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PloS One 2024We investigated the interactions of unopsonized and opsonized Mycoplasma mycoides subsp. mycoides (Mmm) with bovine macrophages in vitro. Mmm survived and proliferated...
We investigated the interactions of unopsonized and opsonized Mycoplasma mycoides subsp. mycoides (Mmm) with bovine macrophages in vitro. Mmm survived and proliferated extracellularly on bovine macrophage cell layers in the absence of Mmm-specific antisera. Bovine complement used at non-bactericidal concentrations did neither have opsonizing effect nor promoted intracellular survival, whereas Mmm-specific antisera substantially increased phagocytosis and Mmm killing. A phagocytosis-independent uptake of Mmm by macrophages occurred at a high multiplicity of infection, also found to induce the production of TNF, and both responses were unaffected by non-bactericidal doses of bovine complement. Bovine complement used at higher doses killed Mmm in cell-free cultures and completely abrogated TNF responses by macrophages. These results provide a framework to identify Mmm antigens involved in interactions with macrophages and targeted by potentially protective antibodies and point towards a pivotal role of complement in the control of inflammatory responses in contagious bovine pleuropneumonia.
Topics: Animals; Cattle; Macrophages; Phagocytosis; Complement System Proteins; Mycoplasma; Tumor Necrosis Factor-alpha; Pleuropneumonia, Contagious; Mycoplasma mycoides
PubMed: 38935768
DOI: 10.1371/journal.pone.0305851 -
Biomolecules Jun 2024This work describes a novel route for phospholipid fatty acid remodeling involving the monounsaturated fatty acid palmitoleic acid. When administered to human monocytes,...
This work describes a novel route for phospholipid fatty acid remodeling involving the monounsaturated fatty acid palmitoleic acid. When administered to human monocytes, palmitoleic acid rapidly incorporates into membrane phospholipids, notably into phosphatidylcholine (PC). In resting cells, palmitoleic acid remains within the phospholipid pools where it was initially incorporated, showing no further movement. However, stimulation of the human monocytes with either receptor-directed (opsonized zymosan) or soluble (calcium ionophore A23187) agonists results in the rapid transfer of palmitoleic acid moieties from PC to phosphatidylinositol (PI). This is due to the activation of a coenzyme A-dependent remodeling route involving two different phospholipase A enzymes that act on different substrates to generate free palmitoleic acid and lysoPI acceptors. The stimulated enrichment of specific PI molecular species with palmitoleic acid unveils a hitherto-unrecognized pathway for lipid turnover in human monocytes which may play a role in regulating lipid signaling during innate immune activation.
Topics: Humans; Monocytes; Fatty Acids, Monounsaturated; Phosphatidylcholines; Phosphatidylinositols
PubMed: 38927110
DOI: 10.3390/biom14060707 -
Current Oncology (Toronto, Ont.) Jun 2024Neuroblastoma is a pediatric cancer with significant clinical heterogeneity. Despite extensive efforts, it is still difficult to cure children with high-risk... (Review)
Review
Neuroblastoma is a pediatric cancer with significant clinical heterogeneity. Despite extensive efforts, it is still difficult to cure children with high-risk neuroblastoma. Immunotherapy is a promising approach to treat children with this devastating disease. We have previously reported that macrophages are important effector cells in high-risk neuroblastoma. In this perspective article, we discuss the potential function of the macrophage inhibitory receptor SIRPA in the homeostasis of tumor-associated macrophages in high-risk neuroblastoma. The ligand of SIRPA is CD47, known as a "don't eat me" signal, which is highly expressed on cancer cells compared to normal cells. CD47 is expressed on both tumor and stroma cells, whereas SIRPA expression is restricted to macrophages in high-risk neuroblastoma tissues. Notably, high expression is associated with better disease outcome. According to the current paradigm, the interaction between CD47 on tumor cells and SIRPA on macrophages leads to the inhibition of tumor phagocytosis. However, data from recent clinical trials have called into question the use of anti-CD47 antibodies for the treatment of adult and pediatric cancers. The restricted expression of SIRPA on macrophages in many tissues argues for targeting SIRPA on macrophages rather than CD47 in CD47/SIRPA blockade therapy. Based on the data available to date, we propose that disruption of the CD47-SIRPA interaction by anti-CD47 antibody would shift the macrophage polarization status from M1 to M2, which is inferred from the 1998 study by Timms et al. In contrast, the anti-SIRPA F(ab') lacking Fc binds to SIRPA on the macrophage, mimics the CD47-SIRPA interaction, and thus maintains M1 polarization. Anti-SIRPA F(ab') also prevents the binding of CD47 to SIRPA, thereby blocking the "don't eat me" signal. The addition of tumor-opsonizing and macrophage-activating antibodies is expected to enhance active tumor phagocytosis.
Topics: CD47 Antigen; Humans; Neuroblastoma; Receptors, Immunologic; Antigens, Differentiation; Macrophages
PubMed: 38920727
DOI: 10.3390/curroncol31060243 -
Frontiers in Immunology 2024Extracellular vesicles (EVs), characterized by low immunogenicity, high biocompatibility and targeting specificity along with excellent blood-brain barrier permeability,... (Review)
Review
Extracellular vesicles (EVs), characterized by low immunogenicity, high biocompatibility and targeting specificity along with excellent blood-brain barrier permeability, are increasingly recognized as promising drug delivery vehicles for treating a variety of diseases, such as cancer, inflammation and viral infection. However, recent findings demonstrate that the intracellular delivery efficiency of EVs fall short of expectations due to phagocytic clearance mediated by the host mononuclear phagocyte system through Fcγ receptors, complement receptors as well as non-opsonic phagocytic receptors. In this text, we investigate a range of bacterial virulence proteins that antagonize host phagocytic machinery, aiming to explore their potential in engineering EVs to counteract phagocytosis. Special emphasis is placed on IdeS secreted by and ImpA secreted by , as they not only counteract phagocytosis but also bind to highly upregulated surface biomarkers αβ on cancer cells or cleave the tumor growth and metastasis-promoting factor CD44, respectively. This suggests that bacterial anti-phagocytic proteins, after decorated onto EVs using pre-loading or post-loading strategies, can not only improve EV-based drug delivery efficiency by evading host phagocytosis and thus achieve better therapeutic outcomes but also further enable an innovative synergistic EV-based cancer therapy approach by integrating both phagocytosis antagonism and cancer targeting or deactivation.
Topics: Extracellular Vesicles; Phagocytosis; Humans; Animals; Bacterial Proteins; Neoplasms; Integrin alphaVbeta3; Hyaluronan Receptors; Pseudomonas aeruginosa
PubMed: 38903499
DOI: 10.3389/fimmu.2024.1418061 -
Vaccine Jun 2024Subunit vaccines require an immunostimulant (adjuvant) and/or delivery system to induce immunity. However, currently, available adjuvants are either too dangerous in...
Subunit vaccines require an immunostimulant (adjuvant) and/or delivery system to induce immunity. However, currently, available adjuvants are either too dangerous in terms of side effects for human use (experimental adjuvants) or have limited efficacy and applicability. In this study, we examined the capacity of mannose-lipopeptide ligands to enhance the immunogenicity of a vaccine consisting of polyleucine(L)-antigen conjugates anchored to liposomes. The clinically tested Group A Streptococcus (GAS) B-cell epitope, J8, combined with universal T helper PADRE (P) was used as the antigen. Six distinct mannose ligands were incorporated into neutral liposomes carrying LPJ8. While induced antibody titers were relatively low, the ligand carrying mannose, glycine/lysine spacer, and two palmitic acids as liposomal membrane anchoring moieties (ligand 3), induced significantly higher IgG titers than non-mannosylated liposomes. The IgG titers were significantly enhanced when positively charged liposomes were employed. Importantly, the produced antibodies were able to kill GAS bacteria. Unexpectedly, the physical mixture of only ligand 3 and PJ8 produced self-assembled nanorods that induced antibody titers as high as those elicited by the lead liposomal formulation and antigen adjuvanted with the potent, but toxic, complete Freund's adjuvant (CFA). Antibodies produced upon immunization with PJ8 + 3 were even more opsonic than those induced by CFA + PJ8. Importantly, in contrast to CFA, ligand 3 did not induce observable adverse reactions or excessive inflammatory responses. Thus, we demonstrated that a mannose ligand, alone, can serve as an effective vaccine nanoadjuvant.
PubMed: 38897890
DOI: 10.1016/j.vaccine.2024.06.027 -
Science Advances Jun 2024Immunotoxicity remains a major hindrance to chemotherapy in cancer therapy. Nanocarriers may alleviate the immunotoxicity, but the optimal design remains unclear. Here,...
Immunotoxicity remains a major hindrance to chemotherapy in cancer therapy. Nanocarriers may alleviate the immunotoxicity, but the optimal design remains unclear. Here, we created two variants of maytansine (DM1)-loaded synthetic high-density lipoproteins (D-sHDL) with either physically entrapped (D-sHDL) or chemically conjugated (D-sHDL) DM1. We found that D-sHDL showed less accumulation in the tumor draining lymph nodes (DLNs) and femur, resulting in a lower toxicity against myeloid cells than D-sHDL via avoiding scavenger receptor class B type 1 (SR-B1)-mediated DM1 transportation into the granulocyte-monocyte progenitors and dendritic cells. Therefore, higher densities of lymphocytes in the tumors, DLNs, and blood were recorded in mice receiving D-sHDL, leading to a better efficacy and immune memory of D-sHDL against colon cancer. Furthermore, liposomes with conjugated DM1 (D-Lipo) showed lower immunotoxicity than those with entrapped drug (D-Lipo) through the same mechanism after apolipoprotein opsonization. Our findings highlight the critical role of drug loading patterns in dictating the biological fate and activity of nanomedicine.
Topics: Animals; Nanoparticles; Mice; Cell Line, Tumor; Humans; Scavenger Receptors, Class B; Antineoplastic Agents; Lipoproteins, HDL; Drug Carriers; Colonic Neoplasms; Liposomes; Lipids
PubMed: 38838152
DOI: 10.1126/sciadv.adk9996 -
Frontiers in Immunology 2024Innate immunity is crucial to reducing parasite burden and contributing to survival in severe malaria. Monocytes are key actors in the innate response and, like...
INTRODUCTION
Innate immunity is crucial to reducing parasite burden and contributing to survival in severe malaria. Monocytes are key actors in the innate response and, like macrophages, are plastic cells whose function and phenotype are regulated by the signals from the microenvironment. In the context of cerebral malaria (CM), monocyte response constitutes an important issue to understand. We previously demonstrated that decreased percentages of nonclassical monocytes were associated with death outcomes in CM children. In the current study, we postulated that monocyte phagocytosis function is impacted by the severity of malaria infection.
METHODS
To study this hypothesis, we compared the opsonic and nonopsonic phagocytosis capacity of circulant monocytes from Beninese children with uncomplicated malaria (UM) and CM. For the CM group, samples were obtained at inclusion (D0) and 3 and 30 days after treatment (D3, D30). The phagocytosis capacity of monocytes and their subsets was characterized by flow cytometry and transcriptional profiling by studying genes known for their functional implication in infected-red blood cell (iRBC) elimination or immune escape.
RESULTS
Our results confirm our hypothesis and highlight the higher capacity of nonclassical monocytes to phagocyte iRBC. We also confirm that a low number of nonclassical monocytes is associated with CM outcome when compared to UM, suggesting a mobilization of this subpopulation to the cerebral inflammatory site. Finally, our results suggest the implication of the inhibitory receptors LILRB1, LILRB2, and Tim3 in phagocytosis control.
DISCUSSION
Taken together, these data provide a better understanding of the interplay between monocytes and malaria infection in the pathogenicity of CM.
Topics: Humans; Malaria, Cerebral; Phagocytosis; Monocytes; Male; Child, Preschool; Female; Child; Infant; Plasmodium falciparum; Opsonin Proteins; Erythrocytes; Immunity, Innate
PubMed: 38835780
DOI: 10.3389/fimmu.2024.1358853 -
Journal of Leukocyte Biology Jun 2024
PubMed: 38829387
DOI: 10.1093/jleuko/qiae119 -
ACS Infectious Diseases Jun 2024is a fungus classified by the World Health Organization as a critically important pathogen, which poses a significant threat to immunocompromised individuals. In this...
is a fungus classified by the World Health Organization as a critically important pathogen, which poses a significant threat to immunocompromised individuals. In this study, we present the chemical synthesis and evaluation of two semisynthetic vaccine candidates targeting the capsular polysaccharide glucuronoxylomannan (GXM) of . These semisynthetic glycoconjugate vaccines contain an identical synthetic decasaccharide (M2 motif) antigen. This antigen is present in serotype A strains, which constitute 95% of the clinical cryptococcosis cases. This synthetic oligosaccharide was conjugated to two proteins (CRM197 and Anthrax 63 kDa PA) and tested for immunogenicity in mice. The conjugates elicited a specific antibody response that bound to the M2 motif but also exhibited additional cross-reactivity toward M1 and M4 GXM motifs. Both glycoconjugates produced antibodies that bound to GXM in ELISA assays and to live fungal cells. Mice immunized with the CRM197 glycoconjugate produced weakly opsonic antibodies and displayed trends toward increased median survival relative to mice given a mock PBS injection (18 vs 15 days, = 0.06). These findings indicate promise, achieving a successful vaccine demands further optimization of the glycoconjugate. This antigen could serve as a component in a multivalent GXM motif vaccine.
Topics: Cryptococcus neoformans; Animals; Fungal Vaccines; Mice; Cryptococcosis; Glycoconjugates; Vaccines, Conjugate; Antibodies, Fungal; Female; Polysaccharides; Mice, Inbred BALB C; Bacterial Proteins; Antigens, Fungal
PubMed: 38819951
DOI: 10.1021/acsinfecdis.4c00094 -
Frontiers in Bioscience (Landmark... May 2024Recent studies highlighted the presence of anti-α-Gal antibodies in patients implanted with commercial bioprosthetic heart valves (BHVs). BHVs expose residual α-Gal...
BACKGROUND
Recent studies highlighted the presence of anti-α-Gal antibodies in patients implanted with commercial bioprosthetic heart valves (BHVs). BHVs expose residual α-Gal xenoantigen and their recognition by the circulating anti-Gal antibodies leads to opsonization of the device's tissue component with the consequent triggering of a deterioration pathway that culminates with calcification. Small animal models such as mice and rats have been broadly involved in the testing of biomaterials by subcutaneous implantation, especially for the effectiveness of BHVs anti-calcific treatments. However, since models employed for this purpose express α-Gal antigen, the implantation of BHVs' leaflets does not elicit a proper immunological response, so the calcification propensity may be dramatically underestimated.
METHODS
An α-Gal knockout (KO) mouse model has been created, using the CRISP/Cas9 approach, and adopted to assess the calcification potential of commercial BHVs leaflets through the surgical implantation in the back subcutis area. Calcium quantification was performed by inductively coupled plasma analysis; immune response against the BHVs leaflets and α-Gal silencing was evaluated through immunological assays.
RESULTS
Two months after the implantation of commercial BHV leaflets, the anti-Gal antibody titers in KO mice doubled when compared with those found in wild-type (WT) ones. Leaflets explanted from KO mice, after one month, showed a four-time increased calcium deposition concerning the ones explanted from WT. The degree of silencing of α-Gal varied, depending on the specific organ that was assessed. In any case, the animal model was suitable for evaluating implanted tissue responses.
CONCLUSIONS
Such mouse model proved to be an accurate tool for the study of the calcific propensity of commercial BHVs leaflets than those hitherto used. Given its reliability, it could also be successfully used to study even other diseases in which the possible involvement of α-Gal has been observed.
Topics: Animals; Heart Valve Prosthesis; Calcinosis; Mice, Knockout; Bioprosthesis; Mice; Disease Models, Animal; Mice, Inbred C57BL; Male
PubMed: 38812319
DOI: 10.31083/j.fbl2905181