Impact of in vitro digestion on gastrointestinal fate and uptake of silver nanoparticles with different surface modifications

Nanomaterials, especially silver nanoparticles (AgNPs), are used in a broad range of products owing to their antimicrobial potential. Oral ingestion is considered as a main exposure route to AgNPs. This study aimed to investigate the impact of the biochemical conditions within the human digestive tract on the intestinal fate of AgNPs across an intestinal in vitro model of differentiated Caco-2/HT29-MTX cells. The co-culture model was exposed to different concentrations (250–2500 µg/L) of pristine and in vitro digested (IVD) AgNPs and silver nitrate for 24 h. ICP-MS and spICP-MS measurements were performed for quantification of total Ag and AgNPs. The AgNPs size distribution, dissolution, and particle concentration (mass- and number-based) were characterized in the cell fraction and in the apical and basolateral compartments of the monolayer cultures. A significant fraction of the AgNPs dissolved (86–92% and 48–70%) during the digestion. Cellular exposure to increasing concentrations of pristine or IVD AgNPs resulted in a concentration dependent increase of total Ag and AgNPs content in the cellular fractions. The cellular concentrations were significantly lower following exposure to IVD AgNPs compared to the pristine AgNPs. Transport of silver as either total Ag or AgNPs was limited (<0.1%) following exposure to pristine and IVD AgNPs. We conclude that the surface chemistry of AgNPs and their digestion influence their dissolution properties, uptake/association with the Caco-2/HT29-MTX monolayer. This highlights the need to take in vitro digestion into account when studying nanoparticle toxicokinetics and toxicodynamics in cellular in vitro model systems.</p

Oxidation as an Additional Mechanism Underlying Reduced Clot Permeability and Impaired Fibrinolysis in Type 2 Diabetes

Aims. We sought to investigate whether enhanced oxidation contributes to unfavorable fibrin clot properties in patients with diabetes. Methods. We assessed plasma fibrin clot permeation ( , a measure of the pore size in fibrin networks) and clot lysis time induced by recombinant tissue plasminogen activator (CLT) in 163 consecutive type 2 diabetic patients (92 men and 71 women) aged 65 ± 8.8 years with a mean glycated hemoglobin (HbA1c) of 6.8%. We also measured oxidative stress markers, including nitrotyrosine, the soluble form of receptor for advanced glycation end products (sRAGE), 8-iso-prostaglandin F 2 (8-iso-PGF 2 ), oxidized low-density lipoprotein (oxLDL), and advanced glycation end products (AGE). Results. There were inverse correlations between and nitrotyrosine, sRAGE, 8-iso-PGF 2 , and oxLDL. CLT showed a positive correlation with oxLDL and nitrotyrosine but not with other oxidation markers. All these associations remained significant for after adjustment for fibrinogen, disease duration, and HbA1c (all &lt; 0.05), while oxLDL was the only independent predictor of CLT. Conclusions. Our study shows that enhanced oxidative stress adversely affects plasma fibrin clot properties in type 2 diabetic patients, regardless of disease duration and glycemia control

Multimarker approach in discriminating patients with symptomatic and asymptomatic atherosclerotic carotid artery stenosis

BACKGROUND AND PURPOSE: Several circulating biomarkers have been implicated in carotid atherosclerotic plaque rupture and thrombosis; however, their clinical utility remains unknown. The aim of this study was to determine the role of a large biomarker panel in the discrimination of symptomatic (S) vs. asymptomatic (A/S) subjects in a contemporary population with carotid artery stenosis (CS). METHODS: Prospective sampling of circulating cytokines and blood lipids was performed in 300 unselected, consecutive patients with ≥50% CS, as assessed by duplex ultrasound (age 47-83 years; 110 with A/S and 190 with S) who were referred for potential CS revascularization. RESULTS: CS severity and pharmacotherapy did not differ between the A/S and S patients. The median values of total cholesterol, low-density lipoprotein cholesterol, and lipoprotein(a) did not differ, but high-density lipoprotein (HDL) cholesterol was significantly higher (p<0.001) and triglycerides were lower (p=0.03) in the A/S-CS group than in the S-CS group. Interleukin-6 (IL-6) and high-sensitivity C-reactive protein were higher (p=0.04 and p=0.07, respectively) in the S-CS group. Circulating visfatin, soluble CD 40 receptor ligand, soluble vascular cell adhesion molecule, leptin, adiponectin, IL-1β, IL-8, IL-18, monocyte chemoattractant protein-1, myeloperoxidase, matrix metalloproteinases-8, -9, and -10, and fibrinogen were similar, but tissue inhibitor of matrix metalloproteinases-1 (TIMP) was reduced in S-CS compared to A/S-CS (p=0.02). Nevertheless, incorporation of TIMP and IL-6 did not improve the HDL-cholesterol receiver operating characteristics for S-CS status prediction. S-CS status was unrelated to angiographic stenosis severity or plaque burden, as assessed by intravascular ultrasound (p=0.16 and p=0.67, respectively). Multivariate logistic regression analysis revealed low HDL-cholesterol to be the only independent predictor of CS symptoms, with an odds ratio of 1.81 (95% confidence interval=1.15-2.84, p=0.01) for HDL <1.00 mmol/L (first quartile) vs. >1.37 (third quartile). In S-CS, osteoprotegerin and lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) were elevated in those with recent vs. remote symptoms (p=0.01 and p=0.02, respectively). CONCLUSIONS: In an all-comer CS population on contemporary pharmacotherapy, low HDL-cholesterol (but not other previously implicated or several novel circulating biomarkers) is an independent predictor of S-CS status. In addition, an increase in circulating osteoprotegerin and Lp-PLA(2) may transiently indicate S transformation of the carotid atherosclerotic plaque

Bioavailability and biodistribution of differently charged polystyrene nanoparticles upon oral exposure in rats

The likelihood of oral exposure to nanoparticles (NPs) is increasing, and it is necessary to evaluate the oral bioavailability of NPs. In vitro approaches could help reducing animal studies, but validation against in vivo studies is essential. Previously, we assessed the translocation of 50 nm polystyrene NPs of different charges (neutral, positive and negative) using a Caco-2/HT29-MTX in vitro intestinal translocation model. The NPs translocated in a surface charge-dependent manner. The present study aimed to validate this in vitro intestinal model by an in vivo study. For this, rats were orally exposed to a single dose of these polystyrene NPs and the uptake in organs was determined. A negatively charged NP was taken up more than other NPs, with the highest amounts in kidney (37.4 µg/g tissue), heart (52.8 µg/g tissue), stomach wall (98.3 µg/g tissue) and small intestinal wall (94.4 µg/g tissue). This partly confirms our in vitro findings, where the same NPs translocated to the highest extent. The estimated bioavailability of different types of NPs ranged from 0.2 to 1.7 % in vivo, which was much lower than in vitro (1.6–12.3 %). Therefore, the integrated in vitro model cannot be used for a direct prediction of the bioavailability of orally administered NPs. However, the model can be used for prioritizing NPs before further in vivo testing for risk assessment. © 2015, The Author(s)