Lacrimal Tissue Research Articles

A case of orbital malt lymphoma with breast involvement detected by 18FDG‐positron emission tomography

A diagnosis of right lacrimal gland mucosa-associated lymphoid tissue (MALT) lymphoma was made in a 71-year-old woman. Histological examination showed dense atypical lymphocytic infiltration. The tumour cells had small dark nuclei with abundant clear cytoplasm (top left, haematoxylin and eosin, ·200) and there was strong immunoreactivity for CD20 (·200; top right). The patient was referred for staging with 2-(F) fluorodeoxyglucose positron emission tomography (F-FDGPET) after surgery of the orbital lesion. Head/neck, thorax and abdomen computerised tomography had been performed previously, with no significant findings. Head and neck magnetic resonance imaging showed diffuse high signals in both, especially in the right inferior palpebral area, with no discrete mass, and with cervical lymphadenopathy, particularly on the right side; all nodes were <1 cm in diameter. An FDG-PET scan showed an area (2 · 3AE4 cm) of moderate hypermetabolism, in the left breast (bottom), but a mammogram did not show any significant abnormality. The breast lesion was evaluated by fine needle aspiration, which showed low-grade non-Hodgkin lymphoma, consistent with MALT lymphoma. Gastric involvement was ruled out by gastric biopsy, which showed no metaplasia or dysplasia, although there was atrophic gastritis, and Helicobacter pylori was present. The co-existence of orbital and breast MALT-type lymphoma has been previously reported (Chopra et al, 2005) but is rare. Although PET scanning is often used for staging lymphoma, its role in MALT-type lymphoma is uncertain, as this technique produces negative results in many patients with extranodal-marginal zone lymphoma. Further evaluation of its role is indicated.

Estrogen’s and Progesterone’s Impact on Gene Expression in the Mouse Lacrimal Gland

The hypothesis tested in the study was that the effect of estrogen and progesterone on the lacrimal gland is mediated through specific receptors and that hormonal effects involve the regulation of gene expression and protein synthesis. Lacrimal glands were collected from young adult, ovariectomized mice, that were treated with 17beta-estradiol, progesterone, 17beta-estradiol plus progesterone or vehicle for 2 weeks. Glands were pooled according to treatment, processed for the isolation of RNA, and evaluated for differentially expressed mRNAs by using gene microarrays. Bioarray data were analyzed with sophisticated bioinformatics and statistical programs. The expression of selected genes was verified by using gene chips and quantitative real-time PCR methods. The results demonstrate that 17beta-estradiol, progesterone, or both hormones together significantly influences the expression of hundreds of genes in the mouse lacrimal gland. Sex steroid treatment led to numerous alterations in gene activities related to transcriptional control, cell growth and/or maintenance, cell communication, signal transduction, enzyme catalysis, immune expression, and the binding and metabolism of nucleic acids and proteins. A number of the 17beta-estradiol, progesterone or 17beta-estradiol plus progesterone effects on gene expression were similar, but most were unique to each treatment. Of particular interest was the finding that these hormones seem to contribute little to the known sex-related differences in gene expression of the lacrimal gland. These results support the hypothesis that estrogen's and progesterone's action on the lacrimal gland involves the regulation of numerous genes. However, these hormone effects do not appear to represent a major factor underlying the sexual dimorphism of gene expression in lacrimal tissue.

Androgen regulation of gene expression in the mouse lacrimal gland

The objective of this study was to determine the nature and extent of androgen influence on gene expression in the lacrimal gland. Lacrimal glands were obtained from orchiectomized mice that had been treated with testosterone or vehicle for 2 weeks, as well as from testicular feminized mice and their Tabby controls. Samples were pooled according to experiment, processed for the isolation of RNA, and analyzed for differentially expressed mRNAs by using primarily CodeLink Bioarrays, GEM 1 and 2 gene chips and quantitative real-time PCR (qPCR) procedures. Gene chip data were analyzed with GeneSifter.Net software. Our results demonstrate that testosterone regulates the expression of over 2000 genes in the lacrimal gland. Gene ontologies most affected by androgen treatment included those related to cell growth, proliferation and metabolism, cell communication and transport, nucleic acid binding, signal transduction and receptor activities. Our findings also indicate that androgen action may be mediated, at least in part, through classical androgen receptors, and may contribute to the sex-related differences in gene expression of lacrimal tissue. Overall, these results support our working hypothesis that androgen action on the lacrimal gland is mediated primarily through a receptor-associated regulation of gene transcription.

Expression of TNF inhibitor gene in the lacrimal gland promotes recovery of tear production and tear stability and reduced immunopathology in rabbits with induced autoimmune dacryoadenitis

BackgroundThe most common cause of ocular morbidity in developed countries is dry eye, many cases of which are due to lacrimal insufficiency. Dry eye affects approximately 10 million in the United States., most of whom are women. In the U.S. alone, an estimated 2 million Sjögren's syndrome patients have dysfunctional lacrimal glands and severe dry eye, and there is no satisfactory treatment. These patients would benefit if their lacrimal tissue function could be restored.MethodsThe effect of adenovirus-mediated transfer of tumor necrosis factor (TNF)-α inhibitor gene on induced autoimmune dacryoadenitis was evaluated in a rabbit model. Soluble transgene protein was detected in tears by ELISA for 7 days following transduction.ResultsTwo weeks after induction of disease with activated lymphocytes, tear production, as determined by Schirmer testing, was reduced by about 40%, while tear film stability, as measured by tear breakup time (BUT), declined by 43%. Adenovirus-mediated gene therapy using AdTNFRp55-Ig given 2 weeks after disease induction, resulted in the return of tear production to normal levels by week 4. In the treated disease group, tear BUT improved significantly by week 4. Rose bengal scores, an indicator of corneal surface defects, increased after disease induction and declined after gene therapy. In the lacrimal gland, the CD4 to CD8 T cell ratio was 4:1 in the disease group compared to 1:2 in the treated group. Infiltration of T cells and CD18+ cells was reduced approximately 50% after gene therapy.ConclusionWe concluded that therapeutic levels of soluble TNF inhibitor were achieved in the lacrimal gland and on the corneal surface. Anti-inflammatory cytokine gene expression might offer a potential therapeutic modality for the treatment of autoimmune dacryoadenitis, once suitable vectors become available.

The role of eye‐associated lymphoid tissue in corneal immune protection

Because the cornea is optimized for refraction, it relies on supporting tissues for moistening and nutrition and in particular for immune protection. Its main support tissue is the conjunctiva, in addition to the lacrimal gland, the latter which provides soluble mediators via the tear film. The cornea and conjunctiva constitute a moist mucosal surface and there is increasing evidence that apart from innate defence mechanisms, also lymphoid cells contribute to the normal homeostasis of the corneal surface. A Medline-based literature search was performed in order to review the existing literature on the existence, composition and functions of mucosa-associated lymphoid tissue (MALT) at the ocular surface for corneal protection. The existence of lymphoid cells at the ocular surface and appendage has been known for many years, but for a long time they were believed erroneously to be inflammatory cells. More recent research has shown that in addition to the known presence of lymphoid cells in the lacrimal gland, they also form MALT in the conjunctiva as conjunctiva-associated lymphoid tissue (CALT) and in the lacrimal drainage system as lacrimal drainage-associated lymphoid tissue (LDALT). Together this constitutes an eye-associated lymphoid tissue (EALT), which is a new component of the mucosal immune system of the body. When the topographical distribution of CALT is projected onto the ocular surface, it overlies the cornea during eye closure and is hence in a suitable position to assist the corneal immune protection during blinking and overnight. It can detect corneal antigens and prime respective effector cells, or distribute protective factors as secretory IgA.

Bilateral Dacryops: Correlation of Clinical, Radiologic, and Histopathologic Features

Apostolos JT, Deshmukh M, Sanelli PC, Brazzo BG e report a case of bilateral lacrimal gland enlargement due to dacryops. Dedicated contrastenhanced CT of the orbits showed bilateral peripherally enhancing cystic structures that were contiguous with the palpebral lobes of the lacrimal glands. Histopathology confirmed the diagnosis of bilateral dacryops, an extremely rare clinical entity and even rarer bilaterally. Tears are produced by the lacrimal and accessory lacrimal glands and drain through the lacrimal ducts. Their function is to keep the ocular surface moist and clear of debris and bacteria. The major lacrimal glands are located at the anterior superolateral aspects of the orbits, adjacent to the tendons of the superior and lateral rectus muscles. The gland is separated into two lobes: the orbital and the palpebral [1]. Loss of lacrimal ductule contractility combined with distention of the duct wall results in a condition called “dacryops” [2]. Dacryops refers to a cyst of the lacrimal gland and can develop anywhere the lacrimal tissue is present. Cysts develop insidiously and present as painless masses on the eyelids. Their clinical presentation is rare, and their bilateral presentation is encountered even less frequently. We present the clinical, histopathologic, and CT appearance of bilateral dacryops as a unique case.

Different Effects on the Inflammatory Lesions in the Lacrimal and Salivary Glands after Neonatal Thymectomy in IQI/Jic Mice, a Model for Sjoegren's Syndrome

Thymectomy on day 3 after birth (D3Tx) is understood to eliminate CD4+CD25+ regulatory T cells (Treg) from the peripheral T cell repertoire in rodents, leading to the activation of autoreactive T cells. Herein, D3Tx was performed in IQI/Jic mice, a model for Sjögren's syndrome characterized by autoimmune infiltrations into the lacrimal and salivary glands. At the age of 16 weeks, very severe lesions were observed in lacrimal tissues from thymectomized mice, suggesting that Treg preserve their immunoregulatory function in young IQI/Jic mice. In contrast, salivary lesions were comparable in the D3Tx and control groups, raising the possibility that either salivary-specific Treg escaped elimination in thymectomized mice or spontaneous lesions in IQI/Jic mice developed independently of the tolerance through Treg.

Nasolacrimal obstruction secondary to I(131) therapy.

To report the finding of nasolacrimal drainage system obstruction associated with I(131) therapy for thyroid carcinoma from an updated and expanded cohort. Patients with a history of epithelial derived thyroid carcinoma who had tearing were offered referral for evaluation by an oculoplastic surgeon. Patients underwent nasolacrimal probing and irrigation procedures with localization of their nasolacrimal obstruction. Therapy for the site of obstruction was instituted. Clinically significant tearing was identified in 26 patients, all of whom had previously undergone I(131) therapy (n = 563). Nineteen patients were evaluated and confirmed to have nasolacrimal drainage system obstruction; 7 have yet to be formally evaluated. Areas of obstruction included nasolacrimal duct, common canaliculus, and, rarely, distal upper and lower canaliculi. Patients were treated with a variety of modalities including silicone intubation, balloon dacryoplasty, dacryocystorhinostomy, and conjunctival dacryocystorhinostomy. The use of I(131) for thyroid carcinoma is associated with a 3.4% incidence of documented nasolacrimal drainage obstruction and an overall 4.6% incidence of documented or suspected obstruction. The true incidence may be higher, since - I(131) treated individuals were neither systematically evaluated nor questioned about tearing. It has yet to be established if the obstructions result from local toxicity caused by the passive flow of radioactive iodine containing tears through these tissues or the active uptake and concentration of I(131) in lacrimal drainage system tissues through the sodium/iodide supporter.

ICAM-1 expression predisposes ocular tissues to immune-based inflammation in dry eye patients and Sjögrens syndrome-like MRL/lpr mice

Purpose. We previously reported that immune-based inflammation occurs on the ocular surface of humans as well as canines with keratoconjunctivitis sicca (KCS). Intercellular adhesion molecule-1 (ICAM-1) was found to be upregulated on lymphocytes and/or vascular endothelial cells resulting in lymphocytic diapedesis to the lacrimal and conjunctival tissues. The purpose of the current study was to demonstrate the role of ICAM-1 in (1) resident epithelial cell response during ocular inflammation, (2) local and/or peripheral lymphocyte activation or accumulation in the ocular tissues, and (3) whether anti-ICAM-1 is effective to attenuate immune-mediated ocular inflammation. Methods. ICAM-1 levels in various ocular tissues of human with KCS and/or MRL/lpr mouse were evaluated by immunohistochemistry and in situ hybridization for protein and messenger RNA (mRNA) expression, respectively. Soluble ICAM-1 concentrations in MRL/lpr mouse plasma over the course of disease development were measured by ELISA. Cell proliferation within ocular tissues was assessed by bromodeoxyuridine (BrdU) incorporation and immunohistochemical detection. The level of T cell activation was determined by IL-2 receptor (CD25, a marker of T cell activation and proliferation) and CD69 (a marker of T cell activation) immunoreactivity using FACS analysis. To examine the effectiveness of anti-ICAM-1/LFA-1 in elimination of lacrimal gland inflammation, MRL/lpr mice were injected intraperitoneally (i.p.) with or without monoclonal antibodies against ICAM-1 and LFA-1 at three or eight weeks of age. Results. Increased endogenous ICAM-1 expression at the level of protein and mRNA was detected in the epithelial cells present in the conjunctival and accessory lacrimal tissues in dry eye patients. In MRL/lpr mice, ICAM-1 expression by lacrimal acinar epithelial cells and conjunctival epithelial cells were detected in addition to inflammatory infiltrates and vascular endothelial cells at 16 weeks of age. Soluble ICAM-1 levels were markedly increased concomitantly with disease progression over time as compared with the controls. No significant lymphocytic proliferation (a lack of BrdU and CD25 immunoreactivities) was detected within lacrimal glands of MRL/lpr mice at the disease onset. However, a population of the infiltrated T cells were CD69 positive, indicating the activation stage of a T cell subset. Treatment using monoclonal antibodies against murine ICAM-1 and LFA-1 resulted in a decrease in the number of inflammatory infiltrates in MRL/lpr mice. Conclusions. Our findings suggest that ICAM-1 upregulation locally and systemically promote lymphocyte activation and migration to the ocular surface (OS). Ocular resident epithelium is an active component of ocular surface and is capable of interacting with invasive lymphocytes by ICAM-1 production in response to immune activation and inflammation. ICAM-1 synthesized by epithelial cells may serve as a signaling molecule for predisposition of ocular surface inflammation and facilitate potential antigen presentation by epithelial cells. Lymphocytic infiltrates in the lacrimal gland of the MRL/lpr mouse appeared to be the result of the accumulation, but not proliferation of circulating lymphocytes diapodesed from the vasculature that had migrated into the local ocular tissues. The potential use of anti-ICAM-1 therapy in treating immune-based inflammatory diseases such as dry eye deserves further investigation.

Lacrimal gland as the major source of mouse tear factors that are cytotoxic to corneal keratocytes

We have previously shown that mouse tears are cytotoxic to the corneal keratocytes. Since tear components are derived from both lacrimal tissues and ocular surface epithelium, we sought to determine the source of the cytotoxic factors in the mouse tear fluid. Cytotoxicity to keratocytes was assessed by an ex vivo assay using an isolated eye; after treatment with test samples, segmentation and disappearance of stromal nuclei were determined by DAPI nuclear staining. Following biological tissues and fluids were examined either directly or after preincubation at 37°C for 2–15 hr: extraorbital lacrimal gland (ELG), intraorbital lacrimal gland (ILG), Harderian gland, Meibomian gland, corneal epithelium, bulbar conjunctiva, palpebral conjunctiva, serum, aqueous humor, and lacrimal fluid collected from a secretory duct of ELG. Under the ex vivo assay conditions, ELG and ILG, with or without preincubation, exhibited a cytotoxic effect comparable to that of diluted tears. Lacrimal fluid collected from an ELG duct was similarly effective. These specimens triggered nuclear segmentation that is typical of apoptotic nuclei. All other specimens showed no effect on stromal nuclei under the identical conditions. In some animals, ELG was surgically removed and the tear cytotoxicity was examined in vivo. The tear cytotoxicity in these animals was lost after the surgery, indicating an involvement of ELG, but it was restored 4–24 hr afterward, suggesting a compensatory role of ILG. These results suggest that ELG and ILG are the major sources of tear factors that are cytotoxic to the keratocytes in the mouse.

Identification of androgen-regulated genes in the lacrimal gland.

Androgens exert a significant influence on the cellular architecture, protein synthesis, immune function and secretory activity of the lacrimal gland.1 In fact, these hormone effects appear to account for many of the gender-related differences that occur in the anatomy, biochemistry, physiology and immunology of lacrimal tissue in a variety of species.1 We hypothesize that androgen actions are mediated primarily through androgen receptors, which exist in lacrimal gland epithelial cells,2–4 and involve the regulation of specific target genes. The purpose of this investigation was to identify the genes controlled by androgens in lacrimal tissue.

The role of ICAM-1 as a signal protein for predisposition of ocular surface inflammation.

Recent research in our laboratory and others has demonstrated keratoconjunctivitis sicca (KCS, dry eye) is caused by an autoimmune inflammatory process affecting the lacrimal “functional unit”. This is composed of the lacrimal glands (main and accessory), ocular surface and interconnecting innervation. The histological hallmark of this disease, regardless if an individual is diagnosed with systemic autoimmune syndrome or is subject to a local autoimmune event, is an immune cell infiltration of the lacrimal glands (main and accessory) as well as the conjunctival substantia propria and epithelium. The infiltrating cells are typically CD4-positive T-helper cells. They target the tissues in response to a local epithelial antigen presentation resulting from a neurogenic inflammation of the lacrimal glands and ocular tissues. This inflammation is facilitated by an age-related (menopause) or treatment-related (anti-androgen therapy) loss of circulating androgens in the affected tissues. The purpose of this study was to evaluate mouse models of autoimmunity to investigate initiation of the observed lacrimal gland and ocular surface inflammation and determine the role of ICAM-1 in the pathophysiology of dry eye.

Human lacrimal drainage-associated lymphoid tissue (LDALT) belongs to the common mucosal immune system.

The lacrimal drainage system constitutes the part of the ocular adnexa where the tear flow drains after production in the lacrimal gland and subsequent to bathing the ocular surface. It is lined by a mucosa that continues that of the conjunctiva. The lacrimal drainage system begins at the two lacrimal puncta of the lid margin that lead via the lacrimal canaliculi into the cavernous lacrimal sac and via the nasolacrimal duct into the nose (Fig. 1).

The role of bacteriologic infection in the etiology of nasolacrimal duct obstruction

Background: In patients with nasolacrimal duct obstruction, the inflammation and fibrosis may be secondary to coexisting infectious colonization within the lumen of the lacrimal sac. We examined the bacterial flora within the lacrimal sac at the sac-duct junction to explore the possibility of a primary bacteriologic etiology of the inflammatory response.Methods: The study included 114 consecutive patients (132 sides) with epiphora undergoing routine external dacryocystorhinostomy (DCR) at a tertiary care hospital in Toronto between November 1999 and April 2000. A lacrimal sac tissue biopsy specimen was acquired intraoperatively from the inferior posterior lacrimal sac near the sac-duct junction. Microbiologic analysis was carried out to determine the presence and identification of infectious organisms.Results: Culture gave positive results in 51 patients (44.7%) (41.7% of specimens). A total of 65 isolates were cultured, of which 78.5% were gram-positive bacteria and 21.5% gram-negative bacteria. Of the gram-positive organisms 76.5% were Staphylococcus sp. The presence of a positive culture result was independent of a history of dacryocystitis or the presence of a mucocele.Interpretation: Using direct biopsy methods, we found culture-positive lacrimal sac specimens in a large proportion of patients undergoing DCR surgery. These organisms were found to be present in patients with and without a history of infection.

The pathogenesis and treatment of lacrimal obstruction: The value of lacrimal sac and bone analysis

INTRODUCTION . The cause of primary acquired nasolacrimal duct obstruction (NLDO) has not been fully elucidated. In an attempt to determine the role of an inflammatory etiology, the pathology of nasolacrimal sac and bone specimens was assessed and correlated with clinical lacrimal variables. MATERIALS AND METHODS . Lacrimal sac and bone tissues from patients with known NLDO were sampled at the time of external dacryocystorhinostomy (DCR). Histopathological analysis was carried out to determine the presence and degree of inflammatory changes present in the tissues, and to correlate them with the clinical presentation. RESULTS . Of 104 cases analyzed, bony inflammatory changes were seen in 14% and lacrimal sac inflammatory changes in 94%. All cases of bony inflammation had accompanying lacrimal sac inflammation. The inflammatory changes were independent of the following variables: gender, duration of symptoms, a history of dacryocystitis, the presence of a lacrimal sac mucocele, the location of obstruction, and the presence of lacrimal sac calculi. CONCLUSIONS . Inflammatory changes are almost invariably present in all patients with NLDO. Its occurrence in bone is probably secondary to lacrimal sac inflammation. Although attempts are made to perform DCR surgery only in the absence of lacrimal sac inflammation, almost all cases exhibit subclinical inflammation. This may suggest that bypassing this ‘critical area’ of the sac-duct junction, as in a dacryocystorhinostomy, would be more reasonable than to re-canalize through an inflammatory obstruction.

IDENTIFICATION OF ANDROGEN-REGULATED GENES IN THE LACRIMAL GLAND.

Androgens exert a significant influence on the cellular architecture, protein synthesis, immune function and secretory activity of the lacrimal gland.1 In fact, these hormone effects appear to account for many of the gender-related differences that occur in the anatomy, biochemistry, physiology and immunology of lacrimal tissue in a variety of species.1 We hypothesize that androgen actions are mediated primarily through androgen receptors, which exist in lacrimal gland epithelial cells,2–4 and involve the regulation of specific target genes. The purpose of this investigation was to identify the genes controlled by androgens in lacrimal tissue.

THE ROLE OF ICAM-1 AS A SIGNAL PROTEIN FOR PREDISPOSITION OF OCULAR SURFACE INFLAMMATION.

Recent research in our laboratory and others has demonstrated keratoconjunctivitis sicca (KCS, dry eye) is caused by an autoimmune inflammatory process affecting the lacrimal “functional unit”. This is composed of the lacrimal glands (main and accessory), ocular surface and interconnecting innervation. The histological hallmark of this disease, regardless if an individual is diagnosed with systemic autoimmune syndrome or is subject to a local autoimmune event, is an immune cell infiltration of the lacrimal glands (main and accessory) as well as the conjunctival substantia propria and epithelium. The infiltrating cells are typically CD4-positive T-helper cells. They target the tissues in response to a local epithelial antigen presentation resulting from a neurogenic inflammation of the lacrimal glands and ocular tissues. This inflammation is facilitated by an age-related (menopause) or treatment-related (anti-androgen therapy) loss of circulating androgens in the affected tissues. The purpose of this study was to evaluate mouse models of autoimmunity to investigate initiation of the observed lacrimal gland and ocular surface inflammation and determine the role of ICAM-1 in the pathophysiology of dry eye.

Differential Regulation of Rat Aquaporin-5 Promoter/Enhancer Activities in Lung and Salivary Epithelial Cells

Aquaporin-5 (AQP5) is a water channel protein that is selectively expressed in respiratory, salivary, and lacrimal tissues. In order to establish the tissue-specific transcriptional programs that underlie its lung- and salivary-specific expression, a 4.5-kilobase pair DNA fragment encompassing the 5'-flanking region of the rat AQP5 gene has been characterized in detail. A major transcription start site utilized in lung and salivary glands has been localized downstream of a TATAA-like motif. Transient transfection assays of -4.3- and -1.7-AQP5-luciferase constructs in AQP5-expressing lung (MLE-15) and salivary (Pa-4) cells and nonexpressing fibroblast (NIH3T3) and epithelial (HeLa) cells demonstrate preferential transcriptional enhancement of reporter activities in MLE-15 and Pa-4 cells. Transient transfection assays of a series of 5' --> 3' deletion constructs of -4.3-AQP5-luciferase suggest that a common salivary and lung enhancer is located between nucleotides -274 and -139, and a lung-specific enhancer is located between nucleotides -894 and -710. There is one putative lung-specific repressor located in the region of nucleotides -1003/-894 and a common lung and salivary repressor located at nucleotides -503/-385. Moreover, 3' --> 5' deletions up to -171 and -127 base pairs almost abolish transcriptional activation in salivary and lung cells, respectively. Together, our findings indicate that the combination of enhancer/repressor elements within the proximal 5'-flanking region of rat AQP5 gene dictates its restricted expression in both lung and salivary cells.

Gender- and androgen-related influence on the expression of proto-oncogene and apoptotic factor mRNAS in lacrimal glands of autoimmune and non-autoimmune mice

Our previous studies have shown that the mRNA levels of c-myb, c-myc, bcl-2 and p53 are higher, and partial Fas antigen (i.e. exons 1–2) lower, in lacrimal tissues of female, as compared to male, MRL/lpr mice, which are a model of Sjögren's syndrome. We have also found that this gender-related difference in bcl-2 and c-myb expression appears to be due to the influence of androgens. To extend these findings, we sought to determine: first, whether these gender- and/or hormone-associated variations in mRNA content are unique to MRL/lpr mice, or are also present in lacrimal glands of other murine strains, including autoimmune NZB/NZW F1 (F1) and non-obese diabetic (NOD), as well as non-autoimmune C3H/HeJ (C3H) and BALB/c, mice; and second, whether the levels of these apoptotic factor mRNAs are altered in lacrimal tissues of mice (i.e. testicular feminized (Tfm) with dysfunctional androgen receptors, as compared to glandular amounts in their ‘normal’ controls (i.e. Tabby). Lacrimal tissues were obtained from adult mice, which were either untreated or treated with placebo or testosterone for 21 days. Glands were processed for the analysis of proto-oncogene mRNAs by RT-PCR (at exponential phase of amplification) and data were standardized to the corresponding levels of β-actin mRNA. Our results demonstrate that Fas antigen, Fas ligand, c-myb, c-myc, bcl-2, Bax and p53 mRNAs are present in lacrimal tissues of F1, NOD, C3H, BALB/c, Tabby and Tfm mice. The relative levels of Fas antigen mRNA are consistently higher in glands of males, whereas amounts of bcl-2 mRNA are greater in tissues of F1, C3H and BALB/c females. Testosterone administration induced a significant increase in the lacrimal gland content of Bax mRNA, but a striking decrease in the lacrimal tissue level of bcl-2 mRNA in F1 and C3H mice. Lacrimal glands of Tfm mice contained elevated amounts of bcl-2 mRNA, as compared to values in tissues of their Tabby controls. In summary, our findings show that fundamental gender-related differences exist in the expression of genes associated with programmed cell death in lacrimal glands of autoimmune and normal mice. In addition, some of these differences may be due, at least in part, to the effect of androgens.

Ectopic gland induction by lens-specific expression of keratinocyte growth factor (FGF-7) in transgenic mice

During mammalian embryogenesis, epithelial-mesenchymal interactions play a determining role in normal tissue patterning and development. Keratinocyte growth factor (KGF), a member of the fibroblast growth factor (FGF) family, is a mesenchymally-derived mitogen for epithelial cells. As the KGF receptor is expressed by epithelial cells of numerous tissues and KGF is produced in adjacent stromal cells, KGF is thought to play a role in mediating epithelial cell behaviour. To further investigate the role of this molecule in the development of ocular epithelia we employed transgenic mice engineered to overexpress human KGF in the eye. The most striking phenotypic development was the hyperproliferation of embryonic corneal epithelial cells and their subsequent differentiation into functional lacrimal gland-like tissues. This indicates that stimulation of the KGF receptor early in development, in surface ectoderm normally destined to form corneal epithelium, is sufficient to alter the fate of these cells. Furthermore, this suggests that the correct spatial and temporal expression of FGFs plays a critical role in normal lacrimal gland induction. These transgenic mice provide a valuable model system to study the mechanisms underlying cell fate decisions during ocular morphogenesis.