Application Of Primary Antibodies Research Articles

P155 Visualisation of Airway Nerves in Chronic Cough: Towards the Identification of the Human ‘Cough Receptor’

Introduction The spinal and vagal innervation of the respiratory tract is well defined, particularly in animals. These discoveries include the identification of pathways involved in provoking cough and descriptions of the guinea pig ‘cough receptor’. However, many of the immunochemical features of the airway afferents described in animals have yet to be defined in humans, yet plasticity of these airway afferents may be important in the pathophysiology of chronic cough. Objectives To define and characterise the innervation present in bronchoscopic biopsies from patients with chronic cough. We aimed to carry out the first ever whole mount immunohistochemical studies of airway nerves in cough patients, a technique that should improve visualisation of these neuronal structures and their sites of termination. Methods Biopsy tissue was gifted from patients undergoing clinical investigation for chronic cough. Tissue, sampled from throughout the extrapulmonary airways, was immediately fixed in 4% paraformaldehyde. Non-specific antibody binding was blocked using 10% normal serum and 1% skimmed milk powder, diluted in PBS, before application of primary antibodies. Polyclonal rabbit anti-PGP9.5 (Ultraclone, UK) and monoclonal mouse anti-neurofilament (NF200, Leica Biosystems, UK) were applied at a dilution of 1:1000 and 1:200 respectively. Primary antibody binding was detected using appropriate Alexa-fluor conjugated secondary antibodies and whole mount preparations were visualised using epifluorescence and confocal microscopy. Images of biopsy staining were subject to morphometric analysis. Results Many epithelial, subepithelial and intramuscular fibres were detected using both antibodies. Co-staining revealed that only PGP9.5 defined pulmonary neuroendocrine cells and better elucidated varicose epithelial fibres. A proportion of all fibre types were only immunopositive for one marker. Notably NF200 exclusively detected some epithelial fibres and a group of larger diameter neurons (O3–6 µm) some of which are consistent with observations of Aδ-fibre airway mechanoreceptors. Conclusions We have described neuronal structures in whole-mount preparations of tissue from patients suffering from chronic cough. Notably, we described a population of PGP9.5 negative fibres within the airways. Some of these fibres are morphologically consistent with thinly myelinated Aδ-fibres described in animal models as ‘cough receptors’. These ongoing studies could help define the plasticity of airway nerves in patients with chronic cough.

Differential Recognition and Hydrolysis of Host Carbohydrate Antigens by Streptococcus pneumoniae Family 98 Glycoside Hydrolases

The presence of a fucose utilization operon in the Streptococcus pneumoniae genome and its established importance in virulence indicates a reliance of this bacterium on the harvesting of host fucose-containing glycans. The identities of these glycans, however, and how they are harvested is presently unknown. The biochemical and high resolution x-ray crystallographic analysis of two family 98 glycoside hydrolases (GH98s) from distinctive forms of the fucose utilization operon that originate from different S. pneumoniae strains reveal that one enzyme, the predominant type among pneumococcal isolates, has a unique endo-beta-galactosidase activity on the LewisY antigen. Altered active site topography in the other species of GH98 enzyme tune its endo-beta-galactosidase activity to the blood group A and B antigens. Despite their different specificities, these enzymes, and by extension all family 98 glycoside hydrolases, use an inverting catalytic mechanism. Many bacterial and viral pathogens exploit host carbohydrate antigens for adherence as a precursor to colonization or infection. However, this is the first evidence of bacterial endoglycosidase enzymes that are known to play a role in virulence and are specific for distinct host carbohydrate antigens. The strain-specific distribution of two distinct types of GH98 enzymes further suggests that S. pneumoniae strains may specialize to exploit host-specific antigens that vary from host to host, a factor that may feature in whether a strain is capable of colonizing a host or establishing an invasive infection.

Critical Role of Nucleostemin in Pre-rRNA Processing

Nucleostemin is a nucleolar protein widely expressed in proliferating cells. Nucleostemin is involved in the regulation of cell proliferation, and both depletion and overexpression of nucleostemin induce cell cycle arrest through the p53 signaling pathway. Although the presence of p53-independent functions of nucleostemin has been previously suggested, the identities of these additional functions remained to be investigated. Here, we show that nucleostemin has a novel role as an integrated component of ribosome biogenesis, particularly pre-rRNA processing. Nucleostemin forms a large protein complex (>700 kDa) that co-fractionates with the pre-60 S ribosomal subunit in a sucrose gradient. This complex contains proteins related to pre-rRNA processing, such as Pes1, DDX21, and EBP2, in addition to several ribosomal proteins. We show that the nucleolar retention of DDX21 and EBP2 is dependent on the presence of nucleostemin in the nucleolus. Furthermore, the knockdown of nucleostemin delays the processing of 32 S pre-rRNA into 28 S rRNA. This is accompanied by a substantial decrease of protein synthesis as well as the levels of rRNAs and some mRNAs. In addition, overexpressed nucleostemin significantly promotes the processing of 32 S pre-rRNA. Collectively, these biochemical and functional studies demonstrate a novel role of nucleostemin in ribosome biogenesis. This is a key aspect of the role of nucleostemin in regulating cell proliferation.

Contribution of Sensory Neurons to Sex Difference in the Development of Stress-Induced Gastric Mucosal Injury in Mice

Sensory neurons play a critical role in reducing stress-induced gastric mucosal injury by releasing calcitonin gene-related peptide (CGRP) through an increase in gastric mucosal levels of prostacyclin (PGI(2)). Because estrogen enhances nerve growth factor-mediated CGRP production in sensory neurons, we hypothesized that stress-induced gastric mucosal injury occurs less in females than in males. Gastric ulcer index, gastric myeloperoxidase activity, and gastric tissue levels of CGRP and 6-keto-PGF(1alpha), a stable metabolite of PGI(2), were determined in male and female wild-type (CGRP(+/+)) mice and CGRP knockout (CGRP(-/-)) mice subjected to water-immersion restraint stress. In CGRP(+/+) mice, ulcer index and myeloperoxidase activities were lower and gastric tissue levels of CGRP and 6-keto-PGF(1alpha) were higher in female mice than in male mice, but there were no such sex differences in CGRP(-/-)mice. Sex differences in CGRP(+/+) mice were eliminated by pretreatment with SB366791 (500 microg/kg intraperitoneally), a vanilloid receptor antagonist, and by ovariectomy. Reversal of sex differences by ovariectomy was not observed in female CGRP(+/+) mice with estradiol replacement (1 mg . kg(-1). wk(-1) for 3 weeks). Levels of CGRP messenger RNA in dorsal root ganglion neurons isolated from female CGRP(+/+) mice were decreased by ovariectomy, and these decreases were reversed by estradiol replacement. Estrogen-mediated increases in CGRP levels in sensory neurons might contribute to reduce stress-induced gastric mucosal injury by attenuating inflammatory responses. This might at least partly explain the sex difference observed in the development of stress-induced gastric mucosal injury in mice.

Vascular endothelial growth factor, FLT‐1, and FLK‐1 analysis in a pancreatic cancer tissue microarray

Measures of vascular endothelial growth factor (VEGF) expression in pancreatic cancer typically have been qualitative or semiquantitative. The objective of this study was to use a series of algorithms called AQUA that quantitatively assesses protein expression on tissue microarrays (TMAs) to compare in situ expression of VEGF and its primary receptors, VEGF receptor 1 (FLT-1) and VEGF receptor 1 (FLK-1), on a pancreatic cancer TMA. TMAs were constructed by arraying 1.5-mm cores from 76 samples of pancreatic adenocarcinoma (1996-2002) that were obtained from the archives of the Yale Department of Pathology. The staining for AQUA was similar to standard immunohistochemistry and involved antigen retrieval and the application of primary antibodies, but with epifluorescence detection. Slides were counterstained with 4',6-diamidino-2-phenylindole for nuclear visualization and cytokeratin for membrane visualization. The primary antibodies used were VEGF, FLT-1, FLK-1, and cytokeratin. Disease stage was highly prognostic for outcome, as expected. Total amounts of VEGF and its receptors were assessed within the tumor mask and were divided into quartiles. Kaplan-Meier survival curves showed that VEGF and FLK-1 were not associated clearly with outcome. However, the expression of FLT-1 was correlated significantly, and the patients who had tumors with the lowest expression FLT-1 levels had the worst survival (P = .0038). In multivariate analysis, FLT-1 expression was an independent prognostic factor for overall survival (P = .0044). VEGF and its 2 principal receptors were expressed to varying degrees in tumors of the pancreas. A significant association was found between low expression of FLT-1 and both poor prognosis and advanced stage, suggesting that tumor expression of this VEGF receptor is a marker of less aggressive disease.

Differential Expression of Cannabinoid Receptors in the Human Colon: Cannabinoids Promote Epithelial Wound Healing

Differential Expression of Cannabinoid Receptors in the Human Colon: Cannabinoids Promote Epithelial Wound Healing

Immunoassay Comparison of Haplosporidan Spores from Teredo navalis and Haplosporidium nelsoni Spores from Crassostrea virginica

ABSTRACTSpores of a haplosporidan infecting Teredo navalis Linnaeus have been described as morphologically indistinguishable from spores of Haplosporidium nelsoni. To test the hypothesis that these organisms are conspecific, a colloidal gold immunoassay was used to compare antigenic characteristics of the spores from both hosts. Rabbit antibody to formalin‐fixed spores from T. navalis was tested against paraffin sections of Crassostrea virginica infected with spores of H. nelsoni and against paraffin sections of infected 7″. navalis. Application of primary antibody was followed by addition of affinity purified goat anti‐rabbit IgG coaled on 5‐nm colloidal gold particles. The reaction was enhanced by precipitation of metallic silver; a positive reaction appeared as a dark brown to black signal at the site of each antigen‐antibody complex. Haplosporidium nelsoni spores did not react when assayed with the antibody made to spores from T. navalis. Spores from infected T. navalis tissue reacted positively with rabbit antibody. This result indicates that the spores from the 2 hosts are antigenicaliy distinct and suggests that they are different species.