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Cell Biochemistry and Function Dec 2023Opsonization plays a pivotal role in hindering controlled drug release from nanoformulations due to macrophage-mediated nanoparticle destruction. While first and... (Review)
Review
Opsonization plays a pivotal role in hindering controlled drug release from nanoformulations due to macrophage-mediated nanoparticle destruction. While first and second-generation delivery systems, such as lipoplexes (50-150 nm) and quantum dots, hold immense potential in revolutionizing disease treatment through spatiotemporal controlled drug delivery, their therapeutic efficacy is restricted by the selective labeling of nanoparticles for uptake by reticuloendothelial system and mononuclear phagocyte system via various molecular forces, such as electrostatic, hydrophobic, and van der Waals bonds. This review article presents novel insights into surface-modification techniques utilizing macromolecule-mediated approaches, including PEGylation, di-block copolymerization, and multi-block polymerization. These techniques induce stealth properties by generating steric forces to repel micromolecular-opsonins, such as fibrinogen, thereby mitigating opsonization effects. Moreover, advanced biological methods, like cellular hitchhiking and dysopsonic protein adsorption, are highlighted for their potential to induce biological camouflage by adsorbing onto the nanoparticulate surface, leading to immune escape. These significant findings pave the way for the development of long-circulating next-generation nanoplatforms capable of delivering superior therapy to patients. Future integration of artificial intelligence-based algorithms, integrated with nanoparticle properties such as shape, size, and surface chemistry, can aid in elucidating nanoparticulate-surface morphology and predicting interactions with the immune system, providing valuable insights into the probable path of opsonization.
Topics: Humans; Polyethylene Glycols; Opsonization; Artificial Intelligence; Drug Delivery Systems; Opsonin Proteins; Nanoparticles
PubMed: 37933222
DOI: 10.1002/cbf.3880 -
Microbiology Spectrum Aug 2023Mycobacterium abscessus, an intracellular nontuberculous mycobacterium, is considered the most pathogenic species among the group of rapidly growing mycobacteria. The...
Mycobacterium abscessus, an intracellular nontuberculous mycobacterium, is considered the most pathogenic species among the group of rapidly growing mycobacteria. The resistance of M. abscessus to the host innate response contributes to its pathogenicity in addition to several virulence factors. We have recently shown in that antimicrobial peptides (AMPs), whose production is induced by M. abscessus, are unable to control mycobacterial infection. This could be due to their inability to kill mycobacteria and/or the hidden location of the pathogen in phagocytic cells. Here, we demonstrate that the rapid internalization of M. abscessus by macrophages allows it to escape the AMP-mediated humoral response. By depleting phagocytes in AMP-deficient flies, we found that several AMPs were required for the control of extracellular M. abscessus. This was confirmed in the Tep4 opsonin-deficient flies, which we show can better control M. abscessus growth and have increased survival through overproduction of some AMPs, including Defensin. Furthermore, Defensin alone was sufficient to kill extracellular M. abscessus both and and control its infection. Collectively, our data support that Tep4-mediated opsonization of M. abscessus allows its escape and resistance toward the Defensin bactericidal action in . Mycobacterium abscessus, an opportunistic pathogen in cystic fibrosis patients, is the most pathogenic species among the fast-growing mycobacteria. How M. abscessus resists the host innate response before establishing an infection remains unclear. Using , we have recently demonstrated that M. abscessus resists the host innate response by surviving the cytotoxic lysis of the infected phagocytes and the induced antimicrobial peptides (AMPs), including Defensin. In this work, we demonstrate that M. abscessus resists the latter response by being rapidly internalized by phagocytes. Indeed, by combining and approaches, we show that Defensin is able to control extracellular M. abscessus infection through a direct bactericidal action. In conclusion, we report that M. abscessus escapes the host AMP-mediated humoral response by taking advantage of its internalization by the phagocytes.
Topics: Animals; Mycobacterium abscessus; Drosophila; Opsonization; Mycobacterium; Antimicrobial Peptides; Defensins; Mycobacterium Infections, Nontuberculous; Anti-Bacterial Agents
PubMed: 37260399
DOI: 10.1128/spectrum.00777-23 -
Microbiology Spectrum Feb 2023Nontuberculous mycobacteria (NTM), including Mycobacterium avium, are clinically important pathogens in cystic fibrosis (CF). The innate immune response to M. avium...
Nontuberculous mycobacteria (NTM), including Mycobacterium avium, are clinically important pathogens in cystic fibrosis (CF). The innate immune response to M. avium remains incompletely understood. We evaluated the role of complement opsonization in neutrophil-mediated killing of M. avium. Killing assays were performed using neutrophils from healthy donors (HDs) and persons with CF (pwCF). Clinical isolates of M. avium were opsonized with plasma from HDs or pwCF, which was intact or heat-treated to inactivate complement. HD neutrophils had killing activity against M. avium opsonized with intact HD plasma and killing was significantly reduced when M. avium was opsonized with heat-inactivated HD plasma. When opsonized with HD plasma, CF neutrophils had killing activity against M. avium that was not different than HD neutrophils. When opsonized with intact plasma from pwCF, HD neutrophil killing of M. avium was significantly reduced. Opsonization of M. avium with C3-depleted serum or IgM-depleted plasma resulted in significantly reduced killing. Plasma C3 levels were elevated in pwCF with NTM infection compared to pwCF without NTM infection. These studies demonstrate that human neutrophils efficiently kill M. avium when opsonized in the presence of plasma factors from HD that include C3 and IgM. Killing efficiency is significantly lower when the bacteria are opsonized with plasma from pwCF. This indicates a novel role for opsonization in neutrophil killing of M. avium and a deficiency in complement opsonization as a mechanism of impaired M. avium killing in CF. Mycobacterium avium is a member of a group of bacterial species termed nontuberculous mycobacteria (NTM) that cause lung disease in certain populations, including persons with cystic fibrosis (CF). NTM infections are challenging to diagnose and can be even more difficult to treat. This study investigated how the immune system responds to M. avium infection in CF. We found that neutrophils, the most abundant immune cell in the lungs in CF, can effectively kill M. avium in individuals both with and without CF. Another component of the immune response called the complement system is also required for this process. Levels of complement proteins are altered in persons with CF who have a history of NTM compared to those without a history of NTM infection. These results add to our understanding of how the immune system responds to M. avium, which can help pave the way toward better diagnostic and treatment strategies.
Topics: Humans; Cystic Fibrosis; Neutrophils; Mycobacterium avium; Opsonization; Mycobacterium Infections, Nontuberculous; Nontuberculous Mycobacteria; Complement System Proteins; Immunoglobulin M
PubMed: 36651756
DOI: 10.1128/spectrum.03279-22 -
Frontiers in Immunology 2021Spike-specific antibodies are central to effective COVID19 immunity. Research efforts have focused on antibodies that neutralize the ACE2-Spike interaction but not on...
Spike-specific antibodies are central to effective COVID19 immunity. Research efforts have focused on antibodies that neutralize the ACE2-Spike interaction but not on non-neutralizing antibodies. Antibody-dependent phagocytosis is an immune mechanism enhanced by opsonization, where typically, more bound antibodies trigger a stronger phagocyte response. Here, we show that Spike-specific antibodies, dependent on concentration, can either enhance or reduce Spike-bead phagocytosis by monocytes independently of the antibody neutralization potential. Surprisingly, we find that both convalescent patient plasma and patient-derived monoclonal antibodies lead to maximum opsonization already at low levels of bound antibodies and is reduced as antibody binding to Spike protein increases. Moreover, we show that this Spike-dependent modulation of opsonization correlate with the outcome in an experimental SARS-CoV-2 infection model. These results suggest that the levels of anti-Spike antibodies could influence monocyte-mediated immune functions and propose that non-neutralizing antibodies could confer protection to SARS-CoV-2 infection by mediating phagocytosis.
Topics: Antibodies, Monoclonal; Antibodies, Neutralizing; Antibodies, Viral; COVID-19; Cell Line; HEK293 Cells; Humans; Neutralization Tests; Opsonization; Phagocytosis; SARS-CoV-2; Spike Glycoprotein, Coronavirus
PubMed: 35095897
DOI: 10.3389/fimmu.2021.808932 -
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 -
Proceedings of the National Academy of... Apr 2023Antibodies play a central role in the immune defense against SARS-CoV-2. Emerging evidence has shown that nonneutralizing antibodies are important for immune defense...
Antibodies play a central role in the immune defense against SARS-CoV-2. Emerging evidence has shown that nonneutralizing antibodies are important for immune defense through Fc-mediated effector functions. Antibody subclass is known to affect downstream Fc function. However, whether the antibody subclass plays a role in anti-SARS-CoV-2 immunity remains unclear. Here, we subclass-switched eight human IgG1 anti-spike monoclonal antibodies (mAbs) to the IgG3 subclass by exchanging their constant domains. The IgG3 mAbs exhibited altered avidities to the spike protein and more potent Fc-mediated phagocytosis and complement activation than their IgG1 counterparts. Moreover, combining mAbs into oligoclonal cocktails led to enhanced Fc- and complement receptor-mediated phagocytosis, superior to even the most potent single IgG3 mAb when compared at equivalent concentrations. Finally, in an in vivo model, we show that opsonic mAbs of both subclasses can be protective against a SARS-CoV-2 infection, despite the antibodies being nonneutralizing. Our results suggest that opsonic IgG3 oligoclonal cocktails are a promising idea to explore for therapy against SARS-CoV-2, its emerging variants, and potentially other viruses.
Topics: Humans; Immunoglobulin G; Opsonization; COVID-19; SARS-CoV-2; Phagocytosis; Antibodies, Monoclonal
PubMed: 37011197
DOI: 10.1073/pnas.2217590120 -
Proceedings of the National Academy of... Jan 2022Gram-positive organisms with their thick envelope cannot be lysed by complement alone. Nonetheless, antibody-binding on the surface can recruit complement and mark these...
Gram-positive organisms with their thick envelope cannot be lysed by complement alone. Nonetheless, antibody-binding on the surface can recruit complement and mark these invaders for uptake and killing by phagocytes, a process known as opsonophagocytosis. The crystallizable fragment of immunoglobulins (Fcγ) is key for complement recruitment. The cell surface of is coated with Staphylococcal protein A (SpA). SpA captures the Fcγ domain of IgG and interferes with opsonization by anti- antibodies. In principle, the Fcγ domain of therapeutic antibodies could be engineered to avoid the inhibitory activity of SpA. However, the SpA-binding site on Fcγ overlaps with that of the neonatal Fc receptor (FcRn), an interaction that is critical for prolonging the half-life of serum IgG. This evolutionary adaptation poses a challenge for the exploration of Fcγ mutants that can both weaken SpA-IgG interactions and retain stability. Here, we use both wild-type and transgenic human FcRn mice to identify antibodies with enhanced half-life and increased opsonophagocytic killing in models of infection and demonstrate that antibody-based immunotherapy can be improved by modifying Fcγ. Our experiments also show that by competing for FcRn-binding, staphylococci effectively reduce the half-life of antibodies during infection. These observations may have profound impact in treating cancer, autoimmune, and asthma patients colonized or infected with and undergoing monoclonal antibody treatment.
Topics: Amino Acid Sequence; Antibodies, Bacterial; Antibodies, Monoclonal; Antibody-Dependent Cell Cytotoxicity; Complement Activation; Dose-Response Relationship, Drug; Dose-Response Relationship, Immunologic; Humans; Opsonization; Phagocytosis; Protein Binding; Protein Engineering; Protein Interaction Domains and Motifs; Receptors, Fc; Staphylococcal Protein A; Staphylococcus aureus
PubMed: 35058363
DOI: 10.1073/pnas.2114478119 -
Nano Letters Aug 2022Folic acid (FA) is one of the most widely utilized small-molecule ligands for cancer targeted drug delivery. Natural IgM was recently found to avidly absorb on the...
Folic acid (FA) is one of the most widely utilized small-molecule ligands for cancer targeted drug delivery. Natural IgM was recently found to avidly absorb on the surface of FA-functionalized liposomes (FA-sLip), negatively regulating the performance by efficiently activating complement. Herein, FA-functionalized lipodiscs (FA-Disc) were constructed to successfully circumvent IgM-mediated opsonization and retained binding activity with folate receptors . The FA moiety along with the bound IgM was restricted to the highly curved rim of lipodiscs, leading to IgM incapability of presenting the membrane-bound conformation to trigger complement activation. The C1q docking, C3 binding, and C5a release were blocked and accelerated blood clearance phenomenon was mitigated of FA-Disc. FA-Disc retained folate binding activity and could effectively target folate receptor positive tumors . The present study provides a useful solution to avoid the negative regulation by IgM and achieve FA-enabled targeting by exploring disc-shaped nanocarriers.
Topics: Cell Line, Tumor; Drug Delivery Systems; Folic Acid; Humans; Immunoglobulin M; Liposomes; Nanoparticles; Neoplasms; Opsonization
PubMed: 35943299
DOI: 10.1021/acs.nanolett.2c01509 -
Small (Weinheim An Der Bergstrasse,... Apr 2022Coating nanoparticles with poly(ethylene glycol) (PEG) is widely used to achieve long-circulating properties after infusion. While PEG reduces binding of opsonins to the...
Coating nanoparticles with poly(ethylene glycol) (PEG) is widely used to achieve long-circulating properties after infusion. While PEG reduces binding of opsonins to the particle surface, immunogenic anti-PEG side-effects show that PEGylated nanoparticles are not truly "stealth" to surface active proteins. A major obstacle for understanding the complex interplay between opsonins and nanoparticles is the averaging effects of the bulk assays that are typically applied to study protein adsorption to nanoparticles. Here, a microscopy-based method for directly quantifying opsonization at the single nanoparticle level is presented. Various surface coatings are investigated on liposomes, including PEG, and show that opsonization by both antibodies and complement C3b is highly dependent on the surface chemistry. It is further demonstrated that this opsonization is heterogeneous, with opsonized and non-opsonized liposomes co-existing in the same ensemble. Surface coatings modify the percentage of opsonized liposomes and/or opsonin surface density on the liposomes, with strikingly different patterns for antibodies and complement. Thus, this assay provides mechanistic details about opsonization at the single nanoparticle level previously inaccessible to established bulk assays.
Topics: Antibodies; Complement System Proteins; Liposomes; Opsonin Proteins; Opsonization; Polyethylene Glycols
PubMed: 35187804
DOI: 10.1002/smll.202106529 -
Infection and Immunity Dec 2020Bubonic plague results when is deposited in the skin via the bite of an infected flea. Bacteria then traffic to the draining lymph node (dLN) where they replicate to...
Bubonic plague results when is deposited in the skin via the bite of an infected flea. Bacteria then traffic to the draining lymph node (dLN) where they replicate to large numbers. Without treatment, this infection can result in highly fatal septicemia. Several plague vaccine candidates are currently at various stages of development, but no licensed vaccine is available in the United States. Though polyclonal and monoclonal antibodies (Ab) can provide complete protection against bubonic plague in animal models, the mechanisms responsible for this antibody-mediated immunity (AMI) to remain poorly understood. Here, we examine the effects of Ab opsonization on interactions with phagocytes and Opsonization of with polyclonal antiserum modestly increased phagocytosis/killing by an oxidative burst of murine neutrophils Intravital microscopy (IVM) showed increased association of Ab-opsonized with neutrophils in the dermis in a mouse model of bubonic plague. IVM of popliteal LNs after intradermal (i.d.) injection of bacteria in the footpad revealed increased -neutrophil interactions and increased neutrophil crawling and extravasation in response to Ab-opsonized bacteria. Thus, despite only having a modest effect in assays, opsonizing Ab had a dramatic effect on -neutrophil interactions in the dermis and dLN very early after infection. These data shed new light on the importance of neutrophils in AMI to and may provide a new correlate of protection for evaluation of plague vaccine candidates.
Topics: Animals; Antibodies, Bacterial; Antibody-Dependent Cell Cytotoxicity; Complement System Proteins; Cytokines; Disease Models, Animal; Host-Pathogen Interactions; Immunity, Innate; Lymph Nodes; Mice; Neutrophils; Plague; Reactive Oxygen Species; Skin; Type III Secretion Systems; Yersinia pestis
PubMed: 33077628
DOI: 10.1128/IAI.00061-20