Lacrimal Gland Cells Research Articles

Molecular Mechanisms Responsible for Mesenchymal Stem Cell-Dependent Attenuation of Tear Hyperosmolarity and Immune Cell-Driven Inflammation in the Eyes of Patients with Dry Eye Disease

Background: Dry eye disease (DED) is a chronic condition characterized by a decrease in tear production or an increase in tear evaporation, leading to inflammation and damage of the ocular surface. Dysfunction of ion channels, tear hyperosmolarity and immune cell-driven inflammation create a vicious circle responsible for the pathological changes in the eyes of DED patients. Mesenchymal stem cells (MSCs) are adult, rapidly proliferating stem cells that produce a large number of immunoregulatory, angiomodulatory, and growth factors that efficiently reduce tear hyperosmolarity-induced pathological changes, inhibit harmful immune response, and provide trophic support to the injured corneal and conjuctival epithelial cells, goblet cells and acinar cells in lacrimal glands of DED patients. Methods: An extensive research in the literature was implemented in order to elucidate the role of MSCs in the attenuation of tear hyperosmolarity and eye inflammation in patients suffering from DED. Results: Findings obtained in preclinical and pilot clinical studies demonstrated that MSCs reduced tear hyperomsolaity-induced pathological changes and suppressed immune cell-driven eye inflammation. Additionally, MSC-based therapy managed to successfully address the most severe DED-related conditions and complications. Conclusions: MSCs should be considered as potentially new therapeutic agents for the treatment of severe DED.

Unveiling senescence-associated ocular pathogenesis via lacrimal gland organoid magnetic bioassembly platform and HMGB1-Box A gene therapy

Dry eye disease (DED) is a multifactorial aging disorder leading to tear film insufficiency and instability. Yet, an important knowledge gap lingers in understanding senescence-associated ocular pathogenesis, due to limited in vitro translational lacrimal gland (LG) models. Consequently, this remains a major roadblock to discover effective therapies for the restoration of tear film secretion. Herein, the authors reported the magnetic bioassembly of two LG organoid platforms to recapitulate functional and aging states. Using a proof-of-concept approach, porcine primary LG cells were assembled into organoids via a magnetic 3D bioprinting (M3DB) platform. This platform could form reproducible LG organoids with epithelial hallmarks (AQP5+) and exhibit epithelial secretory functions (lysozyme activity). DNA damage-induced senescence and cell death was induced with etoposide, and LG organoid hypofunction and senescence-associated pathogenesis were observed. To confer DNA protection against aging, a novel gene therapy with Box A domain of high-mobility group box-1 (HMGB1-Box A) previously established by our group, was applied here to prevent LG cellular senescence for the first time. HMGB1-Box A transfection prevented LG organoids from senescence-associated pathogenesis at the transcriptomic, metabolomic and proteomic levels. Thus, M3DB platforms could generate functional and DNA damage-induced senescence LG organoids, and this latter damage could be prevented with HMGB1-Box A gene therapy.

Distinctive small molecules blend: Promotes lacrimal gland epithelial cell proliferation in vitro and accelerates lacrimal gland injury repair in vivo

PurposeThis study aims to develop a novel serum-free culture strategy containing only two small molecules, Y27632 and SB431542 (2C), for in vitro expansion of mouse lacrimal gland epithelial cells (LGECs) and investigate an innovative therapeutic approach for lacrimal gland (LG) injury. MethodsLGECs proliferative capacity was assessed by cell counting, crystal violet staining, qRT-PCR and immunofluorescence. Cell differentiation was achieved by manipulating culture conditions and assessed by qRT-PCR and AQP5 immunofluorescence. LGECs were seeded in Matrigel for three-dimensional culture and assessed by qRT-PCR and immunofluorescence. Secretory function of the cultures was assayed by ELISA. In vivo, 2C injection verified its reparative capacity in a mouse LG injury model. Corneal fluorescein staining, phenol red cotton thread, H&E, immunofluorescence and Western blot were used to assess LG injury repair. ResultsLGECs cultured with 2C exhibited high expression of stemness/proliferation markers and maintained morphology and proliferative capacity even after the tenth passage. Removal of 2C was efficacious in achieving LGECs differentiation, characterized by the increased AQP5 expression and LTF secretion. 3D spheroids cultured with 2C demonstrated differentiation potential, forming microglandular structures containing multiple LG cell types with secretory functions after 2C removal. In vivo, 2C improved the structural integrity and function of the injured LG. ConclusionsWe present a small molecule combination, 2C, that promotes LGECs expansion and differentiation in vitro and accelerates LG injury repair in vivo. This approach has potential applications for providing a stable source of seed cells for tissue engineering applications, providing new sights for LG-related diseases treatment.

The Role of Aquaporin 4 in Lacrimal Gland Ductal Fluid Secretion in Mice.

Earlier reports highlighted the predominant presence of aquaporin 4 (AQP4) in the duct cells of rabbit lacrimal glands (LGs). Whereas significant alterations in AQP4 mRNA levels have been observed in experimental dry eye and during pregnancy, the impact of AQP4 in LG ductal fluid production remains unclear. In our recent work, the role of AQP4 in LG ductal fluid secretion was investigated utilizing wild type (WT) and AQP4 knock out (KO) mice. Tear production was assessed in both WT and KO animals. Immunostaining was used to identify AQP4 protein. Duct segments were harvested from LGs of WT and KO mice. Fluid secretion and filtration permeability (Pf) were quantified using video-microscopy. Ductal tear production, elicited by a cell-permeable cAMP analogue (8-bromo cAMP), carbachol, vasoactive intestinal peptide (VIP), and phenylephrine (PHE), were assessed in both WT and KO ducts. A higher expression of AQP4 protein was noted in the duct cells from WT mice when compared to acinar cells. Pf did not show notable alterations between WT and AQP4 KO ducts. Carbachol elicited comparable secretory responses in ducts from both WT and KO animals. However, 8-bromo cAMP, VIP, and PHE stimulation resulted in decreased secretion in ducts from AQP4 KO LGs. Our findings underscore the functional relevance of AQP4 in the fluid production of mouse LG ducts. AQP4 seems to play different roles in fluid secretions elicited by different secretagogues. Specifically, cAMP-mediated, and adrenergic agonist-related secretions were reduced in AQP4 KO ducts.

Single-cell RNA-sequencing reveals the transcriptional landscape of lacrimal gland in GVHD mouse model

PurposeTo investigate the global transcriptional landscape of lacrimal gland cell populations in the GVHD mouse model. MethodsSingle-cell RNA sequencing and further bioinformatic analysis of dissociated lacrimal gland (LG) cells from the mouse model were performed. Parts of transcriptional results were confirmed by immunofluorescence staining. ResultsWe identified 23 cell populations belonging to 11 cell types. In GVHD LG, the proportion of acinar cells, myoepithelial cells, and endothelial cells was remarkably decreased, while T cells and macrophages were significantly expanded. Gene expression analysis indicated decreased secretion function, extracellular matrix (ECM) synthesis, and increased chemokines of myoepithelial cells. A newly described epithelial population named Lrg1high epithelial cells, expressing distinct gene signatures, was exclusively identified in GVHD LG. The fibroblasts exhibited an inflammation gene pattern. The gene pattern of endothelial cells suggested an increased ability to recruit immune cells and damaged cell-cell junctions. T cells were mainly comprised of Th2 cells and effective memory CD8+ T cells. GVHD macrophages exhibited a Th2 cell-linked pattern. ConclusionsThis single-cell atlas uncovered alterations of proportion and gene expression patterns of cell populations and constructed cell-cell communication networks of GVHD LG. These data may provide some new insight into understanding the development of ocular GVHD.

A New Immortalized Human Lacrimal Gland Cell Line.

The lacrimal gland is crucial for maintaining ocular health by producing the aqueous component of the tear film, which hydrates and nourishes the ocular surface. Decreased production of this component results in dry eye disease, a condition affecting over 250 million people worldwide. However, the scarcity of primary human material for studying its underlying mechanisms and the absence of a cell model for human lacrimal gland epithelial cells present significant challenges. Here, we describe the generation of immortalized human lacrimal gland cell lines through the introduction of an SV40 antigen. We successfully isolated and characterized three cell clones from a female lacrimal gland donor, confirming their epithelial identity through genomic and protein analyses, including PCR, RNAseq, immunofluorescence and cultivation in a 3D spheroid model. Our findings represent a significant advancement, providing improved accessibility to investigate the molecular pathogenesis mechanisms of dry eye disease and potential therapeutic interventions. We identified the expression of typical epithelial cell marker genes and demonstrated the cells' capability to form 2D cell sheets and 3D spheroids. This establishment of immortalized human lacrimal gland cells with epithelial characteristics holds promise for future comprehensive studies, contributing to a deeper understanding of dry eye disease and its cellular mechanisms.

Enhancement of lacrimal gland cell function by decellularized lacrimal gland derived hydrogel

Sustainable treatment of aqueous deficient dry eye (ADDE) represents an unmet medical need and therefore requires new curative and regenerative approaches based on appropriate in vitro models. Tissue specific hydrogels retain the individual biochemical composition of the extracellular matrix and thus promote the inherent cell´s physiological function. Hence, we created a decellularized lacrimal gland (LG) hydrogel (dLG-HG) meeting the requirements for a bioink as the basis of a LG model with potential for in vitro ADDE studies. Varying hydrolysis durations were compared to obtain dLG-HG with best possible physical and ultrastructural properties while preserving the original biochemical composition. A particular focus was placed on dLG-HG´s impact on viability and functionality of LG associated cell types with relevance for a future in vitro model in comparison to the unspecific single component hydrogel collagen type-I (Col) and the common cell culture substrate Matrigel. Proliferation of LG epithelial cells (EpC), LG mesenchymal stem cells, and endothelial cells cultured on dLG-HG was enhanced compared to culture on Matrigel. Most importantly with respect to a functional in vitro model, the secretion capacity of EpC cultured on dLG-HG was higher than that of EpC cultured on Col or Matrigel. In addition to these promising cell related properties, a rapid matrix metalloproteinase-dependent biodegradation was observed, which on the one hand suggests a lively cell–matrix interaction, but on the other hand limits the cultivation period. Concluding, dLG-HG possesses decisive properties for the tissue engineering of a LG in vitro model such as cytocompatibility and promotion of secretion, making it superior to unspecific cell culture substrates. However, deceleration of biodegradation should be addressed in future experiments.

Cell technologies as a basis for the development of regenerative principles for the treatment of lacrimal gland diseases

The lacrimal gland (LG) is a tubuloacinar exocrine gland composed of acinar, ductal, and myoepithelial cells. Three-dimensional distribution of acinar lobules, ducts, and myoepithelial cells is necessary for the effective functioning of the organ. LG is the main organ of immune surveillance of the ocular surface system. The embryogenesis of the gland is regulated by the interaction of genetic mechanisms, internal epigenetic (enzyme systems, hormones) and exogenous factors. There is no doubt that there is a clear genetic program for the implementation of the complex process of embryonic development. The mechanisms regulating LG organogenesis initiate the work of a huge number of structural oncogenes, transcription and growth factors, etc. Studying the expression and selective activity of regulatory genes during organ development, their participation in the differentiation of different cell types is a current trend at the nexus of clinical genetics, molecular biology, embryology and immunocytochemistry. Due to its relatively simple structure and accessibility, human LG is a suitable object for potential application in regenerative medicine. Development of a universal protocol for obtaining functional differentiated secretory epithelium of LG capable of expressing tissue-specific markers is an urgent task. Determining the nature and origin of stem cells and progenitor cells will allow the isolation and multiplication of these cells in culture. After obtaining a functionally active culture of LG cells, it is possible to create a model of autoimmune diseases.

ADSC-Exos outperform BMSC-Exos in alleviating hydrostatic pressure-induced injury to retinal ganglion cells by upregulating nerve growth factors.

Mesenchymal stem cells (MSCs) have protective effects on the cornea, lacrimal gland, retina, and photoreceptor cell damage, which may be mediated by exosomes (exos) released by MSCs. To investigate the ameliorating effect of exos derived from different MSCs on retinal ganglion cell (RGC) injury induced by hydrostatic pressure. The RGC injury model was constructed by RGC damage under different hydrostatic pressures (40, 80, 120 mmHg). Then RGCs were cultured with adipose-derived stem cell (ADSC)-Exos and bone marrow-derived stem cell (BMSC)-Exos. Cell Counting Kit-8, transmission electron microscopy, flow cytometry, immunofluorescence, real-time quantitative polymerase chain reaction, and western blotting were performed to detect the ameliorating effect of exos on pressure-induced RGC injury. ADSC-Exos and BMSC-Exos were successfully isolated and obtained. The gibbosity of RGCs was lower, the cells were irregularly ellipsoidal under pressure, and the addition of ADSC-Exos and BMSC-Exos significantly restored RGC morphology. Furthermore, the proliferative activity of RGCs was increased and the apoptosis of RGCs was inhibited. Moreover, the levels of lactate dehydrogenase and apoptosis-related proteins were increased, and the concentrations of antiapoptotic proteins and neurotrophic factors were decreased in damaged RGCs. However, the above indicators were significantly improved after ADSC-Exos and BMSC-Exos treatment. These findings indicated that ADSC-Exos and BMSC-Exos could ameliorate RGC injury caused by hydrostatic pressure by inhibiting apoptosis and increasing the secretion of neurotrophic factors.

The immunoglobulin A isotype of the Arabian camel (Camelus dromedarius) preserves the dualistic structure of unconventional single-domain and canonical heavy chains.

The evolution of adaptive immunity in Camelidae resulted in the concurrent expression of classic heterotetrameric and unconventional homodimeric heavy chain-only IgG antibodies. Heavy chain-only IgG bears a single variable domain and lacks the constant heavy (CH) γ1 domain required for pairing with the light chain. It has not been reported whether this distinctive feature of IgG is also observed in the IgA isotype. Gene-specific primers were used to generate an IgA heavy chain cDNA library derived from RNA extracted from the dromedary's third eyelid where isolated lymphoid follicles and plasma cells abound at inductive and effector sites, respectively. Majority of the cDNA clones revealed hallmarks of heavy chain-only antibodies, i.e. camelid-specific amino acid substitutions in framework region 1 and 2, broad length distribution of complementarity determining region 3, and the absence of the CHα1 domain. In a few clones, however, the cDNA of the canonical IgA heavy chain was amplified which included the CHα1 domain, analogous to CHγ1 domain in IgG1 subclass. Moreover, we noticed a short, proline-rich hinge, and, at the N-terminal end of the CHα3 domain, a unique, camelid-specific pentapeptide of undetermined function, designated as the inter-α region. Immunoblots using rabbit anti-camel IgA antibodies raised against CHα2 and CHα3 domains as well as the inter-α region revealed the expression of a ~52 kDa and a ~60 kDa IgA species, corresponding to unconventional and canonical IgA heavy chain, respectively, in the third eyelid, trachea, small and large intestine. In contrast, the leporine anti-CHα1 antibody detected canonical, but not unconventional IgA heavy chain, in all the examined tissues, milk, and serum, in addition to another hitherto unexplored species of ~45 kDa in milk and serum. Immunohistology using anti-CHα domain antibodies confirmed the expression of both variants of IgA heavy chains in plasma cells in the third eyelid's lacrimal gland, conjunctiva, tracheal and intestinal mucosa. We found that in the dromedary, the IgA isotype has expanded the immunoglobulin repertoire by co-expressing unconventional and canonical IgA heavy chains, comparable to the IgG class, thus underscoring the crucial role of heavy chain-only antibodies not only in circulation but also at the mucosal frontiers.

Loss of Cdc42 in Exocrine Acini Decreases Saliva Secretion but Increases Tear Secretion-A Potential Model of Exocrine Gland Senescence.

Cdc42 is a small GTPase essential for the cell cycle, morphogenesis, and cell adhesion, and it is involved in the polarity of epithelial cells. However, the functional roles of Cdc42 in exocrine glands, such as the maintenance of acini and water secretion, are not yet well understood. In this study, we generated acinar-cell-specific Cdc42 conditional knockout (Cdc42cKO) mice to assess their maintenance of acinar cells and physiological functions in the salivary glands (SGs) and lacrimal glands (LGs). Our data revealed that the loss of Cdc42 altered the luminal structures to bulging structures and induced acinar cell apoptosis in both the parotid glands (PGs) and LGs of Cdc42cKO mice. Interestingly, saliva secretion in response to pilocarpine stimulation was decreased in the Cdc42cKO group, whereas tear secretion was increased. Consistent with the water secretion results, protein expression of the water channel AQP5 in acinar cells was also decreased in the PGs but conversely increased in the LGs. Moreover, the changes that increased AQP5 expression in LGs occurred in the acinar cells rather than the duct cells. The present study demonstrates that Cdc42 is involved in the structural and survival maintenance of acinar cells in SGs and LGs. On the other hand, depletion of Cdc42 caused the opposite physiological phenomena between PGs and LGs.

Normal and Sjogren’s syndrome models of the murine lacrimal gland studied at single-cell resolution

The lacrimal gland is of central interest in ophthalmology both as the source of the aqueous component of tear fluid and as the site of autoimmune pathology in the context of Sjogren's syndrome (SjS). To provide a foundational description of mouse lacrimal gland cell types and their patterns of gene expression, we have analyzed single-cell transcriptomes from wild-type (Balb/c) mice and from two genetically based SjS models, MRL/lpr and NOD (nonobese diabetic).H2b, and defined the localization of multiple cell-type-specific protein and mRNA markers. This analysis has uncovered a previously undescribed cell type, Car6+ cells, which are located at the junction of the acini and the connecting ducts. More than a dozen secreted polypeptides that are likely to be components of tear fluid are expressed by acinar cells and show pronounced sex differences in expression. Additional examples of gene expression heterogeneity within a single cell type were identified, including a gradient of Claudin4 along the length of the ductal system and cell-to-cell heterogeneity in transcription factor expression within acinar and myoepithelial cells. The patterns of expression of channels, transporters, and pumps in acinar, Car6+, and ductal cells make strong predictions regarding the mechanisms of water and electrolyte secretion. In MRL/lpr and NOD.H2b lacrimal glands, distinctive changes in parenchymal gene expression and in immune cell subsets reveal widespread interferon responses, a T cell-dominated infiltrate in the MRL/lpr model, and a mixed B cell and T cell infiltrate in the NOD.H2b model.

Mapping Resident Immune Cells in the Murine Ocular Surface and Lacrimal Gland by Flow Cytometry

ABSTRACT Background The ocular surface and lacrimal gland have a frontline position in mucosal immunology. However, there have been few updates to the immune cell atlas of these tissues in recent years. Purpose To map the immune cells in murine ocular surface tissues and lacrimal gland. Methods Central and peripheral corneas, conjunctiva, and lacrimal gland were dissociated into single cell suspensions, followed by flow cytometry. Discrepancy of immune cells between the central and peripheral corneas was compared. In the conjunctiva and lacrimal gland, myeloid cells were clustered by tSNE and FlowSOM based on the expression of F4/80, Ly6C, Ly6G, and MHC II. ILCs, type 1 immune cells, and type 3 immune cells were analyzed. Results The number of immune cells in peripheral corneas was about 16 folds of that in central corneas. B cells accounted for 8.74% of immune cells in murine peripheral corneas. In the conjunctiva and lacrimal gland, most myeloid cells tended out to be monocytes, macrophages, and classical dendritic cells (cDCs). ILC3 were 6.28% and 3.63% of ILCs in the conjunctiva and lacrimal gland, respectively. Th1, Tc1, and NK cells were predominant type 1 immune cells. γδ T17 cells and ILC3 outnumbered Th17 cells among type 3 T cells. Conclusion B cells resident in murine corneas were reported for the first time. Additionally, we proposed a strategy of clustering myeloid cells to better understand their heterogeneity in the conjunctiva and lacrimal gland based on tSNE and FlowSOM. Furthermore, we identified the ILC3 in the conjunctiva and lacrimal gland for the first time. Compositions of type 1 and type 3 immune cells were summarized. Our study provides a fundamental reference and novel insights for ocular surface immune homeostasis and diseases.

Involvement of aberrant acinar cell proliferation in scopolamine-induced dry eye mice

Dry eye is a multifactorial disease that causes dryness, inflammation and damage of ocular surface. Subcutaneous injection of the muscarinic cholinergic antagonist scopolamine under desiccating stress reduces tear production and induces dry eye symptoms in mice. However, the expression profile and pathogenic changes of the lacrimal gland remain incompletely understood. In the present study, we performed comparative transcriptomic analysis of lacrimal glands from the control and scopolamine-treated mice. Primary analysis identified 677 upregulated genes and 269 downregulated genes in the lacrimal gland of mice with scopolamine treatment. Unexpectedly, KEGG pathway and hierarchical clustering analysis showed the enrichment of “DNA replication” and “cell cycle” categories in the upregulated genes. Subsequently, we confirmed that the acinar cells were the major proliferating cells of lacrimal gland, which exhibited significant increasing of the proliferating cell nuclear antigen (PCNA) expression after scopolamine treatment, accompanied with the upregulation of DNA damage marker γ-H2AX. More importantly, both prophylactic and therapeutic administration of the cyclin-dependent kinase (CDK) inhibitor AT7519 rescued the tear reduction and alleviated dry eye severity in the scopolamine-treated mice, including corneal epithelial barrier function, lacrimal and corneal inflammation, and conjunctival goblet cell density. Therefore, we conclude that aberrant acinar cell proliferation is involved in the scopolamine-induced tear reduction and dry eye onset, which can be improved by AT7519 treatment.

Features of water-electrolyte component of the tear fluid

Tear production is a complex multi-step process that can be arbitrarily divided into three stages: «primary» secretion by the acinar cells of the main lacrimal glands, formation of «secondary» lacrimal fluid in the ducts of the main lacrimal glands, and «tertiary» modification of the tear composition in the conjunctival sac. This article highlights mechanisms of water and electrolytes secretion in the process of tear fluid production and describes the particularities of distribution of the membrane transport proteins in the lacrimal gland and the ocular surface.

Effect of Aucubin-Containing Eye Drops on Tear Hyposecretion and Lacrimal Gland Damage Induced by Urban Particulate Matter in Rats.

Exposure to particulate matter is a causative factor of dry eye disease. We aimed to investigate the beneficial effect of eye drops containing aucubin on dry eye disease induced by urban particulate matter (UPM). Dry eye was induced in male SD rats (6 weeks old) by topical exposure to UPM thrice a day for 5 d. Eye drops containing 0.1% aucubin or 0.5% aucubin were topically administered directly into the eye after UPM exposure for an additional 5 d. Tear secretion was evaluated using a phenol red thread tear test and corneal irregularity. The oxidative damage in the lacrimal gland was evaluated using TUNEL and immunohistochemical staining. The topical administration of aucubin significantly attenuated UPM-induced tear hyposecretion (control group: 9.25 ± 0.62 mm, UPM group: 4.55 ± 0.25 mm, 0.1% aucubin: 7.12 ± 0.58 mm, and 0.5% aucubin: 7.88 ± 0.75 mm) and corneal irregularity (control group: 0.00 ± 0.00, UPM group: 3.40 ± 0.29, 0.1% aucubin: 1.80 ± 0.27, and 0.5% aucubin: 1.15 ± 0.27). In addition, aucubin also reduced the UPM-induced apoptotic injury of lacrimal gland cells induced by oxidative stress through the increased expression of HMGB1 and RAGE. These findings indicate that the topical administration of aucubin eye drops showed a beneficial effect against UPM-induced abnormal ocular changes, such as tear hyposecretion and lacrimal gland damage. Therefore, our results reveal the pharmacological activities of aucubin in dry eye disease.

Review on the possible pathophysiological mechanisms underlying visual display terminal-associated dry eye disease.

Visual display terminal (VDT) use is a key risk factor for dry eye disease (DED). Visual display terminal (VDT) use reduces the blink rate and increases the number of incomplete blinks. However, the exact mechanisms causing DED development from VDT use have yet to be clearly described. The purpose of the study was to conduct a review on pathophysiological mechanisms promoting VDT-associated DED. A PubMed search of the literature investigating the relationship between dry eye and VDT was performed, and relevance to pathophysiology of DED was evaluated. Fifty-five articles met the inclusion criteria. Several pathophysiological mechanisms were examined, and multiple hypotheses were extracted from the articles. Visual display terminal (VDT) use causes DED mainly through impaired blinking patterns. Changes in parasympathetic signalling and increased exposure to blue light, which could disrupt ocular homeostasis, were proposed in some studies but lack sufficient scientific support. Together, these changes may lead to a reduced function of the tear film, lacrimal gland, goblet cells and meibomian glands, all contributing to DED development. Visual display terminal (VDT) use appears to induce DED through both direct and indirect routes. Decreased blink rates and increased incomplete blinks increase the exposed ocular evaporative area and inhibit lipid distribution from meibomian glands. Although not adequately investigated, changes in parasympathetic signalling may impair lacrimal gland and goblet cell function, promoting tear film instability. More studies are needed to better target and improve the treatment and prevention of VDT-associated DED.

Activation of Mast-Cell-Derived Chymase in the Lacrimal Glands of Patients with IgG4-Related Ophthalmic Disease.

The purpose of this present study was to investigate the distribution and expression of chymase in the lacrimal glands (LGs) of patients afflicted with IgG4-related ophthalmic disease (IgG4-ROD). LGs from patients with severe canalicular obstruction were considered the control group. Toluidine blue staining confirmed a significant increase in the number of mast cells in the LGs obtained from the IgG4-ROD patients. In addition, immunostaining of serial sections from the LGs showed a significant increase in the number of chymase-positive cells and tryptase-positive cells in the IgG4-ROD LGs compared to the normal control LGs. The mRNA expression of chymase, tryptase, TGF-β1, and collagen-I tended to increase in the IgG4-ROD LGs. Immunostaining of vimentin and α-smooth muscle actin (α-SMA) showed that myofibroblasts were the main cellular components in severely fibrotic regions of LGs in patients with IgG4-ROD. Linear regression analyses on the number of mast cells, chymase-positive cells, and tryptase-positive cells revealed significant positive correlations between those respective cells. Our findings suggest that chymase may play a role in the fibrotic disorder of IgG4-ROD LGs through the regulation of TGF-β1 activation and collagen-I deposition, and that it may be a therapeutic target for patients afflicted with IgG4-ROD.

Concurrent lacrimal gland melanocytoma and ocular melanocytosis in a dog.

A 9-y-5-mo-old, spayed female, mixed-breed dog with buphthalmia and elevated intraocular pressure in the left eye, consistent with glaucoma, was evaluated. Black-pigmented, slightly elevated tissue with irregular margins was noted on the dorsolateral aspect of the left globe. Ultrasonography detected a mass, later identified as lacrimal gland, adjacent to the globe and the thickened uvea. The surgically removed lacrimal gland was effaced by dense sheets of melanin-laden cells. Within the enucleated globe, numerous melanin-laden cells infiltrated and expanded the rostral two-thirds thickness of the cornea, the entire anterior uvea (iris and ciliary body), and a rostral portion of the choroid. Melanin-laden cells in the left lacrimal gland and globe showed no nuclear atypia or mitotic figures, and reacted to anti-S100 and anti-melan A antibodies by immunohistochemistry. Our final diagnosis was concurrent lacrimal gland melanocytoma and ocular melanocytosis. The trabecular meshwork of the eye was obliterated by melanin-laden cells, which was the likely cause of glaucoma in this patient. To our knowledge, melanocytoma affecting the lacrimal gland has not been reported previously in a non-human mammalian species. Veterinary clinicians are encouraged to include melanocytoma in the differential list when examining an enlarged lacrimal gland.

Aquaporins 8 and 9 as Possible Markers for Adult Murine Lacrimal Gland Cells.

Aquaporins (AQPs) are proteins that selectively transport water across the cell membrane. Although AQPs play important roles in secretion in the lacrimal gland, the expression and localization of AQPs have not been clarified yet. In the current study, we investigated the expression pattern of AQP family members in the murine lacrimal gland during development. Lacrimal gland tissues were harvested from E13.5 and E17.5 murine embryos and from mice 8 weeks of age (adults). Corneal and conjunctival tissues from the latter served as controls. Total RNA was isolated and analyzed for the expression of AQP family members using qPCR. The localization of AQPs in the adult lacrimal gland in adult murine lacrimal glands was also analyzed. Expression of Aqp8 and Aqp9 mRNAs was detected in the adult lacrimal gland but not in the cornea, conjunctiva, or fetal lacrimal gland. AQP8 and AQP9 and α-SMA partially colocalized around the basal regions of the acinar unit. The levels of Aqp3 mRNAs and protein were much lower in the adult lacrimal gland but were readily detected in the adult cornea and conjunctiva. Our study suggests that AQP8 and AQP9 may serve as markers for adult murine lacrimal gland, ductal, and myoepithelial cells.