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1.  The contribution of cell surface FcRn in monoclonal antibody serum uptake from the intestine in suckling rat pups 
The neonatal Fc receptor (FcRn) in intestinal epithelium is the primary mechanism for transfer of maternal immunoglobulin G (IgG) from suckled milk to serum; but the factors contributing to the rapid uptake of IgG are poorly understood. These studies help to determine the contribution of cell surface FcRn in IgG uptake in 2-week-old rat pups by varying local pH and binding conditions. Variants of a human wild-type (WT) IgG monoclonal antibody (mAb WT) were assessed for binding affinity (KD) to rat (r)FcRn at pH 6.0 and subsequent off-rate at pH 7.4 (1/s) by surface plasmon resonance. Selected mAbs were administered intra-intestinally in isoflurane-anesthetized 2-week rat pups. Full length mAb in serum was quantified by immunoassay, (r)FcRn mRNA expression by reverse transcription polymerase chain reaction, and mAb epithelial localization was visualized by immunohistochemistry. After duodenal administration, serum levels of mAb variants correlated with their rFcRn off-rate at pH 7.4, but not their affinity at pH 6.0. The greatest serum levels of IgG were measured when mAb was administered in the duodenum where rFcRn mRNA expression is greatest, and was increased further by duodenal administration in pH 6.0 buffer. More intense human IgG immunostaining was detected in epithelium than the same variant administered at higher pH. These data suggest an increased contribution for cell surface receptor. We conclude that, in the neonate duodenum, receptor off-rates are as important as affinities for FcRn mediated uptake, and cell surface binding of IgG to rFcRn plays contributes to IgG uptake alongside pinocytosis; both of which responsible for increased IgG uptake.
doi:10.3389/fphar.2014.00225
PMCID: PMC4188031  PMID: 25339905
FcRn; IgG; uptake; bioavailability; cell surface receptor
2.  In vitro and in vivo pharmacological profile of PL-3994, a novel cyclic peptide (Hept-cyclo(Cys-His-Phe-d-Ala-Gly-Arg-d-Nle-Asp-Arg-Ile-Ser-Cys)-Tyr-[Arg mimetic]-NH2) natriuretic peptide receptor-A agonist that is resistant to neutral endopeptidase and acts as a bronchodilator 
The pharmacological and airways relaxant profiles of PL-3994 (Hept-cyclo(Cys-His-Phe-d-Ala-Gly-Arg-dNle-Asp-Arg-Ile-Ser-Cys)-Tyr-[Arg mimetic]-NH2), a novel natriuretic peptide receptor-A (NPR-A) agonist, were evaluated. PL-3994, a full agonist, has high affinity for recombinant human (h), dog, or rat NPR-As (Kis of 1, 41, and 10 nm, respectively), and produced concentration-dependent cGMP generation in human, dog and rat NPR-As (respective EC50s of 2, 3 and 14 nm). PL-3994 has a Ki of 7 nm for hNPR-C but was without effect on cGMP generation in hNPR-B. PL-3994 (1 µm) was without significant effect against 75 diverse molecular targets. PL-3994 or BNP, a natural NPR ligand, produced concentration-dependent relaxation of pre-contracted guinea-pig trachea (IC50s of 42.7 and 10.7 nm, respectively). PL-3994, and also BNP, (0.1 nm–100 µm) elicited a potent, concentration-dependent but small relaxation of pre-contracted human precision-cut lung slices (hPCLS). Intratracheal PL-3994 (1–1000 µg/kg) produced a dose-dependent inhibition of the bronchoconstrictor response evoked by aerosolized methacholine, but was without significant effect on cardiovascular parameters. PL-3994 was resistant to degradation by human neutral endopeptidase (hNEP) (92% remaining after 2 h), whereas the natural ligands, ANP and CNP, were rapidly metabolized (≤1% remaining after 2 h). PL-3994 is a potent, selective NPR agonist, resistant to NEP, with relaxant effects in guinea-pig and human airway smooth muscle systems. PL-3994 has the profile predictive of longer clinical bronchodilator activity than observed previously with ANP, and suggests its potential utility in the treatment of asthma, in addition to being a useful research tool to evaluate NPR biology.
doi:10.1016/j.pupt.2012.11.001
PMCID: PMC4070431  PMID: 23154072
PL-3994; Natriuretic peptide receptors; Atrial natriuretic peptide; Brain natriuretic peptide; Neutral endopeptidase sensitivity; Bronchodilator
3.  C-027 Inhibits IgE-mediated passive sensitization bronchoconstriction and acts as a histamine and serotonin antagonist in human airways 
Atopic asthma is poorly controlled by current therapies. Newer therapies and novel antihistamines are, therefore, required to treat patients whose atopic asthma is not controlled. For the first time, C-027 is shown to antagonize histamine, IgE-mediated and serotonin-induced contraction in human airways and vessels. Human precision-cut lung slices (PCLS, 250 µm thick), containing an airway or blood vessel, were pretreated with either C-027 (2 hours) or with vehicle alone and were contracted with histamine or serotonin. Known antihistamine was used as a comparator in antihistamine studies. Also, human airways were contracted via IgE passive sensitization in the presence or absence of C-027 or fexofenadine. Affinity of C-027 toward human G-protein coupled receptors was also determined, as well as the drug's biodistribution in murine model. C-027 was shown to have the highest affinity toward human histamine and serotonin receptors. Subsequently, C-027 was shown to antagonize histamine- and serotonin-induced airway and vascular smooth muscle contraction, respectively, and histamine-released bronchocontraction mediated by IgE passive sensitization in human small airways. C-027 also inhibited histamine-mediated single-cell calcium ion release. Low levels of C-027 were found in murine brain tissue. Collectively, these data suggest that C-027 markedly inhibits IgE-induced bronchoconstriction and antagonizes histamine and serotonin-contraction with little biodistribution in the brain. The compound may offer a future therapy for allergen-induced airway hyperresponsiveness in patients with asthma.
doi:10.2500/aap.2011.32.3460
PMCID: PMC3968313  PMID: 22195688
Airway smooth muscle; allergy; antagonist; anti-histamine; anti-serotonic; asthma; IgE mediated; novel compound; PCLS; reverse agonist
4.  Human and Non-Human Primate Intestinal FcRn Expression and Immunoglobulin G Transcytosis 
Pharmaceutical Research  2013;31(4):908-922.
ABSTRACT
Purpose
To evaluate transcytosis of immunoglobulin G (IgG) by the neonatal Fc receptor (FcRn) in adult primate intestine to determine whether this is a means for oral delivery of monoclonal antibodies (mAbs).
Methods
Relative regional expression of FcRn and localization in human intestinal mucosa by RT-PCR, ELISA & immunohistochemistry. Transcytosis of full-length mAbs (sandwich ELISA-based detection) across human intestinal segments mounted in Ussing-type chambers, human intestinal (caco-2) cell monolayers grown in transwells, and serum levels after regional intestinal delivery in isoflurane-anesthetized cynomolgus monkeys.
Results
In human intestine, there was an increasing proximal-distal gradient of mucosal FcRn mRNA and protein expression. In cynomolgus, serum mAb levels were greater after ileum-proximal colon infusion than after administration to stomach or proximal small intestine (1–5 mg/kg). Serum levels of wild-type mAb dosed into ileum/proximal colon (2 mg/kg) were 124 ± 104 ng/ml (n = 3) compared to 48 ± 48 ng/ml (n = 2) after a non-FcRn binding variant. In vitro, mAb transcytosis in polarized caco-2 cell monolayers and was not enhanced by increased apical cell surface IgG binding to FcRn. An unexpected finding in primate small intestine, was intense FcRn expression in enteroendocrine cells (chromagranin A, GLP-1 and GLP-2 containing).
Conclusions
In adult primates, FcRn is expressed more highly in distal intestinal epithelial cells. However, mAb delivery to that region results in low serum levels, in part because apical surface FcRn binding does not influence mAb transcytosis. High FcRn expression in enteroendocrine cells could provide a novel means to target mAbs for metabolic diseases after systemic administration.
doi:10.1007/s11095-013-1212-3
PMCID: PMC3953555  PMID: 24072267
drug delivery; epithelial cell; Fc receptor; monoclonal antibody; oral bioavailability
5.  Regulator of G-Protein Signaling–5 Inhibits Bronchial Smooth Muscle Contraction in Severe Asthma 
Severe asthma is associated with fixed airway obstruction attributable to inflammation, copious luminal mucus, and increased airway smooth muscle (ASM) mass. Paradoxically, studies demonstrated that the hypertrophic and hyperplastic ASM characteristic of severe asthma has reduced contractile capacity. We compared the G-protein–coupled receptor (GPCR)–induced Ca2+ mobilization and expression of GPCRs and signaling proteins related to procontractile signaling in ASM derived postmortem from subjects who died of nonrespiratory causes, with cells from subjects who died of asthma. Despite the increased or comparable expression of contraction-promoting GPCRs (bradykinin B2 or histamine H1 and protease-activated receptor 1, respectively) in asthmatic ASM cells relative to cells from healthy donors, asthmatic ASM cells exhibited reduced histamine-induced Ca2+ mobilization and comparable responses to bradykinin and thrombin, suggesting a postreceptor signaling defect. Accordingly, the expression of regulator of G-protein signaling–5 (RGS5), an inhibitor of ASM contraction, was increased in cultured, asthmatic ASM cells and in bronchial smooth muscle bundles of both human subjects with asthma and allergen-challenged mice, relative to those of healthy human subjects or naive mice. The overexpression of RGS5 impaired the release of Ca2+ to thrombin, histamine, and carbachol, and reduced the contraction of precision-cut lung slices to carbachol. These results suggest that increased RGS5 expression contributes to decreased myocyte shortening in severe and fatal asthma.
doi:10.1165/rcmb.2011-0110OC
PMCID: PMC3380291  PMID: 22281988
asthma; bronchial smooth muscle; signal transduction; G-protein–coupled receptors
6.  An RGS4-Mediated Phenotypic Switch of Bronchial Smooth Muscle Cells Promotes Fixed Airway Obstruction in Asthma 
PLoS ONE  2012;7(1):e28504.
In severe asthma, bronchodilator- and steroid-insensitive airflow obstruction develops through unknown mechanisms characterized by increased lung airway smooth muscle (ASM) mass and stiffness. We explored the role of a Regulator of G-protein Signaling protein (RGS4) in the ASM hyperplasia and reduced contractile capacity characteristic of advanced asthma. Using immunocytochemical staining, ASM expression of RGS4 was determined in endobronchial biopsies from healthy subjects and those from subjects with mild, moderate and severe asthma. Cell proliferation assays, agonist-induced calcium mobilization and bronchoconstriction were determined in cultured human ASM cells and in human precision cut lung slices. Using gain- and loss-of-function approaches, the precise role of RGS proteins was determined in stimulating human ASM proliferation and inhibiting bronchoconstriction. RGS4 expression was restricted to a subpopulation of ASM and was specifically upregulated by mitogens, which induced a hyperproliferative and hypocontractile ASM phenotype similar to that observed in recalcitrant asthma. RGS4 expression was markedly increased in bronchial smooth muscle of patients with severe asthma, and expression correlated significantly with reduced pulmonary function. Whereas RGS4 inhibited G protein-coupled receptor (GPCR)-mediated bronchoconstriction, unexpectedly RGS4 was required for PDGF-induced proliferation and sustained activation of PI3K, a mitogenic signaling molecule that regulates ASM proliferation. These studies indicate that increased RGS4 expression promotes a phenotypic switch of ASM, evoking irreversible airway obstruction in subjects with severe asthma.
doi:10.1371/journal.pone.0028504
PMCID: PMC3257220  PMID: 22253691
7.  Expression and activation of the oxytocin receptor in airway smooth muscle cells: Regulation by TNFα and IL-13 
Respiratory Research  2010;11(1):104.
Background
During pregnancy asthma may remain stable, improve or worsen. The factors underlying the deleterious effect of pregnancy on asthma remain unknown. Oxytocin is a neurohypophyseal protein that regulates a number of central and peripheral responses such as uterine contractions and milk ejection. Additional evidence suggests that oxytocin regulates inflammatory processes in other tissues given the ubiquitous expression of the oxytocin receptor. The purpose of this study was to define the role of oxytocin in modulating human airway smooth muscle (HASMCs) function in the presence and absence of IL-13 and TNFα, cytokines known to be important in asthma.
Method
Expression of oxytocin receptor in cultured HASMCs was performed by real time PCR and flow cytomery assays. Responses to oxytocin was assessed by fluorimetry to detect calcium signals while isolated tracheal rings and precision cut lung slices (PCLS) were used to measure contractile responses. Finally, ELISA was used to compare oxytocin levels in the bronchoalveloar lavage (BAL) samples from healthy subjects and those with asthma.
Results
PCR analysis demonstrates that OXTR is expressed in HASMCs under basal conditions and that both interleukin (IL)-13 and tumor necrosis factor (TNFα) stimulate a time-dependent increase in OXTR expression at 6 and 18 hr. Additionally, oxytocin increases cytosolic calcium levels in fura-2-loaded HASMCs that were enhanced in cells treated for 24 hr with IL-13. Interestingly, TNFα had little effect on oxytocin-induced calcium response despite increasing receptor expression. Using isolated murine tracheal rings and PCLS, oxytocin also promoted force generation and airway narrowing. Further, oxytocin levels are detectable in bronchoalveolar lavage (BAL) fluid derived from healthy subjects as well as from those with asthma.
Conclusion
Taken together, we show that cytokines modulate the expression of functional oxytocin receptors in HASMCs suggesting a potential role for inflammation-induced changes in oxytocin receptor signaling in the regulation of airway hyper-responsiveness in asthma.
doi:10.1186/1465-9921-11-104
PMCID: PMC2922094  PMID: 20670427
8.  20-HETE Mediates Ozone-Induced, Neutrophil-Independent Airway Hyper-Responsiveness in Mice 
PLoS ONE  2010;5(4):e10235.
Background
Ozone, a pollutant known to induce airway hyper-responsiveness (AHR), increases morbidity and mortality in patients with obstructive airway diseases and asthma. We postulate oxidized lipids mediate in vivo ozone-induced AHR in murine airways.
Methodology/Principal Findings
Male BALB/c mice were exposed to ozone (3 or 6 ppm) or filtered air (controls) for 2 h. Precision cut lung slices (PCLS; 250 µm thickness) containing an intrapulmonary airway (∼0.01 mm2 lumen area) were prepared immediately after exposure or 16 h later. After 24 h, airways were contracted to carbachol (CCh). Log EC50 and Emax values were then calculated by measuring the airway lumen area with respect to baseline. In parallel studies, dexamethasone (2.5 mg/kg), or 1-aminobenzotriazol (ABT) (50 mg/kg) were given intraperitoneal injection to naïve mice 18 h prior to ozone exposure. Indomethacin (10 mg/kg) was administered 2 h prior. Cell counts, cytokine levels and liquid chromatography-mass spectrometry (LC-MS) for lipid analysis were assessed in bronchoalveolar lavage (BAL) fluid from ozone exposed and control mice. Ozone acutely induced AHR to CCh. Dexamethasone or indomethacin had little effect on the ozone-induced AHR; while, ABT, a cytochrome P450 inhibitor, markedly attenuated airway sensitivity. BAL fluid from ozone exposed animals, which did not contain an increase in neutrophils or interleukin (IL)-6 levels, increased airway sensitivity following in vitro incubation with a naïve PCLS. In parallel, significant increases in oxidized lipids were also identified using LC-MS with increases of 20-HETE that were decreased following ABT treatment.
Conclusions/Significance
These data show that ozone acutely induces AHR to CCh independent of inflammation and is insensitive to steroid treatment or cyclooxygenase (COX) inhibition. BAL fluid from ozone exposed mice mimicked the effects of in vivo ozone exposure that were associated with marked increases in oxidized lipids. 20-HETE plays a pivotal role in mediating acute ozone-induced AHR.
doi:10.1371/journal.pone.0010235
PMCID: PMC2857875  PMID: 20422032

Résultats 1-8 (8)