Iron oxide nanoparticles induce Pseudomonas aeruginosa growth, induce biofilm formation, and inhibit antimicrobial peptide function.

Given the increased use of iron-containing nanoparticles in a number of applications, it is important to understand any effects that iron-containing nanoparticles can have on the environment and human health. Since iron concentrations are extremely low in body fluids, there is potential that iron-containing nanoparticles may influence the ability of bacteria to scavenge iron for growth, affect virulence and inhibit antimicrobial peptide (AMP) function. In this study, Pseudomonas aeruginosa (PA01) and AMPs were exposed to iron oxide nanoparticles, hematite (α-Fe2O3), of different sizes ranging from 2 to 540 nm (2 ± 1, 43 ± 6, 85 ± 25 and 540 ± 90 nm) in diameter. Here we show that the greatest effect on bacterial growth, biofilm formation, and AMP function impairment is found when exposed to the smallest particles. These results are attributed in large part to enhanced dissolution observed for the smallest particles and an increase in the amount of bioavailable iron. Furthermore, AMP function can be additionally impaired by adsorption onto nanoparticle surfaces. In particular, lysozyme readily adsorbs onto the nanoparticle surface which can lead to loss of peptide activity. Thus, this current study shows that co-exposure of nanoparticles and known pathogens can impact host innate immunity. Therefore, it is important that future studies be designed to further understand these types of impacts.

Role of PON in anoxia-reoxygenation injury: a Drosophila melanogaster transgenic model.

BACKGROUND: Paraoxonase 1 (PON1) is a protein found associated with high density lipoprotein (HDL), thought to prevent oxidative modification of low-density lipoprotein (LDL). This enzyme has been implicated in lowering the risk of cardiovascular disease. Anoxia-reoxygenation and oxidative stress are important elements in cardiovascular and cerebrovascular disease. However, the role of PON1 in anoxia-reoxygenation or anoxic injury is unclear. We hypothesize that PON1 prevents anoxia-reoxygenation injury. We set out to determine whether PON1 expression in Drosophila melanogaster protects against anoxia-reoxygenation (A-R) induced injury. METHODS: Wild type (WT) and transgenic PON1 flies were exposed to anoxia (100% Nitrogen) for different time intervals (from 1 to 24 hours). After the anoxic period, flies were placed in room air for reoxygenation. Activity and survival of flies was then recorded. RESULTS: Within 5 minutes of anoxia, all flies fell into a stupor state. After reoxygenation, survivor flies resumed activity with some delay. Interestingly, transgenic flies recovered from stupor later than WT. PON1 transgenic flies had a significant survival advantage after A-R stress compared with WT. The protection conferred by PON1 expression was present regardless of the age or dietary restriction. Furthermore, PON1 expression exclusively in CNS conferred protection. CONCLUSION: Our results support the hypothesis that PON1 has a protective role in anoxia-reoxygenation injury, and its expression in the CNS is sufficient and necessary to provide a 100% survival protection.

TSH regulates pendrin membrane abundance and enhances iodide efflux in thyroid cells.

Thyroid hormones are essential for normal development and metabolism. Their synthesis requires transport of iodide into thyroid follicles. The mechanisms involving the apical efflux of iodide into the follicular lumen are poorly elucidated. The discovery of mutations in the SLC26A4 gene in patients with Pendred syndrome (congenital deafness, goiter, and defective iodide organification) suggested a possible role for the encoded protein, pendrin, as an apical iodide transporter. We determined whether TSH regulates pendrin abundance at the plasma membrane and whether this influences iodide efflux. Results of immunoblot and immunofluorescence experiments reveal that TSH and forskolin rapidly increase pendrin abundance at the plasma membrane through the protein kinase A pathway in PCCL-3 rat thyroid cells. The increase in pendrin membrane abundance correlates with a decrease in intracellular iodide as determined by measuring intracellular (125)iodide and can be inhibited by specific blocking of pendrin. Elimination of the putative protein kinase A phosphorylation site T717A results in a diminished translocation to the membrane in response to forskolin. These results demonstrate that pendrin translocates to the membrane in response to TSH and suggest that it may have a physiological role in apical iodide transport and thyroid hormone synthesis.

Hypoxia increases transepithelial electrical conductance and reduces occludin at the plasma membrane in alveolar epithelial cells via PKC-ζ and PP2A pathway.

During pulmonary edema, the alveolar space is exposed to a hypoxic environment. The integrity of the alveolar epithelial barrier is required for the reabsorption of alveolar fluid. Tight junctions (TJ) maintain the integrity of this barrier. We set out to determine whether hypoxia creates a dysfunctional alveolar epithelial barrier, evidenced by an increase in transepithelial electrical conductance (G(t)), due to a decrease in the abundance of TJ proteins at the plasma membrane. Alveolar epithelial cells (AEC) exposed to mild hypoxia (Po(2) = 50 mmHg) for 30 and 60 min decreased occludin abundance at the plasma membrane and significantly increased G(t). Other cell adhesion molecules such as E-cadherin and claudins were not affected by hypoxia. AEC exposed to hypoxia increased superoxide, but not hydrogen peroxide (H(2)O(2)). Overexpression of superoxide dismutase 1 (SOD1) but not SOD2 prevented the hypoxia-induced G(t) increase and occludin reduction in AEC. Also, overexpression of catalase had a similar effect as SOD1, despite not detecting any increase in H(2)O(2) during hypoxia. Blocking PKC-ζ and protein phosphatase 2A (PP2A) prevented the hypoxia-induced occludin reduction at the plasma membrane and increase in G(t). In summary, we show that superoxide, PKC-ζ, and PP2A are involved in the hypoxia-induced increase in G(t) and occludin reduction at the plasma membrane in AEC.

[Effect of hypocapnia/alkalosis on the fluid filtration rate in isolated and perfused rabbit lungs]. / Efecto de la hipocapnia/alcalosis sobre la tasa de filtración de liquidos en pulmones aislados y perfundidos de conejos.

Hypocapnia/alkalosis is a consequence of several lung and metabolic pathologies. The aim of this study was to determine whether the increase of fluid filtration rate (FFR) that occurs during Hypocapnia/alkalosis circumstances is determined by hypocapnia, alkalosis or both. 7 groups were formed (N=36) using isolated rabbit lungs. Group 1: Control (PCO2 6%, pH: 7.35-7.45); Group 2 (n=6): Hypocapnia/Alkalosis (CO2 1%, pH: 7.9); Group 3 (n=6): Hypocapnia/Normo-pH (CO2 1% pH 7.35-7.45), Group 4 (n=6) Normocapnia/Alcalosis (CO2 6%, pH: 7.9). Fenoterol, papaverine and hydrocortisone were added to Groups 5, 6 and 7 (n=4) respectively, all under Normocapnia/Alkalosis. FFR and Pulmonary Arterial Pressure (Pap) were considerably higher in group 2 than in control (FFR: 1.92g/min +/- 0.6 vs 0.0 g/min +/- 0.006). A strong influence exerted by pH was observed when Group 3 and group 4 were compared (FFR: 0.02 g/min +/- 0.009 vs 2.3 g/min +/- 0.9) and (Pap: 13.5 cmH2O +/- 1.4 vs 90 cmH2O +/- 15). A reduced effect was observed in groups 5 and 6 (papaverine and hydrocorisone) and a totally abolished effect was observed in group 7 (fenoterol) (FFR: 0.001 +/- 0.0003 mL/min and Pap: 14 +/- 0.8 cmH2O). Pulmonary edema induced by Hypocapnia/alkalosis is a consequence of alkalosis and not of hypocapnia. This effect could be due to inflammatory damage in the lung parenchyma and alkalosis-mediated vasoconstriction.

Efecto de la hipocapnia/alcalosis sobre la tasa de filtración de líquidos en pulmones aislados y perfundidos de conejos / Effect of hypocapnia/alkalosis on the fluid filtration rate in isolated and perfused rabbit lungs

La hipocapnia/alcalosis es una situación que se presenta como consecuencia de diversas patologías pulmonares o metabólicas. El objetivo de este estudio fue determinar si el aumento de la tasa de filtración de liquido (TFL) que ocurre bajo estas circunstancias, está determinado por la hipocapnia, la alcalosis o la suma de ambas. Se realizaron 7 grupos (n=36), utilizando pulmones aislados de conejos. Grupo 1: Control (PCO2 6 por ciento, pH: 7,35-7,45); Grupo 2 (n=6): Hipocapnia/Alcalosis (CO2 1 por ciento, pH: 7,9); Grupo 3 (n=6): Hipocapnia/Normo-pH (CO2 1 por ciento pH 7,35-7,45), Grupo 4 (n=6) Normocapnia/Alcalosis (CO2 6 por ciento, pH: 7,9). En los grupos 5, 6 y 7 (n=4), todos bajo condición de Normocapnia/Alcalosis se añadió fenoterol, papaverina, e hidrocortisona respectivamente. La TFL y la presión de arteria pulmonar (Pap) fueron considerablemente mayores en el grupo 2 que en el control (TFL:1,92g/min ± 0,6 vs 0,0g/min ± 0,006), observándose una marcada influencia del pH, al comparar el grupo 3 y el grupo 4 (TFL: 0,02g/min ± 0,009 vs 2,3g/min ± 0,9) y (Pap: 13,5 cmH2O ± 1,4 vs 90 cmH2O ± 15). Se observó una disminución del efecto en los grupos 5 y 6 (papaverina e hidrocortisona) y su abolición total con fenoterol (grupo 7) (TFL: 0,001 ± 0,0003 g/min y Pap: 14 ± 0,8 cmH2O). El edema pulmonar inducido por Hipocapnia/Alcalosis es consecuencia principalmente de la alcalosis y no de la hipocapnia. Dicho efecto podría ser debido a un daño inflamatorio a nivel del parénquima y a la vasoconstricción causada por la alcalosis.