[Gallic acid inhibits inflammatory response of RAW264.7 macrophages by blocking the activation of TLR4/NF-κB induced by LPS]

Objective To observe the influence of gallic acid on Toll-like receptor 4/nuclear factor-κB (TLR4/NF-κB) pathway in the RAW264.7 macrophages stimulated by lipopolysaccharide (LPS). Methods RAW264.7 macrophages were divided into the following groups: control group, LPS group, LPS combined with gallic acid group, LPS combined with pyrrolidine dithiocarbamate (PDTC) group and LPS combined with dexamethasone (DM) group. RAW264.7 cells were cultured for 24 hours after corresponding treatments. The levels of tumor necrosis factor α (TNF-α), interleukin-1 (IL-1) and IL-6 were detected by ELISA. The levels of TLR4 and NF-κB mRNAs were tested by real-time PCR. The levels of p-IκBα, p65, p-p65 and TLR4 proteins were examined by Western blotting. Results The expression levels of TNF-α, IL-1 and IL-6 were up-regulated in the RAW264.7 macrophages after stimulated by LPS. Gallic acid could reduce the elevated expression levels of TNF-α, IL-1 and IL-6 induced by LPS. The expression of TLR4 significantly increased after stimulated by LPS and NF-κB was activated. Gallic acid could reverse the above changes and prevent the activation of NF-κB. Conclusion Gallic acid could inhibit LPS-induced inflammatory response in RAW264.7 macrophages via TLR4/NF-κB pathway.

Further evidence for a membrane receptor that binds glucocorticoids in the rodent hypothalamus

In parallel with their well-characterized delayed genomic effects, steroid hormones exhibit rapid, non-genomic effects at molecular, cellular and behavioral levels. We have proposed a model of rapid, non-genomic glucocorticoid inhibition of hypothalamic neuroendocrine cells through a putative membrane-associated glucocorticoid receptor (GR). Here we tested for plasma membrane GR immunoreactivity and binding in the hypothalamic supraoptic and paraventricular nuclei. Selective cross-linking of membrane proteins with membrane-impermeant BS³ and subsequent Western blot analysis with a monoclonal GR antibody revealed a reduction in the intensities of a ∼98kDa immunoreactive band and a ∼64kDa band in the rat paraventricular and supraoptic nuclei, and of a 64kDa band in hippocampal tissue, which suggested that these proteins are associated with the membrane. Saturation binding of [³H]-corticosterone and [³H]-dexamethasone in rat and mouse hypothalamic tissue revealed a K_d 4-24-fold lower and a B_max 4-7-fold lower for the membrane-associated GR compared to the intracellular GR, suggesting a lower affinity and abundance of the glucocorticoid binding sites in the membrane than in the cytosol. Together, these findings suggest the presence of a low-affinity, low-abundance membrane-associated GR in the hypothalamus that shares homology with the intracellular GR, and are consistent with physiological evidence of rapid, non-genomic glucocorticoid actions in hypothalamic neuroendocrine cells that are GR dependent.

Biomembranes from slaughterhouse blood erythrocytes as prolonged release systems for dexamethasone sodium phosphate

The present study investigated preparation of bovine and porcine erythrocyte membranes from slaughterhouse blood as bio-derived materials for delivery of dexamethasone-sodium phosphate (DexP). The obtained biomembranes, i.e., ghosts were characterized in vitro in terms of morphological properties, loading parameters, and release behavior. For the last two, an UHPLC/-HESI-MS/MS based analytical procedure for absolute drug identification and quantification was developed. The results revealed that loading of DexP into both type of ghosts was directly proportional to the increase of drug concentration in the incubation medium, while incubation at 37°C had statistically significant effect on loaded amount of DexP (P < 0.05). The encapsulation efficiency was about fivefold higher in porcine compared to bovine ghosts. Insight into ghosts' surface morphology by field emission-scanning electron microscopy and atomic force microscopy confirmed that besides inevitable effects of osmosis, DexP inclusion itself had no observable additional effect on the morphology of the ghosts carriers. DexP release profiles were dependent on erythrocyte ghost type and amount of residual hemoglobin. However, sustained DexP release was achieved and shown over 3 days from porcine ghosts and 5 days from bovine erythrocyte ghosts. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1046-1055, 2016.

Time-dependent effects of dexamethasone plasma concentrations on glucocorticoid receptor challenge tests

Glucocorticoid challenge tests such as the dexamethasone suppression test (DST) and the combined dexamethasone/corticotropin-releasing hormone (dex-CRH) test are considered to be able to sensitively measure hypothalamic-pituitary-adrenal (HPA) axis activity in stress-related psychiatric and endocrine disorders. We used mass-spectrometry to assess the relationship of plasma dexamethasone concentrations and the outcome of these tests in two independent cohorts. Dexamethasone concentrations were measured after oral ingestion of 1.5mg dexamethasone in two cohorts that underwent a standard (dexamethasone at 23:00h) as well as modified (18:00h) DST and dex-CRH test. The first study population was a case/control cohort of 105 depressed patients and 133 controls in which peripheral blood mRNA expression was also measured. The second was a cohort of 261 depressed patients that underwent a standard dex-CRH test at baseline and after 12 weeks' treatment with cognitive-behavioral therapy or antidepressants. Dexamethasone concentrations explained significant proportions of the variance in the DST in both the first (24.6%) and the second (5.2%) cohort. Dexamethasone concentrations explained a higher proportion of the variance in the dex-CRH test readouts, with 41.9% of the cortisol area under the curve (AUC) in the first sample and 24.7% in the second sample. In contrast to these strong effects at later time points, dexamethasone concentrations did not impact cortisol or ACTH concentrations or mRNA expression 3hours after ingestion. In the second sample, dexamethasone concentrations at baseline and week 12 were highly correlated, independent of treatment type and response status. Importantly, a case/control effect in the Dex-CRH test was only apparent when controlling for dexamethasone concentrations. Our results suggest that the incorporation of plasma dexamethasone concentration or measures of earlier endocrine read-outs may help to improve the assessment of endocrine dysfunction in depression.

Chronic glucocorticoids exposure enhances neurodegeneration in the frontal cortex and hippocampus via NLRP-1 inflammasome activation in male mice

Neuroinflammation plays an important role in the pathogenesis of neurodegenerative diseases, such as Alzheimer's disease (AD) and depression. Chronic glucocorticoids (GCs) exposure has deleterious effects on the structure and function of neurons and is associated with development and progression of AD. However, little is known about the proinflammatory effects of chronic GCs exposure on neurodegeneration in brain. Therefore, the aim of this study was to evaluate the effects of chronic dexamethasone (DEX) treatment (5mg/kg, s.c. for 7, 14, 21 and 28 days) on behavior, neurodegeneration and neuroinflammatory parameters of nucleotide-binding oligomerization domain-like receptor pyrin domain-containing 1 (NLRP-1) inflammasome in male mice. The results showed that DEX treatment for 21 and 28 days significantly reduced the spontaneous motor activity and exploratory behavior of the mice. In addition, these mice showed significant neurodegeneration and a decrease of microtubule-associated protein 2 (MAP2) in the frontal cortex and hippocampus CA3. DEX treatment for 7, 14, 21 and 28 days significantly decreased the mRNA and protein expression of glucocorticoid receptor (GR). Moreover, DEX treatment for 21 and 28 days significantly increased the proteins expression of NLRP-1, Caspase-1, Caspase-5, apoptosis associated speck-like protein (ASC), nuclear factor-κB (NF-κB), p-NF-κB, interleukin-1β (IL-1β), IL-18 and IL-6 in the frontal cortex and hippocampus brain tissue. DEX treatment for 28 days also significantly increased the mRNA expression levels of NLRP-1, Caspase-1, ASC and IL-1β. These results suggest that chronic GCs exposure may increase brain inflammation via NLRP-1 inflammasome activation and induce neurodegeneration.

A Mixed Glucocorticoid/Mineralocorticoid Selective Modulator With Dominant Antagonism in the Male Rat Brain

Adrenal glucocorticoid hormones are potent modulators of brain function in the context of acute and chronic stress. Both mineralocorticoid (MRs) and glucocorticoid receptors (GRs) can mediate these effects. We studied the brain effects of a novel ligand, C118335, with high affinity for GRs and modest affinity for MRs. In vitro profiling of receptor-coregulator interactions suggested that the compound is a "selective modulator" type compound for GRs that can have both agonistic and antagonistic effects. Its molecular profile for MRs was highly similar to those of the full antagonists spironolactone and eplerenone. C118335 showed predominantly antagonistic effects on hippocampal mRNA regulation of known glucocorticoid target genes. Likewise, systemic administration of C118335 blocked the GR-mediated posttraining corticosterone-induced enhancement of memory consolidation in an inhibitory avoidance task. Posttraining administration of C118335, however, gave a strong and dose-dependent impairment of memory consolidation that, surprisingly, reflected involvement of MRs and not GRs. Finally, C118335 treatment acutely suppressed the hypothalamus-pituitary-adrenal axis as measured by plasma corticosterone levels. Mixed GR/MR ligands, such as C118335, can be used to unravel the mechanisms of glucocorticoid signaling. The compound is also a prototype of mixed GR/MR ligands that might alleviate the harmful effects of chronic overexposure to endogenous glucocorticoids.

Bovine herpesvirus 1 productive infection and immediate early transcription unit 1 promoter are stimulated by the synthetic corticosteroid dexamethasone

The primary site for life-long latency of bovine herpesvirus 1 (BHV-1) is sensory neurons. The synthetic corticosteroid dexamethasone consistently induces reactivation from latency; however the mechanism by which corticosteroids mediate reactivation is unclear. In this study, we demonstrate for the first time that dexamethasone stimulates productive infection, in part, because the BHV-1 genome contains more than 100 potential glucocorticoid receptor (GR) response elements (GREs). Immediate early transcription unit 1 (IEtu1) promoter activity, but not IEtu2 or VP16 promoter activity, was stimulated by dexamethasone. Two near perfect consensus GREs located within the IEtu1 promoter were necessary for dexamethasone-mediated stimulation. Electrophoretic mobility shift assays and chromatin immunoprecipitation studies demonstrated that the GR interacts with IEtu1 promoter sequences containing the GREs. Although we hypothesize that DEX-mediated stimulation of IEtu1 promoter activity is important during productive infection and perhaps reactivation from latency, stress likely has pleiotropic effects on virus-infected cells.

Helix 8 of the ligand binding domain of the glucocorticoid receptor (GR) is essential for ligand binding

Membrane association of estrogen receptors (ER) depends on cysteine palmitoylation and two leucines in the ligand binding domain (LBD), conserved in most steroid receptors. The role of this region, corresponding to helix 8 of the glucocorticoid receptor (GR) LBD, on membrane association of GR was studied in 4B cells, expressing endogenous GR, and Cos-7 cells transfected EGFP-GR constructs. 4B cells preloaded with radiolabeled palmitic acid showed no radioactivity incorporation into immunoprecipitated GR. Moreover, mutation C683A (corresponding to ER palmitoylation site) did not affect corticosterone-induced membrane association of GR. Mutations L687-690A, L682A, E680G and K685G prevented membrane and also nuclear localization through reduced ligand binding. L687-690A mutation decreased association of GR with heat shock protein 90 and transcriptional activity, without overt effects on receptor protein stability. The data demonstrate that palmitoylation does not mediate membrane association of GR, but that the region 680-690 (helix 8) is critical for ligand binding and receptor function.

Scales tell a story on the stress history of fish

Fish faced with stressful stimuli launch an endocrine stress response through activation of the hypothalamic-pituitary-interrenal (HPI-) axis to release cortisol into the blood. Scientifically validated biomarkers to capture systemic cortisol exposure over longer periods of time are of utmost importance to assess chronic stress in governmental, wildlife, aquaculture and scientific settings. Here we demonstrate that cortisol in scales of common carp (Cyprinus carpio L.) is the long-sought biomarker for chronic stress. Undisturbed (CTR) and daily stressed (STRESS) carp were compared. Dexamethasone (DEX) or cortisol (CORT) fed fish served as negative and positive controls, respectively. Scale cortisol was quantified with a validated ultra-performance liquid chromatography tandem mass spectrometry method. An increase in scale cortisol content was found in STRESS and CORT but not in CTR and DEX fish. Scale cortisol content reflects its accumulation in a stressor and time dependent manner and validates the scale cortisol content as biomarker for chronic stress. Plasma analyses confirmed that (i) CTR, DEX and CORT treatments were effective, (ii) plasma cortisol of STRESS fish showed no signs of chronic HPI-axis activation, and (iii) plasma cortisol is a poor predictor for chronic stress. The expression of HPI key genes crf, pomc, and star were up-regulated in STRESS fish in the absence of a plasma cortisol response, as was the target gene of cortisol encoding subunit α1 of the Na⁺/K⁺-ATPase in gills. When lost, scales of fish regenerate fast. Regenerated scales corroborate our findings, offering (i) unsurpassed time resolution for cortisol incorporation and as such for stressful events, and (ii) the possibility to investigate stress in a well defined and controlled environment and time frame creating novel opportunities for bone physiological research. We conclude that the cortisol content in ontogenetic and regenerated scales is an innovative biomarker for chronic stress offering ample applications in science and industry.

Inhibition of proteasome-mediated glucocorticoid receptor degradation restores nitric oxide bioavailability in myocardial endothelial cells in vitro

BACKGROUND INFORMATION

Glucocorticoids (GCs), including the synthetic GC derivate dexamethasone, are widely used as immunomodulators. One of the numerous side effects of dexamethasone therapy is hypertension arising from reduced release of the endothelium-derived vasodilator nitric oxide (NO).

RESULTS

Herein, we described the role of dexamethasone and its glucocorticoid receptor (GR) in the regulation of NO synthesis in vitro using the mouse myocardial microvascular endothelial cell line, MyEND. GC treatment caused a firm decrease of extracellular NO levels, whereas the expression of endothelial NO synthase (eNOS) was not affected. However, GC application induced an impairment of tetrahydrobiopterin (BH4 ) concentrations as well as GTP cyclohydrolase-1 (GTPCH-1) expression, both essential factors for NO production upstream of eNOS. Moreover, dexamethasone stimulation resulted in a substantially decreased GR gene and protein expression in MyEND cells. Importantly, inhibition of proteasome-mediated proteolysis of the GR or overexpression of an ubiquitination-defective GR construct improved the bioavailability of BH4 and strengthened GTPCH-1 expression and eNOS activity.

CONCLUSIONS

Summarising our results, we propose a new mechanism involved in the regulation of NO signalling by GCs in myocardial endothelial cells. We suggest that a sufficient GR protein expression plays a crucial role for the management of GC-induced harmful adverse effects, including deregulations of vasorelaxation arising from disturbed NO biosynthesis.

Preparation and in vitro evaluation of a pluronic lecithin organogel containing ricinoleic acid for transdermal delivery

The present study deals with the preparation and in vitro evaluation of a Pluronic lecithin organogel gel containing ricinoleic acid for transdermal delivery. Blank Pluronic lecithin organogel gels were prepared using ricinoleic acid as the oil phase and characterized for pH, viscosity, gelation temperature, and microscopic structure. The optimized Pluronic lecithin organogel gel formulation was further evaluated using ketoprofen (10%) and dexamethasone (0.5%) as model drugs. The stability and in vitro permeability of ketoprofen and dexamethasone was evaluated and compared with the corresponding control formulation (Pluronic lecithin organogel gel made with isopropyl palmitate as the oil phase). The pH and viscosity of blank Pluronic lecithin organogel gel prepared with ricinoleic acid was comparable with the isopropyl palmitate Pluronic lecithin organogel gel. The thixotropic property of ricinoleic acid Pluronic lecithin organogel gel was found to be better than the control. Drug-loaded Pluronic lecithin organogel gels behaved in a similar manner and all formulations were found to be stable at 25 degrees C, 35 degrees C, and 40 degrees C for up to 35 days. The penetration profile of dexamethasone was similar from both the Pluronic lecithin organogel gels, while the permeability for ketoprofen from Pluronic lecithin organogel gel containing ricinoleic acid was found to be three times higher as compared to the control formulation.

Competitive interactions of anti-carcinogens with serum albumin: a spectroscopic study of bendamustine and dexamethasone with the aid of chemometrics

Interactions between the anti-carcinogens, bendamustine (BDM) and dexamethasone (DXM), with bovine serum albumin (BSA) were investigated with the use of fluorescence and UV-vis spectroscopies under pseudo-physiological conditions (Tris-HCl buffer, pH 7.4). The static mechanism was responsible for the fluorescence quenching during the interactions; the binding formation constant of the BSA-BDM complex and the binding number were 5.14×10(5)Lmol(-1) and 1.0, respectively. Spectroscopic studies for the formation of BDM-BSA complex were interpreted with the use of multivariate curve resolution - alternating least squares (MCR-ALS), which supported the complex formation. The BSA samples treated with site markers (warfarin - site I and ibuprofen - site II) were reacted separately with BDM and DXM; while both anti-carcinogens bound to site I, the binding constants suggested that DXM formed a more stable complex. Relative concentration profiles and the fluorescence spectra associated with BDM, DXM and BSA, were recovered simultaneously from the full fluorescence excitation-emission data with the use of the parallel factor analysis (PARAFAC) method. The results confirmed that on addition of DXM to the BDM-BSA complex, the BDM was replaced and the DXM-BSA complex formed; free BDM was released. This finding may have consequences for the transport of these drugs during any anti-cancer treatment.

A dexamethasone prodrug reduces the renal macrophage response and provides enhanced resolution of established murine lupus nephritis

We evaluated the ability of a macromolecular prodrug of dexamethasone (P-Dex) to treat lupus nephritis in (NZB × NZW)F1 mice. We also explored the mechanism underlying the anti-inflammatory effects of this prodrug. P-Dex eliminated albuminuria in most (NZB × NZW)F1 mice. Furthermore, P-Dex reduced the incidence of severe nephritis and extended lifespan in these mice. P-Dex treatment also prevented the development of lupus-associated hypertension and vasculitis. Although P-Dex did not reduce serum levels of anti-dsDNA antibodies or glomerular immune complexes, P-Dex reduced macrophage recruitment to the kidney and attenuated tubulointerstitial injury. In contrast to what was observed with free dexamethasone, P-Dex did not induce any deterioration of bone quality. However, P-Dex did lead to reduced peripheral white blood cell counts and adrenal gland atrophy. These results suggest that P-Dex is more effective and less toxic than free dexamethasone for the treatment of lupus nephritis in (NZB × NZW)F1 mice. Furthermore, the data suggest that P-Dex may treat nephritis by attenuating the renal inflammatory response to immune complexes, leading to decreased immune cell infiltration and diminished renal inflammation and injury.

miRNA-374 regulates dexamethasone-induced differentiation of primary cultures of porcine adipocytes

To investigate the effect of glucocorticoid on adipocytes metabolism and miRNAs that may be involved in adipocyte differentiation, primary porcine preadipocytes were treated with 10-6 M dexamethasone and RU486 (a glucocorticoid receptor antagonist) for 48 h. PPAR-γ (peroxisome proliferators-activated receptor-γ), and C/EBP-β (CCTTA enhancer binding protein-β) gene and protein expression were measured. The expressions of miRNAs predicted to directly target C/EBP-β were determined, and the functions of the potential miRNAs were verified. The results showed that the triglyceride content in cultured adipocytes increased significantly after 10-6 M dexamethasone treatment for 48 h, whereas the cell viability did not differ among the four groups (

CONTROL

10-6 M dexamethasone; 10-6 M RU486: 10-6 M dexamethasone+10-6 M RU486) (p>0.05). Cells treated with dexamethasone for 48 h significantly upregulated perilipin and PPAR-γ gene expression, and PPAR-γ protein expression was also significantly increased. However, C/EBP-β mRNA and protein expression levels were significantly decreased. Both miR-374a and miR-374b, targeting the C/EBP-β 3'-UTR (3'-untranslated region), were significantly increased. Dual luciferase activity assay results indicated that miR-374a/b was directly recognised and bound to the 3'-UTR of C/EBP-β and thereby suppressed C/EBP-β gene expression. The present study showed that 10-6 M dexamethasone promotes lipid accumulation in primary cultures of porcine preadipocytes. PPAR-γ and C/EBP-β protein abundance showed differences after 48 h dexamethasone treatment; miR-374a/b may be involved in regulating of C/EBP-β expression. These results provide new targets for further regulation of porcine lipid metabolism.

Multi-ligand poly(L-lactic-co-glycolic acid) nanoparticles inhibit activation of endothelial cells

Endothelial cell (EC) activation and inflammation is a key step in the initiation and progression of many cardiovascular diseases. Targeted delivery of therapeutic reagents to inflamed EC using nanoparticles is challenging as nanoparticles do not arrest on EC efficiently under high shear stress. In this study, we developed a novel polymeric platelet-mimicking nanoparticle for strong particle adhesion onto ECs and enhanced particle internalization by ECs. This nanoparticle was encapsulated with dexamethasone as the anti-inflammatory drug, and conjugated with polyethylene glycol, glycoprotein 1b, and trans-activating transcriptional peptide. The multi-ligand nanoparticle showed significantly greater adhesion on P-selectin, von Willebrand Factor, than the unmodified particles, and activated EC in vitro under both static and flow conditions. Treatment of injured rat carotid arteries with these multi-ligand nanoparticles suppressed neointimal stenosis more than unconjugated nanoparticles did. These results indicate that this novel multi-ligand nanoparticle is efficient to target inflamed EC and inhibit inflammation and subsequent stenosis.

Stimulation of mouse Cyp1b1 during adipogenesis: characterization of promoter activation by the transcription factor Pax6

Cytochrome P4501B1 (Cyp1b1) is expressed specifically in certain neural crest (NC) cells during embryogenesis. Mesenchymal progenitor cells that develop from NC cells are modeled here by mouse C3H10T1/2 and 3T3-L1 cells. Dexamethasone in combination with methylisobutylxanthine (DM) induces Cyp1b1 and a 6.7 kb mouse Cyp1b1 promoter-luciferase reporter in each cell type prior to adipogenesis. An 18 base sequence (at -6.11 kb) (PaxE) which was essential for this reporter stimulation in 3T3-L1 cells bound the transcription factor Pax6. This is shown by gel mobility shifts and sequence mutations. Heterologous vector expression of Pax6 in 3T3-L1 cells enhanced DM stimulated Cyp1b1 promoter activity through cooperation with two Sp1 sites in the proximal promoter region. Chromatin immunoprecipitation showed that DM stimulated binding of Pax6 adjacent to Sp1 in the proximal promoter more than in the PaxE region. The Cyp1b1 induction by DM in C3H10T1/2 cells was more rapid but independent of Pax6. The far upstream enhancer region (FUER) found in rat Cyp1b1 responded to DM but was inactive in the mouse promoter due to key sequence changes. The expression patterns of Pax6 and Cyp1b1 frequently overlap during mouse embryogenesis. The relationship between Pax6 and Cyp1b1 expression warrants further investigation, particularly in the NC.

Inherent sex-dependent regulation of human hepatic CYP3A5

BACKGROUND AND PURPOSE

Expression of hepatic cytochromes P450 (CYP) in all species examined, including humans, is generally sexually dimorphic. We examined the sex-dependent expression of CYP3A5 and the hormone-regulated molecular mechanism(s) responsible for any dimorphism.

EXPERIMENTAL APPROACH

CYP3A5 levels as well as nuclear translocation and promoter binding of transcription factors regulating CYP3A5 expression were measured in primary hepatocyte cultures derived from men and women exposed to physiological-like levels of growth hormone alone, dexamethasone alone and the combined regimen.

KEY RESULTS

We observed a dramatic inherent CYP3A5 sexual dimorphism (women > men) with all treatments as a result of a ~2-fold greater level of hormone-induced activation and nuclear accumulation of hepatocyte nuclear factor-4α (HNF-4α), pregnane X receptor (PXR) and retinoic X receptorα (RXRα) in female hepatocytes. Furthermore, PXR : RXRα exhibited significantly higher DNA binding levels to its specific binding motif on the CYP3A5 promoter in female hepatocytes, inferring a possible explanation for the elevated expression of the isoform in women. Results from experiments using HepG2 cells treated with siRNA-induced knockdown of HNF-4α and/or transfected with luciferase reporter constructs containing the CYP3A5 promoter were in agreement with the basic mechanism observed in primary hepatocytes of both sexes.

CONCLUSIONS AND IMPLICATIONS

Female-predominant expression of human CYP3A5 is due to an inherent, sex-dependent suboptimal activation of the transcription networks responsible for hormone-induced expression of the isoform in men. Accordingly, in conjunction with previous studies of other human CYPs, men and women are intrinsically unlikely to handle many drugs in the same way; thus, sex should be a requisite component factored into the design of personalized drug therapies.

Changes in the brain accumulation of glucocorticoids in abcb1a-deficient CF-1 mice

The multidrug resistance transporter, P-glycoprotein (P-gp), contributes to highly lipophilic molecules penetrating the brain from the blood at a much lower rate than expected, and has numerous substrates, inhibitors and modulators. The drug-transporting isoform of P-gp is coded by a single human gene, ABCB1, and shares 80% homology with the murine drug-transporting isoforms, abcb1a and abcb1b, which share 92% homology with each other. Although these murine isoforms are highly similar, there are known affinity differences between the isoforms, and the localisation of the two isoforms in the brain is also disputed. Studies using mice genetically modified to be deficient in one or both isoforms of P-gp have also resulted in conflicting data. The contribution of the abcb1a isoform, which is considered to contribute most to the central nervous system (CNS)-protective role of P-gp, is investigated in the present study using CF-1-abcb1a(-/-) mice and the well-established brain/choroid plexus perfusion technique. Twenty-minute in situ brain/choroid plexus perfusions in CF-1-abcb1a(-/-) mice indicated the increased accumulation of [(3) H]cortisol, [(3) H]corticosterone and [(3) H]dexamethasone in most of the brain regions examined compared to CF-1-abcb1a(+/+) mice. Taken together with our earlier published studies in abcb1a/b(-/-) mice, these data strongly suggest that the in vivo CNS accumulation of glucocorticoids obtained using single knockout strains [e.g. abcb1a(-/-)] cannot be directly compared with those obtained in double knockout strains [e.g. abcb1a/b(-/-)].

Graphical process design tools for iontophoretic transdermal drug-delivery devices

A graphical procedure was proposed for the optimum design of transdermal drug-delivery systems enhanced by iontophoresis. Contour plots displayed the relationships among steady-state plasma level, current density and initial drug concentration in a vehicle. This information was combined with a closed-form expression of the process time constant, estimated as the medicament in the blood reaches a plateau after application of the electric field. Analysis was conducted using Laplace-transformed variables and did not require time-domain solutions. Simulation results show that a current density of 0.044 mA/cm(2) and a loading of 3500 μg/ml of dexamethasone sodium m-sulfobenzoate were necessary to achieve an equilibrium plasma concentration of 1.254 ng/cm(3) with a time constant of 8.34 h.

Proinflammatory actions of glucocorticoids: glucocorticoids and TNFα coregulate gene expression in vitro and in vivo

Synthetic glucocorticoids are widely used for treatment of many inflammatory diseases. However, long-term glucocorticoid treatment can cause a variety of negative side effects. A genome-wide microarray analysis was performed in human lung A549 cells to identify genes regulated by both the antiinflammatory steroid dexamethasone (Dex) and the proinflammatory cytokine TNFα. Unexpectedly, we discovered that numerous genes were coregulated by treatment with both Dex and TNFα. We evaluated the mechanism of coregulation of one of these genes, serpinA3 (α-1 antichymotrypsin), a secreted, acute phase protein strongly associated with numerous inflammatory diseases. Up-regulation of serpinA3 requires the presence of both the glucocorticoid receptor and TNFα soluble receptor 1. Treatment with Dex or TNFα resulted in a 10- to 25-fold increase of serpinA3 mRNA, whereas coadministration of Dex and TNFα led to a synergistic increase in serpinA3 mRNA. The naturally occurring glucocorticoid, cortisol, also resulted in a synergistic increase in serpinA3 mRNA levels in A549 cells. Furthermore, in vivo treatment of C57BL/6 mice with Dex and TNFα resulted in coregulation of serpinA3 mRNA levels in both lung and liver tissues. Finally, chromatin immunoprecipitation analyses suggest that glucocorticoid receptor binding to the serpinA3 transcriptional start site can be enhanced by the combination of Dex plus TNFα treatment of A549 cells. These studies demonstrate that glucocorticoids and proinflammatory compounds can coregulate genes associated with human disease. This discovery may underlie the basis of some of the adverse effects associated with long-term glucocorticoid therapy.

Effect of size on the cellular endocytosis and controlled release of mesoporous silica nanoparticles for intracellular delivery

Due to the unique physicochemical properties and membrane-permeable capacity, mesoporous silica nanoparticles (MSNs) are considered as an ideal carrier for intracellular delivery. Herein, we endeavored to address the size effect of MSNs on the cellular uptake, endosomal escape and controlled release, the key steps for the intracellular delivery. The well-ordered MSNs in the range from 55-nm to 440-nm with similar pore texture were prepared by modified base-catalyzed sol-gel method. With MC3T3-E1 model cell line, the in vitro results indicated that after 12 h cultivation, MSNs within 55 ~ 440 nm could all be internalized into the cells, and further escaped out of the endosomal compartment. The efficiency of the cellular uptake and endosomal escape strongly depended on the particle size, with the best efficiencies from 100-nm MSNs. Furthermore, the MTT results indicated that these MSNs materials were all biocompatible. The controlled release experiments with hydrophobic dexamethasone and hydrophilic vitamin C as models showed that for these small-molecular drugs, the loading amount all mainly determined by the surface area of the MSNs, and the subsequent release of the drug dramatically decreased with the increasing of the particle size. By contrast, the release rate of vitamin C was much quicker than that of the dexamethasone. These findings presented here could provide new means to tailor the size of MSNs and thus to guide the design of MSNs-based intracellular delivery system. Due to the good cell biocompatibility, high cellular uptake and endosomal escape, we conjectured that the 100-nm MSNs are more favorable for the intracellular delivery of drugs in live cells.

Semi-automatic counting of connexin 32s immunolocalized in cultured fetal rat hepatocytes using image processing

Connexin 32s (Cx32s) were immunolocalized in fetal rat hepatocytes and their distribution was determined qualitatively. We used image analysis using a quantitative index (QI) of Cx32 (QI Cx32) defined as the area of Cx32s/number of cells in cultured fetal rat hepatocytes. Hepatocytes from livers of fetal rats were separated by collagenase digestion and low centrifugation on gestational day 17. Cells were cultured for 3 days in dexamethasone (DEX)-supplemented medium (Dex0). The medium was replaced with fresh medium and cells were continuously cultured for 3 days with DEX or epidermal growth factor supplemented medium (Dex3 or EGF3). After culture termination, cells were fixed and stained using the fluorescein-labeled antibody method for Cx32s and diaminophenylindole staining for nuclei. Thirty pairs of histological images for Cx32s and nuclei, 180 images in total, were obtained from each condition. The QI Cx32 significantly increased from 284.1 ± 102.0 (mean and SD, n=26) of Dex0 to 428.9 ± 101.0 of Dex3 (n=28) (P<0.05, Kruskal-Wallis test, then Steel-Dwass test). The increase of QI Cx32 was compatible with the morphological observations. The image analysis processing time after preparation for 180 images was reduced from 8h needed for manual operations to 1 min using ImageJ software with our macro routine.

First evidence for the presence of efflux pump in the earthworm Eisenia andrei

Efflux pumps are transport proteins involved in the extrusion of toxic substrates from cells to the external environment. Activities of efflux pumps have been found in many organisms, however such activity has not been evidenced in earthworms. Adult Eisenia andrei earthworms were exposed to efflux modulators - verapamil (a known inhibitor of efflux pump protein) and dexamethasone (a known inducer of efflux activity) - and the amount of absorbed fluorescent dye rhodamine B was measured. The results showed that verapamil inhibited efflux activity and decreased removal of rhodamine B, whereas dexamethasone induced efflux activity and increased removal of rhodamine B. This is the first evidence of the presence of efflux pump in earthworm Eisenia andrei. Since earthworms are often used as test organisms due to their sensitive reactions towards environmental influences, the discovery of efflux pump activity can contribute to the better understanding of toxicity of certain pollutants.

Altered sirtuin deacetylase gene expression in patients with a mood disorder

Sirtuins are a family of NAD+-dependent enzymes that regulate cellular functions through deacetylation of various proteins. Although recent reports have suggested an important role of deacetylases (i.e., histone deacetylases) in mood disorders and antidepressant action, the involvement of sirtuins in the pathophysiology of mood disorders is largely unknown. In this study, we aimed to determine whether there are alterations in sirtuin mRNA expression in peripheral white blood cells of patients with a mood disorder. Also, to examine whether the altered sirtuin mRNA expression is state- or trait-dependent, mood disorder patients who were in a remissive state were assessed. We used quantitative real-time polymerase chain reaction to measure the mRNA levels of seven sirtuin isoforms (SIRT1-7) in peripheral white blood cells of patients with major depressive disorder (MDD) or bipolar disorder (BPD) during depressive and remissive states and in normal healthy subjects. The SIRT1, 2 and 6 mRNA levels in MDD and BPD patients decreased significantly in those who were in a depressive state compared to healthy controls, whereas the expression of those mRNAs in both MDD and BPD of patients in a remissive state were comparable to those in healthy controls. Thus, our data suggest that altered SIRT1, 2 and 6 expression is state-dependent and might be associated with the pathogenesis and/or pathophysiology of mood disorders.