Biomarkers of nanomaterials hazard from multi-layer data.

There is an urgent need to apply effective, data-driven approaches to reliably predict engineered nanomaterial (ENM) toxicity. Here we introduce a predictive computational framework based on the molecular and phenotypic effects of a large panel of ENMs across multiple in vitro and in vivo models. Our methodology allows for the grouping of ENMs based on multi-omics approaches combined with robust toxicity tests.

Uncoupled biological and chronological aging of neutrophils in cancer promotes tumor progression.

Background: Beyond their fundamental role in homeostasis and host defense, neutrophilic granulocytes (neutrophils) are increasingly recognized to contribute to the pathogenesis of malignant tumors. Recently, aging of mature neutrophils in the systemic circulation has been identified to be critical for these immune cells to properly unfold their homeostatic and anti-infectious functional properties. The role of neutrophil aging in cancer remains largely obscure.

uPA-PAI-1 heteromerization promotes breast cancer progression by attracting tumorigenic neutrophils.

High intratumoral levels of urokinase-type plasminogen activator (uPA)-plasminogen activator inhibitor-1 (PAI-1) heteromers predict impaired survival and treatment response in early breast cancer. The pathogenetic role of this protein complex remains obscure. Here, we demonstrate that heteromerization of uPA and PAI-1 multiplies the potential of the single proteins to attract pro-tumorigenic neutrophils.

Vitronectin stabilizes intravascular adhesion of neutrophils by coordinating β2 integrin clustering.

The recruitment of neutrophils from the microvasculature to the site of injury or infection represents a key event in the inflammatory response. Vitronectin (VN) is a multifunctional macromolecule abundantly present in blood and extracellular matrix. The role of this glycoprotein in the extravasation process of circulating neutrophils remains elusive.

Neutrophils promote venular thrombosis by shaping the rheological environment for platelet aggregation.

In advanced inflammatory disease, microvascular thrombosis leads to the interruption of blood supply and provokes ischemic tissue injury. Recently, intravascularly adherent leukocytes have been reported to shape the blood flow in their immediate vascular environment. Whether these rheological effects are relevant for microvascular thrombogenesis remains elusive.

Plasminogen Activator Inhibitor-1 Promotes Neutrophil Infiltration and Tissue Injury on Ischemia-Reperfusion.

Objective: Ischemia-reperfusion (I/R) injury significantly contributes to organ dysfunction and failure after myocardial infarction, stroke, and transplantation. In addition to its established role in the fibrinolytic system, plasminogen activator inhibitor-1 has recently been implicated in the pathogenesis of I/R injury. The underlying mechanisms remain largely obscure.

The surface chemistry determines the spatio-temporal interaction dynamics of quantum dots in atherosclerotic lesions.

Aim: To optimize the design of nanoparticles for diagnosis or therapy of vascular diseases, it is mandatory to characterize the determinants of nano-bio interactions in vascular lesions.

Materials & Methods: Using ex vivo and in vivo microscopy, we analyzed the interactive behavior of quantum dots with different surface functionalizations in atherosclerotic lesions of ApoE-deficient mice.

Results: We demonstrate that quantum dots with different surface functionalizations exhibit specific interactive behaviors with distinct molecular and cellular components of the injured vessel wall.

Early pulmonary response is critical for extra-pulmonary carbon nanoparticle mediated effects: comparison of inhalation versus intra-arterial infusion exposures in mice.

Background: The death toll associated with inhaled ambient particulate matter (PM) is attributed mainly to cardio-vascular rather than pulmonary effects. However, it is unclear whether the key event for cardiovascular impairment is particle translocation from lung to circulation (direct effect) or indirect effects due to pulmonary particle-cell interactions. In this work, we addressed this issue by exposing healthy mice via inhalation and intra-arterial infusion (IAI) to carbon nanoparticles (CNP) as surrogate for soot, a major constituent of (ultrafine) urban PM.

Dexamethasone-conjugated DNA nanotubes as anti-inflammatory agents in vivo.

The biopolymer DNA allows to create nanoscale, biocompatible structures, which can be designed in a target-specific and stimuli-responsive manner. DNA carrier systems with these characteristics hold a great potential for nanomedical applications, such as for the treatment of inflammatory diseases. Here we used a DNA-based drug carrier system for the pH-dependent delivery of the glucocorticoid dexamethasone into macrophages, a cell type with a key role in the regulation of inflammation.

The Endothelial Glycocalyx Controls Interactions of Quantum Dots with the Endothelium and Their Translocation across the Blood-Tissue Border.

Advances in the engineering of nanoparticles (NPs), which represent particles of less than 100 nm in one external dimension, led to an increasing utilization of nanomaterials for biomedical purposes. A prerequisite for their use in diagnostic and therapeutic applications, however, is the targeted delivery to the site of injury. Interactions between blood-borne NPs and the vascular endothelium represent a critical step for nanoparticle delivery into diseased tissue.

The glycocalyx regulates the uptake of nanoparticles by human endothelial cells in vitro.

Aim: To assess the role of the endothelial glycocalyx (eGCX) for the uptake of nanoparticles by endothelial cells.

Methods: The expression of the eGCX on cultured human umbilical vein endothelial cells was determined by immunostaining of heparan sulfate. Enzymatic degradation of the eGCX was achieved by incubating the cells with eGCX-shedding enzymes.

Aged neutrophils contribute to the first line of defense in the acute inflammatory response.

Under steady-state conditions, aged neutrophils are removed from the circulation in bone marrow, liver, and spleen, thereby maintaining myeloid cell homeostasis. The fate of these aged immune cells under inflammatory conditions, however, remains largely obscure. Here, we demonstrate that in the acute inflammatory response during endotoxemia, aged neutrophils cease returning to the bone marrow and instead rapidly migrate to the site of inflammation.

Platelets Guide Leukocytes to Their Sites of Extravasation.

Effective immune responses require the directed migration of leukocytes from the vasculature to the site of injury or infection. How immune cells "find" their site of extravasation remains largely obscure. Here, we identified a previously unrecognized role of platelets as pathfinders guiding leukocytes to their exit points in the microvasculature: upon onset of inflammation, circulating platelets were found to immediately adhere at distinct sites in venular microvessels enabling these cellular blood components to capture neutrophils and, in turn, inflammatory monocytes via CD40-CD40L-dependent interactions.

Multiphoton Microscopy of Nonfluorescent Nanoparticles In Vitro and In Vivo.

Nanotechnology holds great promise for a plethora of potential applications. The interaction of engineered nanomaterials with living cells, tissues, and organisms is, however, only partly understood. Microscopic investigations of nano-bio interactions are mostly performed with a few model nanoparticles (NPs) which are easy to visualize, such as fluorescent quantum dots.

Influence of Surface Modifications on the Spatiotemporal Microdistribution of Quantum Dots In Vivo.

For biomedical applications of nanoconstructs, it is a general prerequisite to efficiently reach the desired target site. In this regard, it is crucial to determine the spatiotemporal distribution of nanomaterials at the microscopic tissue level. Therefore, the effect of different surface modifications on the distribution of microinjected quantum dots (QDs) in mouse skeletal muscle tissue has been investigated.

Intercellular Transport of Nanomaterials is Mediated by Membrane Nanotubes In Vivo.

So-called membrane nanotubes are cellular protrusions between cells whose functions include cell communication, environmental sampling, and protein transfer. It has been previously reported that systemically administered carboxyl-modified quantum dots (cQDs) are rapidly taken up by perivascular macrophages in skeletal muscle of healthy mice. Expanding these studies, it is found, by means of in vivo fluorescence microscopy on the mouse cremaster muscle, rapid uptake of cQDs not only by perivascular macrophages but also by tissue-resident cells, which are localized more than 100 μm distant from the closest vessel.

DNA nanotubes as intracellular delivery vehicles in vivo.

DNA-based nanoconstructs possess great potential for biomedical applications. However, the in vivo behavior of such constructs at the microscopic tissue/cell level as well as their inflammatory potential is largely unknown. Unmethylated CpG sequences of DNA are recognized by Toll-like receptor 9 (TLR9), and thus initiate an innate immune response.

Spatiotemporal expression dynamics of selectins govern the sequential extravasation of neutrophils and monocytes in the acute inflammatory response.

Objective: Leukocyte recruitment to the site of inflammation is a key event in a variety of cardiovascular pathologies. Infiltrating neutrophils constitute the first line of defense that precedes a second wave of emigrating monocytes reinforcing the inflammatory reaction. The mechanisms initiating this sequential process remained largely obscure.

Proinflammatory and cytotoxic response to nanoparticles in precision-cut lung slices.

Precision-cut lung slices (PCLS) are an established ex vivo alternative to in vivo experiments in pharmacotoxicology. The aim of this study was to evaluate the potential of PCLS as a tool in nanotoxicology studies. Silver (Ag-NPs) and zinc oxide (ZnO-NPs) nanoparticles as well as quartz particles were used because these materials have been previously shown in several in vitro and in vivo studies to induce a dose-dependent cytotoxic and inflammatory response.

Effects of acute systemic administration of TiO2, ZnO, SiO2, and Ag nanoparticles on hemodynamics, hemostasis and leukocyte recruitment.

It has been suggested that engineered nanomaterials (ENM), once arrived in the circulation, may affect the cardiovascular system. The aim of this in vivo study was to screen major cardiovascular effects of acute systemic administration of a panel of five nanomaterials, TiO2 anatase (NM-101), TiO2 rutile (NM-104), ZnO (NM-110), SiO2 (NM-200) and Ag (NM-300). Mice were anesthetized and the ENM were injected at a dose of 1 mg/kg via a catheter placed in the left femoral artery.

Components of the plasminogen activation system promote engraftment of porous polyethylene biomaterial via common and distinct effects.

Rapid fibrovascularization is a prerequisite for successful biomaterial engraftment. In addition to their well-known roles in fibrinolysis, urokinase-type plasminogen activator (uPA) and tissue plasminogen activator (tPA) or their inhibitor plasminogen activator inhibitor-1 (PAI-1) have recently been implicated as individual mediators in non-fibrinolytic processes, including cell adhesion, migration, and proliferation. Since these events are critical for fibrovascularization of biomaterial, we hypothesized that the components of the plasminogen activation system contribute to biomaterial engraftment.

Synchronized renal tubular cell death involves ferroptosis.

Receptor-interacting protein kinase 3 (RIPK3)-mediated necroptosis is thought to be the pathophysiologically predominant pathway that leads to regulated necrosis of parenchymal cells in ischemia-reperfusion injury (IRI), and loss of either Fas-associated protein with death domain (FADD) or caspase-8 is known to sensitize tissues to undergo spontaneous necroptosis. Here, we demonstrate that renal tubules do not undergo sensitization to necroptosis upon genetic ablation of either FADD or caspase-8 and that the RIPK1 inhibitor necrostatin-1 (Nec-1) does not protect freshly isolated tubules from hypoxic injury. In contrast, iron-dependent ferroptosis directly causes synchronized necrosis of renal tubules, as demonstrated by intravital microscopy in models of IRI and oxalate crystal-induced acute kidney injury.

PVP-coated, negatively charged silver nanoparticles: A multi-center study of their physicochemical characteristics, cell culture and in vivo experiments.

PVP-capped silver nanoparticles with a diameter of the metallic core of 70 nm, a hydrodynamic diameter of 120 nm and a zeta potential of -20 mV were prepared and investigated with regard to their biological activity. This review summarizes the physicochemical properties (dissolution, protein adsorption, dispersability) of these nanoparticles and the cellular consequences of the exposure of a broad range of biological test systems to this defined type of silver nanoparticles. Silver nanoparticles dissolve in water in the presence of oxygen.

Tissue plasminogen activator promotes postischemic neutrophil recruitment via its proteolytic and nonproteolytic properties.

Objective: Neutrophil infiltration of the postischemic tissue considerably contributes to organ dysfunction on ischemia/reperfusion injury. Beyond its established role in fibrinolysis, tissue-type plasminogen activator (tPA) has recently been implicated in nonfibrinolytic processes. The role of this serine protease in the recruitment process of neutrophils remains largely obscure.

Carbon-based nanomaterials accelerate arteriolar thrombus formation in the murine microcirculation independently of their shape.

Although carbon-based nanomaterials (CBNs) have been shown to exert prothrombotic effects in microvessels, it is poorly understood whether CBNs also have the potential to interfere with the process of leukocyte-endothelial cell interactions and whether the shape of CBNs plays a role in these processes. Thus, the aim of this study was to compare the acute effects of two differently shaped CBNs, fiber-shaped single-walled carbon nanotubes (SWCNT) and spherical ultrafine carbon black (CB), on thrombus formation as well as on leukocyte-endothelial cell interactions and leukocyte transmigration in the murine microcirculation upon systemic administration in vivo. Systemic administration of both SWCNT and CB accelerated arteriolar thrombus formation at a dose of 1 mg kg(-1) body weight, whereas SWCNT exerted a prothrombotic effect also at a lower dose (0.