 International Society for Advancement of Cytometry.
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Affiliation(s)
- Kevin B. Roth
- Chemical and Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401
| | - Keith B. Neeves
- Chemical and Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401
- Department of Pediatrics, University of Colorado, Denver, Colorado 80045
| | - Jeff Squier
- Department of Physics, Colorado School of Mines, Golden, Colorado 80401
| | - David W. M. Marr
- Chemical and Biological Engineering Department, Colorado School of Mines, Golden, Colorado 80401
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15
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Mierke CT. The fundamental role of mechanical properties in the progression of cancer disease and inflammation. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2014; 77:076602. [PMID: 25006689 DOI: 10.1088/0034-4885/77/7/076602] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The role of mechanical properties in cancer disease and inflammation is still underinvestigated and even ignored in many oncological and immunological reviews. In particular, eight classical hallmarks of cancer have been proposed, but they still ignore the mechanics behind the processes that facilitate cancer progression. To define the malignant transformation of neoplasms and finally reveal the functional pathway that enables cancer cells to promote cancer progression, these classical hallmarks of cancer require the inclusion of specific mechanical properties of cancer cells and their microenvironment such as the extracellular matrix as well as embedded cells such as fibroblasts, macrophages or endothelial cells. Thus, this review will present current cancer research from a biophysical point of view and will therefore focus on novel physical aspects and biophysical methods to investigate the aggressiveness of cancer cells and the process of inflammation. As cancer or immune cells are embedded in a certain microenvironment such as the extracellular matrix, the mechanical properties of this microenvironment cannot be neglected, and alterations of the microenvironment may have an impact on the mechanical properties of the cancer or immune cells. Here, it is highlighted how biophysical approaches, both experimental and theoretical, have an impact on the classical hallmarks of cancer and inflammation. It is even pointed out how these biophysical approaches contribute to the understanding of the regulation of cancer disease and inflammatory responses after tissue injury through physical microenvironmental property sensing mechanisms. The recognized physical signals are transduced into biochemical signaling events that guide cellular responses, such as malignant tumor progression, after the transition of cancer cells from an epithelial to a mesenchymal phenotype or an inflammatory response due to tissue injury. Moreover, cell adaptation to mechanical alterations, in particular the understanding of mechano-coupling and mechano-regulating functions in cell invasion, appears as an important step in cancer progression and inflammatory response to injuries. This may lead to novel insights into cancer disease and inflammatory diseases and will overcome classical views on cancer and inflammation. In addition, this review will discuss how the physics of cancer and inflammation can help to reveal whether cancer cells will invade connective tissue and metastasize or how leukocytes extravasate and migrate through the tissue. In this review, the physical concepts of cancer progression, including the tissue basement membrane a cancer cell is crossing, its invasion and transendothelial migration as well as the basic physical concepts of inflammatory processes and the cellular responses to the mechanical stress of the microenvironment such as external forces and matrix stiffness, are presented and discussed. In conclusion, this review will finally show how physical measurements can improve classical approaches that investigate cancer and inflammatory diseases, and how these physical insights can be integrated into classical tumor biological approaches.
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Affiliation(s)
- Claudia Tanja Mierke
- Faculty of Physics and Earth Science, Institute of Experimental Physics I, Biological Physics Division, University of Leipzig, Linnéstr. 5, 04103 Leipzig, Germany
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16
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Abstract
Differential adhesion provides a mechanical force to drive cells into stable configurations during the assembly of tissues and organs. This is well illustrated in the Drosophila eye where differential adhesion plays a role in sequential recruitment of all support cells. Cell adhesion, on the other hand, is linked to the cytoskeleton and subject to regulation by cell signaling. The integration of cell adhesion with the cytoskeleton and cell signaling may provide a more thorough explanation for the diversity of forms and shapes seen in tissues and organs.
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Affiliation(s)
- Sujin Bao
- Saint James School of Medicine , Bonaire , Caribbean Netherlands
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17
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Rowat AC, Jaalouk DE, Zwerger M, Ung WL, Eydelnant IA, Olins DE, Olins AL, Herrmann H, Weitz DA, Lammerding J. Nuclear envelope composition determines the ability of neutrophil-type cells to passage through micron-scale constrictions. J Biol Chem 2013; 288:8610-8618. [PMID: 23355469 PMCID: PMC3605679 DOI: 10.1074/jbc.m112.441535] [Citation(s) in RCA: 223] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 01/15/2013] [Indexed: 11/06/2022] Open
Abstract
Neutrophils are characterized by their distinct nuclear shape, which is thought to facilitate the transit of these cells through pore spaces less than one-fifth of their diameter. We used human promyelocytic leukemia (HL-60) cells as a model system to investigate the effect of nuclear shape in whole cell deformability. We probed neutrophil-differentiated HL-60 cells lacking expression of lamin B receptor, which fail to develop lobulated nuclei during granulopoiesis and present an in vitro model for Pelger-Huët anomaly; despite the circular morphology of their nuclei, the cells passed through micron-scale constrictions on similar timescales as scrambled controls. We then investigated the unique nuclear envelope composition of neutrophil-differentiated HL-60 cells, which may also impact their deformability; although lamin A is typically down-regulated during granulopoiesis, we genetically modified HL-60 cells to generate a subpopulation of cells with well defined levels of ectopic lamin A. The lamin A-overexpressing neutrophil-type cells showed similar functional characteristics as the mock controls, but they had an impaired ability to pass through micron-scale constrictions. Our results suggest that levels of lamin A have a marked effect on the ability of neutrophils to passage through micron-scale constrictions, whereas the unusual multilobed shape of the neutrophil nucleus is less essential.
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Affiliation(s)
- Amy C Rowat
- Department of Integrative Biology and Physiology, UCLA, Los Angeles, California 90095; Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, Massachusetts 02139; Department of Physics and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138.
| | - Diana E Jaalouk
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, Massachusetts 02139
| | - Monika Zwerger
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, Massachusetts 02139
| | - W Lloyd Ung
- Department of Physics and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
| | - Irwin A Eydelnant
- Department of Physics and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
| | - Don E Olins
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New England, Portland, Maine 04103
| | - Ada L Olins
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New England, Portland, Maine 04103
| | - Harald Herrmann
- Division of Molecular Genetics, German Cancer Research Center, D-69120 Heidelberg, Germany
| | - David A Weitz
- Department of Physics and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
| | - Jan Lammerding
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Cambridge, Massachusetts 02139; Weill Institute for Cell and Molecular Biology, Department of Biomedical Engineering, Cornell University, Ithaca, New York 14853
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18
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Kühni-Boghenbor K, Ma M, Lemgruber L, Cyrklaff M, Frischknecht F, Gaschen V, Stoffel M, Baumgartner M. Actin-mediated plasma membrane plasticity of the intracellular parasite Theileria annulata. Cell Microbiol 2012; 14:1867-79. [PMID: 22891986 DOI: 10.1111/cmi.12006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 06/22/2012] [Accepted: 08/07/2012] [Indexed: 11/27/2022]
Abstract
Pathogen-host interactions are modulated at multiple levels by both the pathogen and the host cell. Modulation of host cell functions is particularly intriguing in the case of the intracellular Theileria parasite, which resides as a multinucleated schizont free in the cytosol of the host cell. Direct contact between the schizont plasma membrane and the cytoplasm enables the parasite to affect the function of host cell proteins through direct interaction or through the secretion of regulators. Structure and dynamics of the schizont plasma membrane are poorly understood and whether schizont membrane dynamics contribute to parasite propagation is not known. Here we show that the intracellular Theileria schizont can dynamically change its shape by actively extending filamentous membrane protrusions. We found that isolated schizonts bound monomeric tubulin and in vitro polymerized microtubules, and monomeric tubulin polymerized into dense assemblies at the parasite surface. However, we established that isolated Theileria schizonts free of host cell microtubules maintained a lobular morphology and extended filamentous protrusions, demonstrating that host microtubules are dispensable both forthe maintenance of lobular schizont morphology and for the generation of membrane protrusions. These protrusions resemble nanotubes and extend in an actin polymerization-dependent manner; using cryo-electron tomography, we detected thin actin filaments beneath these protrusions, indicating that their extension is driven by schizont actin polymerization. Thus the membrane of the schizont and its underlying actin cytoskeleton possess intrinsic activity for shape control and likely function as a peri-organelle to interact with and manipulate host cell components.
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19
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Holden NJ, Savage COS, Young SP, Wakelam MJ, Harper L, Williams JM. A dual role for diacylglycerol kinase generated phosphatidic acid in autoantibody-induced neutrophil exocytosis. Mol Med 2011; 17:1242-52. [PMID: 21833457 DOI: 10.2119/molmed.2011.00028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 08/05/2011] [Indexed: 01/12/2023] Open
Abstract
Dysregulated release of neutrophil azurophilic granules causes increased tissue damage and amplified inflammation during autoimmune disease. Antineutrophil cytoplasmic antibodies (ANCAs) are implicated in the pathogenesis of small vessel vasculitis and promote adhesion and exocytosis in neutrophils. ANCAs activate specific signal transduction pathways in neutrophils that have the potential to be modulated therapeutically to prevent neutrophil activation by ANCAs. We have investigated a role for diacylglycerol kinase (DGK) and its downstream product phosphatidic acid (PA) in ANCA-induced neutrophil exocytosis. Neutrophils incubated with the DGK inhibitor R59022, before treatment with ANCAs, exhibited a reduced capacity to release their azurophilic granules, demonstrated by a component release assay and flow cytometry. PA restored azurophilic granule release in DGK-inhibited neutrophils. Confocal microscopy revealed that R59022 did not inhibit translocation of granules, indicating a role for DGK during the process of granule fusion at the plasma membrane. In investigating possible mechanisms by which PA promotes neutrophil exocytosis, we demonstrated that exocytosis can only be restored in R59022-treated cells through simultaneous modulation of membrane fusion and increasing cytosolic calcium. PA and its associated pathways may represent viable drug targets to reduce tissue injury associated with ANCA-associated vasculitic diseases and other neutrophilic inflammatory disorders.
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Affiliation(s)
- Neil J Holden
- Renal Immunobiology, School of Immunity and Infection, University of Birmingham, Birmingham, United Kingdom
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20
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Bose S, Das SK, Karp JM, Karnik R. A semianalytical model to study the effect of cortical tension on cell rolling. Biophys J 2011; 99:3870-9. [PMID: 21156128 DOI: 10.1016/j.bpj.2010.10.038] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 09/29/2010] [Accepted: 10/21/2010] [Indexed: 01/13/2023] Open
Abstract
Cell rolling on the vascular endothelium plays an important role in trafficking of leukocytes, stem cells, and cancer cells. We describe a semianalytical model of cell rolling that focuses on the microvillus as the unit of cell-substrate interaction and integrates microvillus mechanics, receptor clustering, force-dependent receptor-ligand kinetics, and cortical tension that enables incorporation of cell body deformation. Using parameters obtained from independent experiments, the model showed excellent agreement with experimental studies of neutrophil rolling on P-selectin and predicted different regimes of cell rolling, including spreading of the cells on the substrate under high shear. The cortical tension affected the cell-surface contact area and influenced the rolling velocity, and modulated the dependence of rolling velocity on microvillus stiffness. Moreover, at the same shear stress, microvilli of cells with higher cortical tension carried a greater load compared to those with lower cortical tension. We also used the model to obtain a scaling dependence of the contact radius and cell rolling velocity under different conditions of shear stress, cortical tension, and ligand density. This model advances theoretical understanding of cell rolling by incorporating cortical tension and microvillus extension into a versatile, semianalytical framework.
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Affiliation(s)
- Suman Bose
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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21
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Starodubtseva MN, Kavalenka AI, Yegorenkov NI, Petrenyov DR, Cherenkevich SN. Peroxynitrite regulates exocytosis of neutrophil granules. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2010. [DOI: 10.1134/s1990747810040021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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22
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Yu T, Wu X, Gupta KB, Kucik DF. Affinity, lateral mobility, and clustering contribute independently to beta 2-integrin-mediated adhesion. Am J Physiol Cell Physiol 2010; 299:C399-410. [PMID: 20445173 DOI: 10.1152/ajpcell.00039.2009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Affinity changes and avidity modulation both contribute to activation of beta(2)-integrin-mediated adhesion, an essential, early step in inflammation. Avidity modulation, defined as an increase in adhesiveness independent of integrin conformational changes, might be due to integrin clustering, motion, or both. Increased integrin diffusion upon leukocyte activation has been demonstrated, but whether it is proadhesive in itself, or just constitutes a mechanism for integrin clustering, remains unclear. To understand the proadhesive effects of integrin affinity changes, clustering, and motion, an experimental system was devised to separate them. Clustering and integrin motion together were induced by cytochalasin D (CD) without inducing high-affinity; integrin motion could then be frozen by fixation; and high affinity was induced independently by Mn(2+). Adhesion was equivalent for fixed and unfixed cells except following pretreatment with CD or Mn(2+), which increased adhesion for both. However, fixed cells were less adhesive than unfixed cells after CD, even though integrin clustering was similar. A simple explanation is that CD induces both clustering and integrin motion, fixation then stops motion on fixed cells, but integrins continue to diffuse on unfixed cells, increasing the kinetics of integrin/ICAM-1 interactions to enhance adhesion. Affinity changes are then independent of, and additive to, avidity effects.
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Affiliation(s)
- Tao Yu
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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23
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Abstract
Water is the dominant ingredient of cells and its dynamics are crucial to life. We and others have suggested a physical picture of the cell as a soft, fluid-infiltrated sponge, surrounded by a water-permeable barrier. To understand water movements in an animal cell, we imposed an external, inhomogeneous osmotic stress on cultured cancer cells. This forced water through the membrane on one side, and out on the other. Inside the cell, it created a gradient in hydration, that we visualized by tracking cellular responses using natural organelles and artificially introduced quantum dots. The dynamics of these markers at short times were the same for normal and metabolically poisoned cells, indicating that the cellular responses are primarily physical rather than chemical. Our finding of an internal gradient in hydration is inconsistent with a continuum model for cytoplasm, but consistent with the sponge model, and implies that the effective pore size of the sponge is small enough to retard water flow significantly on time scales ( approximately 10-100 seconds) relevant to cell physiology. We interpret these data in terms of a theoretical framework that combines mechanics and hydraulics in a multiphase poroelastic description of the cytoplasm and explains the experimentally observed dynamics quantitatively in terms of a few coarse-grained parameters that are based on microscopically measurable structural, hydraulic and mechanical properties. Our fluid-filled sponge model could provide a unified framework to understand a number of disparate observations in cell morphology and motility.
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Affiliation(s)
- Guillaume T Charras
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
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24
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Xu G, Shao JY. Human neutrophil surface protrusion under a point load: location independence and viscoelasticity. Am J Physiol Cell Physiol 2008; 295:C1434-44. [PMID: 18815230 DOI: 10.1152/ajpcell.00136.2008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mechanical properties of neutrophils have been recognized as key contributors to stabilizing neutrophil rolling on the endothelium during the inflammatory response. In particular, accumulating evidence suggests that surface protrusion and tether extraction from neutrophils facilitate stable rolling by relieving the disruptive forces on adhesive bonds. Using a customized optical trap setup, we applied piconewton-level pulling forces on targeted receptors that were located either on the microvillus tip (CD162) or intermicrovillus surface of neutrophils (CD18 and CD44). Under a constant force-loading rate, there always occurred an initial tent-like surface protrusion that was terminated either by rupture of the adhesion or by a "yield" or "crossover" to tether extraction. The corresponding protrusional stiffness of neutrophils was found to be between 0.06 and 0.11 pN/nm, depending on the force-loading rate and the cytoskeletal integrity, but not on the force location, the medium osmolality, nor the temperature increase from 22 degrees C to 37 degrees C. More importantly, we found that neutrophil surface protrusion was accompanied by force relaxation and hysteresis. In addition, the crossover force did not change much in the range of force-loading rates studied, and the protrusional stiffness of lymphocytes was similar to that of neutrophils. These results show that neutrophil surface protrusion is essentially viscoelastic, with a protrusional stiffness that stems primarily from the actin cortex, and the crossover force is independent of the receptor-cytoskeleton interaction.
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Affiliation(s)
- Gang Xu
- Dept. of Biomedical Engineering, Washington Univ. in St. Louis, Campus Box 1097, Rm 290E Whitaker Hall, One Brookings Dr., St. Louis, MO 63130-4899, USA
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25
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Abstract
Prolonged exposure to fluid shear stress alters leukocyte functions associated with the immune response. We examined the initial response of freshly isolated human leukocytes to fluid shear stress under high magnification. Adherent leukocytes exhibit a rapid biomechanical response to physiological levels of fluid shear stress. After passive displacement in the direction of a constant fluid shear stress, adherent leukocytes actively recoil back in the opposite direction of the fluid flow. Recoil is observed within seconds of the applied fluid shear stress. Simultaneously, fluid shear stress induces a stiffening of the cell. The immediate cell displacement in response to a step increase in fluid shear stress is greatly attenuated in subsequent steps compared to the initial fluid shear stress step. Recoil is not mediated by actin polymerization-dependent mechanisms, as cytochalasin D had no effect on this early response. However, stiffening was determined in part by an intact actin cytoskeleton. Inhibiting myosin force generation with ML-7 abolished the recoil and stiffening responses, implicating force generation by myosin as an important contributor to the early leukocyte response to fluid shear stress. This initial shear stress response may be particularly important in facilitating leukocyte attachment under sustained fluid shear stress by the flowing blood in the microcirculation.
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26
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Simon SI, Nyunt T, Florine-Casteel K, Ritchie K, Ting-Beall HP, Evans E, Needham D. Dynamics of neutrophil membrane compliance and microstructure probed with a micropipet-based piconewton force transducer. Ann Biomed Eng 2007; 35:595-604. [PMID: 17370125 DOI: 10.1007/s10439-007-9260-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Accepted: 01/12/2007] [Indexed: 11/24/2022]
Abstract
A novel biointerface probe was implemented to study the deformability of the neutrophil membrane and cortical cytoskeleton. Piconewton scale forces are applied to the cell using an ultrasensitive and tunable force transducer comprised of an avidin-coated microsphere attached to a biotinylated and swollen red blood cell. Deformations of freshly isolated human neutrophils were observed on the stage of an inverted phase contrast microscope. Force versus probe indentation curves over a cycle of contact, indentation, and retraction revealed three distinct material responses. Small probe deformations (approximately 500 nm) tested over a range of rates (e.g. 100-500 nm/s) revealed predominantly an elastic response. An initial low-slope region in the force-indentation curves (approximately 0.005 pN/nm), typically extending 0.5-1.0 microm from the cell surface was interpreted as probe contact with microvilli extensions. Further deformation yielded a slope of 0.054+/-0.006 pN/nm, indicative of a stiffer cortical membrane. Disrupting cytoskeletal actin organization by pretreatment with cytochalasin D, reduced the slope by 40% to 0.033+/-0.007 pN/nm and introduced hysteresis in the recovery phase. Modeling the neutrophil as a liquid drop with constant surface tension yielded values of cortical tension of 0.035 pN/nm for resting and 0.02 pN/nm for cytochalasin-treated neutrophils. These data demonstrate the utility of the biointerface probe for measuring local surface compliance and microstructure of living cells.
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Affiliation(s)
- Scott I Simon
- Biomedical Engineering, University of California-Davis, 1 Shields Ave., Davis, CA 95616-5294, USA.
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27
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Nazareth H, Genagon SA, Russo TA. Extraintestinal pathogenic Escherichia coli survives within neutrophils. Infect Immun 2007; 75:2776-85. [PMID: 17296761 PMCID: PMC1932911 DOI: 10.1128/iai.01095-06] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Extracellular pathogenic Escherichia coli (ExPEC) strains are common causes of a variety of clinical syndromes, including urinary tract infections, abdominal infections, nosocomial pneumonia, neonatal meningitis, and sepsis. ExPEC strains are extracellular bacterial pathogens; therefore, the innate immune response (e.g., professional phagocytes) plays a crucial role in the host defense against them. Studies using the model ExPEC strain CP9 demonstrated that it is relatively resistant to neutrophil-mediated bactericidal activity. Although this could be due to resistance to phagocytosis, the ability of CP9 to survive the intracellular killing mechanisms of neutrophils is another possibility. Using a variation of the intracellular invasion assay, we studied the survival of CP9 within peripheral blood-derived human neutrophils. Our results indicated that CP9 did survive within human neutrophils, but we were unable to demonstrate that intracellular replication occurred. This finding was not unique to CP9, since when a conservative assessment of survival was used, four of six additional ExPEC strains, but not an E. coli laboratory strain, were also capable of survival within neutrophils. Initial studies in which we began to decipher the mechanisms by which CP9 is able to successfully survive intracellular neutrophil-mediated bactericidal activity demonstrated that CP9 was at least partially susceptible to the neutrophil oxidative burst. Therefore, absolute resistance to the oxidative burst is not a mechanism by which ExPEC survives within neutrophils. In addition, electron microscopy studies showed that CP9 appeared to be present in phagosomes within neutrophils. Therefore, avoidance of phagosomal uptake or subsequent escape from the phagosome does not appear to be a mechanism that contributes to CP9's survival. These findings suggest that survival of ExPEC within neutrophils may be an important virulence mechanism.
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Affiliation(s)
- Helen Nazareth
- Department of Medicine, Division of Infectious Diseases, 3435 Main Street, Biomedical Research Building, Room 141, Buffalo, NY 14214, USA
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28
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Fexby S, Bjarnsholt T, Jensen PØ, Roos V, Høiby N, Givskov M, Klemm P. Biological Trojan horse: Antigen 43 provides specific bacterial uptake and survival in human neutrophils. Infect Immun 2007; 75:30-4. [PMID: 17030570 PMCID: PMC1828374 DOI: 10.1128/iai.01117-06] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Escherichia coli is a versatile pathogen causing millions of infections in humans every year. This bacterium can form multicellular aggregates when it expresses a self-associating protein, antigen 43 (Ag43), on its surface. We have discovered that Ag43-expressing E. coli cells are efficiently taken up by human defense cells, polymorphonuclear neutrophils (PMNs), in an opsonin-independent manner. Surprisingly, the phagocytosed bacteria were not immediately killed but resided as tight aggregates within the PMNs. Our observations indicate that Ag43-mediated uptake and survival in PMNs constitute a mechanism to subvert one of the primary defense mechanisms of the human body.
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Affiliation(s)
- Sara Fexby
- Center for Biomedical Microbiology, BioCentrum-DTU, Building 301, Technical University of Denmark, DK-2800 Lyngby, Denmark
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29
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Edmondson KE, Denney WS, Diamond SL. Neutrophil-bead collision assay: pharmacologically induced changes in membrane mechanics regulate the PSGL-1/P-selectin adhesion lifetime. Biophys J 2005; 89:3603-14. [PMID: 16100264 PMCID: PMC1366853 DOI: 10.1529/biophysj.105.066134] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Visualization of flowing neutrophils colliding with adherent 1-mum-diameter beads presenting P-selectin allowed the simultaneous measurement of collision efficiency (epsilon), membrane tethering fraction (f), membrane tether growth dynamics, and PSGL-1/P-selectin binding lifetime. For 1391 collisions analyzed over venous wall shear rates from 25 to 200 s(-1), epsilon decreased from 0.17 to 0.004, whereas f increased from 0.15 to 0.70, and the average projected membrane tether length, L(tether)(m), increased from 0.35 mum to approximately 2.0 mum over this shear range. At all shear rates tested, adhesive collisions lacking membrane tethers had average bond lifetimes less than those observed for collisions with tethers. For adhesive collisions that failed to form membrane tethers, the regressed Bell parameters (consistent with single bond Monte Carlo simulation) were zero-stress off-rate, k(off)(0) = 0.56 s(-1) and reactive compliance, r = 0.10 nm, similar to published atomic force microscopy (AFM) measurements. For all adhesion events (+/- tethers), the bond lifetime distributions were more similar to those obtained by rolling assay and best simulated by Monte Carlo with the above Bell parameters and an average of 1.48 bonds (n = 1 bond (67%), n = 2 (22%), and n = 3-5 (11%)). For collisions at 100 s(-1), pretreatment of neutrophils with actin depolymerizing agents, latrunculin or cytochalasin D, had no effect on epsilon, but increased L(tether)(m) by 1.74- or 2.65-fold and prolonged the average tether lifetime by 1.41- or 1.65-fold, respectively. Jasplakinolide, an actin polymerizing agent known to cause blebbing, yielded results similar to the depolymerizing agents. Conversely, cholesterol-depletion with methyl-beta-cyclodextrin or formaldehyde fixation had no effect on epsilon, but reduced L(tether)(m) by 66% or 97% and reduced the average tether lifetime by 30% or 42%, respectively. The neutrophil-bead collision assay combines advantages of atomic force microscopy (small contact zone), aggregometry (discrete interactions), micropipette manipulation (tether visualization), and rolling assays (physiologic flow loading). Membrane tether growth can be enhanced or reduced pharmacologically with consequent effects on PSGL-1/P-selectin lifetimes.
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Affiliation(s)
- K E Edmondson
- Institute for Medicine and Engineering, Department of Bioengineering, University of Pennsylvania, 3320 Smith Walk, Philadelphia, PA 19104, USA
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30
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Wong PK, Tan W, Ho CM. Cell relaxation after electrodeformation: effect of latrunculin A on cytoskeletal actin. J Biomech 2005; 38:529-35. [PMID: 15652551 DOI: 10.1016/j.jbiomech.2004.04.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2004] [Indexed: 10/26/2022]
Abstract
Precise measurement of the mechanical properties of a cell provides useful information about its structural organization and physiological state. It is interesting to understand the effect of individual components on the mechanical properties of the entire cell. In this study, we investigate the influence of the cytoskeletal actin on the viscoelastic properties of a cell. Actin-specific agents, including latrunculin A and jasplakinolide, are used to alter the organization of the cytoskeletal actin. Brassica oleracea protoplasts are treated with the drugs and deformed under an external electric potential. The relaxation processes of single protoplasts after electrodeformation are measured. The data are analyzed by a model-independent spectrum recovery algorithm. Two distinct characteristic time constants are obtained from the relaxation spectra. Treatment with latrunculin A increases both of the relaxation time constants. The longest relaxation times for control, latrunculin A treated, and jasplakinolide treated cells are determined to be 0.28, 1.0, and 0.21 s, respectively.
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Affiliation(s)
- Pak Kin Wong
- Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA 90095, USA
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31
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Coughlin MF, Schmid-Schönbein GW. Pseudopod projection and cell spreading of passive leukocytes in response to fluid shear stress. Biophys J 2005; 87:2035-42. [PMID: 15345579 PMCID: PMC1304606 DOI: 10.1529/biophysj.104.042192] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recent evidence suggests that circulating leukocytes respond to physiological levels of fluid shear stress. This study was designed to examine the shear stress response of individual leukocytes adhering passively to a glass surface. Human leukocytes were exposed to a step fluid shear stress with amplitude between 0.2 and 4 dyn/cm(2) and duration between 1 and 20 min. The response of the cells was determined in the form of projected cell area measurements by high-resolution observation before, during, and after fluid shear application. All cells selected initially had a round morphology. After application of fluid shear many cells projected pseudopodia and spread on the glass surface. The number of leukocytes responding with pseudopod projection and the extent of cell spreading increased with increasing amplitude and duration of fluid shear stress. Pseudopod projection after exposure to a step fluid shear occurs following a delay that is insensitive to the shear stress amplitude and duration. Leukocytes that did not project pseudopodia and spread in response to low shear stress could be shown to respond to a second shear step of higher amplitude. The spreading response requires an intact actin network and activated myosin molecules. Depleting the cell glycocalyx with protease treatment enhances the spreading response in sheared leukocytes. These results indicate that passive leukocytes respond to fluid shear stress with active pseudopod projection and cell spreading. This behavior may contribute to cell spreading on endothelium and other cells as well as to transendothelial migration of leukocytes in the microcirculation.
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Affiliation(s)
- Mark F Coughlin
- Department of Bioengineering, The Whitaker Institute for Biomedical Engineering, University of California, San Diego, La Jolla, California 92093-0412, USA.
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32
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Ni N, Kevil CG, Bullard DC, Kucik DF. Avidity modulation activates adhesion under flow and requires cooperativity among adhesion receptors. Biophys J 2004; 85:4122-33. [PMID: 14645099 PMCID: PMC1303711 DOI: 10.1016/s0006-3495(03)74824-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
An early step in activation of leukocyte adhesion is a release of integrins from cytoskeletal constraints on their diffusion, leading to rearrangement and, consequently, increased avidity. Static adhesion assays using purified ligand as a substrate have demonstrated that very low doses of cytochalasin D disconnect beta2-integrins from their cytoskeletal links, allowing rearrangement and activating adhesion. The adhesion process in blood vessels is poorly simulated by these assays, however, for two reasons: leukocyte adhesion to endothelium 1), occurs in the presence of blood flow and 2), involves the simultaneous interactions of multiple sets of adhesion molecules. We investigated the effect of cytochalasin D, at concentrations that increase integrin diffusion but do not alter leukocyte shape and surface features, on adhesion of leukocytes to endothelial cells under flow. Cytochalasin D increased the number of rolling cells, the number of firmly adherent cells, and the duration of both rolling and firm adhesion. These effects required endothelial cell expression of ICAM-1, the ligand for leukocyte beta2-integrins. The beta2-integrin-ICAM-1 interaction alone was not sufficient, however. Experiments using purified substrates demonstrated that avidity effects on activation of adhesion under flow require functional cooperativity between integrins and other adhesion receptors.
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Affiliation(s)
- Na Ni
- Department of Genomics and Pathobiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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33
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Witteck A, Yao Y, Fechir M, Förstermann U, Kleinert H. Rho protein-mediated changes in the structure of the actin cytoskeleton regulate human inducible NO synthase gene expression. Exp Cell Res 2003; 287:106-15. [PMID: 12799187 DOI: 10.1016/s0014-4827(03)00129-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Rho proteins (Rho, Rac, Cdc 42) are known to control the organization of the actin cytoskeleton as well as gene expression. Inhibition of Rho proteins by Clostridium difficile toxin B disrupted the F-actin cytoskeleton and enhanced cytokine-induced inducible nitric oxide synthase (iNOS) expression in human epithelial cells. Also specific inhibition by Y-27632 of p160ROCK, which mediates Rho effects on actin fibers, caused a disruption of the actin cytoskeleton and a superinduction of cytokine-induced iNOS expression. Accordingly, direct disruption of the actin cytoskeleton by cytochalasin D, latrunculin B, or jasplakinolide enhanced cytokine-induced iNOS expression. The transcription factor serum response factor (SRF) has been described as mediating actin cytoskeleton-dependent regulation of gene expression. Direct targets of SRF are activating protein 1 (AP1)-dependent genes. All compounds used inhibited SRF- and AP1-dependent reporter gene expression in DLD-1 cells. However, the enhancing effect of the actin cytoskeleton-disrupting compounds on human iNOS promoter activity was much less pronounced than the effect on iNOS mRNA expression. Therefore, besides transcriptional mechanisms, posttranscriptional effects seem to be involved in the regulation of iNOS expression by the above compounds. In conclusion, our data suggest that Rho protein-mediated changes of the actin cytoskeleton negatively modulate the expression of human iNOS.
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MESH Headings
- Actin Cytoskeleton/drug effects
- Actin Cytoskeleton/metabolism
- Bacterial Proteins
- Bacterial Toxins/pharmacology
- Bridged Bicyclo Compounds, Heterocyclic/pharmacology
- Cytochalasin D/pharmacology
- Cytokines/metabolism
- Cytokines/pharmacology
- Cytoskeleton/drug effects
- Cytoskeleton/metabolism
- Depsipeptides
- Enzyme Inhibitors/pharmacology
- Eukaryotic Cells/enzymology
- Gene Expression Regulation, Enzymologic/drug effects
- Gene Expression Regulation, Enzymologic/genetics
- Humans
- Intracellular Signaling Peptides and Proteins
- Nitric Oxide/metabolism
- Nitric Oxide Synthase/drug effects
- Nitric Oxide Synthase/genetics
- Nitric Oxide Synthase/metabolism
- Peptides, Cyclic/pharmacology
- Promoter Regions, Genetic/drug effects
- Promoter Regions, Genetic/genetics
- Protein Serine-Threonine Kinases/antagonists & inhibitors
- Protein Serine-Threonine Kinases/metabolism
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Serum Response Factor/drug effects
- Serum Response Factor/genetics
- Serum Response Factor/metabolism
- Thiazoles/pharmacology
- Thiazolidines
- Transcription Factor AP-1/drug effects
- Transcription Factor AP-1/genetics
- Transcription Factor AP-1/metabolism
- Transcription, Genetic/drug effects
- Transcription, Genetic/genetics
- Tumor Cells, Cultured
- rho GTP-Binding Proteins/drug effects
- rho GTP-Binding Proteins/metabolism
- rho-Associated Kinases
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Affiliation(s)
- Andrea Witteck
- Department of Pharmacology, Johannes Gutenberg University, Obere Zahlbacher Strasse 67, D-55101, Mainz, Germany
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Pritchard S, Erickson GR, Guilak F. Hyperosmotically induced volume change and calcium signaling in intervertebral disk cells: the role of the actin cytoskeleton. Biophys J 2002; 83:2502-10. [PMID: 12414684 PMCID: PMC1302336 DOI: 10.1016/s0006-3495(02)75261-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Loading of the spine alters the osmotic environment in the intervertebral disk (IVD) as interstitial water is expressed from the tissue. Cells from the three zones of the IVD, the anulus fibrosus (AF), transition zone (TZ), and nucleus pulposus (NP), respond to osmotic stress with altered biosynthesis through a pathway that may involve calcium (Ca(2+)) as a second messenger. We examined the hypothesis that IVD cells respond to hyperosmotic stress by increasing the concentration of intracellular calcium ([Ca(2+)](i)) through a mechanism involving F-actin. In response to hyperosmotic stress, control cells from all zones decreased in volume and cells from the AF and TZ exhibited [Ca(2+)](i) transients, while cells from the NP did not. Extracellular Ca(2+) was necessary to initiate [Ca(2+)](i) transients. Stabilization of F-actin with phalloidin prevented the Ca(2+) response in AF and TZ cells and decreased the rate of volume change in cells from all zones, coupled with an increase in the elastic moduli and apparent viscosity. Conversely, actin breakdown with cytochalasin D facilitated Ca(2+) signaling while decreasing the elastic moduli and apparent viscosity for NP cells. These results suggest that hyperosmotic stress induces volume change in IVD cells and may initiate [Ca(2+)](i) transients through an actin-dependent mechanism.
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Affiliation(s)
- Scott Pritchard
- Department of Surgery, Duke University Medical Center, 374 Medical Sciences Research Building, Durham, NC 27710, USA
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35
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Bathe M, Shirai A, Doerschuk CM, Kamm RD. Neutrophil transit times through pulmonary capillaries: the effects of capillary geometry and fMLP-stimulation. Biophys J 2002; 83:1917-33. [PMID: 12324412 PMCID: PMC1302283 DOI: 10.1016/s0006-3495(02)73955-6] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The deformations of neutrophils as they pass through the pulmonary microcirculation affect their transit time, their tendency to contact and interact with the endothelial surface, and potentially their degree of activation. Here we model the cell as a viscoelastic Maxwell material bounded by constant surface tension and simulate indentation experiments to quantify the effects of (N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP)-stimulation on its mechanical properties (elastic shear modulus and viscosity). We then simulate neutrophil transit through individual pulmonary capillary segments to determine the relative effects of capillary geometry and fMLP-stimulation on transit time. Indentation results indicate that neutrophil viscosity and shear modulus increase by factors of 3.4, for 10(-9) M fMLP, and 7.3, for 10(-6) M fMLP, over nonstimulated cell values, determined to be 30.8 Pa.s and 185 Pa, respectively. Capillary flow results indicate that capillary entrance radius of curvature has a significant effect on cell transit time, in addition to minimum capillary radius and neutrophil stimulation level. The relative effects of capillary geometry and fMLP on neutrophil transit time are presented as a simple dimensionless expression and their physiological significance is discussed.
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Affiliation(s)
- Mark Bathe
- Department of Mechanical Engineering and Division of Biological Engineering, Massachusetts Institute of Technology, Cambridge 02139, USA
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36
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White P, Gu L, Chen J. Decreased actin solubility observed during ATP-depletion is mimicked by severing agents but not depolymerizing agents in isolated and cultured proximal tubular cells. Clin Physiol Funct Imaging 2002; 22:312-9. [PMID: 12487003 DOI: 10.1046/j.1475-097x.2002.00437.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The microvilli of the apical membrane of proximal tubule (PT) cells are supported by the underlying actin cytoskeleton. Ischaemic or anoxic ATP-depletion leads to the disruption of the actin cytoskeleton, resulting in microvillar retraction and loss of membrane polarity. Using isolated PT cells, we have previously demonstrated that actin filaments (F-actin) are likely severed during ATP-depletion. A sequential extraction protocol revealed a decrease in actin solubility, resulting in the sequestration of a distinct F-actin pool with the insoluble cellular complex in ATP-depleted PT cells. We demonstrate here that decreased actin solubility is not only a reliable end-marker of ATP-depletion induced injury in freshly isolated PT cells, but also serves as a biochemical marker in the cultured proximal tubular cell line LLC-PK1. In the present studies, we also investigated specific actin-binding drugs to determine if they mimic the effects observed during energy depletion. Jasplakinolide (JP), a compound which binds F-actin and prevents depolymerization, did not effect actin solubility during ATP-depletion. Furthermore, swinholide A (SA), an F-actin severing agent, resulted in decreased actin solubility, mimicking the effects of ATP-depletion. Interestingly, latrunculin A (LA), an agent which depolymerizes F-actin, did not reduce actin solubility, but rather resulted in an increase in digitonin-soluble actin. Taken collectively, our results support previous work and suggest that disruption of the actin cytoskeleton during ATP-depletion is mediated by F-actin severing/fragmentation and not depolymerization. The differential effects of F-actin disrupting agents and the consistencies observed in both models of ischaemic injury will provide a basis for a more detailed understanding of the pathological events of PT-cell dysfunction.
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Affiliation(s)
- Peter White
- Department of Natural Sciences, Colby-Sawyer College, New London, NH, USA
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37
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Shao JY, Xu J. A modified micropipette aspiration technique and its application to tether formation from human neutrophils. J Biomech Eng 2002; 124:388-96. [PMID: 12188205 DOI: 10.1115/1.1486469] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Tether formation, which is mechanically characterized by its threshold force and effective viscosity, is involved in neutrophil emigration from blood circulation. Using the micropipette aspiration technique, which was improved by quantitative contact control and computerized data analysis, we extracted tethers from human neutrophils treated with IL-8, PMA, or cytochalasin D. We found that both IL-8 and PMA elevated the threshold force to about twice as large as the value for passive neutrophils. All these treatments decreased the effective viscosity dramatically (approximately 80%). With a novel method, the residual cortical tension of the cytochalasin-D-treated non-spherical neutrophils was measured to be approximately 8.8 pN/microm.
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Affiliation(s)
- Jin-Yu Shao
- Department of Biomedical Engineering, Washington University, Saint Louis, MO 63130, USA.
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38
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Zhu C, Bao G, Wang N. Cell mechanics: mechanical response, cell adhesion, and molecular deformation. Annu Rev Biomed Eng 2002; 2:189-226. [PMID: 11701511 DOI: 10.1146/annurev.bioeng.2.1.189] [Citation(s) in RCA: 215] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
As the basic unit of life, the cell is a biologically complex system, the understanding of which requires a combination of various approaches including biomechanics. With recent progress in cell and molecular biology, the field of cell mechanics has grown rapidly over the last few years. This review synthesizes some of these recent developments to foster new concepts and approaches, and it emphasizes molecular-level understanding. The focuses are on the common themes and interconnections in three related areas: (a) the responses of cells to mechanical forces, (b) the mechanics and kinetics of cell adhesion, and (c) the deformation of biomolecules. Specific examples are also given to illustrate the quantitative modeling used in analyzing biological processes and physiological functions.
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Affiliation(s)
- C Zhu
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0363, USA.
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39
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MIYAZAKI H, HASEGAWA Y, HAYASHI K. Tensile Properties of Contractile and Synthetic Vascular Smooth Muscle Cells. ACTA ACUST UNITED AC 2002. [DOI: 10.1299/jsmec.45.870] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Hiroshi MIYAZAKI
- Division of Mechanical Science, Department of Systems and Human Science, Graduate School of Engineering Science, Osaka University
| | | | - Kozaburo HAYASHI
- Division of Mechanical Science, Department of Systems and Human Science, Graduate School of Engineering Science, Osaka University
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40
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Au BT, Teixeira MM, Collins PD, Williams TJ. Blockade of PAF receptors controls interleukin-8 production by regulating the activation of neutrophil CD11/CD18. Eur J Pharmacol 2001; 425:65-71. [PMID: 11672576 DOI: 10.1016/s0014-2999(01)01141-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The production of interleukin-8 by neutrophils in response to particulate stimuli may play a role in the recruitment and activation of further neutrophils in an inflammatory reaction. Here, we have evaluated the sequence of early events leading to interleukin-8 production by phagocytosing neutrophils. Kinetic experiments showed that the phagocytosis of zymosan particles by human neutrophils was rapid in onset. In contrast, interleukin-8 production was more protracted and only detectable 6 h later. Nevertheless, inhibition of phagocytosis with cytochalasins B or D suppressed the late interleukin-8 production. Activation of neutrophils with zymosan failed to enhance CD11/CD18 expression on the neutrophil surface but led to an increase in the expression of an activation-dependent epitope on CD11/CD18. Pretreatment with the platelet-activating factor (PAF) receptor antagonist, UK-74505 (4-(2-chlorophenyl)-1,4-dihydro-3-ethoxycarbonyl-6-methyl-2-[4-(2-methylimidazol[4,5-c]pyrid-1-yl)phenyl]-5-[N-(2-pyridyl)carbamoyl]pyridine), significantly blocked the increase in the expression of the activation epitope, resulting in inhibition of the phagocytosis of zymosan and interleukin-8 production. In conclusion, the activation of neutrophils with zymosan leads to the activation of PAF receptors and this is followed by activation of CD11/CD18, phagocytosis of zymosan particles and subsequent interleukin-8 release.
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Affiliation(s)
- B T Au
- Leukocyte Biology, Biomedical Science Division, Imperial College of Science, Technology and Medicine, Exhibition Road, London SW7 2AZ, UK
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41
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Guilak F, Ting-Beall HP, Baer AE, Trickey WR, Erickson GR, Setton LA. Viscoelastic properties of intervertebral disc cells. Identification of two biomechanically distinct cell populations. Spine (Phila Pa 1976) 1999; 24:2475-83. [PMID: 10626310 DOI: 10.1097/00007632-199912010-00009] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN A combined experimental and theoretical biomechanical study to quantify the mechanical properties of living cells of the porcine intervertebral disc. OBJECTIVES To quantify zonal variations in the mechanical properties and morphology of cells isolated from the intervertebral disc. SUMMARY OF BACKGROUND DATA Cellular response to mechanical stimuli is influenced by the mechanical properties of cells and of the extracellular matrix. Significant zonal variations in intervertebral disc matrix properties have been reported. No information is currently available on the corresponding regional variations in the mechanical properties of intervertebral disc cells, despite evidence of significant differences in cellular phenotype and biologic response to loading. METHODS The micropipette aspiration test was used in combination with a three-parameter viscoelastic solid model to measure the mechanical properties of cells isolated from the anulus fibrosus, transition zone, and nucleus pulposus. RESULTS Intervertebral disc cells exhibited viscoelastic solid behaviors. Highly significant differences were observed in the morphology, cytoskeletal arrangement, and biomechanical properties of the nucleus pulposus cells as compared with anulus fibrosus or transition zone cells. Cells of the nucleus pulposus were approximately three times stiffer and significantly more viscous than cells of the anulus fibrosus or transition zone. CONCLUSIONS The findings of this study provide new evidence for the existence of two biomechanically distinct cell populations in the intervertebral disc. These differences in mechanical behavior may be related to observed differences in the cytoskeletal architecture between these cells, and may further play an important role in the development, maintenance, and degeneration of the intervertebral disc.
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Affiliation(s)
- F Guilak
- Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA
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42
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Dai J, Ting-Beall HP, Hochmuth RM, Sheetz MP, Titus MA. Myosin I contributes to the generation of resting cortical tension. Biophys J 1999; 77:1168-76. [PMID: 10423462 PMCID: PMC1300408 DOI: 10.1016/s0006-3495(99)76968-7] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The amoeboid myosin I's are required for cellular cortical functions such as pseudopod formation and macropinocytosis, as demonstrated by the finding that Dictyostelium cells overexpressing or lacking one or more of these actin-based motors are defective in these processes. Defects in these processes are concomitant with changes in the actin-filled cortex of various Dictyostelium myosin I mutants. Given that the amoeboid myosin I's possess both actin- and membrane-binding domains, the mutant phenotypes could be due to alterations in the generation and/or regulation of cell cortical tension. This has been directly tested by analyzing mutant Dictyostelium that either lacks or overexpresses various myosin I's, using micropipette aspiration techniques. Dictyostelium cells lacking only one myosin I have normal levels of cortical tension. However, myosin I double mutants have significantly reduced (50%) cortical tension, and those that mildly overexpress an amoeboid myosin I exhibit increased cortical tension. Treatment of either type of mutant with the lectin concanavalin A (ConA) that cross-links surface receptors results in significant increases in cortical tension, suggesting that the contractile activity of these myosin I's is not controlled by this stimulus. These results demonstrate that myosin I's work cooperatively to contribute substantially to the generation of resting cortical tension that is required for efficient cell migration and macropinocytosis.
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Affiliation(s)
- J Dai
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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43
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Abstract
The short actin filaments in the erythrocyte's membrane skeleton are shown to be largely oriented tangent to the lipid bilayer. Actin "proto"-filaments have previously been described as junctional centers intertriangulated by spectrin; however, the protofilaments may simultaneously serve as pinning centers between the network and the overlying bilayer. The latter function now seems of particular importance because near-normal network assembly has been reported with transgenic mouse sphero-erythrocytes that lack the primary linkage protein Band 3. To assess possible physical constraints on actin protofilaments in intact membranes, fluorescence polarization microscopy (FPM) has been used to study rhodamine phalloidin-labeled red cell ghosts. A basis for interpreting FPM images of cells is provided by FPM applied to isolated actin filaments. These are labeled with the same rhodamine probes and imaged at various orientations with respect to the polarizers, including filament orientations perpendicular to the image plane. High aperture and fluorophore conjugation effects are found to be minimal, enabling development of a simple, semi-empirical model which indicates that protofilaments are generally within approximately 20 degrees of the membrane tangent plane.
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Affiliation(s)
- C Picart
- Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6315, USA
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44
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Alteration of Actin Organization by Jaspamide Inhibits Ruffling, but not Phagocytosis or Oxidative Burst, in HL-60 Cells and Human Monocytes. Blood 1999. [DOI: 10.1182/blood.v93.11.3994] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractJaspamide, a naturally occurring cyclic peptide isolated from the marine sponge Hemiastrella minor, has fungicidal and growth-inhibiting activities. Exposure of promyelocytic HL-60 cells and human monocytes to jaspamide induces a dramatic reorganization of actin from a typical fibrous network to focal aggregates. HL-60 cells exposed to 5 × 10−8 mol/L or 10−7 mol/L jaspamide exhibited a reduced proliferation rate. In addition, 10−7mol/L jaspamide induced maturation of HL-60 cells as indicated by the appearance of a lobulated nucleus in 55% ± 5% of the cells and immunophenotypic maturation of the leukemia cells (upregulation of CD16 and CD14 B antigens). Further characterization has shown that F-actin is aggregated both in HL-60 cells and in human monocytes exposed to 10−7 mol/L jaspamide. Well-spread cultured human monocytes contracted and adopted round shapes after treatment with jaspamide. Moreover, a dose-dependent increase in both total actin and de novo synthesized portions of the soluble actin was observed in jaspamide-treated HL-60 cells. Jaspamide treatment inhibits ruffling and intracellular movement in HL-60 cells and monocytes, but does not affect phagocytic activity or respiratory burst activity. The consequential effects of jaspamide-induced actin reorganization on ruffling, versus its negligible effect on phagocytosis and oxidative burst, may shed light on molecular mechanisms of actin involvement in these processes. Jaspamide disrupts the actin cytoskeleton of normal and malignant mammalian cells with no significant effect on phagocytic activity and may, therefore, be considered as a novel therapeutic agent.
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45
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Alteration of Actin Organization by Jaspamide Inhibits Ruffling, but not Phagocytosis or Oxidative Burst, in HL-60 Cells and Human Monocytes. Blood 1999. [DOI: 10.1182/blood.v93.11.3994.411k39_3994_4005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Jaspamide, a naturally occurring cyclic peptide isolated from the marine sponge Hemiastrella minor, has fungicidal and growth-inhibiting activities. Exposure of promyelocytic HL-60 cells and human monocytes to jaspamide induces a dramatic reorganization of actin from a typical fibrous network to focal aggregates. HL-60 cells exposed to 5 × 10−8 mol/L or 10−7 mol/L jaspamide exhibited a reduced proliferation rate. In addition, 10−7mol/L jaspamide induced maturation of HL-60 cells as indicated by the appearance of a lobulated nucleus in 55% ± 5% of the cells and immunophenotypic maturation of the leukemia cells (upregulation of CD16 and CD14 B antigens). Further characterization has shown that F-actin is aggregated both in HL-60 cells and in human monocytes exposed to 10−7 mol/L jaspamide. Well-spread cultured human monocytes contracted and adopted round shapes after treatment with jaspamide. Moreover, a dose-dependent increase in both total actin and de novo synthesized portions of the soluble actin was observed in jaspamide-treated HL-60 cells. Jaspamide treatment inhibits ruffling and intracellular movement in HL-60 cells and monocytes, but does not affect phagocytic activity or respiratory burst activity. The consequential effects of jaspamide-induced actin reorganization on ruffling, versus its negligible effect on phagocytosis and oxidative burst, may shed light on molecular mechanisms of actin involvement in these processes. Jaspamide disrupts the actin cytoskeleton of normal and malignant mammalian cells with no significant effect on phagocytic activity and may, therefore, be considered as a novel therapeutic agent.
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46
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Davidson LA, Oster GF, Keller RE, Koehl MA. Measurements of mechanical properties of the blastula wall reveal which hypothesized mechanisms of primary invagination are physically plausible in the sea urchin Strongylocentrotus purpuratus. Dev Biol 1999; 209:221-38. [PMID: 10328917 DOI: 10.1006/dbio.1999.9249] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Computer simulations showed that the elastic modulus of the cell layer relative to the elastic modulus of the extracellular layers predicted the effectiveness of different force-generating mechanisms for sea urchin primary invagination [L. A. Davidson, M. A. R. Koehl, R. Keller, and G. F. Oster (1995) Development 121, 2005-2018]. Here, we measured the composite elastic modulus of the cellular and extracellular matrix layers in the blastula wall of Strongylocentrotus purpuratus embryos at the mesenchyme blastula stage. Combined, these two layers exhibit a viscoelastic response with an initial stiffness ranging from 600 to 2300 Pa. To identify the cellular structures responsible for this stiffness we disrupted these structures and correlated the resulting lesions to changes in the elastic modulus. We treated embryos with cytochalasin D to disrupt the actin-based cytoskeleton, nocodazole to disrupt the microtubule-based cytoskeleton, and a gentle glycine extraction to disrupt the apical extracellular matrix (ECM). Embryos treated less than 60 min in cytochalasin D showed no change in their time-dependent elastic modulus even though F-actin was severely disrupted. Similarly, nocodazole had no effect on the elastic modulus even as the microtubules were severely disrupted. However, glycine extraction resulted in a 40 to 50% decrease in the elastic modulus along with a dramatic reduction in the hyalin protein at the apical ECM, thus implicating the apical ECM as a major mechanical component of the blastula wall. This finding bears on the mechanical plausibility of several models for primary invagination.
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Affiliation(s)
- L A Davidson
- Graduate Group in Biophysics, University of California at Berkeley, Berkeley, California, 94720, USA.
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Siddiqui RA, Akard LP, Garcia JGN, Cui Y, English D. Chemotactic Migration Triggers IL-8 Generation in Neutrophilic Leukocytes. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.2.1077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Neutrophils recovered from inflammatory exudates possess increased levels of IL-8, but exposure of neutrophils to chemoattractants results in only a modest stimulation of IL-8 generation. This study was undertaken to explore the hypothesis that IL-8 generation in these cells is dependent upon the process of migration. Neutrophils synthesized up to 30 times as much IL-8 during migration in response to a gradient of diverse chemoattractants than they did when stimulated directly by the attractants in the absence of a gradient. This IL-8 response was dependent on migration since it was not observed in cells exposed to concentration gradients of chemoattractants under conditions that prevented cell movement. While actinomycin-D (1 μg/ml) had little influence on the generation of IL-8 during chemotaxis, the protein synthesis inhibitor cycloheximide (10 μg/ml) markedly blunted the accumulation of cell-associated IL-8, suggesting that new protein synthesis from preexisting mRNA was responsible for the effect. Consistent with this interpretation, migrating cells incorporated over 10 times as much [3H]leucine into IL-8 as did nonmotile neutrophils exposed to chemoattractants. A substantial portion of the IL-8 generated during chemotaxis was released upon subsequent metabolic stimulation. Thus, the IL-8 synthesized during chemotaxis is uniquely positioned to exert a regulatory influence on inflammatory processes governed by neutrophilic leukocytes responding to inflammatory and infectious stimuli.
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Affiliation(s)
- Rafat A. Siddiqui
- *Experimental Cell Research Program, Methodist Research Institute, and
- †Department of Biology, Indiana University/Purdue University, Indianapolis, IN 46201; and Departments of
| | - Luke P. Akard
- *Experimental Cell Research Program, Methodist Research Institute, and
| | | | - Yi Cui
- *Experimental Cell Research Program, Methodist Research Institute, and
| | - Denis English
- *Experimental Cell Research Program, Methodist Research Institute, and
- §Allied Health Sciences, Indiana University School of Medicine, Indianapolis, IN 46202
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Lynn EG, Choy PC, Magil A, O K. Uptake and metabolism of lipoprotein-X in mesangial cells. Mol Cell Biochem 1997; 175:187-94. [PMID: 9350051 DOI: 10.1023/a:1006865420286] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Progressive glomerulosclerosis is a major complication in patients with familial lecithin:cholesterol acyltransferase (LCAT) deficiency. The lack of LCAT activity results in the accumulation of an abnormal lipoprotein, lipoprotein-X (Lp-X), in the plasma of these patients. Lipoprotein-X contains high levels of unesterified cholesterol and phosphatidylcholine. Lp-X may play a role in the accumulation of lipids in the kidney, which in turn may lead to glomerulosclerosis. The objective of this study is to examine the uptake and metabolism of Lp-X by rat mesangial cells. Our results suggest that Lp-X is taken up by mesangial cells and that the lipids in Lp-X are metabolized. Lysosomes containing unesterified cholesterol and phosphatidylcholine, in a molar ratio similar to Lp-X, were synthesized to investigate the roles individual apolipoproteins (apo CI, II, III and E) play in the uptake of Lp-X. Both apo CI and CIII inhibited its uptake while apo CII (1.5 fold) and E (4 fold) stimulated the uptake of Lp-X. Very low density lipoprotein (VLDL) and low density lipoprotein (LDL) inhibited Lp-X uptake by mesangial cells. However, at higher concentrations of high density lipoprotein (HDL), the uptake of Lp-X was stimulated. Proteoglycans have an important role in regulating the uptake of Lp-X, while cytoskeleton-dependent phagocytosis and the scavenger receptor do not appear to be involved.
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Affiliation(s)
- E G Lynn
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada
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