Barriers that Inhaled Particles Encounter.

Inhalable particulate drug carriers-nano- and micro-particles, liposomes, and micelles-should be designed to promote drug deposition in the lung and engineered to exhibit the desired drug release property. To deposit at the desired site of action, inhaled particles must evade various lines of lung defense, including mucociliary clearance, entrapment by mucus layer, and phagocytosis by alveolar macrophages. Various physiological, mechanical, and chemical barriers of the respiratory system reduce particle residence time in the lungs, prevent particle deposition in the deep lung, remove drug-filled particles from the lung, and thus diminish the therapeutic efficacy of inhaled drugs. To develop inhalable drug carriers with efficient deposition properties and optimal retention in the lungs, particle engineers should have a thorough understanding of the barriers that particles confront and appreciate the lung defenses that remove the particles from the respiratory system. Thus, this section summarizes the mechanical, chemical, and immunological barriers of the lungs that inhaled particles must overcome and discusses the influence of these barriers on the fate of inhaled particles.

ANGPTL7, a therapeutic target for increased intraocular pressure and glaucoma.

Glaucoma is a leading cause of blindness. Current glaucoma medications work by lowering intraocular pressure (IOP), a risk factor for glaucoma, but most treatments do not directly target the pathological changes leading to increased IOP, which can manifest as medication resistance as disease progresses. To identify physiological modulators of IOP, we performed genome- and exome-wide association analysis in >129,000 individuals with IOP measurements and extended these findings to an analysis of glaucoma risk. We report the identification and functional characterization of rare coding variants (including loss-of-function variants) in ANGPTL7 associated with reduction in IOP and glaucoma protection. We validated the human genetics findings in mice by establishing that Angptl7 knockout mice have lower (~2 mmHg) basal IOP compared to wild-type, with a trend towards lower IOP also in heterozygotes. Conversely, increasing murine Angptl7 levels via injection into mouse eyes increases the IOP. We also show that acute Angptl7 silencing in adult mice lowers the IOP (~2-4 mmHg), reproducing the observations in knockout mice. Collectively, our data suggest that ANGPTL7 is important for IOP homeostasis and is amenable to therapeutic modulation to help maintain a healthy IOP that can prevent onset or slow the progression of glaucoma.

Calcium-Sensing Receptor Contributes to Hyperoxia Effects on Human Fetal Airway Smooth Muscle.

Supplemental O2 (hyperoxia), necessary for maintenance of oxygenation in premature infants, contributes to neonatal and pediatric airway diseases including asthma. Airway smooth muscle (ASM) is a key resident cell type, responding to hyperoxia with increased contractility and remodeling [proliferation, extracellular matrix (ECM) production], making the mechanisms underlying hyperoxia effects on ASM significant. Recognizing that fetal lungs experience a higher extracellular Ca2+ ([Ca2+]o) environment, we previously reported that the calcium sensing receptor (CaSR) is expressed and functional in human fetal ASM (fASM). In this study, using fASM cells from 18 to 22 week human fetal lungs, we tested the hypothesis that CaSR contributes to hyperoxia effects on developing ASM. Moderate hyperoxia (50% O2) increased fASM CaSR expression. Fluorescence [Ca2+]i imaging showed hyperoxia increased [Ca2+]i responses to histamine that was more sensitive to altered [Ca2+]o, and promoted IP3 induced intracellular Ca2+ release and store-operated Ca2+ entry: effects blunted by the calcilytic NPS2143. Hyperoxia did not significantly increase mitochondrial calcium which was regulated by CaSR irrespective of oxygen levels. Separately, fASM cell proliferation and ECM deposition (collagens but not fibronectin) showed sensitivity to [Ca2+]o that was enhanced by hyperoxia, but blunted by NPS2143. Effects of hyperoxia involved p42/44 ERK via CaSR and HIF1α. These results demonstrate functional CaSR in developing ASM that contributes to hyperoxia-induced contractility and remodeling that may be relevant to perinatal airway disease.

Development of pharmaceutically scalable inhaled anti-cancer nanotherapy - Repurposing amodiaquine for non-small cell lung cancer (NSCLC).

New drug and dosage form development faces significant challenges, especially in oncology, due to longer development cycle and associated scale-up complexities. Repurposing of existing drugs with potential anti-cancer activity into new therapeutic regimens provides a feasible alternative. In this project, amodiaquine (AQ), an anti-malarial drug, has been explored for its anti-cancer efficacy through formulating inhalable nanoparticulate systems using high-pressure homogenization (HPH) with scale-up feasibility and high reproducibility. A 32 multifactorial design was employed to better understand critical processes (probe homogenization speed while formulating coarse emulsion) and formulation parameters (concentration of cationic polymer in external aqueous phase) so as to ensure product quality with improved anticancer efficacy in non-small cell lung cancer (NSCLC). Optimized AQ loaded nanoparticles (AQ NP) were evaluated for physicochemical properties, stability profile, in-vitro aerosol deposition behavior, cytotoxic potential against NSCLC cells in-vitro and in 3D simulated tumor spheroid model. The highest probe homogenization speed (25,000 rpm) resulted in lower particle size. Incorporation of cationic polymer, polyethylenimine (0.5% w/v) resulted in high drug loading efficiencies at optimal drug quantity of 5 mg. Formulated nanoparticles (liquid state) exhibited an aerodynamic diameter of 4.7 ± 0.1 µm and fine particle fraction of 81.0 ± 9.1%, indicating drug deposition in the respirable airways. Cytotoxicity studies in different NSCLC cell lines revealed significant reduction in IC50 values with AQ-loaded nanoparticles compared to plain drug, along with significant cell migration inhibition (scratch assay) and reduced % colony growth (clonogenic assay) in A549 cells with AQ NP. Moreover, 3D simulated spheroid studies revealed efficacy of nanoparticles in penetration to tumor core, and growth inhibition. AQ's autophagy inhibition ability significantly increased (increased LC3B-II levels) with nanoparticle encapsulation, along with moderate improvement in apoptosis induction (Caspase-3 levels). No impact was observed on HUVEC angiogenesis suggesting alternative anticancer mechanisms. To conclude, amodiaquine can be a promising candidate for repurposing to treat NSCLC while delivering inhalable nanoparticles developed using a scalable HPH process. Despite the involvement of complex parameters, application of DoE has simplified the process of product and process optimization.

Class C GPCRs in the airway.

Understanding and targeting of GPCRs remain a critical aspect of airway pharmacology and therapeutics for diseases such as asthma or COPD. Most attention has been on the large Class A GPCRs towards improved bronchodilation and blunting of remodeling. Better known in the central or peripheral nervous system, there is increasing evidence that Class C GPCRs which include metabotropic glutamate and GABA receptors, the calcium sensing receptor, sweet/umami taste receptors and a number of orphan receptors, can contribute to airway structure and function. In this review, we will summarize current state of knowledge regarding the pharmacology of Class C GPCRs, their expression and potential functions in the airways, and the application of pharmacological agents targeting this group in the context of airway diseases.

Effects of a New Topical Treatment Containing Several Hair Growth Promoters in Women with Early Female Pattern Hair Loss.

BACKGROUND: Female pattern hair loss (FPHL) is increasing ly common and often presents with hair shedding. Spec tral. DNC-N® contains anti-inflammatory actives and hair growth promoters. OBJECTIVES: To assess the efficacy and tolerability of Spectral DNC-N® (DS Laboratories, Inc.) in women with early FPHL and excessive shedding. METHODS: Forty-nine patients were treated with Spectral DNC-N®, applied twice daily for 3 months; 28 patients were included in the 3-month treatment extension. Efficacy assessments included the degree of hair shedding using the validated hair shedding visual scale, hair mass index (HMI), and photographic evaluation. RESULTS: There was a statistically significant decrease in hair shedding and a corresponding increase in HMI by month 3, which was maintained through month 6. The mean investigator-assessed hair shedding score decreased from 3.5 to 2.0 and the hair mass increased from 75.8 to 84.3 mm>sup<2>/supsup<2>/sup< by month 3 (both p < 0.01 compared with baseline). By month 6, the hair shedding score was reduced to 1.6 and the hair mass was maintained. Most patients (75%) showed an increase in global hair density. CONCLUSIONS: Spectral. DNC-N® significantly reduced hair shedding, with a corresponding increase in hair mass and density. These effects were already evident after 3 months' treatment and further improved in those patients who continued treatment to month 6. Tolerability was good and patient satisfaction levels were high.

Prostaglandin E2, but not cAMP nor ß2-agonists, induce tristetraprolin (TTP) in human airway smooth muscle cells.

Tristetraprolin (TTP) is an anti-inflammatory molecule known to post-transcriptionally regulate cytokine production and is, therefore, an attractive drug target for chronic respiratory diseases driven by inflammation, such as asthma and chronic obstructive pulmonary disease. Our recent in vitro studies in primary human airway smooth (ASM) cells have confirmed the essential anti-inflammatory role played by TTP as a critical partner in a cytokine regulatory network. However, several unanswered questions remain. While prior in vitro studies have suggested that TTP is regulated in a cAMP-mediated manner, raising the possibility that this may be one of the ways in which ß2-agonists achieve beneficial effects beyond bronchodilation, the impact of ß2-agonists on ASM cells is unknown. Furthermore, the effect of prostaglandin E2 (PGE2) on TTP expression in ASM cells has not been reported. We address this herein and reveal, for the first time, that TTP is not regulated by cAMP-activating agents nor following treatment with long-acting ß2-agonists. However, PGE2 does induce TTP mRNA expression and protein upregulation in ASM cells. Although the underlying mechanism of action remains undefined, we can confirm that PGE2-induced TTP upregulation is not mediated via cAMP, or EP2/EP4 receptor activation, and occurred in a manner independent of the p38 MAPK-mediated pathway. Taken together, these data confirm that ß2-agonists do not upregulate TTP in human ASM cells and indicate that another way in which PGE2 may achieve beneficial effects in asthma and COPD may be via upregulation of the master controller of inflammation-TTP.

Doxofylline does not increase formoterol-induced cAMP nor MKP-1 expression in ASM cells resulting in lack of anti-inflammatory effect.

The xanthine doxofylline has been examined in clinical trials and shown to have efficacy and greater tolerability than theophylline in asthma and chronic obstructive pulmonary disease. The 'novofylline' doxofylline has demonstrated bronchodilatory and anti-inflammatory actions in in vivo and ex vivo experimental models of respiratory disease. However, there are limited studies in vitro. We address this herein and examine whether doxofylline has anti-inflammatory impact on primary cultures of airway smooth muscle (ASM) cells. We conduct a series of investigations comparing and contrasting doxofylline with the archetypal xanthine, theophylline, and the specific phosphodiesterase (PDE) 4 inhibitor, cilomilast. We confirm that the xanthine drugs do not have action as PDE inhibitors in ASM cells. Unlike cilomilast, doxofylline (and theophylline) do not increase cAMP production in ASM cells induced by long-acting ß2-agonist formoterol. Similar to theophylline, and consistent with the lack of cAMP potentiation, doxofylline does not augment formoterol-induced upregulation of the anti-inflammatory protein mitogen-activated protein kinase phosphatase 1 (MKP-1). However, when we examine the effect of doxofylline on secretion of the interleukin 8 from ASM cells stimulated by tumour necrosis factor (an in vitro surrogate measure of inflammation), there was no repression of inflammation. This is in contrast to the anti-inflammatory impact exerted by theophylline and cilomilast in confirmatory experiments. In summary, our study is the first to examine the effect of doxofylline on ASM cells in vitro and highlights some distinct differences between two key members of xanthine drug family, doxofylline and theophylline.

Inhaled sildenafil as an alternative to oral sildenafil in the treatment of pulmonary arterial hypertension (PAH).

The practice of treating PAH patients with oral or intravenous sildenafil suffers from the limitations of short dosing intervals, peripheral vasodilation, unwanted side effects, and restricted use in pediatric patients. In this study, we sought to test the hypothesis that inhalable poly(lactic-co-glycolic acid) (PLGA) particles of sildenafil prolong the release of the drug, produce pulmonary specific vasodilation, reduce the systemic exposure of the drug, and may be used as an alternative to oral sildenafil in the treatment of PAH. Thus, we prepared porous PLGA particles of sildenafil using a water-in-oil-in-water double emulsion solvent evaporation method with polyethyleneimine (PEI) as a porosigen and characterized the formulations for surface morphology, respirability, in-vitro drug release, and evaluated for in vivo absorption, alveolar macrophage uptake, and safety. PEI increased the particle porosity, drug entrapment, and produced drug release for 36h. Fluorescent particles showed reduced uptake by alveolar macrophages. The polymeric particles were safe to rat pulmonary arterial smooth muscle cell and to the lungs, as evidenced by the cytotoxicity assay and analyses of the injury markers in the bronchoalveolar lavage fluid, respectively. Intratracheally administered sildenafil particles elicited more pulmonary specific and sustained vasodilation in SUGEN-5416/hypoxia-induced PAH rats than oral, intravenous, or intratracheal plain sildenafil did, when administered at the same dose. Overall, true to the hypothesis, this study shows that inhaled PLGA particles of sildenafil can be administered, as a substitute for oral form of sildenafil, at a reduced dose and longer dosing interval.

Low-Molecular-Weight Heparin-Coated and Montelukast-Filled Inhalable Particles: A Dual-Drug Delivery System for Combination Therapy in Asthma.

Montelukast, a cysteinyl leukotriene type 1 receptor antagonist, exhibits secondary anti-inflammatory properties when used at higher concentrations. Low-molecular-weight heparin (LMWH) evokes pronounced anti-inflammatory effects by interrupting leukocyte adhesion and migration. We hypothesized that inhalable particles containing montelukast plus LMWH release both drugs in a sustained fashion and protect the lungs against allergen-induced inflammation. Large porous particles of montelukast and LMWH were prepared using a double-emulsion-solvent-evaporation method. Montelukast was first encapsulated in copolymer-based particles using polyethylenimine as a porosigen; the resulting particles were then coated with LMWH. The particles were evaluated for physicochemical properties, respirability, and release profiles. The anti-inflammatory effect of the optimized formulation was studied in ovalbumin-sensitized asthmatic Sprague Dawley rats. The optimized large porous particles had a diameter of 10.3 ± 0.7 µm, exhibited numerous surface indentations and pores, showed acceptable drug entrapment efficiency (66.8% ± 0.4% for montelukast; 91.7% ± 0.8% adsorption efficiency for LMWH), demonstrated biphasic release patterns, and escaped the uptake by the rat alveolar macrophages. The number of infiltrating inflammatory cells in asthmatic rat lungs, treated with dual-drug particles, was >74% fewer than in untreated asthmatic rat lungs. Similarly, the airway walls of asthmatic animals treated with dual-drug particles were 3-fold thinner than those of untreated asthmatic animals (p < 0.001). The optimized formulation protects lungs against methacholine-induced airway hyper-reactivity. Overall, this study demonstrates the feasibility of loading 2 drugs, montelukast and LMWH, into an inhalable particulate system and establishes that this novel combination therapy produces sustained drug release and elicits a robust anti-inflammatory response in the lungs.

Aerosolizable modified-release particles of montelukast improve retention and availability of the drug in the lungs.

Montelukast, a cysteinyl leukotriene receptor antagonist available as oral tablets, is used as a second-line therapy in asthma. In this study, we sought to enhance the availability of montelukast in the lungs by encapsulating the drug in poly (lactide-co-glycolic acid)-based (PLGA) respirable large porous particles. We determined the oral and lung specific availability of montelukast by assessing metabolic stability of the drug in the lung and liver homogenates, respectively. We similarly measured the oral and inhalational bioavailability by monitoring the pharmacokinetics and disposition of the drug in live animals. After preparing montelukast-loaded particles with various polymers, in the absence or presence of polyethylenimine (PEI-1), we characterized the particles for physical-chemical properties, entrapment efficiency, in vitro release, uptake by alveolar macrophages, deposition in the lungs, and safety after pulmonary administration. When incubated in lung or liver homogenates, the amount of intact drug in the lung homogenates was greater than that in the liver homogenates. Likewise, the extent of montelukast absorption via the lungs was greater than that via the oral route. Compared with smaller non-porous particles, large porous particles (PEI-1) were taken up by the alveolar macrophages at a lesser extent but deposited in the lungs at a greater extent. The levels of injury markers in the bronchoalveolar lavage fluid (BALF), collected from rat lungs treated with PEI-1, were no different from that in BALF collected from saline treated rats. Overall, the retention time and concentration of montelukast in the lungs can be increased by formulating the drug in large porous particles of PLGA.

Roflumilast N-Oxide in Combination with Formoterol Enhances the Antiinflammatory Effect of Dexamethasone in Airway Smooth Muscle Cells.

Roflumilast is an orally active phosphodiesterase 4 inhibitor approved for use in chronic obstructive pulmonary disease. Roflumilast N-oxide (RNO) is the active metabolite of roflumilast and has a demonstrated antiinflammatory impact in vivo and in vitro. To date, the effect of RNO on the synthetic function of airway smooth muscle (ASM) cells is unknown. We address this herein and investigate the effect of RNO on ß2-adrenoceptor-mediated, cAMP-dependent responses in ASM cells in vitro, and whether RNO enhances steroid-induced repression of inflammation. RNO (0.001-1,000 nM) alone had no effect on AMP production from ASM cells, and significant potentiation of the long-acting ß2-agonist formoterol-induced cAMP could only be achieved at the highest concentration of RNO tested (1,000 nM). At this concentration, RNO exerted a small, but not significantly different, potentiation of formoterol-induced expression of antiinflammatory mitogen-activated protein kinase phosphatase 1. Consequently, tumor necrosis factor-induced IL-8 secretion was unaffected by RNO in combination with formoterol. However, because there was the potential for phosphodiesterase 4 inhibitors and long-acting ß2-agonists to interact with corticosteroids to achieve superior antiinflammatory efficacy, we examined whether RNO, alone or in combination with formoterol, enhanced the antiinflammatory effect of dexamethasone by measuring the impact on IL-8 secretion. Although RNO alone did not significantly enhance the cytokine repression achieved with steroids, RNO in combination with formoterol significantly enhanced the antiinflammatory effect of dexamethasone in ASM cells. This was linked to increased mitogen-activated protein kinase phosphatase 1 expression in ASM cells, suggesting that a molecular mechanism is responsible for augmented antiinflammatory actions of combination therapeutic approaches that include RNO.

The phosphorylated form of FTY720 activates PP2A, represses inflammation and is devoid of S1P agonism in A549 lung epithelial cells.

Protein phosphatase 2A (PP2A) activity can be enhanced pharmacologically by PP2A-activating drugs (PADs). The sphingosine analog FTY720 is the best known PAD and we have shown that FTY720 represses production of pro-inflammatory cytokines responsible for respiratory disease pathogenesis. Whether its phosphorylated form, FTY720-P, also enhances PP2A activity independently of the sphingosine 1-phosphate (S1P) pathway was unknown. Herein, we show that FTY720-P enhances TNF-induced PP2A phosphatase activity and significantly represses TNF-induced interleukin 6 (IL-6) and IL-8 mRNA expression and protein secretion from A549 lung epithelial cells. Comparing FTY720 and FTY720-P with S1P, we show that unlike S1P, the sphingosine analogs do not induce cytokine production on their own. In fact, FTY720 and FTY720-P significantly repress S1P-induced IL-6 and IL-8 production. We then examined their impact on expression of cyclooxygenase 2 (COX-2) and resultant prostaglandin E2 (PGE2) production. S1P did not increase production of this pro-inflammatory enzyme because COX-2 mRNA gene expression is NF-κB-dependent, and unlike TNF, S1P did not activate NF-κB. However, TNF-induced COX-2 mRNA expression and PGE2 secretion is repressed by FTY720 and FTY720-P. Hence, FTY720-P enhances PP2A activity and that PADs can repress production of pro-inflammatory cytokines and enzymes in A549 lung epithelial cells in a manner devoid of S1P agonism.

TLR2 ligation induces corticosteroid insensitivity in A549 lung epithelial cells: Anti-inflammatory impact of PP2A activators.

Corticosteroids are effective anti-inflammatory therapies widely utilized in chronic respiratory diseases. But these medicines can lose their efficacy during respiratory infection resulting in disease exacerbation. Further in vitro research is required to understand how infection worsens lung function control in order to advance therapeutic options to treat infectious exacerbation in the future. In this study, we utilize a cellular model of bacterial exacerbation where we pretreat A549 lung epithelial cells with the synthetic bacterial lipoprotein Pam3CSK4 (a TLR2 ligand) to mimic bacterial infection and tumor necrosis factor α (TNFα) to simulate inflammation. Under these conditions, Pam3CSK4 induces corticosteroid insensitivity; demonstrated by substantially reduced ability of the corticosteroid dexamethasone to repress TNFα-induced interleukin 6 secretion. We then explored the molecular mechanism responsible and found that corticosteroid insensitivity induced by bacterial mimics was not due to altered translocation of the glucocorticoid receptor into the nucleus, nor an impact on the NF-κB pathway. Moreover, Pam3CSK4 did not affect corticosteroid-induced upregulation of anti-inflammatory MAPK deactivating phosphatase-MKP-1. However, Pam3CSK4 can induce oxidative stress and we show that a proportion of the MKP-1 produced in response to corticosteroid in the context of TLR2 ligation was rendered inactive by oxidation. Thus to combat inflammation in the context of bacterial exacerbation we sought to discover effective strategies that bypassed this road-block. We show for the first time that known (FTY720) and novel (theophylline) activators of the phosphatase PP2A can serve as non-steroidal anti-inflammatory alternatives and/or corticosteroid-sparing approaches in respiratory inflammation where corticosteroid insensitivity exists.

Microfluidics-based 3D cell culture models: Utility in novel drug discovery and delivery research.

The implementation of microfluidic devices within life sciences has furthered the possibilities of both academic and industrial applications such as rapid genome sequencing, predictive drug studies, and single cell manipulation. In contrast to the preferred two-dimensional cell-based screening, three-dimensional (3D) systems have more in vivo relevance as well as ability to perform as a predictive tool for the success or failure of a drug screening campaign. 3D cell culture has shown an adaptive response to the recent advancements in microfluidic technologies which has allowed better control over spheroid sizes and subsequent drug screening studies. In this review, we highlight the most significant developments in the field of microfluidic 3D culture over the past half-decade with a special focus on their benefits and challenges down the lane. With the newer technologies emerging, implementation of microfluidic 3D culture systems into the drug discovery pipeline is right around the bend.

Theophylline Represses IL-8 Secretion from Airway Smooth Muscle Cells Independently of Phosphodiesterase Inhibition. Novel Role as a Protein Phosphatase 2A Activator.

Theophylline is an old drug experiencing a renaissance owing to its beneficial antiinflammatory effects in chronic respiratory diseases, such as asthma and chronic obstructive pulmonary disease. Multiple modes of antiinflammatory action have been reported, including inhibition of the enzymes that degrade cAMP-phosphodiesterase (PDE). Using primary cultures of airway smooth muscle (ASM) cells, we recently revealed that PDE4 inhibitors can potentiate the antiinflammatory action of ß2-agonists by augmenting cAMP-dependent expression of the phosphatase that deactivates mitogen-activated protein kinase (MAPK)-MAPK phosphatase (MKP)-1. Therefore, the aim of this study was to address whether theophylline repressed cytokine production in a similar, PDE-dependent, MKP-1-mediated manner. Notably, theophylline did not potentiate cAMP release from ASM cells treated with the long-acting ß2-agonist formoterol. Moreover, theophylline (0.1-10 µM) did not increase formoterol-induced MKP-1 messenger RNA expression nor protein up-regulation, consistent with the lack of cAMP generation. However, theophylline (at 10 µM) was antiinflammatory and repressed secretion of the neutrophil chemoattractant cytokine IL-8, which is produced in response to TNF-α. Because theophylline's effects were independent of PDE4 inhibition or antiinflammatory MKP-1, we then wished to elucidate the novel mechanisms responsible. We investigated the impact of theophylline on protein phosphatase (PP) 2A, a master controller of multiple inflammatory signaling pathways, and show that theophylline increases TNF-α-induced PP2A activity in ASM cells. Confirmatory results were obtained in A549 lung epithelial cells. PP2A activators have beneficial effects in ex vivo and in vivo models of respiratory disease. Thus, our study is the first to link theophylline with PP2A activation as a novel mechanism to control respiratory inflammation.

Fasudil and SOD packaged in peptide-studded-liposomes: Properties, pharmacokinetics and ex-vivo targeting to isolated perfused rat lungs.

The present study investigated the feasibility of encapsulating two drugs, fasudil and superoxide dismutase (SOD), into liposomes for targeted and inhalational delivery to the pulmonary vasculature to treat pulmonary arterial hypertension (PAH). Nanosized liposomes were prepared by a thin-film formation and extrusion method, and the drugs were encapsulated by a modified freeze-thaw technique. The peptide CARSKNKDC (CAR), a pulmonary-specific targeting sequence, was conjugated on the surface of liposomes. Formulations were optimized for various physicochemical properties, tested for their ex-vivo and in-vivo drug absorption after intratracheal administration, and evaluated for short-term safety in healthy rats. The homogenous nanosized liposomes contained both SOD (~55% entrapment) and fasudil (~40% entrapment), and were stable at 4°C and after nebulization. Liposomes released the drugs in a controlled-release fashion. Compared with plain liposomes, CAR-liposomes increased the uptake by pulmonary endothelial and smooth muscle cells by ~2-fold. CAR-liposomes extended the biological half-lives of SOD and fasudil by ~3-fold. Ex-vivo studies demonstrated that CAR-liposomes were better retained in the lungs than plain liposomes. Bronchoalveolar lavage studies indicated the safety of peptide-equipped liposomes as pulmonary delivery carriers. Overall, this study demonstrates that CAR-liposomes may be used as inhalational carriers for SOD plus fasudil-based combination therapy for PAH.

Repression of breast cancer cell growth by proteasome inhibitors in vitro: impact of mitogen-activated protein kinase phosphatase 1.

Mitogen activated protein kinase phosphatase-1 (MKP-1) has emerged as an important protein mediating breast cancer oncogenesis and chemoresistance to cancer chemotherapies, especially proteasome inhibitors. In this in vitro study, we utilized the breast cancer epithelial cell lines MCF-7 and MDA-MB-231, in comparison to MCF-10A control cells, to examine the impact of MKP-1 on breast cancer cell growth and repression by proteasome inhibitors. We confirm that proteasome inhibitors MG-132 and bortezomib induce MKP-1 protein upregulation and we show that one of the ways in which bortezomib increases MKP-1 in breast cancer cells, in addition to inhibition of ubiquitin-proteasome system, is via upregulation of MKP-1 mRNA expression in p38 MAPK-mediated manner. Notably, these effects are specific to cancer cells, as bortezomib activated p38 MAPK and induced MKP-1 in MCF-7 and MDA-MB-231 breast cancer cells, but not in control cells (MCF-10A). We took a dual approach toward targeting MKP-1 to show that bortezomib-induced effects are enhanced. Firstly, treatment with the non-specific MKP-1 inhibitor triptolide reduces breast cancer cell growth and augments proteasome inhibitor-induced effects. Secondly, specific knock-down of MKP-1 with siRNA significantly repressed cell viability by reduced cyclin D1 expression, and enhanced repression of cancer cell growth by proteasome inhibitors. Taken together, these results indicate that removing the unwanted (MKP-1-inducing) effects of bortezomib significantly improves the efficacy of proteasome inhibition in breast cancer cells. Thus, future development of drugs targeting MKP-1 offer promise of combination therapies with reduced toxicity and enhanced cell death in breast cancer.

Particle engineering to enhance or lessen particle uptake by alveolar macrophages and to influence the therapeutic outcome.

The alveolar macrophages defend the lung against airborne pollutants and infectious microorganisms. Recent advances in the understanding of the role of macrophages in generation of immunological and inflammatory responses have established that alveolar macrophages could be used as targets for drug delivery. Enhanced uptake of particulate drug carriers by macrophages could be beneficial in pathological conditions such as tuberculosis and HIV where infectious microorganisms utilize macrophages as a safe haven and a vehicle to further infections. In contrary, to achieve prolonged residence time, extended drug release and in desired situations, increased systemic absorption, drug carrying particles that can avoid recognition and uptake by alveolar macrophages may prove to be significantly advantageous. Drug targeting to macrophages can achieve superior therapeutic efficacy for the treatment of medical conditions that involve tumorigenesis, inflammation and infections. Various particulate carriers containing therapeutic agents have been used to deliver drugs to the macrophages residing in the lung. Particulate systems have also been engineered to facilitate or avoid uptake by macrophages. But pathological conditions to be treated and drug delivery goals dictate the engineering approach for reducing or enhancing uptake by macrophages. In this review, we have summarized the influence of various physicochemical properties--composition, size, shape, pegylation and presence or absence of surface ligands--of particulate carriers on their uptake by macrophages. We have also described the macrophage biology and strategies that have been used to influence uptake and avoidance of particulate carriers by macrophages.

Inhibitors of Phosphodiesterase 4, but Not Phosphodiesterase 3, Increase ß2-Agonist-Induced Expression of Antiinflammatory Mitogen-Activated Protein Kinase Phosphatase 1 in Airway Smooth Muscle Cells.

ß2-agonists are principally used in asthma to provide bronchodilation; however, they also have antiinflammatory properties, due, in part, to their ability to up-regulate mitogen-activated protein kinase phosphatase (MKP) 1 in a cAMP-dependent manner. Phosphodiesterases (PDEs) are attractive targets for potentiating the antiinflammatory response. There are 11 subfamilies of PDE enzymes; among these, inhibition of PDE3 and PDE4 are the main targets for airway smooth muscle (ASM). PDE enzymes are important intracellular regulators that catalyze the breakdown of cyclic adenosine monophosphate (cAMP) and/or 3',5'-cyclic guanosine monophosphate to their inactive forms. Given that MKP-1 is cAMP dependent, and inhibition of PDE acts to increase ß2-agonist-induced cAMP, it is possible that the presence of PDE inhibitors may enhance ß2-adrenoceptor-mediated responses. We address this herein by comparing the ability of a panel of inhibitors against PDE3 (cilostamide, cilostazol, milrinone) or PDE4 (cilomilast, piclamilast, rolipram) to increase cAMP, MKP-1 mRNA expression, and protein up-regulation in ASM cells induced in response to the ß2-agonist formoterol. Our data show that inhibitors of PDE4, but not PDE3, increase ß2-agonist-induced cAMP and induce MKP-1 mRNA expression and protein up-regulation. When cAMP was increased, there was a concomitant increase in MKP-1 levels and significant inhibition of TNF-α-induced CXCL8 (IL-8). This result was consistent with all PDE4 inhibitors examined but not for the PDE3 inhibitors. These findings reinforce cAMP-dependent control of MKP-1 expression, and suggest that PDE4 is the predominant PDE isoform responsible for formoterol-induced cAMP breakdown in ASM cells. Our study is the first to demonstrate that PDE4 inhibitors augment antiinflammatory effects of ß2-agonists via increased MKP-1 expression in ASM cells.