-
Neural Regeneration Research Jun 2024Spinal cord injury remains a major cause of disability in young adults, and beyond acute decompression and rehabilitation, there are no pharmacological treatments to...
Spinal cord injury remains a major cause of disability in young adults, and beyond acute decompression and rehabilitation, there are no pharmacological treatments to limit the progression of injury and optimize recovery in this population. Following the thorough investigation of the complement system in triggering and propagating cerebral neuroinflammation, a similar role for complement in spinal neuroinflammation is a focus of ongoing research. In this work, we survey the current literature investigating the role of complement in spinal cord injury including the sources of complement proteins, triggers of complement activation, and role of effector functions in the pathology. We study relevant data demonstrating the different triggers of complement activation after spinal cord injury including direct binding to cellular debris, and or activation via antibody binding to damage-associated molecular patterns. Several effector functions of complement have been implicated in spinal cord injury, and we critically evaluate recent studies on the dual role of complement anaphylatoxins in spinal cord injury while emphasizing the lack of pathophysiological understanding of the role of opsonins in spinal cord injury. Following this pathophysiological review, we systematically review the different translational approaches used in preclinical models of spinal cord injury and discuss the challenges for future translation into human subjects. This review emphasizes the need for future studies to dissect the roles of different complement pathways in the pathology of spinal cord injury, to evaluate the phases of involvement of opsonins and anaphylatoxins, and to study the role of complement in white matter degeneration and regeneration using translational strategies to supplement genetic models.
PubMed: 38845224
DOI: 10.4103/NRR.NRR-D-24-00116 -
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 -
BioRxiv : the Preprint Server For... May 2024Granzymes are a family of serine proteases mainly expressed by CD8 T cells, natural killer cells, and innate-like lymphocytes. Although their major role is thought to be...
Granzymes are a family of serine proteases mainly expressed by CD8 T cells, natural killer cells, and innate-like lymphocytes. Although their major role is thought to be the induction of cell death in virally infected and tumor cells, accumulating evidence suggests some granzymes can regulate inflammation by acting on extracellular substrates. Recently, we found that the majority of tissue CD8 T cells in rheumatoid arthritis (RA) synovium, inflammatory bowel disease and other inflamed organs express granzyme K (GZMK), a tryptase-like protease with poorly defined function. Here, we show that GZMK can activate the complement cascade by cleaving C2 and C4. The nascent C4b and C2a fragments form a C3 convertase that cleaves C3, allowing further assembly of a C5 convertase that cleaves C5. The resulting convertases trigger every major event in the complement cascade, generating the anaphylatoxins C3a and C5a, the opsonins C4b and C3b, and the membrane attack complex. In RA synovium, GZMK is enriched in areas with abundant complement activation, and fibroblasts are the major producers of complement C2, C3, and C4 that serve as targets for GZMK-mediated complement activation. Our findings describe a previously unidentified pathway of complement activation that is entirely driven by lymphocyte-derived GZMK and proceeds independently of the classical, lectin, or alternative pathways. Given the widespread abundance of -expressing T cells in tissues in chronic inflammatory diseases and infection, GZMK-mediated complement activation is likely to be an important contributor to tissue inflammation in multiple disease contexts.
PubMed: 38826230
DOI: 10.1101/2024.05.22.595315 -
Frontiers in Immunology 2024The California purple sea urchin, , relies solely on an innate immune system to combat the many pathogens in the marine environment. One aspect of their molecular...
INTRODUCTION
The California purple sea urchin, , relies solely on an innate immune system to combat the many pathogens in the marine environment. One aspect of their molecular defenses is the () gene family that is upregulated in response to immune challenge. The gene sequences are highly variable both within and among animals and likely encode thousands of SpTrf isoforms within the sea urchin population. The native SpTrf proteins bind foreign targets and augment phagocytosis of a marine . A recombinant (r)SpTrf-E1-Ec protein produced by also binds but does not augment phagocytosis.
METHODS
To address the question of whether other rSpTrf isoforms function as opsonins and augment phagocytosis, six rSpTrf proteins were expressed in insect cells.
RESULTS
The rSpTrf proteins are larger than expected, are glycosylated, and one dimerized irreversibly. Each rSpTrf protein cross-linked to inert magnetic beads (rSpTrf::beads) results in different levels of surface binding and phagocytosis by phagocytes. Initial analysis shows that significantly more rSpTrf::beads associate with cells compared to control BSA::beads. Binding specificity was verified by pre-incubating the rSpTrf::beads with antibodies, which reduces the association with phagocytes. The different rSpTrf::beads show significant differences for cell surface binding and phagocytosis by phagocytes. Furthermore, there are differences among the three distinct types of phagocytes that show specific vs. constitutive binding and phagocytosis.
CONCLUSION
These findings illustrate the complexity and effectiveness of the sea urchin innate immune system driven by the natSpTrf proteins and the phagocyte cell populations that act to neutralize a wide range of foreign pathogens.
Topics: Animals; Phagocytosis; Phagocytes; Recombinant Proteins; Protein Binding; Strongylocentrotus purpuratus; Immunity, Innate; Protein Isoforms; Sea Urchins; Vibrio; Opsonin Proteins
PubMed: 38742116
DOI: 10.3389/fimmu.2024.1372904 -
International Journal of Pharmaceutics May 2024Cationic liposomes specifically target monocytes in blood, rendering them promising drug-delivery tools for cancer immunotherapy, vaccines, and therapies for monocytic...
Cationic liposomes specifically target monocytes in blood, rendering them promising drug-delivery tools for cancer immunotherapy, vaccines, and therapies for monocytic leukaemia. The mechanism behind this monocyte targeting ability is, however, not understood, but may involve plasma proteins adsorbed on the liposomal surfaces. To shed light on this, we investigated the biomolecular corona of three different types of PEGylated cationic liposomes, finding all of them to adsorb hyaluronan-associated proteins and proteoglycans upon incubation in human blood plasma. This prompted us to study the role of the TLR4 co-receptors CD44 and CD14, both involved in signalling and uptake pathways of proteoglycans and glycosaminoglycans. We found that separate inhibition of each of these receptors hampered the monocyte uptake of the liposomes in whole human blood. Based on clues from the biomolecular corona, we have thus identified two receptors involved in the targeting and uptake of cationic liposomes in monocytes, in turn suggesting that certain proteoglycans and glycosaminoglycans may serve as monocyte-targeting opsonins. This mechanistic knowledge may pave the way for rational design of future monocyte-targeting drug-delivery platforms.
Topics: Liposomes; Humans; Monocytes; Polyethylene Glycols; Cations; Hyaluronan Receptors; Lipopolysaccharide Receptors; Protein Corona; Toll-Like Receptor 4; Proteoglycans; Drug Delivery Systems
PubMed: 38621615
DOI: 10.1016/j.ijpharm.2024.124129 -
Small (Weinheim An Der Bergstrasse,... Mar 2024Engineering of catalytically active inorganic nanomaterials holds promising prospects for biomedicine. Catalytically active metal oxides show applications in enhancing...
Engineering of catalytically active inorganic nanomaterials holds promising prospects for biomedicine. Catalytically active metal oxides show applications in enhancing wound healing but have also been employed to induce cell death in photodynamic or radiation therapy. Upon introduction into a biological system, nanomaterials are exposed to complex fluids, causing interaction and adsorption of ions and proteins. While protein corona formation on nanomaterials is acknowledged, its modulation of nanomaterial catalytic efficacy is less understood. In this study, proteomic analyses and nano-analytic methodologies quantify and characterize adsorbed proteins, correlating this protein layer with metal oxide catalytic activity in vitro and in vivo. The protein corona comprises up to 280 different proteins, constituting up to 38% by weight. Enhanced complement factors and other opsonins on nanocatalyst surfaces lead to their uptake into macrophages when applied topically, localizing >99% of the nanomaterials in tissue-resident macrophages. Initially, the formation of the protein corona significantly reduces the nanocatalysts' activity, but this activity can be partially recovered in endosomal conditions due to the proteolytic degradation of the corona. Overall, the research reveals the complex relationship between physisorbed proteins and the catalytic characteristics of specific metal oxide nanoparticles, providing design parameters for optimizing nanocatalysts in complex biological environments.
PubMed: 38556634
DOI: 10.1002/smll.202311115 -
Cells Mar 2024Disulfiram (DSF), an anti-alcoholism medicine, exerts treatment effects in patients suffering from persistent Borreliosis and also exhibits anti-cancer effects through...
Disulfiram (DSF), an anti-alcoholism medicine, exerts treatment effects in patients suffering from persistent Borreliosis and also exhibits anti-cancer effects through its copper chelating derivatives and induction of oxidative stress in mitochondria. Since chronic/persistent borreliosis is characterized by increased amounts of pro-inflammatory macrophages, this study investigated opsonin-independent phagocytosis, migration, and surface marker expression of in vivo activated and in vitro cultured human monocyte-derived phagocytes (macrophages and dendritic cells) with and without DSF treatment. Phagocytosis of non-opsonized Dynabeads M-450 and migration of macrophages and dendritic cells were monitored using live cell analyzer Juli™ Br for 24 h, imaging every 3.5 min. To simultaneously monitor phagocyte function, results were analyzed by a newly developed software based on the differential phase contrast images of cells before and after ingestion of Dynabeads. DSF decreased the phagocytic capacities exhibited by in vitro enriched and long-lived phagocytes. Although no chemotactic gradient was applied to the test system, vigorous spontaneous migration was observed. We therefore set up an algorithm to monitor and quantify both phagocytosis and migration simultaneously. DSF not only reduced phagocytosis in a majority of these long-lived phagocytes but also impaired their migration. Despite these selective effects by DSF, we found that DSF reduced the expression densities of surface antigens CD45 and CD14 in all of our long-lived phagocytes. In cells with a high metabolic activity and high mitochondrial contents, DSF led to cell death corresponding to mitochondrial oxidative stress, whereas metabolically inactive phagocytes survived our DSF treatment protocol. In conclusion, DSF affects the viability of metabolically active phagocytes by inducing mitochondrial stress and secondly attenuates phagocytosis and migration in some long-lived phagocytes.
Topics: Humans; Disulfiram; Opsonin Proteins; Phagocytosis; Phagocytes; Macrophages
PubMed: 38534379
DOI: 10.3390/cells13060535 -
ImmunoHorizons Mar 2024Bacillus anthracis peptidoglycan (PGN) is a major component of the bacterial cell wall and a key pathogen-associated molecular pattern contributing to anthrax pathology,...
Bacillus anthracis peptidoglycan (PGN) is a major component of the bacterial cell wall and a key pathogen-associated molecular pattern contributing to anthrax pathology, including organ dysfunction and coagulopathy. Increases in apoptotic leukocytes are a late-stage feature of anthrax and sepsis, suggesting there is a defect in apoptotic clearance. In this study, we tested the hypothesis that B. anthracis PGN inhibits the capacity of human monocyte-derived macrophages (MΦ) to efferocytose apoptotic cells. Exposure of CD163+CD206+ MΦ to PGN for 24 h impaired efferocytosis in a manner dependent on human serum opsonins but independent of complement component C3. PGN treatment reduced cell surface expression of the proefferocytic signaling receptors MERTK, TYRO3, AXL, integrin αVβ5, CD36, and TIM-3, whereas TIM-1, αVβ3, CD300b, CD300f, STABILIN-1, and STABILIN-2 were unaffected. ADAM17 is a major membrane-bound protease implicated in mediating efferocytotic receptor cleavage. We found multiple ADAM17-mediated substrates increased in PGN-treated supernatant, suggesting involvement of membrane-bound proteases. ADAM17 inhibitors TAPI-0 and Marimastat prevented TNF release, indicating effective protease inhibition, and modestly increased cell-surface levels of MerTK and TIM-3 but only partially restored efferocytic capacity by PGN-treated MΦ. We conclude that human serum factors are required for optimal recognition of PGN by human MΦ and that B. anthracis PGN inhibits efferocytosis in part by reducing cell surface expression of MERTK and TIM-3.
Topics: Humans; c-Mer Tyrosine Kinase; Bacillus anthracis; Peptidoglycan; Anthrax; Efferocytosis; Hepatitis A Virus Cellular Receptor 2; Macrophages; Cell Wall
PubMed: 38517345
DOI: 10.4049/immunohorizons.2300109 -
PeerJ 2024Mammalian models, such as murine, are used widely in pathophysiological studies because they have a high degree of similarity in body temperature, metabolism, and immune...
Mammalian models, such as murine, are used widely in pathophysiological studies because they have a high degree of similarity in body temperature, metabolism, and immune response with humans. However, non-vertebrate animal models have emerged as alternative models to study the host-pathogen interaction with minimal ethical concerns. is an alternative model that has proved useful in studying the interaction of the host with either bacteria or fungi, performing drug testing, and assessing the immunological response to different microorganisms. The immune response includes cellular and humoral components with structural and functional similarities to the immune effectors found in higher vertebrates, such as humans. An important humoral effector stimulated during infections is apolipophorin III (apoLp-III), an opsonin characterized by its lipid and carbohydrate-binding properties that participate in lipid transport, as well as immunomodulatory activity. Despite some parameters, such as the measurement of phenoloxidase activity, melanin production, hemocytes counting, and expression of antimicrobial peptides genes are already used to assess the immune response to pathogens with different virulence degrees, the apoLp-III quantification remains to be a parameter to assess the immune response in this invertebrate. Here, we propose an immunological tool based on an enzyme-linked immunosorbent assay that allows apoLp-III quantification in the hemolymph of larvae challenged with pathogenic agents. We tested the system with hemolymph coming from larvae infected with , , , , and . The results revealed significantly higher concentrations of apoLp-III when each microbial species was inoculated, in comparison with untouched larvae, or inoculated with phosphate-buffered saline. We also demonstrated that the apoLp-III levels correlated with the strains' virulence, which was already reported. To our knowledge, this is one of the first attempts to quantify apoLp-III, using a quick and easy-to-use serological technique.
Topics: Humans; Animals; Mice; Moths; Apolipoproteins; Larva; Host-Pathogen Interactions; Mammals
PubMed: 38500532
DOI: 10.7717/peerj.17117