Characterization of DNA-protein complexes by nanoparticle tracking analysis and their association with systemic lupus erythematosus

Large soluble CD18 complexes with exclusive ICAM-1-binding properties are shed during immune cell migration in inflammation

The family of heterodimeric CD11/CD18 integrins facilitate leukocyte adhesion and migration in a wide range of normal physiologic responses, as well as in the pathology of inflammatory diseases. Soluble CD18 (sCD18) is found mainly in complexes with hydrodynamic radii of 5 and 7.2 nm, suggesting a compositional difference. Earlier work reported that the complexes include at least part of the CD11a or CD11b chains containing the intercellular adhesion molecule (ICAM)-1 binding domain, and that sCD18 is capable of quantitatively competing with the cell membrane-bound form for ICAM-1 binding. However, it is not clear if the size differences between the sCD18 complexes reflect any functional variance regarding shedding from the cell membrane or binding to ICAM-1. Here, we show evidence that sCD18 found in serum regulates release of the proinflammatory cytokine monocyte chemoattractant protein-1 (MCP-1/CCL2) from fibroblast-like synovial cells. Further, only large sCD18 complexes are capable of binding to ICAM-1. Migrating neutrophils shed large, but not small, sCD18 complexes. Together, these observations explain results measured from patients with rheumatoid arthritis (RA), where large sCD18 complexes dominated in local inflammatory processes involving neutrophil influx into zones of inflammation. Our data points to a previously unappreciated aspect of sCD18 integrin biology as regulators of inflammation in the context of migrating leukocyte. Surprisingly, this regulation is tied to sCD18 complex size, opening new opportunities for therapeutic intervention in serious inflammatory diseases such as arthritis.

Mini Review On: The Roles of DNA Nanomaterials in Phototherapy

DNA-based functional nanomaterials are distinguished by their structural designability and functional controllability, making them particularly attractive in the biomedical field. Using DNA nanomaterials for cancer treatment through synergistic approaches combining photodynamic therapy and photothermal therapy has garnered significant attention. This growing interest has driven the active development of various DNA nanomaterials tailored for integrated strategies targeting cancer, including phototherapy, chemotherapy, etc. This review provides an overview of DNA nanoplatforms employed in phototherapy and synergistic therapy for cancer treatment. It highlights recent advances in DNA nanoplatforms that leverage multifaceted synergy to enhance phototherapeutic efficacy. It also offers a new perspectives and clinical application potential of DNA nanomaterials in synergistic phototherapy for malignant tumors, focusing on developments in recent years and potential directions for future research and applications.

DNA-Binding Proteins and Passenger Proteins in Plasma DNA-Protein Complexes: Imprint of Parental Cells or Key Mediators of Carcinogenesis Processes?

Knowledge of the composition of proteins that interact with plasma DNA will provide a better understanding of the homeostasis of circulating nucleic acids and the various modes of interaction with target cells, which may be useful in the development of gene targeted therapy approaches. The goal of the present study is to shed light on the composition and architecture of histone-containing nucleoprotein complexes (NPCs) from the blood plasma of healthy females (HFs) and breast cancer patients (BCPs) and to explore the relationship of proteins with crucial steps of tumor progression: epithelial-mesenchymal transition (EMT), cell proliferation, invasion, cell migration, stimulation of angiogenesis, and immune response. MALDI-TOF mass spectrometric analysis of NPCs isolated from blood samples using affine chromatography was performed. Bioinformatics analysis showed that the shares of DNA-binding proteins in the compositions of NPCs in normal and cancer patients are comparable and amount to 40% and 33%, respectively; in total, we identified 38 types of DNA-binding motifs. Functional enrichment analysis using FunRich 3.13 showed that, in BCP blood, the share of DNA-binding proteins involved in nucleic acid metabolism increased, while the proportion of proteins involved in intercellular communication and signal transduction decreased. The representation of NPC passenger proteins in breast cancer also changes: the proportion of proteins involved in transport increases and the share of proteins involved in energy biological pathways decreases. Moreover, in the HF blood, proteins involved in the processes of apoptosis were more represented in the composition of NPCs and in the BCP blood-in the processes of active secretion. For the first time, bioinformatics approaches were used to visualize the architecture of circulating NPCs in the blood and to show that breast cancer has an increased representation of passenger proteins involved in EMT, cell proliferation, invasion, cell migration, and immune response. Using breast cancer protein data from the Human Protein Atlas (HPA) and DEPC, we found that 86% of NPC proteins in the blood of BCPs were not previously annotated in these databases. The obtained data may indirectly indicate directed protein sorting in NPCs, which, along with extracellular vesicles, can not only be diagnostically significant molecules for liquid biopsy, but can also carry out the directed transfer of genetic material from donor cells to recipient cells.

DNA corona on nanoparticles leads to an enhanced immunostimulatory effect with implications for autoimmune diseases

Autoimmune and inflammatory diseases are highly complex, limiting treatment and the development of new therapies. Recent work has shown that cell-free DNA bound to biological microparticles is linked to systemic lupus erythematosus, a prototypic autoimmune disease. However, the heterogeneity and technical challenges associated with the study of biological particles have hindered a mechanistic understanding of their role. Our goal was to develop a well-controlled DNA-particle model system to understand how DNA-particle complexes affect cells. We first characterized the adsorption of DNA on the surface of polystyrene nanoparticles (200 nm and 2 µm) using transmission electron microscopy, dynamic light scattering, and colorimetric DNA concentration assays. We found that DNA adsorbed on the surface of nanoparticles was resistant to degradation by DNase 1. Macrophage cells incubated with the DNA-nanoparticle complexes had increased production of pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6). We probed two intracellular DNA sensing pathways, toll-like receptor 9 (TLR9) and cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING), to determine how cells sense the DNA-nanoparticle complexes. We found that the cGAS-STING pathway is the primary route for the interaction between DNA-nanoparticles and macrophages. These studies provide a molecular and cellular-level understanding of DNA-nanoparticle-macrophage interactions. In addition, this work provides the mechanistic information necessary for future in vivo experiments to elucidate the role of DNA-particle interactions in autoimmune diseases, providing a unique experimental framework to develop novel therapeutic approaches.

Amyloid-β aggregates activate peripheral monocytes in mild cognitive impairment

The peripheral immune system is important in neurodegenerative diseases, both in protecting and inflaming the brain, but the underlying mechanisms remain elusive. Alzheimer's Disease is commonly preceded by a prodromal period. Here, we report the presence of large Aβ aggregates in plasma from patients with mild cognitive impairment (n = 38). The aggregates are associated with low level Alzheimer's Disease-like brain pathology as observed by 11C-PiB PET and 18F-FTP PET and lowered CD18-rich monocytes. We characterize complement receptor 4 as a strong binder of amyloids and show Aβ aggregates are preferentially phagocytosed and stimulate lysosomal activity through this receptor in stem cell-derived microglia. KIM127 integrin activation in monocytes promotes size selective phagocytosis of Aβ. Hydrodynamic calculations suggest Aβ aggregates associate with vessel walls of the cortical capillaries. In turn, we hypothesize aggregates may provide an adhesion substrate for recruiting CD18-rich monocytes into the cortex. Our results support a role for complement receptor 4 in regulating amyloid homeostasis.

The applications of functional materials-based nano-formulations in the prevention, diagnosis and treatment of chronic inflammation-related diseases

Chronic inflammation, in general, refers to systemic immune abnormalities most often caused by the environment or lifestyle, which is the basis for various skin diseases, autoimmune diseases, cardiovascular diseases, liver diseases, digestive diseases, cancer, and so on. Therapeutic strategies have focused on immunosuppression and anti-inflammation, but conventional approaches have been poor in enhancing the substantive therapeutic effect of drugs. Nanomaterials continue to attract attention for their high flexibility, durability and simplicity of preparation, as well as high profitability. Nanotechnology is used in various areas of clinical medicine, such as medical diagnosis, monitoring and treatment. However, some related problems cannot be ignored, including various cytotoxic and worsening inflammation caused by the nanomaterials themselves. This paper provides an overview of functional nanomaterial formulations for the prevention, diagnosis and treatment of chronic inflammation-related diseases, with the intention of providing some reference for the enhancement and optimization of existing therapeutic approaches.

The extrafollicular response is sufficient to drive initiation of autoimmunity and early disease hallmarks of lupus

Introduction

Many autoimmune diseases are characterized by germinal center (GC)-derived, affinity-matured, class-switched autoantibodies, and strategies to block GC formation and progression are currently being explored clinically. However, extrafollicular responses can also play a role. The aim of this study was to investigate the contribution of the extrafollicular pathway to autoimmune disease development.

Methods

We blocked the GC pathway by knocking out the transcription factor Bcl-6 in GC B cells, leaving the extrafollicular pathway intact. We tested the impact of this intervention in two murine models of systemic lupus erythematosus (SLE): a pharmacological model based on chronic epicutaneous application of the Toll-like receptor (TLR)-7 agonist Resiquimod (R848), and 564Igi autoreactive B cell receptor knock-in mice. The B cell intrinsic effects were further investigated in vitro and in autoreactive mixed bone marrow chimeras.

Results

GC block failed to curb autoimmune progression in the R848 model based on anti-dsDNA and plasma cell output, superoligomeric DNA complexes, and immune complex deposition in glomeruli. The 564Igi model confirmed this based on anti-dsDNA and plasma cell output. In vitro, loss of Bcl-6 prevented GC B cell expansion and accelerated plasma cell differentiation. In a competitive scenario in vivo, B cells harboring the genetic GC block contributed disproportionately to the plasma cell output.

Discussion

We identified the extrafollicular pathway as a key contributor to autoimmune progression. We propose that therapeutic targeting of low quality and poorly controlled extrafollicular responses could be a desirable strategy to curb autoreactivity, as it would leave intact the more stringently controlled and high-quality GC responses providing durable protection against infection.

Immunoassay for detection of oligomeric proteins

The mass concentration of specific proteins is often used as a biomarker and play an important part in diagnostics of inflammatory diseases. Monodisperse proteins are robustly measured in immunoassays, but it is considerably more complicated to measure polydisperse oligomeric proteins. The degree of protein oligomerization is critical for functional aspects. For such proteins, information on both the mass concentration as well as the degree of oligomerization is important. Here, a time-resolved immunofluorometric assay (TRIFMA) with sensitivity for protein structure to detect homo-oligomeric and polydisperse proteins is presented. An established TRIFMA for mannan-binding lectin (MBL) was modified by implementing an additional blocking step prior to coating with capture antibodies, leading to a decrease in coating density. Recombinant human MBL was sorted into small, intermediate, and large complexes, using gel permeation chromatography. Small MBL complexes were poorly detectable by TRIFMA with a sparse antibody coating, while larger complexes produced a strong response. From comparison of molecular dimensions, this difference can be related to the size of oligomers. In conclusion, it is possible to design oligomer-size-sensitive immunoassays by regulating the inter-molecular distance of capture antibodies on a scale comparable to the size of the oligomers.