The Sjögren's Working Group: The 2023 OMERACT meeting and provisional domain generation.

Sjögren's disease (SjD) is a systemic autoimmune exocrinopathy with key features of dryness, pain, and fatigue. SjD can affect any organ system with a variety of presentations across individuals. This heterogeneity is one of the major barriers for developing effective disease modifying treatments. Defining core disease domains comprising both specific clinical features and incorporating the patient experience is a critical first step to define this complex disease. The OMERACT SjD Working Group held its first international collaborative hybrid meeting in 2023, applying the OMERACT 2.2 filter toward identification of core domains. We accomplished our first goal, a scoping literature review that was presented at the Special Interest Group held in May 2023. Building on the domains identified in the scoping review, we uniquely deployed multidisciplinary experts as part of our collaborative team to generate a provisional domain list that captures SjD heterogeneity.

CD47 Binding on Vascular Endothelial Cells Inhibits IL-17-Mediated Leukocyte Adhesion.

To address the conflicting role of thrombospondin (TSP)-1 reported in acute and chronic pathologies, this study investigated the role of TSP-1 in regulating leukocyte recruitment and regulation of VCAM-1 expression using mouse models of uveitis. The spontaneously increased VCAM-1 expression and leukocyte adhesion in retinas of TSP-1-deficient mice suggested a TSP-1-mediated regulation of VCAM-1 expression. In a chronic uveitis model, induced by immunizing wild-type mice with specific interphotoreceptor retinoid-binding protein (IRBP) peptide, topically applied TSP-1-derived CD47-binding peptide significantly reduced the clinical disease course and retinal leukocyte adhesion as compared to the control peptide-treated group. In contrast, in LPS-mediated acute uveitis, TSP-1 deficiency significantly reduced the retinal leukocyte adhesion. The results of our in vitro study, using vascular endothelial cell (EC) cultures, demonstrate that unlike TNF-α, VCAM-1 expression induced by IL-17 is associated with a reduced expression of endogenous TSP-1. Such reduced endogenous TSP-1 expression in IL-17-stimulated ECs helps limit the CD36-mediated increased VCAM-1 expression, while favoring CD47-mediated inhibition of VCAM-1 expression and leukocyte adhesion. Thus, our study identifies TSP-1:CD47 interaction as a molecular pathway that modulates IL-17-mediated VCAM-1 expression, contributing to its anti-inflammatory effect in chronic inflammatory conditions.

Reduced tear thrombospondin-1/matrix metalloproteinase-9 ratio can aid in detecting Sjögren's syndrome etiology in patients with dry eye.

Differentiating patients with Sjögren's syndrome (SS)-associated dry eye from non-SS dry eye is critical for monitoring and appropriate management of possible sight- or life-threatening extraglandular complications associated with SS. We tested whether reduced tear levels of immunoregulatory thrombospondin (TSP)-1, which also inhibits matrix metalloproteinase (MMP)-9, would reflect SS pathogenesis aiding the identification of patients with SS-dry eye. Total of 61 participants, including healthy controls (n = 20), patients with non-SS dry eye (n = 20) and SS-dry eye (n = 21) were enrolled prospectively. Tear TSP-1 and MMP-9 levels were measured using a custom magnetic bead-based multi-plex assay in a masked manner. Analyte concentrations were assessed further according to ocular surface and tear film parameters. Relative to median tear TSP-1 (308 ng/ml) and MMP-9 (1.9 ng/ml) levels in the control group, significantly higher proportion of patients with SS-dry eye than non-SS had lower tear TSP-1 levels (55% vs. 29%, odds ratio [OR] = 3, 95% confidence interval [CI] = 1.64 to 5.35, p < 0.05) and higher tear MMP-9 levels (65% vs. 24%, OR = 5.8, 95% CI = 4.46 to 19.81, p < 0.05), respectively. The tear TSP-1/MMP-9 ratio was significantly reduced in patients with SS-dry eye compared to non-SS (B = -2.36, 95% CI = -3.94 to -0.0.79, p < 0.05), regardless of tear MMP-9 levels. Patients with a lower ratio were 2.3 times more likely to have SS (OR = 0.28, 95% CI = 0.1 to 0.75, p < 0.05). This ratio showed significant inverse correlations with clinical parameters (conjunctival and corneal staining scores). Our results denote that tear TSP-1/MMP-9 ratio can be useful in identifying patients with dry eye with underlying SS and used as a screening test.

Conjunctival Goblet Cell Responses to TLR5 Engagement Promote Activation of Local Antigen-Presenting Cells.

Conjunctival epithelium forms a barrier between the ocular surface microbial flora and the ocular mucosa. In addition to secreting gel-forming mucins, goblet cells, located in the conjunctival epithelium, help maintain local immune homeostasis by secreting active TGFß2 and promoting tolerogenic phenotype of dendritic cells in the vicinity. Although dendritic cell subsets, characteristic of mucosal tissues, are found in the conjunctiva, previous studies provided limited information about their location within the tissue. In this study, we examine immunostained conjunctiva explants to determine the location of CD11c-positive dendritic cells in the context of MUC5AC-positive goblet cells. Considering that conjunctival goblet cells are responsive to signaling induced by pathogen recognition receptors, we also assess if their responses to microbial product, flagellin, can contribute to the disruption of ocular mucosal homeostasis that promotes activation of dendritic cells and results in chronic ocular surface inflammation. We find that dendritic cells in the conjunctiva with an increased microbial colonization are located adjacent to goblet cells. While their cell bodies in the stromal layer are immediately below the epithelial layer, several extensions of dendritic cells are projected across the epithelium towards the ocular surface. Such trans-epithelial dendrites are not detectable in healthy ocular mucosa. In response to topically applied flagellin, increased proportion of CD11c-positive cells in the conjunctiva strongly express MHC class II relative to the untreated conjunctiva. This change is accompanied by reduced immunoreactivity to TGFß-activating Thrombospondin-1 in the conjunctival epithelium. These findings are supported by in vitro observations in primary cultures of goblet cells that respond to the TLR5 stimulation with an increased expression of IL-6 and reduced level of active TGFß. The observed changes in the conjunctiva after flagellin application correspond with the development of clinical signs of chronic ocular mucosal inflammation including corneal epitheliopathy. Collectively, these findings demonstrate the ability of ocular mucosal dendritic cells to extend trans-epithelial dendrites in response to increased microbial colonization at the ocular surface. Moreover, this study provides key insight into how goblet cell responses to microbial stimuli may contribute to the disruption of ocular mucosal homeostasis and chronic ocular mucosal inflammation.

Thrombospondin 1 polymorphism associated with decreased expression and increased risk of pterygium.

PURPOSE: To assess the potential association of a thrombospondin 1 gene (THBS1) single-nucleotide polymorphism (rs1478604) with thrombospondin 1 (TSP-1) mRNA expression, as well as the risk of pterygium, in a pilot study. METHODS: DNA and RNA were isolated from peripheral blood samples collected from normal volunteer subjects (n = 39). In addition, DNA was isolated from conjunctival tissue samples collected during pterygium excision surgeries (n = 42). Relative expression of TSP-1 mRNA was measured by quantitative RT-PCR, and rs1478604 genotype was determined using a TaqMan SNP genotyping assay. Genotype frequencies were compared with mRNA expression and between pterygium samples and normal controls. RESULTS: Expression of TSP-1 mRNA was significantly lower in the peripheral blood of normal subjects who were homozygous for the C allele of rs1478604 (CC) compared to TT and CT genotypes (p = 0.004). When we compared rs1478604 genotypes between normal and pterygium patients, we found that the CC genotype was also associated with an increased risk of pterygium compared to TT (odds ratio (OR) = 5.39, 95% CI [1.26-22.99], p = 0.028), CT (OR = 7.86, 95% CI [1.92-32.17], p = 0.003), and combined CT and TT genotypes (OR = 6.67; 95% CI = [1.75-25.37]; p = 0.003). CONCLUSIONS: We found that the C allele of rs1478604 was associated with both lower TSP-1 expression and higher risk of pterygium, possibly implicating TSP-1 in the pathogenesis of pterygium.

Immunology and Pathology in Ocular Drug Development.

Clear vision is dependent on features that protect the anatomical integrity of the eye (cornea and sclera) and those that contribute to internal ocular homeostasis by conferring hemangiogenic (avascular tissues and antiangiogenic factors), lymphangiogenic (lack of draining lymphatics), and immunologic (tight junctions that form blood-ocular barriers, immunosuppressive cells, and modulators) privileges. The later examples are necessary components that enable the eye to maintain an immunosuppressive environment that responds to foreign invaders in a deviated manner, minimizing destructive inflammation that would impair vision. These conditions allowed for the observations made by Medawar, in 1948, of delayed rejection of allogenic tissue grafts in the anterior chamber of mouse eye and permit the sequestration of foreign invaders (eg, Toxoplasma gondii) within the retina of healthy individuals. Yet successful development of intraocular drugs (biologics and delivery devices) has been stymied by adverse ocular pathology, much of which is driven by immune pathways. The eye can be intolerant of foreign protein irrespective of delivery route, and endogenous ocular cells have remarkable plasticity when recruited to preserve visual function. This article provides a review of current understanding of ocular immunology and the potential role of immune mechanisms in pathology observed with intraocular drug delivery.

Mouse Models of Sjögren's Syndrome with Ocular Surface Disease.

Sjögren's syndrome (SS) is a systemic rheumatic disease that predominantly affects salivary and lacrimal glands resulting in oral and ocular dryness, respectively, referred to as sicca symptoms. The clinical presentation of ocular dryness includes keratoconjunctivitis sicca (KCS), resulting from the inflammatory damage to the ocular surface tissues of cornea and conjunctiva. The diagnostic evaluation of KCS is a critical component of the classification criteria used by clinicians worldwide to confirm SS diagnosis. Therapeutic management of SS requires both topical and systemic treatments. Several mouse models of SS have contributed to our current understanding of immunopathologic mechanisms underlying the disease. This information also helps develop novel therapeutic interventions. Although these models address glandular aspects of SS pathology, their impact on ocular surface tissues is addressed only in a few models such as thrombospondin (TSP)-1 deficient, C57BL/6.NOD.Aec1Aec2, NOD.H2b, NOD.Aire KO, and IL-2Rα (CD25) KO mice. While corneal and/or conjunctival damage is reported in most of these models, the characteristic SS specific autoantibodies are only reported in the TSP-1 deficient mouse model, which is also validated as a preclinical model. This review summarizes valuable insights provided by investigations on the ocular spectrum of the SS pathology in these models.

Differential Diagnosis of Sjögren Versus Non-Sjögren Dry Eye Through Tear Film Biomarkers.

PURPOSE: Systemic implications necessitate the identification of dry eye patients with Sjögren syndrome (SS). This study aims to explore the utility of tear MUC5AC and inflammatory cytokine levels in the differential diagnosis of SS-related dry eye. METHODS: A prospective, observational, case-control study was conducted on 62 patients (those with a definitive diagnosis of SS dry eye, non-SS dry eye, and age-matched healthy controls with no dry eye). Clinical evaluations included the following tests in the order listed here: noninvasive tear break-up time, osmolarity, tear sampling, Schirmer test without anesthesia, and ocular surface staining (lissamine green for conjunctiva and fluorescein for cornea). Tear MUC5AC levels were assessed with enzyme-linked immunosorbent assay, and cytokines [interferon-gamma, tumor necrosis factor alpha, interleukin (IL)-6, IL-17a, IL-1ß, IL-8, IL-10, and IL-12p70] were measured using a Luminex assay in a masked fashion. RESULTS: The Bulbar conjunctival lissamine green staining score was significantly greater in patients or controls with SS versus non-SS dry eye. This greater conjunctival staining was associated with a reduction in tear MUC5AC (B = -17.8 ng/mL, 95% confidence interval = -31.8 to -3.9, P = 0.01). Among the tear cytokines, a significant association was found between IL-8 levels (hazard ratio [HR] = 1.002, 95% confidence interval = 1.000-1.003, P = 0.03) and SS diagnosis. When patients were stratified based on tear MUC5AC levels, significantly increased tear IL-8 levels were detected in patients with SS dry eye but not with non-SS dry eye, in comparison with healthy controls. CONCLUSIONS: Tear levels of goblet cell-specific MUC5AC combined with IL-8 can potentially serve as a useful biomarker for differential diagnosis of SS dry eye from non-SS dry eye.

Thrombospondin-1 in ocular surface health and disease.

Thrombospondin 1 (TSP-1) is an extracellular matrix protein that interacts with a wide array of ligands including cell receptors, growth factors, cytokines and proteases to regulate various physiological and pathological processes. Constitutively expressed by certain ocular surface tissues (e.g. corneal and conjunctival epithelium), TSP-1 expression is modulated during ocular surface inflammation. TSP-1 is an important activator of latent TGF-ß, serving to promote the immunomodulatory and wound healing functions of TGF-ß. Mounting research has deepened our understanding of how TSP-1 expression (and lack thereof) contributes to ocular surface homeostasis and disease. Here, we review current knowledge of the function of TSP-1 in dry eye disease, ocular allergy, angiogenesis/lymphangiogenesis, corneal transplantation, corneal wound healing and infectious keratitis.

Topical Application of TGF-ß-Activating Peptide, KRFK, Prevents Inflammatory Manifestations in the TSP-1-Deficient Mouse Model of Chronic Ocular Inflammation.

Chronic inflammation of the ocular surface poses a risk of vision impairment. The understanding of the molecular mechanisms that are involved in the inflammatory response is critical to identify novel molecular targets. Recently, thrombospondin-1 (TSP-1) has emerged as a key player in ocular surface homeostasis that efficiently activates the TGF-ß2 isoform that is predominantly expressed in the ocular mucosa. Here, the potential of the peptide derived from TSP-1 (KRFK), that can activate TGF-ß, is proposed as a potentially applicable therapeutic for chronic ocular surface inflammatory disorders. Our in vitro results confirm that the chosen peptide activates TGF-ß, reducing the expression of co-stimulatory molecules on dendritic cells, driving them towards a tolerogenic phenotype. For the in vivo studies, the TSP-1-/- mouse is used as a pre-clinical model of chronic ocular inflammation. We observe that the topical application of KRFK alters the peripheral balance of effectors by reducing the proportion of pathogenic Th1 and Th17 cells while increasing Treg cell proportion in cervical lymph nodes. In line with these findings, the development of chronic ocular surface inflammation is significantly prevented in KRFK-treated TSP-1-/- mice, as assessed by clinical parameters and inflammatory cytokine expression in conjunctival and lacrimal gland tissues. Together, our results identify the KRFK peptide as a novel therapeutic option to prevent the development of chronic inflammatory manifestations of the ocular surface.

Thrombospondin-1 Is Necessary for the Development and Repair of Corneal Nerves.

Thrombospondin-1-deficient (TSP-1-/-) mice are used as an animal model of Sjögren's Syndrome because they exhibit many of the symptoms associated with the autoimmune type of dry eye found in primary Sjögren's Syndrome. This type of dry eye is linked to the inflammation of the lacrimal gland, conjunctiva, and cornea, and is thought to involve dysfunction of the complex neuronal reflex arc that mediates tear production in response to noxious stimuli on the ocular surface. This study characterizes the structural and functional changes to the corneal nerves that are the afferent arm of this arc in young and older TSP-1-/- and wild type (WT) mice. The structure and subtype of nerves were characterized by immunohistochemistry, in vivo confocal microscopy, and confocal microscopy. Cytokine expression analysis was determined by Q-PCR and the number of monocytes was measured by immunohistochemistry. We found that only the pro-inflammatory cytokine MIP-2 increased in young corneas of TSP-1-/- compared to WT mice, but tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-2 (MIP-2) all increased in older TSP-1-/- mouse corneas. In contrast, CD11b+ pro-inflammatory monocytes did not increase even in older mouse corneas. Calcitonin gene-related peptide (CGRP)-, but not Substance P (SubP)-containing corneal nerves decreased in older, but not younger TSP-1-/- compared to WT mouse corneas. We conclude that CGRP-containing corneal sensory nerves exhibit distinct structural deficiencies as disease progresses in TSP-1-/- mice, suggesting that: (1) TSP-1 is needed for the development or repair of these nerves and (2) impaired afferent corneal nerve structure and hence function may contribute to ocular surface dysfunction that develops as TSP-1-/- mice age.

Dysregulated Marginal Zone B Cell Compartment in a Mouse Model of Sjögren's Syndrome with Ocular Inflammation.

The risk of developing lymphoma in patients with Sjögren's syndrome (SS) is 44 times higher than in the normal population with the most common lymphomas derived from marginal zone B (MZB) cells. Current understanding of the role of MZB cells in SS is primarily based on salivary gland pathology, while their contextual association with lacrimal glands and ocular manifestations largely remains unknown. We examined this possibility using a SS mouse model (thrombospondin-1 deficient (TSP1-/-)) with well-characterized ocular disease. We determined the frequency, localization, and cytokine profiles of MZB cells and their association with an antibody response in TSP1-/- mice treated with a TSP-derived peptide. A significantly increased frequency of MZB cells was detected in the spleens and lacrimal glands of TSP1-/- mice in comparison to wild-type tissues as detected by immunostaining. An altered cytokine profile of TSP1-/- MZB cells was supportive of T helper 17 (Th17)-related pathogenesis. A significantly reduced antibody response and the splenic MZB compartment against an eye-derived antigen were noted in TSP-derived peptide-treated mice. These changes correspond with the previously reported ability of the peptide to ameliorate SS-related ocular manifestations. Collectively, our results demonstrate dysregulation of MZB cells in TSP1-/- mice and highlight their role in the context of SS-related chronic ocular surface disease.

Alteration in nerves and neurotransmitter stimulation of lacrimal gland secretion in the TSP-1-/- mouse model of aqueous deficiency dry eye.

The purpose of this study is to determine neural, vascular, protein secretion, and cellular signaling changes with disease progression in lacrimal glands of the thrombospondin-1-/- (TSP-1-/-) mouse model of dry eye compared to C57BL/6 wild-type (WT) mice. Neural innervation was reduced in TSP-1-/- lacrimal glands compared to WT controls, whereas the number of blood vessels was increased. Intracellular Ca2+ stores and the amount of lysosomes, mitochondria, and secretory granules, but not the endoplasmic reticulum, were reduced in TSP-1-/- compared to WT acini at 12 weeks of age. Ex vivo high KCl-evoked secretion was decreased in TSP-1-/- compared to WT lacrimal gland tissue pieces. The α1D-adrenergic agonist-stimulated response was increased in TSP-1-/- at 4 and 24 weeks but decreased at 12 weeks, and the ATP and MeSATP-stimulated peak [Ca2+]i responses were decreased at 24 weeks. These changes were observed prior to the appearance of mononuclear infiltrates. We conclude that in the lacrimal gland the absence of TSP-1: injures peripheral nerves; blocks efferent nerve activation; decreases protein secretion; and alters intracellular Ca2+ stores. Through these effects the absence of TSP-1 leads to disruption of ocular surface homeostasis and development of dry eye.

Advancements in Understanding Immunogenicity of Biotherapeutics in the Intraocular Space.

Therapeutic breakthroughs in a number of retinal degenerative diseases have come about through the development of biotherapeutics administered directly into the eye. As a consequence of their use, we have gained more insight into the immune privileged status of the eye and the various considerations that development, manufacturing, and use of these drugs require. It has been observed that therapeutic proteins injected into the vitreous can elicit an immune response resulting in the production of anti-drug antibodies (ADAs) which can have clinical consequences. This review includes discussion of the anatomy, physiology, and specific area of the eye that are targeted for drug administration. The various immunologic mechanisms involved in the immune responses to intraocularly administered protein are discussed. This review entails discussion on chemistry, manufacturing, and control (CMC) and formulation-related issues that may influence the risk of immunogenicity. Based on the available immunogenicity profile of the marketed intraocular drugs and their reported adverse events, the animal models and the translational gap from animals to human are discussed. Thus, the objective of this review article is to assess the factors that influence immunogenicity in relation to intraocular administration and the steps taken for mitigating immunogenicity risks.

Alteration in cellular turnover and progenitor cell population in lacrimal glands from thrombospondin 1-/- mice, a model of dry eye.

The purpose of this study was to investigate the changes that occur in the lacrimal glands (LGs) in female thrombospondin 1 knockout (TSP1-/-) mice, a mouse model of the autoimmune disease Sjogren's syndrome. The LGs of 4, 12, and 24 week-old female TSP1-/- and C57BL/6J (wild type, WT) mice were used. qPCR was performed to measure cytokine expression. To study the architecture, LG sections were stained with hematoxylin and eosin. Cell proliferation was measured using bromo-deoxyuridine and immunohistochemistry. Amount of CD47 and stem cell markers was analyzed by western blot analysis and location by immunofluorescence microscopy. Expression of stem cell transcription factors was performed using Mouse Stem Cell Transcription Factors RT2 Profiler PCR Array. Cytokine levels significantly increased in LGs of 24 week-old TSP1-/- mice while morphological changes were detected at 12 weeks. Proliferation was decreased in 12 week-old TSP1-/- mice. Three transcription factors were overexpressed and eleven underexpressed in TSP1-/- compared to WT LGs. The amount of CD47, Musashi1, and Sox2 was decreased while the amount of ABCG2 was increased in 12 week-old TSP1-/- mice. We conclude that TSP1 is necessary for maintaining normal LG homeostasis. Absence of TSP1 alters cytokine levels and stem cell transcription factors, LG cellular architecture, decreases cell proliferation, and alters amount of stem cell markers.

Sjögren's syndrome associated dry eye in a mouse model is ameliorated by topical application of integrin α4 antagonist GW559090.

Sjögren's syndrome is an autoimmune disease associated with inflammation of exocrine glands with clinical manifestations of dry eye and dry mouth. Dry eye in this disease involves inflammation of the ocular surface tissues - cornea and conjunctiva. While systemic blockade of adhesion molecules has been used to treat autoimmune diseases, the purpose of this study was to determine the therapeutic efficacy of topical application of an integrin α4 adhesion molecule antagonist in a mouse model of dry eye associated with Sjögren's syndrome. To assess this spontaneously developed ocular surface inflammation related to Sjögren's syndrome in TSP-1null mice (12 wks) was evaluated. Mice were treated with topical formulations containing 0.1% dexamethasone or 30 mg/ml GW559090 or vehicle control. Corneal fluorescein staining and conjunctival goblet cell density were assessed. Real-time PCR analysis was performed to assess expression of the inflammatory marker IL-1ß in the cornea and Tbet and RORγt in the draining lymph nodes. Ocular surface inflammation was detectable in TSP-1null mice (≥12 wk old), which resulted in increased corneal fluorescein staining indicative of corneal barrier disruption and reduced conjunctival goblet cell density. These changes were accompanied by increased corneal expression of IL-1ß as compared to WT controls and an altered balance of Th1 (Tbet) and Th17 (RORγt) markers in the draining lymph nodes. Topically applied dexamethasone and GW559090 significantly reduced corneal fluorescein staining compared to vehicle treatment (p = 0.023 and p < 0.001, respectively). This improved corneal barrier integrity upon adhesion molecule blockade was consistent with significantly reduced corneal expression of pro-inflammatory IL-1ß compared to vehicle treated groups (p < 0.05 for both treatments). Significant improvement in goblet cell density was also noted in mice treated with 0.1% dexamethasone and GW559090 (p < 0.05 for both). We conclude that similar to topical dexamethasone, topically administered GW559090 successfully improved corneal barrier integrity and inflammation in an established ocular surface disease associated with Sjögren's syndrome.

Thrombospondin-1-dependent immune regulation by transforming growth factor-ß2-exposed antigen-presenting cells.

An important role of transforming growth factor-ß (TGF-ß) in the development of regulatory T cells is well established. Although integrin-mediated activation of latent TGF-ß1 is considered essential for the induction of regulatory T (Treg) cells by antigen-presenting cells (APCs), such an activation mechanism is not applicable to the TGF-ß2 isoform, which lacks an integrin-binding RGD sequence in its latency-associated peptide. Mucosal and ocular tissues harbour TGF-ß2-expressing APCs involved in Treg induction. The mechanisms that regulate TGF-ß activation in such APCs remain unclear. In this study, we demonstrate that murine APCs exposed to TGF-ß2 in the environment predominantly increase expression of TGF-ß2. Such predominantly TGF-ß2-expressing APCs use thrombospondin-1 (TSP-1) as an integrin-independent mechanism to activate their newly synthesized latent TGF-ß2 to induce Foxp3(+) Treg cells both in vitro and in vivo. Expression of Treg induction by TGF-ß2-expressing APCs is supported by a TSP-1 receptor, CD36, which facilitates activation of latent TGF-ß during antigen presentation. Our results suggest that APC-derived TSP-1 is essential for the development of an adaptive regulatory immune response induced by TGF-ß2-expressing APCs similar to those located at mucosal and ocular sites. These findings introduce the integrin-independent mechanism of TGF-ß activation as an integral part of peripheral immune tolerance associated with TGF-ß2-expressing tissues.

TSP-1 Deficiency Alters Ocular Microbiota: Implications for Sjögren's Syndrome Pathogenesis.

PURPOSE: The potential role of commensals as triggering factors that promote inflammation in dry eye disease has not been explored. The objective of this study was to evaluate whether ocular microbiota changes with the onset of dry eye disease in thrombospondin-1-deficient (TSP-1(-/-)) mice, a strain that develops Sjögren's syndrome-like disease. METHODS: Conjunctival swabs were collected from TSP-1(-/-) and C57BL/6 mice and analyzed for bacterial presence. Opsonophagocytosis of the bacterial conjunctival isolates derived from the aged TSP-1(-/-) mice by neutrophils derived from either TSP-1(-/-) or C57BL/6 bone marrow was evaluated. The bactericidal activities of TSP-1-derived peptide were examined. RESULTS: We found that in TSP-1(-/-) mice, the conjunctival colonization with Staphylococcus aureus and coagulase negative staphylococci sp (CNS) species was significantly increased with aging and preceded that of the wild-type C57BL/6 control mice. This correlated with increased neutrophil infiltration into the conjunctiva of the TSP-1(-/-) mice, suggesting that TSP-1 plays a significant role in regulating immunity to commensals. Accordingly, the TSP-1(-/-) PMNs opsonophagocytozed the ocular commensals less efficiently than the TSP-1-sufficient neutrophils. Furthermore, a TSP-1-derived peptide, 4N1K, exhibited significant antimicrobial activity when compared to a control peptide against commensal sp. CONCLUSION: These studies illustrate that alterations in the commensal frequency occur in the early stages of development of Sjögren's-like pathology and suggest that interventions that limit commensal outgrowth such as the use of TSP-1-derived peptides could be used for treatment during the early stages of the disease to reduce the commensal burden and ensuing inflammation.

Inflammatory Cytokine-Mediated Regulation of Thrombospondin-1 and CD36 in Conjunctival Cells.

PURPOSE: Increased expression of transforming growth factor-ß2 (TGF-ß2) is reported in the conjunctiva of dry eye patients with no increase of anti-inflammatory activity of TGF-ß2. Our aim was to compare the expression of molecules involved in TGF-ß2 activation, thrombospondin-1 (TSP-1) and CD36, during murine and human conjunctival inflammation. METHODS: Human conjunctival tissue from cadaveric donors, human conjunctival epithelial primary cells and fibroblasts, and murine conjunctivas were immunostained for TSP-1, CD36, or TGF-ß2. Inflamed conjunctival tissues were obtained from C57BL/6 wild-type (WT) mice induced to develop experimental dry eye (EDE) with 10 days of desiccating conditions and scopolamine injections and TSP-1-deficient (TSP1(-/-)) mice, which spontaneously develop Sjögren's syndrome-associated conjunctival inflammation with age. Immunostaining intensities were compared using ImageJ software. Cultures of human conjunctival fibroblasts were stimulated with IL-1ß and both secreted protein and message levels of TSP-1, CD36, and TGF-ß2 were analyzed. RESULTS: TSP-1 and CD36 were detectable in human and murine conjunctival tissues as well as primary conjunctival epithelial cells and fibroblasts. Increased conjunctival immunostaining of TGF-ß2 and reduced CD36 were detected in EDE mice compared with WT mice. Interestingly, increased TGF-ß2 and CD36 conjunctival immunostaining was detected in TSP1(-/-) mice. The expression of TSP-1 and CD36 was downregulated in IL-1ß-stimulated conjunctival fibroblasts at both the protein and message level, while active TGF-ß2 was undetected. CONCLUSIONS: The absence or reduced expression of either of the molecules involved in TGF-ß2 activation supports proinflammatory conditions in the conjunctiva. Changes in TSP-1 and CD36 may serve as potential biomarkers of conjunctival inflammation.