Curcumin and anthocyanin inhibit pepsin-mediated cell damage and carcinogenic changes in airway epithelial cells.

OBJECTIVES: Laryngopharyngeal reflux (LPR) is associated with inflammatory and neoplastic airway diseases. Gastric pepsin internalized by airway epithelial cells during reflux contributes to oxidative stress, inflammation, and carcinogenesis. Several plant extracts and compounds inhibit digestive enzymes and inflammatory or neoplastic changes to the esophagus in models of gastroesophageal reflux. This study examined the potential of chemoprotective phytochemicals to inhibit peptic activity and mitigate pepsin-mediated damage of airway epithelial cells. METHODS: Cultured human laryngeal and hypopharyngeal epithelial cells were pretreated with curcumin (10 micromol/L), ecabet sodium (125 microg/mL), and anthocyanin-enriched black-raspberry extract (100 microg/mL) 30 minutes before treatment with pepsin (0.1 mg/mL; 1 hour; pH 7). Controls were treated with media pH 7 or pepsin pH 7 without phytochemicals. Cell damage and proliferative changes were assessed by electron microscopy, cell count, thymidine analog incorporation, and real-time polymerase chain reaction array. Pepsin inhibition was determined by in vitro kinetic assay. RESULTS: Micromolar concentrations of curcumin, ecabet sodium, and black-raspberry extract inhibited peptic activity and pepsin-induced mitochondrial damage and hyperproliferation. Curcumin abrogated pepsin-mediated depression of tumor suppressor gene expression and altered the subcellular localization of pepsin following endocytosis. CONCLUSIONS: Several phytochemicals inhibit the pepsin-mediated cell damage underlying inflammatory or neoplastic manifestations of LPR. Dietary supplementation or adjunctive therapy with phytochemicals may represent novel preventive or therapeutic strategies for LPR-attributed disease.

Ketamine induces toxicity in human neurons differentiated from embryonic stem cells via mitochondrial apoptosis pathway.

Ketamine is widely used for anesthesia in pediatric patients. Growing evidence indicates that ketamine causes neurotoxicity in a variety of developing animal models. Our understanding of anesthesia neurotoxicity in humans is currently limited by difficulties in obtaining neurons and performing developmental toxicity studies in fetal and pediatric populations. It may be possible to overcome these challenges by obtaining neurons from human embryonic stem cells (hESCs) in vitro. hESCs are able to replicate indefinitely and differentiate into every cell type. In this study, we investigated the toxic effect of ketamine on neurons differentiated from hESCs. Two-week-old neurons were treated with different doses and durations of ketamine with or without the reactive oxygen species (ROS) scavenger, Trolox. Cell viability, ultrastructure, mitochondrial membrane potential (ΔΨm), cytochrome c distribution within cells, apoptosis, and ROS production were evaluated. Here we show that ketamine induced ultrastructural abnormalities and dose- and time-dependently caused cell death. In addition, ketamine decreased ΔΨm and increased cytochrome c release from mitochondria. Ketamine also increased ROS production and induced differential expression of oxidative stress-related genes. Specifically, abnormal ultrastructural and ΔΨm changes occurred earlier than cell death in the ketamine-induced toxicity process. Furthermore, Trolox significantly decreased ROS generation and attenuated cell death caused by ketamine in a dose-dependent manner. In conclusion, this study illustrates that ketamine time- and dose-dependently induces human neurotoxicity at supraclinical concentrations via ROS-mediated mitochondrial apoptosis pathway and that these side effects can be prevented by the antioxidant agent Trolox. Thus, hESC-derived neurons might provide a promising tool for studying anesthetic-induced developmental neurotoxicity and prevention strategies.

Phosphatidylethanolamine at the luminal endothelial surface--implications for hemostasis and thrombotic autoimmunity.

OBJECTIVE: Accumulating evidence suggests that phosphatidylethanolamine (PE) is physically present at the luminal endothelial surface, where it tentatively functions as a critical anticoagulant. The goal of the current investigation was 3-fold: to characterize the distribution profile of PE at the luminal endothelial surface; to examine the immunoreactivity to the vascular endothelium by anti-PE (aPE) sera from patients presenting with thrombosis; and to discuss the potential mechanism of PE upregulation by endothelial cells. METHODS: The rat aortic arch was selected as major conduit vessel under significant hemodynamic burden. The presence of PE and the antigenic profile of aPE sera at the luminal endothelial surface were examined using duramycin as a PEbinding probe and immunohistochemistry. Phosphatidylethanolamine upregulation at endothelial cell surface was investigated using cultured monolayer subject to laminar shear stress or thrombin treatment. RESULTS: High levels of PE were detected at the luminal endothelial surface of aortic flow dividers, the ascending aorta, and the outer curvature of the aortic arch. The antigenic profiles of aPE sera, which are highly associated with elevated thrombotic risks in patients, are consistent with PE distribution along the endothelial surface. Finally, PE is upregulated at the surface of cultured endothelial cells in response to luminal shear stress but not thrombin. CONCLUSIONS: The current data describe the physical distribution of vascular PE at the blood-endothelium interface. The luminal PE presents a vulnerability to anti-PE autoimmunity and is consistent with the association between aPE and elevated risk for idiopathic thrombosis.

Rationale for targeting pepsin in the treatment of reflux disease.

OBJECTIVES: We undertook to (1) obtain unequivocal evidence to confirm or rebut our initial observations that pepsin is taken up by hypopharyngeal epithelial cells by receptor-mediated endocytosis, (2) investigate whether uptake of pepsin at pH 7, in nonacidic refluxate, is of pathological significance, and 3) test our hypothesis that inactive but stable pepsin (

Pepsin in nonacidic refluxate can damage hypopharyngeal epithelial cells.

OBJECTIVES: Studies using combined multichannel intraluminal impedance with pH monitoring reveal a role for nonacidic reflux in laryngopharyngeal symptoms and injury. We have discovered that pepsin is taken up by laryngeal epithelial cells by receptor-mediated endocytosis. This finding reveals a novel mechanism by which pepsin could cause cell damage, potentially even in nonacidic refluxate. The objective of this study was to determine whether pepsin, at pH 7.4 and thus in nonacidic refluxate, causes cell damage. METHODS: Cultured hypopharyngeal epithelial (FaDu) cells were exposed to human pepsin (0.1 mg/mL) at pH 7.4 for either 1 hour or 12 hours at 37 degrees C and analyzed by electron microscopy, cytotoxicity assay, and SuperArray. RESULTS: We report mitochondrial and Golgi complex damage in cells exposed to pepsin at neutral pH, observed by electron microscopy. We also report cell toxicity of pepsin at pH 7.4, measured by a cytotoxicity assay. Furthermore, using SuperArray, we found that pepsin at pH 7.4 significantly alters the expression levels of multiple genes implicated in stress and toxicity. CONCLUSIONS: These findings are perhaps the first to explain why many patients have symptoms and injury associated with nonacidic reflux, and could have important implications for the development of new therapies for reflux, such as pepsin receptor antagonists and/or irreversible inhibitors of peptic activity.

Receptor-mediated uptake of pepsin by laryngeal epithelial cells.

OBJECTIVES: Previous data suggest a mechanistic link between exposure to pepsin and cellular changes that lead to laryngopharyngeal disorders. Initial confocal microscopy analysis of pepsin uptake by cultured hypopharyngeal epithelial cells revealed that pepsin may be taken up by a specific process. The objective of this study was to use electron microscopy to confirm the initial confocal findings and to determine whether uptake of pepsin by laryngeal epithelial cells is receptor-mediated. METHODS: Cultured human hypopharyngeal FaDu cells and human laryngeal biopsy specimens, taken from the posterior larynx of "control" patients without symptoms or findings of laryngopharyngeal reflux, were exposed to purified human pepsin 3b with or without transferrin (a marker for receptor-mediated endocytosis) in vitro. Uptake of pepsin was documented by electron microscopy. RESULTS: Pepsin co-localized with transferrin in intracellular vesicles; this finding confirms that pepsin is taken up by laryngeal epithelial cells by receptor-mediated endocytosis. CONCLUSIONS: This is a novel finding that further defines the role and mechanism of pepsin-mediated injury in laryngopharyngeal reflux. The objective of ongoing research is to identify the receptor and investigate potential antagonists as a new therapeutic option for patients with reflux-attributed disease--in particular, those patients who have persistent symptoms despite acid suppression therapy.

Factor VIII ectopically targeted to platelets is therapeutic in hemophilia A with high-titer inhibitory antibodies.

Inhibitory immune response to exogenously infused factor VIII (FVIII) is a major complication in the treatment of hemophilia A. Generation of such inhibitors has the potential to disrupt gene therapy for hemophilia A. We explore what we believe to be a novel approach to overcome this shortcoming. Human B-domain-deleted FVIII (hBDDFVIII) was expressed under the control of the platelet-specific alphaIIb promoter in platelets of hemophilic (FVIIInull) mice to create 2bF8trans mice. The FVIII transgene product was stored in platelets and released at the site of platelet activation. In spite of the lack of FVIII in the plasma of 2bF8trans mice, the bleeding phenotype of FVIIInull mice was corrected. More importantly, the bleeding phenotype was corrected in the presence of high inhibitory antibody titers introduced into the mice by infusion or by spleen cell transfer from recombinant hBDDFVIII-immunized mice. Our results demonstrate that this approach to the targeted expression of FVIII in platelets has the potential to correct hemophilia A, even in the presence of inhibitory immune responses to infused FVIII.