Bispecific antibody shuttles targeting CD98hc mediate efficient and long-lived brain delivery of IgGs.

The inability of antibodies to penetrate the blood-brain barrier (BBB) is a key limitation to their use in diverse applications. One promising strategy is to deliver IgGs using a bispecific BBB shuttle, which involves fusing an IgG to a second affinity ligand that engages a cerebrovascular endothelial target and facilitates transport across the BBB. Nearly all prior efforts have focused on shuttles that target transferrin receptor (TfR-1) despite inherent delivery and safety challenges. Here, we report bispecific antibody shuttles that engage CD98hc, the heavy chain of the large neutral amino acid transporter (LAT1), and efficiently transport IgGs into the brain. Notably, CD98hc shuttles lead to much longer-lived brain retention of IgGs than TfR-1 shuttles while enabling more specific targeting due to limited CD98hc engagement in the brain parenchyma, which we demonstrate for IgGs that either agonize a neuronal receptor (TrkB) or target other endogenous cell-surface proteins on neurons and astrocytes.

Quantitative flow cytometric selection of tau conformational nanobodies specific for pathological aggregates.

Single-domain antibodies, also known as nanobodies, are broadly important for studying the structure and conformational states of several classes of proteins, including membrane proteins, enzymes, and amyloidogenic proteins. Conformational nanobodies specific for aggregated conformations of amyloidogenic proteins are particularly needed to better target and study aggregates associated with a growing class of associated diseases, especially neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. However, there are few reported nanobodies with both conformational and sequence specificity for amyloid aggregates, especially for large and complex proteins such as the tau protein associated with Alzheimer's disease, due to difficulties in selecting nanobodies that bind to complex aggregated proteins. Here, we report the selection of conformational nanobodies that selectively recognize aggregated (fibrillar) tau relative to soluble (monomeric) tau. Notably, we demonstrate that these nanobodies can be directly isolated from immune libraries using quantitative flow cytometric sorting of yeast-displayed libraries against tau aggregates conjugated to quantum dots, and this process eliminates the need for secondary nanobody screening. The isolated nanobodies demonstrate conformational specificity for tau aggregates in brain samples from both a transgenic mouse model and human tauopathies. We expect that our facile approach will be broadly useful for isolating conformational nanobodies against diverse amyloid aggregates and other complex antigens.

Bispecific antibody shuttles targeting CD98hc mediate efficient and long-lived brain delivery of IgGs.

The inability of antibodies and other biologics to penetrate the blood-brain barrier (BBB) is a key limitation to their use in diagnostic, imaging, and therapeutic applications. One promising strategy is to deliver IgGs using a bispecific BBB shuttle, which involves fusing an IgG with a second affinity ligand that engages a cerebrovascular endothelial target and facilitates transport across the BBB. Nearly all prior efforts have focused on the transferrin receptor (TfR-1) as the prototypical endothelial target despite inherent delivery and safety challenges. Here we report bispecific antibody shuttles that engage CD98hc (also known as 4F2 and SLC3A2), the heavy chain of the large neutral amino acid transporter (LAT1), and efficiently transport IgGs into the brain parenchyma. Notably, CD98hc shuttles lead to much longer-lived brain retention of IgGs than TfR-1 shuttles while enabling more specific brain targeting due to limited CD98hc engagement in the brain parenchyma. We demonstrate the broad utility of the CD98hc shuttles by reformatting three existing IgGs as CD98hc bispecific shuttles and delivering them to the mouse brain parenchyma that either agonize a neuronal receptor (TrkB) or target other endogenous antigens on specific types of brain cells (neurons and astrocytes).

Cross-Seeding Controls Aß Fibril Populations and Resulting Functions.

Amyloid peptides nucleate from monomers to aggregate into fibrils through primary nucleation. Pre-existing fibrils can then act as seeds for additional monomers to fibrillize through secondary nucleation. Both nucleation processes occur simultaneously, yielding a distribution of fibril polymorphs that can generate a spectrum of neurodegenerative effects. Understanding the mechanisms driving polymorph structural distribution during both nucleation processes is important for uncovering fibril structure-function relationships, as well as for creating polymorph distributions in vitro that better match fibril structures found in vivo. Here, we explore how cross-seeding wild-type (WT) Aß1-40 with Aß1-40 mutants E22G (Arctic) and E22Δ (Osaka), as well as with WT Aß1-42, affects the distribution of fibril structural polymorphs and how changes in structural distribution impact toxicity. Transmission electron microscopy analysis revealed that fibril seeds derived from mutants of Aß1-40 imparted their structure to WT Aß1-40 monomers during secondary nucleation, but WT Aß1-40 fibril seeds do not affect the structure of fibrils assembled from mutant Aß1-40 monomers, despite the kinetic data indicating accelerated aggregation when cross-seeding of any combination of mutants. Additionally, WT Aß1-40 fibrils seeded with mutant fibrils produced similar structural distributions to the mutant seeds with similar cytotoxicity profiles. This indicates that mutant fibril seeds not only impart their structure to growing WT Aß1-40 aggregates but also impart cytotoxic properties. Our findings establish a relationship between the fibril structure and the phenotype on a polymorph population level and that these properties can be passed on through secondary nucleation to the succeeding generations of fibrils.

Functionalized Mesoporous Silicas Direct Structural Polymorphism of Amyloid-ß Fibrils.

The aggregation of amyloid-ß (Aß) is associated with the onset of Alzheimer's disease (AD) and involves a complex kinetic pathway as monomers self-assemble into fibrils. A central feature of amyloid fibrils is the existence of multiple structural polymorphs, which complicates the development of disease-relevant structure-function relationships. Developing these relationships requires new methods to control fibril structure. In this work, we evaluated the effect that mesoporous silicas (SBA-15) functionalized with hydrophobic (SBA-PFDTS) and hydrophilic groups (SBA-PEG) have on the aggregation kinetics and resulting structure of Aß1-40 fibrils. The hydrophilic SBA-PEG had little effect on amyloid kinetics, while as-synthesized and hydrophobic SBA-PFDTS accelerated aggregation kinetics. Subsequently, we quantified the relative population of fibril structures formed in the presence of each material using electron microscopy. Fibrils formed from Aß1-40 exposed to SBA-PEG were structurally similar to control fibrils. In contrast, Aß1-40 incubated with SBA-15 or SBA-PFDTS formed fibrils with shorter crossover distances that were more structurally representative of fibrils found in AD patient derived samples. Overall, our results suggest that mesoporous silicas and other exogenous materials are promising scaffolds for the de novo production of specific fibril polymorphs of Aß1-40 and other amyloidogenic proteins.

Influence of Zeolites on Amyloid-ß Aggregation.

Aggregation of Aß plays a key role in the progression of Alzheimer's disease. Unfortunately, the Aß aggregation mechanism is complex, leading to a structurally diverse population of oligomers and amyloid fibrils. Heterogeneous interfaces have been shown to influence the rate of fibrilization and may be useful tools to bias amyloid formation toward specific structures. In order to better understand how exogenous materials influence Aß aggregation, Aß1-40 was exposed to zeolite Y containing different metal cations, including Na+, Mg2+, Fe3+, Zn2+, and Cu2+. NaY, MgY, and FeY, all accelerated the kinetics of fibrilization by increasing the primary nucleation rate, while CuY and ZnY inhibited fibrilization. These kinetic effects were supported through binding affinity measurements, in which ZnY and CuY showed higher association constants than the other zeolites. In addition to influencing the kinetics of fibrilization, the zeolites also affected the intermediate structures along the pathway. Western blots confirmed that Aß1-40 was arrested at the oligomeric stage in the presence of ZnY and CuY, while continuing to the fibrillary state in the presence of other zeolites. Seeding studies showed that NaY and FeY form on-pathway oligomers, while ZnY formed off-pathway oligomers. Overall, our results show that zeolites can impact the aggregation and speciation of amyloids.

Randomized trial of preinduction cervical ripening: misoprostol vs oxytocin.

OBJECTIVE: The purpose of this study was to compare the vaginal delivery rate in women who undergo labor induction with preinduction misoprostol or oxytocin alone. STUDY DESIGN: Women with singleton pregnancies and Bishop scores <5 with labor induction at > or = 24 weeks of gestation were eligible; they were assigned randomly to oxytocin alone or preinduction cervical ripening with misoprostol. Labor characteristics, maternal complications, and neonatal outcomes were analyzed. RESULTS: One hundred sixty-three women received oxytocin, and 164 women received misoprostol. Maternal demographics, pretreatment Bishop scores, and labor analgesia were similar between groups. Vaginal delivery rates were also similar: 87% (n = 141) for oxytocin and 81% (n = 133) for misoprostol. Mean time from treatment to delivery was shorter for the oxytocin group, compared with the misoprostol group (13.1 vs 16.3 hours; P = .005). There was no difference in maternal complications or neonatal outcomes between groups. CONCLUSION: Preinduction cervical ripening with misoprostol did not improve the vaginal delivery rate and resulted in longer intervals to active labor and delivery. Preinduction cervical ripening with misoprostol may not be necessary.

Dichorionic twins discordant for thanatophoric dysplasia managed with selective reduction at 20 weeks' gestation: a case report.

BACKGROUND: Thanatophoric dysplasia (TD) is a rare and lethal form of skeletal disorder. A MEDLINE search for 1965-2003 yielded only 3 reports of multiple pregnancies discordant for TD. This is the first case report of selective twin reduction for this diagnosis. CASE: A young woman was seen in consultation at 20 weeks' gestation. Ultrasound examination revealed a twin pregnancy, with ultrasound markers consistent with thanatophoric dysplasia, type II, in twin A. A thick dividing membrane and separated placentas were noted. After counseling, the patient opted for selective termination of twin A. Termination was performed by intracardiac injection of potassium chloride. The pregnancy continued uneventfully until 33 weeks, when spontaneous labor resulted in vaginal delivery of a vigorous female infant, and a mummified, macerated fetus. CONCLUSION: Selective termination for discordant lethal anomalies can be safely performed when the presence of the anomalous twin increases the risk of a poor perinatal outcome for the apparently normal cotwin.

High glucose levels down-regulate glucose transporter expression that correlates with increased oxidative stress in placental trophoblast cells in vitro.

OBJECTIVE: To study glucose transporter expression and oxidative stress in placental trophoblasts under hyperglycemic conditions in vitro. METHODS: Trophoblasts were isolated from term normal human placentas and incubated with Dulbecco's modified eagle medium containing 1000, 2500, and 4500 mg/L glucose for 3 days. At the end of incubation, culture medium was collected. Trophoblast RNA was extracted and mRNA expression of glucose transporters was determined by RNase protection assay. Messenger RNA expression for copper-zinc-superoxide dismutase (CuZn-SOD) was determined by real-time polymerase chain reaction. Lipid peroxide production was determined by measuring malondialdehyde concentration in the culture supernatant. Protein expression of sodium-glucose transporter 2 (SGLT-2) was determined by Western blot analysis. RESULTS: Messenger RNA expression for glucose transporter 1 (GLUT1) and SGLT-2 were reduced in trophoblast cells incubated with 4500 mg/L glucose compared with those incubated with 1000 and 2000 mg/L glucose. mRNA expression of CuZn-SOD was also decreased in trophoblasts incubated with 4500 mg/L glucose. Malondialdehyde production was significantly increased by trophoblasts incubated with 4500 mg/L glucose compared with those by trophoblasts incubated with 1000 and 2000 mg/L glucose (4.69 +/- 0.60 versus 2.10 +/- 0.29 and 2.89 +/- 0.47 nmol/mg protein; P < .01, respectively). CONCLUSIONS: Down-regulation of gene expression of glucose transporters correlates with increased lipid peroxide production and decreased superoxide dismutase expression in placental trophoblasts cultured under hyperglycemic conditions.

Increased endothelial monolayer permeability is induced by serum from women with preeclampsia but not by serum from women with normal pregnancy or that are not pregnant.

OBJECTIVE: To determine if endothelial monolayer permeability could be altered by serum from preeclampsia (PE). METHODS: Confluent normal endothelial cells (ECs) were incubated with 20% serum from nonpregnant females, normal and PE pregnancies or combined with antioxidant superoxide dismutase (SOD) for 8 hr. Confluent PE ECs were incubated with 20% serum from normal pregnancies. EC barrier function of monolayer permeability was accessed by measuring EC electrical resistance (ER) and the leakage of horseradish peroxidase (HRP) passing through EC filters. Plasma concentrations of IL-8 and lipid peroxides by MDA were also measured. We determined 1) if serum from PE could affect EC permeable function; 2) if antioxidant and serum from normal pregnancies could preserve PE EC barrier function; 3) if lipid peroxides and cytokine IL-8 were increased in PE blood samples. Data are presented as mean+/-SE. ANOVA was used for statistical analysis. A p level less than 0.05 was considered statistically different. RESULTS: 1) ER was significantly decreased and HRP passage was significantly increased in ECs incubated with serum from PE compared to serum from non-pregnant and normal pregnant females (ER: 36.30+/-2.60 vs. 51.30+/-4.00 and 53.90+/-5.80 Omega x cm2, p<0.01; HRP: 0.100+/-0.020 vs. 0.014+/-0.002 and 0.022+/-0.007 DeltaOD470 nm, p<0.01, respectively). 2) ER was improved in PE ECs incubated with serum from normal pregnancies compared to controls, 52.28+/-3.13 vs. 34.50+/-3.80 Omega x cm2, p<0.01. 3) SOD attenuated decreased EC ER induced by PE serum, 55.58+/-3.61 Omega x cm2 (SOD+PE serum) vs. 42.34+/-3.24 (control) and 35.46+/-2.44 (PE serum), p<0.01, respectively. 4) Both MDA and IL-8 concentrations were higher in plasma or serum samples from PE than those in samples from nonpregnancies and normal pregnancies, MDA: 28.65+/-1.45 vs. 22.40+/-1.47 and 25.53+/-0.89 micromol/mL, p<0.01; IL-8: 5.35+/-1.08 vs. 1.69+/-0.47 and 2.28+/-0.73 pg/mL, p<0.05, respectively. Conclusions. 1) Sera from PE but not from nonpregnant women or normal pregnancies increase EC monolayer permeability. 2) Increased lipid peroxides and IL-8 are candidates altering EC barrier function. 3) Antioxidant SOD preserves increased EC monolayer permeability induced by PE serum, suggesting that EC oxidative stress may be associated with altered EC barrier function in preeclampsia.

Antioxidant superoxide dismutase attenuates increased endothelial permeability induced by platelet-activating factor.

To study the protective effects of the antioxidant superoxide dismutase (SOD) against platelet-activating factor (PAF)-induced endothelial permeability. Endothelial cells (ECs) were isolated from human umbilical veins from normal pregnancies. The first passage (P1) ECs were grown in polycarbonate transwell filters. Confluent ECs were incubated with PAF at concentrations of 2, 5, and 10 microgram/mL for 2 hours or pretreated with superoxide dismutase. Endothelial monolayer permeability was then measured by EC electrical resistance or by the leakage of horseradish peroxide (HRP) passing through filters. Endothelial junctional protein distribution and expression of VE-cadherin and occludin were determined by fluorescent staining of endothelial monolayer and by Western blot analysis. mRNA expressions for VE-cadherin and occludin were determined by reverse transcriptase-polymerase chain reaction. Data are expressed as Omega. cm(2) for electrical resistance and DeltaOD 470 nm for HRP assay and presented as mean +/- standard error of the mean. Analysis of variance was used for statistical analysis. A P value less than.05 was considered statistically significant. Endothelial cell electrical resistance was decreased and HRP leakage was increased in ECs treated with PAF. Intercellular gaps were formed at cell contact regions in ECs treated with PAF, as evaluated by staining of junctional protein VE-cadherin and occludin. The functional changes of the EC barrier and the formation of intercellular gaps induced by PAF were concentration dependent, which could be partially attenuated by pretreatment of ECs with SOD. Total cellular junctional protein expression and mRNA expression of VE-cadherin and occludin were not affected by PAF. Increased EC monolayer permeability induced by platelet-activating factor is associated with disorganization of EC junctional protein distribution of VE-cadherin and occludin. Superoxide dismutase partially attenuated the PAF-induced increased endothelial monolayer permeability, which suggests that oxidative stress might be involved in the process of PAF-induced disturbances of endothelial barrier function.

Expression of thrombin receptors in endothelial cells and neutrophils from normal and preeclamptic pregnancies.

Thrombin receptors, i.e. proteinase-activated receptors (PARs), are expressed in endothelial cells (ECs) and neutrophils and directly affect platelet function and thrombosis. Although endothelial dysfunction and neutrophil activation have been demonstrated in women with preeclampsia (PE), the expression and regulation of PARs have not been defined in PE. In this study, we measured the expression of PARs in ECs and in neutrophils derived from normal and preeclamptic pregnancies. We also examined the effects of placental factors on PAR expression in these cells in vitro. ECs were isolated from umbilical cords (human umbilical vein ECs) from normal and preeclamptic pregnancies. Neutrophils were isolated from blood obtained from nonpregnant, uncomplicated pregnant, and preeclamptic women. Total RNA was extracted from the first-passage (P1) ECs (normal and PE) and from normal P1 ECs incubated with conditioned media derived from normal and preeclamptic placental cultures. The mRNA expression of thrombin receptor (PAR1), PAR2, and PAR3 was measured by ribonuclease protective assay. The expression of glyceraldehyde 3-phosphate dehydrogenase was used as an internal control for each sample. We found that: 1) PAR1 expression was enhanced in ECs from PE, compared with ECs from normal pregnancies; 2) PAR2 expression was expressed in PE ECs but not in normal ECs; 3) neutrophils from nonpregnant women, normal, and preeclamptic pregnancies expressed PAR2, whereas only neutrophils from normal and preeclamptic pregnancies expressed PAR1; and 4) factors released from preeclamptic placenta up-regulated PAR1 and PAR2 expression in ECs but not in neutrophils. We conclude that mRNA expression of PAR1 and PAR2 is increased in ECs derived from preeclamptic pregnancies. Up-regulation of thrombin receptor expression in neutrophils may be a unique phenomenon during pregnancy but not apparently unique to PE. Factors released from the placenta are likely candidates in regulating PAR expression in ECs and may contribute to the platelet activation and vascular endothelial dysfunction in PE.

Effects of nicotine on intercellular adhesion molecule expression in endothelial cells and integrin expression in neutrophils in vitro.

OBJECTIVE: We previously reported that nicotine decreases leukocyte adhesion to uterine vascular endothelial cells in vivo under ischemic conditions in pregnant rabbits. To further investigate the mechanism of decreased leukocyte-endothelial adhesion by nicotine exposure, the effect of nicotine on endothelial cell intercellular adhesion molecule expression and neutrophil integrin expression of CD62L, CD11a, and CD11b were examined. STUDY DESIGN: Endothelial cells were isolated from human umbilical cord veins from normal pregnancies in nonsmoking women immediately after delivery. Neutrophils were isolated from healthy nonpregnant and nonsmoking female volunteers. First passage of endothelial cells and fresh isolated neutrophils were exposed to nicotine at different concentrations. Surface adhesion molecule expression of intercellular adhesion molecule on endothelial cells was determined by colorimetric assay. Neutrophil integrin expressions for CD62L, CD11a, and CD11b were determined by flow cytometry. Messenger RNA expression for intercellular adhesion molecule in endothelial cells was examined by reverse transcription-polymerase chain reaction. RESULTS: Nicotine at a lower concentration of 0.01 micromol/L had no effect on endothelial cell surface intercellular adhesion molecule expression compared with controls (P =.614). Nicotine at a higher concentration of 10 micromol/L completely inhibited endothelial cell surface intercellular adhesion molecule-1 expression(P <.0001). At concentrations between 0.10 and 10 micromol/L, nicotine inhibited intercellular adhesion molecule expression in a dose-dependent manner. Messenger RNA expression of intercellular adhesion molecule in endothelial cells was not changed after exposure to nicotine. Decreased integrin expressions of CD62L, CD11a, and CD11b were observed on neutrophils after exposure to nicotine. CONCLUSION: Nicotine exerts inhibitory effects on both endothelial cell surface intercellular adhesion molecule expression and neutrophil integrin expressions of CD62L, CD11a, and CD11b in vitro. These in vitro effects of nicotine may relate to the clinical observation of reduced incidence of preeclampsia in women that smoke.