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Microbes and Infection 2016Two clinical tests - the erythrocyte sedimentation rate and the opsonic index - have long been known to non-specifically detect pathology based on their responsiveness... (Review)
Review
Two clinical tests - the erythrocyte sedimentation rate and the opsonic index - have long been known to non-specifically detect pathology based on their responsiveness to changes in serum proteins. In infections serum levels of specific antibodies increase. However, for healthy subjects Wright held that antibodies contributed minimally to opsonic activity (the complement-enhanced phagocytosis of microorganisms). The activity was present in newborn serum, was increased in the acute phase of an immune response prior to antibody increase, and was less specific. Furthermore, defective opsonization was associated with undue susceptibility to certain infections, for which a genetic basis was later found. With the demonstrations of complement-mediated lysis both of normal cells by foreign (plant) lectins, and of foreign cells (microorganisms) by animal lectins, it now appears that endogenous lectins correspond to the heat-stable component of Wright's serum opsonic activity. His work leads to the lectin pathway of complement activation with specificities limited to the recognition of relatively immutable surface sugars - predictable pathogen characters that contrast with the less predictable targets of the adaptive immune system.
Topics: Allergy and Immunology; Animals; Complement Pathway, Mannose-Binding Lectin; History, 20th Century; Humans; Immunity, Innate; Immunologic Factors; Lectins; Opsonin Proteins
PubMed: 27109231
DOI: 10.1016/j.micinf.2016.04.003 -
Neurobiology of Aging Apr 2019Progression of prion diseases is driven by the accumulation of prions in the brain. Ablation of microglia or deletion of the eat-me-signal, milk-fat globule epidermal...
Progression of prion diseases is driven by the accumulation of prions in the brain. Ablation of microglia or deletion of the eat-me-signal, milk-fat globule epidermal growth factor VIII (Mfge8), accelerates prion pathogenesis, suggesting that microglia defend the brain by phagocytosing prions. Similar to Mfge8, developmental endothelial locus-1 (Del-1) is a secreted protein that acts as an opsonin bridging phagocytes and apoptotic cells to facilitate phagocytosis. We therefore asked whether Del-1 might play a role in controlling prion pathogenesis. We assessed the anti-inflammatory and phagocytosis-promoting functions of Del-1 in prion disease and determined whether Del-1 complements Mfge8 in prion clearance in mice with a C57BL/6J genetic background. We found that Del-1 deficiency did not change prion disease progression or lesion patterns. In addition, prion clearance and scrapie prion protein deposition were unaltered in Del-1-deficient mice. In addition, prion-induced neuroinflammation was not affected by Del-1 deficiency. We conclude that Del-1 is not a major determinant of prion pathogenesis in this context.
Topics: Animals; Calcium-Binding Proteins; Cell Adhesion Molecules; Gene Deletion; Inflammation; Intercellular Signaling Peptides and Proteins; Mice, Inbred C57BL; Mice, Transgenic; Microglia; Phagocytosis; Prion Diseases; Prions
PubMed: 30743056
DOI: 10.1016/j.neurobiolaging.2019.01.003 -
Journal of Visualized Experiments : JoVE Apr 2019A key aspect of the immune response to bacterial colonization of the host is phagocytosis. An opsonophagocytic killing assay (OPKA) is an experimental procedure in which...
A key aspect of the immune response to bacterial colonization of the host is phagocytosis. An opsonophagocytic killing assay (OPKA) is an experimental procedure in which phagocytic cells are co-cultured with bacterial units. The immune cells will phagocytose and kill the bacterial cultures in a complement-dependent manner. The efficiency of the immune-mediated cell killing is dependent on a number of factors and can be used to determine how different bacterial cultures compare with regard to resistance to cell death. In this way, the efficacy of potential immune-based therapeutics can be assessed against specific bacterial strains and/or serotypes. In this protocol, we describe a simplified OPKA that utilizes basic culture conditions and cell counting to determine bacterial cell viability after co-culture with treatment conditions and HL-60 immune cells. This method has been successfully utilized with a number of different pneumococcal serotypes, capsular and acapsular strains, and other bacterial species. The advantages of this OPKA protocol are its simplicity, versatility (as this assay is not limited to antibody treatments as opsonins), and minimization of time and reagents to assess basic experimental groups.
Topics: Bacteria; Biological Assay; Cell Survival; HL-60 Cells; Humans; Opsonin Proteins; Phagocytosis
PubMed: 31009013
DOI: 10.3791/59400 -
Frontiers in Immunology 2018Surfactant protein D (SP-D) is a pattern recognition molecule belonging to the Collectin (collagen-containing C-type lectin) family that has pulmonary as well as...
Surfactant protein D (SP-D) is a pattern recognition molecule belonging to the Collectin (collagen-containing C-type lectin) family that has pulmonary as well as extra-pulmonary existence. In the lungs, it is a well-established opsonin that can agglutinate a range of microbes, and enhance their clearance phagocytosis and super-oxidative burst. It can interfere with allergen-IgE interaction and suppress basophil and mast cell activation. However, it is now becoming evident that SP-D is likely to be an innate immune surveillance molecule against tumor development. SP-D has been shown to induce apoptosis in sensitized eosinophils derived from allergic patients and a leukemic cell line p53 pathway. Recently, SP-D has been shown to suppress lung cancer progression interference with the epidermal growth factor signaling. In addition, a truncated form of recombinant human SP-D has been reported to induce apoptosis in pancreatic adenocarcinoma Fas-mediated pathway in a p53-independent manner. To further establish a correlation between SP-D presence/levels and normal and cancer tissues, we performed a bioinformatics analysis, using Oncomine dataset and the survival analysis platforms Kaplan-Meier plotter, to assess if SP-D can serve as a potential prognostic marker for human lung cancer, in addition to human gastric, breast, and ovarian cancers. We also analyzed immunohistochemically the presence of SP-D in normal and tumor human tissues. We conclude that (1) in the lung, gastric, and breast cancers, there is a lower expression of SP-D than normal tissues; (2) in ovarian cancer, there is a higher expression of SP-D than normal tissue; and (3) in lung cancer, the presence of SP-D could be associated with a favorable prognosis. On the contrary, at non-pulmonary sites such as gastric, breast, and ovarian cancers, the presence of SP-D could be associated with unfavorable prognosis. Correlation between the levels of SP-D and overall survival requires further investigation. Our analysis involves a large number of dataset; therefore, any trend observed is reliable. Despite apparent complexity within the results, it is evident that cancer tissues that produce less levels of SP-D compared to their normal tissue counterparts are probably less susceptible to SP-D-mediated immune surveillance mechanisms infiltrating immune cells.
Topics: Biomarkers, Tumor; Breast Neoplasms; Computational Biology; Computer Simulation; Datasets as Topic; Female; Humans; Lung Neoplasms; Male; Neoplasms; Ovarian Neoplasms; Prognosis; Pulmonary Surfactant-Associated Protein D; RNA, Neoplasm; Stomach Neoplasms; Survival Analysis
PubMed: 30127783
DOI: 10.3389/fimmu.2018.01748 -
Brain, Behavior, and Immunity May 2024Complement is dysregulated in the brain in Alzheimer's Disease and in mouse models of Alzheimer's disease. Each of the complement derived effectors, opsonins,...
Complement is dysregulated in the brain in Alzheimer's Disease and in mouse models of Alzheimer's disease. Each of the complement derived effectors, opsonins, anaphylatoxins and membrane attack complex (MAC), have been implicated as drivers of disease but their relative contributions remain unclarified. Here we have focussed on the MAC, a lytic and pro-inflammatory effector, in the App mouse amyloidopathy model. To test the role of MAC, we back-crossed to generate App mice deficient in C7, an essential MAC component. C7 deficiency ablated MAC formation, reduced synapse loss and amyloid load and improved cognition compared to complement-sufficient App mice at 8-10 months age. Adding back C7 caused increased MAC formation in brain and an acute loss of synapses in C7-deficient App mice. To explore whether C7 was a viable therapeutic target, a C7-blocking monoclonal antibody was administered systemically for one month in App mice aged 8-9 months. Treatment reduced brain MAC and amyloid deposition, increased synapse density and improved cognitive performance compared to isotype control-treated App mice. The findings implicate MAC as a driver of pathology and highlight the potential for complement inhibition at the level of MAC as a therapy in Alzheimer's disease.
Topics: Mice; Animals; Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Cognitive Dysfunction; Mice, Transgenic; Plaque, Amyloid; Brain; Cognition; Complement Activation; Disease Models, Animal
PubMed: 38485063
DOI: 10.1016/j.bbi.2024.03.017 -
Clinical and Vaccine Immunology : CVI Feb 2017Plasmodium falciparum malaria remains the deadliest parasitic disease worldwide. Vaccines targeting the preerythrocytic sporozoite and liver stages have the potential to...
Plasmodium falciparum malaria remains the deadliest parasitic disease worldwide. Vaccines targeting the preerythrocytic sporozoite and liver stages have the potential to entirely prevent blood-stage infection and disease, as well as onward transmission. Sporozoite surface and secreted proteins are leading candidates for inclusion in a preerythrocytic stage-specific, antibody-based vaccine. Preclinical functional assays to identify humoral correlates of protection in vitro and to validate novel sporozoite protein targets for inclusion in multisubunit vaccines currently do not consider the interaction of sporozoite-targeting antibodies with other components of the immune system. Here, we describe the development of a simple flow cytometric assay to quantitatively assess the ability of antibodies directed against P. falciparum sporozoites to facilitate their phagocytosis. We demonstrate that this sporozoite opsonic phagocytosis assay (SOPA) is compatible with both monoclonal antibodies and human immune serum and can be performed using cryopreserved P. falciparum sporozoites. This simple, accessible assay will aid with the assessment of antibody responses to vaccination with Plasmodium antigens and their interaction with phagocytic cells of the immune system.
Topics: Antibodies, Protozoan; Flow Cytometry; Humans; Immunoassay; Opsonin Proteins; Phagocytosis; Plasmodium falciparum; Sporozoites
PubMed: 27881488
DOI: 10.1128/CVI.00445-16 -
Scientific Reports Jan 2023The complement system provides vital immune protection against infectious agents by labeling them with complement fragments that enhance phagocytosis by immune cells....
The complement system provides vital immune protection against infectious agents by labeling them with complement fragments that enhance phagocytosis by immune cells. Many details of complement-mediated phagocytosis remain elusive, partly because it is difficult to study the role of individual complement proteins on target surfaces. Here, we employ serum-free methods to couple purified complement C3b onto E. coli bacteria and beads and then expose human neutrophils to these C3b-coated targets. We examine the neutrophil response using a combination of flow cytometry, confocal microscopy, luminometry, single-live-cell/single-target manipulation, and dynamic analysis of neutrophil spreading on opsonin-coated surfaces. We show that purified C3b can potently trigger phagocytosis and killing of bacterial cells via Complement receptor 1. Comparison of neutrophil phagocytosis of C3b- versus antibody-coated beads with single-bead/single-target analysis exposes a similar cell morphology during engulfment. However, bulk phagocytosis assays of C3b-beads combined with DNA-based quenching reveal that these are poorly internalized compared to their IgG1 counterparts. Similarly, neutrophils spread slower on C3b-coated compared to IgG-coated surfaces. These observations support the requirement of multiple stimulations for efficient C3b-mediated uptake. Together, our results establish the existence of a direct pathway of phagocytic uptake of C3b-coated targets and present methodologies to study this process.
Topics: Humans; Neutrophils; Complement C3b; Escherichia coli; Phagocytosis; Receptors, Complement 3b; Complement System Proteins; Immunoglobulin G; Receptors, Complement
PubMed: 36609665
DOI: 10.1038/s41598-022-27279-4 -
Biomaterials Nov 2015Au@Fe3O4 Janus particles (JPs) are heteroparticles with discrete domains defined by different materials. Their tunable composition and morphology confer multimodal and...
Au@Fe3O4 Janus particles (JPs) are heteroparticles with discrete domains defined by different materials. Their tunable composition and morphology confer multimodal and versatile capabilities for use as contrast agents and drug carriers in future medicine. Au@Fe3O4 JPs have colloidal properties and surface characteristics leading to interactions with proteins in biological fluids. The resulting protein adsorption layer ("protein corona") critically affects their interaction with living matter. Although Au@Fe3O4 JPs displayed good biocompatibility in a standardized in vitro situation, an in-depth characterization of the protein corona is of prime importance to unravel underlying mechanisms affecting their pathophysiology and biodistribution in vitro and in vivo. Here, we comparatively analyzed the human plasma corona of Au-thiol@Fe3O4-SiO2-PEG JPs (NH2-functionalized and non-functionalized) and spherical magnetite (Fe3O4-SiO2-PEG) particles and investigated its effects on colloidal stability, biocompatibility and cellular uptake. Label-free quantitative proteomic analyses revealed that complex coronas including almost 180 different proteins were formed within only one minute. Remarkably, in contrast to spherical magnetite particles with surface NH2 groups, the Janus structure prevented aggregation and the adhesion of opsonins. This resulted in an enhanced biocompatibility of corona sheathed JPs compared to spherical magnetite particles and corona-free JPs.
Topics: Adsorption; Animals; Blood Proteins; Coated Materials, Biocompatible; Contrast Media; Endothelial Cells; Gold; Humans; Magnetic Resonance Imaging; Magnetite Nanoparticles; Mice; Multimodal Imaging; Nanocapsules; Particle Size; Surface Properties; Tissue Distribution; Tomography, X-Ray Computed
PubMed: 26276693
DOI: 10.1016/j.biomaterials.2015.07.049 -
European Journal of Immunology Apr 2019Efferocytosis is essential for homeostasis and prevention of the inflammatory and autoimmune diseases resulting from apoptotic cell lysis. CD93 is a transmembrane...
Efferocytosis is essential for homeostasis and prevention of the inflammatory and autoimmune diseases resulting from apoptotic cell lysis. CD93 is a transmembrane glycoprotein previously implicated in efferocytosis, with mutations in CD93 predisposing patients to efferocytosis-associated diseases. CD93 is a cell surface protein, which is proteolytically shed under inflammatory conditions, but it is unknown how CD93 mediates efferocytosis or whether its efferocytic activity is mediated by the soluble or membrane-bound form. Herein, using cell lines and human monocytes and macrophages, we demonstrate that soluble CD93 (sCD93) potently opsonizes apoptotic cells but not a broad range of microorganisms, whereas membrane-bound CD93 has no phagocytic, efferocytic, or tethering activity. Using mass spectrometry, we identified α β as the receptor that recognizes sCD93, and via deletion mutagenesis determined that sCD93 binds to apoptotic cells via its C-type lectin-like domain and to α β by its EGF-like repeats. The bridging of apoptotic cells to α β markedly enhanced efferocytosis by macrophages and was abrogated by α β knockdown. Combined, these data elucidate the mechanism by which CD93 regulates efferocytosis and identifies a previously unreported opsonin-receptor system utilized by phagocytes for the efferocytic clearance of apoptotic cells.
Topics: Animals; Apoptosis; Biomarkers; CHO Cells; Cell Line; Cricetulus; HEK293 Cells; Humans; Integrins; Macrophages; Membrane Glycoproteins; Opsonin Proteins; Protein Binding; Receptors, Complement; Recombinant Proteins
PubMed: 30656676
DOI: 10.1002/eji.201847801 -
Marine Drugs Feb 2022Crustin are a family of antimicrobial peptides that play an important role in protecting against pathogens infection in the innate immune system of crustaceans....
Crustin are a family of antimicrobial peptides that play an important role in protecting against pathogens infection in the innate immune system of crustaceans. Previously, we identified several novel types of crustins, including type VI and type VII crustins. However, their immune functions were still unclear. In the present study, the immune function of type VII crustin LvCrustinVII were investigated in . was wildly expressed in all tested tissues, with relatively high expression levels in hepatopancreas, epidermis and lymphoid organ. Upon infection, was significantly upregulated in hepatopancreas. Recombinant LvCrustinVII (rLvCrustinVII) showed strong inhibitory activities against Gram-negative bacteria and , while weak activities against the Gram-positive bacteria . Binding assay showed that rLvCrustinVII could bind strongly to and , as well as the cell wall components Glu, LPS and PGN. In the presence of Ca, rLvCrustinVII could agglutinate and enhance hemocyte phagocytosis. The present data partially illustrate the immune function of , which enrich our understanding on the functional mechanisms of crustins and provide useful information for application of this kind of antimicrobial peptides.
Topics: Agglutination; Animals; Antimicrobial Cationic Peptides; Arthropod Proteins; Bacteria; Epidermis; Hemocytes; Hepatopancreas; Opsonin Proteins; Penaeidae; Phagocytosis; Recombinant Proteins
PubMed: 35323456
DOI: 10.3390/md20030157