Inflammatory mediators in autoimmune lacrimal gland disease in MRL/Mpj mice

PURPOSE: MRL/MpJ-fas(+)/fas(+) (MRL/+) and MRL/MpJ-fas(lpr)/fas(lpr) (MRL/lpr) mice are congenic substrains of mice that have spontaneously developing lacrimal and salivary gland inflammation and are models for the human disorder Sj?gren's syndrome. Nitric oxide (NO) and tumor necrosis factor (TNF)-alpha are proinflammatory and potential mediators of tissue damage. The presence of the inducible form of nitric oxide synthase (iNOS), which catalyzes the production of NO, and the presence TNF-alpha in the lacrimal glands of MRL/MpJ mice were assessed. METHODS: Lacrimal glands from MRL/+ and MRL/lpr mice, at ages 1 through 9 months, were evaluated by real-time RT-PCR for iNOS and TNF-alpha mRNA and by immunohistochemistry for the presence of iNOS and of TNF-alpha. Age-matched BALB/c lacrimal glands were used as the control. RESULTS: By quantitative real-time PCR (qPCR), mRNA for iNOS was detected in the lacrimal glands in significantly greater amounts in both MRL/+ (median, normalized to 18S rRNA, 2.90; P < 0.0003) and MRL/lpr mice (median 6.84, P < 0.001) than in BALB/c mice (median 0.34). By qPCR, mRNA for TNF-alpha in the lacrimal glands was detected in significantly greater amounts in aged MRL/+ mice than in BALB/c mice (median, normalized to actin, 221.8 vs. 77.8, P = 0.011) and in MRL/lpr mice than in BALB/c mice (median 136.7 vs. 72.5, P = 0.001). Immunohistochemistry demonstrated both iNOS and TNF-alpha in scattered mononuclear cells throughout the lacrimal glands and in mononuclear cells at the junction of the focal inflammatory infiltrates and normal acinar tissue in both MRL/+ and MRL/lpr mice. CONCLUSIONS: As demonstrated by the greater presence of iNOS and TNF-alpha in the lacrimal glands of MRL/MpJ mice than in control glands, both NO and TNF-alpha are potential mediators of lacrimal gland damage in these murine models of Sj?gren's syndrome.     

Th1 versus Th2 immune responses in autoimmune lacrimal gland disease in MRL/Mp mice

PURPOSE: In MRL/Mp-lpr/lpr (MRL/lpr) and MRL/Mp-+/+ (MRL/+) mice, a T-cell-driven lacrimal gland inflammation spontaneously develops that is a model for Sj?gren's syndrome. The lacrimal gland lesions in these mice were evaluated by immunohistochemistry for the relative contributions of T-helper (Th)1 versus Th2 immune responses. METHODS: Frozen sections of lacrimal glands from MRL/lpr and MRL/+ mice ages 1 through 5 months were stained with monoclonal antibodies to the cytokines interferon (IFN)-gamma and interleukin (IL)4 and to the cell surface costimulatory molecules B7-1 and B7-2, which are associated with Th1 and Th2 responses, respectively. RESULTS: The median proportion of cells staining for IL-4 ranged from 30% to 67% over time for MRL/lpr mice and from 30% to 55% for MRL/+ mice. The median proportion of cells staining for IFN-gamma ranged from 1% to 5% for MRL/lpr mice and from 0% to 3% for MRL/+ mice. The proportion of cells staining positively for IL-4 was significantly greater than for IFN-gamma in both MRL/lpr (mean difference, 33%; P = 0.0001) and MRL/+ mice (mean difference, 42%; P = 0.0002). The median proportion of cells staining positively for B7-2 ranged from 20% to 38% for MRL/lpr mice and from 16% to 34% for MRL/+ mice. The median proportion of cells staining for B7-1 ranged from 2% to 10% for MRL/lpr mice and from 2% to 5% for MRL/+ mice. The proportion of cells staining positively for B7-2 was significantly greater than for B7-1 for both MRL/lpr mice (mean difference, 15%; P = 0.001) and for MRL/+ mice (mean difference, 19%; P = 0.006). CONCLUSIONS: On the basis of immunohistochemistry for cytokines and costimulatory molecules, inflammatory lacrimal gland lesions in MRL/lpr and MRL/+ mice appear to be a largely Th2 phenomenon.     

Impaired neurotransmitter release from lacrimal and salivary gland nerves of a murine model of Sjögren's syndrome

PURPOSE: To determine whether lacrimal and salivary gland nerves of an animal model of Sj?gren's syndrome, the MRL/lpr mouse, are able to release acetylcholine. The second purpose was to determine whether activation of the lacrimal gland nerves of the MRL/lpr mouse leads to protein secretion. METHODS: Total saliva was collected for 10 minutes from the oral cavity of male and female MRL/lpr and MRL/+ mice, after intraperitoneal stimulation with pilocarpine and isoproterenol. Lacrimal and salivary gland lobules prepared from 18-week-old MRL/lpr and MRL/+ mice were incubated in the presence of depolarizing KCl (75 mM) solution. Acetylcholine release and peroxidase secretion (a protein secreted by the lacrimal gland) were measured using a spectrofluorometric assay. RESULTS: Female, but not male, MRL/lpr mouse salivary glands were hyper-responsive to in vivo injection of secretagogues. These mice produced significantly higher amounts of saliva than did age-matched MRL/+ mice. Lacrimal and salivary gland nerves from 18-week-old MRL/+ mice released acetylcholine in response to a depolarizing KCl solution. In contrast, nerves in glands from 18-week-old MRL/lpr mice did not increase acetylcholine release in response to the depolarizing solution. Moreover, lacrimal glands from 18-week-old MRL/+ mice were able to secrete peroxidase in response to a depolarizing KCl solution, whereas those from 18-week-old MRL/lpr could not. This was not due to a defect in the secretory process, because addition of an exogenous secretagogue elicited peroxidase secretion from 18-week-old MRL/lpr as well as MRL/+ mice lacrimal glands. CONCLUSIONS: The results show that activation of nerves of lacrimal and salivary glands infiltrated with lymphocytes does not increase the release of neurotransmitters, which results in impaired secretion from these glands.     

Murine models of Sj?gren's syndrome. Immunohistologic analysis of different strains

Lacrimal gland inflammation develops in several strains of autoimmune mice, including MRL/Mp-lpr/lpr (MRL/lpr), MRL/Mp-+/+ (MRL/+), and NZBxNZW F1 hybrids (NZB/W). These mice all develop an autoimmune disease characterized by glomerulonephritis and autoantibody formation, but each strain has unique clinical features and immunologic abnormalities. Previous studies have suggested that the intrinsic immunologic defect in MRL/lpr mice may be at the level of T cells, while in NZB/W mice it appears to be B cell-mediated. Immunohistologic analysis of the lacrimal gland lesions was performed on all three strains. Although T cells predominated (MRL/lpr 85%, MLR/+ 78%, and NZB/W 57%), differences in the immunohistologic profiles did exist. NZB/W mice had a significantly higher percentage of B cells (33% vs. 10% for MRL/lpr and 13% for MRL/+) and a correspondingly lower percentage of T cells. MRL/lpr mice differed from MRL/+ mice in that they exhibited a significantly higher percentage of helper T cells (63% vs. 49%) and a lower percentage of suppressor/cytotoxic T cells (14% vs. 30%). Class II antigen expression could be detected on the mononuclear cells at inflammatory sites within the lacrimal glands of all three strains, suggesting T cell activation and an active autoimmune immunologic event occurring in the lacrimal gland.     

Murine models of Sj?gren's syndrome. Evolution of the lacrimal gland inflammatory lesions

Lacrimal gland inflammation develops in a number of autoimmune mice, including the MRL/Mp-lpr/lpr (MRL/lpr), MRL/Mp(-)+/+ (MRL/+), and NZB x NZW F1 hybrid (NZB/W) strains. The authors studied the evolution of this process, MRL/lpr mice had inflammatory lesions at 4 weeks old. The lesions had enlarged by 2 months and were fully developed by 4 to 5 months of age. In MRL/+ mice, 4-week-old mice had no lesions, although some focal inflammation was detectable at 3 months old. Significant abnormalities were present at 6 months, and persisted and increased throughout life, with all mice having extensive lesions at 18 months or older. In NZB/W mice, the authors detected no lesions until 6 months of age, and these lesions were fully developed in 9 months. Immunocytochemical profiles, of the cell types infiltrating the lacrimal gland, showed differences not only between the strains, but also in each strain as inflammation progressed. All three types of mice had L3T4+ T cells as the major lymphocyte component, although MRL/+ had significantly more Lyt 2+ T cells than the other strains. NZB/W mice had significantly more B cells than the two MRL substrains. In both NZB/W and MRL/+ mice, there was a significant increase in the B cell population, and a decrease in the percentage of L3T4+ T cells. There was a significant decline in Lyt 2+ T suppressor/cytotoxic cells in both NZB/W and MRL/lpr mice. This last finding was consistent with the more rapid development of inflammation in these strains than in the MRL/+ mice, where Lyt 2+ T suppressor/cytotoxic cells persist. Together, these results indicate that the autoimmune response in murine models of Sj?gren's syndrome is a dynamic, evolving process with strain-related changes in lymphocyte subsets.     

Ocular inflammation in autoimmune MRL/Mp mice

Congenic mice of the MRL/Mp strain spontaneously develop an autoimmune connective tissue disease that shares immunologic and histopathologic features with the human disorders systemic lupus erythematosus, rheumatoid arthritis, and systemic vasculitis. The autoimmune disorder in these mice is markedly accelerated by the recessive gene lpr. Older MRL/Mp-lpr/lpr mice develop significant inflammatory ocular disease, including choroiditis, scleritis, and orbital vasculitis. Animals of both the MRL/Mp-+/+ and MRL/Mp-lpr/lpr substrains develop lacrimal gland inflammatory infiltrates. The MRL/Mp mouse provides a potential model for ocular inflammatory disease and for Sj?gren's syndrome.     

Impact of gender on exocrine gland inflammation in mouse models of Sj?gren's syndrome.

Sj?gren's syndrome is a complex autoimmune disorder, that occurs almost exclusively in females, induces extensive lymphocyte accumulation in lacrimal and salivary glands, and represents one of the leading causes of dry eye and mouth in the world. The purpose of this study was to determine whether the profound, gender-related differences observed in the magnitude of exocrine gland inflammation in Sj?gren's syndrome may also be found in tissues of mouse models of this disorder. Lacrimal and submandibular glands were obtained from adult MRL/lpr, MRL+/+ (MRL+), NZB/NZW F1 (F1), C3H/lpr, C3H/gld (gld), C57BL/6-lpr/lpr [B6/lpr; with (bcl-2(+)/lpr) or without (bcl-2(-)/lpr) bcl-2 transgene insertion] and nonobese diabetic (NOD) mice after the onset of autoimmune disease, and processed for microscopy and image analysis. Our results showed that: (1) the extent of inflammation was significantly greater in lacrimal glands of female MRL/lpr, MRL+, F1, C3H/lpr and gld mice, and salivary glands of female MRL+, F1 and gld mice, relative to those of males; (2) the severity of inflammation in NOD mice showed a tissue-specific pattern: inflammation was far worse in lacrimal glands of males, whereas immune pathology was far greater in salivary tissues in females; and (3) no gender-related variations were present in the degree of inflammation in lacrimal glands of bcl-2(+)/lpr and bcl-2(-)/lpr mice or in submandibular tissues of MRL/lpr, C3H/lpr, bcl-2(+)/lpr and bcl-2(-)/lpr mice. Our findings demonstrate that gender-, strain- and tissue-related differences exist in the extent of inflammation in several mouse models of Sj?gren's syndrome.     

Absence of 4 1BB gene function exacerbates lacrimal gland inflammation in autoimmune-prone MRL-Faslpr mice

PURPOSE: To define the role of endogenous 4-1BB (an important T-cell costimulatory molecule) in the regulation of ocular disease, MRL-Fas(lpr) mice deficient in 4-1BB were generated, and their lacrimal gland function was studied. METHODS: 4-1BB(-/-)MRL/MpJ-Tnfrs(lpr)/Tnfrs(lpr) (lpr/4-1BB(-/-)) mice were generated and used at the ninth backcross. Mice were killed at various times, and lacrimal gland cellularity was analyzed by flow cytometry. Tear and tissue samples were analyzed by Western blotting for the presence of aquaporin 5 (AQP5) and 120-kDa fragments of alpha-fodrin. Cytokine expression of lacrimal glands was assessed by flow cytometry and RT-PCR analysis. RESULTS: Absence of the 4-1BB gene function in lpr mice resulted in early and increased infiltration of mononuclear cells into lacrimal glands compared with 4-1BB intact lpr mice. The severity of lesions in lpr/4-1BB(-/-) mice was closely associated with enhanced accumulation of primarily CD4(+) T cells within the lacrimal glands and with increased expression of IL-4. Elevated levels of AQP5 and cleaved 120-kDa fragments of alpha-fodrin were found in tears and lacrimal gland lysates, respectively, of lpr/4-1BB(-/-) but not lpr/4-1BB(+/+) mice. CONCLUSIONS: Deletion of 4-1BB in lpr mice accelerates lacrimal gland lesions through increased CD4(+) T-cell infiltration and their production of immune modulators.     

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

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

Role of proinflammatory cytokines in the impaired lacrimation associated with autoimmune xerophthalmia

PURPOSE: To determine the effects of the proinflammatory cytokines interleukin (IL)-1alpha, IL-1beta, and tumor necrosis factor (TNF)-alpha on neurally mediated lacrimal gland protein secretion and to determine whether the amount of IL-1beta protein is upregulated in inflamed lacrimal glands of the MRL/lpr mouse, a murine model of human Sj?gren syndrome. METHODS: Lacrimal gland lobules of BALB/c mice were prepared and incubated for 2 hours in the presence or absence of recombinant human (rh)IL-1alpha, rhIL-1beta (10 ng/mL each), or rhTNFalpha (50 ng/mL). Peroxidase secretion in response to depolarizing KCl (75 mM) solution was measured by spectrofluorometric assay. In another set of experiments, saline, rhIL-1beta (1 microg), or an antibody against IL-1 receptor type I (IL-1RI), with or without rhIL-1beta, was injected (2 microL) into the lacrimal glands of anesthetized BALB/c mice. Twenty-four hours later, lacrimal gland lobules were prepared and peroxidase secretion was measured. The amount of IL-1beta protein in lacrimal gland acinar cell lysates prepared from 3-, 9-, and 13-week-old BALB/c, MRL/(+), and MRL/lpr mice was determined by ELISA. RESULTS: KCl-induced peroxidase secretion was inhibited in vitro 62%, 66%, and 53% by rhIL-1alpha, rhIL-1beta, and rhTNFalpha, respectively. In vivo, rhIL-1beta inhibited KCl-induced peroxidase secretion by 72%. This inhibitory effect of IL-1beta was completely reversed by an antibody against IL-1RI. Compared with 3-week-old mice, the amount of IL-1beta protein was upregulated 15- and 21-fold in lacrimal gland acinar cells isolated from 9- and 13-week-old MRL/lpr mice, respectively. CONCLUSIONS: Proinflammatory cytokines inhibit neurally mediated lacrimal gland secretion. The amount of IL-1beta protein is upregulated in acinar cells prepared from lacrimal glands infiltrated with lymphocytes. These results suggest that elevated levels of IL-1beta, as they occur in Sj?gren syndrome exocrine glands, may impair the secretory function of these tissues.     

Involvement of apoptosis and interferon-gamma in murine toxoplasmosis

PURPOSE: A murine toxoplasmosis model has been developed that results in central nervous system (CNS) and ocular inflammation characterized by encephalitis with numerous brain tissue cysts and milder inflammation with rare tissue cysts in the eye after 4 weeks of Toxoplasma gondii infection. In this model IFN gamma and inducible nitric oxide (iNO) are protective against T. gondii infection. In this study, the role of apoptosis in the pathogenesis of toxoplasmosis was investigated. METHODS: C57BL/6 (wild-type mice), B6MRL/lpr, and B6MRL/gld (defective Fas or FasL expression, respectively) mice were infected intraperitoneally with 20 to 30 tissue cysts of the ME-49 strain of T. gondii. Mice were killed at days 0, 14, or 28 after infection. The eyes and brains were harvested for histologic, immunohistochemical, and molecular studies. Analysis included immunostaining for Fas, FasL, Bcl-2, and Bax; in situ apoptosis detection (TUNEL assay); RT-PCR amplification for IFN gamma; and measurement of ocular nitrite levels. The control mice were na?ve mice of each strain that received no inoculation or injection. RESULTS: Wild-type mice appeared to constitutively express apoptotic molecules at higher levels in the eye than in the brain. Consequently, during T. gondii infection, apoptosis was greater in the eyes than in the brain. Untreated na?ve lpr and gld mice showed no expression of Fas and FasL, respectively. After infection, a slightly higher number of tissue cysts (lpr, 11.8 +/- 2.4; gld, 10.3 +/- 3.4) were found in the brains of the mutants than in the control animals (8.8 +/- 2.9). However, no significant differences between the number of apoptotic cells, inflammatory scores, or number of tissue cysts were noted in the eyes. IFN gamma mRNA in control mice was detected at day 28 after infection, whereas in both mutants, mRNA production occurred earlier, at day 14. Ocular nitrite levels were higher in lpr and gld mice than in wild-type mice. CONCLUSIONS: No significant difference in the degree of ocular inflammation and apoptosis was detected between the wild-type and Fas or FasL mutant mice. However, there was an earlier and subjectively greater expression of IFN gamma in the brain and eye and a higher level of nitrite in the ocular tissue of mutant strains than in the wild type. Multiple factors are likely to be involved in the pathogenesis of ocular toxoplasmosis.     

Impact of androgen therapy in Sj?gren's syndrome: hormonal influence on lymphocyte populations and Ia expression in lacrimal glands of MRL/Mp-lpr/lpr mice.

Recent research has demonstrated that androgen treatment dramatically curtails lymphocyte infiltration in the lacrimal glands of a mouse model of Sj?gren's syndrome. The purpose of the current study was to determine whether this androgen action involves the selective suppression of specific lymphocyte populations or Ia expression in lacrimal tissue. Autoimmune female MRL/Mp-lpr/lpr mice were administered placebo- or testosterone-containing compounds for 0, 17, or 34 d. Then lacrimal glands were obtained and processed for immunohistochemical evaluation. Results demonstrated that in pretreatment mice, lacrimal lymphoid foci were composed predominantly of Thy 1.2+ cells, bearing L3T4 (helper T cell) or B220 surface antigens. In contrast, suppressor T cells (Lyt 2+) and surface IgM-bearing B cells represented minority populations in the immune infiltrates. Class II antigen (Ia) expression was observed on over 40% of the infiltrate lymphocytes and occasionally on epithelial cells close to the lymphoid focus. During the experimental time course, the extent of lymphocyte infiltration increased in glands of placebo-treated mice. This cellular accumulation was associated with an elevation in the frequency of B220+ cells, but not that of other lymphocyte subclasses. Testosterone administration induced a striking diminution in the area encompassed by all immune cell populations. Moreover, hormone therapy significantly reduced the frequency of B220+ cells in focal infiltrates. Overall, these findings demonstrate that androgen exposure stimulates a decrease in the quantity, but not necessarily the entire lymphocyte composition, of lymphoid aggregates in lacrimal glands of MRL/lpr mice.     

Lymphocytic infiltration and goblet cell marker alteration in the conjunctiva of the MRL/MpJ-Fas(lpr) mouse model of Sjögren's syndrome

Sj?gren's syndrome is an autoimmune disorder characterized by a progressive, immune-mediated destruction of mucosal tissues such as the lacrimal and salivary glands, leading to ocular and oral dryness. The MRL/MpJ-Fas(lpr) mouse is one of the animal models used to study this disease. However, little is known about the potential alterations in the conjunctiva in this murine model. The purpose of this study was to determine: (1) whether the conjunctiva is infiltrated by T lymphocytes, (2) characterize the type, amount and temporal sequence of the inflammatory infiltrates, and (3) investigate whether the amount of conjunctival goblet cells is altered in this murine model of Sj?gren's syndrome. Female 4-, 9-, 13-, 16-, and 18-/20-wk-old MRL/MpJ-Fas(lpr) (lpr, diseased) and congenic MRL/MpJ (+/+, control) mice were used. Right eyes were either fixed, frozen, cryosectioned, and studied by immunofluorescence microscopy or the conjunctiva was removed, homogenized and analyzed by electrophoresis and Western blot analysis. The following antibodies were used: anti-CD3 (specific T lymphocyte marker), anti-cytokeratin 7 (CK-7), anti-PKD (formerly known as PKCmu, both markers of goblet cell bodies), anti-PGP 9.5 (pan-neuronal marker), anti-VIP and TH (markers for parasympathetic and sympathetic nerves, respectively), anti-adrenergic (alpha(1) and beta(1-3)) and muscarinic (M(1)-M(3)) receptor subtypes (markers for neurotransmitter receptors of the sympathetic and parasympathetic pathways, respectively). Left eyes were fixed, embedded, sectioned, and stained. Hematoxylin/eosin, Giemsa, or alcian blue/periodic acid Schiff's reagent were used to study lymphocyte infiltration; to determine the presence of eosinophils, neutrophils, and mast cells; and to count the number of goblet cells, respectively. By immunofluorescence microscopy, lymphocytes were detected in the conjunctiva of 9-wk-old lpr, but not +/+, mice. The lymphocytic infiltration became more extensive as the animals aged, with 16- and 18-/20-wk lpr mice appearing to have a greater lymphocytic infiltration than +/+ mice at the same age. By Western blot analysis, the amount of CD3 was enhanced in lpr compared to +/+ mice by the 16th wk, but not by the 9th wk. No major differences in the presence of eosinophils, neutrophils and degranulated mast cells between lpr and +/+ mice were observed. By light microscopy, a significant increase in goblet cell number was found in lpr mice compared to +/+ mice at 16 wks on. By Western blotting, the amount of CK-7 was significantly increased at 9 wks on and the amount of PKD was significantly increased at 16 wks. By immunofluorescence microscopy, there were no major differences in distribution of sympathetic and parasympathetic nerves present in the lpr conjunctiva compared to that of +/+ mice at any ages, although slight differences were observed with increased age. Muscarinic receptor expression was decreased, as less M(3) receptor subtype-associated immunofluorescence was detected in older lpr mice compared to +/+ mice and confirmed by Western blot analysis. No differences in the localization or the amount of alpha(1)- or beta(1-3)-adrenergic receptor immunodetection were observed between lpr and +/+ mice. We conclude that the conjunctiva is a target tissue in Sj?gren's syndrome-related inflammation in this murine model.     

Leakage of aquaporin 5 in the tear of dacryoadenitis mice

PURPOSE: The objective of this study was to investigate whether leakage of aquaporin 5 (AQP5) in tear is associated with damage of lacrimal glands (LGs) in dacryoadenitis models. METHODS: Female MRL/lpr (24-week-old), male NOD/Shi Jci (5-, 8-, and 10-week-old), female NFS/s-TX (10-week-old), and lipopolysaccharide (LPS)-induced dacryoadenitis model mice were used. Tear fluid was collected by a cotton thread. Tear proteins in the thread were dissolved in sodium dodecyl sulfate buffer, and AQP5 proteins were analyzed by the Western blot technique using anti-AQP5 antibody. LGs were prepared for hematoxylin and eosin staining or immunostaining of AQP5. RESULTS: In MRL/lpr, NFS/s-TX, 8- and 10-week-old NOD/Shi Jci mice, AQP5 protein was detected in the tear by Western blot analysis. Inflammatory lymphocyte infiltrations were observed in LGs of these dacryoadenitis model mice. In contrast, AQP5 leakage and damage of LG were not observed in normal mice. In 5-week-old NOD/Shi Jci mice, infiltration was not seen in LG, and AQP5 leakage was not detected in the tear. In LPS-induced dacryoadenitis model mice, either tissue destruction with inflammation in LG or AQP5 leakage in the tear was observed. AQP5 in the tear and tissue inflammation in LGs was not found in control mice. These results indicate that AQP5 is leaked in tears when LGs are damaged by dacryoadenitis. CONCLUSIONS: Leakage of AQP5 in the tear was found to be related to LG damage. This finding suggests that detection of AQP5 in tear is useful for specific diagnosis of LG disorders with tissue destruction.     

Influence of sex hormones and genetic predisposition in Sjögren's syndrome: a new clue to the immunopathogenesis of dry eye disease

Sj?gren's syndrome (SS) is a chronic autoimmune disease characterized by lymphocytic infiltration, destruction of lacrimal and salivary glands and the presence of serum autoantibodies. Most women that suffer from SS are post-menopausal however, not all post-menopausal women develop SS, suggesting that other factors, in addition to the decrease in ovarian hormones, are necessary for the development of SS. The purposes of this study were to investigate a) the time course of lymphocytic infiltration and apoptosis in the lacrimal gland after ovariectomy, b) if a predisposed genetic background for SS aggravates the effects of decreasing levels of sex hormones in the lacrimal glands and c) if physiological doses of estrogen or androgen prevent the effects observed after ovariectomy. Six weeks old mice that are genetically predisposed to SS (NOD.B10.H2(b)) and control (C57BL/10) mice were either sham operated, ovariectomized (OVX), OVX?+?17β estradiol (E(2)) or OVX?+?Dihydrotestosterone (DHT). Lacrimal glands were collected at 3, 7, 21 or 30 days after surgery and processed for immunohistochemistry to measure CD4(+), CD8(+) T cells, B220(+) B cells, nuclear DNA degradation and cleaved caspase-3 activity. Quantification of the staining was done by light microscopy and Image Pro Plus software. The results of our study show that lymphocytic infiltration preceded lacrimal gland apoptosis after ovariectomy. Moreover, removal of ovarian sex hormones accelerated these effects in the genetically predisposed animal and these effects were more severe and persistent compared to control animals. In addition, sex hormone replacement at physiological levels prevented these symptoms. The mechanisms by which decreased levels of sex hormones caused lymphocytic infiltration and apoptosis and the interaction of lack of sex hormones with the genetic elements remain to be elucidated.     

Apoptosis and related gene expression in lacrimal gland of cases with Sjögren's syndrome

OBJECTIVE: To assess the roles of apoptosis and expression of the related genes in lacrimal glandular destruction of patients with Sj?gren's syndrome (SS). METHODS: Small pieces of palpebral lobes of lacrimal glands were obtained from 12 patients (10 with primary Sj?gren's syndrome, 2 with secondary Sj?gren's syndrome) and 7 normal controls. They had been investigated by the in situ end labeling and immunohistochemical staining to detect the apoptotic cells and the expression of Fas, FasL, bcl-2 and Bax. RESULTS: The number of epithelial apoptotic cells in lacrimal glands of patients with SS was significantly higher than that in normal glands, and SS epithelial cells showed increased expression of Fas, FasL and Bax. There was significant positive correlation between the number of the apoptotic cells and that of the cells expressing Fas, FasL and Bax, respectively, and there was significant negative correlation between the number of the apoptotic cells and that of the cells expressing bcl-2. CONCLUSIONS: The apoptosis of the epithelial cells in the lacrimal gland may be one of the mechanisms leading to the glandular destruction found in SS. In SS lacrimal glands, the expression of Fas, FasL and Bax may promote apoptosis, and the expression of bcl-2 may inhibit apoptosis.     

Age-dependent alterations in mouse exorbital lacrimal gland structure, innervation and secretory response

Several studies investigated the effect of aging on rat and human lacrimal gland physiology. However, in most of these studies, only two age groups were investigated. Furthermore, those studies did not correlate the age-related histological changes that occur in the lacrimal gland to the functional changes (nerve activity and protein secretion) that might occur with aging. Thus, the purpose of the present study was to investigate the effect of aging on lacrimal gland structure, innervation and function using BALB/c mice at different ages. Exorbital lacrimal glands were removed from 3, 8, 12, 24, and 32-month-old, male BALB/c mice, fixed, embedded and processed for histology and immunohistochemistry. Sections were stained with hematoxylin and eosin to determine morphological changes and lymphocytic infiltration; giemsa to identify mast cells; and Kinyoun's carbol fucsin solution to indicate lipofuscin-like inclusions. Parasympathetic and sympathetic nerves were identified by immunofluorescence techniques. To measure acetylcholine release and protein secretion, lacrimal gland pieces were incubated in Krebs Ringer buffer containing 5 mM KCl (control), 75 mM KCl (depolarizing buffer which activates nerves), carbachol (a cholinergic agonist, 10(-4) M), or phenylephrine (an alpha1-adrenergic agonist, 10(-4) M) for 20 min. The media were collected and analysed for acetylcholine and peroxidase using a spectrofluorometric assay. KCl-, carbachol- and phenylephrine-stimulated peroxidase secretion decreased in lacrimal glands from 8, 12, and 24-month-old mice when compared to 3-month-old animals. Both the density and distribution of parasympathetic and sympathetic nerves surrounding the acini decreased with increasing age. Acetylcholine release from lacrimal gland nerves decreased in 24-month-old mice compared to 3- and 12-month-old animals. Similarly, progressive morphological changes, including increased numbers of lipofuscin-like inclusions, mast cells and lymphocytic infiltration occurred in an age-dependent manner. We conclude that structural alterations of mouse lacrimal gland, including increased accumulation of lipofuscin-like inclusions, chronic inflammation and functional alterations including decreased acetylcholine release and protein secretion occurred with aging.