Biomedical subjects

Paul B McCray

Publications and source records attributed to Paul B McCray.

40 records · Page 3Linked to original sources

PubMed2002

Measles virus preferentially transduces the basolateral surface of well-differentiated human airway epithelia.

Measles virus (MV) is typically spread by aerosol droplets and enters via the respiratory tract. The progression of MV infection has been widely studied; yet, the pathway for virus entry in polarized human airway epithelia has not been investigated. Herein we report the use of a replication-competent Edmonston vaccine strain of MV expressing enhanced green fluorescent protein (MV-eGFP) to infect primary cultures of well-differentiated human airway epithelia. Previous studies with polarized Caco-2 cells (intestine-derived human epithelia) and MDCK cells (kidney-derived canine epithelia) demonstrated that MV primarily infected and exited the apical surface. In striking contrast, our results indicate that MV preferentially transduces human airway cells from the basolateral surface; however, virus release remains in an apical direction. When MV-eGFP was applied apically or basolaterally to primary cultures of airway epithelia, discrete foci of eGFP expression appeared and grew; however, the cell layer integrity was maintained for the duration of the study (7 days). Interestingly, utilizing immunohistochemistry and confocal microscopy, we observed widespread expression of the receptor for the vaccine strain of MV (CD46) at greatest abundance on the apical surface of the differentiated human airway epithelia as well as in human tracheal tissue sections. These data suggest that the progression of MV infection through the respiratory epithelium may involve pathways other than direct binding and entry through the apical surface of airway epithelia.

Antigens, CD↗

PubMed2002

[beta]-defensins in lung host defense.

Host defenses at the mucosal surface of the airways evolved to present many layers of protection against inhaled microbes. Normally, the intrapulmonary airways are sterile. Airway secretions contain numerous factors with antimicrobial activity that contribute to innate defenses. Many protein and peptide components exert bacteriostatic or bacteriocidal effects against a wide variety of organisms and may act in synergistic or additive combinations. The beta-defensins are a relatively recently described family of peptide antimicrobials that are widely expressed at mucosal surfaces, including airway and submucosal gland epithelia. These small cationic peptides are products of individual genes that exhibit broad-spectrum activity against bacteria, fungi, and some enveloped viruses. Their expression in airway epithelia may be constitutive or inducible by bacterial products or pro-inflammatory cytokines. beta-defensins also act as chemokines for adaptive immune cells, including immature dendritic cells and T cells via the CCR6 receptor, and provide a link between innate and adaptive immunity. Alterations in the function of the beta-defensins may contribute to disease states. Here we review much of the biology of the beta-defensins, including gene discovery, genomic organization, molecular structure, regulation of expression, and function.

Amino Acid Sequence↗

PubMed2002

Endogenous and exogenous glucocorticoid regulation of ENaC mRNA expression in developing kidney and lung.

Lung liquid absorption at birth is crucial for the successful onset of respiration. Na absorption by the renal collecting duct plays an important role in renal fluid and electrolyte homeostasis during the early postnatal period. The epithelial Na channel (ENaC) plays a central role in mediating these functions, and its subunit expression is developmentally regulated in a temporal and tissue specific pattern. Several lines of evidence suggest that the prenatal increase in circulating glucocorticoids may play an important role in increasing ENaC expression during maturation. We tested the role of the prenatal surge using corticotropin-releasing hormone (CRH) knockout (KO) mice. Relative ENaC expression in lungs of KO mice increased at the same rate as in wild-type (WT) mice, but absolute expression was only 20-30% of WT. In contrast, relative and absolute expression of all three subunits in kidneys was not different between KO and WT mice. Dexamethasone (Dex) increased alpha-ENaC mRNA in fetal lung and kidney explants within 24 h but had different effects on beta- or gamma-ENaC. Dex increased beta- and gamma-ENaC in lung, but only after >48 h of exposure, and had no effect on kidney. The results suggest that the kidney metabolizes endogenous glucocorticoids, but the lung does not. Furthermore, the marked difference between lung and kidney responsiveness to glucocorticoids in beta- and gamma-ENaC expression suggests that factors other than steroids may be important in regulating functional ENaC expression during development.

Animals↗

PubMed2001

The solution structures of the human beta-defensins lead to a better understanding of the potent bactericidal activity of HBD3 against Staphylococcus aureus.

The three human beta-defensins, HBD1--3, are 33--47-residue, cationic antimicrobial proteins expressed by epithelial cells. All three proteins have broad spectrum antimicrobial activity, with HBD3 consistently being the most potent. Additionally, HBD3 has significant bactericidal activity against Gram-positive Staphylococcus aureus at physiological salt concentrations. We have compared the multimeric state of the three beta-defensins using NMR diffusion spectroscopy, dynamic and static light scattering, and analysis of the migration of the three beta-defensins on a native gel. All three techniques are in agreement, suggesting that HBD-3 is a dimer, while HBD-1 and HBD-2 are monomeric. Subsequently, the NMR solution structures of HBD1 and HBD3 were determined using standard homonuclear techniques and compared with the previously determined solution structure of HBD2. Both HBD1 and HBD3 form well defined structures with backbone root mean square deviations of 0.451 and 0.616 A, respectively. The tertiary structures of all three beta-defensins are similar, with a short helical segment preceding a three-stranded antiparallel beta-sheet. The surface charge density of each of the defensins is markedly different, with the surface of HBD3 significantly more basic. Analysis of the NMR data and structures led us to suggest that HBD3 forms a symmetrical dimer through strand beta2 of the beta-sheet. The increased anti-Staphylococcal activity of HBD3 may be explained by the capacity of the protein to form dimers in solution at low concentrations, an amphipathic dimer structure, and the increased positive surface charge compared with HBD1 and HBD2.

Amino Acid Sequence↗