Lacrimal gland epithelial cells stimulate proliferation in autologous lymphocyte preparations

Establishing human lacrimal gland cultures from biopsy-sized tissue specimens

OBJECTIVES

To establish cultures of human lacrimal gland from patient-derived, biopsy-sized, tissue specimens.

METHODS

Tissue was obtained after surgical removal from patients without dry eye disease undergoing routine procedures. Samples were subjected to mechanical and enzymatic digestion and resulting cell suspensions were plated onto collagen-coated glass coverslips and grown for up to 21 days. Cultures were analysed by immunocytochemistry and light microscopy, and resultant cellular distributions were compared to those in sections of fixed human lacrimal gland tissue.

RESULTS

Dissociation of biopsy-sized pieces of human lacrimal gland and seeding onto coated surfaces allowed development of a mixed population of cells in vitro. Within 7-14 days, cellular aggregation was observed and by 21 days many cells had organised themselves into distinct three-dimensional complexes. Immunohistochemistry revealed a heterogeneous population of cells, including epithelial, myoepithelial, mesenchymal and progenitor cells. Some of the epithelia labelled positively for lysozyme and lactoferrin.

CONCLUSIONS

Collection and dissociation of biopsy-sized pieces of human lacrimal gland leads to a cellular preparation that can proliferate in vitro and organise into three-dimensional structures. This is the first report detailing that biopsy-collected specimens of human lacrimal gland can be used to establish cell cultures.

Supra-lacrimal protein-based carriers for cyclosporine A reduce Th17-mediated autoimmunity in murine model of Sjögren's syndrome

Sjögren's syndrome (SS) is a multifactorial autoimmune disease with principal symptoms including inflammation and loss of function of lacrimal glands (LG) and salivary glands. While glandular infiltrates includes both B- and T-cells, CD4+ T cells are strongly implicated. Utilizing the male non-obese diabetic (NOD) mouse model of SS, this work: 1) identifies clinically-relevant elevations in cytokines (IL-17A, IL-2) in LG-derived CD4+ T cells; and 2) explores tissue-specific immunosuppression of SS using a novel protein-based drug carrier to concentrate cyclosporine A (CsA) directly in the LG. As a potent immunosuppressant, topical ophthalmic CsA is approved for dry eye disorders; however, it cannot effectively resolve inflammation due to limited accumulation in the LG. Systemic CsA has dose-limiting side effects that also limit its ability to block LG inflammation. Using elastin-like polypeptides (ELPs) fused genetically to cyclophilin, the intracellular cognate receptor of CsA, this manuscript reports a sustained-release formulation of CsA that maintains therapeutic drug concentrations in the LG and extends intervals between doses. This formulation blocked both in vitro Th17 cell differentiation and IL-17A secretion. In vivo treatment significantly decreased the abundance of Th17.1 cells, a helper cell population sharing phenotypes of both Th17 and Th1, in the LG of diseased NOD mice. Treatment with even a single dose of the sustained-release formulation was effective enough to improve basal levels of tear production. Thus, this sustained-release formulation suppressed local LG inflammation driven through IL-17 dependent pathways, while improving ocular surface function.

Human umbilical cord mesenchymal stem cells alleviate ongoing autoimmune dacryoadenitis in rabbits via polarizing macrophages into an anti-inflammatory phenotype

Mesenchymal stem cells (MSCs) exhibit beneficial effects on autoimmune dacryoadenitis. However, the underlying mechanisms are not fully understood. In this study, we investigated the therapeutic effect of human umbilical cord mesenchymal stem cells (hUC-MSCs) on rabbit autoimmune dacryoadenitis, an animal model of Sjögren's syndrome (SS) dry eye, and explored whether the effects of MSCs were related to their modulation on macrophage polarization. We have showed that systemic infusion of hUC-MSCs after disease onset efficiently diminished the chronic inflammation in diseased LGs and improved the clinical symptoms. Further analysis revealed that hUC-MSC treatment significantly inhibited the expression of pro-inflammatory M1 macrophage markers iNOS, TNF-α and IL-6, and promoted the expression of anti-inflammatory M2 macrophage markers Arg1, CD206, IL-10, IL-4 and TGF-β in LGs. Mechanistically, hUC-MSCs activated AKT pathway in macrophages, resulting in upregulation of M2-associated molecule Arg1, which was partly abolished by PI3K inhibitor, LY294002. Together, our data indicated that hUC-MSCs can skew macrophages into an M2 phenotype via affecting AKT pathway. These data may provide a new insight into the mechanisms of hUC-MSCs in the therapy of SS dry eye.

Berunda Polypeptides: Biheaded Rapamycin Carriers for Subcutaneous Treatment of Autoimmune Dry Eye Disease

The USFDA-approved immunosuppressive drug rapamycin (Rapa), despite its potency, is limited by poor bioavailability and a narrow therapeutic index. In this study, we sought to improve bioavailability of Rapa with subcutaneous (SC) administration and to test its therapeutic feasibility and practicality in a murine model of Sjögren's syndrome (SS), a systemic autoimmune disease with no approved therapies. To improve its therapeutic index, we formulated Rapa with a carrier termed FAF, a fusion of the human cytosolic FK506-binding protein 12 (FKBP12) and an elastin-like polypeptide (ELP). The resulting 97 kDa FAF (i) has minimal burst release, (ii) is "humanized", (iii) is biodegradable, (iv) solubilizes two Rapa per FAF, and (v) avoids organic solvents or amphiphilic carriers. Demonstrating high stability, FAF remained soluble and monodisperse with a hydrodynamic radius of 8 nm at physiological temperature. A complete pharmacokinetic (PK) analysis of FAF revealed that the bioavailability of SC FAF was 60%, with significantly higher blood concentration during the elimination phase compared to IV FAF. The plasma concentration of Rapa delivered by FAF was 8-fold higher with a significantly increased plasma-to-whole blood ratio relative to free Rapa, 24 h after injection. To evaluate therapeutic effects, FAF-Rapa was administered SC every other day for 2 weeks to male non-obese diabetic (NOD) mice, which develop an SS-like autoimmune-mediated lacrimal gland (LG) inflammation and other characteristic features of SS. Both FAF-Rapa and free Rapa exhibited immunomodulatory effects by significantly suppressing lymphocytic infiltration, gene expression of IFN-γ, MHC II, type I collagen and IL-12a, and cathepsin S (CTSS) activity in LG compared to controls. Serum chemistry and histopathological analyses in major organs revealed no apparent toxicity of FAF-Rapa. Given its improved PK and equipotent therapeutic efficacy compared to free Rapa, FAF-Rapa is of further interest for systemic treatments for autoimmune diseases like SS.

Adipose-Derived Mesenchymal Stem Cells Reduce Lymphocytic Infiltration in a Rabbit Model of Induced Autoimmune Dacryoadenitis

Purpose

To investigate the immunoregulatory roles of adipose-derived mesenchymal stem cells (ADSCs) in autoimmune dacryoadenitis.

Methods

Rabbits were treated with ADSCs or phosphate-buffered solution on days 1, 3, 5, 7, and 9 after injection of activated peripheral blood lymphocytes, and clinical scores were determined by assessing tear production, break-up time, and fluorescein and hematoxylin and eosin staining. Inflammatory response was determined by measuring the expression of different mediators of inflammation in the lacrimal glands. The Th1/Th17-mediated autoreactive responses were evaluated by determining the proliferative response and the expression of cytokine genes and the lineage-determining transcription factors. The frequency of regulatory T cells (Tregs) was also examined.

Results

The ADSC-treated rabbits showed decreased autoimmune responses, and the secretory function of their lacrimal gland was restored significantly. Treatment with ADSCs downregulated the Th1 and Th17 responses but enhanced Tregs function. In addition, ADSC treatment noticeably suppressed the expression of matrix metalloproteinase (MMP)-9, MPP-2, IL-1β, and IL-6, whereas it enhanced the expression of the anti-inflammatory cytokine IL-10.

Conclusions

Our results demonstrated that ADSC administration efficiently ameliorates autoimmune dacryoadenitis mainly via modulating Th1/Th17 responses.

Multiple Natural and Experimental Inflammatory Rabbit Lacrimal Gland Phenotypes

Purpose

To investigate lacrimal gland (LG) immunophysiological and immune-mediated inflammatory process (IMIP) phenotype diversity.

Methods

Ex vivo matured dendritic cells (mDC) were loaded with acinar cell microparticles (M_P). Peripheral blood lymphocytes (PBL) were activated in mixed cell reactions with mDC and injected directly into autologous, unilateral LG (1° ATD-LG) of two rabbit cohorts, one naïve, one immunized with a LG lysate membrane fraction (P_i). Autoimmune IgG titers were assayed by ELISA, MCR PBL stimulation indices (SI) by [³H]-thymidine incorporation. Schirmer tests without and with topical anesthetic (STT-I, STT-I_A) and rose Bengal (RB) staining tests were performed. H&E and immunohistochemically stained sections were examined. RNA yields and selected transcript abundances were measured. Immune cell number and transcript abundance data were submitted to Principal Component Analysis (PCA).

Results

Immunizing P_i dose influenced SI but not IgG titers. STT scores were decreased, and rose Bengal scores increased, by day 118 after immunization. Previous immunization exacerbated scores in 1° ATD-eyes and exacerbated 1° ATD-LG atrophy. IMIP were evident in 2° ATD-LG as well as 1° ATD-LG. PCA described diverse immunophysiological phenotypes in control LG and diverse IMIP phenotypes in ATD-LG. IgG titers and SI pre-adoptive transfer were significantly associated with certain post-adoptive transfer IMIP phenotype features, and certain LG IMIP features were significantly associated with RB and STT I_A scores.

Conclusions

The underlying variability of normal states may contribute to the diversity of experimental IMIP phenotypes. The ability to generate and characterize diverse phenotypes may lead to phenotype-specific diagnostic and therapeutic paradigms.

Engineering of a Secretory Active Three-Dimensional Lacrimal Gland Construct on the Basis of Decellularized Lacrimal Gland Tissue

Lacrimal gland (LG) insufficiency is a main cause for severe dry eye leading to pain, visual impairment, and eventually loss of sight. Engineering of transplantable LG tissue with secretory capacity is a desirable goal. In this study, a three-dimensional decellularized LG (DC-LG) scaffold with preserved LG morphology was generated by treatment with 1% sodium deoxycholate and DNase solution using porcine LG tissue. To address clinical applicability, the primary in vitro culture of secretory active LG cells from a small tissue biopsy of 1.5 mm diameter was introduced and compared with an established isolation method by enzymatic digestion. Cells from both isolation methods depicted an epithelial phenotype, maintained their secretory capacity for up to 30 days, and exhibited progenitor cell capacity as measured by aldehyde dehydrogenase-1 activity, side population assay, and colony-forming units. Cells from passage 0 were reseeded into the DC-LG and secretory active cells migrated into the tissue. The cells resembled an LG-like morphology and the constructs showed secretory activity. These results demonstrate the possibility of engineering a secretory competent, three-dimensional LG construct using LG cells expanded from a small tissue biopsy and DC-LG as a matrix that provides the native structure and physiological niche for these cells.

Proteomic analysis revealed the altered tear protein profile in a rabbit model of Sjögren's syndrome-associated dry eye

Sjögren's syndrome (SS) is an autoimmune disease that results in pathological dryness of mouth and eye. The diagnosis of SS depends on both clinical evaluation and specific antibodies. The goal of this study was to use quantitative proteomics to investigate changes in tear proteins in a rabbit model of SS-associated dry eye, induced autoimmune dacryoadenitis (IAD). Proteomic analysis was performed by iTRAQ and nano LC-MS/MS on tears collected from the ocular surface, and specific proteins were verified by high resolution MRM. It was found that in the tears of IAD rabbits at 2 and 4 weeks after induction, S100 A6, S100 A9, and serum albumin were upregulated, whereas serotransferrin (TF), prolactin-inducible protein (PIP), polymeric immunoglobulin receptor (pIgR), and Ig gamma chain C region were downregulated. High resolution MRM with mTRAQ labeling verified the changes in S100 A6, TF, PIP, and pIgR. Our results indicated significant changes of tear proteins in IAD rabbits, suggesting these proteins could potentially be used as biomarkers for the diagnosis and prognosis of dry eye. Several of these proteins were also found in the tears of non-SS dry eye patients indicating a common basis of ocular surface pathology, however, pIgR appears to be unique to SS.

Autoimmune dacryoadenitis and sialadenitis induced in rabbits by intravenous injection of autologous lymphocytes activated ex vivo against lacrimal antigens

PURPOSE

Autologous peripheral blood lymphocytes, activated in a mixed cell reaction when cocultured with purified rabbit lacrimal epithelial cells, are known to induce a severe autoimmune dacryoadenitis when injected directly into the donor animal's remaining inferior lacrimal gland (LG) or subcutaneously at a site remote from the LG. The purpose of the present study was to determine the ability of intravenously (IV) injected autologous stimulated lymphocytes to home to the LG and salivary gland (SG) and induce disease.

METHODS

One inferior LG was surgically excised from each rabbit. Acinar epithelial cells were purified, cultured for 2 days, gamma-irradiated, and cocultured for 5 days with purified autologous peripheral blood lymphocytes. The activated lymphocytes were used for autoadoptive transfer.

RESULTS

Tear production was reduced 50% by 4 weeks and tear breakup time was 70% less than normal. Ocular surface defects assessed by rose bengal staining were present but not as pronounced as after direct injection. Four weeks after IV injection, as after direct injection, glands contained large infiltrates composed of predominantly CD4(+) T cells close to interlobular and intralobular ducts; however, they also contained unique areas of streaming lymphocytes. Histopathology at 8 weeks was more severe than at 4 weeks, and SG also showed clusters of abnormal epithelial cells and streaming lymphocytes.

CONCLUSIONS

Lymphocytes activated against lacrimal antigens and injected IV can home to the LG and SG and initiate autoimmune processes, suggesting that these sites constitutively contain not only antigen-presenting cells displaying potentially pathogenic autoantigen epitopes but also chemokines and homing molecules that recruit CD4(+) T cells. This new rabbit model more closely mimics Sjögren syndrome, in that SG manifestations accompany the LG disease. It should be well suited to elucidating Sjögren pathogenesis and pathophysiology and to evaluating experimental therapies.

A Rab11a-enriched subapical membrane compartment regulates a cytoskeleton-dependent transcytotic pathway in secretory epithelial cells of the lacrimal gland

Despite observations that the lacrimal gland has been identified as the principal source of dimeric immunoglobulin A (dIgA) in tears, the mechanism used by lacrimal gland acinar cells (LGACs) to transcytose dIgA produced by interstitial plasma cells is not well-characterized. This study identifies a transcytotic pathway in LGACs regulated by Rab11a for polymeric immunoglobulin receptor (pIgR) and dIgA. EGFP-tagged Rab11a expressed in primary LGACs labeled a unique membrane compartment of comparable localization to endogenous Rab11a beneath the apical plasma membrane. This compartment was enriched in pIgR and clearly distinct from the regulated secretory pathway. Comparison of dIgA uptake in LGACs expressing wild type and dominant negative EGFP-Rab11a showed that the rapid exocytosis of dIgA was inhibited in acini expressing the dominant-negative protein, which additionally redistributed subapical pIgR. The trafficking of EGFP-Rab11a-enriched vesicles was regulated by microtubule-based and myosin Vb motors at distinct steps. Our data suggest that Rab11a is a crucial regulator of dIgA trafficking in primary acinar secretory epithelial cells and further support a role for microtubules, cytoplasmic dynein, actin filaments and myosin Vb in the maintenance of the Rab11a compartment in this primary secretory epithelial cell.

Distinct dacryoadenitides autoadoptively transferred to rabbits by different subpopulations of lymphocytes activated ex vivo

PURPOSE

To test whether CD4+ T cells proliferate in mixed cell reactions with autologous lacrimal gland (LG) acinar cells and whether these cells can autoadoptively transfer disease.

METHODS

Purified acinar cells were gamma irradiated and cocultured with peripheral blood lymphocytes. Activated CD4+ T cells were sorted by fluorescence-activated cell sorting (FACS). Unfractionated activated peripheral blood lymphocytes (UF), CD4+-enriched and CD4+-depleted T cells from an autologous mixed cell reaction were injected into the donor rabbit's remaining LG. After 4 weeks, ocular examinations were performed, and the rabbits were euthanized; LGs were removed for histopathology, immunohistochemistry, and real-time reverse transcription-polymerase chain reaction studies.

RESULTS

CD4 T cells increased in the autologous mixed cell reaction from 20% to 80%. Tear production decreased in the induced disease/UF (ID/UF) group and declined even more in the ID/CD4+-enriched group. Tear breakup times decreased and rose bengal staining increased in all groups. All LGs exhibited significant histopathology and increased messenger RNAs for tumor necrosis factor α. The ID/UF group exhibited the largest increases of CD4+ and rabbit T-lymphocyte antigen-positive cells. The ID/CD4+-enriched group contained fewer infiltrating CD4 cells but more eosinophils, severely altered acinar morphology, and increased fibrosis. LG of the ID/CD4+-depleted group exhibited large increases of CD18, major histocompatibility complex II, and CD4+ cells. Messenger RNAs for interleukin 2, interleukin 4, and CD4+ increased in the ID/CD4+-enriched group compared with the CD4+-depleted group.

CONCLUSIONS

Autoreactive CD4+ effector cells activated ex vivo and autoadoptively transferred, caused what seems to be a distinct dacryoadenitis. The CD4+-depleted cell fraction also contained pathogenic effector cells capable of inducing disease.

Adeno-associated virus-mediated IL-10 gene transfer suppresses lacrimal gland immunopathology in a rabbit model of autoimmune dacryoadenitis

PURPOSE

To evaluate the effect of adeno-associated virus (AAV) vector-mediated viral (v)IL-10 gene expression on lacrimal gland (LG) immunopathology and ocular surface disease in a rabbit model of induced autoimmune dacryoadenitis (ID).

METHODS

Autologous peripheral blood lymphocytes, activated in a mixed-cell reaction when cocultured with purified rabbit lacrimal epithelial cells, induce a Sjögren's-like autoimmune dacryoadenitis when injected directly back into the donor animal's inferior LG. Four weeks after disease induction, AAV vector expressing the vIL-10 gene under control of a tetracycline-inducible promoter was injected into the inferior LG of the treatment group (ID/Rx), and doxycycline was fed orally to induce transgene expression. The ID group serving as control also received doxycycline. All LGs were removed 16 weeks after disease induction.

RESULTS

Clinical symptoms showed overall improvement in the ID/Rx group compared with the ID group. Histopathologic examination of the ID group's LG revealed scattered large lymphocytic foci and areas of altered or distorted acini, whereas the ID/Rx group had scattered small lymphocytic foci. The number of CD18(+) cells was almost fivefold lower in the ID/Rx group than in the ID group. Although the total number of RTLA(+) cells did not differ between the groups, the CD4/CD8 ratio was 16-fold smaller in the ID/Rx group.

CONCLUSIONS

Animals with experimentally induced autoimmune dacryoadenitis appeared to benefit from AAV-mediated vIL-10 gene transfer therapy. Quantitative immunohistochemical analysis suggested that the therapy might not have been simply immunosuppressive but rather supported the induction of CD8(+) regulatory cells.

Lymphocytic infiltration leads to degradation of lacrimal gland extracellular matrix structures in NOD mice exhibiting a Sjögren's syndrome-like exocrinopathy

We previously reported that lacrimal glands (LGs) of male non-obese diabetic (NOD) mice, an established mouse model of autoimmune inflammatory LG disease that displays many features of human LGs in patients afflicted with Sjögren's syndrome (SjS), exhibit significant degradation of extracellular matrix (ECM) structures as well as increased expression of matrix metalloproteinases (MMPs). The purpose of the current study was to expand the spectrum of proteases identified, to clarify their probable origin as well as to identify the contribution of these changes to disease pathogenesis. We explored in depth the changes in ECM structures and ECM protease expression at the onset of disease (6 weeks) versus late stage disease (18 weeks) in male NOD mouse LGs, relative to LGs of age-matched male NODscid, a severely immunocompromised congenic strain, and healthy BALB/c mice. LG tissues were examined using routine histological, immunohistochemical, Western Blot and gene expression analyses novel multiphoton imaging technologies. We further characterized the profile of infiltrating immune cells under each condition using flow cytometry. Our results show that the initial infiltrating cells at 6 weeks of age are responsible for increased MMP and cathepsin H expression and therefore initiate the LG ECM degradation in NOD mice. More importantly, NODscid mice exhibited normal LG ECM structures, indicating the lymphocytes seen in the LGs of NOD mice are responsible for the degradation of the LG ECM. The disease-related remodeling of LG ECM structures may play a crucial role in altering the acinar signaling environment, disrupting the signaling scaffolds within the cells, which are required to mobilize the exocytotic trafficking machinery, ultimately leading to a loss of LG function in patients afflicted with SjS.

Suppression of lymphocyte proliferation and regulation of dendritic cell phenotype by soluble mediators from rat lacrimal epithelial cells

Lacrimal epithelial cells appear to constitutively secrete autoantigens to their underling stroma. The present experiments address the hypothesis that they also secrete soluble factors that regulate immune responses. Epithelial cells, spleen cells and lymphocytes were obtained from rabbits or rats and cultured in various configurations. Monocytes from rat bone marrow were matured to dendritic cells (DC) ex vivo. Proliferation was measured by [3H]-thymidine incorporation; surface MHC Class II and CD86 using flow cytometry; and mRNA relative abundances using real time RT-PCR. Microporous culture inserts containing rat lacrimal cells inhibited proliferation of rabbit lymphocytes co-cultured with autologous lacrimal cells and of rat lymphocytes co-cultured with TNF-alpha-stimulated DC. They inhibited CD86 and MHC Class II surface expression by maturating DC and reversed surface expression of CD86 but not MHC Class II by partially matured DC. Subsequent exposure of partially matured DC to mediators from rat lacrimal cells reversed the ability to stimulate lymphocyte proliferation. TGF-beta(1) and IL-10 mRNAs increased somewhat when rat lacrimal cells were isolated but decreased markedly in rabbit lacrimal cells. Antibodies to TGF-beta prevented soluble factors from rat lacrimal cells from inhibiting proliferation of rabbit lymphocytes co-cultured with rabbit lacrimal cells, but recombinant TGF-beta alone did not mimic the soluble factors. IL-10 immunopositivity was detected in epithelial cells of interlobular ducts and occasional interstitial cells in rabbit lacrimal gland. Rat lacrimal epithelial cells secrete TGF-beta and other factors that synergize to suppress lymphocyte proliferation and regulate DC maturation. Interlobular duct epithelial cells in rabbit lacrimal glands may express similar functions.

Autoimmune dacryoadenitis and keratoconjunctivitis induced in rabbits by subcutaneous injection of autologous lymphocytes activated ex vivo against lacrimal antigens

Autologous peripheral blood lymphocytes (PBL), activated in a mixed cell reaction when co-cultured with purified rabbit lacrimal epithelial cells, are known to induce a Sjögren's-like autoimmune dacryoadenitis and keratoconjunctivitis when injected directly back into the donor animal's inferior lacrimal gland (LG). This study shows that autoreactive lymphocytes injected subcutaneously in a site away from the LG is capable of inducing an autoimmune disease in a rabbit. Induced disease (ID) develops more slowly, taking 4weeks as compared to 2weeks in the direct injection model. Initially, both clinical symptoms and histopathology are less pronounced than in the direct injection ID model, but later the immunocytochemistry shows the same CD4+/CD8+ ratio of 4:1 for both injection methods. The finding that lymphocytes activated against lacrimal antigens can travel or home from the injection site back to the inferior and superior LG, as well as the conjunctiva, suggests that these anatomical sites may have common epitopes that induce pathogenic CD4+ T cells that produce a Sjögren's-like syndrome.

Increased degradation of extracellular matrix structures of lacrimal glands implicated in the pathogenesis of Sjögren's syndrome

Lacrimal glands (LGs) of male non-obese diabetic (NOD) mice display many features of human LGs in patients afflicted with the autoimmune disease Sjögren's syndrome (SS), including the loss of secretory functions and a lymphocytic infiltration into the glands by 4 months of age. So far, research has mainly focused on the intracellular events that are involved in initiating LG dysfunction; however, the impact of SS on extracellular matrix (ECM) structures of the diseased LGs has not yet been determined. In this study we identified and compared LG ECM formation and integrity of age-matched male healthy (BALB/c) and diseased (NOD) mice. LG tissues were examined using routine histological, biochemical, immunohistochemical and gene expression analysis. Multiphoton imaging and second-harmonic generation (SHG) microscopy permitted the non-invasive analysis of major LG ECM structures including collagen- and elastin-containing fibers. Biochemical testing demonstrated a significant loss of collagen, glycosaminoglycans and desmosine in NOD LGs when compared to healthy BALB/c LGs. Immunohistochemical staining and gene expression analysis confirmed this disease-related alteration of LG ECM structures. Furthermore, laser-induced autofluorescence and SHG microscopy revealed dramatic changes in the structural organization of most collagenous and elastic fibers of the diseased LG tissues that were more pronounced than those displayed by histological analysis. Our results clearly show an enhanced degradation of ECM proteins accompanied by the severe disorganization and deformation of ECM structures of diseased LG tissues. These new insights into the involvement of ECM degradation in SS may lead to novel therapies for patients suffering from dry eye disease.

Sjogrens syndrome as failed local immunohomeostasis: prospects for cell-based therapy

Sjogrens syndrome has been estimated to affect between 0.2% and 2% or more of the population. It is an autoimmune disease with the hallmark histopathology of focal, periductal, and perivascular CD4(+) cell infiltration of the lacrimal and salivary glands. The immunohistopathology is typically associated with severe lacrimal and salivary dysfunctions, which contribute to debilitating ocular surface and oral symptoms. The quality of life of patients with Sjogrens syndrome often is degraded further by serious, multisystemic manifestations, and they are subject to a forty-fold increased risk of developing B cell lymphomas. In normal lacrimal glands, secretory epithelial cells, autoimmune effector lymphocytes, and regulatory lymphocytes can be seen as collaborating to maintain a local immunohomeostasis. The epithelium contributes by secreting immunomodulatory paracrine factors and also by continuously exposing autoantigens, which thereby become available for uptake by professional antigen presenting cells (APCs). Local or systemic perturbations may initiate autoimmune pathophysiology by impairing the replacement of normally-turning-over regulatory cells, by altering epithelial production of immunomodulatory paracrine factors, by inducing intact epithelial cells to begin secreting previously cryptic epitopes (epitopes that previously were not available to bind to major histocompatibility complex (MHC) molecules and so could not be recognized by T cell antigen receptors), and by inducing epithelial cells to begin expressing MHC Class II molecules and presenting formerly cryptic epitopes directly to CD4(+) cells. This process has been modeled ex vivo with mixed cell reactions comprised of isolated epithelial cells and autologous lymphocytes. This development has occurred as studies of anterior chamber-associated immune deviation (ACAID) and other immunoregulatory phenomena have elucidated the origins and functions of several different kinds of regulatory lymphocytes and shown that regulatory lymphocytes can be generated ex vivo. It now is possible to envision strategies for exploiting each possible mode of epithelial autoantigen exposure to produce therapeutic regulatory cells that might be capable of re-establishing normal immunohomeostasis. Consideration of the hypothetical therapies identifies a number of basic questions that warrant investigation.

Research in Dry Eye: Report of the Research Subcommittee of the International Dry Eye WorkShop (2007)

Members of the DEWS Research Subcommittee reviewed research into the basic mechanisms underlying dry eye disease. Evidence was evaluated concerning the tear film, lacrimal gland and accessory lacrimal glands, ocular surface epithelia (including cornea and conjunctiva), meibomian glands, lacrimal duct system and the immune system. Consideration was given to both animal and human research data. Results are presented as a series of information matrices, identifying what is known and providing supporting references. An attempt is made to identify areas for further investigation.

Estrogen up-regulation of metalloproteinase-2 and -9 expression in rabbit lacrimal glands

Increased levels of the matrix metalloproteinases (MMPs)-2 and -9 have been found in tear fluids of patients with dry eye disease, suggesting that these MMPs may be implicated in the pathogenesis of this disease. One of the main causes of dry eye disease is lacrimal gland insufficiency. However, the contribution of the lacrimal gland (LG) to the expression and production of MMP-2 and MMP-9 in tears is not known. Since dry eye disease occurs more frequently in women, sex hormones, especially estrogens, have also been implicated in the pathogenesis of this disease. Estrogens have been shown to regulate the synthesis levels of MMP-2 and MMP-9 in several tissues, Thus, the purpose of these studies was to determine if: (1) rabbit lacrimal glands secrete MMP-2 and MMP-9; (2) MMP-2 and MMP-9 are produced by lacrimal epithelial cells and/or lacrimal lymphocytes; and (3) the expression, activity and level of these enzymes are regulated by sex hormones. Lacrimal epithelial cells (LEC) and lacrimal lymphocytes (LL) from sexually mature New Zealand White female rabbits were isolated, purified and cultured with and without 10(-6)M dihydrotestosterone (DHT) or 10(-6), 10(-8), 10(-9) and 10(-10)M 17beta-estradiol (E2). The culture supernatants were analyzed by zymography and western blotting (WB) using polyclonal anti-human MMP-2 and MMP-9 antibodies. LGs were also collected from rabbits 7 days after being sham-operated, ovariectomized (OVX), OVX treated with 4 mg/kg DHT, and OVX treated with 0.5 mg/kg of E2. LGs were collected and processed for RNA extraction as well as protein determination using WB and immunocytochemistry. The pro-forms of MMP-2 and MMP-9 were detected in primary LEC and LL culture medium by zymography and WB. Pro-MMP-2 and pro-MMP-9 were also detected at the gene and protein levels in the lacrimal glands of all four treatment groups, with the highest levels and gene expression found in the estrogen-treated group. These results suggest that both pro-MMP-2 and pro-MMP-9 are secreted by the lacrimal gland and appear to be up-regulated by estrogen. The role of the lacrimal MMPs in the pathogenesis of dry eye disease needs to be further investigated.

Current status of gene delivery and gene therapy in lacrimal gland using viral vectors

Gene delivery is one of the biggest challenges in the field of gene therapy. It involves the efficient transfer of transgenes into somatic cells for therapeutic purposes. A few major drawbacks in gene delivery include inefficient gene transfer and lack of sustained transgene expression. However, the classical method of using viral vectors for gene transfer has circumvented some of these issues. Several kinds of viruses, including retrovirus, adenovirus, adeno-associated virus, and herpes simplex virus, have been manipulated for use in gene transfer and gene therapy applications. The transfer of genetic material into lacrimal epithelial cells and tissues, both in vitro and in vivo, has been critical for the study of tear secretory mechanisms and autoimmunity of the lacrimal gland. These studies will help in the development of therapeutic interventions for autoimmune disorders such as Sjögren's syndrome and dry eye syndromes which are associated with lacrimal dysfunction. These studies are also critical for future endeavors which utilize the lacrimal gland as a reservoir for the production of therapeutic factors which can be released in tears, providing treatment for diseases of the cornea and posterior segment. This review will discuss the developments related to gene delivery and gene therapy in the lacrimal gland using several viral vector systems.

Effect of inflammation on lacrimal gland function

The lacrimal gland is the main contributor to the aqueous layer of the tear film. It secretes proteins, electrolytes and water, which helps to nourish and protect the ocular surface. Lacrimal gland secretion is primarily under neural control, which is achieved through a neural reflex arc. Stimuli to the ocular surface activate afferent sensory nerves in the cornea and conjunctiva. This in turn activates efferent parasympathetic and sympathetic nerves in the lacrimal gland to stimulate secretion. Sex steroid hormones are also important regulators of lacrimal gland functions. A decrease or lack of lacrimal gland secretion is the leading cause of aqueous tear deficient dry eye syndrome (DES). It has been suggested that DES is an inflammatory disorder that affects the ocular surface and the lacrimal gland. In several pathological instances, the lacrimal gland can become a target of the immune system and show signs of inflammation. This can result from autoimmune diseases (Sjögren's syndrome), organ transplantation (graft versus host disease), or simply as a result of aging. The hallmarks of lacrimal gland inflammation are the presence of focal lymphocytic infiltrates and increased production of proinflammatory cytokines. The mechanisms leading to lacrimal gland dysfunction are still poorly understood. Apoptosis, production of autoantibodies, hormonal imbalance, alterations in signaling molecules, neural dysfunction, and increased levels of proinflammatory cytokines have been proposed as possible mediators of lacrimal gland insufficiency in disease states.

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

BACKGROUND

The 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.

METHODS

The effect of adenovirus-mediated transfer of tumor necrosis factor (TNF)-alpha 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.

RESULTS

Two 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.

CONCLUSION

We 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.

Changes in the tear film and ocular surface from dry eye syndrome

Dry eye syndrome (DES) refers to a spectrum of ocular surface diseases with diverse and frequently multiple aetiologies. The common feature of the various manifestations of DES is an abnormal tear film. Tear film abnormalities associated with DES are tear deficiency, owing to insufficient supply or excessive loss, and anomalous tear composition. These categorizations are artificial, as in reality both often coexist. DES disrupts the homeostasis of the tear film with its adjacent structures, and adversely affects its ability to perform essential functions such as supporting the ocular surface epithelium and preventing microbial invasion. In addition, whatever the initial trigger, moderate and severe DES is characterized by ocular surface inflammation, which in turn becomes the cause and consequence of cell damage, creating a self-perpetuating cycle of deterioration. Progress has been made in our understanding of the aetiology and pathogenesis of DES, and these advances have encouraged a proliferation of therapeutic options. This article aims to amalgamate prevailing ideas of DES development, and to assist in that, relevant aspects of the structure, function, and production of the tear film are reviewed. Additionally, a synopsis of therapeutic strategies for DES is presented, detailing treatments currently available, and those in development.

Interactions of testosterone and all-trans retinoic acid in regulation of androgen receptor expression in rat lacrimal gland

All-trans retinoic acid down-regulates androgen receptor (AR) expression in lacrimal gland acinar cells in culture. The goal of this study was to determine if retinoic acid inhibits androgen-stimulated up-regulation of AR protein and AR mRNA expression in lacrimal glands of orchiectomized rats in vivo. Delivery of androgens to orchiectomized rats was accomplished by subcutaneous implantation of a 25 or 50 mg 21-day slow-release testosterone pellet. Rats were treated with retinoic acid by gastric gavage at 20 mg kg(-1) day(-1). After 7 days of treatment lacrimal glands were removed, AR protein expression in frozen sections was determined by immunohistochemistry and total RNA was probed for AR mRNA expression. Serum testosterone was measured by ELISA and serum retinoic acid was detected by HPLC. Orchiectomy decreases serum testosterone to 17 +/- 8 ng dl(-1), compared to 143 +/- 27 ng dl(-1) in normal rats, and reduces the number of lacrimal acinar cell nuclei expressing ARs to less than 30% of normal. Implantation of testosterone pellets restored lacrimal AR expression, but increased serum testosterone to more than 10 times the normal levels. Retinoic acid failed to inhibit AR expression in rats with high serum testosterone. Therefore a dose-response study was conducted in which testosterone was delivered by injection of a single dose of Depotestosterone at 2.5-200 mg kg(-1). Treatment of orchiectomized rats with a dose of testosterone as low as 2.5 mg kg(-1) resulted in serum testosterone levels of 62 +/- 17 ng dl(-1) and significantly increased lacrimal gland AR expression. Delivery of retinoic acid at 20 or 50 mg kg(-1) day(-1) simultaneously with a 2.5 mg kg(-1) testosterone injection prevented restoration of lacrimal gland AR expression and significantly reduced AR mRNA expression. A pharmacologic dose of retinoic acid inhibits AR expression in lacrimal gland acinar cells in vivo, as well as in vitro. This indicates that effects of retinoic acid and testosterone are antagonistic and suggests that retinoic acid may modulate effects of testosterone on the lacrimal gland.

Tumor necrosis factor inhibitor gene expression suppresses lacrimal gland immunopathology in a rabbit model of autoimmune dacryoadenitis

PURPOSE

To evaluate the effect of tumor necrosis factor (TNF) inhibitor protein on lacrimal gland immunopathology and ocular surface disease resulting from induced dacryoadenitis.

METHODS

Autoimmune dacryoadenitis was induced in rabbits by injecting the lacrimal glands with peripheral blood lymphocytes (PBLs) activated by 5 days of coculture with autologous acinar cells in a mixed cell reaction. In the treated group, an adenoviral vector carrying the TNF inhibitor gene (AdTNFRp55-Ig) was concurrently injected with AMCR-PBL. Tear production was monitored by Schirmer test, and tears were collected for detection of TNF-inhibitor protein. Frozen sections of the glands were immunostained for expression of CD4, CD8, rabbit thymic lymphocyte antigen (RTLA), and CD18. Histological sections of lacrimal glands were examined using the TUNEL technique to monitor apoptosis.

RESULTS

Soluble TNF-inhibitor protein was detected by ELISA in tears, with titers at a maximum on day 3, declining by day 7, and undetectable by day 14. Tear production declined in the induced dacryoadenitis group but did not change when glands had been treated with AdTNFRp55-Ig simultaneously with disease induction. Tear break-up time and rose bengal staining properties were not altered by treatment. Fourteen days after the glands were injected with activated PBLs, focal mononuclear cell infiltrates were observed around ducts and venules, some of which assumed the high endothelial phenotype, and between acini. Immune cells in the infiltrates stained positive for CD4, RTLA, and CD18. Glands that received AdTNFRp55-Ig concurrently with activated PBLs had decreased numbers of CD4 cells, CD18 cells, RTLA, and apoptotic cells.

CONCLUSIONS

In vivo transduction of the lacrimal gland with AdTNFRIp55-Ig resulted in transient expression in the gland and the appearance of TNF-inhibitor protein in tears. The presence of soluble TNF-inhibitor protein partially suppressed the appearance of Sjögren's syndrome-like features of reduced tear production and the immunohistopathology associated with induced autoimmune dacryoadenitis but not tear break-up time and ocular surface disease. This may reflect immunoregulation in the lacrimal gland but not in the conjunctiva.

Lacrimal histopathology and ocular surface disease in a rabbit model of autoimmune dacryoadenitis

PURPOSE

To study the effects of induced autoimmune dacryoadenitis on lacrimal gland function, histopathology, and ocular surface disease in a rabbit model.

METHODS

One lacrimal gland was surgically excised from each experimental rabbit, and epithelial cells were purified, cultured, irradiated, and then cocultured with autologous peripheral blood lymphocytes (PBLs) for 5 days. Autoimmune dacryoadenitis was induced by injecting the autologous mixed cell reactions (AMCRs) into the rabbit's remaining lacrimal gland. Normal rabbits and rabbits with both lacrimal glands injected with nonstimulated PBLs were examined as controls. Eyes were evaluated biweekly for 8 weeks by slit-lamp biomicroscopy, Schirmer testing, tear break-up time measurement, and rose bengal examination. Sections of lacrimal glands removed at 8 weeks post-operation were immunostained using antibodies against rabbit class II major histocompatibility complex molecule (MHC-II), CD4, CD8, CD18, and rabbit thymic lymphocyte antigen (RTLA). Relative numbers of positively stained cells were quantified with a ChromaVision image analysis system.

RESULTS

During an 8-week period, a continuous decrease in tear production and stability, accompanied by a continuous increase in rose bengal staining, occurred in eyes in which AMCR-PBL had been injected into the ipsilateral lacrimal glands. Similar, though generally less severe, changes occurred in eyes contralateral to the AMCR-PBL-injected eyes. No obvious changes by 8 weeks in these parameters were found in eyes in which the lacrimal glands had been injected with nonstimulated PBLs or in the lacrimal gland-excised eyes contralateral to normal eyes. Interstitial cells in normal lacrimal glands expressed CD18 and RTLA antigens, but few expressed CD4, CD8, or MHC-II. Focal mononuclear cell infiltrates were only found in lacrimal glands from animals with induced autoimmune dacryoadenitis. These cells were predominantly positive for CD4 (7.3-fold increase), RTLA (7.8-fold increase), or CD18 (42-fold increase). MHC-II expression in interstitial and ductal epithelial cells was also significantly greater in these animals than in control animals. The mononuclear cell infiltrates were frequently found enveloping venules, some of which appeared to be high endothelial cell venules. The ductal epithelium also contained CD4 and CD8 immunopositivity, within the epithelium, at the lumenal surface, or surrounding the ducts. Occasionally CD4 and CD8 immunopositive cells could be identified within the acinar lumens.

CONCLUSIONS

Injection of activated PBLs (i.e., AMCR-PBLs) in the lacrimal gland induces autoimmune dacryoadenitis with immunopathologic features similar to those of Sjögren's syndrome. The lacrimal immunopathology is accompanied by typical clinical manifestations of dry eye syndrome. The persistent significant dry eye does not appear to result just from failure of the diseased gland but from a more general dysfunction of the surface secretory tissues.

Down-regulation of androgen receptor expression and inhibition of lacrimal gland cell proliferation by retinoic acid

Androgens and retinoids are known to be involved in control of lacrimal gland function. Because retinoids generally antagonize androgen function it was the purpose of this study to investigate interactions of retinoic acid and androgens in rabbit lacrimal acinar cells in culture by determining effects of retinoic acid on androgen receptor (AR) mRNA expression, AR protein levels and androgen-stimulated cell proliferation. Experiments were conducted using primary rabbit lacrimal acinar cells and a transformed rabbit lacrimal acinar cell line. Exposure of primary lacrimal acinar cells in culture to 10(-10)-10(-6)M all-trans retinoic acid for 4-24hr causes an approximately 50% decrease in AR mRNA expression. Expression of AR protein in primary and transformed rabbit lacrimal acinar cells was confirmed by immunohistochemistry. Exposure of the primary cells to 10(-6)M retinoic acid for 24hr caused a 40% decrease in AR protein levels as determined by measurement of binding of(3) [H]-dihydrotestosterone (DHT) to cells in culture and Scatchard analysis. Exposure to 10(-9)-10(-6)M DHT stimulates proliferation of transformed rabbit lacrimal acinar cells. This effect is receptor mediated since it is blocked by the AR antagonist, flutamide. Proliferation of the lacrimal acinar cells is inhibited by retinoic acid, as compared to control, and retinoic acid also completely inhibits androgen stimulation of cell proliferation. This study supports the hypothesis that androgens play a supportive role in lacrimal gland function. The antagonistic influences of androgens and retinoic acid suggests that, under physiologic conditions there is a balance between the effects of androgens and retinoids in the lacrimal gland. A decrease in androgen levels in a dry eye patient may alter the balance between the effects of these important controllers of gene expression. The antagonistic effect of retinoids on androgens in the lacrimal gland must also be considered when devising pharmaceutical treatments for dye eye.

Diverse perturbations may alter the lacrimal acinar cell autoantigenic spectra

Lacrimal gland acinar cell autoantigens in Sjögren's syndrome include both intracellular proteins and plasma membrane proteins, to which the immune system normally must be tolerant. Attention has largely focused on the roles apoptotic cell death may play in exposing sequestered autoantigens and novel surface epitopes. We hypothesize that perturbations of ongoing membrane traffic in intact, functioning cells may also increase autoantigen exposure. We review the vesicular traffic between acinar cell basal-lateral plasma membranes (blm) and endomembrane compartments, then describe experiments in which isolated acinar cells were stimulated with epidermal growth factor (EGF), lysed, and analyzed by sorbitol gradient centrifugation. Whereas the cholinergic agonist, carbachol, impairs traffic from the trans-Golgi network to prelysosomes, causing Golgi, secretory, and lysosomal proteins to reflux into domains of the trans-Golgi network that communicate with the blm and to accumulate in the blm, EGF specifically causes a 2.6-fold (P < 0.05) increase in the beta-hexosaminidase content of the blm fraction, apparently by impairing traffic from early endosomes to prelysosome. We, therefore, suggest that a variety of physiologic stimuli may alter the spectra of autoantigens acinar cells secrete to the interstitium, express in their blm, and present via MHC Class II molecules after proteolytic processing.

Expression of IL-10 and TNF-inhibitor genes in lacrimal gland epithelial cells suppresses their ability to activate lymphocytes

PURPOSE

To determine whether the expression of either interleukin-10 (IL-10) or tumor necrosis factor (TNF) inhibitor genes in transduced rabbit lacrimal gland epithelial cells suppresses lymphocyte proliferation in an autologous mixed cell reaction, an apparent in vitro model of autoimmune dacryoadenitis.

METHODS

Purified lacrimal gland epithelial cells, transduced with an adenovirus vector carrying either viral IL-10 or TNF-inhibitor genes, were used to study their effects on the proliferation of autologous lymphocytes as monitored by 3H-thymidine incorporation in a mixed cell reaction. After transduction, both epithelial cells and lymphocytes were cultured separately for 2 days and then epithelial cells were irradiated. Equal numbers of both cell types were then cocultured together for 5 days. Cocultures were pulsed with 3H-thymidine and isotope incorporation was determined. Gene expression was detected by enzyme-linked immunosorbent assay and Western blots.

RESULTS

Lymphocyte proliferation was stimulated by epithelial cells and 3H-thymidine incorporation was significantly greater in these cocultures than in controls. The proliferation was significantly diminished in the presence of transduced cells producing either IL-10 or TNF inhibitor.

CONCLUSIONS

Transduction of lacrimal gland epithelial cells with adenovirus vectors encoding for either IL-10 or TNF-inhibitor proteins leads to expression of functional proteins capable of suppressing lymphocyte proliferation. Thus, lacrimal gland epithelial cells are a plausible target for gene therapy methods meant to produce immunoregulatory proteins.

Autologous lacrimal-lymphoid mixed-cell reactions induce dacryoadenitis in rabbits

Autoimmune dacryoadenitis, such as occurs in Sjögren's syndrome, is a frequent cause of lacrimal insufficiency, which in turn can cause dry eye. Rabbits are used frequently to test ocular therapies. Our goal is to develop a rabbit model of autoimmune dacryoadenitis to identify and test candidate therapies. Our approach arises from the observations that lacrimal gland epithelial cells stimulate proliferation in cultured autologous lymphocyte preparations and that an anti-MHC II antibody blocks this proliferation. The purpose of this study was to determine if injecting this proliferating autologous mixed cell reaction could induce dacryoadenitis in rabbits. After establishing that irradiated lacrimal gland epithelial cells stimulate proliferation in autologous peripheral blood lymphocytes, irradiated cells from a single lacrimal gland were co-cultured with autologous lymphocytes and after 5 days the mixed cell reaction, or components of the reaction, were injected into the contralateral lacrimal gland of the donor rabbit. After 2 weeks, the injected glands were removed and lymphocytic infiltration quantitated using digital image analysis of immunostained histological sections. Injecting an autologous mixed cell reaction of co-cultured irradiated lacrimal gland epithelial cells and lymphocytes reliably induced abundant periductal foci of >200 lymphocytes expressing CD18 and/or a rabbit thymic lymphocyte antigen (RTLA). Injection of medium or autologous lymphocytes alone elicited little response; injections of lymphocytes cultured with lysates of lacrimal gland epithelial cells elicited variable, modest responses. These lysates did not stimulate proliferation in the mixed cell reaction and proliferation was not observed if a porous membrane separated co-cultured lacrimal gland cells and lymphocytes. The results demonstrate that injecting an autologous mixed cell reaction of lacrimal gland epithelial cells and lymphocytes reliably creates a model of autoimmune dacryoadenitis. The relative ineffectiveness of components of the reaction to do the same supports the hypothesis that lacrimal gland epithelial cells trigger or exacerbate lacrimal autoimmune disease by presentation of autoantigens via MHC II. This experimental system can aid efforts to further understand mechanisms of diseases, and to identify and test candidate therapies.