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The Journal of Infectious Diseases Dec 2021Monoclonal antibodies (mAbs) are gaining significant momentum as novel therapeutics for infections caused by antibiotic-resistant bacteria. We evaluated the mechanism by...
Monoclonal antibodies (mAbs) are gaining significant momentum as novel therapeutics for infections caused by antibiotic-resistant bacteria. We evaluated the mechanism by which antibacterial mAb therapy protects against Acinetobacter baumannii infections. Anticapsular mAb enhanced macrophage opsonophagocytosis and rescued mice from lethal infections by harnessing complement, macrophages, and neutrophils; however, the degree of bacterial burden did not correlate with survival. Furthermore, mAb therapy reduced proinflammatory (interleukin-1β [IL-1β], IL-6, tumor necrosis factor-α [TNF-α]) and anti-inflammatory (IL-10) cytokines, which correlated inversely with survival. Although disrupting IL-10 abrogated the survival advantage conferred by the mAb, IL-10-knockout mice treated with mAb could still survive if TNF-α production was suppressed directly (via anti-TNF-α neutralizing antibody) or indirectly (via macrophage depletion). Thus, even for a mAb that enhances microbial clearance via opsonophagocytosis, clinical efficacy required modulation of pro- and anti-inflammatory cytokines. These findings may inform future mAb development targeting bacteria that trigger the sepsis cascade.
Topics: Acinetobacter Infections; Acinetobacter baumannii; Animals; Anti-Bacterial Agents; Antibodies, Monoclonal; Cytokines; Immunomodulation; Interleukin-10; Mice; Opsonization; Tumor Necrosis Factor Inhibitors; Tumor Necrosis Factor-alpha
PubMed: 34036366
DOI: 10.1093/infdis/jiab265 -
Immunology Mar 1979Staphylococcus aureus opsonization was studied kinetically by: (1) determination of the uptake of [3H]-thymidine labelled bacteria by human PMN's; (2) fluorescent...
Staphylococcus aureus opsonization mediated via the classical and alternative complement pathways. A kinetic study using MgEGTA chelated serum and human sera deficient in IgG and complement factors C1s and C2.
Staphylococcus aureus opsonization was studied kinetically by: (1) determination of the uptake of [3H]-thymidine labelled bacteria by human PMN's; (2) fluorescent anti-C3 and anti-IgG staining of opsonized bacteria; and (3) measuring bacterial complement consumption. Maximum opsonization in normal serum occurred within 5 min of incubation. About 80% of staphylococci were then taken up by PMN's, and IgG and C3b could be detected on the bacterial surface. In the absence of a functional classical complement pathway, as in sera deficient in C1s and C2 and in MgEGTA chelated serum, maximal opsonization was only achieved after 30--60 min incubation. Opsonization in IgG deficient serum occurred at a rate similar to that found in C2 deficient or MgEGTA chelated serum. Opsonization was greatly enhanced when sera were reconstituted. It was concluded that in IgG deficient serum Staphylococcus aureus opsonization is mediated via the alternative complement pathway. Dilution of normal serum primarily affected the classical complement pathway, resulting in a decreased rate of opsonization. In normal serum IgG did not appear to be a rate-limiting factor. S. Aureus opsonization was best studied by the phagocytosis assay and the fluorescent-antibody technique. Measuring haemolytic complement consumption was found to be an insensitive indicator of bacterial complement activation and opsonization.
Topics: Complement Activation; Complement C1; Complement C2; Complement Fixation Tests; Complement Pathway, Alternative; Complement Pathway, Classical; Egtazic Acid; Humans; Immunoglobulin G; In Vitro Techniques; Kinetics; Magnesium; Neutrophils; Opsonin Proteins; Phagocytosis; Staphylococcus aureus
PubMed: 108204
DOI: No ID Found -
Frontiers in Immunology 2021Fc receptor (FcR) is an important opsonin receptor on the surface of immune cells, playing an important role in antibody-dependent cell-mediated immunity. Our previous...
Fc receptor (FcR) is an important opsonin receptor on the surface of immune cells, playing an important role in antibody-dependent cell-mediated immunity. Our previous work found that the FcR of flounder showed a marked expression response in phagocytizing IgM B cell, which suggested that FcR might participate in regulating Ig-opsonized phagocytosis. In this paper, in order to elucidate the potential role of FcR in mediating phagocytosis of IgM B cell, flounder anti- serum was prepared and complement-inactivated for the use of opsonization, and the sera of healthy flounder were used as control. Flow cytometric analysis showed that the phagocytosis rates of antiserum-opsonized in peripheral blood mIgM B lymphocytes were significantly higher than the control group, and higher phagocytosis rates of mIgM B lymphocyte could be detected with an increasing incubation time ranging from 1 to 5 h. The phagocytosis rates of antiserum-opsonized by mIgM B lymphocyte for an incubation time of 1, 3 or 5 h were 51.1, 63.0, and 77.5% respectively, which were significantly higher than the phagocytosis rates in the control groups with 40.2, 50.9, and 63.8%, respectively. While the Fc fragment of IgM on the surface of opsonized was blocked by rabbit anti-flounder IgM polyclonal antibodies, phagocytosis rates of mIgM B lymphocyte decreased significantly compared with the unblocked group. Moreover, the proportion of mIgM B lymphocytes with higher intracellular reactive oxygen species (ROS) levels rose to 32.1% from the control level of 23.0% after phagocytosis of antiserum-opsonized . FcγRII and Syk were found to be significantly upregulated, while FcγRIII was significantly downregulated in the mIgM B lymphocytes post phagocytosis. Furthermore, when FcγRII of mIgM B lymphocytes was blocked by the prepared antibodies, their phagocytosis rate of antiserum-opsonized was 39.0%, which was significantly lower than the unblocked group of 54.0%. These results demonstrate that FcR plays a critical role in mediating phagocytosis and bactericidal activity of mIgM B lymphocytes, which would facilitate an improved understanding of the regulatory roles of FcR in phagocytosis of teleost B lymphocytes.
Topics: Animals; B-Lymphocytes; Cells, Cultured; Edwardsiella tarda; Enterobacteriaceae Infections; Fish Proteins; Flounder; Gene Expression Regulation; Host-Pathogen Interactions; Immunity, Innate; Immunoglobulin M; Opsonization; Receptors, Fc; Signal Transduction; Time Factors
PubMed: 34975918
DOI: 10.3389/fimmu.2021.804244 -
PloS One 2011Interaction with the complement system is an underappreciated aspect of HIV-1 infection; even in primary infection, complement fragments are found on virions with...
Interaction with the complement system is an underappreciated aspect of HIV-1 infection; even in primary infection, complement fragments are found on virions with potential to affect the interplay between the virus and dendritic cells (DC). Since opsonization may affect the efficiency of uptake and the type of receptors utilized, we compared the interactions of DC with free HIV-1 (F-HIV) and complement opsonized HIV-1 (C-HIV). We demonstrate that C-HIV significantly enhanced the uptake by immature DC (IDC) and mature DC (MDC) and that the internalization rate was dependent on both opsonization of the virus and DC maturation state. Increased DC uptake of C-HIV was not due to opsonization related increased binding of virus to the surface of DC but rather increased internalization of C-HIV despite utilizing a similar repertoire of receptors as F-HIV. Both F-HIV and C-HIV interacted with C-type lectins, integrins, and CD4 and blocking these receptor families prevented HIV-1 from binding to DC at 4°C. Blocking integrins significantly reduced the binding and uptake of F-HIV and C-HIV implicating the involvement of several integrins such as β1-integrin, CR3, LFA-1, and α4β7. Distinctive for C-HIV was usage of β1-integrin and for F-HIV, usage of β7-integrin, whereas both F-HIV and C-HIV utilized both integrin chains of CR3. We have in this study identified the receptor types used by both F-HIV and C-HIV to bind to DC. Noteworthy, C-HIV was internalized more efficiently by DC than F-HIV, probably via receptor mediated endocytosis, which may entail different intracellular processing of the virus leading to both elevated infection and altered activation of HIV specific immune responses.
Topics: CD4 Antigens; Cell Differentiation; Complement System Proteins; Dendritic Cells; Endocytosis; HIV-1; Humans; Integrins; Kinetics; Lectins, C-Type; Opsonin Proteins; Receptors, Cell Surface; Virion; Virus Internalization
PubMed: 21853149
DOI: 10.1371/journal.pone.0023542 -
Data in Brief Oct 2018The data in the present article are related to research article (doi: https://doi.org/10.1016/j.imlet.2018.04.002) [1]. The data describes the detailed immunization...
The data in the present article are related to research article (doi: https://doi.org/10.1016/j.imlet.2018.04.002) [1]. The data describes the detailed immunization protocol for generating polyclonal antisera to murine erythrocytes in rat. The rat anti-mouse erythrocyte serum is then tested for its ability to bind and opsonize murine erythrocytes. Second set of data confirms the oxidative damage to murine erythrocytes by treatment with different dose of the -butyl hydroperoxide (-BHP) on the basis of phosphotidylserine externalization by murine erythrocytes as well as measurement of reactive oxygen species (ROS) formation in -BHP treated erythrocytes. Third set of data depicts lack of mast cell degranulation in the form of β- hexosaminidase release in response to co-incubation of mast cell with normal and oxidatively damaged erythrocytes. Lastly, the uptake of oxidatively damaged erythrocytes by resting and activated RBL-2H3 mast cells is shown by live cell imaging using confocal microscope.
PubMed: 30263917
DOI: 10.1016/j.dib.2018.08.192 -
American Journal of Veterinary Research Nov 2011To investigate the effect of opsonization of Rhodococcus equi with R. equi-specific antibodies in plasma on bacterial viability and phagocyte activation in a cell...
OBJECTIVE
To investigate the effect of opsonization of Rhodococcus equi with R. equi-specific antibodies in plasma on bacterial viability and phagocyte activation in a cell culture model of infection.
SAMPLE
Neutrophils and monocyte-derived macrophages from 6 healthy 1-week-old foals and 1 adult horse.
PROCEDURES
Foal and adult horse phagocytes were incubated with either opsonized or nonopsonized bacteria. Opsonization was achieved by use of plasma containing high or low concentrations of R. equi-specific antibodies. Phagocyte oxidative burst activity was measured by use of flow cytometry, and macrophage tumor necrosis factor (TNF)-α production was measured via an ELISA. Extracellular and intracellular bacterial viability was measured with a novel R. equi-luciferase construct that used a luminometer.
RESULTS
Opsonized bacteria increased oxidative burst activity in adult horse phagocytes, and neutrophil activity was dependent on the concentration of specific antibody. Secretion of TNF-α was higher in macrophages infected with opsonized bacteria. Opsonization had no significant effect on bacterial viability in macrophages; however, extracellular bacterial viability was decreased in broth containing plasma with R. equi-specific antibodies, compared with viability in broth alone.
CONCLUSIONS AND CLINICAL RELEVANCE
The use of plasma enriched with specific antibodies for the opsonization of R. equi increased the activation of phagocytes and decreased bacterial viability in the extracellular space. Although opsonized R. equi increased TNF-α secretion and oxidative burst in macrophages, additional factors may be necessary for effective intracellular bacterial killing. These data have suggested a possible role of plasma antibody in protection of foals from R. equi pneumonia.
Topics: Actinomycetales Infections; Animals; Animals, Newborn; Antibodies, Bacterial; Bacterial Proteins; Bronchopneumonia; Enzyme-Linked Immunosorbent Assay; Female; Horse Diseases; Horses; Macrophages; Male; Microbial Viability; Neutrophils; Opsonin Proteins; Phagocytes; Phagocytosis; Respiratory Burst; Rhodococcus equi; Tumor Necrosis Factor-alpha
PubMed: 22023124
DOI: 10.2460/ajvr.72.11.1465 -
Journal of Veterinary Internal Medicine Jan 2021Evidence regarding the efficacy of equine hyperimmune plasma to prevent pneumonia in foals caused by Rhodococcus equi is limited and conflicting.
BACKGROUND
Evidence regarding the efficacy of equine hyperimmune plasma to prevent pneumonia in foals caused by Rhodococcus equi is limited and conflicting.
HYPOTHESIS
Opsonization with R. equi-specific hyperimmune plasma (HIP) will significantly increase phagocytosis and decrease intracellular replication of R. equi by alveolar macrophages (AMs) compared to normal plasma (NP).
ANIMALS
Fifteen adult Quarter Horses were used to collect bronchoalveolar lavage cells.
METHODS
In the first experiment, AMs from 9 horses were pretreated (incubated) with either HIP, NP, or media only (control) and then infected with nonopsonized R. equi. In a second experiment, AMs from 6 horses were infected with R. equi either opsonized with HIP or opsonized with NP. For both experiments, AMs were lysed at 0 and 48 hours and the number of viable R. equi quantified by culture were compared among groups using linear mixed-effects modeling with significance set at P < .05.
RESULTS
Opsonization with either HIP or NP increased phagocytosis by AMs (P < .0001) and decreased intracellular survival of organisms in AMs (P < .0001). Pretreating AMs with either HIP or NP without opsonizing R. equi had no effects on phagocytosis or intracellular replication.
CONCLUSIONS AND CLINICAL IMPORTANCE
Opsonizing R. equi with either NP or HIP decreases intracellular survival of organisms in AMs, but the effect does not appear to be enhanced by using HIP. Mechanisms other than effects on AMs must explain any clinical benefits of using HIP over NP to decrease the incidence of R. equi pneumonia in foals.
Topics: Actinomycetales Infections; Animals; Antibodies, Bacterial; Horse Diseases; Horses; Macrophages; Phagocytosis; Rhodococcus; Rhodococcus equi
PubMed: 33326149
DOI: 10.1111/jvim.16002 -
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 -
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 -
Clinical and Vaccine Immunology : CVI Mar 2009The currently available 7-valent pneumococcal conjugate vaccine (PCV7) elicits good immune response to and is effective against vaccine serotypes. However, its...
The currently available 7-valent pneumococcal conjugate vaccine (PCV7) elicits good immune response to and is effective against vaccine serotypes. However, its effectiveness against vaccine-related serotypes is variable. Serum samples were obtained 1 month after the last vaccination from 31 infants immunized with PCV7 at 2, 4, and 6 months of age. The sera were used to determine immunoglobulin G antibody levels to eight serotypes (seven vaccine serotypes and serotype 19A) with enzyme-linked immunosorbent assay (ELISA) and opsonic capacity against 11 serotypes (seven vaccine serotypes, serotypes 19A and 6A, and nonvaccine serotypes 5 and 7F) using a multiplexed opsonization assay. ELISA results showed antibody concentrations varied between 1.84 and 10.49 microg/ml, and all subjects had antibody concentrations of >or=0.35 microg/ml for all serotypes, including serotype 19A. In contrast, the opsonic index was detectable (i.e., opsonic index >or= 8) in all children for the seven vaccine serotypes, 81% for serotype 6A, and merely 19% for serotype 19A. PCV7 shows good immunogenicity for vaccine serotypes in infants after a primary series. PCV7 does not elicit opsonic antibodies to serotype 19A. ELISA may thus be an inadequate surrogate assay for evaluating the response for cross-reactive serotypes in infants.
Topics: Antibodies, Bacterial; Enzyme-Linked Immunosorbent Assay; Heptavalent Pneumococcal Conjugate Vaccine; Humans; Immunoglobulin G; Infant; Opsonin Proteins; Phagocytosis; Pneumococcal Vaccines; Streptococcus pneumoniae
PubMed: 19144787
DOI: 10.1128/CVI.00344-08