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

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

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

Predicting the Role of DNA Polymerase β Alone or with KRAS Mutations in Advanced NSCLC Patients Receiving Platinum-Based Chemotherapy

: Clinical data suggest that only a subgroup of non-small cell lung cancer (NSCLC) patients has long-term benefits after front-line platinum-based therapy. We prospectively investigate whether KRAS status and DNA polymerase β expression could help identify patients responding to platinum compounds. Prospectively enrolled, advanced NSCLC patients treated with a first-line regimen containing platinum were genotyped for KRAS and centrally evaluated for DNA polymerase β expression. Overall survival (OS), progression-free survival (PFS), and the objective response rate (ORR) were recorded. Patients with KRAS mutations had worse OS (hazard ratio (HR): 1.37, 95% confidence interval (95% CI): 0.70-2.27). Negative DNA polymerase β staining identified a subgroup with worse OS than patients expressing the protein (HR: 1.43, 95% CI: 0.57-3.57). The addition of KRAS to the analyses further worsened the prognosis of patients with negative DNA polymerase β staining (HR: 1.67, 95% CI: 0.52-5.56). DNA polymerase β did not influence PFS and ORR. KRAS may have a negative role in platinum-based therapy responses in NSCLC, but its impact is limited. DNA polymerase β, when not expressed, might indicate a group of patients with poor outcomes. KRAS mutations in tumors not expressing DNA polymerase β further worsens survival. Therefore, these two biomarkers together might well identify patients for whom alternatives to platinum-based chemotherapy should be used

GADD45β loss ablates innate immunosuppression in cancer

T cell exclusion from the tumour microenvironment (TME) is a major barrier to overcoming immune escape. Here we identify a myeloid-intrinsic mechanism governed by the NF-κB effector molecule GADD45β that restricts tumour-associated inflammation and T cell trafficking into tumours. In various models of solid cancers refractory to immunotherapies, including hepatocellular carcinoma (HCC) and ovarian adenocarcinoma, Gadd45b inhibition in myeloid cells restored activation of pro-inflammatory tumour-associated macrophages (TAM) and intratumoural immune infiltration, thereby diminishing oncogenesis. Our results provide a basis to interpret clinical evidence that elevated expression of GADD45B confers poor clinical outcomes in most human cancers. Further, they suggest a therapeutic target in GADD45β for re-programming TAM to overcome immunosuppression and T cell exclusion from the TME

Immunohistochemical Characterization of a Renal Nephroblastoma in a Trp53-mutant and Prolyl Isomerase 1-deficient Mouse

6A nephroblastoma is a tumor arising from metanephric blastema occurring in childhood. Among laboratory rodents, nephroblastoma has been frequently reported in rats, but it remains exceedingly rare in mice. The present work describes a nephroblastoma in a young mouse homozygous for the specific Trp53 R172H point mutation coupled with targeted deletion of the Pin1 gene. The affected kidney was effaced by a biphasic tumor with an epithelial component arranged in tubules surrounded by nests of blastemal cells. Immunohistochemically, the neoplasm was diffusely positive for Wilms' tumor antigen. The epithelial component expressed markers of renal tubular differentiation including wide-spectrum cytokeratin, E-cadherin and folate-binding protein. Furthermore, the neoplasm exhibited a high proliferative index and diffuse nucleocytoplasmic β-catenin expression. Based on histological and immunohistochemical features, a diagnosis of nephroblastoma potentially associated with Trp53 loss and oncogenic β-catenin activation has been proposed.nonenoneVittoria Castiglioni;Marcella De Maglie;Roberta Queliti;Alessandra Rustighi;Giannino Del Sal;Enrico RadaelliVittoria, Castiglioni; Marcella De, Maglie; Roberta, Queliti; Rustighi, Alessandra; DEL SAL, Giannino; Enrico, Radaell

Additional file 4: Figure S3. of Selective proliferative response of microglia to alternative polarization signals

Cellular localization of Ki67 immunostaining in brain astrocytes. Brain sections were analyzed by immunohistochemistry for the expression of Ki67 using antibodies against Ki67 (green labeling) and GFAP (red staining) following the icv administration of 250 ng IL-4. Ki67-positive cells co-localize with GFAP-positive cells (white arrows). Scale bar, 10 Οm. (PDF 105 kb

Additional file 1: Table S1. of Selective proliferative response of microglia to alternative polarization signals

Oligonucleotides used in real time PCR assays. (PDF 182 kb