Hepatocyte growth factor stimulates adenoviral-mediated gene transfer across the apical membrane of epithelial cells.

BACKGROUND: The apical surface of polarized epithelial cells is relatively resistant to gene delivery by various agents including adenoviral vectors. Hepatocyte growth factor (HGF) dedifferentiates previously well-polarized Madin-Darby canine kidney (MDCK) cell monolayers by altering cell-surface polarity and inhibiting tight junction function. METHODS: We used an in vitro model of polarized MDCK cells grown on permeable supports to examine the effects of HGF pretreatment on adenoviral (Ad)-mediated gene delivery through the apical surface of epithelial cell monolayers. RESULTS: HGF pretreatment of MDCK cell monolayers for 72 h increased Ad-mediated gene transfer and expression of enhanced green fluorescent protein (EGFP) and luciferase in a dose-dependent fashion. Time-course analysis of HGF-induced stimulation of Ad-mediated gene transfer was seen after 24 h and increased further with pretreatment periods extending to 72 h. HGF pretreatment increased Ad-mediated gene transfer at varying multiplicity of infection (MOI; ranging from 0.2-2000). PCR analysis for adenoviral DNA in control and HGF-pretreated MDCK cells suggested increased entry of viral constructs into HGF-pretreated MDCK cell monolayers. HGF-induced alterations in cell polarity are reversible upon removal of HGF. CONCLUSIONS: These data demonstrate that HGF pretreatment of MDCK cells increases the sensitivity of the cells to Ad-mediated gene delivery. The mechanism by which this occurs appears to be through increased entry of adenovirus into epithelial cells. These data provide evidence that biological agents that transiently alter epithelial cell polarity and tight junction function can be used to augment Ad-mediated gene delivery into epithelial cells from the apical surface.

Hepatocyte growth factor inhibits intrinsic antibacterial activity of Madin-Darby canine kidney cells.

We investigated whether or not polarized renal epithelial cells produce antibacterial factors, which aid in host defense at the cell surface of renal epithelium. A model of polarized Madin-Darby canine kidney (MDCK) epithelial cells grown on filters was used to test for the presence of apically or basolaterally secreted factors on the growth of non-virulent (XL1-Blue) and uropathogenic (J96) strains of Escherichia coli (E. coli). Growth of both XL1-Blue and J96 strains of E. coli in medium on the apical and basolateral surface of MDCK cells was inhibited as compared to bacterial growth in medium not exposed to MDCK cells. The inhibition of bacterial growth was similar in both apical and basolateral surface medium. Pretreatment of MDCK cells with hepatocyte growth factor (HGF) blunted the inhibition of XL1-Blue and J96 growth in apical and basolateral surface medium as compared to growth in medium on the surfaces of untreated MDCK cells. Immunofluorescent analysis demonstrated the presence of beta-defensin isoforms 1-3 in MDCK cells, with isoform 1 being the most prevalent form observed. HGF treatment reduced the amount of immunoreactive beta-defensin-1 in MDCK cells. These data demonstrate that polarized renal epithelium produce antibacterial factors. The renotropic growth factor HGF inhibits these antibacterial factors. beta-defensins may contribute to this antibacterial activity and play an important role in renal epithelial resistance to bacterial infections.

Cystic ectasia of the rete testis: clinical and radiographic features.

PURPOSE: Cystic ectasia of the rete testis is a rare condition that may be incidentally noted on scrotal ultrasonography. This benign condition has a typical appearance of a collection of small anechoic structures in the confluence of the mediastinum testis. The main significance of this condition is that it must be differentiated from testicular neoplasm. We reviewed the experience with this condition at our institution. MATERIALS AND METHODS: A retrospective review was performed to identify all sonograms showing ectatic rete testis performed from 1998 through February 2002. A departmental database was used to identify all scrotal sonograms from this period showing ectasia of the rete testis and clinical correlation was done. These examinations were then reviewed by a single radiologist. RESULTS: We identified 13 cases in the last 4 years. Ultrasound was most commonly performed for a testicular or scrotal mass, or pain. Median patient age was 65 years. All except 1 patient had an underlying condition, including vasectomy, epididymal cyst/spermatocele or inguinal hernia repair, that could cause epididymal or efferent duct obstruction. No patient had a solid testicular mass. CONCLUSIONS: Based on clinical and sonographic criteria the diagnosis of cystic ectasia of the rete testis can be made without histological confirmation. Identifying this entity and its associated conditions avoids the need for biopsy or orchiectomy.