Aire-deficient mice provide a model of corneal and lacrimal gland neuropathy in Sjogren's syndrome.
ABSTRACT: Sjögren's syndrome (SS) is a chronic, autoimmune exocrinopathy that leads to severe dryness of the mouth and eyes. Exocrine function is highly regulated by neuronal mechanisms but little is known about the link between chronic inflammation, innervation and altered exocrine function in the diseased eyes and exocrine glands of SS patients. To gain a better understanding of neuronal regulation in the immunopathogenesis of autoimmune exocrinopathy, we profiled a mouse model of spontaneous, autoimmune exocrinopathy that possess key characteristics of peripheral neuropathy experienced by SS patients. Mice deficient in the autoimmune regulator (Aire) gene developed spontaneous, CD4+ T cell-mediated exocrinopathy and aqueous-deficient dry eye that were associated with loss of nerves innervating the cornea and lacrimal gland. Changes in innervation and tear secretion were accompanied by increased proliferation of corneal epithelial basal cells, limbal expansion of KRT19-positive progenitor cells, increased vascularization of the peripheral cornea and reduced nerve function in the lacrimal gland. In addition, we found extensive loss of MIST1+ secretory acinar cells in the Aire -/- lacrimal gland suggesting that acinar cells are a primary target of the disease, Finally, topical application of ophthalmic steroid effectively restored corneal innervation in Aire -/- mice thereby functionally linking nerve loss with local inflammation in the aqueous-deficient dry eye. These data provide important insight regarding the relationship between chronic inflammation and neuropathic changes in autoimmune-mediated dry eye. Peripheral neuropathies characteristic of SS appear to be tightly linked with the underlying immunopathological mechanism and Aire -/- mice provide an excellent tool to explore the interplay between SS-associated immunopathology and peripheral neuropathy.
Project description:Sjögren's syndrome (SS) is characterized by extensive lymphocytic infiltration of the salivary and lacrimal gland (LG), resulting in acinar cell destruction and organ dysfunction. The underlying pathogenesis of SS remains largely unknown, and studies historically focus on defining late-stage disease. Here, we identify tissue programs associated with disease onset using transcriptomic and immunohistological analysis of LGs from 5- and 7-week-old mice deficient in autoimmune response element (Aire). At 5 weeks of age (wk), Aire-/- mice show minimal tissue dysfunction and destruction compared to 7 wk Aire-/-, which exhibit severe dry eye, poor tear secretion, extensive lymphocytic infiltration, reduced functional innervation, and increased vascularization. Despite this mild phenotype, 5 wk Aire-/- LGs were highly enriched for signaling pathways previously associated with SS, including interferon gamma (IFN?), interleukin 1 beta (IL1?), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-?B), toll-like receptor (TLR) signaling, and interleukin-6/signal transducer and activator of transcription 3 (IL6/STAT3) signaling. Novel signaling pathways such as the semaphorin?plexin pathway were also noted. Intriguingly, we found an expansion of the ductal network with increasing disease. Activated STAT3, a blocker of apoptosis, was restricted to the ductal system and also increased with damage, highlighting its potential as a promoter of ductal cell survival. These data demonstrate the early activation of signaling pathways regulating inflammation, innervation, and cell survival before the onset of clinical disease indicators, suggesting their potential value as diagnostic biomarkers.
Project description:Sjögren's Syndrome (SS) is a human autoimmune disease characterized by immune-mediated destruction of the lacrimal and salivary glands. In this study, we show that the Aire-deficient mouse represents a new tool to investigate autoimmune dacryoadenitis and keratoconjunctivitis sicca, features of SS. Previous work in the Aire-deficient mouse suggested a role for alpha-fodrin, a ubiquitous Ag, in the disease process. Using an unbiased biochemical approach, however, we have identified a novel lacrimal gland autoantigen, odorant binding protein 1a, targeted by the autoimmune response. This novel autoantigen is expressed in the thymus in an Aire-dependent manner. The results from our study suggest that defects in central tolerance may contribute to SS and provide a new and clinically relevant model to investigate the pathogenic mechanisms in lacrimal gland autoimmunity and associated ocular surface sequelae.
Project description:Sjögren's syndrome (SjS) is a human autoimmune disease characterized by exocrine dysfunction resulting from chronic autoimmune attack primarily against the lacrimal and/or salivary glands. Although, we previously established a good correlation between SjS in humans and autoimmune exocrinopathy in NOD/LtJ mice an in-depth evaluation of lacrimal gland disease in the NOD/LtJ mouse has remained limited. This leaves a major gap in our understanding of the dacryoadenitis/keratoconjunctivitis sicca in this model. Here we characterize the development of the autoimmune dacryoadenitis in NOD/LtJ and NOD.B10-H2(b) mice in comparison with age- and sex-matched nonautoimmune CD1 mice. We observed a decline in tear production beginning at 8 weeks of age in both NOD/LtJ and NOD.B10-H2(b) mice, continuing throughout the 40 to 46 weeks studied. This correlated with a quantifiable increase in mixed T- and B-lymphocyte infiltrations in the extraorbital lacrimal glands. In addition, temporal differences in tear protein expression between NOD/LtJ and CD1 mice were identified using two-dimensional gel electrophoresis and tandem mass spectrometry. Thus, using this model we can identify potentially important pathophysiological mechanisms of the autoimmune attack and possible diagnostic markers for development of SjS-associated dacryoadenitis.
Project description:Chronic inflammation of the ocular surface in Sjögren's syndrome (SS) is associated with a vision-threatening, phenotypic change of the ocular surface, which converts from a nonkeratinized, stratified squamous epithelium to a nonsecretory, keratinized epithelium. This pathological process is known as squamous metaplasia. Based on a significant correlation between ocular surface interleukin (IL)-1beta expression and squamous metaplasia in patients with SS, we investigated the role of IL-1 in the pathogenesis of squamous metaplasia in an animal model that mimics the clinical characteristics of SS. Using autoimmune-regulator (aire)-deficient mice, we assessed lacrimal gland and ocular surface immunopathology by quantifying the infiltration of major histocompatibility complex class II(+) (I-A(d+)) dendritic cells and CD4(+) T cells. We examined squamous metaplasia using a biomarker of keratinization, small proline-rich protein 1B. We used lissamine green staining as a readout for ocular surface epitheliopathy and Alcian blue/periodic acid-Schiff histochemical analysis to characterize goblet cell muco-glycoconjugates. Within 8 weeks, the eyes of aire-deficient mice were pathologically keratinized with significant epithelial damage and altered mucin glycosylation. Although knockdown of IL-1 receptor 1 did not attenuate lymphocytic infiltration of the lacrimal gland or eye, it significantly reduced ocular surface keratinization, epitheliopathy, and muco-glycoconjugate acidification. These data demonstrate a phenotypic modulation role for IL-1 in the pathogenesis of squamous metaplasia and suggest that IL-1 receptor 1-targeted therapies may be beneficial for treating ocular surface disease associated with SS.
Project description:Autoimmune polyendocrinopathy syndrome type 1 (APS1) results from homozygous Aire mutations that cripple thymic deletion of organ-specific T cells. The clinical course in man and mouse is characterized by high variability both in the latent period before onset of autoimmune disease and in the specific organs affected, but the reasons for this are unknown. Here we test the hypothesis that the latent period reflects the failsafe action of discrete postthymic mechanisms for imposing self-tolerance in peripheral T cells. Aire-deficient mice were crossed with mice of a uniform major histocompatibility complex (MHC) haplotype and genetic background carrying specific genetic defects in one of four distinct peripheral tolerance mechanisms: activation-induced cell death (Fasl(gld/gld)), anergy and requirement for CD28 costimulation (Cblb(-/-)), inhibition of ICOS and T(FH) cells (Rc3h1(san/san)), or decreased numbers of Foxp3(+) T regulatory cells (Card11(unm/unm)). Cblb-deficiency was unique among these four in precipitating rapid clinical autoimmune disease when combined with Aire-deficiency, resulting in autoimmune exocrine pancreatitis with median age of survival of only 25 d. Massive lymphocytic infiltration selectively destroyed most of the exocrine acinar cells of the pancreas and submandibular salivary gland, and CD4(+) and CD8(+) subsets were necessary and sufficient to transfer the disease. Intrinsic regulation of peripheral T cells by CBL-B thus serves a uniquely critical role as a failsafe against clinical onset of autoimmune disease in AIRE deficiency, and multiple peripheral tolerance mechanisms may need to fail before onset of clinical autoimmunity to many organs.
Project description:Sjögren's syndrome is a chronic autoimmune process that primarily affects the exocrine glands and leads to their functional impairment. The exocrine gland involvement is characterized by a focal, mononuclear cell infiltrate which is accumulated around ducts and, in some patients, extends and replaces the secretory functional units. The mechanisms of this autoimmune 'exocrinopathy' are not fully understood. The immune attack that follows activation or apoptosis of glandular epithelial cells exposing autoantigens in genetically predisposed individuals may drive the immune-mediated tissue injury. Abnormalities related to the upregulation of type I interferon-regulated genes (interferon signature), abnormal expression of B-cell-activating factor (BAFF) and activation of the IL-23/TH17 pathway are among the immune mediators implicated in the pathogenesis of autoimmune lesions within the salivary glands. Such abnormalities demonstrate the complex interplay between innate and adaptive immunity that contributes to autoimmune 'exocrinopathy'.
Project description:BACKGROUND: Migration of T cells, including regulatory T (Treg) cells, into the secondary lymph organs is critically controlled by chemokines and adhesion molecules. However, the mechanisms by which Treg cells regulate organ-specific autoimmunity via these molecules remain unclear. Although we previously reported autoimmune exocrinopathy resembling Sjögren's syndrome (SS) in the lacrimal and salivary glands from C-C chemokine receptor 7 (CCR7)-deficient mice, it is still unclear whether CCR7 signaling might specifically affect the dynamics and functions of Treg cells in vivo. We therefore investigated the cellular mechanism for suppressive function of Treg cells via CCR7 in autoimmunity using mouse models and human samples. METHODS AND FINDINGS: Patrolling Treg cells were detected in the exocrine organs such as lacrimal and salivary glands from normal mice that tend to be targets for autoimmunity while the Treg cells were almost undetectable in the exocrine glands of CCR7(-/-) mice. In addition, we found the significantly increased retention of CD4(+)CD25(+)Foxp3(+) Treg cells in the lymph nodes of CCR7(-/-) mice with aging. Although Treg cell egress requires sphingosine 1-phosphate (S1P), chemotactic function to S1P of CCR7-/- Treg cells was impaired compared with that of WT Treg cells. Moreover, the in vivo suppression activity was remarkably diminished in CCR7(-/-) Treg cells in the model where Treg cells were co-transferred with CCR7(-/-) CD25(-)CD4(+) T cells into Rag2(-/-) mice. Finally, confocal analysis showed that CCR7(+)Treg cells were detectable in normal salivary glands while the number of CCR7(+)Treg cells was extremely decreased in the tissues from patients with Sjögren's syndrome. CONCLUSIONS: These results indicate that CCR7 essentially governs the patrolling functions of Treg cells by controlling the traffic to the exocrine organs for protecting autoimmunity. Characterization of this cellular mechanism could have clinical implications by supporting development of new diagnosis or treatments for the organ-specific autoimmune diseases such as Sjögren's syndrome and clarifying how the local immune system regulates autoimmunity.
Project description:Keratinizing squamous metaplasia (SQM) of the ocular mucosal epithelium is a blinding corneal disease characterized by the loss of conjunctival goblet cells (GCs), pathological ocular surface keratinization and tissue recruitment of immune cells. Using the autoimmune regulator (Aire)-deficient mouse as a model for Sjögren's syndrome (SS)-associated SQM, we identified CD4(+) T lymphocytes as the main immune effectors driving SQM and uncovered a pathogenic role for interleukin-1 (IL-1). IL-1, a pleiotropic cytokine family enriched in ocular epithelia, governs tissue homeostasis and mucosal immunity. Here, we used adoptive transfer of autoreactive CD4(+) T cells to dissect the mechanism whereby IL-1 promotes SQM. CD4(+) T cells adoptively transferred from both Aire knockout (KO) and Aire/IL-1 receptor type 1 (IL-1R1) double KO donors conferred SQM to severe-combined immunodeficiency (scid) recipients with functional IL-1R1, but not scid recipients lacking IL-1R1. In the lacrimal gland, IL-1R1 was primarily immunolocalized to ductal epithelium surrounded by CD4(+) T cells. In the eye, IL-1R1 was expressed on local mucosal epithelial and stromal cells, but not on resident antigen-presenting cells or infiltrating immune cells. In both tissues, autoreactive CD4(+) T-cell infiltration was only observed in the presence of IL-1R1-postive resident cells. Moreover, persistent activation of IL-1R1 signaling led to chronic immune-mediated inflammation by retaining CD4(+) T cells in the local microenvironment. Following IL-1R1-dependent infiltration of CD4(+) T cells, we observed SQM hallmarks in local tissues-corneal keratinization, conjunctival GC mucin acidification and epithelial cell hyperplasia throughout the ocular surface mucosa. Proinflammatory IL-1 expression in ocular epithelial cells significantly correlated with reduced tear secretion, while CD4(+) T-cell infiltration of the lacrimal gland predicted the development of ocular SQM. Collectively, data in this study indicated a central role for IL-1 in orchestrating a functional interplay between immune cells and resident cells of SS-targeted tissues in the pathogenesis of SQM.
Project description:Sjögren's Syndrome (SS) is an autoimmune exocrinopathy characterized by the progressive damage of salivary and lacrimal glands associated with lymphocytic infiltration. It can be defined as primary SS (pSS) or associated/secondary SS (sSS) if combined with another systemic autoimmune disease. Identifying new non-invasive biomarkers for SS diagnosis remains a challenge, and alterations in saliva composition reported in patients turn this fluid into a source of potential biomarkers. To examine the overall panorama of proteins in saliva, samples of control, pSS, and sSS individuals were analyzed by gel-free LC-MS/MS.
Project description:Sjögren's Syndrome (SS) is an autoimmune exocrinopathy characterized by the progressive damage of salivary and lacrimal glands associated with lymphocytic infiltration. It can be defined as primary SS (pSS) or associated/secondary SS (sSS) if combined with another systemic autoimmune disease. Identifying new non-invasive biomarkers for SS diagnosis remains a challenge, and alterations in saliva composition reported in patients turn this fluid into a source of potential biomarkers. To examine the overall panorama of proteins in saliva, samples of control, pSS, and sSS individuals were analyzed by gel-based LC-MS/MS.