Role of the mononuclear phagocyte system in the uptake and accumulation of nanoparticles designed for biomedical applications

The unique physical-chemical properties of Nanoparticles (NPs) make them suitable for many biomedical applications (drug delivery, imaging, cell tacking) (Yildirimer et al, 2011). However the design of nanoparticle-based platforms for nanomedicine is extremely challenging and must overcome a number of physiologically constraints, including the Mononuclear Phagocyte System (MPS) (Dawidczyk et al, 2014). The aim of this study was to assess the role of MPS in the biodistribution and accumulation of metallic NPs [iron-oxide NPS and silver NPs (AgNPs)] after single intravenous administration in mice. 24 hours after the treatment mice were sacrificed and underwent complete necropsy. Liver, kidney, spleen and lung were collected, stained with hematoxylin and eosin (HE), Perls stain (for iron-oxide NPs) or autometallography (for AgNPs), and evaluated under a light microscope. Immunostaining for Iba-1 (pan macrophage marker) was applied to localize the NPs aggregates within MPS cells. Histologically, in all treated mice, intracytoplasmic brown granular material (consistent with iron or silver pigment, as confirmed by Perls iron stain and autometallography) was found in stained sections of the liver (within Kupffer cells), spleen (MPS of marginal zone and red pulp) and lung (MPS within alveolar septa). Iron/silver deposits were mainly found in the cytoplasm of MPS cells (Iba1 immunostaining), indicating that most of injected particles were removed from blood circulation by phagocytic cells. These findings indicate that MPS greatly influence NPs biodistribution. For this reason, strategies able to increase bioavailability of NPs by minimizing MPS-mediated clearance are needed. Moreover the potential toxic effects due to the persistence of NPs in MPS should be further investigated

Models of Corporate Criminal Liability in Comparative Law

This Article considers modern systems of criminal justice and the different models of assessing responsibility for crimes committed to benefit corporate interests. The analysis is two-pronged. First, this piece examines systems that have adopted the principle of corporate criminal liability. Within this category, a further important distinction must be made between the most evolved models, which have accepted a requirement of corporate culpability, and those models that reject the idea of an organizational mens rea, imposing instead various corporate liabilities without any separate measure of corporate blameworthiness. Second, this piece considers those models that reject the principle of corporate criminal liability and are restricted to the use of extra-criminal mechanisms for the regulation of corporate crime

Selective proliferative response of microglia to alternative polarization signals

Background: Microglia are resident myeloid cells of the central nervous system (CNS) that are maintained by self-renewal and actively participate in tissue homeostasis and immune defense. Under the influence of endogenous or pathological signals, microglia undertake biochemical transformations that are schematically classified as the pro-inflammatory M1 phenotype and the alternatively activated M2 state. Dysregulated proliferation of M1-activated microglia has detrimental effects, while an increased number of microglia with the alternative, pro-resolving phenotype might be beneficial in brain pathologies; however, the proliferative response of microglia to M2 signals is not yet known. We thus evaluated the ability of interleukin-4 (IL-4), a typical M2 and proliferative signal for peripheral macrophages, to induce microglia proliferation and compared it with other proliferative and M2 polarizing stimuli for macrophages, namely colony-stimulating factor-1 (CSF-1) and the estrogen hormone, 17β-estradiol (E2).Methods: Recombinant IL-4 was delivered to the brain of adult mice by intracerebroventricular (i.c.v.) injection; whole brain areas or ex vivo-sorted microglia were analyzed by real-time PCR for assessing the mRNA levels of genes related with cell proliferation (Ki67, CDK-1, and CcnB2) and M2 polarization (Arg1, Fizz1, Ym-1) or by FACS analyses of in vivo BrdU incorporation in microglia. Primary cultures of microglia and astrocytes were also tested for proliferative effects.Results: Our results show that IL-4 only slightly modified the expression of cell cycle-related genes in some brain areas but not in microglia, where it strongly enhanced M2 gene expression; on the contrary, brain delivery of CSF-1 triggered proliferation as well as M2 polarization of microglia both in vivo and in vitro. Similar to IL-4, the systemic E2 administration failed to induce microglia proliferation while it increased M2 gene expression.Conclusions: Our data show that, in contrast to the wider responsiveness of peripheral macrophages, microglia proliferation is stimulated by selected M2 polarizing stimuli suggesting a role for the local microenvironment and developmental origin of tissue macrophages in regulating self-renewal following alternative activating stimuli

Dose and batch-dependent hepatobiliary toxicity of 10 nm silver nanoparticles

Silver nanoparticles (AgNPs) are widely used because of their antimicrobial properties in medical devices and in a variety of consumer products. The extensive use of AgNPs raises concerns about their potential toxicity, although it is still difficult to draw definite conclusions about their toxicity based on published data. Our preliminary studies performed to compare the effect of the AgNPs size (10-40-100 nm) on toxicity, demonstrated that the smallest AgNPs determine the most severe toxicological effects. In order to best investigate the impact of physicochemical characteristics of 10 nm AgNPs on toxicity, we compare three different batches of 10 nm AgNPs slightly different in size distribution (Batch A: 8.8±1.7 nm; Batch B: 9.4±1.7 nm; Batch C: 10.0±1.8 nm). Mice were intravenously treated with two doses (5 and 10 mg/kg) of the 3 AgNPs. 24 hours after the treatment, mice were euthanized and underwent complete necropsy. Tissues were collected for histopathological examination and total silver content was determined in tissues by inductively coupled plasma mass spectrometry (ICP-MS). All batches induced severe hepatobiliary lesions, i.e. marked hepatocellular necrosis and massive hemorrhage of the gall bladder. The toxicity was dose-dependent and interestingly, the toxic effects were more severe in mice treated with batches A and B that contained smaller AgNPs. Since the total silver mass concentration was similar, the observed batch-dependent toxicity suggest that even subtle differences in size may contribute to relevant changes in the toxicological outcomes, confirming the fundamental involvement of physicochemical features with respect to toxicity

The role of trpa1 in skin physiology and pathology

The transient receptor potential ankyrin 1 (TRPA1), a member of the TRP superfamily of channels, acts as ‘polymodal cellular sensor’ on primary sensory neurons where it mediates the peripheral and central processing of pain, itch, and thermal sensation. However, the TRPA1 expression extends far beyond the sensory nerves. In recent years, much attention has been paid to its expression and function in non-neuronal cell types including skin cells, such as keratinocytes, melanocytes, mast cells, dendritic cells, and endothelial cells. TRPA1 seems critically involved in a series of physiological skin functions, including formation and maintenance of physico-chemical skin barriers, skin cells, and tissue growth and differentiation. TRPA1 appears to be implicated in mechanistic processes in various immunological inflammatory diseases and cancers of the skin, such as atopic and allergic contact dermatitis, psoriasis, bullous pemphigoid, cutaneous T-cell lymphoma, and melanoma. Here, we report recent findings on the implication of TRPA1 in skin physiology and pathophysiology. The potential use of TRPA1 antagonists in the treatment of inflammatory and immunological skin disorders will be also addressed

The Three-Dimensional Signal Collection Field for Fiber Photometry in Brain Tissue

Fiber photometry is used to monitor signals from fluorescent indicators in genetically-defined neural populations in behaving animals. Recently, fiber photometry has rapidly expanded and it now provides researchers with increasingly powerful means to record neural dynamics and neuromodulatory action. However, it is not clear how to select the optimal fiber optic given the constraints and goals of a particular experiment. Here, using combined confocal/2-photon microscope, we quantitatively characterize the fluorescence collection properties of various optical fibers in brain tissue. We show that the fiber size plays a major role in defining the volume of the optically sampled brain region, whereas numerical aperture impacts the total amount of collected signal and, marginally, the shape and size of the collection volume. We show that ~80% of the effective signal arises from 105 to 106 μm3 volume extending ~200 μm from the fiber facet for 200 μm core optical fibers. Together with analytical and ray tracing collection maps, our results reveal the light collection properties of different optical fibers in brain tissue, allowing for an accurate selection of the fibers for photometry and helping for a more precise interpretation of measurements in terms of sampled volume

Tissue distribution and acute toxicity of silver after single intravenous administration in mice: nano-specific and size-dependent effects

Background: Silver nanoparticles (AgNPs) are an important class of nanomaterials used as antimicrobial agents for a wide range of medical and industrial applications. However toxicity of AgNPs and impact of their physicochemical characteristics in in vivo models still need to be comprehensively characterized. The aim of this study was to investigate the effect of size and coating on tissue distribution and toxicity of AgNPs after intravenous administration in mice, and compare the results with those obtained after silver acetate administration. Methods: Male CD-1(ICR) mice were intravenously injected with AgNPs of different sizes (10 nm, 40 nm, 100 nm), citrate-or polyvinylpyrrolidone-coated, at a single dose of 10 mg/kg bw. An equivalent dose of silver ions was administered as silver acetate. Mice were euthanized 24 h after the treatment, and silver quantification by ICP-MS and histopathology were performed on spleen, liver, lungs, kidneys, brain, and blood. Results: For all particle sizes, regardless of their coating, the highest silver concentrations were found in the spleen and liver, followed by lung, kidney, and brain. Silver concentrations were significantly higher in the spleen, lung, kidney, brain, and blood of mice treated with 10 nm AgNPs than those treated with larger particles. Relevant toxic effects (midzonal hepatocellular necrosis, gall bladder hemorrhage) were found in mice treated with 10 nm AgNPs, while in mice treated with 40 nm and 100 nm AgNPs lesions were milder or negligible, respectively. In mice treated with silver acetate, silver concentrations were significantly lower in the spleen and lung, and higher in the kidney than in mice treated with 10 nm AgNPs, and a different target organ of toxicity was identified (kidney). Conclusions: Administration of the smallest (10 nm) nanoparticles resulted in enhanced silver tissue distribution and overt hepatobiliary toxicity compared to larger ones (40 and 100 nm), while coating had no relevant impact. Distinct patterns of tissue distribution and toxicity were observed after silver acetate administration. It is concluded that if AgNPs become systemically available, they behave differently from ionic silver, exerting distinct and size-dependent effects, strictly related to the nanoparticulate form

Effect of mild hypercapnia on outcome and histological injury in a porcine post cardiac arrest model

Aim of the study: To evaluate in an established porcine post cardiac arrest model the effect of a mild hypercapnic ventilatory strategy on outcome. Methods: The left anterior descending coronary artery was occluded in 14 pigs and ventricular fibrillation induced and left untreated for 12 min. Cardiopulmonary resuscitation was performed for 5 min prior to defibrillation. After resuscitation, pigs were assigned to either normocapnic (end-tidal carbon dioxide (EtCO2) target: 35-40 mmHg) or hypercapnic ventilation (EtCO2 45-50 mmHg). Hemodynamics was invasively measured and EtCO2 was monitored with an infrared capnometer. Blood gas analysis, serum neuron-specific enolase (NSE) and high sensitive cardiac troponin T (hs-cTnT) were assessed. Survival and functional recovery were evaluated up to 96 h. Results: Twelve pigs were successfully resuscitated and eight survived up to 96 h, with animals in the hypercapnic group showing trend towards a longer survival. EtCO2 and arterial partial pressure of CO2 were higher in the hypercapnic group compared to the normocapnic one (p <0.01), during the 4-hour intervention. Hypercapnia was associated with higher mean arterial pressure compared to normocapnia (p <0.05). No significant differences were observed in hs-cTnT and in NSE between groups, although the values tended to be lower in the hypercapnic one. Neuronal degeneration was lesser in the frontal cortex of hypercapnic animals compared to the normocapnic ones (p <0.05). Neurological recovery was equivalent in the two groups. Conclusion: Mild hypercapnia after resuscitation was associated with better arterial pressure and lesser neuronal degeneration in this model. Nevertheless, no corresponding improvements in neurological recovery were observed.Peer reviewe