Ductal epithelial expression of Ro52 correlates with inflammation in salivary glands of patients with primary Sjögren's syndrome

Potential Novel Tissue Biomarkers in Salivary Glands of Patients with Sjogren's Syndrome

Background/Objectives: Primary Sjogren's syndrome (pSS) is an autoimmune disease caused by chronic inflammation of the exocrine glands. We aimed to determine the immunohistochemical parameters that may help in the diagnosis of pSS and to determine histopathological markers for the early diagnosis of patients. Methods: Hematoxylin-eosin-stained preparations of salivary gland tissue samples of a control group consisting of 9 healthy patients and 12 patients diagnosed with non-specific chronic sialadenitis (NSCS) and a study group consisting of 39 patients diagnosed with pSS were evaluated. SSA/Ro (TRIM21), SSB/la, BAFF, enolase (ENO1), and MMP-9 antibodies were applied to the samples to assess the presence of staining in the ductal, acini, and inflammation regions. Results: In our study, mild staining with the SSA/Ro (TRIM21) antibody was observed in the ductal areas of all pSS cases, while no staining was detected in the healthy and NSCS cases (p < 0.01). Additionally, stronger staining was identified in the ductal and inflammatory areas of the pSS cases with BAFF compared to the control group. The staining for the ENO1 antibody was higher and more intense in the NSCS and pSS cases compared to those with normal salivary glands, and this difference was found to be statistically significant (p < 0.01). While mild staining was detected in the ductal areas with MMP-9 antibody in most of the NSCS and pSS cases, it was detected in 11% of the healthy cases. Conclusions: Our study suggests that SSA/Ro (TRIM21), ENO1, MMP9, and BAFF can be used to confirm the diagnosis in cases of suspicion.

Roles of TRIM21/Ro52 in connective tissue disease-associated interstitial lung diseases

Multiple factors contribute to the development of connective tissue diseases (CTD), often alongside a range of interstitial lung diseases (ILD), including Sjögren's syndrome-associated ILD, systemic sclerosis-associated ILD, systemic lupus erythematosus-associated ILD, idiopathic inflammatory myositis-associated ILD. TRIM21(or Ro52), an E3 ubiquitin ligase, plays a vital role in managing innate and adaptive immunity, and maintaining cellular homeostasis, and is a focal target for autoantibodies in various rheumatic autoimmune diseases. However, the effectiveness of anti-TRIM21 antibodies in diagnosing CTD remains a matter of debate because of their non-specific nature. Recent studies indicate that TRIM21 and its autoantibody are involved in the pathogenesis of CTD-ILD and play an important role in diagnosis and prognosis. In this review, we focus on the contribution of TRIM21 in the pathogenesis of CTD-ILD, as well as the potential diagnostic value of its autoantibodies in different types of CTD-ILD for disease progression and potential as a novel therapeutic target.

Ro52/TRIM21 - From host defense to autoimmunity

Ro52 (TRIM21) belongs to the ubiquitin ligase family. This protein plays a crucial role in many immunological processes, including antibody-dependent intracellular neutralization, synergy with the complement system, antiviral response, death mediation, oxidative stress response, and protein ubiquitination. Abnormal expression of TRIM21 can break immunological tolerance and lead to the production of autoantibodies against TRIM21. Antibodies against TRIM21 are detected in various autoimmune diseases, including Sjögren's syndrome (SS), systemic lupus erythematosus (SLE), or myositis. However, anti-TRIM21 presence is not limited to autoimmune connective tissue disorders. It was observed in patients with malignancies, various cancerous processes, infectious diseases, and idiopathic interstitial pneumonia. The occurrence of TRIM21 autoantibodies is also associated with clinical features, such as the prevalence of interstitial lung diseases and cardiac or haematological involvement in connective tissue disorders. The purpose of this review was to summarize current knowledge of the immunological functions of TRIM21 and analyze the clinical implications of anti-TRIM21 antibodies in the disease course.

The Toll-like Receptor 7-Mediated Ro52 Antigen-Presenting Pathway in the Salivary Gland Epithelial Cells of Sjögren's Syndrome

OBJECTIVE

To investigate whether stimulation with toll-like receptor (TLR) 7 leads to pathways that proceed to tripartite motif-containing protein 21 (TRIM21) or Ro52/SS-A antigen presentation through major histocompatibility complex (MHC) class I in salivary gland epithelial cells (SGECs) from Sjögren's syndrome (SS) patients.

DESIGN AND METHODS

Cultured SGECs from SS patients were stimulated with TLR7 agonist, loxoribine, and interferon-β. Cell lysates immunoprecipitated by anti-MHC class I antibody were analyzed by Western blotting. The immunofluorescence of salivary gland tissue from SS and non-SS subjects and cultured TLR7-stimulated SGECs was examined.

RESULTS

Significantly increased MHC class I expression was observed in SS patients' ducts versus non-SS ducts; no significant difference was detected for ubiquitin. Upregulated MHC class I in the cell membrane and cytoplasm and augmented Ro52 expression were observed in SGECs stimulated with TLR7. The formation of peptide-loading complex (PLC), including tapasin, calreticulin, transporter associated with antigen processing 1, and endoplasmic reticulum-resident protein 57 in labial salivary glands (LSGs) from SS patients, was dominantly observed and colocalized with MHC class I, which was confirmed in TLR7-stimulated SGEC samples.

CONCLUSION

These findings suggest that the TLR7 stimulation of SS patients' SGECs advances the process toward the antigen presentation of TRIM21/Ro52-SS-A via MHC class I.

Multiple fibrotic lung nodules in a patient with primary Sjögren's syndrome

Evaluation of bilateral lung nodules noted on imaging poses a diagnostic challenge to clinicians as it can have many differentials from benign to malignant causes. It becomes especially critical to identify them right when there are underlying autoimmune conditions and risk factors for infection. However, a thorough investigation can lead to the recognition of rare associations as described below. We present here a 57-year-old woman who was admitted to the hospital with shortness of breath. Imaging with a computed tomography (CT) scan showed that she had 8 bilateral cystic pulmonary nodules with focal areas of ground-glass opacity and mediastinal lymphadenopathy. Fibrobronchoscopy and histopathological studies were done on the right middle lobe lung nodule demonstrated that the lung nodule was fibrotic with reactive inflammation but showed no malignant cells. Upon further detailed history and chart review, it was noted that the patient had a history of dry eyes leading to an autoimmune workup showing positive antinuclear antibodies (ANA), anti-Ro, and anti-La antibodies with no follow-up since then. This lead to the suspicion that these nodules could be related to underlying Sjögren's syndrome. Initial inpatient management with intravenous steroids showed significant improvement in her symptomatology. Hence, we present this rare association of lung nodules with Sjögren's syndrome and its management for awareness of this condition.

Salivary gland ultrasound is associated with the presence of autoantibodies in patients with Sjögren's syndrome: A Danish single-centre study

OBJECTIVES

To investigate whether ultrasound findings of major salivary glands are correlated with serological markers, autoantibodies, patient- or doctor-reported disease activity in a Danish cohort of patients with primary Sjögren's Syndrome (pSS).

METHODS

In all, 49 patients at Odense University Hospital with pSS diagnosed according to the 2002 American-European Consensus Group (AECG) classification criteria were included. Patients were characterized using the EULAR Sjögren's Syndrome Disease Activity Index (ESSDAI, score of systemic complications) and EULAR Sjögren's Syndrome Patient Reported Index (ESSPRI), serologic markers, Schirmer's test and salivary test. Salivary gland ultrasound (SGUS) was performed of the submandibular and parotid glands and scored according to the Outcome Measures in Rheumatoid Arthritis Clinical Trials (OMERACT) semi-quantitative scoring system.

RESULTS

More patients with abnormal SGUS had antinuclear antibodies (ANA) (p = 0.002), anti-Ro52 (p = 0.001), anti-Ro60 (p<0.001), anti-La (p<0.001) and IgM-RF (p<0.001). Titers for ANA (p = 0.02) and anti-Ro52 (p = 0.03) were higher in patients with abnormal SGUS. Twenty-three of the pSS patients had no pathological findings on SGUS. There was no correlation between SGUS severity and ESSDAI- or ESSPRI-scores.

CONCLUSIONS

Abnormal SGUS findings are associated with autoantibodies of high specificity for pSS but not with ESSDAI, ESSPRI or inflammatory markers.

Circulating Th2 cell reduction and Th1/Th2 imbalance are correlated with primary Sjogren's syndrome-associated interstitial lung disease

OBJECTIVE

Primary Sjogren's syndrome (pSS) is a heterogeneous chronic autoimmune disorder characterized by lymphocyte infiltration of the exocrine glands and the involvement and dysfunction of multiple organs and tissues. Interstitial lung disease (ILD) is the most common type of respiratory system damage. This study ascertained the factors related to ILD in patients with pSS (pSS-ILD), such as altered levels of circulating lymphocyte subtypes.

METHODS

Eighty healthy controls and 142 patients diagnosed with pSS were included. The pSS patients were classified into groups with pSS-ILD or pSS without ILD (pSS-non-ILD). Baseline clinical and laboratory data were collected for all subjects, including the levels of lymphocytes measured by modified flow cytometry.

RESULTS

The pSS-ILD patients were older, had higher ESSDAI scores, had higher positivity rates for anti-SSB and anti-Ro52 antibodies, and had more frequent symptoms of respiratory system involvement than pSS-non-ILD patients. pSS-ILD patients had the lowest Th2 cell counts among the three groups. Although the absolute numbers of Treg and NK cells were lower in pSS patients with and without ILD than in the healthy controls, there was no significant difference between the two pSS groups. The Th1/Th2 ratio was significantly higher in patients with ILD than in patients without ILD. Further analysis showed that older age (OR=1.084), lower Th2 count (OR=0.947), higher Th1/Th2 ratio (OR=1.021), and positivity for anti-SSB (OR=3.620) and anti-Ro52 (OR=5.184) antibodies were associated with the occurrence of ILD in patients with pSS.

CONCLUSION

Decreased circulating Th2 cells and an elevated Th1/Th2 ratio may be the immunological mechanism underlying the development of ILD in pSS patients.

An updated review of anti-Ro52 (TRIM21) antibodies impact in connective tissue diseases clinical management

Anti-Ro52 (or anti-TRIM21) antibodies are part of the family of anti-Ro/SSA antibodies, historically markers of Sjögren syndrome and systemic lupus erythematosus. Anti-Ro52 antibodies represent one the most frequently encountered autoantibodies in patients with connective tissue disease (primary Sjögren syndrome, systemic lupus erythematosus, systemic sclerosis and idiopathic inflammatory myopathies). Because of their lack of specificity and detection in patients with non-autoimmune disorders, the usefulness of anti-Ro52 testing in connective tissue diseases is still matter of debate among clinicians and immunologists. Autoantibodies are mainly diagnostic markers for autoimmune diseases but some of them can also be directly involved in the generation of tissue damage. Over the past decade several authors reported associations of anti-Ro52 antibodies with some clinical features - especially interstitial lung disease - and survival in patients with connective tissue diseases. There is also a growing evidence of the role of anti-Ro52 antibodies in the pathogenesis of connective tissue diseases. In this review, we comprehensively discuss the clinical associations of anti-Ro52 antibodies in the different connective tissue diseases and the recent advances on their potential role in the inflammatory response.

TRIM21/Ro52 - Roles in Innate Immunity and Autoimmune Disease

TRIM21 (Ro52/SSA1) is an E3 ubiquitin ligase with key roles in immune host defence, signal transduction, and possibly cell cycle regulation. It is also an autoantibody target in Sjögren's syndrome, systemic lupus erythematosus, and other rheumatic autoimmune diseases. Here, we summarise the structure and function of this enzyme, its roles in innate immunity, adaptive immunity and cellular homeostasis, the pathogenesis of autoimmunity against TRIM21, and the potential impacts of autoantibodies to this intracellular protein.

Contributions of Major Cell Populations to Sjögren's Syndrome

Sjögren’s syndrome (SS) is a female dominated autoimmune disease characterized by lymphocytic infiltration into salivary and lacrimal glands and subsequent exocrine glandular dysfunction. SS also may exhibit a broad array of extraglandular manifestations including an elevated incidence of non-Hodgkin’s B cell lymphoma. The etiology of SS remains poorly understood, yet progress has been made in identifying progressive stages of disease using preclinical mouse models. The roles played by immune cell subtypes within these stages of disease are becoming increasingly well understood, though significant gaps in knowledge still remain. There is evidence for distinct involvement from both innate and adaptive immune cells, where cells of the innate immune system establish a proinflammatory environment characterized by a type I interferon (IFN) signature that facilitates propagation of the disease by further activating T and B cell subsets to generate autoantibodies and participate in glandular destruction. This review will discuss the evidence for participation in disease pathogenesis by various classes of immune cells and glandular epithelial cells based upon data from both preclinical mouse models and human patients. Further examination of the contributions of glandular and immune cell subtypes to SS will be necessary to identify additional therapeutic targets that may lead to better management of the disease.

Sex Effects on Gene Expression in Lacrimal Glands of Mouse Models of Sjögren Syndrome

Purpose

Sjögren syndrome is an autoimmune disease that occurs primarily in women, and is associated with lacrimal gland inflammation and aqueous-deficient dry eye. We hypothesize that sex-associated differences in lacrimal gland gene expression are very important in promoting lymphocyte accumulation in this tissue and contribute to the onset, progression, and/or severity of the inflammatory disease process. To test our hypothesis, we explored the nature and extent of sex-related differences in gene expression in autoimmune lacrimal glands.

Methods

Lacrimal glands were collected from age-matched, adult, male and female MRL/MpJ-Tnfrsf6^lpr (MRL/lpr) and nonobese diabetic/LtJ (NOD) mice. Glands were processed for the analysis of differentially expressed mRNAs by using CodeLink Bioarrays and Affymetrix GeneChips. Data were evaluated with bioinformatics and statistical software.

Results

Our results show that sex significantly influences the expression of thousands of genes in lacrimal glands of MRL/lpr and NOD mice. The immune nature of this glandular response is very dependent on the Sjögren syndrome model. Lacrimal glands of female, as compared with male, MRL/lpr mice contain a significant increase in the expression of genes related to inflammatory responses, antigen processing, and chemokine pathways. In contrast, it is the lacrimal tissue of NOD males, and not females, that presents with a significantly greater expression of immune-related genes.

Conclusions

These data support our hypothesis that sex-related differences in gene expression contribute to lacrimal gland disease in Sjögren syndrome. Our findings also suggest that factors in the lacrimal gland microenvironment are critically important in mediating these sex-associated immune effects.

Utility of paraneoplastic antigens as biomarkers for surveillance and prediction of recurrence in ovarian cancer

BACKGROUND

Ovarian cancer is frequently diagnosed at an advanced stage and 70% of patients experience recurrence months to years from initial diagnosis. The expression of paraneoplastic antigens can result in the occurrence of onconeural autoantibodies in ovarian cancer that may be associated with neurological disorders that are clinically manifested in patients before diagnosis of ovarian cancer. These paraneoplastic antigens can serve as excellent biomarkers not only for early detection but also for monitoring ovarian cancer recurrence.

OBJECTIVE

To assess the immunoreactivity of our previous 3 biomarkers along with 3 paraneoplastic antigens, HARS, Ro52 and CDR2 for the evaluation of their sensitivity in predicting recurrence before the clinical relapse of the ovarian cancer.

METHODS

Western blot immunoassays were performed to assess the immunoreactivity of 6 antigens with 21 recurrent ovarian cancer patients.

RESULTS

The results indicated that antibodies to HARS, Ro52, CDR2 and 5H6 antigens predicted ovarian cancer recurrence 5.03 months before the clinical or symptomatic relapse in 21 ovarian cancer patients with a sensitivity of 90.5% when CA125 levels were below the standard cutoff (35 U/ml).

CONCLUSION

Our study suggests that appearance of onconeural antibodies prior to the rise in CA125 during post treatment surveillance can be a useful diagnostic to predict ovarian cancer recurrence.

Update on Pathogenesis of Sjogren's Syndrome

Sjogren's syndrome is a common autoimmune disease that presents with sicca symptoms and extraglandular features. Sjogren's syndrome is presumably as common as RA; yet it is poorly understood, underdiagnosed and undertreated. From the usual identity as an autoimmune exocrinopathy to its most recent designate as an autoimmune epithelitis - the journey of SS is complex. We herein review some of the most important milestones that have shed light on different aspects of pathogenesis of this enigmatic disease. This includes role of salivary gland epithelial cells, and their interaction with cells of the innate and adaptive immune system. Non-immune factors acting in concert or in parallel with immune factors may also be important. The risk genes identified so far have only weak association, nevertheless advances in genetics have enhanced understanding of disease mechanisms. Role of epigenetic and environmental role factors is also being explored. SS has also some unique features such as congenital heart block and high incidence of lymphoma; disease mechanisms accounting for these manifestations are also reviewed.

Autoimmune manifestations in aged mice arise from early-life immune dysregulation

Autoantibodies can be present years to decades before the onset of disease manifestations in autoimmunity. This finding suggests that the initial autoimmune trigger involves a peripheral lymphoid component, which ultimately drives disease pathology in local tissues later in life. We show that Sjögren's syndrome manifestations that develop in aged NOD.H-2h4 mice were driven by and dependent on peripheral dysregulation that arose in early life. Specifically, elimination of spontaneous germinal centers in spleens of young NOD.H-2h4 mice by transient blockade of CD40 ligand (CD40L) or splenectomy abolished Sjögren's pathology of aged mice. Strikingly, a single injection of anti-CD40L at 4 weeks of age prevented tertiary follicle neogenesis and greatly blunted the formation of key autoantibodies implicated in glandular pathology, including anti-muscarinic receptor antibodies. Microarray profiling of the salivary gland characterized the expression pattern of genes that increased with disease progression and showed that early anti-CD40L greatly repressed B cell function while having a broader effect on multiple biological pathways, including interleukin-12 and interferon signaling. A single prophylactic treatment with anti-CD40L also inhibited the development of autoimmune thyroiditis and diabetes in NOD.H-2h4 and nonobese diabetic mice, respectively, supporting a key role for CD40L in the pathophysiology of several autoimmune models. These results strongly suggest that early peripheral immune dysregulation gives rise to autoimmune manifestations later in life, and for diseases predated by autoantibodies, early prophylactic intervention with biologics may prove efficacious.

Review of autoantigens in Sjögren's syndrome: an update

Primary Sjögren’s syndrome (pSS) is an autoimmune disease characterized by inflammation in exocrine glands, resulting in reduced secretion of tears and saliva, manifesting as xerophthalmia and xerostomia, respectively. It is commonly associated with Sjögren’s syndrome type A (Ro) and Sjögren’s syndrome type B (La) antigens. However, in most patients, the identity of the triggering antigen is not known. Factors such as genetics of histocompatibility, dysregulation of T-cells, B-cells and viral infections have been implicated. Several important studies on autoantigens in pSS have been published since a review in 2012, and the aim of this review is to provide an update on further peer-reviewed original articles in this field. Oxidative damage of Ro60 antigen may explain the epitope spreading during the immune activation in pSS. Immune-mediated destruction of the muscarinic receptor-3-expressing cells has been associated with a reduction in parasympathetic function, which could cause reduced secretory function of exocrine glands. Such a process also activates reactive oxidative species and antioxidants, which are linked to the triggering of inflammatory responses. Elevated levels of kallikrein, yet another antigen present in the lacrimal gland and other tissues, are similarly involved in triggering an autoimmune T-cell response against target glands. Studying additional antigens, the platelet-selectin and vasoactive intestinal peptides, in patients with pSS can help to elucidate the origin and process of autoimmunity, or even lead to potential biomarkers. In conclusion, the understanding of autoantigens has led to exciting major advances in the biology of pSS and may influence diagnosis and management of pSS in future.

Clinical associations of the positive anti Ro52 without Ro60 autoantibodies: undifferentiated connective tissue diseases

Aims

Autoantibodies targeting Ro52 and Ro60 antigens are historically reported as anti SSA/Ro. In general anti SSA/Ro results are either anti Ro52+Ro60+ or anti Ro52−Ro60+ antibodies. Anti Ro52 without anti Ro60 (Ro52+ Ro60−) antibodies are often not reported routinely. This study intends to review the potential significance of these autoantibodies in the management of connective tissue diseases.

Method

A retrospective survey of Ro52+Ro60− was carried out as part of the service evaluation of extractable nuclear antigen antibodies (ENA) reporting from the immunology laboratory, the NHS Greater Glasgow and Clyde (GGC), UK. The clinical documents and laboratory results of 97 patients with Ro52+Ro60− and 100 patients with Ro52+Ro60+ were reviewed.

Results

Seventy-one patients (73%) with anti Ro52+Ro60− antibodies have been diagnosed with autoimmune conditions including undifferentiated connective tissue diseases (n=14, 14%), systemic lupus erythematosus (n=10, 10%), Sjögren’s syndrome (n=10, 10%) and rheumatoid arthritis (n=13, 13%). Twenty-three patients (24%) with anti Ro52+Ro60− antibodies have no autoimmune features but were found to have significant clinical conditions including malignancies. In contrast, 87 patients (87%) with anti Ro52+Ro60+ antibodies have autoimmune conditions including Sjögren’s syndrome (n=34, 34%), systemic lupus erythematosus (SLE; n=23, 23%), undifferentiated connective tissue diseases (n=12, 12%) and rheumatoid arthritis (n=6, 6%).

Conclusion

Anti Ro52 without anti Ro60 (Ro52+Ro60−) antibodies should be reported. In the majority of patients these autoantibodies were associated with various autoimmune diseases. Anti Ro52+Ro60− antibodies were also found in patients with significant clinical conditions including malignancies even though there was no suggestion of autoimmunity at the time of testing.

Autoimmunity in 2014

Our PubMed search for peer-reviewed articles published in the 2014 solar year retrieved a significantly higher number of hits compared to 2013 with a net 28 % increase. Importantly, full articles related to autoimmunity constitute approximately 5 % of immunology articles. We confirm that our understanding of autoimmunity is becoming a translational paradigm with pathogenetic elements rapidly followed by new treatment options. Furthermore, numerous clinical and pathogenetic elements and features are shared among autoimmune diseases, and this is well illustrated in the recent literature. More specifically, the past year witnessed critical revisions of our understanding and management of antiphospholipid syndrome with new exciting data on the pathogenicity of the serum anti-beta2 glycoprotein autoantibody, a better understanding of the current and new treatments for rheumatoid arthritis, and new position papers on important clinical questions such as vaccinations in patients with autoimmune disease, comorbidities, or new classification criteria. Furthermore, data confirming the important connections between innate immunity and autoimmunity via toll-like receptors or the critical role of T regulatory cells in tolerance breakdown and autoimmunity perpetuation were also reported. Lastly, genetic and epigenetic data were provided to confirm that the mosaic of autoimmunity warrants a susceptible individual background which may be geographically determined and contribute to the geoepidemiology of diseases. The 2014 literature in the autoimmunity world should be cumulatively regarded as part of an annus mirabilis in which, on a different level, the 2014 Annual Meeting of the American College of Rheumatology in Boston was attended by over 16,000 participants with over selected 3000 abstracts.

Update on the immunobiology of Sjögren's syndrome

PURPOSE OF REVIEW

The purpose of this review is to give an update on the understanding of the immune responses involved in the pathogenesis of primary Sjögren's syndrome (pSS), and to highlight recent findings on the underlying molecular and cellular mechanisms at play.

RECENT FINDINGS

In recent years, genetic studies have confirmed the importance of aberrant type I interferon (IFN) and B cell responses in pSS and highlighted critical pathways involved in disease pathogenesis. In particular, the formation of ectopic lymphoid structures has emerged as an important factor in the establishment of chronic autoimmune responses in target organs. Interestingly, recent studies on viral infection in the context of pSS, as well as findings on the contribution of salivary gland epithelial cells in local immune responses, offer further clues to understand pSS etiology and its target organ specificity. Finally, new evidence brings T cells and natural killer cells under renewed attention as possible important contributors to pSS pathogenesis.

SUMMARY

Progress made during the last few years on the pathogenesis of pSS has been mirrored by clinical trials directed at inhibiting cytokines, B, or T cell responses. Future efforts should focus on identifying additional pSS specific targets and developing methods to help choose optimal therapeutic strategies for the individual patient.

Salivary Gland Pathology in Sjögren's Syndrome

Primary Sjögren syndrome (pSS) can be considered a systemic autoimmune disease with a strong organ bias. The involvement of the exocrine glands is prevalent and drives the pathognomonic manifestations of dryness that define the sicca syndrome. The salivary glands also represent the hub of pSS pathology. Elements belonging to both innate and acquired immune responses have been described at this site that contribute to disease establishment and progression. The interaction between those elements and their relative contributions to the clinical manifestations and lymphoma progression largely remain to be addressed.

Interaction between innate immunity and Ro52-induced antibody causes Sjögren's syndrome-like disorder in mice

OBJECTIVES

Autoantibodies reactive with Ro52 are often found in sera of patients with Sjögren's syndrome (SS). This study was undertaken to investigate the role of Ro52-induced immune responses in pathogenesis of SS.

METHODS

New Zealand Mixed (NZM) 2758 mice were immunised with Ro52 in alum adjuvant. Control mice were immunised either with maltose-binding protein or injected with alum alone. Mice were monitored for anti-Ro52 antibody, sialoadenitis and pilocarpine-induced salivation. Antibody binding to salivary gland (SG) cells was analysed in vivo and in vitro by immunofluorescence. Sera from immunised mice were passively transferred into untreated or alum injected NZM2758 mice.

RESULTS

By day 30 post-immunisation, Ro52 immunised mice generated immunoprecipitating anti-Ro52 antibodies and they had the maximum drop in saliva production. Both Ro52 immunised and control mice showed evidence of mild sialoadenitis. However, only Ro52 immunised mice had antibody deposition in their SG. Passive transfer of Ro52-immune sera induced SG dysfunction in recipient mice, only if the recipients were primed with alum. In vitro, antibodies from Ro52-immune sera were internalised by a SG cell line and this uptake was inhibited by cytochalasin D treatment.

CONCLUSIONS

Our data show for the first time that antibodies induced by Ro52 are capable of inducing SG dysfunction, and that this phenomenon is dependent on the activation of innate immunity. The mouse model described in this study implies that autoantibody deposition in the SG might be an important step in the induction of xerostomia and pathogenesis of SS.

Reduced expression of TRIM21/Ro52 predicts poor prognosis in diffuse large B-cell lymphoma patients with and without rheumatic disease

OBJECTIVE

TRIM21 (also known as Ro52) is an autoantigen in rheumatic disease and is predominantly expressed in leucocytes. Overexpression is associated with decreased proliferation, and the TRIM21 gene maps to a tumour suppressor locus. We therefore investigated the expression of TRIM21 in patients with diffuse large B-cell lymphoma (DLBCL) and its potential usefulness as a prognostic biomarker.

MATERIALS AND METHODS

TRIM21 expression levels were assessed by immunohistochemistry in lymphoma biopsies from three cohorts of patients with DLBCL: 42 patients with rheumatic disease treated with a cyclophosphamide, vincristine, doxorubicin and prednisone (CHOP)-like regimen, 76 CHOP-treated and 196 rituximab-CHOP-treated nonrheumatic patients. Expression was correlated with clinical and biomedical parameters. TRIM21 expression was assessed in relation to lymphocyte proliferation by quantitative PCR and correlated with (3) H-thymidine incorporation and propidium iodine staining.

RESULTS

TRIM21 expression levels differed in the lymphomas compared to normal lymphoid tissue, with reduced expression correlating with shorter overall survival in all three cohorts. In the two larger cohorts, progression-free survival was assessed and was also found to correlate with TRIM21 expression. The association was independent of commonly used clinical prognostic scores, lymphoma subtype and several previously reported prognostic biomarkers. In agreement with this clinical observation, we noted an inverse correlation between TRIM21 expression and proliferation of leucocytes in vitro.

CONCLUSIONS

We show that loss of TRIM21 expression is associated with more aggressive lymphoma and increased proliferation, whereas maintenance of TRIM21 expression is associated with better prognosis in patients with DLBCL. Based on our findings, we suggest that TRIM21 should be considered as a novel biomarker for lymphoma characterization and for predicting patient survival.

Interferon gamma-inducible protein 16 in primary Sjögren's syndrome: a novel player in disease pathogenesis?

Introduction

There is evidence that interferon is involved in the pathogenesis of primary Sjögren’s syndrome (pSS). The interferon-inducible IFI16 protein, normally expressed in cell nuclei, may be overexpressed, mislocalized in the cytoplasm and secreted in the extracellular milieu in several autoimmune disorders. This leads to tolerance breaking to this self-protein with consequent development of anti-IFI16 antibodies. The aim of this study was to identify the pathogenic and clinical significance of IFI16 and anti-IFI16 in pSS.

Methods

IFI16 and anti-IFI16 were assessed in the serum of 67 pSS patients and over 100 healthy donors by enzyme-linked immunosorbent assay. IFI16 was also evaluated by immunohistochemistry in minor salivary glands of 15 pSS patients and 10 subjects with sicca symptoms but without any clinical, serological or histological features of pSS.

Results

pSS patients display higher serum levels of both IFI16 and anti-IFI16 compared to healthy donors. IFI16 concentration was directly correlated with disease duration and focus score and inversely correlated with age at diagnosis. Moreover, IFI16 positivity was associated with concurrent positivity for rheumatoid factor. Interestingly, the direct correlation between IFI16 positivity and focus score was independent of disease duration and age at diagnosis. pSS minor salivary glands display marked expression and cytoplasmic mislocalization of IFI16 by acinar and ductal epithelial cells as well as infiltrating lymphocytes and peri/intralesional endothelium compared to minor salivary glands with normal architecture or nonspecific chronic sialadenitis. Within the mononuclear cell infiltrate, IFI16 expression appears to parallel the distribution of T lymphocytes.

Conclusion

Our data suggest that the IFI16 protein may be involved in the pathogenesis of glandular inflammation occurring in pSS.