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Advanced Materials (Deerfield Beach,... Feb 2022Complement opsonization is among the biggest challenges facing nanomedicine. Nearly instantly after injection into blood, nanoparticles are opsonized by the complement...
Complement opsonization is among the biggest challenges facing nanomedicine. Nearly instantly after injection into blood, nanoparticles are opsonized by the complement protein C3, leading to clearance by phagocytes, fouling of targeting moieties, and release of anaphylatoxins. While surface polymers such as poly(ethylene glycol) (PEG) partially decrease complement opsonization, most nanoparticles still suffer from extensive complement opsonization, especially when linked to targeting moieties. To ameliorate the deleterious effects of complement, two of mammals' natural regulators of complement activation (RCAs), Factors H and I, are here conjugated to the surface of nanoparticles. In vitro, Factor H or I conjugation to PEG-coated nanoparticles decrease their C3 opsonization, and markedly reduce nanoparticle uptake by phagocytes. In an in vivo mouse model of sepsis-induced lung injury, Factor I conjugation abrogates nanoparticle uptake by intravascular phagocytes in the lungs, allowing the blood concentration of the nanoparticle to remain elevated much longer. For nanoparticles targeted to the lung's endothelium by conjugation to anti-ICAM antibodies, Factor I conjugation shifts the cell-type distribution away from phagocytes and toward endothelial cells. Finally, Factor I conjugation abrogates the severe anaphylactoid responses common to many nanoparticles, preventing systemic capillary leak and preserving blood flow to visceral organs and the brain. Thus, conjugation of RCAs, like Factor I, to nanoparticles is likely to help in nanomedicine's long battle against complement, improving several key parameters critical for clinical success.
Topics: Animals; Complement Activation; Complement C3; Complement Factor H; Endothelial Cells; Fibrinogen; Mammals; Mice; Nanomedicine; Nanoparticles; Opsonization
PubMed: 34910334
DOI: 10.1002/adma.202107070 -
ELife Sep 2020HIV transmission via genital and colorectal mucosa are the most common routes of dissemination. Here, we explored the effects of free and complement-opsonized HIV on...
HIV transmission via genital and colorectal mucosa are the most common routes of dissemination. Here, we explored the effects of free and complement-opsonized HIV on colorectal tissue. Initially, there was higher antiviral responses in the free HIV compared to complement-opsonized virus. The mucosal transcriptional response at 24 hr revealed the involvement of activated T cells, which was mirrored in cellular responses observed at 96 hr in isolated mucosal T cells. Further, HIV exposure led to skewing of T cell phenotypes predominantly to inflammatory CD4+ T cells, that is Th17 and Th1Th17 subsets. Of note, HIV exposure created an environment that altered the CD8+ T cell phenotype, for example expression of regulatory factors, especially when the virions were opsonized with complement factors. Our findings suggest that HIV-opsonization alters the activation and signaling pathways in the colorectal mucosa, which promotes viral establishment by creating an environment that stimulates mucosal T cell activation and inflammatory Th cells.
Topics: Adolescent; Adult; Colon; Complement Activation; Complement System Proteins; Female; HIV Infections; HIV-1; Humans; Intestinal Mucosa; Lymphocyte Activation; Male; Opsonin Proteins; T-Lymphocytes; Young Adult
PubMed: 32876566
DOI: 10.7554/eLife.57869 -
Cancers Jul 2022In the past 25 years, a considerable number of therapeutic monoclonal antibodies (mAb) against a variety of tumor-associated antigens (TAA) have become available for the... (Review)
Review
In the past 25 years, a considerable number of therapeutic monoclonal antibodies (mAb) against a variety of tumor-associated antigens (TAA) have become available for the targeted treatment of hematologic and solid cancers. Such antibodies opsonize cancer cells and can trigger cytotoxic responses mediated by Fc-receptor expressing immune cells in the tumor microenvironment (TME). Although frequently ignored, neutrophils, which are abundantly present in the circulation and many cancers, have demonstrated to constitute bona fide effector cells for antibody-mediated tumor elimination in vivo. It has now also been established that neutrophils exert a unique mechanism of cytotoxicity towards antibody-opsonized tumor cells, known as trogoptosis, which involves Fc-receptor (FcR)-mediated trogocytosis of cancer cell plasma membrane leading to a lytic/necrotic type of cell death. However, neutrophils prominently express the myeloid inhibitory receptor SIRPα, which upon interaction with the 'don't eat me' signal CD47 on cancer cells, limits cytotoxicity, forming a mechanism of resistance towards anti-cancer antibody therapeutics. In fact, tumor cells often overexpress CD47, thereby even more strongly restricting neutrophil-mediated tumor killing. Blocking the CD47-SIRPα interaction may therefore potentiate neutrophil-mediated antibody-dependent cellular cytotoxicity (ADCC) towards cancer cells, and various inhibitors of the CD47-SIRPα axis are now in clinical studies. Here, we review the role of neutrophils in antibody therapy in cancer and their regulation by the CD47-SIRPα innate immune checkpoint. Moreover, initial results of CD47-SIRPα blockade in clinical trials are discussed.
PubMed: 35884427
DOI: 10.3390/cancers14143366 -
Journal of Veterinary Internal Medicine 2007Phagocytic activity of neonatal foals has been reported to be similar to that of adult horses, but serum opsonization capacity develops with age and may be further...
BACKGROUND
Phagocytic activity of neonatal foals has been reported to be similar to that of adult horses, but serum opsonization capacity develops with age and may be further altered when opsonins are consumed during infection.
HYPOTHESIS
Phagocytosis, oxidative burst activity, and serum opsonization capacity in neonatal foals admitted to an intensive care unit are reduced in comparison with control foals.
ANIMALS
Blood samples were collected from hospitalized neonatal foals and from control foals. Hospitalized foals were characterized as sick or septic on the basis of a sepsis score and received intravenous plasma transfusion.
METHODS
Phagocytosis, oxidative burst activity, and serum opsonization capacity were tested with flow cytometric analysis. Serum immunoglobulin and complement component 3 concentrations were determined with radial immunodiffusion. Serum amyloid A concentration was assayed with a commercially available solid-phase Sandwich ELISA Kit. Data were analyzed with nonparametric and regression methods. Alpha was set at P = .05.
RESULTS
Phagocytic functions of septic and sick foals were lower than control foals in the initial phase of the study (P = .01). Opsonization capacity was significantly higher when bacteria were opsonized with serum from septic (P = .029) and sick (P = .006) foals than from control foals on day 1. Opsonization capacity in septic foals was comparable with control foals on days 2 and 5. This effect was not accompanied by an increase in serum complement C3 or immunoglobulin G concentrations independently.
CONCLUSIONS AND CLINICAL IMPORTANCE
Our results suggest that phagocytic function could be decreased in hospitalized foals. The synergistic effect of opsonic elements provided by plasma transfusion may sustain opsonization capacity during sepsis.
Topics: Animals; Animals, Newborn; Complement C3; Female; Horse Diseases; Horses; Immunoglobulins; Intensive Care Units; Male; Opsonin Proteins; Phagocytosis; Respiratory Burst; Sepsis; Serum Amyloid A Protein
PubMed: 17708402
DOI: 10.1892/0891-6640(2007)21[797:socpao]2.0.co;2 -
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 -
Mucosal Immunology May 2021Semen is important in determining HIV-1 susceptibility but it is unclear how it affects virus transmission during sexual contact. Mucosal Langerhans cells (LCs) are the...
Semen is important in determining HIV-1 susceptibility but it is unclear how it affects virus transmission during sexual contact. Mucosal Langerhans cells (LCs) are the first immune cells to encounter HIV-1 during sexual contact and have a barrier function as LCs are restrictive to HIV-1. As semen from people living with HIV-1 contains complement-opsonized HIV-1, we investigated the effect of complement on HIV-1 dissemination by human LCs in vitro and ex vivo. Notably, pre-treatment of HIV-1 with semen enhanced LC infection compared to untreated HIV-1 in the ex vivo explant model. Infection of LCs and transmission to target cells by opsonized HIV-1 was efficiently inhibited by blocking complement receptors CR3 and CR4. Complement opsonization of HIV-1 enhanced uptake, fusion, and integration by LCs leading to an increased transmission of HIV-1 to target cells. However, in the absence of both CR3 and CR4, C-type lectin receptor langerin was able to restrict infection of complement-opsonized HIV-1. These data suggest that complement enhances HIV-1 infection of LCs by binding CR3 and CR4, thereby bypassing langerin and changing the restrictive nature of LCs into virus-disseminating cells. Targeting complement factors might be effective in preventing HIV-1 transmission.
Topics: Antibodies, Blocking; Antigens, CD; Cell Line; Complement Activation; Disease Transmission, Infectious; HIV Infections; HIV-1; Host-Parasite Interactions; Humans; Immune Evasion; Integrin alphaXbeta2; Langerhans Cells; Lectins, C-Type; Macrophage-1 Antigen; Mannose-Binding Lectins; Opsonization; Semen
PubMed: 33568786
DOI: 10.1038/s41385-021-00376-9 -
MAbs 2022The increasing global occurrence of recalcitrant multi-drug resistant infections warrants the investigation of alternative therapy options, such as the use of...
The increasing global occurrence of recalcitrant multi-drug resistant infections warrants the investigation of alternative therapy options, such as the use of monoclonal antibodies (mAbs). We used a target-agnostic phage display approach to bacteria lacking bulky, highly variable surface polysaccharides in order to isolate antibodies targeting conserved epitopes among clinically relevant strains. One antibody population contained a high proportion of unique carbohydrate binders, and biolayer interferometry revealed these antibodies bound to lipopolysaccharide (LPS). Antibodies that bound to O1 and O1/O2 LPS were identified. Antibodies were found to promote opsonophagocytic killing by human monocyte-derived macrophages and clearance of macrophage-associated bacteria when assessed using high-content imaging. One antibody, B39, was found to protect mice in a lethal model of pneumonia against both O1 and O2 strains when dosed therapeutically. High-content imaging, western blotting and fluorescence-activated cell sorting were used to determine binding to a collection of clinical O1 and O2 strains. The data suggests B39 binds to D-galactan-I and D-galactan-II of the LPS of O1 and O2 strains. Thus, we have discovered an mAb with novel binding and functional activity properties that is a promising candidate for development as a novel biotherapeutic for the treatment and prevention of infections.
Topics: Animals; Antibodies, Bacterial; Drug Resistance, Multiple, Bacterial; Epitopes; Humans; Klebsiella Infections; Klebsiella pneumoniae; Lipopolysaccharides; Macrophages; Mice; Opsonization
PubMed: 34923908
DOI: 10.1080/19420862.2021.2006123 -
Acta Pharmaceutica Sinica. B Jan 2021AL3810, a molecular dual inhibitor of the vascular endothelial growth factor receptor (VEGFR) and fibroblast growth factor receptor (FGFR), has earned the permission of...
AL3810, a molecular dual inhibitor of the vascular endothelial growth factor receptor (VEGFR) and fibroblast growth factor receptor (FGFR), has earned the permission of phase II clinical trial for tumor treatment by China FDA. As a reversible ATP-competitive inhibitor, AL3810 targets ATP-binding site on intracellular region of VEGFR and FGFR, whereas, AL3810 lacking interplay with extracellular region of receptors rendered deficient blood-brain tumor barrier (BBTB) recognition, poor brain penetration and unsatisfactory anti-glioma efficacy. Integrin v3 overexpressed on capillary endothelial cells of BBTB as well as glioma cells illuminated ligand-modified liposomes for pinpoint spatial delivery into glioma. The widely accepted peptide c(RGDyK)-modified liposome loading AL3810 of multiple dosing caused hypothermia, activated anti-c(RGDyK)-liposome IgG and IgM antibody and pertinent complements C3b and C5b-9, and experienced complement-dependent opsonization. We newly proposed a pentapeptide mn with superb v3-binding affinity and tailored AL3810-loaded mn-modified liposome that afforded impervious blood circulation, targeting ability, and glioma therapeutic expertise as vastly alleviated immune opsonization on the underpinning of the finite antibodies and complements assembly. Stemming from attenuated immunogenicity, peptide mn strengthened liposome functions as a promising nanocarrier platform for molecular targeting agents.
PubMed: 33532193
DOI: 10.1016/j.apsb.2020.07.024 -
International Journal of Nanomedicine 2018It has been proposed that many hypersensitivity reactions to nanopharmaceuticals represent complement (C)-activation-related pseudoallergy (CARPA), and that pigs provide...
Involvement of complement activation in the pulmonary vasoactivity of polystyrene nanoparticles in pigs: unique surface properties underlying alternative pathway activation and instant opsonization.
BACKGROUND
It has been proposed that many hypersensitivity reactions to nanopharmaceuticals represent complement (C)-activation-related pseudoallergy (CARPA), and that pigs provide a sensitive animal model to study the phenomenon. However, a recent study suggested that pulmonary hypertension, the pivotal symptom of porcine CARPA, is not mediated by C in cases of polystyrene nanoparticle (PS-NP)-induced reactions.
GOALS
To characterize PS-NPs and reexamine the contribution of CARPA to their pulmonary reactivity in pigs.
STUDY DESIGN
C activation by 200, 500, and 750 nm (diameter) PS-NPs and their opsonization were measured in human and pig sera, respectively, and correlated with hemodynamic effects of the same NPs in pigs in vivo.
METHODS
Physicochemical characterization of PS-NPs included size, ζ-potential, cryo-transmission electron microscopy, and hydrophobicity analyses. C activation in human serum was measured by ELISA and opsonization of PS-NPs in pig serum by Western blot and flow cytometry. Pulmonary vasoactivity of PS-NPs was quantified in the porcine CARPA model.
RESULTS
PS-NPs are monodisperse, highly hydrophobic spheres with strong negative surface charge. In human serum, they caused size-dependent, significant rises in C3a, Bb, and sC5b-9, but not C4d. Exposure to pig serum led within minutes to deposition of C5b-9 and opsonic iC3b on the NPs, and opsonic iC3b fragments (C3dg, C3d) also appeared in serum. PS-NPs caused major hemodynamic changes in pigs, primarily pulmonary hypertension, on the same time scale (minutes) as iC3b fragmentation and opsonization proceeded. There was significant correlation between C activation by different PS-NPs in human serum and pulmonary hypertension in pigs.
CONCLUSION
PS-NPs have extreme surface properties with no relevance to clinically used nanomedicines. They can activate C via the alternative pathway, entailing instantaneous opsonization of NPs in pig serum. Therefore, rather than being solely C-independent reactivity, the mechanism of PS-NP-induced hypersensitivity in pigs may involve C activation. These data are consistent with the "double-hit" concept of nanoparticle-induced hypersensitivity reactions involving both CARPA and C-independent pseudoallergy.
Topics: Animals; Complement Activation; Complement C3b; Drug Hypersensitivity; Humans; Immunologic Factors; Liposomes; Male; Nanoparticles; Polystyrenes; Pulmonary Circulation; Surface Properties; Swine
PubMed: 30349254
DOI: 10.2147/IJN.S161369 -
FASEB BioAdvances Apr 2019A crucial step in the pathogenesis of periodontal disease (PD) is activation of osteoclasts (OC) by numerous virulence factors produced by (). To understand...
A crucial step in the pathogenesis of periodontal disease (PD) is activation of osteoclasts (OC) by numerous virulence factors produced by (). To understand pathogenesis of periodontal disease and the role of specific adaptive immune responses, effects of antibodies on -induced OC differentiation and function were investigated. Human peripheral blood-derived monocytes were differentiated to osteoclasts in the presence or absence of: a) ; b) antibodies to ; and c) antibody-opsonized . Findings suggest significant induction of osteoclastogenesis by when compared to control cultures, whereas opsonization decreased osteoclastogenesis by 45%. Immune receptor gene expression profile in the presence of opsonized showed marked up-regulation of TLR1 (3-fold) and TLR2 (2-fold) along with FcγRIIB (2-fold) and FcγRIII receptors (5-fold), but not TLR4 and FcRγ receptors. Interestingly, blocking FcγRIIB, but not FcγRIII receptor, reversed the inhibitory effects of opsonized suggesting a critical role played by FcγRIIB in osteoclastogenesis. Furthermore, opsonized transformed OC precursors to a "macrophage phenotype" suggesting a bone protective role of the immune complexes in modulating osteoclastogenesis, probably by competing as an agonist for PRRs, and inducing selective activation of FcγRs with simultaneous suppression of FcRγ which regulates bone resorptive process. Further defining effective antibody isotypes, avidity, and antigenic specificity could improve targets for eliciting protective immunity.
PubMed: 31355360
DOI: 10.1096/fba.2018-00018