Effect of PEGylation of N-WASP181-200 on the Inhibitory Potency for Renal Aminoglycoside Accumulation

Suppression of P-glycoprotein by cigarette smoke extract in human lung-derived A549/P-gp cells

Effect of long-term treatment with cigarette smoke extract (CSE) on the function and expression of P-glycoprotein (P-gp) in lung alveolar epithelial cells was examined using A549/P-gp cell line expressing P-gp. CSE treatment suppressed P-gp activity in a concentration- and treatment time-dependent manner. The suppression of P-gp activity by CSE was irreversible for at least 96 h after removal of CSE. In addition, CSE treatment suppressed the expression of P-gp mRNA and protein. In order to understand the mechanisms underlying P-gp suppression by CSE, the role of reactive oxygen species (ROS) was examined. CSE treatment increased intracellular ROS level, and suppressed catalase activity. α-Tocopherol suppressed ROS production by CSE, and ameliorated the suppression of P-gp activity by CSE, suggesting that ROS is involved in CSE-induced suppression of P-gp. The role of intracellular signaling pathways such as the nuclear factor κB and mitogen-activated protein kinase pathways was also examined. Among these pathways, the involvement of extracellular signal-regulated kinase (ERK) pathway was suggested. Taken together, long-term CSE treatment may suppress P-gp via modulation of ROS level and ERK pathway in alveolar epithelial cells.

Effect of cigarette smoke extract on P-glycoprotein function in primary cultured and newly developed alveolar epithelial cells

The effect of cigarette smoke extract (CSE) on P-glycoprotein (P-gp) function in the distal lung is unclear. In this study, we first examined the expression and function of P-gp and the effect of CSE in rat primary cultured alveolar epithelial cells. The expression of P-gp protein was observed in type I-like cells, but not in type II cells. In type I-like cells, rhodamine 123 (Rho123) accumulation was enhanced by various P-gp inhibitors such as verapamil and cyclosporine A. In addition, the expression of P-gp mRNAs, mdr1a and mdr1b, as well as P-gp activity increased along with the transdifferentiation. When type I-like cells were co-incubated with CSE, P-gp activity was suppressed. Next, we attempted to clarify the effect of CSE on P-gp function in human-derived cultured alveolar epithelial cells. For this purpose, we isolated an A549 clone (A549/P-gp) expressing P-gp, because P-gp expression in native A549 cells was negligible. In A549/P-gp cells, P-gp was functionally expressed, and the inhibitory effect of CSE on P-gp was observed. These results suggested that smoking would directly suppress P-gp activity, and that A549/P-gp cell line should be a useful model to further study the effect of xenobiotics on P-gp function in the alveolar epithelial cells.

Functional Expression of PEPT2 in the Human Distal Lung Epithelial Cell Line NCl-H441

PURPOSE

The peptide transporter PEPT2 is expressed in alveolar type II epithelial cells. So far, however, no appropriate alveolar epithelial cell line for studying PEPT2 function has been known. In this study, we examined the functional expression of PEPT2 in the human distal lung epithelial cell line NCl-H441 (H441).

METHODS

Expression of PEPT2 mRNA and protein was examined in H441 cells. Transport function of PEPT2 was studied using glycylsarcosine (Gly-Sar) as a substrate.

RESULTS

Lamellar bodies were well developed in H441 cells and mRNA expression of type II cell markers and PEPT2 increased during time in culture. PEPT2 protein expression was confirmed in H441 cells, but not in A549 cells, by immunostaining and Western blotting. The uptake of Gly-Sar in H441 cells was inhibited by cefadroxil, and the cefadroxil-sensitive uptake was pH-dependent and peaked at pH 6.5. Gly-Sar uptake in H441 cells showed saturation kinetics with a Km value of 112.5 μM. In addition, apical-to-basal, but not basal-to-apical, transport of cephalexin across H441 cell monolayers was sensitive to cefadroxil.

CONCLUSIONS

PEPT2 is functionally expressed in H441 cells, making the cell line a good in vitro model to study PEPT2 function and its regulation in human distal lung.

Synthesis of cholic acid-core poly(ε-caprolactone-ran-lactide)-b-poly(ethylene glycol) 1000 random copolymer as a chemotherapeutic nanocarrier for liver cancer treatment

DTX-loaded CA-(PCL-ran-PLA)-b-PEG_1k NPs were prepared and shown great potential as drug delivery nanocarriers for cancer therapy.

New insights into the mechanism of aminoglycoside nephrotoxicity: an integrative point of view

Nephrotoxicity is one of the most important side effects and therapeutical limitations of aminoglycoside antibiotics, especially gentamicin. Despite rigorous patient monitoring, nephrotoxicity appears in 10-25% of therapeutic courses. Traditionally, aminoglycoside nephrotoxicity has been considered to result mainly from tubular damage. Both lethal and sub-lethal alterations in tubular cells handicap reabsorption and, in severe cases, may lead to a significant tubular obstruction. However, a reduced glomerular filtration is necessary to explain the symptoms of the disease. Reduced filtration is not solely the result of tubular obstruction and tubular malfunction, resulting in tubuloglomerular feedback activation; renal vasoconstriction and mesangial contraction are also crucial to fully explain aminoglycoside nephrotoxicity. This review critically presents an integrative view on the interactions of tubular, glomerular, and vascular effects of gentamicin, in the context of the most recent information available. Moreover, it discusses therapeutic perspectives for prevention of aminoglycoside nephrotoxicity derived from the pathophysiological knowledge.

Functional muscle analysis of the Tcap knockout mouse

Autosomal recessive limb-girdle muscular dystrophy type 2G (LGMD2G) is an adult-onset myopathy characterized by distal lower limb weakness, calf hypertrophy and progressive decline in ambulation. The disease is caused by mutations in Tcap, a z-disc protein of skeletal muscle, although the precise mechanisms resulting in clinical symptoms are unknown. To provide a model for preclinical trials and for mechanistic studies, we generated knockout (KO) mice carrying a null mutation in the Tcap gene. Here we present the first report of a Tcap KO mouse model for LGMD2G and the results of an investigation into the effects of Tcap deficiency on skeletal muscle function in 4- and 12-month-old mice. Muscle histology of Tcap-null mice revealed abnormal myofiber size variation with central nucleation, similar to findings in the muscles of LGMD2G patients. An analysis of a Tcap binding protein, myostatin, showed that deletion of Tcap was accompanied by increased protein levels of myostatin. Our Tcap-null mice exhibited a decline in the ability to maintain balance on a rotating rod, relative to wild-type controls. No differences were detected in force or fatigue assays of isolated extensor digitorum longus (EDL) and soleus (SOL) muscles. Finally, a mechanical investigation of EDL and SOL indicated an increase in muscle stiffness in KO animals. We are the first to establish a viable KO mouse model of Tcap deficiency and our model mice demonstrate a dystrophic phenotype comparable to humans with LGMD2G.