Identification of androgen receptor protein and 5alpha-reductase mRNA in human ocular tissues

BACKGROUND/AIMS

Androgens have been reported to influence the structural organisation, functional activity, and/or pathological features of many ocular tissues. In addition, these hormones have been proposed as a topical therapy for such conditions as dry eye syndromes, corneal wound healing, and high intraocular pressure. To advance our understanding of androgen action in the eye, the purpose of the present study was twofold: firstly, to determine whether tissues of the anterior and posterior segments contain androgen receptor protein, which might make them susceptible to hormone effects following topical application; and, secondly, to examine whether these tissues contain the mRNA for types 1 and/or 2 5alpha-reductase, an enzyme that converts testosterone to the very potent metabolite, dihydrotestosterone.

METHODS

Human ocular tissues and cells were obtained and processed for histochemical and molecular biological procedures. Androgen receptor protein was identified by utilising specific immunoperoxidase techniques. The analysis of type 1 and type 2 5alpha-reductase mRNAs was performed by the use of RT-PCR, agarose gel electrophoresis, and DNA sequence analysis. All immunohistochemical evaluations and PCR amplifications included positive and negative controls.

RESULTS

These findings show that androgen receptor protein exists in the human lacrimal gland, meibomian gland, cornea, bulbar and forniceal conjunctivae, lens epithelial cells, and retinal pigment epithelial cells. In addition, our results demonstrate that the mRNAs for types 1 and 2 5alpha-reductase occur in the human lacrimal gland, meibomian gland, bulbar conjunctiva, cornea, and RPE cells.

CONCLUSION

These combined results indicate that multiple ocular tissues may be target sites for androgen action.

MHC class II molecules, cathepsins, and La/SSB proteins in lacrimal acinar cell endomembranes

Sjögren's syndrome is a chronic autoimmune disease affecting the lacrimal glands and other epithelia. It has been suggested that acinar cells of the lacrimal glands provoke local autoimmune responses, leading to Sjögren's syndrome when they begin expressing major histocompatibility complex (MHC) class II molecules. We used isopycnic centrifugation and phase partitioning to resolve compartments that participate in traffic between the basolateral membranes and the endomembrane system to test the hypothesis that MHC class II molecules enter compartments that contain potential autoantigens, i.e., La/SSB, and enzymes capable of proteolytically processing autoantigen, i.e., cathepsins B and D. A series of compartments identified as secretory vesicle membranes, prelysosomes, and microdomains of the trans-Golgi network involved in traffic to the basolateral membrane, to the secretory vesicles, and to the prelysosomes were all prominent loci of MHC class II molecules, La/SSB, and cathepsins B and D. These observations support the thesis that lacrimal gland acinar cells that have been induced to express MHC class II molecules function as autoantigen processing and presenting cells.

Analysis of human sodium iodide symporter immunoreactivity in human exocrine glands

The human sodium iodide symporter (hNIS) is an intrinsic transmembrane protein that mediates the active transport of iodide across the basolateral membrane of thyroid follicular cells. In addition to normally functioning thyroid tissue, various extrathyroidal tissues, including salivary gland, lacrimal gland, gastric mucosa, choroid plexus, and lactating mammary gland, have been demonstrated to accumulate iodide. After cloning and molecular characterization of the sodium iodide symporter, expression of hNIS messenger ribonucleic acid has been detected in a broad range of extrathyroidal tissues using Northern blot analysis and RT-PCR. In this study we used both monoclonal and polyclonal antibodies directed against different portions of hNIS protein together with a highly sensitive immunostaining technique to assess hNIS protein expression in tissue sections derived from normal human salivary and lacrimal glands, pancreas, as well as gastric and colonic mucosa. Immunohistochemical analysis of normal human salivary and lacrimal glands revealed marked hNIS immunoreactivity in ductal cells and less intense staining of acinar cells. Further, immunostaining of gastric and colonic mucosa showed marked hNIS immunoreactivity confined to chief and parietal cells in gastric mucosa and to epithelial cells lining mucosal crypts in colonic mucosa. In normal human pancreas, hNIS immunoreactivity was located in ductal cells, exocrine parenchymal cells, and Langerhans islet cells. In conclusion, our study demonstrates the expression of hNIS protein by several human exocrine glands, suggesting that iodide transport in these glands is a specific property conferred by the expression of hNIS protein, which may serve important functions by concentrating iodine in glandular secretions.

Prolactin and prolactin receptors in the lacrimal gland

Light and electron microscopic immunocytochemistry, in situ hybridization and Dot Blot analysis revealed intracellular localization of prolactin-like molecules and prolactin mRNA in epithelial cells of the lacrimal glands of rabbits. There was also positive immunostaining for prolactin receptors on acinar cells and some interstitial cells. On Western blots of homogenates of whole lacrimal gland, isolated lacrimal acinar cells, isolated lacrimal interstitial cells and peripheral blood lymphocytes, prolactin antibody consistently labeled protein bands migrating at approximately 36 and 50 kD. These data confirm that lacrimal gland acinar cells produce endogenous prolactin-like molecules, but also express prolactin receptors. Since prolactin immunoreactivity has been detected in tear fluid and we found no accumulations of immunogold label in endocytic or transport vesicles, we hypothesize that the prolactin-like molecules in tear fluid originate primarily from synthesis within the acinar cells. We hypothesize further that prolactin from pituitary and other non-acinar cell origin has a modulating influence on acinar cell activity as well as immune function in the lacrimal gland, and that some of the prolactin-like molecules produced by the acinar cells contribute to these functions by autocrine/paracrine mechanisms.

Aquaporin-5 (AQP5), a water channel protein, in the rat salivary and lacrimal glands: immunolocalization and effect of secretory stimulation

Aquaporin-5 (AQP5) is a water channel protein and is considered to play an important role in water movement across the plasma membrane. We raised anti-AQP5 antibody and examined the localization of AQP5 protein in rat salivary and lacrimal glands by immunofluorescence microscopy. AQP5 was found in secretory acinar cells of submandibular, parotid, and sublingual glands, where it was restricted to apical membranes including intercellular secretory canaliculi. In the submandibular gland, abundant AQP5 was also found additionally at the apical membrane of intercalated duct cells. Upon stimulation by isoproterenol, apical staining for AQP5 in parotid acinar cells tended to appear as clusters of dots. These results suggest that AQP5 is one of the candidate molecules responsible for the water movement in the salivary glands.

Ca2+ signaling by cholinergic and alpha1-adrenergic agonists is up-regulated in lacrimal and submandibular glands in a murine model of Sjögren's syndrome

Innervation of the lacrimal gland of MRL/Mp-Fas-lpr/lpr (MRL/lpr), a murine model for Sjögren's syndrome, is unaltered with the onset or progression of the lymphocytic infiltration. To determine whether lacrimal and submandibular gland cells are able to respond to external stimuli, acini were prepared from MRL/lpr (diseased) and MRL/Mp-+/+ (MRL/+, control) mice at 4, 8, and 12 weeks of age and loaded with the fluorescent dye fura-2 to monitor changes in the intracellular Ca2+ concentration ([Ca2+]i) in response to cholinergic and alpha1-adrenergic stimulation, two major stimuli of lacrimal gland protein secretion. Cholinergic-induced [Ca2+]i increase was up-regulated 3- and 4-fold in lacrimal gland acini isolated from 8- and 12-week-old MRL/lpr mice, respectively, compared to 4-week-old animals, but was not up-regulated in age-matched MRL/+ control mice. Similarly, alpha1-adrenergic-induced [Ca2+]i increase was up-regulated 7- and 12-fold in acini isolated from 8- and 12-week-old MRL/lpr mice, respectively, compared to 4-week-old animals, but was not up-regulated in MRL/+ mice. Cholinergic-induced [Ca2+]i increase in submandibular gland acini of MRL/lpr and MRL/+ mice was the same at all ages. In contrast, alpha1-adrenergic-induced [Ca2+]i increase was up-regulated 3-fold in acini from 12-week-old MRL/lpr mice, compared to 4-week-old mice, but was not up-regulated in age-matched MRL/+ mice. We conclude that the Ca2+ signaling portion of cholinergic and alpha1-adrenergic pathway in the lacrimal gland and the Ca2+ signaling portion of alpha1-adrenergic pathway in the submandibular gland is up-regulated with the onset and progression of the lymphocytic infiltration in the MRL/lpr murine model of Sjögren's syndrome.

Functional anatomy of the human efferent tear ducts: a new theory of tear outflow mechanism

BACKGROUND

The mechanism of lacrimal drainage under physiological conditions is controversial. The aim of this study was to analyze the three-dimensional architecture of human efferent tear ducts from functional and clinical points of view. A new theory of tear outflow is discussed.

METHODS

Thirty-two prepared lacrimal systems of adults were examined by histological, immunohistochemical and scanning electron microscopic techniques.

RESULTS

The wall of the lacrimal sac is made up of collagen bundles, elastic and reticular fibers arranged in a helical pattern. Wide luminal vascular plexus are embedded in this helical system and connected to the cavernous tissue of the inferior turbinate in the region of Hasner's valve. Immunohistochemical analysis showed evidence of type I and type III collagen as well as chondroitin 4- and 6-sulfate.

CONCLUSION

With blinking, the lacrimal part of the orbicularis muscle contracts. The fornix of the sac moves in a cranial-lateral direction. Thus the lacrimal sac distends and may be "wrung out" due to its medial attachment and helically arranged fibrillar structures. The vascular plexus may play an important role in the absorption and drainage of lacrimal fluid.

Histochemical study on rat tear film and ocular surface epithelial cells

PURPOSE

To investigate the histochemistry of the tear film, conjunctival goblet cells and corneal superficial epithelial cells by an in vivo cryofixation with the freeze-substitution method.

METHODS

Following rapid freezing of the eyeballs by an isopentane-propane mixture cooled by liquid nitrogen directly, the specimens were freeze-substituted and then embedded in Lowicryl K4M resin at low temperature, or in epoxy resin for histochemical study, using light and transmission electron microscopy.

RESULTS

The tear film was weakly positive with periodic acid-Schiff staining, but negative with alcian blue at pH 2.5 or pH 1.0 and high iron diamine staining. Conjunctival goblet cells were positively stained by all these techniques. There was a gradually weakening staining intensity of mucus from the goblet cells to the conjunctival surface. With the periodic acid-thiocarbohydrazide-silver protein method the tear film was weakly stained, while glycocalices, vesicles, glycogen in epithelial cytoplasm and the mucus secretory granules of goblet cells were all intensely stained.

CONCLUSIONS

The tear film consists mainly of dilute mucus and contains either neutral or acid glycoproteins.

Cyclic AMP-receptor responses to hypergravity

BACKGROUND

Altered gravity (G) encountered during spaceflight causes physiologic changes in humans and in experimental animals. In addition to weightlessness (0G) in space, sharply increased G forces are exerted on the spacecraft during the lift-off and reentry phases. Previous studies showed major changes in cAMP-associated activity of rat heart muscle after spaceflight, indicating that (hormone) signaling pathways may have been affected.

HYPOTHESIS

The present study was designed to test the hypothesis that cAMP-related cellular responses of exocrine glands after simulated hypergravity (centrifugation at 1.7G) differ from the effects of 0G.

METHODS

A portion of the parotid and lachrymal gland tissue was fixed for morphologic and immunocytochemical study, and another was used for biochemical determinations. A short-term tissue culture was established from each gland to determine the effects of stimulation by norepinephrine. Heart muscle (ventricle) was also studied. Soluble and particulate fraction extracts of tissue homogenates were prepared, photoaffinity labeled with the [32P]8-N3-analog of cAMP, proteins separated by electrophoresis and the cAMP-reactive proteins (cARP) identified by autoradiography.

RESULTS

Differences were seen in protein banding patterns of the gland extracts and in altered cARP distribution in the 1.7G samples of heart ventricle and exocrine gland tissues, when compared with 1G controls. In the heart, cARP increased in the soluble fraction, while the particulate fraction extract showed no change. In acinar cells of the parotid, labeled cARP had accumulated, but decreased after stimulation to the level of the 1G controls. Immunogold labeling showed an increased content of amylase in the secretory granules of the 1.7G animals, while morphologic observation revealed few changes in the structure of parotid acinar cells. The response in the lachrymal gland was translocation of an isoform of cARP from the particulate to the cytoplasmic compartment.

CONCLUSIONS

Changes distinct from those due to 0G, but specific for hyper-G were found in cARP activity, protein synthesis, as well as in an apparent inhibition of regulated secretion.

Analysis of human ocular mucus: effects of neuraminidase and chitinase enzymes

PURPOSE

Our goal was to establish the characteristic migration pattern on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of high molecular weight mucins from human ocular mucus and the effects of treatment with exo- and endoglycosidases.

METHODS

Chromatography by gel filtration with Sepharose CL-4B was performed on samples collected from normal subjects. Human ocular mucins from the high molecular weight fraction were digested with exoglycosidases (neuraminidase, N-acetyl-beta-D-glucosaminidase, beta-D-glucosidase) and endoglycosidases (chitinase, lysozyme); and the resulting products were analyzed by electrophoresis. Carbohydrate identification was performed using lectin probes.

RESULTS

The migration of the ocular mucins on SDS-PAGE stopped after treatment with neuraminidase, which removes the terminal negatively charged sialic acid residues from mucin. Chitinase (beta(1-4)N-acetylglucosaminidase) treatment increased the electrophoretic migration of mucins. Staining with wheat germ agglutinin and Maackia amurensis agglutinin lectins showed that these mucins contain beta(1-4)NAcGlc and SAa(2-3)Gal linkages.

CONCLUSIONS

These studies demonstrate that the mobility of human ocular mucins on SDS-PAGE is determined by their intrinsic total negative charge and is not dependent on SDS treatment. It is interesting to note that human ocular mucus contains chitinous material resistant to lacrimal lysozyme, which is accessible to chitinase, an enzyme now found to degrade human ocular mucins. These chitinous linkages could be in part responsible for the mucus resistance.

Immunolocalization of aquaporin homologs in mouse lacrimal glands

It was shown recently that the aquaporin family of water channels exists in lacrimal gland cells. To determine the localization of aquaporin homologs and the pathophysiological modification of aquaporins by pilocarpine, a muscarinic agonist, we performed immunohistochemistry and immunoblotting in mouse lacrimal glands. By immunohistochemistry, aquaporin-4 (AQP4) and aquaporin-5 (AQP5) were found to be the lacrimal glands. AQP5 immunolabeling was detected in the apical membranes of the acinus and duct cells, while AQP4 was expressed in the basolateral membranes only. The tear secretion of mice systemically treated with pilocarpine was significantly (2.5-fold) higher than that of the saline-treated controls. The antibody to the AQP5 carboxy terminus showed high immunoreactivity on the apical membrane in the pilocarpine-treated lacrimal glands but not on that of saline-treated controls. However, the antibody to the extracellular domain of AQP5 showed similar immunolabeling in both groups of animals. In contrast, the immunoreactivity of AQP4 was not affected by pilocarpine stimulation. As shown by western blot analysis, the expression level of AQP5 on the apical membrane in the pilocarpine-stimulated lacrimal glands was not significantly different compared with the saline-treated controls. We conclude that AQP4 and AQP5 water channels are expressed on mouse lacrimal gland cells, with greater expression of AQP4 on the basolateral membrane and of AQP5 on the apical membrane. Furthermore, the AQP5 carboxy terminus region may undergo pathophysiological modification when tear secretion is increased by pilocarpine stimulation.

Cholinergic stimulation of lacrimal acinar cells promotes redistribution of membrane-associated kinesin and the secretory protein, beta-hexosaminidase, and increases kinesin motor activity

The role of the microtubule-based motor, kinesin, in membrane trafficking has been investigated in resting and stimulated acinar cells from rabbit lacrimal gland, a cholinergically controlled secretory tissue. Microtubule-dependent motors from extracts of control and carbachol-treated acini were isolated by microtubule-affinity purification and their activity was determined using a video-enhanced differential interference contrast microscopy assay for microtubule gliding. The observation that carbachol treatment resulted in a 2.2-fold stimulation of the frequency of GTP-dependent microtubule gliding in fractions isolated by microtubule-affinity purification and GTP release suggested that kinesin was a target of carbachol-induced stimulation. Resolution of membranes from resting cells by fractionation on a sorbitol density gradient followed by partitioning analysis in a dextran-polyethyleneglycol two-phase system revealed that membrane-associated kinesin codistributed with Golgi-derived membranes, a post-Golgi secretory compartment designated Hex1, membranes from a trans Golgi network-like compartment, endoplasmic reticulum and a group of putative lysosomal membranes containing cathepsin B. Comparable fractionation of carbachol-treated acini showed that stimulation caused redistributions of membrane-associated kinesin, the secretory enzyme beta-hexosaminidase, and galactosyltransferase that appeared to reflect both a reorganization within the Golgi complex and a return of material to the Golgi complex from the secretory pathway. Our findings that carbachol promotes activation of lacrimal acinar kinesin as well as major shifts in kinesin-membrane association within the secretory pathway suggests that kinesin plays a major role in secretory vesicle assembly, apical secretion, and/or secretory vesicle membrane recycling in the lacrimal gland.

Structure and composition of rat precorneal tear film. A study by an in vivo cryofixation

PURPOSE

To visualize the in vivo structure and to investigate the composition of rat precorneal tear film.

METHODS

An in vivo cryofixation with freeze substitution method of electron microscopy was used for the study. For light and transmission electron microscopy, a small amount of aluminum powder was used as a tracer spread on the corneal surface. The eyeballs were immediately and quickly frozen by pouring an isopentane-propane mixture cooled by liquid nitrogen directly over the eyes. For scanning electron microscopy, the corneal surface was freeze-fractured after the cryofixation. The specimens were then freeze-substituted and prepared conventionally for microscopic observation.

RESULTS

The tear film appeared as a layer of homogeneous and fine network-like structures varying from 2 to 6 microns in thickness on the corneal surface, with a membrane-like layer covering its surface. The aluminum powder was located on the surface of the tear film. The tear film could be removed completely by applying 10% or 20% acetylcysteine, but not by phosphate buffer.

CONCLUSIONS

The in vivo structure of the rat tear film is composed primarily of mucus, with a lipid layer covering its surface but without a free aqueous layer. The "three layers theory" of tear film structure requires revisions.

Distribution of endothelin and endothelin-A receptor in the lacrimal glands of the monkey (Macaca fuscata)

Endothelin (ET) is well known to be a potent vasoconstrictor peptide with autocrine and paracrine function. It has been documented that ET is also present in non-muscle tissues. The distribution of ET and ET-A receptor (ET-AR) in the monkey lacrimal gland was investigated by immunohistochemistry. Three adult male monkeys (Macaca fuscata) were perfused with a fixative. The lacrimal glands were then dissected and sectioned. Using rabbit anti-ET and anti-ET-AR antibodies, the immunohistochemical procedure was performed following an ABC technique. Some sections were treated with rhodamine-phalloidin, which selectively binds to actin filaments. ET immunoreactivity was present in stellate-shaped cells located around the alveoli. In sections double-stained with anti-ET antibody and rhodamine-phalloidin, ET immunoreactivity and abundant filamentous actin were identified in the same stellate cells. Immunostaining for ET-AR was also found in the stellate shape cells. The configuration of, and the abundance of actin filaments in the stellate-shaped ET- and ET-AR immunoreactive cells suggest that they are myoepithelial cells, which are contractile and may contribute to the process of lacrimal gland secretion or maintenance of the contour of the glandular endpieces. Our results indicate that endothelin is present in myoepithelial cells of the monkey lacrimal gland.

Localization of glycosaminoglycans and CD44 in the human lacrimal gland

Recent analyses of tears indicate the presence of glycosaminoglycans as their components, but their origin remains unknown. To further understand the origin of these tear components, we investigated by immunohistochemical techniques the localization of glycosaminoglycans and CD44 human lacrimal glands obtained from 20 cadavers at autopsy. Monoclonal antibodies to CD44, a receptor for hyaluronic acid, dermatan sulfate, chondroitin sulfate, and keratan sulfate were applied to the tissue. Hyaluronic acid binding region was also used for the staining of hyaluronic acid. By light microscopy, immunoreactivity for CD44 was mostly detected on the baso-lateral membrane of acinar and ductal cells, and the vascular endothelium in the interstitium. Positive staining of hyaluronic acid was associated intensely with the basal membrane of acinar and ductal cells and weakly, faintly or not at all with their lateral membrane. Positive staining of hyaluronic acid and immunoreactivity for dermatan sulfate were detected in interstitial fibrous structures; particularly, the former was intense in the perivascular fibrous structures, and the latter along the periparenchimal fibrous structures. Immunoreactivity for chondroitin sulfate and keratan sulfate was seen in some acinar cells and the acinar and ductal lumen. By electron microscopy, immunogold particles indication chondroitin sulfate sulfate or keratan sulfate labeled secretory granules of the acinar cells. Considering the fact that CD44 is a receptor molecule for hyaluronic acid, the association of hyaluronic acid with the basal membrane and weakly or faintly with the lateral membrane of acinar and ductal cells may be attributed to the expression of CD44 on the baso-lateral membrane of the cells. Moreover, the presence of immunoreactivity for chondroitin sulfate and keratan sulfate in secretory granules of acinar cells and their lumens suggests that tears from the lacrimal gland contain these glycosaminoglycans.

T-cell receptor repertoire of infiltrating T cells in lachrymal glands, salivary glands and kidneys from alymphoplasia (aly) mutant mice: a new model for Sjögren's syndrome

Alymphoplasia (aly) mice are thought to provide a new model for systemic Sjögren's syndrome (SS), since they reveal remarkable infiltration of mononuclear cells into salivary glands, lachrymal glands and kidneys, and show histological findings similar to those in patients with SS. Cell transfer experiments demonstrate that T cells induce the infiltration of mononuclear cells into several tissues in aly mice. To analyse the pathogenesis of cell infiltration in various tissues, we examined T-cell receptor (TCR) V beta usage of T cells in salivary glands, lachrymal glands and kidneys from aly mice, using family-polymerase chain reaction (PCR) and PCR-single-strand conformation polymorphism (SSCP) methods. The results of SSCP demonstrated that the infiltrating T cells in the three organs expanded clonally, suggesting that they proliferate by antigen-driven stimulation. Some TCR V beta genes (V beta 1, 3, 6, 11, 12, 16) were commonly used in salivary glands, lachrymal glands and kidneys, while the V beta 7 gene was specifically expressed in kidneys. SSCP also showed that there were a few shared T-cell clones (V beta 3- and V beta 6-positive cells) among the three tissues. Indeed, sequence analysis of accumulated T cells showed that a conserved amino acid (leucine) at position 98 in the TCR V beta complementary determining region (CDR) 3 was detected in all organs at high frequency (41-57%) and the amino acid sequence motif (LG) was specifically conserved at a frequency of 32% in the three organs. In conclusion, T cells that infiltrate into lachrymal glands, salivary glands and kidneys of aly mutant mice might recognize shared common epitopes in all three organs and a kidney-specific antigen.

Pattern of distribution of neuropeptides in the camel lacrimal gland

The pattern of distribution of neuropeptides, including neuropeptide-Y (NPY), vasoactive intestinal polypeptide (VIP), neurotensin (NT), serotonin (5-HT), galanin (GAL), leucine-enkephalin (LEU-ENK) and calcitoningene-related-peptide (CGRP), in the nerves of the camel lacrimal gland was investigated using immunohistochemical techniques. Fresh lacrimal gland segments, obtained from adult camels slaughtered in the local abattoir, were used for the immunohistochemical techniques. NPY and LEU-ENK immunoreactivity was observed in the nerve cell bodies and nerve fibers of the camel lacrimal gland. VIP, GAL and CGRP were demonstrated predominantly in fine varicose nerve fibers lying on the basolateral surfaces of the lacrimal acinar cells. NT and 5-HT were identified mainly in neurons situated in the periacinar regions, close to the basal surfaces of the acinar cells. It is concluded that the camel lacrimal nerves contain several neuropeptides including NPY, VIP, NT, 5-HT, GAL, LEU-ENK and CGRP which may modulate lacrimal fluid and protein secretion.

Evidence for the systemic delivery of a transgene product from salivary glands

The aim of this study was to assess the feasibility of using gene transfer to salivary glands to direct the systemic delivery of therapeutic proteins in vivo. We used a replication-deficient recombinant adenovirus vector (Ad alpha 1AT) that encodes human alpha 1-antitrypsin (h alpha 1-AT), which we used as a marker protein. Ad alpha 1AT (5 x 10(9) pfu) was administered by retrograde ductal instillation to the submandibular glands of male rats. The amount of h alpha 1-AT found in the salivary glands, saliva, serum, and other tissues was analyzed by a sensitive enzyme-linked immunosorbent assay (ELISA). Maximal levels of the marker protein were detected at 24-48 hr post-virus administration for glands (274 ng/mg protein), saliva (approximately 313 ng/ml), and serum (approximately 5 ng/ml). Serum levels remained elevated for 96 hr, whereas the measured half-life for the marker protein was approximately 2 hr. Generally little to no h alpha 1-AT was detectable in most other organs. However, we were able to measure low levels of marker protein in tissues immediately surrounding infected glands. In all animals studied, levels of h alpha 1-AT were higher in the glandular venous effluent than in arterial blood. Similar results were found with parotid glands. The aggregate data demonstrate that salivary glands may be a target for the nonsurgical, systemic delivery of transgene-encoded therapeutic proteins for diseases that require relatively low circulating protein levels.

Local and systemic specific antibody response of different chicken lines after ocular vaccination against infectious bronchitis

The specific lacrimal fluid IgA levels and the specific serum IgG levels of broiler chicks (meat type hybrids (MT)), brown-egg layer chicks (heavy layer (HL)), and white leghorn chicks (light layer (LL)) were compared after infectious bronchitis virus (IBV) ocular vaccination at 1 day of age. All birds were maintained as a mixed population throughout the experiment of 45 days. The class specific antibody levels were determined at regular intervals by enzyme-linked immunosorbent assays. All birds responded to the vaccination stimulus as shown by a significant increase of antibody levels in both serum and lacrimal fluid. When comparing the IgG response of the chicken lines tested, LL chicks showed higher serum IBV-IgG values at the time of maximal response at days 5 and 9 post-vaccination (pv). This bird group also showed a more homogeneous (lowest coefficient of variation of values) serum IgG response. On day 13 pv and until the last serum sampling day (day 41 pv) all three chicken types showed statistically identical serum IBV-IgG levels. The local IgA response detected in lacrimal fluids showed differences between the chicks at the time of maximal levels (days 5 to 14 pv), the response of LL chicks being the highest. LL chicks maintained higher specific IgA levels than MT and HL chicks almost throughout the experimental period. According to the coefficient of variation of the absorbance values (36%), the IgA response shown by LL chicks was the most homogeneous.

Immunohistochemical and histochemical characterisation of epithelial cells of rabbit lacrimal glands in tissue sections and cell cultures

The purpose of this study was to establish conditions for isolation and long term culture of acinar cells from the Harderian gland, and superior and inferior lacrimal glands of the rabbit and to compare the in vitro growth patterns of cultured cells from these glands. In order to determine the predominant cell type in the cultures, cells and tissue sections were stained using a variety of antibodies to cytokeratins, smooth muscle actin, and neuron specific enolase. Similarly, PAS and alcian blue histochemistry were used to test for the presence of mucins. The glands were excised and cells isolated using enzymatic digestion and then established in long term culture. Different media and substrata were trialed for suitability. When cultured on uncoated Costar plastic in DMEM/10%FBS, the pattern of cell growth was similar for all glands with distinct phases involving aggregation and migration out from the aggregates before cells died between 20 to 30 days. Immunohistochemical staining indicated that the cultures were of acinar cells with a small percentage of ductal cells. The acinar cells of the lacrimal glands in situ and in vitro stained with antibody MNF116 directed against cytokeratins 5, 6, 8 and 17 but did not stain for antibodies to cytokeratin 18. The reverse staining pattern was true for the Harderian gland. Sections from the white lobe of the Harderian gland showed islets of serous secreting cells which showed positive staining when MNF116 was used. In situ, PAS positive cells were found in a small number of demilunes in the superior and inferior lacrimal glands and also in cells of the intercalated ducts. Surprisingly, in culture nearly all cells, including those isolated form the Harderian gland became PAS positive. In this study we have demonstrated that acinar cells from the Harderian and lacrimal glands of rabbit can be isolated and maintained in culture for 20 to 30 days, and that despite dramatic morphological changes, these cells retain their distinctive phenotype as indicated by antibody staining to specific cellular structural proteins such as cytokeratins and actin. However, the cultured cells also begin to produce mucins as indicated by PAS staining.

"BM180": a novel basement membrane protein with a role in stimulus-secretion coupling by lacrimal acinar cells

Regulated secretion requires the developmental coupling of neuronal or hormonal stimuli to an exocytotic response, a multistep pathway whose appearance may be linked with cellular adhesion to the newly formed exocrine cell basement membrane. We screened for adhesion-associated coupling activity using lacrimal acinar cells and have identified "BM180", a novel basement membrane protein enriched in guanidine HCl extracts of lacrimal and parotid exocrine secretory glands. BM180 resides primarily in a previously inexamined lower molecular-mass basement membrane peak (peak 2) that contains cell adhesion activity inhibitable with the anti-BM180 monoclonal antibody 3E12. Removal of peak 2 by gel filtration or preincubation of basement membrane with 3E12 decreased regulated peroxidase secretion by one-half without affecting constitutive secretion or the amount of cellular peroxidase available for release. Adding back peak 2 restored regulated secretion in a dose-dependent and 3E12-inhibitable manner and suggested a synergistic relationship between BM180 and laminin 1. BM180 has a mobility of 180 and 60 kDa in the absence or presence of dithiothreitol, respectively, and shows no immunological identity by competitive enzyme-linked immunosorbent assay with laminin 1, collagen IV, entactin, fibronectin, BM-40, perlecan, or vitronectin. We propose that BM180 is an important resident of certain glandular basement membranes where it interacts with the cell surface, thereby possibly signaling the appearance of a transducing element in the stimulus-secretion coupling pathway.

Hepatocyte growth factor and hepatocyte growth factor receptor in the lacrimal gland, tears, and cornea

PURPOSE

The purpose of this study was to characterize the expression of hepatocyte growth factor (HGF) and HGF receptor proteins in lacrimal gland, tears, and cornea.

METHODS

The reverse transcription-polymerase chain reaction method was used to detect HGF and HGF receptor messenger RNA in human lacrimal gland tissue. HGF and HGF (c-met) receptor monoclonal antibody specificity was demonstrated with fluorescent antibody sorting of cells engineered to express HGF or HGF receptor compared with control cell lines, enzyme-linked immunoadsorbent assay (ELISA), immunoprecipitation, and immunohistology with preabsorption. Immunohistochemistry was applied to study the distribution of HGF and HGF receptor expression in rabbit lacrimal gland tissue and in wounded and unwounded rabbit cornea. An ELISA was used to detect HGF in pooled samples of human tears and individual aliquots of tears collected from patients 1 day after anterior segment surgery.

RESULTS

Amplification products of the expected size for HGF and HGF receptor mRNAs were detected in lacrimal tissue and were confirmed to be specific by hot blotting and nucleic acid sequencing. Hepatocyte growth factor protein was detected in interalveolar and interlobular connective tissue cells adjacent to glandular alveolar (acinar) cells and associated with the cells lining the interlobular ducts. Hepatocyte growth factor receptor protein was expressed in the glandular alveolar and interlobular ductal cells in the lacrimal gland and all three cell types of the cornea. It was detected in keratocyte and endothelial cells, and expression was increased in keratocytes after epithelial wounding. Hepatocyte growth factor was not present in corneal epithelial cells, but in the unwounded cornea a strong signal was associated with the epithelial cell surface. It was detected by ELISA in pooled normal tears at levels 186 to 290 pg/ml and in individual postoperative tear samples at 453 to 619 pg/ml. In some tear samples, HGF levels were below the sensitivity of the assay (97.5 pg/ml).

CONCLUSIONS

The distribution of HGF receptor protein expression in the lacrimal gland suggests that HGF secreted by interalveolar connective tissue cells traverses the acinar cells and modulates functions in acinar and ductal epithelial cells. Hepatocyte growth factor likely collects within the interlobular ducts and becomes a component in normal tears. Thus, lacrimal gland HGF probably modulates corneal epithelial cell proliferation, motility, and differentiation. Its expression in keratocytes is upregulated after corneal epithelial wounding and probably contributes to the epithelial wound healing process.

Immunolocalization of myoepithelial cells in isolated acini of rat exorbital lacrimal gland: cellular distribution of muscarinic receptors

The secretion of proteins and fluids from the exorbital lacrymal gland of rat is mainly controlled by muscarinic receptors. In a recent pharmacological study. Mauduit et al (Am J Physiol (1993) 264, C1550-C1560) identified a homogeneous population of M3 muscarinic receptors in preparations of acini from these tissues. In order to define the cellular composition of these acini and localize the muscarinic receptors, we have performed an immunofluorescent labelling study combined with confocal scanning microscopy. Antibodies raised against components of the different cytoskeletal networks (alpha-smooth muscle actin, cytokeratin peptide 14 and alpha-tubulin) revealed the presence of two different cell types. Cells with a stellate form are identified as myoepithelial cells, whereas rounded cells are secretory acinar cells. Both cell types are reactive with an antibody specifically directed against the muscarinic receptor. However, myoepithelial cells appear more intensely labelled than acinar cells. The roles of myoepithelial cells and secretory cells in the physiological function of the gland are discussed in terms of the distribution of muscarinic receptors.