Akt Signaling Pathway Is Activated in the Minor Salivary Glands of Patients with Primary Sjögren's Syndrome.

Primary Sjögren's syndrome (pSS) is an autoimmune exocrinopathy of mainly the salivary and lacrimal glands associated with high prevalence of lymphoma. Akt is a phosphoinositide-dependent serine/threonine kinase, controlling numerous pathological processes, including oncogenesis and autoimmunity. Herein, we sought to examine its implication in pSS pathogenesis and related lymphomagenesis. The expression of the entire and activated forms of Akt (partially and fully activated: phosphorylated at threonine-308 (T308) and serine-473 (S473), respectively), and two of its substrates, the proline-rich Akt-substrate of 40 kDa (PRAS40) and FoxO1 transcription factor has been immunohistochemically examined in minor salivary glands (MSG) of pSS patients (n = 29; including 9 with pSS-associated lymphoma) and sicca-complaining controls (sicca-controls; n = 10). The entire and phosphorylated Akt, PRAS40, and FoxO1 molecules were strongly, uniformly expressed in the MSG epithelia and infiltrating mononuclear cells of pSS patients, but not sicca-controls. Morphometric analysis revealed that the staining intensity of the fully activated phospho-Akt-S473 in pSS patients (with or without lymphoma) was significantly higher than sicca-controls. Akt pathway activation was independent from the extent or proximity of infiltrates, as well as other disease features, including lymphoma. Our findings support that the Akt pathway is specifically activated in MSGs of pSS patients, revealing novel therapeutic targets.

Increased Indoleamine 2,3-Dioxygenase Levels at the Onset of Sjögren's Syndrome in SATB1-Conditional Knockout Mice.

Sjögren's syndrome (SS) is a chronic autoimmune disease characterized by dysfunction of salivary and lacrimal glands, resulting in xerostomia (dry mouth) and keratoconjunctivitis sicca (dry eyes). Autoantibodies, such as anti-SSA and anti-SSB antibodies, are hallmarks and important diagnostic factors for SS. In our previous study, we demonstrated that SS-like xerostomia was observed in SATB1 conditional knockout (SATB1cKO) mice, in which the floxed SATB1 gene was specifically deleted in hematopoietic cells as early as 4 weeks of age. In these mice, autoantibodies were not detected until 8 weeks of age in SATB1cKO mice, although exocrine gland function reached its lowest at this age. Therefore, other markers may be necessary for the diagnosis of SS in the early phase. Here, we found that mRNA expression of the interferonγ (IFN-γ) gene and the IFN-responsive indoleamine 2,3-dioxygenase (IDO) gene is upregulated in the salivary glands of SATB1cKO mice after 3 and 4 weeks of age, respectively. We detected l-kynurenine (l-KYN), an intermediate of l-tryptophan (l-Trp) metabolism mediated by IDO, in the serum of SATB1cKO mice after 4 weeks of age. In addition, the upregulation of IDO expression was significantly suppressed by the administration of IFN-γ neutralizing antibodies in SATB1cKO mice. These results suggest that the induction of IFN-dependent IDO expression is an initial event that occurs immediately after the onset of SS in SATB1cKO mice. These results also imply that serum l-KYN could be used as a marker for SS diagnosis in the early phases of the disease before autoantibodies are detectable.

Deregulation of the Kallikrein Protease Family in the Salivary Glands of the Sjögren's Syndrome ERdj5 Knockout Mouse Model.

Introduction: The purpose of this study was to identify differentially expressed proteins in salivary glands of the ERdj5 knockout mouse model for Sjögren's syndrome and to elucidate possible mechanisms for the morbid phenotype development. At the same time, we describe for the first time the sexual dimorphism of the murine submandibular salivary gland at the proteome level. Methods: We performed Liquid Chromatography/Mass Spectrometry in salivary gland tissues from both sexes of ERdj5 knockout and 129SV wildtype mice. The resulting list of proteins was evaluated with bioinformatic analysis and selected proteins were validated by western blot and immunohistochemistry and further analyzed at the transcription level by qRT-PCR. Results: We identified 88 deregulated proteins in females, and 55 in males in wildtype vs knockout comparisons. In both sexes, Kallikrein 1b22 was highly upregulated (fold change>25, ANOVA p<0.0001), while all other proteases of this family were either downregulated or not significantly affected by the genotype. Bioinformatic analysis revealed a possible connection with the downregulated NGF that was further validated by independent methods. Concurrently, we identified 416 proteins that were significantly different in the salivary gland proteome of wildtype female vs male mice and highlighted pathways that could be driving the strong female bias of the pathology. Conclusion: Our research provides a list of novel targets and supports the involvement of an NGF-mediating proteolytic deregulation pathway as a focus point towards the better understanding of the underlying mechanism of Sjögren's syndrome.

Upregulated Chemokine and Rho-GTPase Genes Define Immune Cell Emigration into Salivary Glands of Sjögren's Syndrome-Susceptible C57BL/6.NOD-Aec1Aec2 Mice.

The C57BL/6.NOD-Aec1Aec2 mouse is considered a highly appropriate model of Sjögren's Syndrome (SS), a human systemic autoimmune disease characterized primarily as the loss of lacrimal and salivary gland functions. This mouse model, as well as other mouse models of SS, have shown that B lymphocytes are essential for the development and onset of observed clinical manifestations. More recently, studies carried out in the C57BL/6.IL14α transgenic mouse have indicated that the marginal zone B (MZB) cell population is responsible for development of SS disease, reflecting recent observations that MZB cells are present in the salivary glands of SS patients and most likely initiate the subsequent loss of exocrine functions. Although MZB cells are difficult to study in vivo and in vitro, we have carried out an ex vivo investigation that uses temporal global RNA transcriptomic analyses to profile differentially expressed genes known to be associated with cell migration. Results indicate a temporal upregulation of specific chemokine, chemokine receptor, and Rho-GTPase genes in the salivary glands of C57BL/6.NOD-Aec1Aec2 mice that correlate with the early appearance of periductal lymphocyte infiltrations. Using the power of transcriptomic analyses to better define the genetic profile of lymphocytic emigration into the salivary glands of SS mice, new insights into the underlying mechanisms of SS disease development and onset begin to come into focus, thereby establishing a foundation for further in-depth and novel investigations of the covert and early overt phases of SS disease at the cellular level.

Salivary Biomarkers and Their Application in the Diagnosis and Monitoring of the Most Common Oral Pathologies.

Saliva is a highly versatile biological fluid that is easy to gather in a non-invasive manner-and the results of its analysis complement clinical and histopathological findings in the diagnosis of multiple diseases. The objective of this review was to offer an update on the contribution of salivary biomarkers to the diagnosis and prognosis of diseases of the oral cavity, including oral lichen planus, periodontitis, Sjögren's syndrome, oral leukoplakia, peri-implantitis, and medication-related osteonecrosis of the jaw. Salivary biomarkers such as interleukins, growth factors, enzymes, and other biomolecules have proven useful in the diagnosis and follow-up of these diseases, facilitating the early evaluation of malignization risk and the monitoring of disease progression and response to treatment. However, further studies are required to identify new biomarkers and verify their reported role in the diagnosis and/or prognosis of oral diseases.

TREX1 variants in Sjogren's syndrome related lymphomagenesis.

Genetic variants of the three-prime repair exonuclease 1 (TREX1) -an exonuclease involved in DNA repair and degradation- have been previously found to increase susceptibility to Aicardi Goutieres syndrome, familial chilblain lupus and systemic lupus erythematosus. We aimed to explore whether TREX1 common variants could influence the risk of primary Sjogren's syndrome (SS) and SS-related lymphoma. Three single nucleotide polymorphisms (SNPs) of the TREX1 gene (rs11797, rs3135941 and rs3135945) were evaluated in 229 SS, 89 SS-lymphoma (70 SS-MALT and 19 SS non-MALT) and 240 healthy controls by PCR-based assays. In available 52 peripheral blood and 26 minor salivary gland tissues from our SS cohort, mRNA expression of type I interferon (IFN) related genes and TREX1 was determined by real-time PCR. Significantly decreased prevalence of rs11797 A minor allele was detected in SS patients complicated by non-MALT lymphoma compared to controls (ΟR [95% CI]: 0.4 [0.2-0.9], p-value: 0.02). SS patients carrying the rs11797 AA genotype had increased type I IFN related gene mRNA expression in minor salivary gland tissues. These data support genetically related dampened type I IFN production as an additional mechanism for SS-related lymphomagenesis.

MMP-9 Inhibition Suppresses Interferon-γ-Induced CXCL10 Production in Human Salivary Gland Ductal Cells.

Gene expression profiling of lip salivary gland (LSG) has shown that C-X-C motif chemokine 10 (CXCL10) and matrix metalloproteinase 9 (MMP9) expression is upregulated in primary Sjögren's syndrome (pSS) patients. Although CXCL10 and MMP-9 are both associated with pSS pathogenesis, the potential relationship between these two factors has not been investigated. In this study, we used LSG sections from pSS patients and human salivary gland cell lines to investigate the relationship between CXCL10 and MMP-9. Immunofluorescence analyses revealed that CXCL10 and MMP-9 were co-expressed in the LSG of pSS patients, particularly in expanded ductal cells. Furthermore, RT-qPCR analyses on human salivary gland ductal NS-SV-DC cells confirmed that CXCL10 expression was induced by interferon (IFN)-γ, whereas that of MMP9 was stimulated by IFN-α, tumor necrosis factor-α, and interleukin-1ß. Remarkably, MMP-9 inhibition in IFN-γ-stimulated NS-SV-DC cells significantly decreased CXCL10 mRNA and secreted protein levels. Further analyses established that MMP-9 inhibition in IFN-γ-stimulated NS-SV-DC cells decreased STAT1 phosphorylation and hence suppressed IFN-γ signaling. Collectively, these results suggest that in addition to its reported role in the destruction of acinar structures, MMP-9 is involved in the IFN-γ-induced production of CXCL10 in pSS lesions. We believe that our findings open the door to the development of novel treatments for pSS, based on the modulation of MMP-9 activity.

Plasma α-L-fucosidase-1 in patients with Sjögren's syndrome and other rheumatic disorders.

BACKGROUND: Human α-fucosidase (EC 3.2.1.51) is a hydrolase the importance of which has been increasing in the latest years. However, data about its plasma level in children with autoimmune disorders, particularly Sjögren's syndrome (SS), are lacking. In this study, the plasma activity of L-α-fucosidase-1 (α-L-FUCA-1) was assayed in hospitalized children and adults and its association with SS and other rheumatic disorders further evaluated. METHODS: In total 73 Hungarian hospitalized patients, 32 children (2.5-10 years) and 41 adults (32-68 years), were enrolled in the study and underwent plasma assay of α-L-FUCA1 activity. Linear regression, Durbin-Watson (DW), and Pearson tests were evaluated to investigate the relationship between α-L-FUCA-1 plasma levels and autoimmune manifestations. RESULTS: α-L-FUCA-1 correlated with SS both in children (2-sided t test, P = 0.0023) and in adults (2-sided t test, P = 0.00035). Linear regressions showed that in other rheumatic disorders, α-L-FUCA1 did not show any differential distribution related to the particular pathology (r = 0.2042, P = 0.1531, DW test = 2.2139 positive), while this trend was radically opposite for patients with SS (r = 0.1462, P = 0.0032, DW test = 1.3664, negative). CONCLUSIONS: Alterations in plasma level of α-L-FUCA-1 were significantly associated with SS. This preliminary result should encourage further research on α-L-FUCA-1 as a possible differential serological marker of SS.

Differential effects of specific cathepsin S inhibition in biocompartments from patients with primary Sjögren syndrome.

OBJECTIVE: Primary Sjögren syndrome (pSS) is characterized by T and B cell infiltration of exocrine glands. The cysteine protease cathepsin S (CatS) is crucially involved in MHCII processing and T cell stimulation, and elevated levels have been found in patients with RA, psoriasis and pSS. However, little is known about the functional characteristics and mechanisms of SS-A- and SS-B-specific T cells in pSS patients. We herein investigated the inhibition of CatS activity in different biocompartments of pSS patients including antigen-specific T cell responses. METHODS: Ex vivo CatS activity was assessed in tears, plasma and saliva of 15 pSS patients and 13 healthy controls (HC) and in the presence or absence of the specific CatS inhibitor RO5459072. In addition, antigen (SS-A (60kD), SS-B, influenza H3N2, tetanus toxoid and SEB)-specific T cell responses were examined using ex vivo IFN-γ/IL-17 Dual ELISPOT and Bromdesoxyuridin (BrdU) proliferation assays in the presence or absence of RO5459072. Supernatants were analysed for IL-1ß, IL-6, IL-10, TNF-α, IL-21, IL-22 and IL-23, using conventional ELISA. RESULTS: CatS activity was significantly elevated in tear fluid, but not other biocompartments, was inversely associated with exocrinic function in pSS patients and could significantly be suppressed by RO5459072. Moreover, CatS inhibition by RO5459072 led to strong and dose-dependent suppression of SS-A/SS-B-specific T cell effector functions and cytokine secretion by CD14+ monocytes. However, RO5459072 was incapable of suppressing SS-A/SS-B-induced secretion of cytokines in CD14+ monocytes when T cells were absent, confirming a CatS/MHCII-mediated mechanism of suppression. CONCLUSION: CatS activity in tear fluid seems to be a relevant biomarker for pSS disease activity. Conversely, CatS inhibition diminishes T cell and associated monokine responses towards relevant autoantigens in pSS. Thus, CatS inhibition may represent a promising novel treatment strategy in pSS.

Phosphatidylinositol 3-kinase delta pathway: a novel therapeutic target for Sjögren's syndrome.

BACKGROUND: The phosphatidylinositol 3-kinase delta isoform (PI3Kδ) belongs to an intracellular lipid kinase family that regulate lymphocyte metabolism, survival, proliferation, apoptosis and migration and has been successfully targeted in B-cell malignancies. Primary Sjögren's syndrome (pSS) is a chronic immune-mediated inflammatory disease characterised by exocrine gland lymphocytic infiltration and B-cell hyperactivation which results in systemic manifestations, autoantibody production and loss of glandular function. Given the central role of B cells in pSS pathogenesis, we investigated PI3Kδ pathway activation in pSS and the functional consequences of blocking PI3Kδ in a murine model of focal sialoadenitis that mimics some features of pSS. METHODS AND RESULTS: Target validation assays showed significant expression of phosphorylated ribosomal protein S6 (pS6), a downstream mediator of the phosphatidylinositol 3-kinase delta (PI3Kδ) pathway, within pSS salivary glands. pS6 distribution was found to co-localise with T/B cell markers within pSS aggregates and the CD138+ plasma cells infiltrating the glands. In vivo blockade of PI3Kδ activity with seletalisib, a PI3Kδ-selective inhibitor, in a murine model of focal sialoadenitis decreased accumulation of lymphocytes and plasma cells within the glands of treated mice in the prophylactic and therapeutic regimes. Additionally, production of lymphoid chemokines and cytokines associated with ectopic lymphoneogenesis and, remarkably, saliva flow and autoantibody production, were significantly affected by treatment with seletalisib. CONCLUSION: These data demonstrate activation of PI3Kδ pathway within the glands of patients with pSS and its contribution to disease pathogenesis in a model of disease, supporting the exploration of the therapeutic potential of PI3Kδ pathway inhibition in this condition.

α-enolase is an antigenic target in primary Sjögren's syndrome.

OBJECTIVES: Although anti-cyclic citrullinated peptides antibodies are specific markers for rheumatoid arthritis (RA), they might be present in other diseases. Our aim was to assess the native or citrullinated antigens recognised by patients with primary Sjögren's syndrome (pSS) and to evaluate their association with clinical and serological features. METHODS: In an initial screening, we assessed the serum reactivity of 12 patients with pSS against native or in vitro citrullinated antigens of HEp-2 cells by immunoblotting. We identified a 47kDa band, which was preferentially recognised and corresponded to α-enolase. Thus, levels of IgA and IgG anti-native and citrullinated α-enolase antibodies were measured in 50 pSS patients, 20 RA patients and 20 healthy subjects (HS) by ELISA. RESULTS: We identified α-enolase as a predominant antigen recognised in pSS. These patients had higher levels of anti-citrullinated α-enolase IgG antibodies compared with RA or HS (p=0.003 and p<0.0001, respectively). Furthermore, there was an increase of IgG anti-citrullinated α-enolase vs IgG anti-non-citrullinated α-enolase antibodies in pSS patients (p=0.001), by contrast no difference was found in RA. The presence of IgA and IgG anti-non-citrullinated and anti-citrullinated α-enolase antibodies were not associated with any clinical manifestation whatsoever, including non-erosive arthritis among pSS, but an association of IgA anti-citrullinated α-enolase with anti-Ro/SSA antibodies was found. CONCLUSIONS: We characterised α-enolase as a dominant antigen in lysates of HEp- 2 cells in pSS. Nevertheless, their precise role in pSS remains to be elucidated.

Proprotein convertase enzyme FURIN is upregulated in primary Sjögren's syndrome.

OBJECTIVES: The proprotein convertase enzyme FURIN is a critical regulator of the anti-inflammatory TGFß-1 cytokine and peripheral immune tolerance. In T cells, FURIN is co-regulated with IFN-γ and thus highly expressed in T helper 1 type cells. Previous studies have demonstrated that FURIN is upregulated in inflammatory conditions, including atherosclerosis, rheumatoid arthritis and systemic lupus erythematosus. Here, we evaluated the levels of FURIN in the plasma and peripheral blood mononuclear cells (PBMCs) of patients with primary Sjögren's syndrome (pSS) and in healthy controls. METHODS: FURIN plasma levels were determined by ELISA, and the mRNA expression in PBMCs was quantitated using qPCR. FURIN levels in the plasma were correlated with the clinical and demographic characteristics of the patients. RESULTS: FURIN was found to be significantly upregulated at both the protein and mRNA level in pSS patients compared to healthy controls. In pSS patients, high FURIN protein levels were significantly associated with elevated IFN-γ levels in the plasma as well as a longer duration of sicca symptoms in the eyes. pSS patients with high FURIN levels in their plasma showed a trend towards lower levels of serum beta-2 microglobulin, ESR and a lower systemic disease activity index ESSDAI. CONCLUSIONS: The proprotein convertase FURIN is significantly upregulated in pSS. Elevated FURIN levels associate with high levels of the Th1 type cytokine IFN-γ and long duration of dry eye symptoms. Patients with high FURIN levels show signs of lower disease activity suggesting that FURIN might have a protective role in pSS.

Activation of MMP-9 activity by acrolein in saliva from patients with primary Sjögren's syndrome and its mechanism.

We have recently reported that the altered recognition patterns of immunoglobulins due to acrolein conjugation are at least partially responsible for autoimmune diseases in patients with primary Sjögren's syndrome (pSS). In the current study, it was found that the specific activity (activity/ng protein) of metalloproteinase-9 (MMP-9) in saliva was elevated about 2.4-fold in pSS patients. Accordingly, it was examined whether MMP-9 is activated by acrolein. It was found that the MMP-9 with 92kDa molecular weight was activated by acrolein. Under the conditions studied, Cys99, located in the propeptide, was conjugated with acrolein together with Cys230, 244, 302, 314, 329, 347, 361, 373, 388 and 516, which are located in fibronectin repeats and glycosyl domains, but not on the active site of MMP-9. In addition, 82 and 68kDa constructs of MMP-9s, lacking the NH2-terminal domain that contains Cys99, were not activated by acrolein. The results suggest that acrolein conjugation at Cys99 caused the active site of MMP-9 to be exposed. Activation of MMP-9 by acrolein was inhibited by cysteine, and slightly by lysine, because these amino acids inhibited acrolein conjugation with MMP-9. Conversely, MMP-9 activity in the presence of 50µM acrolein was enhanced by 100µM histidine. This was due to the inhibition of acrolein conjugation with His405 and 411 located at the Zn2+ binding site of MMP-9. These results suggest that activation of 92kDa MMP-9 by acrolein is involved in tissue damage in pSS patients and is regulated by cysteine and histidine, and slightly by lysine. Activated 82 and 68kDa MMP-9s were not detected in saliva of pSS patients by Western blotting.

Enhanced Bruton's Tyrosine Kinase Activity in Peripheral Blood B Lymphocytes From Patients With Autoimmune Disease.

OBJECTIVE: Bruton's tyrosine kinase (BTK) transmits crucial survival signals from the B cell receptor (BCR) in B cells. Pharmacologic BTK inhibition effectively diminishes disease symptoms in mouse models of autoimmunity; conversely, transgenic BTK overexpression induces systemic autoimmunity in mice. We undertook this study to investigate BTK expression and activity in human B cells in the context of autoimmune disease. METHODS: Using intracellular flow cytometry, we quantified BTK expression and phosphorylation in subsets of peripheral blood B cells from 30 patients with rheumatoid arthritis (RA), 26 patients with primary Sjögren's syndrome (SS), and matched healthy controls. RESULTS: In circulating B cells, BTK protein expression levels correlated with BTK phosphorylation. BTK expression was up-regulated upon BCR stimulation in vitro and was significantly higher in CD27+ memory B cells than in CD27-IgD+ naive B cells. Importantly, BTK protein and phospho-BTK were significantly increased in B cells from anti-citrullinated protein antibody (ACPA)-positive RA patients but not in B cells from ACPA-negative RA patients. BTK was increased both in naive B cells and in memory B cells and correlated with frequencies of circulating CCR6+ Th17 cells. Likewise, BTK protein was increased in B cells from a major fraction of patients with primary SS and correlated with serum rheumatoid factor levels and parotid gland T cell infiltration. Interestingly, targeting T cell activation in patients with primary SS using the CTLA-4Ig fusion protein abatacept restored BTK protein expression in B cells to normal levels. CONCLUSION: These data indicate that autoimmune disease in humans is characterized by enhanced BTK activity, which is linked not only to autoantibody formation but also to T cell activity.

Imbalanced Rab3D versus Rab27 increases cathepsin S secretion from lacrimal acini in a mouse model of Sjögren's Syndrome.

The mechanism responsible for the altered spectrum of tear proteins secreted by lacrimal gland acinar cells (LGAC) in patients with Sjögren's Syndrome (SS) remains unknown. We have previously identified increased cathepsin S (CTSS) activity as a unique characteristic of tears of patients with SS. Here, we investigated the role of Rab3D, Rab27a, and Rab27b proteins in the enhanced release of CTSS from LGAC. Similar to patients with SS and to the male nonobese diabetic (NOD) mouse model of SS, CTSS activity was elevated in tears of mice lacking Rab3D. Findings of lower gene expression and altered localization of Rab3D in NOD LGAC reinforce a role for Rab3D in suppressing excess CTSS release under physiological conditions. However, CTSS activity was significantly reduced in tears of mice lacking Rab27 isoforms. The reliance of CTSS secretion on Rab27 activity was supported by in vitro findings that newly synthesized CTSS was detected in and secreted from Rab27-enriched secretory vesicles and that expression of dominant negative Rab27b reduced carbachol-stimulated secretion of CTSS in cultured LGAC. High-resolution 3D-structured illumination microscopy revealed microdomains of Rab3D and Rab27 isoforms on the same secretory vesicles but present in different proportions on different vesicles, suggesting that changes in their relative association with secretory vesicles may tailor the vesicle contents. We propose that a loss of Rab3D from secretory vesicles, leading to disproportionate Rab27-to-Rab3D activity, may contribute to the enhanced release of CTSS in tears of patients with SS.

Role of Matrix Metalloproteinases 2 and 9 in Lacrimal Gland Disease in Animal Models of Sjögren's Syndrome.

PURPOSE: Chronic inflammation of the lacrimal gland results in changes in the composition of the extracellular matrix (ECM), which is believed to compromise tissue repair. We hypothesized that increased production/activity of matrix metalloproteinases (MMPs), especially MMP-2 and -9, in inflamed lacrimal glands modifies the ECM environment, therefore disrupting tissue repair. METHODS: The lacrimal glands from female MRL/lpr and male NOD mice along with their respective control strains were harvested and divided into three pieces and processed for histology, immunohistochemistry, zymography, Western blotting, and RNA analyses. In another study, MRL/lpr mice were treated for 5 weeks with a selective MMP2/9 inhibitor peptide or a control peptide. At the end of treatment, the lacrimal glands were excised and the tissue was processed as described above. RESULTS: There was a 2.5- and 2.7-fold increase in MMP2 gene expression levels in MRL/lpr and NOD mice, respectively. Matrix metalloproteinase 2 and 9 enzymatic activities and protein expression levels were significantly upregulated in the lacrimal glands of MRL/lpr and NOD mice compared to controls. Treatment with the MMP2/9 inhibitor resulted in decreased activity of MMP-2 and -9 both in vitro and in vivo. Importantly, MMP2/9 inhibitor treatment of MRL/lpr mice improved aqueous tear production and resulted in reduced number and size of lymphocytic foci in diseased lacrimal glands. CONCLUSIONS: We conclude that MMP2/9 expression and activity are elevated in lacrimal glands of two murine models of Sjögren's syndrome, suggesting that manipulation of MMP2/9 activity might be a potential therapeutic target in chronically inflamed lacrimal glands.

Action of anti-M3muscarinic acetylcholine receptor IgG of primary Sjögren's syndrome on the enzymatic antioxidant system in rat submandibular gland.

BACKGROUND: We demonstrate that serum immunoglobulin G (IgG) directed against glandular M3 muscarinic acetylcholine receptors (M3mAChR) and pilocarpine triggers the increment of superoxide dismutase (SOD) and catalase (CAT) and the production of nitric oxide (NO) and prostaglandin E2(PGE2). METHODS: Enzyme-linked immunosorbent assay (ELISA) was performed in the presence of the human M2mAChR synthetic peptide as antigen to detect in serum of pSS patients the autoantibodies. Further, SOD and CAT specific activity and NO were determined chemically in the presence of anti-M3mAChR IgG and pilocarpine. The level of PGE2generation in the presence of autoantibody and pilocarpine was determined by ELISA. RESULTS: An association between anti-M2mAChR autoantibodies and pilocarpine given the increment of the specific activity of SOD and CAT in the serum of pSS patients and in the rat submandibular gland was observed. As a result of this action, M3synthetic peptide and atropine abrogated the stimulatory action. The L-type calcium channel, calcium/calmodulin complex and COX-2 inhibitors selectively blocked the increment of the specific activity of SOD and CAT in the rat submandibular gland. An increased production of NO and PGE2by the cholinergic autoantibody and pilocarpine was also detected. CONCLUSION: On the basis of these results, the increment of the specific activity of SOD and CAT in pSS patients as compared to control healthy individuals may be seen as a defensive reaction to the increment of the amount of ROS, which becoming uncontrollable, leads to irreversible cellular and tissue damage.

Umbilical cord mesenchymal stem cells inhibit the differentiation of circulating T follicular helper cells in patients with primary Sjögren's syndrome through the secretion of indoleamine 2,3-dioxygenase.

OBJECTIVE: The aim of this study was to investigate the effect of umbilical cord mesenchymal stem cells (UC-MSCs) on circulating T follicular helper (cTfh) cells in primary SS (pSS) patients. METHODS: The percentage of CXCR5(+)PD-1(+)CD4(+) T cells in peripheral blood mononuclear cells (PBMCs) was analysed by flow cytometry. PBMCs were co-cultured with UC-MSCs by cell-to-cell contact or in a trans-well system. Naive CD4(+) T cells were isolated from PBMCs and then co-cultured with UC-MSCs under Tfh cell-polarizing conditions. The percentage of CXCR5(+)PD-1(+)CD4(+) T cells, carboxyfluorescein succinimidyl ester (CFSE) fluorescence intensity and annexin V were determined by flow cytometric analysis. Real-time PCR and Luminex cytokine assay were performed to detect mRNA expression and supernatant protein levels. The activity of indoleamine 2,3-dioxygenase (IDO) was measured by HPLC. RESULTS: Increased frequency of cTfh cells was found in pSS patients and was positively correlated with serum anti-La/SSB levels and the European League Against Rheumatism SS Disease Activity Index score. In vitro, UC-MSCs suppressed the differentiation and proliferation of cTfh cells. Real-time PCR analysis showed significantly higher IDO mRNA expression on UC-MSCs when co-cultured with naive CD4(+) T cells under Tfh cell-polarizing conditions in pSS patients. However, IDO mRNA expression on UC-MSCs was only a little higher when UC-MSCs were co-cultured with naive CD4(+) T cells in a trans-well system. In addition, HPLC showed increased IDO enzymic activity in the supernatant of UC-MSCs co-cultured with naive CD4(+) T cells under Tfh cell-polarizing conditions in pSS. The addition of the IDO inhibitor 1-MT partly reversed the suppressive effect of UC-MSCs on the differentiation of cTfh cells. CONCLUSION: These results suggest an inhibitory effect of UC-MSCs on the differentiation of cTfh cells via the secretion of IDO, and soluble factors secreted by activated CD4(+) T cells might contribute to IDO secretion by UC-MSCs.

Aromatase controls Sjögren syndrome-like lesions through monocyte chemotactic protein-1 in target organ and adipose tissue-associated macrophages.

Several autoimmune diseases are known to develop in postmenopausal women. However, the mechanism by which estrogen deficiency influences autoimmunity is unknown. Aromatase is an enzyme that converts androgens to estrogens. Herein, we used female aromatase gene knockout (ArKO) mice as a model of estrogen deficiency to investigate the molecular mechanism that underlies the onset and development of autoimmunity. Histological analyses showed that inflammatory lesions in the lacrimal and salivary glands of ArKO mice increased with age. Adoptive transfer of spleen cells or bone marrow cells from ArKO mice into recombination activating gene 2 knockout mice failed to induce the autoimmune lesions. Expression of mRNA encoding proinflammatory cytokines and monocyte chemotactic protein-1 increased in white adipose tissue of ArKO mice and was significantly higher than that in wild-type mice. Moreover, an increased number of inflammatory M1 macrophages was observed in white adipose tissue of ArKO mice. A significantly increased monocyte chemotactic protein-1 mRNA expression of the salivary gland tissue in ArKO was found together with adiposity. Furthermore, the autoimmune lesions in a murine model of Sjögren syndrome were exacerbated by administration of an aromatase inhibitor. These results suggest that aromatase may play a key role in the pathogenesis of Sjögren syndrome-like lesions by controlling the target organ and adipose tissue-associated macrophage.

Matrix metalloproteinase 9 and transglutaminase 2 expression at the ocular surface in patients with different forms of dry eye disease.

OBJECTIVE: To evaluate the expression of matrix metalloproteinase 9 (MMP9) and transglutaminase 2 (TG2) in different forms of dry eye. DESIGN: Case control study. PARTICIPANTS: Seventy-five female subjects divided into 3 groups: group 1, 15 healthy controls; group 2, 30 subjects with Sjögren syndrome (SS); and group 3, 30 subjects with Meibomian gland dysfunction (MGD). METHODS: A clinical assessment was carried out and impression cytologic specimens were processed for immunoperoxidase staining for MMP9 and TG2 and real-time polymerase chain reaction analyses were carried out for MMP9, TG2, interleukin-6, interferon-γ, B-cell lymphoma 2, and caspase 3. To study MMP9 and TG2 expression after anti-inflammatory treatment, patients were divided into 2 subgroups, one treated with saline and the other treated with saline plus topical corticosteroid eye drops (0.5% loteprednol etabonate) 4 times daily for 15 days. For statistical analysis, Student t test, Mann-Whitney U test, and Spearman's correlation coefficient were used as appropriate. MAIN OUTCOME MEASURES: Conjunctival expression of MMP9 and TG2. RESULTS: MMP9 and TG2 expression were higher in both patient groups than in controls (P < 0.0001). Group 2 patients showed higher expression than group 3 (P < 0.0001). The Spearman's correlation coefficient showed in group 2 a positive correlation between MMP9 and TG2 expression (ρ = 0.437; P = 0.01), but no correlation in group 3 (ρ = 0.143; P = 0.45). Corticosteroid treatment significantly reduced MMP9 and TG2 expression in both groups, ameliorating symptoms and signs. A much higher percentage reduction was observed in SS. CONCLUSIONS: The pathogenic mechanisms of the 2 forms of dry eye give an account for the different MMP9 and TG2 expressions in the 2 groups of patients. The higher expression in SS is determined by the direct autoimmune insult to the ocular surface epithelia, whereas in MGD patients, with an epithelial damage due to an unbalanced tear secretion, the molecules expression is significantly lower, although higher than in controls. The corticosteroid treatment induced a reduction of both molecules, although higher in SS than in MGD, because of its direct inhibitory effect on inflammation.