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Brain, Behavior, and Immunity Oct 2014Abnormal accumulations of amyloid-β (Aβ)-peptides are one of the pathological hallmarks of Alzheimer's disease (AD). The precursor of the Aβ-peptides, the amyloid... (Comparative Study)
Comparative Study
Abnormal accumulations of amyloid-β (Aβ)-peptides are one of the pathological hallmarks of Alzheimer's disease (AD). The precursor of the Aβ-peptides, the amyloid precursor protein (APP), is also found in peripheral blood cells, but its function in these cells remains elusive. We previously observed that mononuclear phagocytes release Aβ-peptides during activation and phagocytosis, suggesting a physiologic role in inflammatory processes. Here, we show that supplementing the media with soluble N-terminally truncated Aβ(2-40) and Aβ(2-42) as well as Aβ(1-42) induced the phagocytosis of polystyrene particles (PSPs) by primary human monocytes. If the PSPs were pre-incubated with Aβ-peptides, phagocytosis was induced by all tested Aβ-peptide species. N-terminally truncated Aβ(x-42) induced the phagocytosis of PSPs significantly more effectively than did Aβ(x-40). Similarly, the phagocytosis of Escherichia coli by GM-CSF- and M-CSF-elicited macrophages as well as microglia was particularly facilitated by pre-incubation with N-terminally truncated Aβ(x-42). The proinflammatory polarization of monocytes was indicated by the reduced MSRI expression and IL-10 secretion after phagocytosis of PSPs coated with Aβ(1-42), Aβ(2-42) and Aβ(3p-42). Polarization of the macrophages by GM-CSF reduced the phagocytic activity, but it did not affect the capabilities of Aβ-peptides to opsonize prey. Taken together, Aβ-peptides support phagocytosis as soluble factors and act as opsonins. Differential effects among the Aβ-peptide variants point to distinct mechanisms of interaction among monocytes/macrophages, prey and Aβ-peptides. A proinflammatory polarization induced by the phagocytosis of Aβ-peptide coated particles may provide a model for the chronic inflammatory reaction and sustained plaque deposition in AD.
Topics: Amyloid beta-Peptides; Animals; Cell Line; Escherichia coli; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Interleukin-10; Macrophage Activation; Macrophage Colony-Stimulating Factor; Macrophages; Microglia; Microspheres; Monocytes; Nitric Oxide Synthase Type II; Opsonin Proteins; Peptide Fragments; Phagocytosis; Protein Processing, Post-Translational; Protein Structure, Tertiary; Pyrrolidonecarboxylic Acid; Structure-Activity Relationship; Sus scrofa; Swine
PubMed: 24876064
DOI: 10.1016/j.bbi.2014.05.003 -
Journal of Microbiology, Immunology,... Feb 2011Several elements in colostrum and human milk, including antibodies and nonspecific factors with bactericidal and antiviral activity, may play an important...
BACKGROUND
Several elements in colostrum and human milk, including antibodies and nonspecific factors with bactericidal and antiviral activity, may play an important anti-infectious and protective role. In developing countries, enterotoxigenic Escherichia coli (ETEC) is the main etiological agent of diarrhea in low-socioeconomic level children. In the present work, we studied the functional activity of mononuclear (MN) and polymorphonuclear (PMN) phagocytes of human colostrum against ETEC, as well as the interactions between these cells and colostral or serum opsonins.
METHODS
Colostrum samples were collected from 33 clinically healthy women between 48 and 72 hours postpartum. We verified superoxide release in colostral MN and PMN using cytochrome C reduction methods, phagocytosis, and bactericidal activity using acridine orange methods and superoxide dismutase (SOD) in the colostrum supernatants.
RESULTS
Colostral MN and PMN phagocytes exposed to ETEC opsonized with colostrum supernatants caused a significant increase (p<0.05) in superoxide release. Phagocytosis by colostral PMN cells increased significantly (p<0.5) when the phagocytes were incubated with both sources of opsonins (sera and colostrum). Increases in superoxide release in the presence of opsonized bacteria triggered the bactericidal activity of the phagocytes. Phagocyte treatment with SOD decreased their ability to eliminate ETEC. Colostrum supernatant had higher SOD concentrations (p<0.05) compared with normal human sera.
CONCLUSIONS
These results suggest that the ability of phagocytes to eliminate ETEC depends on the activation of cellular oxidative metabolism; moreover, activation of colostral phagocytes is likely an additional breast-feeding protection mechanism against intestinal infections in infants.
Topics: Adolescent; Adult; Colostrum; Enterotoxigenic Escherichia coli; Female; Humans; Microbial Viability; Opsonin Proteins; Phagocytes; Phagocytosis; Superoxide Dismutase; Superoxides; Young Adult
PubMed: 21531345
DOI: 10.1016/j.jmii.2011.01.002 -
Infection and Immunity Mar 1988
Review
Topics: Animals; Bacterial Physiological Phenomena; Blood Bactericidal Activity; Fimbriae, Bacterial; Humans; Lectins; Macrophages; Opsonin Proteins; Phagocytes; Phagocytosis
PubMed: 2893771
DOI: 10.1128/iai.56.3.539-547.1988 -
Nature Communications Apr 2022Complement activation on cell surfaces leads to the massive deposition of C3b, iC3b, and C3dg, the main complement opsonins. Recognition of iC3b by complement receptor...
Complement activation on cell surfaces leads to the massive deposition of C3b, iC3b, and C3dg, the main complement opsonins. Recognition of iC3b by complement receptor type 3 (CR3) fosters pathogen opsonophagocytosis by macrophages and the stimulation of adaptive immunity by complement-opsonized antigens. Here, we present the crystallographic structure of the complex between human iC3b and the von Willebrand A inserted domain of the α chain of CR3 (αI). The crystal contains two composite interfaces for CR3 αI, encompassing distinct sets of contiguous macroglobulin (MG) domains on the C3c moiety, MG1-MG2 and MG6-MG7 domains. These composite binding sites define two iC3b-CR3 αI complexes characterized by specific rearrangements of the two semi-independent modules, C3c moiety and TED domain. Furthermore, we show the structure of iC3b in a physiologically-relevant extended conformation. Based on previously available data and novel insights reported herein, we propose an integrative model that reconciles conflicting facts about iC3b structure and function and explains the molecular basis for iC3b selective recognition by CR3 on opsonized surfaces.
Topics: Binding Sites; CD11b Antigen; Complement C3b; Complement System Proteins; Humans; Macrophage-1 Antigen; Opsonin Proteins
PubMed: 35413960
DOI: 10.1038/s41467-022-29580-2 -
The European Respiratory Journal Feb 2010Serine proteases released from neutrophils are central to the pathogenesis of cystic fibrosis lung disease and are considered to be obvious therapeutic targets....
Serine proteases released from neutrophils are central to the pathogenesis of cystic fibrosis lung disease and are considered to be obvious therapeutic targets. Neutrophil elastase digests key opsonins present in the lung and disrupts phagocytosis, allowing bacteria to persist despite established pulmonary inflammation. We have found that cathepsin G, an abundant serine protease found in human and murine neutrophils, has other roles in the development of suppurative lung diseases. Murine models of endobronchial inflammation indicate that cathepsin G inhibits airway defences and interferes with the host's ability to clear Pseudomonas aeruginosa from the lung with effects distinct from neutrophil elastase. We hypothesise that differences in bacterial killing are due to defects in innate defences created by proteolysis. Protein profiles of bronchoalveolar lavage of infected wild-type and cathepsin G-deficient mice were compared using two-dimensional polyacrylamide gel electrophoresis and tandem mass spectrometry. Four proteins in bronchoalveolar lavage were cleaved by cathepsin G. Serum amyloid P component leaked into the lung during acute infection and was digested by cathepsin G. Its cleavage products had greater binding to lipopolysaccharide and interfered with phagocytosis. These results indicate that cleaved serum amyloid P component acts as an anti-opsonin and interferes with bacterial clearance from the lung.
Topics: Animals; Bronchi; Bronchoalveolar Lavage; Cathepsin G; Electrophoresis, Gel, Two-Dimensional; HL-60 Cells; Humans; Lung; Mice; Mice, Transgenic; Neutrophils; Opsonin Proteins; Phagocytosis; Serum Amyloid P-Component; Tandem Mass Spectrometry
PubMed: 19679607
DOI: 10.1183/09031936.00020809 -
PloS One Jan 2011Macrophages can remove antigen from the surface of antibody-coated cells by a process termed trogocytosis. Using live cell microscopy and flow cytometry, we investigated...
Macrophages can remove antigen from the surface of antibody-coated cells by a process termed trogocytosis. Using live cell microscopy and flow cytometry, we investigated the dynamics of trogocytosis by RAW264.7 macrophages of Ramos B cells opsonized with the anti-CD20 monoclonal antibody rituximab. Spontaneous and reversible formation of uropods was observed on Ramos cells, and these showed a strong enrichment in rituximab binding. RAW-Ramos conjugate interfaces were highly enriched in rituximab, and transfer of rituximab to the RAW cells in submicron-sized puncta occurred shortly after cell contact. Membrane from the target cells was concomitantly transferred along with rituximab to a variable extent. We established a flow cytometry-based approach to follow the kinetics of transfer and internalization of rituximab. Disruption of actin polymerization nearly eliminated transfer, while blocking phosphatidylinositol 3-kinase activity only resulted in a delay in its acquisition. Inhibition of Src family kinase activity both slowed acquisition and reduced the extent of trogocytosis. The effects of inhibiting these kinases are likely due to their role in efficient formation of cell-cell conjugates. Selective pre-treatment of Ramos cells with phenylarsine oxide blocked uropod formation, reduced enrichment of rituximab at cell-cell interfaces, and reduced the efficiency of trogocytic transfer of rituximab. Our findings highlight that dynamic changes in target cell shape and surface distribution of antigen may significantly influence the progression and extent of trogocytosis. Understanding the mechanistic determinants of macrophage trogocytosis will be important for optimal design of antibody therapies.
Topics: Animals; Antibodies, Monoclonal, Murine-Derived; Antigens, CD20; B-Lymphocytes; Cell Line; Cell Shape; Flow Cytometry; Kinetics; Macrophages; Mice; Opsonin Proteins; Rituximab
PubMed: 21264210
DOI: 10.1371/journal.pone.0014498 -
International Journal of Nanomedicine 2020Nanoparticles (NPs), upon introduction to the biological systems, become wrapped by serum and cellular proteins constituting the protein corona (PC). This PC contributes...
INTRODUCTION
Nanoparticles (NPs), upon introduction to the biological systems, become wrapped by serum and cellular proteins constituting the protein corona (PC). This PC contributes largely to the NPs' interaction with the biological systems and their subsequent functions. On the one hand, PC can decrease the efficiency of targeting by directing the NPs to the reticuloendothelial system (RES) or by masking the active targeting moieties and decreasing their ability to bind to their target receptors. On the other hand, some components of PC have offered hopes for achieving endogenous targeting.
METHODS
In this study, we aimed at the investigation of the role of the PC in determining the behavior of cRGDyk peptide-unconjugated and -conjugated NPs (uNPs and cNPs) exhibiting different physicochemical properties and their interaction with melanoma on in vitro and in vivo levels. Mathematical modeling has been utilized to understand the kinetics of the interaction of NPs with the tumor cells and different organs, respectively.
RESULTS
Endocytosis and exocytosis were reported to occur simultaneously for the utilized NPs. The balance was largely dependent on the NPs' physicochemical properties and the role of the PC. In addition, distinct proteins present in the PC (illustrated in the results of the PC analysis in part I) have also determined the patterns of the NPs' distribution in different organs and tissues of the vascular system, the RES system and the target tumot tissue. Vitronectin (VN) was found to mediate higher accumulation in integrin receptor-expressing melanoma cells, while complement 3 protein (C3) and clusterin (CLU), as an opsonin and dysopsonin, respectively, regulated the balance between the RES uptake and blood circulation.
DISCUSSION
PC, if properly modulated by tuning NPs' physicochemical properties, can serve as a potential venue for optimum utilization of NPs in cancer therapy.
Topics: Biological Transport; Humans; Kinetics; Nanoparticles; Opsonin Proteins; Peptides, Cyclic; Protein Corona
PubMed: 33299308
DOI: 10.2147/IJN.S273721 -
The Journal of Biological Chemistry Aug 1998The Hakata antigen is a novel, thermolabile beta2-macroglycoprotein that reacts with sera from patients suffering from systemic lupus erythematosus. In this study we...
The Hakata antigen is a novel, thermolabile beta2-macroglycoprotein that reacts with sera from patients suffering from systemic lupus erythematosus. In this study we present the structure and the function of the Hakata antigen. We have identified cDNA clones encoding the Hakata antigen and analyzed its function. The cDNA included a possible open reading frame of 897 nucleotides, encoding 299 amino acids. The Hakata antigen consisted of a collagen-like domain in the middle section and a fibrinogen-like domain in the COOH terminus, both of which are homologous to human ficolin-1 and opsonin P35, indicating that these three molecules form a distinct family. The molecular mass of the Hakata antigen expressed in transfected cells was 35 kDa under reduced conditions, and it formed ladder bands under nonreducing conditions compatible with the previous result that the Hakata antigen exists in serum as homopolymers. Purified Hakata antigen sustained lectin activity, showing affinity with GalNAc, GlcNAc, D-fucose as mono/oligosaccharide, and lipopolysaccharides from Salmonella typhimurium and Salmonella minnesota. These results suggest that the Hakata antigen, a new member of the ficolin/opsonin P35 family, plays a role in the serum exerting lectin activity under physiological conditions.
Topics: Amino Acid Sequence; Base Sequence; Carrier Proteins; Cell Line; Cloning, Molecular; DNA, Complementary; Glycoproteins; Humans; Lectins; Microscopy, Electron; Molecular Sequence Data; Opsonin Proteins; Sequence Homology, Amino Acid; Transfection; Ficolins
PubMed: 9694814
DOI: 10.1074/jbc.273.33.20721 -
Infection and Immunity Oct 2013Host defense peptides are immediate responders of the innate immunity that express antimicrobial, immunoregulatory, and wound-healing activities. Neutrophils are a major...
Host defense peptides are immediate responders of the innate immunity that express antimicrobial, immunoregulatory, and wound-healing activities. Neutrophils are a major source for oral host defense peptides, and phagocytosis by neutrophils is a major mechanism for bacterial clearance in the gingival tissue. Dysfunction of or reduction in the numbers of neutrophils or deficiency in the LL-37 host defense peptide was each previously linked with proliferation of oral Aggregatibacter actinomycetemcomitans which resulted in an aggressive periodontal disease. Surprisingly, A. actinomycetemcomitans shows resistance to high concentrations of LL-37. In this study, we demonstrated that submicrocidal concentrations of LL-37 inhibit biofilm formation by A. actinomycetemcomitans and act as opsonins and agglutinins that greatly enhance its clearance by neutrophils and macrophages. Improved uptake of A. actinomycetemcomitans by neutrophils was mediated by their opsonization with LL-37. Enhanced phagocytosis and killing of A. actinomycetemcomitans by murine macrophage-like RAW 264.7 cells were dependent on their preagglutination by LL-37. Although A. actinomycetemcomitans is resistant to the bactericidal effect of LL-37, our results offer a rationale for the epidemiological association between LL-37 deficiency and the expansion of oral A. actinomycetemcomitans and indicate a possible therapeutic use of cationic peptides for host defense.
Topics: Antimicrobial Cationic Peptides; Biofilms; Dose-Response Relationship, Drug; Opsonin Proteins; Pasteurellaceae; Protein Binding; Cathelicidins
PubMed: 23836819
DOI: 10.1128/IAI.01288-12 -
PLoS Neglected Tropical Diseases Aug 2014Infection of susceptible hosts by the encapsulated Gram-negative bacterium Burkholderia pseudomallei (Bp) causes melioidosis, with septic patients attaining mortality...
Delineating the importance of serum opsonins and the bacterial capsule in affecting the uptake and killing of Burkholderia pseudomallei by murine neutrophils and macrophages.
Infection of susceptible hosts by the encapsulated Gram-negative bacterium Burkholderia pseudomallei (Bp) causes melioidosis, with septic patients attaining mortality rates ≥ 40%. Due to its high infectivity through inhalation and limited effective therapies, Bp is considered a potential bioweapon. Thus, there is great interest in identifying immune effectors that effectively kill Bp. Our goal is to compare the relative abilities of murine macrophages and neutrophils to clear Bp, as well as determine the importance of serum opsonins and bacterial capsule. Our findings indicate that murine macrophages and neutrophils are inherently unable to clear either unopsonized Bp or the relatively-avirulent acapsular bacterium B. thailandensis (Bt). Opsonization of Bp and Bt with complement or pathogen-specific antibodies increases macrophage-uptake, but does not promote clearance, although antibody-binding enhances complement deposition. In contrast, complement opsonization of Bp and Bt causes enhanced uptake and killing by neutrophils, which is linked with rapid ROS induction against bacteria exhibiting a threshold level of complement deposition. Addition of bacteria-specific antibodies enhances complement deposition, but antibody-binding alone cannot elicit neutrophil clearance. Bp capsule provides some resistance to complement deposition, but is not anti-phagocytic or protective against reactive oxygen species (ROS)-killing. Macrophages were observed to efficiently clear Bp only after pre-activation with IFNγ, which is independent of serum- and/or antibody-opsonization. These studies indicate that antibody-enhanced complement activation is sufficient for neutrophil-clearance of Bp, whereas macrophages are ineffective at clearing serum-opsonized Bp unless pre-activated with IFNγ. This suggests that effective immune therapies would need to elicit both antibodies and Th1-adaptive responses for successful prevention/eradication of melioidosis.
Topics: Animals; Bacterial Capsules; Blood Bactericidal Activity; Burkholderia pseudomallei; Cells, Cultured; Complement System Proteins; Female; Humans; Interferon-gamma; Macrophages; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Neutrophils; Opsonin Proteins; Phagocytosis; Reactive Oxygen Species
PubMed: 25144195
DOI: 10.1371/journal.pntd.0002988