Publications

Ex vivo-loaded white blood cells (WBC) can transfer cargo to pathological foci in the central nervous system (CNS). Here we tested affinity ligand driven in vivo loading of WBC in order to bypass the need for ex vivo WBC manipulation. We used a mouse model of acute brain inflammation caused by local injection of tumor necrosis factor alpha (TNF-α). We intravenously injected nanoparticles targeted to intercellular adhesion molecule 1 (anti-ICAM/NP). We found that (A) at 2 h, >20% of anti-ICAM/NP were localized to the lungs; (B) of the anti-ICAM/NP in the lungs >90% were associated with leukocytes; (C) at 6 and 22 h, anti-ICAM/NP pulmonary uptake decreased; (D) anti-ICAM/NP uptake in brain increased up to 5-fold in this time interval, concomitantly with migration of WBCs into the injured brain. Intravital microscopy confirmed transport of anti-ICAM/NP beyond the blood-brain barrier and flow cytometry demonstrated complete association of NP with WBC in the brain (98%). Dexamethasone-loaded anti-ICAM/liposomes abrogated brain edema in this model and promoted anti-inflammatory M2 polarization of macrophages in the brain. In vivo targeted loading of WBC in the intravascular pool may provide advantages of coopting WBC predisposed to natural rapid mobilization from the lungs to the brain, connected directly via conduit vessels.

JTD Keywords: drug delivery, icam-1, inflammation, lung injury, messenger-rna, migration, model, nanoparticles, neutrophils, pharmacokinetics, t-cells, white bloodcells, Adhesion molecules, Brain, Drug delivery, Inflammation, Nanoparticles, Pharmacokinetics, White blood cells

Goel and colleagues show that CDK4/6 inhibition induces global chromatin changes mediated by AP-1 factors, which mediate key biological and clinical effects in breast cancer. Pharmacologic inhibitors of cyclin-dependent kinases 4 and 6 (CDK4/6) were designed to induce cancer cell cycle arrest. Recent studies have suggested that these agents also exert other effects, influencing cancer cell immunogenicity, apoptotic responses and differentiation. Using cell-based and mouse models of breast cancer together with clinical specimens, we show that CDK4/6 inhibitors induce remodeling of cancer cell chromatin characterized by widespread enhancer activation, and that this explains many of these effects. The newly activated enhancers include classical super-enhancers that drive luminal differentiation and apoptotic evasion, as well as a set of enhancers overlying endogenous retroviral elements that are enriched for proximity to interferon-driven genes. Mechanistically, CDK4/6 inhibition increases the level of several activator protein-1 transcription factor proteins, which are in turn implicated in the activity of many of the new enhancers. Our findings offer insights into CDK4/6 pathway biology and should inform the future development of CDK4/6 inhibitors.

JTD Keywords: Abemaciclib, Androgen receptor, Animal experiment, Animal model, Animal tissue, Apoptosis, Article, Breast cancer, C-jun, Cancer cell, Carcinoembryonic antigen related cell adhesion molecule 1, Caspase 3, Cell cycle arrest, Cells, Chromatin, Chromatin immunoprecipitation, Controlled study, Cyclin dependent kinase 4, Cyclin dependent kinase 6, Dna damage, Epidermal growth factor receptor 2, Estrogen receptor, Female, Flow cytometry, Fulvestrant, Hla drb1 antigen, Human, Human cell, Immunoblotting, Immunogenicity, Immunoprecipitation, Interferon, Luciferase assay, Mcf-7 cell line, Mda-mb-231 cell line, Microarray analysis, Morphogenesis, Mouse, Nonhuman, Palbociclib, Protein, Protein expression, Rb, Resistance, Rna polymerase ii, Rna sequence, Selective-inhibition, Senescence, Short tandem repeat, Signal transduction, Tamoxifen, Transcription elongation, Transcription factor, Transcription factor ap 1, Transcriptome, Tumor biopsy, Tumor differentiation, Tumor spheroid, Tumor xenograft, Vinculin, Whole exome sequencing

Integrins are cell membrane adhesion receptors involved in morphogenesis, immunity, tissue healing, and metastasis. A central, yet unresolved question regarding the function of integrins is how these receptors regulate both their conformation and dynamic nanoscale organization on the membrane to generate adhesion-competent microclusters upon ligand binding. Here we exploit the high spatial (nanometer) accuracy and temporal resolution of single-dye tracking to dissect the relationship between conformational state, lateral mobility, and microclustering of the integrin receptor lymphocyte function-associated antigen 1 (LFA-1) expressed on immune cells. We recently showed that in quiescent monocytes, LFA-1 preorganizes in nanoclusters proximal to nanoscale raft components. We now show that these nanoclusters are primarily mobile on the cell surface with a small (ca. 5%) subset of conformational- active LFA-1 nanoclusters preanchored to the cytoskeleton. Lateral mobility resulted crucial for the formation of microclusters upon ligand binding and for stable adhesion under shear flow. Activation of high-affinity LFA-1 by extracellular Ca 2+ resulted in an eightfold increase on the percentage of immobile nanoclusters and cytoskeleton anchorage. Although having the ability to bind to their ligands, these active nanoclusters failed to support firm adhesion in static and low shear-flow conditions because mobility and clustering capacity were highly compromised. Altogether, our work demonstrates an intricate coupling between conformation and lateral diffusion of LFA-1 and further underscores the crucial role of mobility for the onset of LFA-1 mediated leukocyte adhesion.

JTD Keywords: Cumulative probability distribution, Integrin lymphocyte function-associated antigen 1, Intercellular adhesion molecule, Single molecule detection

Topographic micro and nanostructures can play an interesting role in cell behaviour when cells are cultured on these kinds of patterned substrates. It is especially relevant to investigate the influence of the nanometric dimensions topographic features on cell morphology, proliferation, migration and differentiation. To this end, some of the most recent fabrication technologies, developed for the microelectronics industry, can be used to produce well-defined micro and nanopatterns on biocompatible polymer substrates. In this work, osteoblast-like cells are grown on poly(methyl methacrylate) substrates patterned by nanoimprint lithography techniques. Examination of the cell-substrate interface can reveal important details about the cell morphology and the distribution of the focal contacts on the substrate surface. For this purpose, a combination of focused ion beam milling and scanning electron microscopy techniques has been used to image the cell-substrate interface. This technique, if applied to samples prepared by freeze-drying methods, allows high-resolution imaging of cross-sections through the cell and the substrate, where the interactions between the nanopatterned substrate, the cell and the extracellular matrix, which are normally hidden by the bulk of the cell, can be studied.

JTD Keywords: Electron microscopy, Interface, Nanotopography, Osteoblast, Adhesion molecule, Cell morphology